1 //===- SemaTemplateDeduction.cpp - Template Argument Deduction ------------===//
3 // Part of the LLVM Project, under the Apache License v2.0 with LLVM Exceptions.
4 // See https://llvm.org/LICENSE.txt for license information.
5 // SPDX-License-Identifier: Apache-2.0 WITH LLVM-exception
7 //===----------------------------------------------------------------------===//
9 // This file implements C++ template argument deduction.
11 //===----------------------------------------------------------------------===//
13 #include "clang/Sema/TemplateDeduction.h"
14 #include "TreeTransform.h"
15 #include "TypeLocBuilder.h"
16 #include "clang/AST/ASTContext.h"
17 #include "clang/AST/ASTLambda.h"
18 #include "clang/AST/Decl.h"
19 #include "clang/AST/DeclAccessPair.h"
20 #include "clang/AST/DeclBase.h"
21 #include "clang/AST/DeclCXX.h"
22 #include "clang/AST/DeclTemplate.h"
23 #include "clang/AST/DeclarationName.h"
24 #include "clang/AST/Expr.h"
25 #include "clang/AST/ExprCXX.h"
26 #include "clang/AST/NestedNameSpecifier.h"
27 #include "clang/AST/RecursiveASTVisitor.h"
28 #include "clang/AST/TemplateBase.h"
29 #include "clang/AST/TemplateName.h"
30 #include "clang/AST/Type.h"
31 #include "clang/AST/TypeLoc.h"
32 #include "clang/AST/UnresolvedSet.h"
33 #include "clang/Basic/AddressSpaces.h"
34 #include "clang/Basic/ExceptionSpecificationType.h"
35 #include "clang/Basic/LLVM.h"
36 #include "clang/Basic/LangOptions.h"
37 #include "clang/Basic/PartialDiagnostic.h"
38 #include "clang/Basic/SourceLocation.h"
39 #include "clang/Basic/Specifiers.h"
40 #include "clang/Sema/Ownership.h"
41 #include "clang/Sema/Sema.h"
42 #include "clang/Sema/Template.h"
43 #include "llvm/ADT/APInt.h"
44 #include "llvm/ADT/APSInt.h"
45 #include "llvm/ADT/ArrayRef.h"
46 #include "llvm/ADT/DenseMap.h"
47 #include "llvm/ADT/FoldingSet.h"
48 #include "llvm/ADT/Optional.h"
49 #include "llvm/ADT/SmallBitVector.h"
50 #include "llvm/ADT/SmallPtrSet.h"
51 #include "llvm/ADT/SmallVector.h"
52 #include "llvm/Support/Casting.h"
53 #include "llvm/Support/Compiler.h"
54 #include "llvm/Support/ErrorHandling.h"
62 /// Various flags that control template argument deduction.
64 /// These flags can be bitwise-OR'd together.
65 enum TemplateDeductionFlags {
66 /// No template argument deduction flags, which indicates the
67 /// strictest results for template argument deduction (as used for, e.g.,
68 /// matching class template partial specializations).
71 /// Within template argument deduction from a function call, we are
72 /// matching with a parameter type for which the original parameter was
74 TDF_ParamWithReferenceType = 0x1,
76 /// Within template argument deduction from a function call, we
77 /// are matching in a case where we ignore cv-qualifiers.
78 TDF_IgnoreQualifiers = 0x02,
80 /// Within template argument deduction from a function call,
81 /// we are matching in a case where we can perform template argument
82 /// deduction from a template-id of a derived class of the argument type.
83 TDF_DerivedClass = 0x04,
85 /// Allow non-dependent types to differ, e.g., when performing
86 /// template argument deduction from a function call where conversions
88 TDF_SkipNonDependent = 0x08,
90 /// Whether we are performing template argument deduction for
91 /// parameters and arguments in a top-level template argument
92 TDF_TopLevelParameterTypeList = 0x10,
94 /// Within template argument deduction from overload resolution per
95 /// C++ [over.over] allow matching function types that are compatible in
96 /// terms of noreturn and default calling convention adjustments, or
97 /// similarly matching a declared template specialization against a
98 /// possible template, per C++ [temp.deduct.decl]. In either case, permit
99 /// deduction where the parameter is a function type that can be converted
100 /// to the argument type.
101 TDF_AllowCompatibleFunctionType = 0x20,
103 /// Within template argument deduction for a conversion function, we are
104 /// matching with an argument type for which the original argument was
106 TDF_ArgWithReferenceType = 0x40,
110 using namespace clang;
111 using namespace sema;
113 /// Compare two APSInts, extending and switching the sign as
114 /// necessary to compare their values regardless of underlying type.
115 static bool hasSameExtendedValue(llvm::APSInt X, llvm::APSInt Y) {
116 if (Y.getBitWidth() > X.getBitWidth())
117 X = X.extend(Y.getBitWidth());
118 else if (Y.getBitWidth() < X.getBitWidth())
119 Y = Y.extend(X.getBitWidth());
121 // If there is a signedness mismatch, correct it.
122 if (X.isSigned() != Y.isSigned()) {
123 // If the signed value is negative, then the values cannot be the same.
124 if ((Y.isSigned() && Y.isNegative()) || (X.isSigned() && X.isNegative()))
134 static Sema::TemplateDeductionResult
135 DeduceTemplateArguments(Sema &S,
136 TemplateParameterList *TemplateParams,
137 const TemplateArgument &Param,
138 TemplateArgument Arg,
139 TemplateDeductionInfo &Info,
140 SmallVectorImpl<DeducedTemplateArgument> &Deduced);
142 static Sema::TemplateDeductionResult
143 DeduceTemplateArgumentsByTypeMatch(Sema &S,
144 TemplateParameterList *TemplateParams,
147 TemplateDeductionInfo &Info,
148 SmallVectorImpl<DeducedTemplateArgument> &
151 bool PartialOrdering = false,
152 bool DeducedFromArrayBound = false);
154 static Sema::TemplateDeductionResult
155 DeduceTemplateArguments(Sema &S, TemplateParameterList *TemplateParams,
156 ArrayRef<TemplateArgument> Params,
157 ArrayRef<TemplateArgument> Args,
158 TemplateDeductionInfo &Info,
159 SmallVectorImpl<DeducedTemplateArgument> &Deduced,
160 bool NumberOfArgumentsMustMatch);
162 static void MarkUsedTemplateParameters(ASTContext &Ctx,
163 const TemplateArgument &TemplateArg,
164 bool OnlyDeduced, unsigned Depth,
165 llvm::SmallBitVector &Used);
167 static void MarkUsedTemplateParameters(ASTContext &Ctx, QualType T,
168 bool OnlyDeduced, unsigned Level,
169 llvm::SmallBitVector &Deduced);
171 /// If the given expression is of a form that permits the deduction
172 /// of a non-type template parameter, return the declaration of that
173 /// non-type template parameter.
174 static NonTypeTemplateParmDecl *
175 getDeducedParameterFromExpr(TemplateDeductionInfo &Info, Expr *E) {
176 // If we are within an alias template, the expression may have undergone
177 // any number of parameter substitutions already.
179 if (ImplicitCastExpr *IC = dyn_cast<ImplicitCastExpr>(E))
180 E = IC->getSubExpr();
181 else if (ConstantExpr *CE = dyn_cast<ConstantExpr>(E))
182 E = CE->getSubExpr();
183 else if (SubstNonTypeTemplateParmExpr *Subst =
184 dyn_cast<SubstNonTypeTemplateParmExpr>(E))
185 E = Subst->getReplacement();
190 if (DeclRefExpr *DRE = dyn_cast<DeclRefExpr>(E))
191 if (auto *NTTP = dyn_cast<NonTypeTemplateParmDecl>(DRE->getDecl()))
192 if (NTTP->getDepth() == Info.getDeducedDepth())
198 /// Determine whether two declaration pointers refer to the same
200 static bool isSameDeclaration(Decl *X, Decl *Y) {
201 if (NamedDecl *NX = dyn_cast<NamedDecl>(X))
202 X = NX->getUnderlyingDecl();
203 if (NamedDecl *NY = dyn_cast<NamedDecl>(Y))
204 Y = NY->getUnderlyingDecl();
206 return X->getCanonicalDecl() == Y->getCanonicalDecl();
209 /// Verify that the given, deduced template arguments are compatible.
211 /// \returns The deduced template argument, or a NULL template argument if
212 /// the deduced template arguments were incompatible.
213 static DeducedTemplateArgument
214 checkDeducedTemplateArguments(ASTContext &Context,
215 const DeducedTemplateArgument &X,
216 const DeducedTemplateArgument &Y) {
217 // We have no deduction for one or both of the arguments; they're compatible.
223 // If we have two non-type template argument values deduced for the same
224 // parameter, they must both match the type of the parameter, and thus must
225 // match each other's type. As we're only keeping one of them, we must check
226 // for that now. The exception is that if either was deduced from an array
227 // bound, the type is permitted to differ.
228 if (!X.wasDeducedFromArrayBound() && !Y.wasDeducedFromArrayBound()) {
229 QualType XType = X.getNonTypeTemplateArgumentType();
230 if (!XType.isNull()) {
231 QualType YType = Y.getNonTypeTemplateArgumentType();
232 if (YType.isNull() || !Context.hasSameType(XType, YType))
233 return DeducedTemplateArgument();
237 switch (X.getKind()) {
238 case TemplateArgument::Null:
239 llvm_unreachable("Non-deduced template arguments handled above");
241 case TemplateArgument::Type:
242 // If two template type arguments have the same type, they're compatible.
243 if (Y.getKind() == TemplateArgument::Type &&
244 Context.hasSameType(X.getAsType(), Y.getAsType()))
247 // If one of the two arguments was deduced from an array bound, the other
249 if (X.wasDeducedFromArrayBound() != Y.wasDeducedFromArrayBound())
250 return X.wasDeducedFromArrayBound() ? Y : X;
252 // The arguments are not compatible.
253 return DeducedTemplateArgument();
255 case TemplateArgument::Integral:
256 // If we deduced a constant in one case and either a dependent expression or
257 // declaration in another case, keep the integral constant.
258 // If both are integral constants with the same value, keep that value.
259 if (Y.getKind() == TemplateArgument::Expression ||
260 Y.getKind() == TemplateArgument::Declaration ||
261 (Y.getKind() == TemplateArgument::Integral &&
262 hasSameExtendedValue(X.getAsIntegral(), Y.getAsIntegral())))
263 return X.wasDeducedFromArrayBound() ? Y : X;
265 // All other combinations are incompatible.
266 return DeducedTemplateArgument();
268 case TemplateArgument::Template:
269 if (Y.getKind() == TemplateArgument::Template &&
270 Context.hasSameTemplateName(X.getAsTemplate(), Y.getAsTemplate()))
273 // All other combinations are incompatible.
274 return DeducedTemplateArgument();
276 case TemplateArgument::TemplateExpansion:
277 if (Y.getKind() == TemplateArgument::TemplateExpansion &&
278 Context.hasSameTemplateName(X.getAsTemplateOrTemplatePattern(),
279 Y.getAsTemplateOrTemplatePattern()))
282 // All other combinations are incompatible.
283 return DeducedTemplateArgument();
285 case TemplateArgument::Expression: {
286 if (Y.getKind() != TemplateArgument::Expression)
287 return checkDeducedTemplateArguments(Context, Y, X);
289 // Compare the expressions for equality
290 llvm::FoldingSetNodeID ID1, ID2;
291 X.getAsExpr()->Profile(ID1, Context, true);
292 Y.getAsExpr()->Profile(ID2, Context, true);
294 return X.wasDeducedFromArrayBound() ? Y : X;
296 // Differing dependent expressions are incompatible.
297 return DeducedTemplateArgument();
300 case TemplateArgument::Declaration:
301 assert(!X.wasDeducedFromArrayBound());
303 // If we deduced a declaration and a dependent expression, keep the
305 if (Y.getKind() == TemplateArgument::Expression)
308 // If we deduced a declaration and an integral constant, keep the
309 // integral constant and whichever type did not come from an array
311 if (Y.getKind() == TemplateArgument::Integral) {
312 if (Y.wasDeducedFromArrayBound())
313 return TemplateArgument(Context, Y.getAsIntegral(),
314 X.getParamTypeForDecl());
318 // If we deduced two declarations, make sure that they refer to the
320 if (Y.getKind() == TemplateArgument::Declaration &&
321 isSameDeclaration(X.getAsDecl(), Y.getAsDecl()))
324 // All other combinations are incompatible.
325 return DeducedTemplateArgument();
327 case TemplateArgument::NullPtr:
328 // If we deduced a null pointer and a dependent expression, keep the
330 if (Y.getKind() == TemplateArgument::Expression)
333 // If we deduced a null pointer and an integral constant, keep the
334 // integral constant.
335 if (Y.getKind() == TemplateArgument::Integral)
338 // If we deduced two null pointers, they are the same.
339 if (Y.getKind() == TemplateArgument::NullPtr)
342 // All other combinations are incompatible.
343 return DeducedTemplateArgument();
345 case TemplateArgument::Pack: {
346 if (Y.getKind() != TemplateArgument::Pack ||
347 X.pack_size() != Y.pack_size())
348 return DeducedTemplateArgument();
350 llvm::SmallVector<TemplateArgument, 8> NewPack;
351 for (TemplateArgument::pack_iterator XA = X.pack_begin(),
352 XAEnd = X.pack_end(),
354 XA != XAEnd; ++XA, ++YA) {
355 TemplateArgument Merged = checkDeducedTemplateArguments(
356 Context, DeducedTemplateArgument(*XA, X.wasDeducedFromArrayBound()),
357 DeducedTemplateArgument(*YA, Y.wasDeducedFromArrayBound()));
358 if (Merged.isNull() && !(XA->isNull() && YA->isNull()))
359 return DeducedTemplateArgument();
360 NewPack.push_back(Merged);
363 return DeducedTemplateArgument(
364 TemplateArgument::CreatePackCopy(Context, NewPack),
365 X.wasDeducedFromArrayBound() && Y.wasDeducedFromArrayBound());
369 llvm_unreachable("Invalid TemplateArgument Kind!");
372 /// Deduce the value of the given non-type template parameter
373 /// as the given deduced template argument. All non-type template parameter
374 /// deduction is funneled through here.
375 static Sema::TemplateDeductionResult DeduceNonTypeTemplateArgument(
376 Sema &S, TemplateParameterList *TemplateParams,
377 NonTypeTemplateParmDecl *NTTP, const DeducedTemplateArgument &NewDeduced,
378 QualType ValueType, TemplateDeductionInfo &Info,
379 SmallVectorImpl<DeducedTemplateArgument> &Deduced) {
380 assert(NTTP->getDepth() == Info.getDeducedDepth() &&
381 "deducing non-type template argument with wrong depth");
383 DeducedTemplateArgument Result = checkDeducedTemplateArguments(
384 S.Context, Deduced[NTTP->getIndex()], NewDeduced);
385 if (Result.isNull()) {
387 Info.FirstArg = Deduced[NTTP->getIndex()];
388 Info.SecondArg = NewDeduced;
389 return Sema::TDK_Inconsistent;
392 Deduced[NTTP->getIndex()] = Result;
393 if (!S.getLangOpts().CPlusPlus17)
394 return Sema::TDK_Success;
396 if (NTTP->isExpandedParameterPack())
397 // FIXME: We may still need to deduce parts of the type here! But we
398 // don't have any way to find which slice of the type to use, and the
399 // type stored on the NTTP itself is nonsense. Perhaps the type of an
400 // expanded NTTP should be a pack expansion type?
401 return Sema::TDK_Success;
403 // Get the type of the parameter for deduction. If it's a (dependent) array
404 // or function type, we will not have decayed it yet, so do that now.
405 QualType ParamType = S.Context.getAdjustedParameterType(NTTP->getType());
406 if (auto *Expansion = dyn_cast<PackExpansionType>(ParamType))
407 ParamType = Expansion->getPattern();
409 // FIXME: It's not clear how deduction of a parameter of reference
410 // type from an argument (of non-reference type) should be performed.
411 // For now, we just remove reference types from both sides and let
412 // the final check for matching types sort out the mess.
413 return DeduceTemplateArgumentsByTypeMatch(
414 S, TemplateParams, ParamType.getNonReferenceType(),
415 ValueType.getNonReferenceType(), Info, Deduced, TDF_SkipNonDependent,
416 /*PartialOrdering=*/false,
417 /*ArrayBound=*/NewDeduced.wasDeducedFromArrayBound());
420 /// Deduce the value of the given non-type template parameter
421 /// from the given integral constant.
422 static Sema::TemplateDeductionResult DeduceNonTypeTemplateArgument(
423 Sema &S, TemplateParameterList *TemplateParams,
424 NonTypeTemplateParmDecl *NTTP, const llvm::APSInt &Value,
425 QualType ValueType, bool DeducedFromArrayBound, TemplateDeductionInfo &Info,
426 SmallVectorImpl<DeducedTemplateArgument> &Deduced) {
427 return DeduceNonTypeTemplateArgument(
428 S, TemplateParams, NTTP,
429 DeducedTemplateArgument(S.Context, Value, ValueType,
430 DeducedFromArrayBound),
431 ValueType, Info, Deduced);
434 /// Deduce the value of the given non-type template parameter
435 /// from the given null pointer template argument type.
436 static Sema::TemplateDeductionResult DeduceNullPtrTemplateArgument(
437 Sema &S, TemplateParameterList *TemplateParams,
438 NonTypeTemplateParmDecl *NTTP, QualType NullPtrType,
439 TemplateDeductionInfo &Info,
440 SmallVectorImpl<DeducedTemplateArgument> &Deduced) {
442 S.ImpCastExprToType(new (S.Context) CXXNullPtrLiteralExpr(
443 S.Context.NullPtrTy, NTTP->getLocation()),
444 NullPtrType, CK_NullToPointer)
446 return DeduceNonTypeTemplateArgument(S, TemplateParams, NTTP,
447 DeducedTemplateArgument(Value),
448 Value->getType(), Info, Deduced);
451 /// Deduce the value of the given non-type template parameter
452 /// from the given type- or value-dependent expression.
454 /// \returns true if deduction succeeded, false otherwise.
455 static Sema::TemplateDeductionResult DeduceNonTypeTemplateArgument(
456 Sema &S, TemplateParameterList *TemplateParams,
457 NonTypeTemplateParmDecl *NTTP, Expr *Value, TemplateDeductionInfo &Info,
458 SmallVectorImpl<DeducedTemplateArgument> &Deduced) {
459 return DeduceNonTypeTemplateArgument(S, TemplateParams, NTTP,
460 DeducedTemplateArgument(Value),
461 Value->getType(), Info, Deduced);
464 /// Deduce the value of the given non-type template parameter
465 /// from the given declaration.
467 /// \returns true if deduction succeeded, false otherwise.
468 static Sema::TemplateDeductionResult DeduceNonTypeTemplateArgument(
469 Sema &S, TemplateParameterList *TemplateParams,
470 NonTypeTemplateParmDecl *NTTP, ValueDecl *D, QualType T,
471 TemplateDeductionInfo &Info,
472 SmallVectorImpl<DeducedTemplateArgument> &Deduced) {
473 D = D ? cast<ValueDecl>(D->getCanonicalDecl()) : nullptr;
474 TemplateArgument New(D, T);
475 return DeduceNonTypeTemplateArgument(
476 S, TemplateParams, NTTP, DeducedTemplateArgument(New), T, Info, Deduced);
479 static Sema::TemplateDeductionResult
480 DeduceTemplateArguments(Sema &S,
481 TemplateParameterList *TemplateParams,
484 TemplateDeductionInfo &Info,
485 SmallVectorImpl<DeducedTemplateArgument> &Deduced) {
486 TemplateDecl *ParamDecl = Param.getAsTemplateDecl();
488 // The parameter type is dependent and is not a template template parameter,
489 // so there is nothing that we can deduce.
490 return Sema::TDK_Success;
493 if (TemplateTemplateParmDecl *TempParam
494 = dyn_cast<TemplateTemplateParmDecl>(ParamDecl)) {
495 // If we're not deducing at this depth, there's nothing to deduce.
496 if (TempParam->getDepth() != Info.getDeducedDepth())
497 return Sema::TDK_Success;
499 DeducedTemplateArgument NewDeduced(S.Context.getCanonicalTemplateName(Arg));
500 DeducedTemplateArgument Result = checkDeducedTemplateArguments(S.Context,
501 Deduced[TempParam->getIndex()],
503 if (Result.isNull()) {
504 Info.Param = TempParam;
505 Info.FirstArg = Deduced[TempParam->getIndex()];
506 Info.SecondArg = NewDeduced;
507 return Sema::TDK_Inconsistent;
510 Deduced[TempParam->getIndex()] = Result;
511 return Sema::TDK_Success;
514 // Verify that the two template names are equivalent.
515 if (S.Context.hasSameTemplateName(Param, Arg))
516 return Sema::TDK_Success;
518 // Mismatch of non-dependent template parameter to argument.
519 Info.FirstArg = TemplateArgument(Param);
520 Info.SecondArg = TemplateArgument(Arg);
521 return Sema::TDK_NonDeducedMismatch;
524 /// Deduce the template arguments by comparing the template parameter
525 /// type (which is a template-id) with the template argument type.
527 /// \param S the Sema
529 /// \param TemplateParams the template parameters that we are deducing
531 /// \param Param the parameter type
533 /// \param Arg the argument type
535 /// \param Info information about the template argument deduction itself
537 /// \param Deduced the deduced template arguments
539 /// \returns the result of template argument deduction so far. Note that a
540 /// "success" result means that template argument deduction has not yet failed,
541 /// but it may still fail, later, for other reasons.
542 static Sema::TemplateDeductionResult
543 DeduceTemplateArguments(Sema &S,
544 TemplateParameterList *TemplateParams,
545 const TemplateSpecializationType *Param,
547 TemplateDeductionInfo &Info,
548 SmallVectorImpl<DeducedTemplateArgument> &Deduced) {
549 assert(Arg.isCanonical() && "Argument type must be canonical");
551 // Treat an injected-class-name as its underlying template-id.
552 if (auto *Injected = dyn_cast<InjectedClassNameType>(Arg))
553 Arg = Injected->getInjectedSpecializationType();
555 // Check whether the template argument is a dependent template-id.
556 if (const TemplateSpecializationType *SpecArg
557 = dyn_cast<TemplateSpecializationType>(Arg)) {
558 // Perform template argument deduction for the template name.
559 if (Sema::TemplateDeductionResult Result
560 = DeduceTemplateArguments(S, TemplateParams,
561 Param->getTemplateName(),
562 SpecArg->getTemplateName(),
567 // Perform template argument deduction on each template
568 // argument. Ignore any missing/extra arguments, since they could be
569 // filled in by default arguments.
570 return DeduceTemplateArguments(S, TemplateParams,
571 Param->template_arguments(),
572 SpecArg->template_arguments(), Info, Deduced,
573 /*NumberOfArgumentsMustMatch=*/false);
576 // If the argument type is a class template specialization, we
577 // perform template argument deduction using its template
579 const RecordType *RecordArg = dyn_cast<RecordType>(Arg);
581 Info.FirstArg = TemplateArgument(QualType(Param, 0));
582 Info.SecondArg = TemplateArgument(Arg);
583 return Sema::TDK_NonDeducedMismatch;
586 ClassTemplateSpecializationDecl *SpecArg
587 = dyn_cast<ClassTemplateSpecializationDecl>(RecordArg->getDecl());
589 Info.FirstArg = TemplateArgument(QualType(Param, 0));
590 Info.SecondArg = TemplateArgument(Arg);
591 return Sema::TDK_NonDeducedMismatch;
594 // Perform template argument deduction for the template name.
595 if (Sema::TemplateDeductionResult Result
596 = DeduceTemplateArguments(S,
598 Param->getTemplateName(),
599 TemplateName(SpecArg->getSpecializedTemplate()),
603 // Perform template argument deduction for the template arguments.
604 return DeduceTemplateArguments(S, TemplateParams, Param->template_arguments(),
605 SpecArg->getTemplateArgs().asArray(), Info,
606 Deduced, /*NumberOfArgumentsMustMatch=*/true);
609 /// Determines whether the given type is an opaque type that
610 /// might be more qualified when instantiated.
611 static bool IsPossiblyOpaquelyQualifiedType(QualType T) {
612 switch (T->getTypeClass()) {
613 case Type::TypeOfExpr:
615 case Type::DependentName:
617 case Type::UnresolvedUsing:
618 case Type::TemplateTypeParm:
621 case Type::ConstantArray:
622 case Type::IncompleteArray:
623 case Type::VariableArray:
624 case Type::DependentSizedArray:
625 return IsPossiblyOpaquelyQualifiedType(
626 cast<ArrayType>(T)->getElementType());
633 /// Helper function to build a TemplateParameter when we don't
634 /// know its type statically.
635 static TemplateParameter makeTemplateParameter(Decl *D) {
636 if (TemplateTypeParmDecl *TTP = dyn_cast<TemplateTypeParmDecl>(D))
637 return TemplateParameter(TTP);
638 if (NonTypeTemplateParmDecl *NTTP = dyn_cast<NonTypeTemplateParmDecl>(D))
639 return TemplateParameter(NTTP);
641 return TemplateParameter(cast<TemplateTemplateParmDecl>(D));
644 /// If \p Param is an expanded parameter pack, get the number of expansions.
645 static Optional<unsigned> getExpandedPackSize(NamedDecl *Param) {
646 if (auto *TTP = dyn_cast<TemplateTypeParmDecl>(Param))
647 if (TTP->isExpandedParameterPack())
648 return TTP->getNumExpansionParameters();
650 if (auto *NTTP = dyn_cast<NonTypeTemplateParmDecl>(Param))
651 if (NTTP->isExpandedParameterPack())
652 return NTTP->getNumExpansionTypes();
654 if (auto *TTP = dyn_cast<TemplateTemplateParmDecl>(Param))
655 if (TTP->isExpandedParameterPack())
656 return TTP->getNumExpansionTemplateParameters();
661 /// A pack that we're currently deducing.
662 struct clang::DeducedPack {
663 // The index of the pack.
666 // The old value of the pack before we started deducing it.
667 DeducedTemplateArgument Saved;
669 // A deferred value of this pack from an inner deduction, that couldn't be
670 // deduced because this deduction hadn't happened yet.
671 DeducedTemplateArgument DeferredDeduction;
673 // The new value of the pack.
674 SmallVector<DeducedTemplateArgument, 4> New;
676 // The outer deduction for this pack, if any.
677 DeducedPack *Outer = nullptr;
679 DeducedPack(unsigned Index) : Index(Index) {}
684 /// A scope in which we're performing pack deduction.
685 class PackDeductionScope {
687 /// Prepare to deduce the packs named within Pattern.
688 PackDeductionScope(Sema &S, TemplateParameterList *TemplateParams,
689 SmallVectorImpl<DeducedTemplateArgument> &Deduced,
690 TemplateDeductionInfo &Info, TemplateArgument Pattern)
691 : S(S), TemplateParams(TemplateParams), Deduced(Deduced), Info(Info) {
692 unsigned NumNamedPacks = addPacks(Pattern);
693 finishConstruction(NumNamedPacks);
696 /// Prepare to directly deduce arguments of the parameter with index \p Index.
697 PackDeductionScope(Sema &S, TemplateParameterList *TemplateParams,
698 SmallVectorImpl<DeducedTemplateArgument> &Deduced,
699 TemplateDeductionInfo &Info, unsigned Index)
700 : S(S), TemplateParams(TemplateParams), Deduced(Deduced), Info(Info) {
702 finishConstruction(1);
706 void addPack(unsigned Index) {
707 // Save the deduced template argument for the parameter pack expanded
708 // by this pack expansion, then clear out the deduction.
709 DeducedPack Pack(Index);
710 Pack.Saved = Deduced[Index];
711 Deduced[Index] = TemplateArgument();
713 // FIXME: What if we encounter multiple packs with different numbers of
714 // pre-expanded expansions? (This should already have been diagnosed
715 // during substitution.)
716 if (Optional<unsigned> ExpandedPackExpansions =
717 getExpandedPackSize(TemplateParams->getParam(Index)))
718 FixedNumExpansions = ExpandedPackExpansions;
720 Packs.push_back(Pack);
723 unsigned addPacks(TemplateArgument Pattern) {
724 // Compute the set of template parameter indices that correspond to
725 // parameter packs expanded by the pack expansion.
726 llvm::SmallBitVector SawIndices(TemplateParams->size());
727 llvm::SmallVector<TemplateArgument, 4> ExtraDeductions;
729 auto AddPack = [&](unsigned Index) {
730 if (SawIndices[Index])
732 SawIndices[Index] = true;
735 // Deducing a parameter pack that is a pack expansion also constrains the
736 // packs appearing in that parameter to have the same deduced arity. Also,
737 // in C++17 onwards, deducing a non-type template parameter deduces its
738 // type, so we need to collect the pending deduced values for those packs.
739 if (auto *NTTP = dyn_cast<NonTypeTemplateParmDecl>(
740 TemplateParams->getParam(Index))) {
741 if (!NTTP->isExpandedParameterPack())
742 if (auto *Expansion = dyn_cast<PackExpansionType>(NTTP->getType()))
743 ExtraDeductions.push_back(Expansion->getPattern());
745 // FIXME: Also collect the unexpanded packs in any type and template
746 // parameter packs that are pack expansions.
749 auto Collect = [&](TemplateArgument Pattern) {
750 SmallVector<UnexpandedParameterPack, 2> Unexpanded;
751 S.collectUnexpandedParameterPacks(Pattern, Unexpanded);
752 for (unsigned I = 0, N = Unexpanded.size(); I != N; ++I) {
753 unsigned Depth, Index;
754 std::tie(Depth, Index) = getDepthAndIndex(Unexpanded[I]);
755 if (Depth == Info.getDeducedDepth())
760 // Look for unexpanded packs in the pattern.
762 assert(!Packs.empty() && "Pack expansion without unexpanded packs?");
764 unsigned NumNamedPacks = Packs.size();
766 // Also look for unexpanded packs that are indirectly deduced by deducing
767 // the sizes of the packs in this pattern.
768 while (!ExtraDeductions.empty())
769 Collect(ExtraDeductions.pop_back_val());
771 return NumNamedPacks;
774 void finishConstruction(unsigned NumNamedPacks) {
775 // Dig out the partially-substituted pack, if there is one.
776 const TemplateArgument *PartialPackArgs = nullptr;
777 unsigned NumPartialPackArgs = 0;
778 std::pair<unsigned, unsigned> PartialPackDepthIndex(-1u, -1u);
779 if (auto *Scope = S.CurrentInstantiationScope)
780 if (auto *Partial = Scope->getPartiallySubstitutedPack(
781 &PartialPackArgs, &NumPartialPackArgs))
782 PartialPackDepthIndex = getDepthAndIndex(Partial);
784 // This pack expansion will have been partially or fully expanded if
785 // it only names explicitly-specified parameter packs (including the
786 // partially-substituted one, if any).
787 bool IsExpanded = true;
788 for (unsigned I = 0; I != NumNamedPacks; ++I) {
789 if (Packs[I].Index >= Info.getNumExplicitArgs()) {
791 IsPartiallyExpanded = false;
794 if (PartialPackDepthIndex ==
795 std::make_pair(Info.getDeducedDepth(), Packs[I].Index)) {
796 IsPartiallyExpanded = true;
800 // Skip over the pack elements that were expanded into separate arguments.
801 // If we partially expanded, this is the number of partial arguments.
802 if (IsPartiallyExpanded)
803 PackElements += NumPartialPackArgs;
805 PackElements += *FixedNumExpansions;
807 for (auto &Pack : Packs) {
808 if (Info.PendingDeducedPacks.size() > Pack.Index)
809 Pack.Outer = Info.PendingDeducedPacks[Pack.Index];
811 Info.PendingDeducedPacks.resize(Pack.Index + 1);
812 Info.PendingDeducedPacks[Pack.Index] = &Pack;
814 if (PartialPackDepthIndex ==
815 std::make_pair(Info.getDeducedDepth(), Pack.Index)) {
816 Pack.New.append(PartialPackArgs, PartialPackArgs + NumPartialPackArgs);
817 // We pre-populate the deduced value of the partially-substituted
818 // pack with the specified value. This is not entirely correct: the
819 // value is supposed to have been substituted, not deduced, but the
820 // cases where this is observable require an exact type match anyway.
822 // FIXME: If we could represent a "depth i, index j, pack elem k"
823 // parameter, we could substitute the partially-substituted pack
824 // everywhere and avoid this.
825 if (!IsPartiallyExpanded)
826 Deduced[Pack.Index] = Pack.New[PackElements];
832 ~PackDeductionScope() {
833 for (auto &Pack : Packs)
834 Info.PendingDeducedPacks[Pack.Index] = Pack.Outer;
837 /// Determine whether this pack has already been partially expanded into a
838 /// sequence of (prior) function parameters / template arguments.
839 bool isPartiallyExpanded() { return IsPartiallyExpanded; }
841 /// Determine whether this pack expansion scope has a known, fixed arity.
842 /// This happens if it involves a pack from an outer template that has
843 /// (notionally) already been expanded.
844 bool hasFixedArity() { return FixedNumExpansions.hasValue(); }
846 /// Determine whether the next element of the argument is still part of this
847 /// pack. This is the case unless the pack is already expanded to a fixed
849 bool hasNextElement() {
850 return !FixedNumExpansions || *FixedNumExpansions > PackElements;
853 /// Move to deducing the next element in each pack that is being deduced.
854 void nextPackElement() {
855 // Capture the deduced template arguments for each parameter pack expanded
856 // by this pack expansion, add them to the list of arguments we've deduced
857 // for that pack, then clear out the deduced argument.
858 for (auto &Pack : Packs) {
859 DeducedTemplateArgument &DeducedArg = Deduced[Pack.Index];
860 if (!Pack.New.empty() || !DeducedArg.isNull()) {
861 while (Pack.New.size() < PackElements)
862 Pack.New.push_back(DeducedTemplateArgument());
863 if (Pack.New.size() == PackElements)
864 Pack.New.push_back(DeducedArg);
866 Pack.New[PackElements] = DeducedArg;
867 DeducedArg = Pack.New.size() > PackElements + 1
868 ? Pack.New[PackElements + 1]
869 : DeducedTemplateArgument();
875 /// Finish template argument deduction for a set of argument packs,
876 /// producing the argument packs and checking for consistency with prior
878 Sema::TemplateDeductionResult finish() {
879 // Build argument packs for each of the parameter packs expanded by this
881 for (auto &Pack : Packs) {
882 // Put back the old value for this pack.
883 Deduced[Pack.Index] = Pack.Saved;
885 // Always make sure the size of this pack is correct, even if we didn't
886 // deduce any values for it.
888 // FIXME: This isn't required by the normative wording, but substitution
889 // and post-substitution checking will always fail if the arity of any
890 // pack is not equal to the number of elements we processed. (Either that
891 // or something else has gone *very* wrong.) We're permitted to skip any
892 // hard errors from those follow-on steps by the intent (but not the
893 // wording) of C++ [temp.inst]p8:
895 // If the function selected by overload resolution can be determined
896 // without instantiating a class template definition, it is unspecified
897 // whether that instantiation actually takes place
898 Pack.New.resize(PackElements);
900 // Build or find a new value for this pack.
901 DeducedTemplateArgument NewPack;
902 if (Pack.New.empty()) {
903 // If we deduced an empty argument pack, create it now.
904 NewPack = DeducedTemplateArgument(TemplateArgument::getEmptyPack());
906 TemplateArgument *ArgumentPack =
907 new (S.Context) TemplateArgument[Pack.New.size()];
908 std::copy(Pack.New.begin(), Pack.New.end(), ArgumentPack);
909 NewPack = DeducedTemplateArgument(
910 TemplateArgument(llvm::makeArrayRef(ArgumentPack, Pack.New.size())),
911 // FIXME: This is wrong, it's possible that some pack elements are
912 // deduced from an array bound and others are not:
913 // template<typename ...T, T ...V> void g(const T (&...p)[V]);
914 // g({1, 2, 3}, {{}, {}});
915 // ... should deduce T = {int, size_t (from array bound)}.
916 Pack.New[0].wasDeducedFromArrayBound());
919 // Pick where we're going to put the merged pack.
920 DeducedTemplateArgument *Loc;
922 if (Pack.Outer->DeferredDeduction.isNull()) {
923 // Defer checking this pack until we have a complete pack to compare
925 Pack.Outer->DeferredDeduction = NewPack;
928 Loc = &Pack.Outer->DeferredDeduction;
930 Loc = &Deduced[Pack.Index];
933 // Check the new pack matches any previous value.
934 DeducedTemplateArgument OldPack = *Loc;
935 DeducedTemplateArgument Result =
936 checkDeducedTemplateArguments(S.Context, OldPack, NewPack);
938 // If we deferred a deduction of this pack, check that one now too.
939 if (!Result.isNull() && !Pack.DeferredDeduction.isNull()) {
941 NewPack = Pack.DeferredDeduction;
942 Result = checkDeducedTemplateArguments(S.Context, OldPack, NewPack);
945 NamedDecl *Param = TemplateParams->getParam(Pack.Index);
946 if (Result.isNull()) {
947 Info.Param = makeTemplateParameter(Param);
948 Info.FirstArg = OldPack;
949 Info.SecondArg = NewPack;
950 return Sema::TDK_Inconsistent;
953 // If we have a pre-expanded pack and we didn't deduce enough elements
954 // for it, fail deduction.
955 if (Optional<unsigned> Expansions = getExpandedPackSize(Param)) {
956 if (*Expansions != PackElements) {
957 Info.Param = makeTemplateParameter(Param);
958 Info.FirstArg = Result;
959 return Sema::TDK_IncompletePack;
966 return Sema::TDK_Success;
971 TemplateParameterList *TemplateParams;
972 SmallVectorImpl<DeducedTemplateArgument> &Deduced;
973 TemplateDeductionInfo &Info;
974 unsigned PackElements = 0;
975 bool IsPartiallyExpanded = false;
976 /// The number of expansions, if we have a fully-expanded pack in this scope.
977 Optional<unsigned> FixedNumExpansions;
979 SmallVector<DeducedPack, 2> Packs;
984 /// Deduce the template arguments by comparing the list of parameter
985 /// types to the list of argument types, as in the parameter-type-lists of
986 /// function types (C++ [temp.deduct.type]p10).
988 /// \param S The semantic analysis object within which we are deducing
990 /// \param TemplateParams The template parameters that we are deducing
992 /// \param Params The list of parameter types
994 /// \param NumParams The number of types in \c Params
996 /// \param Args The list of argument types
998 /// \param NumArgs The number of types in \c Args
1000 /// \param Info information about the template argument deduction itself
1002 /// \param Deduced the deduced template arguments
1004 /// \param TDF bitwise OR of the TemplateDeductionFlags bits that describe
1005 /// how template argument deduction is performed.
1007 /// \param PartialOrdering If true, we are performing template argument
1008 /// deduction for during partial ordering for a call
1009 /// (C++0x [temp.deduct.partial]).
1011 /// \returns the result of template argument deduction so far. Note that a
1012 /// "success" result means that template argument deduction has not yet failed,
1013 /// but it may still fail, later, for other reasons.
1014 static Sema::TemplateDeductionResult
1015 DeduceTemplateArguments(Sema &S,
1016 TemplateParameterList *TemplateParams,
1017 const QualType *Params, unsigned NumParams,
1018 const QualType *Args, unsigned NumArgs,
1019 TemplateDeductionInfo &Info,
1020 SmallVectorImpl<DeducedTemplateArgument> &Deduced,
1022 bool PartialOrdering = false) {
1023 // C++0x [temp.deduct.type]p10:
1024 // Similarly, if P has a form that contains (T), then each parameter type
1025 // Pi of the respective parameter-type- list of P is compared with the
1026 // corresponding parameter type Ai of the corresponding parameter-type-list
1028 unsigned ArgIdx = 0, ParamIdx = 0;
1029 for (; ParamIdx != NumParams; ++ParamIdx) {
1030 // Check argument types.
1031 const PackExpansionType *Expansion
1032 = dyn_cast<PackExpansionType>(Params[ParamIdx]);
1034 // Simple case: compare the parameter and argument types at this point.
1036 // Make sure we have an argument.
1037 if (ArgIdx >= NumArgs)
1038 return Sema::TDK_MiscellaneousDeductionFailure;
1040 if (isa<PackExpansionType>(Args[ArgIdx])) {
1041 // C++0x [temp.deduct.type]p22:
1042 // If the original function parameter associated with A is a function
1043 // parameter pack and the function parameter associated with P is not
1044 // a function parameter pack, then template argument deduction fails.
1045 return Sema::TDK_MiscellaneousDeductionFailure;
1048 if (Sema::TemplateDeductionResult Result
1049 = DeduceTemplateArgumentsByTypeMatch(S, TemplateParams,
1050 Params[ParamIdx], Args[ArgIdx],
1059 // C++0x [temp.deduct.type]p10:
1060 // If the parameter-declaration corresponding to Pi is a function
1061 // parameter pack, then the type of its declarator- id is compared with
1062 // each remaining parameter type in the parameter-type-list of A. Each
1063 // comparison deduces template arguments for subsequent positions in the
1064 // template parameter packs expanded by the function parameter pack.
1066 QualType Pattern = Expansion->getPattern();
1067 PackDeductionScope PackScope(S, TemplateParams, Deduced, Info, Pattern);
1069 // A pack scope with fixed arity is not really a pack any more, so is not
1070 // a non-deduced context.
1071 if (ParamIdx + 1 == NumParams || PackScope.hasFixedArity()) {
1072 for (; ArgIdx < NumArgs && PackScope.hasNextElement(); ++ArgIdx) {
1073 // Deduce template arguments from the pattern.
1074 if (Sema::TemplateDeductionResult Result
1075 = DeduceTemplateArgumentsByTypeMatch(S, TemplateParams, Pattern,
1076 Args[ArgIdx], Info, Deduced,
1077 TDF, PartialOrdering))
1080 PackScope.nextPackElement();
1083 // C++0x [temp.deduct.type]p5:
1084 // The non-deduced contexts are:
1085 // - A function parameter pack that does not occur at the end of the
1086 // parameter-declaration-clause.
1088 // FIXME: There is no wording to say what we should do in this case. We
1089 // choose to resolve this by applying the same rule that is applied for a
1090 // function call: that is, deduce all contained packs to their
1091 // explicitly-specified values (or to <> if there is no such value).
1093 // This is seemingly-arbitrarily different from the case of a template-id
1094 // with a non-trailing pack-expansion in its arguments, which renders the
1095 // entire template-argument-list a non-deduced context.
1097 // If the parameter type contains an explicitly-specified pack that we
1098 // could not expand, skip the number of parameters notionally created
1099 // by the expansion.
1100 Optional<unsigned> NumExpansions = Expansion->getNumExpansions();
1101 if (NumExpansions && !PackScope.isPartiallyExpanded()) {
1102 for (unsigned I = 0; I != *NumExpansions && ArgIdx < NumArgs;
1104 PackScope.nextPackElement();
1108 // Build argument packs for each of the parameter packs expanded by this
1110 if (auto Result = PackScope.finish())
1114 // Make sure we don't have any extra arguments.
1115 if (ArgIdx < NumArgs)
1116 return Sema::TDK_MiscellaneousDeductionFailure;
1118 return Sema::TDK_Success;
1121 /// Determine whether the parameter has qualifiers that the argument
1122 /// lacks. Put another way, determine whether there is no way to add
1123 /// a deduced set of qualifiers to the ParamType that would result in
1124 /// its qualifiers matching those of the ArgType.
1125 static bool hasInconsistentOrSupersetQualifiersOf(QualType ParamType,
1127 Qualifiers ParamQs = ParamType.getQualifiers();
1128 Qualifiers ArgQs = ArgType.getQualifiers();
1130 if (ParamQs == ArgQs)
1133 // Mismatched (but not missing) Objective-C GC attributes.
1134 if (ParamQs.getObjCGCAttr() != ArgQs.getObjCGCAttr() &&
1135 ParamQs.hasObjCGCAttr())
1138 // Mismatched (but not missing) address spaces.
1139 if (ParamQs.getAddressSpace() != ArgQs.getAddressSpace() &&
1140 ParamQs.hasAddressSpace())
1143 // Mismatched (but not missing) Objective-C lifetime qualifiers.
1144 if (ParamQs.getObjCLifetime() != ArgQs.getObjCLifetime() &&
1145 ParamQs.hasObjCLifetime())
1148 // CVR qualifiers inconsistent or a superset.
1149 return (ParamQs.getCVRQualifiers() & ~ArgQs.getCVRQualifiers()) != 0;
1152 /// Compare types for equality with respect to possibly compatible
1153 /// function types (noreturn adjustment, implicit calling conventions). If any
1154 /// of parameter and argument is not a function, just perform type comparison.
1156 /// \param Param the template parameter type.
1158 /// \param Arg the argument type.
1159 bool Sema::isSameOrCompatibleFunctionType(CanQualType Param,
1161 const FunctionType *ParamFunction = Param->getAs<FunctionType>(),
1162 *ArgFunction = Arg->getAs<FunctionType>();
1164 // Just compare if not functions.
1165 if (!ParamFunction || !ArgFunction)
1166 return Param == Arg;
1168 // Noreturn and noexcept adjustment.
1169 QualType AdjustedParam;
1170 if (IsFunctionConversion(Param, Arg, AdjustedParam))
1171 return Arg == Context.getCanonicalType(AdjustedParam);
1173 // FIXME: Compatible calling conventions.
1175 return Param == Arg;
1178 /// Get the index of the first template parameter that was originally from the
1179 /// innermost template-parameter-list. This is 0 except when we concatenate
1180 /// the template parameter lists of a class template and a constructor template
1181 /// when forming an implicit deduction guide.
1182 static unsigned getFirstInnerIndex(FunctionTemplateDecl *FTD) {
1183 auto *Guide = dyn_cast<CXXDeductionGuideDecl>(FTD->getTemplatedDecl());
1184 if (!Guide || !Guide->isImplicit())
1186 return Guide->getDeducedTemplate()->getTemplateParameters()->size();
1189 /// Determine whether a type denotes a forwarding reference.
1190 static bool isForwardingReference(QualType Param, unsigned FirstInnerIndex) {
1191 // C++1z [temp.deduct.call]p3:
1192 // A forwarding reference is an rvalue reference to a cv-unqualified
1193 // template parameter that does not represent a template parameter of a
1195 if (auto *ParamRef = Param->getAs<RValueReferenceType>()) {
1196 if (ParamRef->getPointeeType().getQualifiers())
1198 auto *TypeParm = ParamRef->getPointeeType()->getAs<TemplateTypeParmType>();
1199 return TypeParm && TypeParm->getIndex() >= FirstInnerIndex;
1204 /// Deduce the template arguments by comparing the parameter type and
1205 /// the argument type (C++ [temp.deduct.type]).
1207 /// \param S the semantic analysis object within which we are deducing
1209 /// \param TemplateParams the template parameters that we are deducing
1211 /// \param ParamIn the parameter type
1213 /// \param ArgIn the argument type
1215 /// \param Info information about the template argument deduction itself
1217 /// \param Deduced the deduced template arguments
1219 /// \param TDF bitwise OR of the TemplateDeductionFlags bits that describe
1220 /// how template argument deduction is performed.
1222 /// \param PartialOrdering Whether we're performing template argument deduction
1223 /// in the context of partial ordering (C++0x [temp.deduct.partial]).
1225 /// \returns the result of template argument deduction so far. Note that a
1226 /// "success" result means that template argument deduction has not yet failed,
1227 /// but it may still fail, later, for other reasons.
1228 static Sema::TemplateDeductionResult
1229 DeduceTemplateArgumentsByTypeMatch(Sema &S,
1230 TemplateParameterList *TemplateParams,
1231 QualType ParamIn, QualType ArgIn,
1232 TemplateDeductionInfo &Info,
1233 SmallVectorImpl<DeducedTemplateArgument> &Deduced,
1235 bool PartialOrdering,
1236 bool DeducedFromArrayBound) {
1237 // We only want to look at the canonical types, since typedefs and
1238 // sugar are not part of template argument deduction.
1239 QualType Param = S.Context.getCanonicalType(ParamIn);
1240 QualType Arg = S.Context.getCanonicalType(ArgIn);
1242 // If the argument type is a pack expansion, look at its pattern.
1243 // This isn't explicitly called out
1244 if (const PackExpansionType *ArgExpansion
1245 = dyn_cast<PackExpansionType>(Arg))
1246 Arg = ArgExpansion->getPattern();
1248 if (PartialOrdering) {
1249 // C++11 [temp.deduct.partial]p5:
1250 // Before the partial ordering is done, certain transformations are
1251 // performed on the types used for partial ordering:
1252 // - If P is a reference type, P is replaced by the type referred to.
1253 const ReferenceType *ParamRef = Param->getAs<ReferenceType>();
1255 Param = ParamRef->getPointeeType();
1257 // - If A is a reference type, A is replaced by the type referred to.
1258 const ReferenceType *ArgRef = Arg->getAs<ReferenceType>();
1260 Arg = ArgRef->getPointeeType();
1262 if (ParamRef && ArgRef && S.Context.hasSameUnqualifiedType(Param, Arg)) {
1263 // C++11 [temp.deduct.partial]p9:
1264 // If, for a given type, deduction succeeds in both directions (i.e.,
1265 // the types are identical after the transformations above) and both
1266 // P and A were reference types [...]:
1267 // - if [one type] was an lvalue reference and [the other type] was
1268 // not, [the other type] is not considered to be at least as
1269 // specialized as [the first type]
1270 // - if [one type] is more cv-qualified than [the other type],
1271 // [the other type] is not considered to be at least as specialized
1272 // as [the first type]
1273 // Objective-C ARC adds:
1274 // - [one type] has non-trivial lifetime, [the other type] has
1275 // __unsafe_unretained lifetime, and the types are otherwise
1278 // A is "considered to be at least as specialized" as P iff deduction
1279 // succeeds, so we model this as a deduction failure. Note that
1280 // [the first type] is P and [the other type] is A here; the standard
1281 // gets this backwards.
1282 Qualifiers ParamQuals = Param.getQualifiers();
1283 Qualifiers ArgQuals = Arg.getQualifiers();
1284 if ((ParamRef->isLValueReferenceType() &&
1285 !ArgRef->isLValueReferenceType()) ||
1286 ParamQuals.isStrictSupersetOf(ArgQuals) ||
1287 (ParamQuals.hasNonTrivialObjCLifetime() &&
1288 ArgQuals.getObjCLifetime() == Qualifiers::OCL_ExplicitNone &&
1289 ParamQuals.withoutObjCLifetime() ==
1290 ArgQuals.withoutObjCLifetime())) {
1291 Info.FirstArg = TemplateArgument(ParamIn);
1292 Info.SecondArg = TemplateArgument(ArgIn);
1293 return Sema::TDK_NonDeducedMismatch;
1297 // C++11 [temp.deduct.partial]p7:
1298 // Remove any top-level cv-qualifiers:
1299 // - If P is a cv-qualified type, P is replaced by the cv-unqualified
1301 Param = Param.getUnqualifiedType();
1302 // - If A is a cv-qualified type, A is replaced by the cv-unqualified
1304 Arg = Arg.getUnqualifiedType();
1306 // C++0x [temp.deduct.call]p4 bullet 1:
1307 // - If the original P is a reference type, the deduced A (i.e., the type
1308 // referred to by the reference) can be more cv-qualified than the
1310 if (TDF & TDF_ParamWithReferenceType) {
1312 QualType UnqualParam = S.Context.getUnqualifiedArrayType(Param, Quals);
1313 Quals.setCVRQualifiers(Quals.getCVRQualifiers() &
1314 Arg.getCVRQualifiers());
1315 Param = S.Context.getQualifiedType(UnqualParam, Quals);
1318 if ((TDF & TDF_TopLevelParameterTypeList) && !Param->isFunctionType()) {
1319 // C++0x [temp.deduct.type]p10:
1320 // If P and A are function types that originated from deduction when
1321 // taking the address of a function template (14.8.2.2) or when deducing
1322 // template arguments from a function declaration (14.8.2.6) and Pi and
1323 // Ai are parameters of the top-level parameter-type-list of P and A,
1324 // respectively, Pi is adjusted if it is a forwarding reference and Ai
1325 // is an lvalue reference, in
1326 // which case the type of Pi is changed to be the template parameter
1327 // type (i.e., T&& is changed to simply T). [ Note: As a result, when
1328 // Pi is T&& and Ai is X&, the adjusted Pi will be T, causing T to be
1329 // deduced as X&. - end note ]
1330 TDF &= ~TDF_TopLevelParameterTypeList;
1331 if (isForwardingReference(Param, 0) && Arg->isLValueReferenceType())
1332 Param = Param->getPointeeType();
1336 // C++ [temp.deduct.type]p9:
1337 // A template type argument T, a template template argument TT or a
1338 // template non-type argument i can be deduced if P and A have one of
1339 // the following forms:
1343 if (const TemplateTypeParmType *TemplateTypeParm
1344 = Param->getAs<TemplateTypeParmType>()) {
1345 // Just skip any attempts to deduce from a placeholder type or a parameter
1346 // at a different depth.
1347 if (Arg->isPlaceholderType() ||
1348 Info.getDeducedDepth() != TemplateTypeParm->getDepth())
1349 return Sema::TDK_Success;
1351 unsigned Index = TemplateTypeParm->getIndex();
1352 bool RecanonicalizeArg = false;
1354 // If the argument type is an array type, move the qualifiers up to the
1355 // top level, so they can be matched with the qualifiers on the parameter.
1356 if (isa<ArrayType>(Arg)) {
1358 Arg = S.Context.getUnqualifiedArrayType(Arg, Quals);
1360 Arg = S.Context.getQualifiedType(Arg, Quals);
1361 RecanonicalizeArg = true;
1365 // The argument type can not be less qualified than the parameter
1367 if (!(TDF & TDF_IgnoreQualifiers) &&
1368 hasInconsistentOrSupersetQualifiersOf(Param, Arg)) {
1369 Info.Param = cast<TemplateTypeParmDecl>(TemplateParams->getParam(Index));
1370 Info.FirstArg = TemplateArgument(Param);
1371 Info.SecondArg = TemplateArgument(Arg);
1372 return Sema::TDK_Underqualified;
1375 // Do not match a function type with a cv-qualified type.
1376 // http://www.open-std.org/jtc1/sc22/wg21/docs/cwg_active.html#1584
1377 if (Arg->isFunctionType() && Param.hasQualifiers()) {
1378 return Sema::TDK_NonDeducedMismatch;
1381 assert(TemplateTypeParm->getDepth() == Info.getDeducedDepth() &&
1382 "saw template type parameter with wrong depth");
1383 assert(Arg != S.Context.OverloadTy && "Unresolved overloaded function");
1384 QualType DeducedType = Arg;
1386 // Remove any qualifiers on the parameter from the deduced type.
1387 // We checked the qualifiers for consistency above.
1388 Qualifiers DeducedQs = DeducedType.getQualifiers();
1389 Qualifiers ParamQs = Param.getQualifiers();
1390 DeducedQs.removeCVRQualifiers(ParamQs.getCVRQualifiers());
1391 if (ParamQs.hasObjCGCAttr())
1392 DeducedQs.removeObjCGCAttr();
1393 if (ParamQs.hasAddressSpace())
1394 DeducedQs.removeAddressSpace();
1395 if (ParamQs.hasObjCLifetime())
1396 DeducedQs.removeObjCLifetime();
1399 // If template deduction would produce a lifetime qualifier on a type
1400 // that is not a lifetime type, template argument deduction fails.
1401 if (ParamQs.hasObjCLifetime() && !DeducedType->isObjCLifetimeType() &&
1402 !DeducedType->isDependentType()) {
1403 Info.Param = cast<TemplateTypeParmDecl>(TemplateParams->getParam(Index));
1404 Info.FirstArg = TemplateArgument(Param);
1405 Info.SecondArg = TemplateArgument(Arg);
1406 return Sema::TDK_Underqualified;
1410 // If template deduction would produce an argument type with lifetime type
1411 // but no lifetime qualifier, the __strong lifetime qualifier is inferred.
1412 if (S.getLangOpts().ObjCAutoRefCount &&
1413 DeducedType->isObjCLifetimeType() &&
1414 !DeducedQs.hasObjCLifetime())
1415 DeducedQs.setObjCLifetime(Qualifiers::OCL_Strong);
1417 DeducedType = S.Context.getQualifiedType(DeducedType.getUnqualifiedType(),
1420 if (RecanonicalizeArg)
1421 DeducedType = S.Context.getCanonicalType(DeducedType);
1423 DeducedTemplateArgument NewDeduced(DeducedType, DeducedFromArrayBound);
1424 DeducedTemplateArgument Result = checkDeducedTemplateArguments(S.Context,
1427 if (Result.isNull()) {
1428 Info.Param = cast<TemplateTypeParmDecl>(TemplateParams->getParam(Index));
1429 Info.FirstArg = Deduced[Index];
1430 Info.SecondArg = NewDeduced;
1431 return Sema::TDK_Inconsistent;
1434 Deduced[Index] = Result;
1435 return Sema::TDK_Success;
1438 // Set up the template argument deduction information for a failure.
1439 Info.FirstArg = TemplateArgument(ParamIn);
1440 Info.SecondArg = TemplateArgument(ArgIn);
1442 // If the parameter is an already-substituted template parameter
1443 // pack, do nothing: we don't know which of its arguments to look
1444 // at, so we have to wait until all of the parameter packs in this
1445 // expansion have arguments.
1446 if (isa<SubstTemplateTypeParmPackType>(Param))
1447 return Sema::TDK_Success;
1449 // Check the cv-qualifiers on the parameter and argument types.
1450 CanQualType CanParam = S.Context.getCanonicalType(Param);
1451 CanQualType CanArg = S.Context.getCanonicalType(Arg);
1452 if (!(TDF & TDF_IgnoreQualifiers)) {
1453 if (TDF & TDF_ParamWithReferenceType) {
1454 if (hasInconsistentOrSupersetQualifiersOf(Param, Arg))
1455 return Sema::TDK_NonDeducedMismatch;
1456 } else if (TDF & TDF_ArgWithReferenceType) {
1457 // C++ [temp.deduct.conv]p4:
1458 // If the original A is a reference type, A can be more cv-qualified
1459 // than the deduced A
1460 if (!Arg.getQualifiers().compatiblyIncludes(Param.getQualifiers()))
1461 return Sema::TDK_NonDeducedMismatch;
1463 // Strip out all extra qualifiers from the argument to figure out the
1464 // type we're converting to, prior to the qualification conversion.
1466 Arg = S.Context.getUnqualifiedArrayType(Arg, Quals);
1467 Arg = S.Context.getQualifiedType(Arg, Param.getQualifiers());
1468 } else if (!IsPossiblyOpaquelyQualifiedType(Param)) {
1469 if (Param.getCVRQualifiers() != Arg.getCVRQualifiers())
1470 return Sema::TDK_NonDeducedMismatch;
1473 // If the parameter type is not dependent, there is nothing to deduce.
1474 if (!Param->isDependentType()) {
1475 if (!(TDF & TDF_SkipNonDependent)) {
1477 (TDF & TDF_AllowCompatibleFunctionType)
1478 ? !S.isSameOrCompatibleFunctionType(CanParam, CanArg)
1481 return Sema::TDK_NonDeducedMismatch;
1484 return Sema::TDK_Success;
1486 } else if (!Param->isDependentType()) {
1487 CanQualType ParamUnqualType = CanParam.getUnqualifiedType(),
1488 ArgUnqualType = CanArg.getUnqualifiedType();
1490 (TDF & TDF_AllowCompatibleFunctionType)
1491 ? S.isSameOrCompatibleFunctionType(ParamUnqualType, ArgUnqualType)
1492 : ParamUnqualType == ArgUnqualType;
1494 return Sema::TDK_Success;
1497 switch (Param->getTypeClass()) {
1498 // Non-canonical types cannot appear here.
1499 #define NON_CANONICAL_TYPE(Class, Base) \
1500 case Type::Class: llvm_unreachable("deducing non-canonical type: " #Class);
1501 #define TYPE(Class, Base)
1502 #include "clang/AST/TypeNodes.inc"
1504 case Type::TemplateTypeParm:
1505 case Type::SubstTemplateTypeParmPack:
1506 llvm_unreachable("Type nodes handled above");
1508 // These types cannot be dependent, so simply check whether the types are
1511 case Type::VariableArray:
1513 case Type::FunctionNoProto:
1516 case Type::ObjCObject:
1517 case Type::ObjCInterface:
1518 case Type::ObjCObjectPointer:
1520 if (TDF & TDF_SkipNonDependent)
1521 return Sema::TDK_Success;
1523 if (TDF & TDF_IgnoreQualifiers) {
1524 Param = Param.getUnqualifiedType();
1525 Arg = Arg.getUnqualifiedType();
1528 return Param == Arg? Sema::TDK_Success : Sema::TDK_NonDeducedMismatch;
1530 // _Complex T [placeholder extension]
1532 if (const ComplexType *ComplexArg = Arg->getAs<ComplexType>())
1533 return DeduceTemplateArgumentsByTypeMatch(S, TemplateParams,
1534 cast<ComplexType>(Param)->getElementType(),
1535 ComplexArg->getElementType(),
1536 Info, Deduced, TDF);
1538 return Sema::TDK_NonDeducedMismatch;
1540 // _Atomic T [extension]
1542 if (const AtomicType *AtomicArg = Arg->getAs<AtomicType>())
1543 return DeduceTemplateArgumentsByTypeMatch(S, TemplateParams,
1544 cast<AtomicType>(Param)->getValueType(),
1545 AtomicArg->getValueType(),
1546 Info, Deduced, TDF);
1548 return Sema::TDK_NonDeducedMismatch;
1551 case Type::Pointer: {
1552 QualType PointeeType;
1553 if (const PointerType *PointerArg = Arg->getAs<PointerType>()) {
1554 PointeeType = PointerArg->getPointeeType();
1555 } else if (const ObjCObjectPointerType *PointerArg
1556 = Arg->getAs<ObjCObjectPointerType>()) {
1557 PointeeType = PointerArg->getPointeeType();
1559 return Sema::TDK_NonDeducedMismatch;
1562 unsigned SubTDF = TDF & (TDF_IgnoreQualifiers | TDF_DerivedClass);
1563 return DeduceTemplateArgumentsByTypeMatch(S, TemplateParams,
1564 cast<PointerType>(Param)->getPointeeType(),
1566 Info, Deduced, SubTDF);
1570 case Type::LValueReference: {
1571 const LValueReferenceType *ReferenceArg =
1572 Arg->getAs<LValueReferenceType>();
1574 return Sema::TDK_NonDeducedMismatch;
1576 return DeduceTemplateArgumentsByTypeMatch(S, TemplateParams,
1577 cast<LValueReferenceType>(Param)->getPointeeType(),
1578 ReferenceArg->getPointeeType(), Info, Deduced, 0);
1582 case Type::RValueReference: {
1583 const RValueReferenceType *ReferenceArg =
1584 Arg->getAs<RValueReferenceType>();
1586 return Sema::TDK_NonDeducedMismatch;
1588 return DeduceTemplateArgumentsByTypeMatch(S, TemplateParams,
1589 cast<RValueReferenceType>(Param)->getPointeeType(),
1590 ReferenceArg->getPointeeType(),
1594 // T [] (implied, but not stated explicitly)
1595 case Type::IncompleteArray: {
1596 const IncompleteArrayType *IncompleteArrayArg =
1597 S.Context.getAsIncompleteArrayType(Arg);
1598 if (!IncompleteArrayArg)
1599 return Sema::TDK_NonDeducedMismatch;
1601 unsigned SubTDF = TDF & TDF_IgnoreQualifiers;
1602 return DeduceTemplateArgumentsByTypeMatch(S, TemplateParams,
1603 S.Context.getAsIncompleteArrayType(Param)->getElementType(),
1604 IncompleteArrayArg->getElementType(),
1605 Info, Deduced, SubTDF);
1608 // T [integer-constant]
1609 case Type::ConstantArray: {
1610 const ConstantArrayType *ConstantArrayArg =
1611 S.Context.getAsConstantArrayType(Arg);
1612 if (!ConstantArrayArg)
1613 return Sema::TDK_NonDeducedMismatch;
1615 const ConstantArrayType *ConstantArrayParm =
1616 S.Context.getAsConstantArrayType(Param);
1617 if (ConstantArrayArg->getSize() != ConstantArrayParm->getSize())
1618 return Sema::TDK_NonDeducedMismatch;
1620 unsigned SubTDF = TDF & TDF_IgnoreQualifiers;
1621 return DeduceTemplateArgumentsByTypeMatch(S, TemplateParams,
1622 ConstantArrayParm->getElementType(),
1623 ConstantArrayArg->getElementType(),
1624 Info, Deduced, SubTDF);
1628 case Type::DependentSizedArray: {
1629 const ArrayType *ArrayArg = S.Context.getAsArrayType(Arg);
1631 return Sema::TDK_NonDeducedMismatch;
1633 unsigned SubTDF = TDF & TDF_IgnoreQualifiers;
1635 // Check the element type of the arrays
1636 const DependentSizedArrayType *DependentArrayParm
1637 = S.Context.getAsDependentSizedArrayType(Param);
1638 if (Sema::TemplateDeductionResult Result
1639 = DeduceTemplateArgumentsByTypeMatch(S, TemplateParams,
1640 DependentArrayParm->getElementType(),
1641 ArrayArg->getElementType(),
1642 Info, Deduced, SubTDF))
1645 // Determine the array bound is something we can deduce.
1646 NonTypeTemplateParmDecl *NTTP
1647 = getDeducedParameterFromExpr(Info, DependentArrayParm->getSizeExpr());
1649 return Sema::TDK_Success;
1651 // We can perform template argument deduction for the given non-type
1652 // template parameter.
1653 assert(NTTP->getDepth() == Info.getDeducedDepth() &&
1654 "saw non-type template parameter with wrong depth");
1655 if (const ConstantArrayType *ConstantArrayArg
1656 = dyn_cast<ConstantArrayType>(ArrayArg)) {
1657 llvm::APSInt Size(ConstantArrayArg->getSize());
1658 return DeduceNonTypeTemplateArgument(S, TemplateParams, NTTP, Size,
1659 S.Context.getSizeType(),
1660 /*ArrayBound=*/true,
1663 if (const DependentSizedArrayType *DependentArrayArg
1664 = dyn_cast<DependentSizedArrayType>(ArrayArg))
1665 if (DependentArrayArg->getSizeExpr())
1666 return DeduceNonTypeTemplateArgument(S, TemplateParams, NTTP,
1667 DependentArrayArg->getSizeExpr(),
1670 // Incomplete type does not match a dependently-sized array type
1671 return Sema::TDK_NonDeducedMismatch;
1677 case Type::FunctionProto: {
1678 unsigned SubTDF = TDF & TDF_TopLevelParameterTypeList;
1679 const FunctionProtoType *FunctionProtoArg =
1680 dyn_cast<FunctionProtoType>(Arg);
1681 if (!FunctionProtoArg)
1682 return Sema::TDK_NonDeducedMismatch;
1684 const FunctionProtoType *FunctionProtoParam =
1685 cast<FunctionProtoType>(Param);
1687 if (FunctionProtoParam->getMethodQuals()
1688 != FunctionProtoArg->getMethodQuals() ||
1689 FunctionProtoParam->getRefQualifier()
1690 != FunctionProtoArg->getRefQualifier() ||
1691 FunctionProtoParam->isVariadic() != FunctionProtoArg->isVariadic())
1692 return Sema::TDK_NonDeducedMismatch;
1694 // Check return types.
1695 if (auto Result = DeduceTemplateArgumentsByTypeMatch(
1696 S, TemplateParams, FunctionProtoParam->getReturnType(),
1697 FunctionProtoArg->getReturnType(), Info, Deduced, 0))
1700 // Check parameter types.
1701 if (auto Result = DeduceTemplateArguments(
1702 S, TemplateParams, FunctionProtoParam->param_type_begin(),
1703 FunctionProtoParam->getNumParams(),
1704 FunctionProtoArg->param_type_begin(),
1705 FunctionProtoArg->getNumParams(), Info, Deduced, SubTDF))
1708 if (TDF & TDF_AllowCompatibleFunctionType)
1709 return Sema::TDK_Success;
1711 // FIXME: Per core-2016/10/1019 (no corresponding core issue yet), permit
1712 // deducing through the noexcept-specifier if it's part of the canonical
1713 // type. libstdc++ relies on this.
1714 Expr *NoexceptExpr = FunctionProtoParam->getNoexceptExpr();
1715 if (NonTypeTemplateParmDecl *NTTP =
1716 NoexceptExpr ? getDeducedParameterFromExpr(Info, NoexceptExpr)
1718 assert(NTTP->getDepth() == Info.getDeducedDepth() &&
1719 "saw non-type template parameter with wrong depth");
1721 llvm::APSInt Noexcept(1);
1722 switch (FunctionProtoArg->canThrow()) {
1728 // We give E in noexcept(E) the "deduced from array bound" treatment.
1729 // FIXME: Should we?
1730 return DeduceNonTypeTemplateArgument(
1731 S, TemplateParams, NTTP, Noexcept, S.Context.BoolTy,
1732 /*ArrayBound*/true, Info, Deduced);
1735 if (Expr *ArgNoexceptExpr = FunctionProtoArg->getNoexceptExpr())
1736 return DeduceNonTypeTemplateArgument(
1737 S, TemplateParams, NTTP, ArgNoexceptExpr, Info, Deduced);
1738 // Can't deduce anything from throw(T...).
1742 // FIXME: Detect non-deduced exception specification mismatches?
1744 // Careful about [temp.deduct.call] and [temp.deduct.conv], which allow
1745 // top-level differences in noexcept-specifications.
1747 return Sema::TDK_Success;
1750 case Type::InjectedClassName:
1751 // Treat a template's injected-class-name as if the template
1752 // specialization type had been used.
1753 Param = cast<InjectedClassNameType>(Param)
1754 ->getInjectedSpecializationType();
1755 assert(isa<TemplateSpecializationType>(Param) &&
1756 "injected class name is not a template specialization type");
1759 // template-name<T> (where template-name refers to a class template)
1764 case Type::TemplateSpecialization: {
1765 const TemplateSpecializationType *SpecParam =
1766 cast<TemplateSpecializationType>(Param);
1768 // When Arg cannot be a derived class, we can just try to deduce template
1769 // arguments from the template-id.
1770 const RecordType *RecordT = Arg->getAs<RecordType>();
1771 if (!(TDF & TDF_DerivedClass) || !RecordT)
1772 return DeduceTemplateArguments(S, TemplateParams, SpecParam, Arg, Info,
1775 SmallVector<DeducedTemplateArgument, 8> DeducedOrig(Deduced.begin(),
1778 Sema::TemplateDeductionResult Result = DeduceTemplateArguments(
1779 S, TemplateParams, SpecParam, Arg, Info, Deduced);
1781 if (Result == Sema::TDK_Success)
1784 // We cannot inspect base classes as part of deduction when the type
1785 // is incomplete, so either instantiate any templates necessary to
1786 // complete the type, or skip over it if it cannot be completed.
1787 if (!S.isCompleteType(Info.getLocation(), Arg))
1790 // C++14 [temp.deduct.call] p4b3:
1791 // If P is a class and P has the form simple-template-id, then the
1792 // transformed A can be a derived class of the deduced A. Likewise if
1793 // P is a pointer to a class of the form simple-template-id, the
1794 // transformed A can be a pointer to a derived class pointed to by the
1797 // These alternatives are considered only if type deduction would
1798 // otherwise fail. If they yield more than one possible deduced A, the
1799 // type deduction fails.
1801 // Reset the incorrectly deduced argument from above.
1802 Deduced = DeducedOrig;
1804 // Use data recursion to crawl through the list of base classes.
1805 // Visited contains the set of nodes we have already visited, while
1806 // ToVisit is our stack of records that we still need to visit.
1807 llvm::SmallPtrSet<const RecordType *, 8> Visited;
1808 SmallVector<const RecordType *, 8> ToVisit;
1809 ToVisit.push_back(RecordT);
1810 bool Successful = false;
1811 SmallVector<DeducedTemplateArgument, 8> SuccessfulDeduced;
1812 while (!ToVisit.empty()) {
1813 // Retrieve the next class in the inheritance hierarchy.
1814 const RecordType *NextT = ToVisit.pop_back_val();
1816 // If we have already seen this type, skip it.
1817 if (!Visited.insert(NextT).second)
1820 // If this is a base class, try to perform template argument
1821 // deduction from it.
1822 if (NextT != RecordT) {
1823 TemplateDeductionInfo BaseInfo(TemplateDeductionInfo::ForBase, Info);
1824 Sema::TemplateDeductionResult BaseResult =
1825 DeduceTemplateArguments(S, TemplateParams, SpecParam,
1826 QualType(NextT, 0), BaseInfo, Deduced);
1828 // If template argument deduction for this base was successful,
1829 // note that we had some success. Otherwise, ignore any deductions
1830 // from this base class.
1831 if (BaseResult == Sema::TDK_Success) {
1832 // If we've already seen some success, then deduction fails due to
1833 // an ambiguity (temp.deduct.call p5).
1835 return Sema::TDK_MiscellaneousDeductionFailure;
1838 std::swap(SuccessfulDeduced, Deduced);
1840 Info.Param = BaseInfo.Param;
1841 Info.FirstArg = BaseInfo.FirstArg;
1842 Info.SecondArg = BaseInfo.SecondArg;
1845 Deduced = DeducedOrig;
1848 // Visit base classes
1849 CXXRecordDecl *Next = cast<CXXRecordDecl>(NextT->getDecl());
1850 for (const auto &Base : Next->bases()) {
1851 assert(Base.getType()->isRecordType() &&
1852 "Base class that isn't a record?");
1853 ToVisit.push_back(Base.getType()->getAs<RecordType>());
1858 std::swap(SuccessfulDeduced, Deduced);
1859 return Sema::TDK_Success;
1869 // type (type::*)(T)
1874 case Type::MemberPointer: {
1875 const MemberPointerType *MemPtrParam = cast<MemberPointerType>(Param);
1876 const MemberPointerType *MemPtrArg = dyn_cast<MemberPointerType>(Arg);
1878 return Sema::TDK_NonDeducedMismatch;
1880 QualType ParamPointeeType = MemPtrParam->getPointeeType();
1881 if (ParamPointeeType->isFunctionType())
1882 S.adjustMemberFunctionCC(ParamPointeeType, /*IsStatic=*/true,
1883 /*IsCtorOrDtor=*/false, Info.getLocation());
1884 QualType ArgPointeeType = MemPtrArg->getPointeeType();
1885 if (ArgPointeeType->isFunctionType())
1886 S.adjustMemberFunctionCC(ArgPointeeType, /*IsStatic=*/true,
1887 /*IsCtorOrDtor=*/false, Info.getLocation());
1889 if (Sema::TemplateDeductionResult Result
1890 = DeduceTemplateArgumentsByTypeMatch(S, TemplateParams,
1894 TDF & TDF_IgnoreQualifiers))
1897 return DeduceTemplateArgumentsByTypeMatch(S, TemplateParams,
1898 QualType(MemPtrParam->getClass(), 0),
1899 QualType(MemPtrArg->getClass(), 0),
1901 TDF & TDF_IgnoreQualifiers);
1904 // (clang extension)
1909 case Type::BlockPointer: {
1910 const BlockPointerType *BlockPtrParam = cast<BlockPointerType>(Param);
1911 const BlockPointerType *BlockPtrArg = dyn_cast<BlockPointerType>(Arg);
1914 return Sema::TDK_NonDeducedMismatch;
1916 return DeduceTemplateArgumentsByTypeMatch(S, TemplateParams,
1917 BlockPtrParam->getPointeeType(),
1918 BlockPtrArg->getPointeeType(),
1922 // (clang extension)
1924 // T __attribute__(((ext_vector_type(<integral constant>))))
1925 case Type::ExtVector: {
1926 const ExtVectorType *VectorParam = cast<ExtVectorType>(Param);
1927 if (const ExtVectorType *VectorArg = dyn_cast<ExtVectorType>(Arg)) {
1928 // Make sure that the vectors have the same number of elements.
1929 if (VectorParam->getNumElements() != VectorArg->getNumElements())
1930 return Sema::TDK_NonDeducedMismatch;
1932 // Perform deduction on the element types.
1933 return DeduceTemplateArgumentsByTypeMatch(S, TemplateParams,
1934 VectorParam->getElementType(),
1935 VectorArg->getElementType(),
1936 Info, Deduced, TDF);
1939 if (const DependentSizedExtVectorType *VectorArg
1940 = dyn_cast<DependentSizedExtVectorType>(Arg)) {
1941 // We can't check the number of elements, since the argument has a
1942 // dependent number of elements. This can only occur during partial
1945 // Perform deduction on the element types.
1946 return DeduceTemplateArgumentsByTypeMatch(S, TemplateParams,
1947 VectorParam->getElementType(),
1948 VectorArg->getElementType(),
1949 Info, Deduced, TDF);
1952 return Sema::TDK_NonDeducedMismatch;
1955 case Type::DependentVector: {
1956 const auto *VectorParam = cast<DependentVectorType>(Param);
1958 if (const auto *VectorArg = dyn_cast<VectorType>(Arg)) {
1959 // Perform deduction on the element types.
1960 if (Sema::TemplateDeductionResult Result =
1961 DeduceTemplateArgumentsByTypeMatch(
1962 S, TemplateParams, VectorParam->getElementType(),
1963 VectorArg->getElementType(), Info, Deduced, TDF))
1966 // Perform deduction on the vector size, if we can.
1967 NonTypeTemplateParmDecl *NTTP =
1968 getDeducedParameterFromExpr(Info, VectorParam->getSizeExpr());
1970 return Sema::TDK_Success;
1972 llvm::APSInt ArgSize(S.Context.getTypeSize(S.Context.IntTy), false);
1973 ArgSize = VectorArg->getNumElements();
1974 // Note that we use the "array bound" rules here; just like in that
1975 // case, we don't have any particular type for the vector size, but
1976 // we can provide one if necessary.
1977 return DeduceNonTypeTemplateArgument(S, TemplateParams, NTTP, ArgSize,
1978 S.Context.UnsignedIntTy, true,
1982 if (const auto *VectorArg = dyn_cast<DependentVectorType>(Arg)) {
1983 // Perform deduction on the element types.
1984 if (Sema::TemplateDeductionResult Result =
1985 DeduceTemplateArgumentsByTypeMatch(
1986 S, TemplateParams, VectorParam->getElementType(),
1987 VectorArg->getElementType(), Info, Deduced, TDF))
1990 // Perform deduction on the vector size, if we can.
1991 NonTypeTemplateParmDecl *NTTP = getDeducedParameterFromExpr(
1992 Info, VectorParam->getSizeExpr());
1994 return Sema::TDK_Success;
1996 return DeduceNonTypeTemplateArgument(
1997 S, TemplateParams, NTTP, VectorArg->getSizeExpr(), Info, Deduced);
2000 return Sema::TDK_NonDeducedMismatch;
2003 // (clang extension)
2005 // T __attribute__(((ext_vector_type(N))))
2006 case Type::DependentSizedExtVector: {
2007 const DependentSizedExtVectorType *VectorParam
2008 = cast<DependentSizedExtVectorType>(Param);
2010 if (const ExtVectorType *VectorArg = dyn_cast<ExtVectorType>(Arg)) {
2011 // Perform deduction on the element types.
2012 if (Sema::TemplateDeductionResult Result
2013 = DeduceTemplateArgumentsByTypeMatch(S, TemplateParams,
2014 VectorParam->getElementType(),
2015 VectorArg->getElementType(),
2016 Info, Deduced, TDF))
2019 // Perform deduction on the vector size, if we can.
2020 NonTypeTemplateParmDecl *NTTP
2021 = getDeducedParameterFromExpr(Info, VectorParam->getSizeExpr());
2023 return Sema::TDK_Success;
2025 llvm::APSInt ArgSize(S.Context.getTypeSize(S.Context.IntTy), false);
2026 ArgSize = VectorArg->getNumElements();
2027 // Note that we use the "array bound" rules here; just like in that
2028 // case, we don't have any particular type for the vector size, but
2029 // we can provide one if necessary.
2030 return DeduceNonTypeTemplateArgument(S, TemplateParams, NTTP, ArgSize,
2031 S.Context.IntTy, true, Info,
2035 if (const DependentSizedExtVectorType *VectorArg
2036 = dyn_cast<DependentSizedExtVectorType>(Arg)) {
2037 // Perform deduction on the element types.
2038 if (Sema::TemplateDeductionResult Result
2039 = DeduceTemplateArgumentsByTypeMatch(S, TemplateParams,
2040 VectorParam->getElementType(),
2041 VectorArg->getElementType(),
2042 Info, Deduced, TDF))
2045 // Perform deduction on the vector size, if we can.
2046 NonTypeTemplateParmDecl *NTTP
2047 = getDeducedParameterFromExpr(Info, VectorParam->getSizeExpr());
2049 return Sema::TDK_Success;
2051 return DeduceNonTypeTemplateArgument(S, TemplateParams, NTTP,
2052 VectorArg->getSizeExpr(),
2056 return Sema::TDK_NonDeducedMismatch;
2059 // (clang extension)
2061 // T __attribute__((matrix_type(<integral constant>,
2062 // <integral constant>)))
2063 case Type::ConstantMatrix: {
2064 const ConstantMatrixType *MatrixArg = dyn_cast<ConstantMatrixType>(Arg);
2066 return Sema::TDK_NonDeducedMismatch;
2068 const ConstantMatrixType *MatrixParam = cast<ConstantMatrixType>(Param);
2069 // Check that the dimensions are the same
2070 if (MatrixParam->getNumRows() != MatrixArg->getNumRows() ||
2071 MatrixParam->getNumColumns() != MatrixArg->getNumColumns()) {
2072 return Sema::TDK_NonDeducedMismatch;
2074 // Perform deduction on element types.
2075 return DeduceTemplateArgumentsByTypeMatch(
2076 S, TemplateParams, MatrixParam->getElementType(),
2077 MatrixArg->getElementType(), Info, Deduced, TDF);
2080 case Type::DependentSizedMatrix: {
2081 const MatrixType *MatrixArg = dyn_cast<MatrixType>(Arg);
2083 return Sema::TDK_NonDeducedMismatch;
2085 // Check the element type of the matrixes.
2086 const DependentSizedMatrixType *MatrixParam =
2087 cast<DependentSizedMatrixType>(Param);
2088 if (Sema::TemplateDeductionResult Result =
2089 DeduceTemplateArgumentsByTypeMatch(
2090 S, TemplateParams, MatrixParam->getElementType(),
2091 MatrixArg->getElementType(), Info, Deduced, TDF))
2094 // Try to deduce a matrix dimension.
2095 auto DeduceMatrixArg =
2096 [&S, &Info, &Deduced, &TemplateParams](
2097 Expr *ParamExpr, const MatrixType *Arg,
2098 unsigned (ConstantMatrixType::*GetArgDimension)() const,
2099 Expr *(DependentSizedMatrixType::*GetArgDimensionExpr)() const) {
2100 const auto *ArgConstMatrix = dyn_cast<ConstantMatrixType>(Arg);
2101 const auto *ArgDepMatrix = dyn_cast<DependentSizedMatrixType>(Arg);
2102 if (!ParamExpr->isValueDependent()) {
2103 llvm::APSInt ParamConst(
2104 S.Context.getTypeSize(S.Context.getSizeType()));
2105 if (!ParamExpr->isIntegerConstantExpr(ParamConst, S.Context))
2106 return Sema::TDK_NonDeducedMismatch;
2108 if (ArgConstMatrix) {
2109 if ((ArgConstMatrix->*GetArgDimension)() == ParamConst)
2110 return Sema::TDK_Success;
2111 return Sema::TDK_NonDeducedMismatch;
2114 Expr *ArgExpr = (ArgDepMatrix->*GetArgDimensionExpr)();
2115 llvm::APSInt ArgConst(
2116 S.Context.getTypeSize(S.Context.getSizeType()));
2117 if (!ArgExpr->isValueDependent() &&
2118 ArgExpr->isIntegerConstantExpr(ArgConst, S.Context) &&
2119 ArgConst == ParamConst)
2120 return Sema::TDK_Success;
2121 return Sema::TDK_NonDeducedMismatch;
2124 NonTypeTemplateParmDecl *NTTP =
2125 getDeducedParameterFromExpr(Info, ParamExpr);
2127 return Sema::TDK_Success;
2129 if (ArgConstMatrix) {
2130 llvm::APSInt ArgConst(
2131 S.Context.getTypeSize(S.Context.getSizeType()));
2132 ArgConst = (ArgConstMatrix->*GetArgDimension)();
2133 return DeduceNonTypeTemplateArgument(
2134 S, TemplateParams, NTTP, ArgConst, S.Context.getSizeType(),
2135 /*ArrayBound=*/true, Info, Deduced);
2138 return DeduceNonTypeTemplateArgument(
2139 S, TemplateParams, NTTP, (ArgDepMatrix->*GetArgDimensionExpr)(),
2143 auto Result = DeduceMatrixArg(MatrixParam->getRowExpr(), MatrixArg,
2144 &ConstantMatrixType::getNumRows,
2145 &DependentSizedMatrixType::getRowExpr);
2149 return DeduceMatrixArg(MatrixParam->getColumnExpr(), MatrixArg,
2150 &ConstantMatrixType::getNumColumns,
2151 &DependentSizedMatrixType::getColumnExpr);
2154 // (clang extension)
2156 // T __attribute__(((address_space(N))))
2157 case Type::DependentAddressSpace: {
2158 const DependentAddressSpaceType *AddressSpaceParam =
2159 cast<DependentAddressSpaceType>(Param);
2161 if (const DependentAddressSpaceType *AddressSpaceArg =
2162 dyn_cast<DependentAddressSpaceType>(Arg)) {
2163 // Perform deduction on the pointer type.
2164 if (Sema::TemplateDeductionResult Result =
2165 DeduceTemplateArgumentsByTypeMatch(
2166 S, TemplateParams, AddressSpaceParam->getPointeeType(),
2167 AddressSpaceArg->getPointeeType(), Info, Deduced, TDF))
2170 // Perform deduction on the address space, if we can.
2171 NonTypeTemplateParmDecl *NTTP = getDeducedParameterFromExpr(
2172 Info, AddressSpaceParam->getAddrSpaceExpr());
2174 return Sema::TDK_Success;
2176 return DeduceNonTypeTemplateArgument(
2177 S, TemplateParams, NTTP, AddressSpaceArg->getAddrSpaceExpr(), Info,
2181 if (isTargetAddressSpace(Arg.getAddressSpace())) {
2182 llvm::APSInt ArgAddressSpace(S.Context.getTypeSize(S.Context.IntTy),
2184 ArgAddressSpace = toTargetAddressSpace(Arg.getAddressSpace());
2186 // Perform deduction on the pointer types.
2187 if (Sema::TemplateDeductionResult Result =
2188 DeduceTemplateArgumentsByTypeMatch(
2189 S, TemplateParams, AddressSpaceParam->getPointeeType(),
2190 S.Context.removeAddrSpaceQualType(Arg), Info, Deduced, TDF))
2193 // Perform deduction on the address space, if we can.
2194 NonTypeTemplateParmDecl *NTTP = getDeducedParameterFromExpr(
2195 Info, AddressSpaceParam->getAddrSpaceExpr());
2197 return Sema::TDK_Success;
2199 return DeduceNonTypeTemplateArgument(S, TemplateParams, NTTP,
2200 ArgAddressSpace, S.Context.IntTy,
2201 true, Info, Deduced);
2204 return Sema::TDK_NonDeducedMismatch;
2206 case Type::DependentExtInt: {
2207 const auto *IntParam = cast<DependentExtIntType>(Param);
2209 if (const auto *IntArg = dyn_cast<ExtIntType>(Arg)){
2210 if (IntParam->isUnsigned() != IntArg->isUnsigned())
2211 return Sema::TDK_NonDeducedMismatch;
2213 NonTypeTemplateParmDecl *NTTP =
2214 getDeducedParameterFromExpr(Info, IntParam->getNumBitsExpr());
2216 return Sema::TDK_Success;
2218 llvm::APSInt ArgSize(S.Context.getTypeSize(S.Context.IntTy), false);
2219 ArgSize = IntArg->getNumBits();
2221 return DeduceNonTypeTemplateArgument(S, TemplateParams, NTTP, ArgSize,
2222 S.Context.IntTy, true, Info,
2226 if (const auto *IntArg = dyn_cast<DependentExtIntType>(Arg)) {
2227 if (IntParam->isUnsigned() != IntArg->isUnsigned())
2228 return Sema::TDK_NonDeducedMismatch;
2229 return Sema::TDK_Success;
2231 return Sema::TDK_NonDeducedMismatch;
2234 case Type::TypeOfExpr:
2236 case Type::DependentName:
2237 case Type::UnresolvedUsing:
2238 case Type::Decltype:
2239 case Type::UnaryTransform:
2241 case Type::DeducedTemplateSpecialization:
2242 case Type::DependentTemplateSpecialization:
2243 case Type::PackExpansion:
2245 // No template argument deduction for these types
2246 return Sema::TDK_Success;
2249 llvm_unreachable("Invalid Type Class!");
2252 static Sema::TemplateDeductionResult
2253 DeduceTemplateArguments(Sema &S,
2254 TemplateParameterList *TemplateParams,
2255 const TemplateArgument &Param,
2256 TemplateArgument Arg,
2257 TemplateDeductionInfo &Info,
2258 SmallVectorImpl<DeducedTemplateArgument> &Deduced) {
2259 // If the template argument is a pack expansion, perform template argument
2260 // deduction against the pattern of that expansion. This only occurs during
2261 // partial ordering.
2262 if (Arg.isPackExpansion())
2263 Arg = Arg.getPackExpansionPattern();
2265 switch (Param.getKind()) {
2266 case TemplateArgument::Null:
2267 llvm_unreachable("Null template argument in parameter list");
2269 case TemplateArgument::Type:
2270 if (Arg.getKind() == TemplateArgument::Type)
2271 return DeduceTemplateArgumentsByTypeMatch(S, TemplateParams,
2275 Info.FirstArg = Param;
2276 Info.SecondArg = Arg;
2277 return Sema::TDK_NonDeducedMismatch;
2279 case TemplateArgument::Template:
2280 if (Arg.getKind() == TemplateArgument::Template)
2281 return DeduceTemplateArguments(S, TemplateParams,
2282 Param.getAsTemplate(),
2283 Arg.getAsTemplate(), Info, Deduced);
2284 Info.FirstArg = Param;
2285 Info.SecondArg = Arg;
2286 return Sema::TDK_NonDeducedMismatch;
2288 case TemplateArgument::TemplateExpansion:
2289 llvm_unreachable("caller should handle pack expansions");
2291 case TemplateArgument::Declaration:
2292 if (Arg.getKind() == TemplateArgument::Declaration &&
2293 isSameDeclaration(Param.getAsDecl(), Arg.getAsDecl()))
2294 return Sema::TDK_Success;
2296 Info.FirstArg = Param;
2297 Info.SecondArg = Arg;
2298 return Sema::TDK_NonDeducedMismatch;
2300 case TemplateArgument::NullPtr:
2301 if (Arg.getKind() == TemplateArgument::NullPtr &&
2302 S.Context.hasSameType(Param.getNullPtrType(), Arg.getNullPtrType()))
2303 return Sema::TDK_Success;
2305 Info.FirstArg = Param;
2306 Info.SecondArg = Arg;
2307 return Sema::TDK_NonDeducedMismatch;
2309 case TemplateArgument::Integral:
2310 if (Arg.getKind() == TemplateArgument::Integral) {
2311 if (hasSameExtendedValue(Param.getAsIntegral(), Arg.getAsIntegral()))
2312 return Sema::TDK_Success;
2314 Info.FirstArg = Param;
2315 Info.SecondArg = Arg;
2316 return Sema::TDK_NonDeducedMismatch;
2319 if (Arg.getKind() == TemplateArgument::Expression) {
2320 Info.FirstArg = Param;
2321 Info.SecondArg = Arg;
2322 return Sema::TDK_NonDeducedMismatch;
2325 Info.FirstArg = Param;
2326 Info.SecondArg = Arg;
2327 return Sema::TDK_NonDeducedMismatch;
2329 case TemplateArgument::Expression:
2330 if (NonTypeTemplateParmDecl *NTTP
2331 = getDeducedParameterFromExpr(Info, Param.getAsExpr())) {
2332 if (Arg.getKind() == TemplateArgument::Integral)
2333 return DeduceNonTypeTemplateArgument(S, TemplateParams, NTTP,
2334 Arg.getAsIntegral(),
2335 Arg.getIntegralType(),
2336 /*ArrayBound=*/false,
2338 if (Arg.getKind() == TemplateArgument::NullPtr)
2339 return DeduceNullPtrTemplateArgument(S, TemplateParams, NTTP,
2340 Arg.getNullPtrType(),
2342 if (Arg.getKind() == TemplateArgument::Expression)
2343 return DeduceNonTypeTemplateArgument(S, TemplateParams, NTTP,
2344 Arg.getAsExpr(), Info, Deduced);
2345 if (Arg.getKind() == TemplateArgument::Declaration)
2346 return DeduceNonTypeTemplateArgument(S, TemplateParams, NTTP,
2348 Arg.getParamTypeForDecl(),
2351 Info.FirstArg = Param;
2352 Info.SecondArg = Arg;
2353 return Sema::TDK_NonDeducedMismatch;
2356 // Can't deduce anything, but that's okay.
2357 return Sema::TDK_Success;
2359 case TemplateArgument::Pack:
2360 llvm_unreachable("Argument packs should be expanded by the caller!");
2363 llvm_unreachable("Invalid TemplateArgument Kind!");
2366 /// Determine whether there is a template argument to be used for
2369 /// This routine "expands" argument packs in-place, overriding its input
2370 /// parameters so that \c Args[ArgIdx] will be the available template argument.
2372 /// \returns true if there is another template argument (which will be at
2373 /// \c Args[ArgIdx]), false otherwise.
2374 static bool hasTemplateArgumentForDeduction(ArrayRef<TemplateArgument> &Args,
2376 if (ArgIdx == Args.size())
2379 const TemplateArgument &Arg = Args[ArgIdx];
2380 if (Arg.getKind() != TemplateArgument::Pack)
2383 assert(ArgIdx == Args.size() - 1 && "Pack not at the end of argument list?");
2384 Args = Arg.pack_elements();
2386 return ArgIdx < Args.size();
2389 /// Determine whether the given set of template arguments has a pack
2390 /// expansion that is not the last template argument.
2391 static bool hasPackExpansionBeforeEnd(ArrayRef<TemplateArgument> Args) {
2392 bool FoundPackExpansion = false;
2393 for (const auto &A : Args) {
2394 if (FoundPackExpansion)
2397 if (A.getKind() == TemplateArgument::Pack)
2398 return hasPackExpansionBeforeEnd(A.pack_elements());
2400 // FIXME: If this is a fixed-arity pack expansion from an outer level of
2401 // templates, it should not be treated as a pack expansion.
2402 if (A.isPackExpansion())
2403 FoundPackExpansion = true;
2409 static Sema::TemplateDeductionResult
2410 DeduceTemplateArguments(Sema &S, TemplateParameterList *TemplateParams,
2411 ArrayRef<TemplateArgument> Params,
2412 ArrayRef<TemplateArgument> Args,
2413 TemplateDeductionInfo &Info,
2414 SmallVectorImpl<DeducedTemplateArgument> &Deduced,
2415 bool NumberOfArgumentsMustMatch) {
2416 // C++0x [temp.deduct.type]p9:
2417 // If the template argument list of P contains a pack expansion that is not
2418 // the last template argument, the entire template argument list is a
2419 // non-deduced context.
2420 if (hasPackExpansionBeforeEnd(Params))
2421 return Sema::TDK_Success;
2423 // C++0x [temp.deduct.type]p9:
2424 // If P has a form that contains <T> or <i>, then each argument Pi of the
2425 // respective template argument list P is compared with the corresponding
2426 // argument Ai of the corresponding template argument list of A.
2427 unsigned ArgIdx = 0, ParamIdx = 0;
2428 for (; hasTemplateArgumentForDeduction(Params, ParamIdx); ++ParamIdx) {
2429 if (!Params[ParamIdx].isPackExpansion()) {
2430 // The simple case: deduce template arguments by matching Pi and Ai.
2432 // Check whether we have enough arguments.
2433 if (!hasTemplateArgumentForDeduction(Args, ArgIdx))
2434 return NumberOfArgumentsMustMatch
2435 ? Sema::TDK_MiscellaneousDeductionFailure
2436 : Sema::TDK_Success;
2438 // C++1z [temp.deduct.type]p9:
2439 // During partial ordering, if Ai was originally a pack expansion [and]
2440 // Pi is not a pack expansion, template argument deduction fails.
2441 if (Args[ArgIdx].isPackExpansion())
2442 return Sema::TDK_MiscellaneousDeductionFailure;
2444 // Perform deduction for this Pi/Ai pair.
2445 if (Sema::TemplateDeductionResult Result
2446 = DeduceTemplateArguments(S, TemplateParams,
2447 Params[ParamIdx], Args[ArgIdx],
2451 // Move to the next argument.
2456 // The parameter is a pack expansion.
2458 // C++0x [temp.deduct.type]p9:
2459 // If Pi is a pack expansion, then the pattern of Pi is compared with
2460 // each remaining argument in the template argument list of A. Each
2461 // comparison deduces template arguments for subsequent positions in the
2462 // template parameter packs expanded by Pi.
2463 TemplateArgument Pattern = Params[ParamIdx].getPackExpansionPattern();
2465 // Prepare to deduce the packs within the pattern.
2466 PackDeductionScope PackScope(S, TemplateParams, Deduced, Info, Pattern);
2468 // Keep track of the deduced template arguments for each parameter pack
2469 // expanded by this pack expansion (the outer index) and for each
2470 // template argument (the inner SmallVectors).
2471 for (; hasTemplateArgumentForDeduction(Args, ArgIdx) &&
2472 PackScope.hasNextElement();
2474 // Deduce template arguments from the pattern.
2475 if (Sema::TemplateDeductionResult Result
2476 = DeduceTemplateArguments(S, TemplateParams, Pattern, Args[ArgIdx],
2480 PackScope.nextPackElement();
2483 // Build argument packs for each of the parameter packs expanded by this
2485 if (auto Result = PackScope.finish())
2489 return Sema::TDK_Success;
2492 static Sema::TemplateDeductionResult
2493 DeduceTemplateArguments(Sema &S,
2494 TemplateParameterList *TemplateParams,
2495 const TemplateArgumentList &ParamList,
2496 const TemplateArgumentList &ArgList,
2497 TemplateDeductionInfo &Info,
2498 SmallVectorImpl<DeducedTemplateArgument> &Deduced) {
2499 return DeduceTemplateArguments(S, TemplateParams, ParamList.asArray(),
2500 ArgList.asArray(), Info, Deduced,
2501 /*NumberOfArgumentsMustMatch*/false);
2504 /// Determine whether two template arguments are the same.
2505 static bool isSameTemplateArg(ASTContext &Context,
2507 const TemplateArgument &Y,
2508 bool PackExpansionMatchesPack = false) {
2509 // If we're checking deduced arguments (X) against original arguments (Y),
2510 // we will have flattened packs to non-expansions in X.
2511 if (PackExpansionMatchesPack && X.isPackExpansion() && !Y.isPackExpansion())
2512 X = X.getPackExpansionPattern();
2514 if (X.getKind() != Y.getKind())
2517 switch (X.getKind()) {
2518 case TemplateArgument::Null:
2519 llvm_unreachable("Comparing NULL template argument");
2521 case TemplateArgument::Type:
2522 return Context.getCanonicalType(X.getAsType()) ==
2523 Context.getCanonicalType(Y.getAsType());
2525 case TemplateArgument::Declaration:
2526 return isSameDeclaration(X.getAsDecl(), Y.getAsDecl());
2528 case TemplateArgument::NullPtr:
2529 return Context.hasSameType(X.getNullPtrType(), Y.getNullPtrType());
2531 case TemplateArgument::Template:
2532 case TemplateArgument::TemplateExpansion:
2533 return Context.getCanonicalTemplateName(
2534 X.getAsTemplateOrTemplatePattern()).getAsVoidPointer() ==
2535 Context.getCanonicalTemplateName(
2536 Y.getAsTemplateOrTemplatePattern()).getAsVoidPointer();
2538 case TemplateArgument::Integral:
2539 return hasSameExtendedValue(X.getAsIntegral(), Y.getAsIntegral());
2541 case TemplateArgument::Expression: {
2542 llvm::FoldingSetNodeID XID, YID;
2543 X.getAsExpr()->Profile(XID, Context, true);
2544 Y.getAsExpr()->Profile(YID, Context, true);
2548 case TemplateArgument::Pack:
2549 if (X.pack_size() != Y.pack_size())
2552 for (TemplateArgument::pack_iterator XP = X.pack_begin(),
2553 XPEnd = X.pack_end(),
2554 YP = Y.pack_begin();
2555 XP != XPEnd; ++XP, ++YP)
2556 if (!isSameTemplateArg(Context, *XP, *YP, PackExpansionMatchesPack))
2562 llvm_unreachable("Invalid TemplateArgument Kind!");
2565 /// Allocate a TemplateArgumentLoc where all locations have
2566 /// been initialized to the given location.
2568 /// \param Arg The template argument we are producing template argument
2569 /// location information for.
2571 /// \param NTTPType For a declaration template argument, the type of
2572 /// the non-type template parameter that corresponds to this template
2573 /// argument. Can be null if no type sugar is available to add to the
2574 /// type from the template argument.
2576 /// \param Loc The source location to use for the resulting template
2579 Sema::getTrivialTemplateArgumentLoc(const TemplateArgument &Arg,
2580 QualType NTTPType, SourceLocation Loc) {
2581 switch (Arg.getKind()) {
2582 case TemplateArgument::Null:
2583 llvm_unreachable("Can't get a NULL template argument here");
2585 case TemplateArgument::Type:
2586 return TemplateArgumentLoc(
2587 Arg, Context.getTrivialTypeSourceInfo(Arg.getAsType(), Loc));
2589 case TemplateArgument::Declaration: {
2590 if (NTTPType.isNull())
2591 NTTPType = Arg.getParamTypeForDecl();
2592 Expr *E = BuildExpressionFromDeclTemplateArgument(Arg, NTTPType, Loc)
2594 return TemplateArgumentLoc(TemplateArgument(E), E);
2597 case TemplateArgument::NullPtr: {
2598 if (NTTPType.isNull())
2599 NTTPType = Arg.getNullPtrType();
2600 Expr *E = BuildExpressionFromDeclTemplateArgument(Arg, NTTPType, Loc)
2602 return TemplateArgumentLoc(TemplateArgument(NTTPType, /*isNullPtr*/true),
2606 case TemplateArgument::Integral: {
2608 BuildExpressionFromIntegralTemplateArgument(Arg, Loc).getAs<Expr>();
2609 return TemplateArgumentLoc(TemplateArgument(E), E);
2612 case TemplateArgument::Template:
2613 case TemplateArgument::TemplateExpansion: {
2614 NestedNameSpecifierLocBuilder Builder;
2615 TemplateName Template = Arg.getAsTemplateOrTemplatePattern();
2616 if (DependentTemplateName *DTN = Template.getAsDependentTemplateName())
2617 Builder.MakeTrivial(Context, DTN->getQualifier(), Loc);
2618 else if (QualifiedTemplateName *QTN =
2619 Template.getAsQualifiedTemplateName())
2620 Builder.MakeTrivial(Context, QTN->getQualifier(), Loc);
2622 if (Arg.getKind() == TemplateArgument::Template)
2623 return TemplateArgumentLoc(Arg, Builder.getWithLocInContext(Context),
2626 return TemplateArgumentLoc(Arg, Builder.getWithLocInContext(Context),
2630 case TemplateArgument::Expression:
2631 return TemplateArgumentLoc(Arg, Arg.getAsExpr());
2633 case TemplateArgument::Pack:
2634 return TemplateArgumentLoc(Arg, TemplateArgumentLocInfo());
2637 llvm_unreachable("Invalid TemplateArgument Kind!");
2641 Sema::getIdentityTemplateArgumentLoc(NamedDecl *TemplateParm,
2642 SourceLocation Location) {
2643 return getTrivialTemplateArgumentLoc(
2644 Context.getInjectedTemplateArg(TemplateParm), QualType(), Location);
2647 /// Convert the given deduced template argument and add it to the set of
2648 /// fully-converted template arguments.
2650 ConvertDeducedTemplateArgument(Sema &S, NamedDecl *Param,
2651 DeducedTemplateArgument Arg,
2652 NamedDecl *Template,
2653 TemplateDeductionInfo &Info,
2655 SmallVectorImpl<TemplateArgument> &Output) {
2656 auto ConvertArg = [&](DeducedTemplateArgument Arg,
2657 unsigned ArgumentPackIndex) {
2658 // Convert the deduced template argument into a template
2659 // argument that we can check, almost as if the user had written
2660 // the template argument explicitly.
2661 TemplateArgumentLoc ArgLoc =
2662 S.getTrivialTemplateArgumentLoc(Arg, QualType(), Info.getLocation());
2664 // Check the template argument, converting it as necessary.
2665 return S.CheckTemplateArgument(
2666 Param, ArgLoc, Template, Template->getLocation(),
2667 Template->getSourceRange().getEnd(), ArgumentPackIndex, Output,
2669 ? (Arg.wasDeducedFromArrayBound() ? Sema::CTAK_DeducedFromArrayBound
2670 : Sema::CTAK_Deduced)
2671 : Sema::CTAK_Specified);
2674 if (Arg.getKind() == TemplateArgument::Pack) {
2675 // This is a template argument pack, so check each of its arguments against
2676 // the template parameter.
2677 SmallVector<TemplateArgument, 2> PackedArgsBuilder;
2678 for (const auto &P : Arg.pack_elements()) {
2679 // When converting the deduced template argument, append it to the
2680 // general output list. We need to do this so that the template argument
2681 // checking logic has all of the prior template arguments available.
2682 DeducedTemplateArgument InnerArg(P);
2683 InnerArg.setDeducedFromArrayBound(Arg.wasDeducedFromArrayBound());
2684 assert(InnerArg.getKind() != TemplateArgument::Pack &&
2685 "deduced nested pack");
2687 // We deduced arguments for some elements of this pack, but not for
2688 // all of them. This happens if we get a conditionally-non-deduced
2689 // context in a pack expansion (such as an overload set in one of the
2691 S.Diag(Param->getLocation(),
2692 diag::err_template_arg_deduced_incomplete_pack)
2696 if (ConvertArg(InnerArg, PackedArgsBuilder.size()))
2699 // Move the converted template argument into our argument pack.
2700 PackedArgsBuilder.push_back(Output.pop_back_val());
2703 // If the pack is empty, we still need to substitute into the parameter
2704 // itself, in case that substitution fails.
2705 if (PackedArgsBuilder.empty()) {
2706 LocalInstantiationScope Scope(S);
2707 TemplateArgumentList TemplateArgs(TemplateArgumentList::OnStack, Output);
2708 MultiLevelTemplateArgumentList Args(TemplateArgs);
2710 if (auto *NTTP = dyn_cast<NonTypeTemplateParmDecl>(Param)) {
2711 Sema::InstantiatingTemplate Inst(S, Template->getLocation(), Template,
2713 Template->getSourceRange());
2714 if (Inst.isInvalid() ||
2715 S.SubstType(NTTP->getType(), Args, NTTP->getLocation(),
2716 NTTP->getDeclName()).isNull())
2718 } else if (auto *TTP = dyn_cast<TemplateTemplateParmDecl>(Param)) {
2719 Sema::InstantiatingTemplate Inst(S, Template->getLocation(), Template,
2721 Template->getSourceRange());
2722 if (Inst.isInvalid() || !S.SubstDecl(TTP, S.CurContext, Args))
2725 // For type parameters, no substitution is ever required.
2728 // Create the resulting argument pack.
2730 TemplateArgument::CreatePackCopy(S.Context, PackedArgsBuilder));
2734 return ConvertArg(Arg, 0);
2737 // FIXME: This should not be a template, but
2738 // ClassTemplatePartialSpecializationDecl sadly does not derive from
2740 template<typename TemplateDeclT>
2741 static Sema::TemplateDeductionResult ConvertDeducedTemplateArguments(
2742 Sema &S, TemplateDeclT *Template, bool IsDeduced,
2743 SmallVectorImpl<DeducedTemplateArgument> &Deduced,
2744 TemplateDeductionInfo &Info, SmallVectorImpl<TemplateArgument> &Builder,
2745 LocalInstantiationScope *CurrentInstantiationScope = nullptr,
2746 unsigned NumAlreadyConverted = 0, bool PartialOverloading = false) {
2747 TemplateParameterList *TemplateParams = Template->getTemplateParameters();
2749 for (unsigned I = 0, N = TemplateParams->size(); I != N; ++I) {
2750 NamedDecl *Param = TemplateParams->getParam(I);
2752 // C++0x [temp.arg.explicit]p3:
2753 // A trailing template parameter pack (14.5.3) not otherwise deduced will
2754 // be deduced to an empty sequence of template arguments.
2755 // FIXME: Where did the word "trailing" come from?
2756 if (Deduced[I].isNull() && Param->isTemplateParameterPack()) {
2758 PackDeductionScope(S, TemplateParams, Deduced, Info, I).finish())
2762 if (!Deduced[I].isNull()) {
2763 if (I < NumAlreadyConverted) {
2764 // We may have had explicitly-specified template arguments for a
2765 // template parameter pack (that may or may not have been extended
2766 // via additional deduced arguments).
2767 if (Param->isParameterPack() && CurrentInstantiationScope &&
2768 CurrentInstantiationScope->getPartiallySubstitutedPack() == Param) {
2769 // Forget the partially-substituted pack; its substitution is now
2771 CurrentInstantiationScope->ResetPartiallySubstitutedPack();
2772 // We still need to check the argument in case it was extended by
2775 // We have already fully type-checked and converted this
2776 // argument, because it was explicitly-specified. Just record the
2777 // presence of this argument.
2778 Builder.push_back(Deduced[I]);
2783 // We may have deduced this argument, so it still needs to be
2784 // checked and converted.
2785 if (ConvertDeducedTemplateArgument(S, Param, Deduced[I], Template, Info,
2786 IsDeduced, Builder)) {
2787 Info.Param = makeTemplateParameter(Param);
2788 // FIXME: These template arguments are temporary. Free them!
2789 Info.reset(TemplateArgumentList::CreateCopy(S.Context, Builder));
2790 return Sema::TDK_SubstitutionFailure;
2796 // Substitute into the default template argument, if available.
2797 bool HasDefaultArg = false;
2798 TemplateDecl *TD = dyn_cast<TemplateDecl>(Template);
2800 assert(isa<ClassTemplatePartialSpecializationDecl>(Template) ||
2801 isa<VarTemplatePartialSpecializationDecl>(Template));
2802 return Sema::TDK_Incomplete;
2805 TemplateArgumentLoc DefArg = S.SubstDefaultTemplateArgumentIfAvailable(
2806 TD, TD->getLocation(), TD->getSourceRange().getEnd(), Param, Builder,
2809 // If there was no default argument, deduction is incomplete.
2810 if (DefArg.getArgument().isNull()) {
2811 Info.Param = makeTemplateParameter(
2812 const_cast<NamedDecl *>(TemplateParams->getParam(I)));
2813 Info.reset(TemplateArgumentList::CreateCopy(S.Context, Builder));
2814 if (PartialOverloading) break;
2816 return HasDefaultArg ? Sema::TDK_SubstitutionFailure
2817 : Sema::TDK_Incomplete;
2820 // Check whether we can actually use the default argument.
2821 if (S.CheckTemplateArgument(Param, DefArg, TD, TD->getLocation(),
2822 TD->getSourceRange().getEnd(), 0, Builder,
2823 Sema::CTAK_Specified)) {
2824 Info.Param = makeTemplateParameter(
2825 const_cast<NamedDecl *>(TemplateParams->getParam(I)));
2826 // FIXME: These template arguments are temporary. Free them!
2827 Info.reset(TemplateArgumentList::CreateCopy(S.Context, Builder));
2828 return Sema::TDK_SubstitutionFailure;
2831 // If we get here, we successfully used the default template argument.
2834 return Sema::TDK_Success;
2837 static DeclContext *getAsDeclContextOrEnclosing(Decl *D) {
2838 if (auto *DC = dyn_cast<DeclContext>(D))
2840 return D->getDeclContext();
2843 template<typename T> struct IsPartialSpecialization {
2844 static constexpr bool value = false;
2847 struct IsPartialSpecialization<ClassTemplatePartialSpecializationDecl> {
2848 static constexpr bool value = true;
2851 struct IsPartialSpecialization<VarTemplatePartialSpecializationDecl> {
2852 static constexpr bool value = true;
2855 template<typename TemplateDeclT>
2856 static Sema::TemplateDeductionResult
2857 CheckDeducedArgumentConstraints(Sema& S, TemplateDeclT *Template,
2858 ArrayRef<TemplateArgument> DeducedArgs,
2859 TemplateDeductionInfo& Info) {
2860 llvm::SmallVector<const Expr *, 3> AssociatedConstraints;
2861 Template->getAssociatedConstraints(AssociatedConstraints);
2862 if (S.CheckConstraintSatisfaction(Template, AssociatedConstraints,
2863 DeducedArgs, Info.getLocation(),
2864 Info.AssociatedConstraintsSatisfaction) ||
2865 !Info.AssociatedConstraintsSatisfaction.IsSatisfied) {
2866 Info.reset(TemplateArgumentList::CreateCopy(S.Context, DeducedArgs));
2867 return Sema::TDK_ConstraintsNotSatisfied;
2869 return Sema::TDK_Success;
2872 /// Complete template argument deduction for a partial specialization.
2873 template <typename T>
2874 static std::enable_if_t<IsPartialSpecialization<T>::value,
2875 Sema::TemplateDeductionResult>
2876 FinishTemplateArgumentDeduction(
2877 Sema &S, T *Partial, bool IsPartialOrdering,
2878 const TemplateArgumentList &TemplateArgs,
2879 SmallVectorImpl<DeducedTemplateArgument> &Deduced,
2880 TemplateDeductionInfo &Info) {
2881 // Unevaluated SFINAE context.
2882 EnterExpressionEvaluationContext Unevaluated(
2883 S, Sema::ExpressionEvaluationContext::Unevaluated);
2884 Sema::SFINAETrap Trap(S);
2886 Sema::ContextRAII SavedContext(S, getAsDeclContextOrEnclosing(Partial));
2888 // C++ [temp.deduct.type]p2:
2889 // [...] or if any template argument remains neither deduced nor
2890 // explicitly specified, template argument deduction fails.
2891 SmallVector<TemplateArgument, 4> Builder;
2892 if (auto Result = ConvertDeducedTemplateArguments(
2893 S, Partial, IsPartialOrdering, Deduced, Info, Builder))
2896 // Form the template argument list from the deduced template arguments.
2897 TemplateArgumentList *DeducedArgumentList
2898 = TemplateArgumentList::CreateCopy(S.Context, Builder);
2900 Info.reset(DeducedArgumentList);
2902 // Substitute the deduced template arguments into the template
2903 // arguments of the class template partial specialization, and
2904 // verify that the instantiated template arguments are both valid
2905 // and are equivalent to the template arguments originally provided
2906 // to the class template.
2907 LocalInstantiationScope InstScope(S);
2908 auto *Template = Partial->getSpecializedTemplate();
2909 const ASTTemplateArgumentListInfo *PartialTemplArgInfo =
2910 Partial->getTemplateArgsAsWritten();
2911 const TemplateArgumentLoc *PartialTemplateArgs =
2912 PartialTemplArgInfo->getTemplateArgs();
2914 TemplateArgumentListInfo InstArgs(PartialTemplArgInfo->LAngleLoc,
2915 PartialTemplArgInfo->RAngleLoc);
2917 if (S.Subst(PartialTemplateArgs, PartialTemplArgInfo->NumTemplateArgs,
2918 InstArgs, MultiLevelTemplateArgumentList(*DeducedArgumentList))) {
2919 unsigned ArgIdx = InstArgs.size(), ParamIdx = ArgIdx;
2920 if (ParamIdx >= Partial->getTemplateParameters()->size())
2921 ParamIdx = Partial->getTemplateParameters()->size() - 1;
2923 Decl *Param = const_cast<NamedDecl *>(
2924 Partial->getTemplateParameters()->getParam(ParamIdx));
2925 Info.Param = makeTemplateParameter(Param);
2926 Info.FirstArg = PartialTemplateArgs[ArgIdx].getArgument();
2927 return Sema::TDK_SubstitutionFailure;
2930 bool ConstraintsNotSatisfied;
2931 SmallVector<TemplateArgument, 4> ConvertedInstArgs;
2932 if (S.CheckTemplateArgumentList(Template, Partial->getLocation(), InstArgs,
2933 false, ConvertedInstArgs,
2934 /*UpdateArgsWithConversions=*/true,
2935 &ConstraintsNotSatisfied))
2936 return ConstraintsNotSatisfied ? Sema::TDK_ConstraintsNotSatisfied :
2937 Sema::TDK_SubstitutionFailure;
2939 TemplateParameterList *TemplateParams = Template->getTemplateParameters();
2940 for (unsigned I = 0, E = TemplateParams->size(); I != E; ++I) {
2941 TemplateArgument InstArg = ConvertedInstArgs.data()[I];
2942 if (!isSameTemplateArg(S.Context, TemplateArgs[I], InstArg)) {
2943 Info.Param = makeTemplateParameter(TemplateParams->getParam(I));
2944 Info.FirstArg = TemplateArgs[I];
2945 Info.SecondArg = InstArg;
2946 return Sema::TDK_NonDeducedMismatch;
2950 if (Trap.hasErrorOccurred())
2951 return Sema::TDK_SubstitutionFailure;
2953 if (auto Result = CheckDeducedArgumentConstraints(S, Partial, Builder, Info))
2956 return Sema::TDK_Success;
2959 /// Complete template argument deduction for a class or variable template,
2960 /// when partial ordering against a partial specialization.
2961 // FIXME: Factor out duplication with partial specialization version above.
2962 static Sema::TemplateDeductionResult FinishTemplateArgumentDeduction(
2963 Sema &S, TemplateDecl *Template, bool PartialOrdering,
2964 const TemplateArgumentList &TemplateArgs,
2965 SmallVectorImpl<DeducedTemplateArgument> &Deduced,
2966 TemplateDeductionInfo &Info) {
2967 // Unevaluated SFINAE context.
2968 EnterExpressionEvaluationContext Unevaluated(
2969 S, Sema::ExpressionEvaluationContext::Unevaluated);
2970 Sema::SFINAETrap Trap(S);
2972 Sema::ContextRAII SavedContext(S, getAsDeclContextOrEnclosing(Template));
2974 // C++ [temp.deduct.type]p2:
2975 // [...] or if any template argument remains neither deduced nor
2976 // explicitly specified, template argument deduction fails.
2977 SmallVector<TemplateArgument, 4> Builder;
2978 if (auto Result = ConvertDeducedTemplateArguments(
2979 S, Template, /*IsDeduced*/PartialOrdering, Deduced, Info, Builder))
2982 // Check that we produced the correct argument list.
2983 TemplateParameterList *TemplateParams = Template->getTemplateParameters();
2984 for (unsigned I = 0, E = TemplateParams->size(); I != E; ++I) {
2985 TemplateArgument InstArg = Builder[I];
2986 if (!isSameTemplateArg(S.Context, TemplateArgs[I], InstArg,
2987 /*PackExpansionMatchesPack*/true)) {
2988 Info.Param = makeTemplateParameter(TemplateParams->getParam(I));
2989 Info.FirstArg = TemplateArgs[I];
2990 Info.SecondArg = InstArg;
2991 return Sema::TDK_NonDeducedMismatch;
2995 if (Trap.hasErrorOccurred())
2996 return Sema::TDK_SubstitutionFailure;
2998 if (auto Result = CheckDeducedArgumentConstraints(S, Template, Builder,
3002 return Sema::TDK_Success;
3005 /// Perform template argument deduction to determine whether
3006 /// the given template arguments match the given class template
3007 /// partial specialization per C++ [temp.class.spec.match].
3008 Sema::TemplateDeductionResult
3009 Sema::DeduceTemplateArguments(ClassTemplatePartialSpecializationDecl *Partial,
3010 const TemplateArgumentList &TemplateArgs,
3011 TemplateDeductionInfo &Info) {
3012 if (Partial->isInvalidDecl())
3015 // C++ [temp.class.spec.match]p2:
3016 // A partial specialization matches a given actual template
3017 // argument list if the template arguments of the partial
3018 // specialization can be deduced from the actual template argument
3021 // Unevaluated SFINAE context.
3022 EnterExpressionEvaluationContext Unevaluated(
3023 *this, Sema::ExpressionEvaluationContext::Unevaluated);
3024 SFINAETrap Trap(*this);
3026 SmallVector<DeducedTemplateArgument, 4> Deduced;
3027 Deduced.resize(Partial->getTemplateParameters()->size());
3028 if (TemplateDeductionResult Result
3029 = ::DeduceTemplateArguments(*this,
3030 Partial->getTemplateParameters(),
3031 Partial->getTemplateArgs(),
3032 TemplateArgs, Info, Deduced))
3035 SmallVector<TemplateArgument, 4> DeducedArgs(Deduced.begin(), Deduced.end());
3036 InstantiatingTemplate Inst(*this, Info.getLocation(), Partial, DeducedArgs,
3038 if (Inst.isInvalid())
3039 return TDK_InstantiationDepth;
3041 if (Trap.hasErrorOccurred())
3042 return Sema::TDK_SubstitutionFailure;
3044 TemplateDeductionResult Result;
3045 runWithSufficientStackSpace(Info.getLocation(), [&] {
3046 Result = ::FinishTemplateArgumentDeduction(*this, Partial,
3047 /*IsPartialOrdering=*/false,
3048 TemplateArgs, Deduced, Info);
3053 /// Perform template argument deduction to determine whether
3054 /// the given template arguments match the given variable template
3055 /// partial specialization per C++ [temp.class.spec.match].
3056 Sema::TemplateDeductionResult
3057 Sema::DeduceTemplateArguments(VarTemplatePartialSpecializationDecl *Partial,
3058 const TemplateArgumentList &TemplateArgs,
3059 TemplateDeductionInfo &Info) {
3060 if (Partial->isInvalidDecl())
3063 // C++ [temp.class.spec.match]p2:
3064 // A partial specialization matches a given actual template
3065 // argument list if the template arguments of the partial
3066 // specialization can be deduced from the actual template argument
3069 // Unevaluated SFINAE context.
3070 EnterExpressionEvaluationContext Unevaluated(
3071 *this, Sema::ExpressionEvaluationContext::Unevaluated);
3072 SFINAETrap Trap(*this);
3074 SmallVector<DeducedTemplateArgument, 4> Deduced;
3075 Deduced.resize(Partial->getTemplateParameters()->size());
3076 if (TemplateDeductionResult Result = ::DeduceTemplateArguments(
3077 *this, Partial->getTemplateParameters(), Partial->getTemplateArgs(),
3078 TemplateArgs, Info, Deduced))
3081 SmallVector<TemplateArgument, 4> DeducedArgs(Deduced.begin(), Deduced.end());
3082 InstantiatingTemplate Inst(*this, Info.getLocation(), Partial, DeducedArgs,
3084 if (Inst.isInvalid())
3085 return TDK_InstantiationDepth;
3087 if (Trap.hasErrorOccurred())
3088 return Sema::TDK_SubstitutionFailure;
3090 TemplateDeductionResult Result;
3091 runWithSufficientStackSpace(Info.getLocation(), [&] {
3092 Result = ::FinishTemplateArgumentDeduction(*this, Partial,
3093 /*IsPartialOrdering=*/false,
3094 TemplateArgs, Deduced, Info);
3099 /// Determine whether the given type T is a simple-template-id type.
3100 static bool isSimpleTemplateIdType(QualType T) {
3101 if (const TemplateSpecializationType *Spec
3102 = T->getAs<TemplateSpecializationType>())
3103 return Spec->getTemplateName().getAsTemplateDecl() != nullptr;
3105 // C++17 [temp.local]p2:
3106 // the injected-class-name [...] is equivalent to the template-name followed
3107 // by the template-arguments of the class template specialization or partial
3108 // specialization enclosed in <>
3109 // ... which means it's equivalent to a simple-template-id.
3111 // This only arises during class template argument deduction for a copy
3112 // deduction candidate, where it permits slicing.
3113 if (T->getAs<InjectedClassNameType>())
3119 /// Substitute the explicitly-provided template arguments into the
3120 /// given function template according to C++ [temp.arg.explicit].
3122 /// \param FunctionTemplate the function template into which the explicit
3123 /// template arguments will be substituted.
3125 /// \param ExplicitTemplateArgs the explicitly-specified template
3128 /// \param Deduced the deduced template arguments, which will be populated
3129 /// with the converted and checked explicit template arguments.
3131 /// \param ParamTypes will be populated with the instantiated function
3134 /// \param FunctionType if non-NULL, the result type of the function template
3135 /// will also be instantiated and the pointed-to value will be updated with
3136 /// the instantiated function type.
3138 /// \param Info if substitution fails for any reason, this object will be
3139 /// populated with more information about the failure.
3141 /// \returns TDK_Success if substitution was successful, or some failure
3143 Sema::TemplateDeductionResult
3144 Sema::SubstituteExplicitTemplateArguments(
3145 FunctionTemplateDecl *FunctionTemplate,
3146 TemplateArgumentListInfo &ExplicitTemplateArgs,
3147 SmallVectorImpl<DeducedTemplateArgument> &Deduced,
3148 SmallVectorImpl<QualType> &ParamTypes,
3149 QualType *FunctionType,
3150 TemplateDeductionInfo &Info) {
3151 FunctionDecl *Function = FunctionTemplate->getTemplatedDecl();
3152 TemplateParameterList *TemplateParams
3153 = FunctionTemplate->getTemplateParameters();
3155 if (ExplicitTemplateArgs.size() == 0) {
3156 // No arguments to substitute; just copy over the parameter types and
3157 // fill in the function type.
3158 for (auto P : Function->parameters())
3159 ParamTypes.push_back(P->getType());
3162 *FunctionType = Function->getType();
3166 // Unevaluated SFINAE context.
3167 EnterExpressionEvaluationContext Unevaluated(
3168 *this, Sema::ExpressionEvaluationContext::Unevaluated);
3169 SFINAETrap Trap(*this);
3171 // C++ [temp.arg.explicit]p3:
3172 // Template arguments that are present shall be specified in the
3173 // declaration order of their corresponding template-parameters. The
3174 // template argument list shall not specify more template-arguments than
3175 // there are corresponding template-parameters.
3176 SmallVector<TemplateArgument, 4> Builder;
3178 // Enter a new template instantiation context where we check the
3179 // explicitly-specified template arguments against this function template,
3180 // and then substitute them into the function parameter types.
3181 SmallVector<TemplateArgument, 4> DeducedArgs;
3182 InstantiatingTemplate Inst(
3183 *this, Info.getLocation(), FunctionTemplate, DeducedArgs,
3184 CodeSynthesisContext::ExplicitTemplateArgumentSubstitution, Info);
3185 if (Inst.isInvalid())
3186 return TDK_InstantiationDepth;
3188 if (CheckTemplateArgumentList(FunctionTemplate, SourceLocation(),
3189 ExplicitTemplateArgs, true, Builder, false) ||
3190 Trap.hasErrorOccurred()) {
3191 unsigned Index = Builder.size();
3192 if (Index >= TemplateParams->size())
3193 return TDK_SubstitutionFailure;
3194 Info.Param = makeTemplateParameter(TemplateParams->getParam(Index));
3195 return TDK_InvalidExplicitArguments;
3198 // Form the template argument list from the explicitly-specified
3199 // template arguments.
3200 TemplateArgumentList *ExplicitArgumentList
3201 = TemplateArgumentList::CreateCopy(Context, Builder);
3202 Info.setExplicitArgs(ExplicitArgumentList);
3204 // Template argument deduction and the final substitution should be
3205 // done in the context of the templated declaration. Explicit
3206 // argument substitution, on the other hand, needs to happen in the
3208 ContextRAII SavedContext(*this, FunctionTemplate->getTemplatedDecl());
3210 // If we deduced template arguments for a template parameter pack,
3211 // note that the template argument pack is partially substituted and record
3212 // the explicit template arguments. They'll be used as part of deduction
3213 // for this template parameter pack.
3214 unsigned PartiallySubstitutedPackIndex = -1u;
3215 if (!Builder.empty()) {
3216 const TemplateArgument &Arg = Builder.back();
3217 if (Arg.getKind() == TemplateArgument::Pack) {
3218 auto *Param = TemplateParams->getParam(Builder.size() - 1);
3219 // If this is a fully-saturated fixed-size pack, it should be
3220 // fully-substituted, not partially-substituted.
3221 Optional<unsigned> Expansions = getExpandedPackSize(Param);
3222 if (!Expansions || Arg.pack_size() < *Expansions) {
3223 PartiallySubstitutedPackIndex = Builder.size() - 1;
3224 CurrentInstantiationScope->SetPartiallySubstitutedPack(
3225 Param, Arg.pack_begin(), Arg.pack_size());
3230 const FunctionProtoType *Proto
3231 = Function->getType()->getAs<FunctionProtoType>();
3232 assert(Proto && "Function template does not have a prototype?");
3234 // Isolate our substituted parameters from our caller.
3235 LocalInstantiationScope InstScope(*this, /*MergeWithOuterScope*/true);
3237 ExtParameterInfoBuilder ExtParamInfos;
3239 // Instantiate the types of each of the function parameters given the
3240 // explicitly-specified template arguments. If the function has a trailing
3241 // return type, substitute it after the arguments to ensure we substitute
3242 // in lexical order.
3243 if (Proto->hasTrailingReturn()) {
3244 if (SubstParmTypes(Function->getLocation(), Function->parameters(),
3245 Proto->getExtParameterInfosOrNull(),
3246 MultiLevelTemplateArgumentList(*ExplicitArgumentList),
3247 ParamTypes, /*params*/ nullptr, ExtParamInfos))
3248 return TDK_SubstitutionFailure;
3251 // Instantiate the return type.
3252 QualType ResultType;
3254 // C++11 [expr.prim.general]p3:
3255 // If a declaration declares a member function or member function
3256 // template of a class X, the expression this is a prvalue of type
3257 // "pointer to cv-qualifier-seq X" between the optional cv-qualifer-seq
3258 // and the end of the function-definition, member-declarator, or
3260 Qualifiers ThisTypeQuals;
3261 CXXRecordDecl *ThisContext = nullptr;
3262 if (CXXMethodDecl *Method = dyn_cast<CXXMethodDecl>(Function)) {
3263 ThisContext = Method->getParent();
3264 ThisTypeQuals = Method->getMethodQualifiers();
3267 CXXThisScopeRAII ThisScope(*this, ThisContext, ThisTypeQuals,
3268 getLangOpts().CPlusPlus11);
3271 SubstType(Proto->getReturnType(),
3272 MultiLevelTemplateArgumentList(*ExplicitArgumentList),
3273 Function->getTypeSpecStartLoc(), Function->getDeclName());
3274 if (ResultType.isNull() || Trap.hasErrorOccurred())
3275 return TDK_SubstitutionFailure;
3276 // CUDA: Kernel function must have 'void' return type.
3277 if (getLangOpts().CUDA)
3278 if (Function->hasAttr<CUDAGlobalAttr>() && !ResultType->isVoidType()) {
3279 Diag(Function->getLocation(), diag::err_kern_type_not_void_return)
3280 << Function->getType() << Function->getSourceRange();
3281 return TDK_SubstitutionFailure;
3285 // Instantiate the types of each of the function parameters given the
3286 // explicitly-specified template arguments if we didn't do so earlier.
3287 if (!Proto->hasTrailingReturn() &&
3288 SubstParmTypes(Function->getLocation(), Function->parameters(),
3289 Proto->getExtParameterInfosOrNull(),
3290 MultiLevelTemplateArgumentList(*ExplicitArgumentList),
3291 ParamTypes, /*params*/ nullptr, ExtParamInfos))
3292 return TDK_SubstitutionFailure;
3295 auto EPI = Proto->getExtProtoInfo();
3296 EPI.ExtParameterInfos = ExtParamInfos.getPointerOrNull(ParamTypes.size());
3298 // In C++1z onwards, exception specifications are part of the function type,
3299 // so substitution into the type must also substitute into the exception
3301 SmallVector<QualType, 4> ExceptionStorage;
3302 if (getLangOpts().CPlusPlus17 &&
3304 Function->getLocation(), EPI.ExceptionSpec, ExceptionStorage,
3305 MultiLevelTemplateArgumentList(*ExplicitArgumentList)))
3306 return TDK_SubstitutionFailure;
3308 *FunctionType = BuildFunctionType(ResultType, ParamTypes,
3309 Function->getLocation(),
3310 Function->getDeclName(),
3312 if (FunctionType->isNull() || Trap.hasErrorOccurred())
3313 return TDK_SubstitutionFailure;
3316 // C++ [temp.arg.explicit]p2:
3317 // Trailing template arguments that can be deduced (14.8.2) may be
3318 // omitted from the list of explicit template-arguments. If all of the
3319 // template arguments can be deduced, they may all be omitted; in this
3320 // case, the empty template argument list <> itself may also be omitted.
3322 // Take all of the explicitly-specified arguments and put them into
3323 // the set of deduced template arguments. The partially-substituted
3324 // parameter pack, however, will be set to NULL since the deduction
3325 // mechanism handles the partially-substituted argument pack directly.
3326 Deduced.reserve(TemplateParams->size());
3327 for (unsigned I = 0, N = ExplicitArgumentList->size(); I != N; ++I) {
3328 const TemplateArgument &Arg = ExplicitArgumentList->get(I);
3329 if (I == PartiallySubstitutedPackIndex)
3330 Deduced.push_back(DeducedTemplateArgument());
3332 Deduced.push_back(Arg);
3338 /// Check whether the deduced argument type for a call to a function
3339 /// template matches the actual argument type per C++ [temp.deduct.call]p4.
3340 static Sema::TemplateDeductionResult
3341 CheckOriginalCallArgDeduction(Sema &S, TemplateDeductionInfo &Info,
3342 Sema::OriginalCallArg OriginalArg,
3343 QualType DeducedA) {
3344 ASTContext &Context = S.Context;
3346 auto Failed = [&]() -> Sema::TemplateDeductionResult {
3347 Info.FirstArg = TemplateArgument(DeducedA);
3348 Info.SecondArg = TemplateArgument(OriginalArg.OriginalArgType);
3349 Info.CallArgIndex = OriginalArg.ArgIdx;
3350 return OriginalArg.DecomposedParam ? Sema::TDK_DeducedMismatchNested
3351 : Sema::TDK_DeducedMismatch;
3354 QualType A = OriginalArg.OriginalArgType;
3355 QualType OriginalParamType = OriginalArg.OriginalParamType;
3357 // Check for type equality (top-level cv-qualifiers are ignored).
3358 if (Context.hasSameUnqualifiedType(A, DeducedA))
3359 return Sema::TDK_Success;
3361 // Strip off references on the argument types; they aren't needed for
3362 // the following checks.
3363 if (const ReferenceType *DeducedARef = DeducedA->getAs<ReferenceType>())
3364 DeducedA = DeducedARef->getPointeeType();
3365 if (const ReferenceType *ARef = A->getAs<ReferenceType>())
3366 A = ARef->getPointeeType();
3368 // C++ [temp.deduct.call]p4:
3369 // [...] However, there are three cases that allow a difference:
3370 // - If the original P is a reference type, the deduced A (i.e., the
3371 // type referred to by the reference) can be more cv-qualified than
3372 // the transformed A.
3373 if (const ReferenceType *OriginalParamRef
3374 = OriginalParamType->getAs<ReferenceType>()) {
3375 // We don't want to keep the reference around any more.
3376 OriginalParamType = OriginalParamRef->getPointeeType();
3378 // FIXME: Resolve core issue (no number yet): if the original P is a
3379 // reference type and the transformed A is function type "noexcept F",
3380 // the deduced A can be F.
3382 if (A->isFunctionType() && S.IsFunctionConversion(A, DeducedA, Tmp))
3383 return Sema::TDK_Success;
3385 Qualifiers AQuals = A.getQualifiers();
3386 Qualifiers DeducedAQuals = DeducedA.getQualifiers();
3388 // Under Objective-C++ ARC, the deduced type may have implicitly
3389 // been given strong or (when dealing with a const reference)
3390 // unsafe_unretained lifetime. If so, update the original
3391 // qualifiers to include this lifetime.
3392 if (S.getLangOpts().ObjCAutoRefCount &&
3393 ((DeducedAQuals.getObjCLifetime() == Qualifiers::OCL_Strong &&
3394 AQuals.getObjCLifetime() == Qualifiers::OCL_None) ||
3395 (DeducedAQuals.hasConst() &&
3396 DeducedAQuals.getObjCLifetime() == Qualifiers::OCL_ExplicitNone))) {
3397 AQuals.setObjCLifetime(DeducedAQuals.getObjCLifetime());
3400 if (AQuals == DeducedAQuals) {
3401 // Qualifiers match; there's nothing to do.
3402 } else if (!DeducedAQuals.compatiblyIncludes(AQuals)) {
3405 // Qualifiers are compatible, so have the argument type adopt the
3406 // deduced argument type's qualifiers as if we had performed the
3407 // qualification conversion.
3408 A = Context.getQualifiedType(A.getUnqualifiedType(), DeducedAQuals);
3412 // - The transformed A can be another pointer or pointer to member
3413 // type that can be converted to the deduced A via a function pointer
3414 // conversion and/or a qualification conversion.
3416 // Also allow conversions which merely strip __attribute__((noreturn)) from
3417 // function types (recursively).
3418 bool ObjCLifetimeConversion = false;
3420 if ((A->isAnyPointerType() || A->isMemberPointerType()) &&
3421 (S.IsQualificationConversion(A, DeducedA, false,
3422 ObjCLifetimeConversion) ||
3423 S.IsFunctionConversion(A, DeducedA, ResultTy)))
3424 return Sema::TDK_Success;
3426 // - If P is a class and P has the form simple-template-id, then the
3427 // transformed A can be a derived class of the deduced A. [...]
3428 // [...] Likewise, if P is a pointer to a class of the form
3429 // simple-template-id, the transformed A can be a pointer to a
3430 // derived class pointed to by the deduced A.
3431 if (const PointerType *OriginalParamPtr
3432 = OriginalParamType->getAs<PointerType>()) {
3433 if (const PointerType *DeducedAPtr = DeducedA->getAs<PointerType>()) {
3434 if (const PointerType *APtr = A->getAs<PointerType>()) {
3435 if (A->getPointeeType()->isRecordType()) {
3436 OriginalParamType = OriginalParamPtr->getPointeeType();
3437 DeducedA = DeducedAPtr->getPointeeType();
3438 A = APtr->getPointeeType();
3444 if (Context.hasSameUnqualifiedType(A, DeducedA))
3445 return Sema::TDK_Success;
3447 if (A->isRecordType() && isSimpleTemplateIdType(OriginalParamType) &&
3448 S.IsDerivedFrom(Info.getLocation(), A, DeducedA))
3449 return Sema::TDK_Success;
3454 /// Find the pack index for a particular parameter index in an instantiation of
3455 /// a function template with specific arguments.
3457 /// \return The pack index for whichever pack produced this parameter, or -1
3458 /// if this was not produced by a parameter. Intended to be used as the
3459 /// ArgumentPackSubstitutionIndex for further substitutions.
3460 // FIXME: We should track this in OriginalCallArgs so we don't need to
3461 // reconstruct it here.
3462 static unsigned getPackIndexForParam(Sema &S,
3463 FunctionTemplateDecl *FunctionTemplate,
3464 const MultiLevelTemplateArgumentList &Args,
3465 unsigned ParamIdx) {
3467 for (auto *PD : FunctionTemplate->getTemplatedDecl()->parameters()) {
3468 if (PD->isParameterPack()) {
3469 unsigned NumExpansions =
3470 S.getNumArgumentsInExpansion(PD->getType(), Args).getValueOr(1);
3471 if (Idx + NumExpansions > ParamIdx)
3472 return ParamIdx - Idx;
3473 Idx += NumExpansions;
3475 if (Idx == ParamIdx)
3476 return -1; // Not a pack expansion
3481 llvm_unreachable("parameter index would not be produced from template");
3484 /// Finish template argument deduction for a function template,
3485 /// checking the deduced template arguments for completeness and forming
3486 /// the function template specialization.
3488 /// \param OriginalCallArgs If non-NULL, the original call arguments against
3489 /// which the deduced argument types should be compared.
3490 Sema::TemplateDeductionResult Sema::FinishTemplateArgumentDeduction(
3491 FunctionTemplateDecl *FunctionTemplate,
3492 SmallVectorImpl<DeducedTemplateArgument> &Deduced,
3493 unsigned NumExplicitlySpecified, FunctionDecl *&Specialization,
3494 TemplateDeductionInfo &Info,
3495 SmallVectorImpl<OriginalCallArg> const *OriginalCallArgs,
3496 bool PartialOverloading, llvm::function_ref<bool()> CheckNonDependent) {
3497 // Unevaluated SFINAE context.
3498 EnterExpressionEvaluationContext Unevaluated(
3499 *this, Sema::ExpressionEvaluationContext::Unevaluated);
3500 SFINAETrap Trap(*this);
3502 // Enter a new template instantiation context while we instantiate the
3503 // actual function declaration.
3504 SmallVector<TemplateArgument, 4> DeducedArgs(Deduced.begin(), Deduced.end());
3505 InstantiatingTemplate Inst(
3506 *this, Info.getLocation(), FunctionTemplate, DeducedArgs,
3507 CodeSynthesisContext::DeducedTemplateArgumentSubstitution, Info);
3508 if (Inst.isInvalid())
3509 return TDK_InstantiationDepth;
3511 ContextRAII SavedContext(*this, FunctionTemplate->getTemplatedDecl());
3513 // C++ [temp.deduct.type]p2:
3514 // [...] or if any template argument remains neither deduced nor
3515 // explicitly specified, template argument deduction fails.
3516 SmallVector<TemplateArgument, 4> Builder;
3517 if (auto Result = ConvertDeducedTemplateArguments(
3518 *this, FunctionTemplate, /*IsDeduced*/true, Deduced, Info, Builder,
3519 CurrentInstantiationScope, NumExplicitlySpecified,
3520 PartialOverloading))
3523 // C++ [temp.deduct.call]p10: [DR1391]
3524 // If deduction succeeds for all parameters that contain
3525 // template-parameters that participate in template argument deduction,
3526 // and all template arguments are explicitly specified, deduced, or
3527 // obtained from default template arguments, remaining parameters are then
3528 // compared with the corresponding arguments. For each remaining parameter
3529 // P with a type that was non-dependent before substitution of any
3530 // explicitly-specified template arguments, if the corresponding argument
3531 // A cannot be implicitly converted to P, deduction fails.
3532 if (CheckNonDependent())
3533 return TDK_NonDependentConversionFailure;
3535 // Form the template argument list from the deduced template arguments.
3536 TemplateArgumentList *DeducedArgumentList
3537 = TemplateArgumentList::CreateCopy(Context, Builder);
3538 Info.reset(DeducedArgumentList);
3540 // Substitute the deduced template arguments into the function template
3541 // declaration to produce the function template specialization.
3542 DeclContext *Owner = FunctionTemplate->getDeclContext();
3543 if (FunctionTemplate->getFriendObjectKind())
3544 Owner = FunctionTemplate->getLexicalDeclContext();
3545 MultiLevelTemplateArgumentList SubstArgs(*DeducedArgumentList);
3546 Specialization = cast_or_null<FunctionDecl>(
3547 SubstDecl(FunctionTemplate->getTemplatedDecl(), Owner, SubstArgs));
3548 if (!Specialization || Specialization->isInvalidDecl())
3549 return TDK_SubstitutionFailure;
3551 assert(Specialization->getPrimaryTemplate()->getCanonicalDecl() ==
3552 FunctionTemplate->getCanonicalDecl());
3554 // If the template argument list is owned by the function template
3555 // specialization, release it.
3556 if (Specialization->getTemplateSpecializationArgs() == DeducedArgumentList &&
3557 !Trap.hasErrorOccurred())
3560 // There may have been an error that did not prevent us from constructing a
3561 // declaration. Mark the declaration invalid and return with a substitution
3563 if (Trap.hasErrorOccurred()) {
3564 Specialization->setInvalidDecl(true);
3565 return TDK_SubstitutionFailure;
3568 // C++2a [temp.deduct]p5
3569 // [...] When all template arguments have been deduced [...] all uses of
3570 // template parameters [...] are replaced with the corresponding deduced
3571 // or default argument values.
3572 // [...] If the function template has associated constraints
3573 // ([temp.constr.decl]), those constraints are checked for satisfaction
3574 // ([temp.constr.constr]). If the constraints are not satisfied, type
3576 if (!PartialOverloading ||
3577 (Builder.size() == FunctionTemplate->getTemplateParameters()->size())) {
3578 if (CheckInstantiatedFunctionTemplateConstraints(Info.getLocation(),
3579 Specialization, Builder, Info.AssociatedConstraintsSatisfaction))
3580 return TDK_MiscellaneousDeductionFailure;
3582 if (!Info.AssociatedConstraintsSatisfaction.IsSatisfied) {
3583 Info.reset(TemplateArgumentList::CreateCopy(Context, Builder));
3584 return TDK_ConstraintsNotSatisfied;
3588 if (OriginalCallArgs) {
3589 // C++ [temp.deduct.call]p4:
3590 // In general, the deduction process attempts to find template argument
3591 // values that will make the deduced A identical to A (after the type A
3592 // is transformed as described above). [...]
3593 llvm::SmallDenseMap<std::pair<unsigned, QualType>, QualType> DeducedATypes;
3594 for (unsigned I = 0, N = OriginalCallArgs->size(); I != N; ++I) {
3595 OriginalCallArg OriginalArg = (*OriginalCallArgs)[I];
3597 auto ParamIdx = OriginalArg.ArgIdx;
3598 if (ParamIdx >= Specialization->getNumParams())
3599 // FIXME: This presumably means a pack ended up smaller than we
3600 // expected while deducing. Should this not result in deduction
3601 // failure? Can it even happen?
3605 if (!OriginalArg.DecomposedParam) {
3606 // P is one of the function parameters, just look up its substituted
3608 DeducedA = Specialization->getParamDecl(ParamIdx)->getType();
3610 // P is a decomposed element of a parameter corresponding to a
3611 // braced-init-list argument. Substitute back into P to find the
3613 QualType &CacheEntry =
3614 DeducedATypes[{ParamIdx, OriginalArg.OriginalParamType}];
3615 if (CacheEntry.isNull()) {
3616 ArgumentPackSubstitutionIndexRAII PackIndex(
3617 *this, getPackIndexForParam(*this, FunctionTemplate, SubstArgs,
3620 SubstType(OriginalArg.OriginalParamType, SubstArgs,
3621 Specialization->getTypeSpecStartLoc(),
3622 Specialization->getDeclName());
3624 DeducedA = CacheEntry;
3628 CheckOriginalCallArgDeduction(*this, Info, OriginalArg, DeducedA))
3633 // If we suppressed any diagnostics while performing template argument
3634 // deduction, and if we haven't already instantiated this declaration,
3635 // keep track of these diagnostics. They'll be emitted if this specialization
3636 // is actually used.
3637 if (Info.diag_begin() != Info.diag_end()) {
3638 SuppressedDiagnosticsMap::iterator
3639 Pos = SuppressedDiagnostics.find(Specialization->getCanonicalDecl());
3640 if (Pos == SuppressedDiagnostics.end())
3641 SuppressedDiagnostics[Specialization->getCanonicalDecl()]
3642 .append(Info.diag_begin(), Info.diag_end());
3648 /// Gets the type of a function for template-argument-deducton
3649 /// purposes when it's considered as part of an overload set.
3650 static QualType GetTypeOfFunction(Sema &S, const OverloadExpr::FindResult &R,
3652 // We may need to deduce the return type of the function now.
3653 if (S.getLangOpts().CPlusPlus14 && Fn->getReturnType()->isUndeducedType() &&
3654 S.DeduceReturnType(Fn, R.Expression->getExprLoc(), /*Diagnose*/ false))
3657 if (CXXMethodDecl *Method = dyn_cast<CXXMethodDecl>(Fn))
3658 if (Method->isInstance()) {
3659 // An instance method that's referenced in a form that doesn't
3660 // look like a member pointer is just invalid.
3661 if (!R.HasFormOfMemberPointer)
3664 return S.Context.getMemberPointerType(Fn->getType(),
3665 S.Context.getTypeDeclType(Method->getParent()).getTypePtr());
3668 if (!R.IsAddressOfOperand) return Fn->getType();
3669 return S.Context.getPointerType(Fn->getType());
3672 /// Apply the deduction rules for overload sets.
3674 /// \return the null type if this argument should be treated as an
3675 /// undeduced context
3677 ResolveOverloadForDeduction(Sema &S, TemplateParameterList *TemplateParams,
3678 Expr *Arg, QualType ParamType,
3679 bool ParamWasReference) {
3681 OverloadExpr::FindResult R = OverloadExpr::find(Arg);
3683 OverloadExpr *Ovl = R.Expression;
3685 // C++0x [temp.deduct.call]p4
3687 if (ParamWasReference)
3688 TDF |= TDF_ParamWithReferenceType;
3689 if (R.IsAddressOfOperand)
3690 TDF |= TDF_IgnoreQualifiers;
3692 // C++0x [temp.deduct.call]p6:
3693 // When P is a function type, pointer to function type, or pointer
3694 // to member function type:
3696 if (!ParamType->isFunctionType() &&
3697 !ParamType->isFunctionPointerType() &&
3698 !ParamType->isMemberFunctionPointerType()) {
3699 if (Ovl->hasExplicitTemplateArgs()) {
3700 // But we can still look for an explicit specialization.
3701 if (FunctionDecl *ExplicitSpec
3702 = S.ResolveSingleFunctionTemplateSpecialization(Ovl))
3703 return GetTypeOfFunction(S, R, ExplicitSpec);
3707 if (FunctionDecl *Viable =
3708 S.resolveAddressOfSingleOverloadCandidate(Arg, DAP))
3709 return GetTypeOfFunction(S, R, Viable);
3714 // Gather the explicit template arguments, if any.
3715 TemplateArgumentListInfo ExplicitTemplateArgs;
3716 if (Ovl->hasExplicitTemplateArgs())
3717 Ovl->copyTemplateArgumentsInto(ExplicitTemplateArgs);
3719 for (UnresolvedSetIterator I = Ovl->decls_begin(),
3720 E = Ovl->decls_end(); I != E; ++I) {
3721 NamedDecl *D = (*I)->getUnderlyingDecl();
3723 if (FunctionTemplateDecl *FunTmpl = dyn_cast<FunctionTemplateDecl>(D)) {
3724 // - If the argument is an overload set containing one or more
3725 // function templates, the parameter is treated as a
3726 // non-deduced context.
3727 if (!Ovl->hasExplicitTemplateArgs())
3730 // Otherwise, see if we can resolve a function type
3731 FunctionDecl *Specialization = nullptr;
3732 TemplateDeductionInfo Info(Ovl->getNameLoc());
3733 if (S.DeduceTemplateArguments(FunTmpl, &ExplicitTemplateArgs,
3734 Specialization, Info))
3740 FunctionDecl *Fn = cast<FunctionDecl>(D);
3741 QualType ArgType = GetTypeOfFunction(S, R, Fn);
3742 if (ArgType.isNull()) continue;
3744 // Function-to-pointer conversion.
3745 if (!ParamWasReference && ParamType->isPointerType() &&
3746 ArgType->isFunctionType())
3747 ArgType = S.Context.getPointerType(ArgType);
3749 // - If the argument is an overload set (not containing function
3750 // templates), trial argument deduction is attempted using each
3751 // of the members of the set. If deduction succeeds for only one
3752 // of the overload set members, that member is used as the
3753 // argument value for the deduction. If deduction succeeds for
3754 // more than one member of the overload set the parameter is
3755 // treated as a non-deduced context.
3757 // We do all of this in a fresh context per C++0x [temp.deduct.type]p2:
3758 // Type deduction is done independently for each P/A pair, and
3759 // the deduced template argument values are then combined.
3760 // So we do not reject deductions which were made elsewhere.
3761 SmallVector<DeducedTemplateArgument, 8>
3762 Deduced(TemplateParams->size());
3763 TemplateDeductionInfo Info(Ovl->getNameLoc());
3764 Sema::TemplateDeductionResult Result
3765 = DeduceTemplateArgumentsByTypeMatch(S, TemplateParams, ParamType,
3766 ArgType, Info, Deduced, TDF);
3767 if (Result) continue;
3768 if (!Match.isNull())
3776 /// Perform the adjustments to the parameter and argument types
3777 /// described in C++ [temp.deduct.call].
3779 /// \returns true if the caller should not attempt to perform any template
3780 /// argument deduction based on this P/A pair because the argument is an
3781 /// overloaded function set that could not be resolved.
3782 static bool AdjustFunctionParmAndArgTypesForDeduction(
3783 Sema &S, TemplateParameterList *TemplateParams, unsigned FirstInnerIndex,
3784 QualType &ParamType, QualType &ArgType, Expr *Arg, unsigned &TDF) {
3785 // C++0x [temp.deduct.call]p3:
3786 // If P is a cv-qualified type, the top level cv-qualifiers of P's type
3787 // are ignored for type deduction.
3788 if (ParamType.hasQualifiers())
3789 ParamType = ParamType.getUnqualifiedType();
3791 // [...] If P is a reference type, the type referred to by P is
3792 // used for type deduction.
3793 const ReferenceType *ParamRefType = ParamType->getAs<ReferenceType>();
3795 ParamType = ParamRefType->getPointeeType();
3797 // Overload sets usually make this parameter an undeduced context,
3798 // but there are sometimes special circumstances. Typically
3799 // involving a template-id-expr.
3800 if (ArgType == S.Context.OverloadTy) {
3801 ArgType = ResolveOverloadForDeduction(S, TemplateParams,
3803 ParamRefType != nullptr);
3804 if (ArgType.isNull())
3809 // If the argument has incomplete array type, try to complete its type.
3810 if (ArgType->isIncompleteArrayType()) {
3811 S.completeExprArrayBound(Arg);
3812 ArgType = Arg->getType();
3815 // C++1z [temp.deduct.call]p3:
3816 // If P is a forwarding reference and the argument is an lvalue, the type
3817 // "lvalue reference to A" is used in place of A for type deduction.
3818 if (isForwardingReference(QualType(ParamRefType, 0), FirstInnerIndex) &&
3820 ArgType = S.Context.getLValueReferenceType(ArgType);
3822 // C++ [temp.deduct.call]p2:
3823 // If P is not a reference type:
3824 // - If A is an array type, the pointer type produced by the
3825 // array-to-pointer standard conversion (4.2) is used in place of
3826 // A for type deduction; otherwise,
3827 if (ArgType->isArrayType())
3828 ArgType = S.Context.getArrayDecayedType(ArgType);
3829 // - If A is a function type, the pointer type produced by the
3830 // function-to-pointer standard conversion (4.3) is used in place
3831 // of A for type deduction; otherwise,
3832 else if (ArgType->isFunctionType())
3833 ArgType = S.Context.getPointerType(ArgType);
3835 // - If A is a cv-qualified type, the top level cv-qualifiers of A's
3836 // type are ignored for type deduction.
3837 ArgType = ArgType.getUnqualifiedType();
3841 // C++0x [temp.deduct.call]p4:
3842 // In general, the deduction process attempts to find template argument
3843 // values that will make the deduced A identical to A (after the type A
3844 // is transformed as described above). [...]
3845 TDF = TDF_SkipNonDependent;
3847 // - If the original P is a reference type, the deduced A (i.e., the
3848 // type referred to by the reference) can be more cv-qualified than
3849 // the transformed A.
3851 TDF |= TDF_ParamWithReferenceType;
3852 // - The transformed A can be another pointer or pointer to member
3853 // type that can be converted to the deduced A via a qualification
3854 // conversion (4.4).
3855 if (ArgType->isPointerType() || ArgType->isMemberPointerType() ||
3856 ArgType->isObjCObjectPointerType())
3857 TDF |= TDF_IgnoreQualifiers;
3858 // - If P is a class and P has the form simple-template-id, then the
3859 // transformed A can be a derived class of the deduced A. Likewise,
3860 // if P is a pointer to a class of the form simple-template-id, the
3861 // transformed A can be a pointer to a derived class pointed to by
3863 if (isSimpleTemplateIdType(ParamType) ||
3864 (isa<PointerType>(ParamType) &&
3865 isSimpleTemplateIdType(
3866 ParamType->getAs<PointerType>()->getPointeeType())))
3867 TDF |= TDF_DerivedClass;
3873 hasDeducibleTemplateParameters(Sema &S, FunctionTemplateDecl *FunctionTemplate,
3876 static Sema::TemplateDeductionResult DeduceTemplateArgumentsFromCallArgument(
3877 Sema &S, TemplateParameterList *TemplateParams, unsigned FirstInnerIndex,
3878 QualType ParamType, Expr *Arg, TemplateDeductionInfo &Info,
3879 SmallVectorImpl<DeducedTemplateArgument> &Deduced,
3880 SmallVectorImpl<Sema::OriginalCallArg> &OriginalCallArgs,
3881 bool DecomposedParam, unsigned ArgIdx, unsigned TDF);
3883 /// Attempt template argument deduction from an initializer list
3884 /// deemed to be an argument in a function call.
3885 static Sema::TemplateDeductionResult DeduceFromInitializerList(
3886 Sema &S, TemplateParameterList *TemplateParams, QualType AdjustedParamType,
3887 InitListExpr *ILE, TemplateDeductionInfo &Info,
3888 SmallVectorImpl<DeducedTemplateArgument> &Deduced,
3889 SmallVectorImpl<Sema::OriginalCallArg> &OriginalCallArgs, unsigned ArgIdx,
3891 // C++ [temp.deduct.call]p1: (CWG 1591)
3892 // If removing references and cv-qualifiers from P gives
3893 // std::initializer_list<P0> or P0[N] for some P0 and N and the argument is
3894 // a non-empty initializer list, then deduction is performed instead for
3895 // each element of the initializer list, taking P0 as a function template
3896 // parameter type and the initializer element as its argument
3898 // We've already removed references and cv-qualifiers here.
3899 if (!ILE->getNumInits())
3900 return Sema::TDK_Success;
3903 auto *ArrTy = S.Context.getAsArrayType(AdjustedParamType);
3905 ElTy = ArrTy->getElementType();
3906 else if (!S.isStdInitializerList(AdjustedParamType, &ElTy)) {
3907 // Otherwise, an initializer list argument causes the parameter to be
3908 // considered a non-deduced context
3909 return Sema::TDK_Success;
3912 // Resolving a core issue: a braced-init-list containing any designators is
3913 // a non-deduced context.
3914 for (Expr *E : ILE->inits())
3915 if (isa<DesignatedInitExpr>(E))
3916 return Sema::TDK_Success;
3918 // Deduction only needs to be done for dependent types.
3919 if (ElTy->isDependentType()) {
3920 for (Expr *E : ILE->inits()) {
3921 if (auto Result = DeduceTemplateArgumentsFromCallArgument(
3922 S, TemplateParams, 0, ElTy, E, Info, Deduced, OriginalCallArgs, true,
3928 // in the P0[N] case, if N is a non-type template parameter, N is deduced
3929 // from the length of the initializer list.
3930 if (auto *DependentArrTy = dyn_cast_or_null<DependentSizedArrayType>(ArrTy)) {
3931 // Determine the array bound is something we can deduce.
3932 if (NonTypeTemplateParmDecl *NTTP =
3933 getDeducedParameterFromExpr(Info, DependentArrTy->getSizeExpr())) {
3934 // We can perform template argument deduction for the given non-type
3935 // template parameter.
3936 // C++ [temp.deduct.type]p13:
3937 // The type of N in the type T[N] is std::size_t.
3938 QualType T = S.Context.getSizeType();
3939 llvm::APInt Size(S.Context.getIntWidth(T), ILE->getNumInits());
3940 if (auto Result = DeduceNonTypeTemplateArgument(
3941 S, TemplateParams, NTTP, llvm::APSInt(Size), T,
3942 /*ArrayBound=*/true, Info, Deduced))
3947 return Sema::TDK_Success;
3950 /// Perform template argument deduction per [temp.deduct.call] for a
3951 /// single parameter / argument pair.
3952 static Sema::TemplateDeductionResult DeduceTemplateArgumentsFromCallArgument(
3953 Sema &S, TemplateParameterList *TemplateParams, unsigned FirstInnerIndex,
3954 QualType ParamType, Expr *Arg, TemplateDeductionInfo &Info,
3955 SmallVectorImpl<DeducedTemplateArgument> &Deduced,
3956 SmallVectorImpl<Sema::OriginalCallArg> &OriginalCallArgs,
3957 bool DecomposedParam, unsigned ArgIdx, unsigned TDF) {
3958 QualType ArgType = Arg->getType();
3959 QualType OrigParamType = ParamType;
3961 // If P is a reference type [...]
3962 // If P is a cv-qualified type [...]
3963 if (AdjustFunctionParmAndArgTypesForDeduction(
3964 S, TemplateParams, FirstInnerIndex, ParamType, ArgType, Arg, TDF))
3965 return Sema::TDK_Success;
3967 // If [...] the argument is a non-empty initializer list [...]
3968 if (InitListExpr *ILE = dyn_cast<InitListExpr>(Arg))
3969 return DeduceFromInitializerList(S, TemplateParams, ParamType, ILE, Info,
3970 Deduced, OriginalCallArgs, ArgIdx, TDF);
3972 // [...] the deduction process attempts to find template argument values
3973 // that will make the deduced A identical to A
3975 // Keep track of the argument type and corresponding parameter index,
3976 // so we can check for compatibility between the deduced A and A.
3977 OriginalCallArgs.push_back(
3978 Sema::OriginalCallArg(OrigParamType, DecomposedParam, ArgIdx, ArgType));
3979 return DeduceTemplateArgumentsByTypeMatch(S, TemplateParams, ParamType,
3980 ArgType, Info, Deduced, TDF);
3983 /// Perform template argument deduction from a function call
3984 /// (C++ [temp.deduct.call]).
3986 /// \param FunctionTemplate the function template for which we are performing
3987 /// template argument deduction.
3989 /// \param ExplicitTemplateArgs the explicit template arguments provided
3992 /// \param Args the function call arguments
3994 /// \param Specialization if template argument deduction was successful,
3995 /// this will be set to the function template specialization produced by
3996 /// template argument deduction.
3998 /// \param Info the argument will be updated to provide additional information
3999 /// about template argument deduction.
4001 /// \param CheckNonDependent A callback to invoke to check conversions for
4002 /// non-dependent parameters, between deduction and substitution, per DR1391.
4003 /// If this returns true, substitution will be skipped and we return
4004 /// TDK_NonDependentConversionFailure. The callback is passed the parameter
4005 /// types (after substituting explicit template arguments).
4007 /// \returns the result of template argument deduction.
4008 Sema::TemplateDeductionResult Sema::DeduceTemplateArguments(
4009 FunctionTemplateDecl *FunctionTemplate,
4010 TemplateArgumentListInfo *ExplicitTemplateArgs, ArrayRef<Expr *> Args,
4011 FunctionDecl *&Specialization, TemplateDeductionInfo &Info,
4012 bool PartialOverloading,
4013 llvm::function_ref<bool(ArrayRef<QualType>)> CheckNonDependent) {
4014 if (FunctionTemplate->isInvalidDecl())
4017 FunctionDecl *Function = FunctionTemplate->getTemplatedDecl();
4018 unsigned NumParams = Function->getNumParams();
4020 unsigned FirstInnerIndex = getFirstInnerIndex(FunctionTemplate);
4022 // C++ [temp.deduct.call]p1:
4023 // Template argument deduction is done by comparing each function template
4024 // parameter type (call it P) with the type of the corresponding argument
4025 // of the call (call it A) as described below.
4026 if (Args.size() < Function->getMinRequiredArguments() && !PartialOverloading)
4027 return TDK_TooFewArguments;
4028 else if (TooManyArguments(NumParams, Args.size(), PartialOverloading)) {
4029 const auto *Proto = Function->getType()->castAs<FunctionProtoType>();
4030 if (Proto->isTemplateVariadic())
4032 else if (!Proto->isVariadic())
4033 return TDK_TooManyArguments;
4036 // The types of the parameters from which we will perform template argument
4038 LocalInstantiationScope InstScope(*this);
4039 TemplateParameterList *TemplateParams
4040 = FunctionTemplate->getTemplateParameters();
4041 SmallVector<DeducedTemplateArgument, 4> Deduced;
4042 SmallVector<QualType, 8> ParamTypes;
4043 unsigned NumExplicitlySpecified = 0;
4044 if (ExplicitTemplateArgs) {
4045 TemplateDeductionResult Result;
4046 runWithSufficientStackSpace(Info.getLocation(), [&] {
4047 Result = SubstituteExplicitTemplateArguments(
4048 FunctionTemplate, *ExplicitTemplateArgs, Deduced, ParamTypes, nullptr,
4054 NumExplicitlySpecified = Deduced.size();
4056 // Just fill in the parameter types from the function declaration.
4057 for (unsigned I = 0; I != NumParams; ++I)
4058 ParamTypes.push_back(Function->getParamDecl(I)->getType());
4061 SmallVector<OriginalCallArg, 8> OriginalCallArgs;
4063 // Deduce an argument of type ParamType from an expression with index ArgIdx.
4064 auto DeduceCallArgument = [&](QualType ParamType, unsigned ArgIdx) {
4065 // C++ [demp.deduct.call]p1: (DR1391)
4066 // Template argument deduction is done by comparing each function template
4067 // parameter that contains template-parameters that participate in
4068 // template argument deduction ...
4069 if (!hasDeducibleTemplateParameters(*this, FunctionTemplate, ParamType))
4070 return Sema::TDK_Success;
4072 // ... with the type of the corresponding argument
4073 return DeduceTemplateArgumentsFromCallArgument(
4074 *this, TemplateParams, FirstInnerIndex, ParamType, Args[ArgIdx], Info, Deduced,
4075 OriginalCallArgs, /*Decomposed*/false, ArgIdx, /*TDF*/ 0);
4078 // Deduce template arguments from the function parameters.
4079 Deduced.resize(TemplateParams->size());
4080 SmallVector<QualType, 8> ParamTypesForArgChecking;
4081 for (unsigned ParamIdx = 0, NumParamTypes = ParamTypes.size(), ArgIdx = 0;
4082 ParamIdx != NumParamTypes; ++ParamIdx) {
4083 QualType ParamType = ParamTypes[ParamIdx];
4085 const PackExpansionType *ParamExpansion =
4086 dyn_cast<PackExpansionType>(ParamType);
4087 if (!ParamExpansion) {
4088 // Simple case: matching a function parameter to a function argument.
4089 if (ArgIdx >= Args.size())
4092 ParamTypesForArgChecking.push_back(ParamType);
4093 if (auto Result = DeduceCallArgument(ParamType, ArgIdx++))
4099 QualType ParamPattern = ParamExpansion->getPattern();
4100 PackDeductionScope PackScope(*this, TemplateParams, Deduced, Info,
4103 // C++0x [temp.deduct.call]p1:
4104 // For a function parameter pack that occurs at the end of the
4105 // parameter-declaration-list, the type A of each remaining argument of
4106 // the call is compared with the type P of the declarator-id of the
4107 // function parameter pack. Each comparison deduces template arguments
4108 // for subsequent positions in the template parameter packs expanded by
4109 // the function parameter pack. When a function parameter pack appears
4110 // in a non-deduced context [not at the end of the list], the type of
4111 // that parameter pack is never deduced.
4113 // FIXME: The above rule allows the size of the parameter pack to change
4114 // after we skip it (in the non-deduced case). That makes no sense, so
4115 // we instead notionally deduce the pack against N arguments, where N is
4116 // the length of the explicitly-specified pack if it's expanded by the
4117 // parameter pack and 0 otherwise, and we treat each deduction as a
4118 // non-deduced context.
4119 if (ParamIdx + 1 == NumParamTypes || PackScope.hasFixedArity()) {
4120 for (; ArgIdx < Args.size() && PackScope.hasNextElement();
4121 PackScope.nextPackElement(), ++ArgIdx) {
4122 ParamTypesForArgChecking.push_back(ParamPattern);
4123 if (auto Result = DeduceCallArgument(ParamPattern, ArgIdx))
4127 // If the parameter type contains an explicitly-specified pack that we
4128 // could not expand, skip the number of parameters notionally created
4129 // by the expansion.
4130 Optional<unsigned> NumExpansions = ParamExpansion->getNumExpansions();
4131 if (NumExpansions && !PackScope.isPartiallyExpanded()) {
4132 for (unsigned I = 0; I != *NumExpansions && ArgIdx < Args.size();
4134 ParamTypesForArgChecking.push_back(ParamPattern);
4135 // FIXME: Should we add OriginalCallArgs for these? What if the
4136 // corresponding argument is a list?
4137 PackScope.nextPackElement();
4142 // Build argument packs for each of the parameter packs expanded by this
4144 if (auto Result = PackScope.finish())
4148 // Capture the context in which the function call is made. This is the context
4149 // that is needed when the accessibility of template arguments is checked.
4150 DeclContext *CallingCtx = CurContext;
4152 TemplateDeductionResult Result;
4153 runWithSufficientStackSpace(Info.getLocation(), [&] {
4154 Result = FinishTemplateArgumentDeduction(
4155 FunctionTemplate, Deduced, NumExplicitlySpecified, Specialization, Info,
4156 &OriginalCallArgs, PartialOverloading, [&, CallingCtx]() {
4157 ContextRAII SavedContext(*this, CallingCtx);
4158 return CheckNonDependent(ParamTypesForArgChecking);
4164 QualType Sema::adjustCCAndNoReturn(QualType ArgFunctionType,
4165 QualType FunctionType,
4166 bool AdjustExceptionSpec) {
4167 if (ArgFunctionType.isNull())
4168 return ArgFunctionType;
4170 const auto *FunctionTypeP = FunctionType->castAs<FunctionProtoType>();
4171 const auto *ArgFunctionTypeP = ArgFunctionType->castAs<FunctionProtoType>();
4172 FunctionProtoType::ExtProtoInfo EPI = ArgFunctionTypeP->getExtProtoInfo();
4173 bool Rebuild = false;
4175 CallingConv CC = FunctionTypeP->getCallConv();
4176 if (EPI.ExtInfo.getCC() != CC) {
4177 EPI.ExtInfo = EPI.ExtInfo.withCallingConv(CC);
4181 bool NoReturn = FunctionTypeP->getNoReturnAttr();
4182 if (EPI.ExtInfo.getNoReturn() != NoReturn) {
4183 EPI.ExtInfo = EPI.ExtInfo.withNoReturn(NoReturn);
4187 if (AdjustExceptionSpec && (FunctionTypeP->hasExceptionSpec() ||
4188 ArgFunctionTypeP->hasExceptionSpec())) {
4189 EPI.ExceptionSpec = FunctionTypeP->getExtProtoInfo().ExceptionSpec;
4194 return ArgFunctionType;
4196 return Context.getFunctionType(ArgFunctionTypeP->getReturnType(),
4197 ArgFunctionTypeP->getParamTypes(), EPI);
4200 /// Deduce template arguments when taking the address of a function
4201 /// template (C++ [temp.deduct.funcaddr]) or matching a specialization to
4204 /// \param FunctionTemplate the function template for which we are performing
4205 /// template argument deduction.
4207 /// \param ExplicitTemplateArgs the explicitly-specified template
4210 /// \param ArgFunctionType the function type that will be used as the
4211 /// "argument" type (A) when performing template argument deduction from the
4212 /// function template's function type. This type may be NULL, if there is no
4213 /// argument type to compare against, in C++0x [temp.arg.explicit]p3.
4215 /// \param Specialization if template argument deduction was successful,
4216 /// this will be set to the function template specialization produced by
4217 /// template argument deduction.
4219 /// \param Info the argument will be updated to provide additional information
4220 /// about template argument deduction.
4222 /// \param IsAddressOfFunction If \c true, we are deducing as part of taking
4223 /// the address of a function template per [temp.deduct.funcaddr] and
4224 /// [over.over]. If \c false, we are looking up a function template
4225 /// specialization based on its signature, per [temp.deduct.decl].
4227 /// \returns the result of template argument deduction.
4228 Sema::TemplateDeductionResult Sema::DeduceTemplateArguments(
4229 FunctionTemplateDecl *FunctionTemplate,
4230 TemplateArgumentListInfo *ExplicitTemplateArgs, QualType ArgFunctionType,
4231 FunctionDecl *&Specialization, TemplateDeductionInfo &Info,
4232 bool IsAddressOfFunction) {
4233 if (FunctionTemplate->isInvalidDecl())
4236 FunctionDecl *Function = FunctionTemplate->getTemplatedDecl();
4237 TemplateParameterList *TemplateParams
4238 = FunctionTemplate->getTemplateParameters();
4239 QualType FunctionType = Function->getType();
4241 // Substitute any explicit template arguments.
4242 LocalInstantiationScope InstScope(*this);
4243 SmallVector<DeducedTemplateArgument, 4> Deduced;
4244 unsigned NumExplicitlySpecified = 0;
4245 SmallVector<QualType, 4> ParamTypes;
4246 if (ExplicitTemplateArgs) {
4247 TemplateDeductionResult Result;
4248 runWithSufficientStackSpace(Info.getLocation(), [&] {
4249 Result = SubstituteExplicitTemplateArguments(
4250 FunctionTemplate, *ExplicitTemplateArgs, Deduced, ParamTypes,
4251 &FunctionType, Info);
4256 NumExplicitlySpecified = Deduced.size();
4259 // When taking the address of a function, we require convertibility of
4260 // the resulting function type. Otherwise, we allow arbitrary mismatches
4261 // of calling convention and noreturn.
4262 if (!IsAddressOfFunction)
4263 ArgFunctionType = adjustCCAndNoReturn(ArgFunctionType, FunctionType,
4264 /*AdjustExceptionSpec*/false);
4266 // Unevaluated SFINAE context.
4267 EnterExpressionEvaluationContext Unevaluated(
4268 *this, Sema::ExpressionEvaluationContext::Unevaluated);
4269 SFINAETrap Trap(*this);
4271 Deduced.resize(TemplateParams->size());
4273 // If the function has a deduced return type, substitute it for a dependent
4274 // type so that we treat it as a non-deduced context in what follows. If we
4275 // are looking up by signature, the signature type should also have a deduced
4276 // return type, which we instead expect to exactly match.
4277 bool HasDeducedReturnType = false;
4278 if (getLangOpts().CPlusPlus14 && IsAddressOfFunction &&
4279 Function->getReturnType()->getContainedAutoType()) {
4280 FunctionType = SubstAutoType(FunctionType, Context.DependentTy);
4281 HasDeducedReturnType = true;
4284 if (!ArgFunctionType.isNull()) {
4286 TDF_TopLevelParameterTypeList | TDF_AllowCompatibleFunctionType;
4287 // Deduce template arguments from the function type.
4288 if (TemplateDeductionResult Result
4289 = DeduceTemplateArgumentsByTypeMatch(*this, TemplateParams,
4290 FunctionType, ArgFunctionType,
4291 Info, Deduced, TDF))
4295 TemplateDeductionResult Result;
4296 runWithSufficientStackSpace(Info.getLocation(), [&] {
4297 Result = FinishTemplateArgumentDeduction(FunctionTemplate, Deduced,
4298 NumExplicitlySpecified,
4299 Specialization, Info);
4304 // If the function has a deduced return type, deduce it now, so we can check
4305 // that the deduced function type matches the requested type.
4306 if (HasDeducedReturnType &&
4307 Specialization->getReturnType()->isUndeducedType() &&
4308 DeduceReturnType(Specialization, Info.getLocation(), false))
4309 return TDK_MiscellaneousDeductionFailure;
4311 // If the function has a dependent exception specification, resolve it now,
4312 // so we can check that the exception specification matches.
4313 auto *SpecializationFPT =
4314 Specialization->getType()->castAs<FunctionProtoType>();
4315 if (getLangOpts().CPlusPlus17 &&
4316 isUnresolvedExceptionSpec(SpecializationFPT->getExceptionSpecType()) &&
4317 !ResolveExceptionSpec(Info.getLocation(), SpecializationFPT))
4318 return TDK_MiscellaneousDeductionFailure;
4320 // Adjust the exception specification of the argument to match the
4321 // substituted and resolved type we just formed. (Calling convention and
4322 // noreturn can't be dependent, so we don't actually need this for them
4324 QualType SpecializationType = Specialization->getType();
4325 if (!IsAddressOfFunction)
4326 ArgFunctionType = adjustCCAndNoReturn(ArgFunctionType, SpecializationType,
4327 /*AdjustExceptionSpec*/true);
4329 // If the requested function type does not match the actual type of the
4330 // specialization with respect to arguments of compatible pointer to function
4331 // types, template argument deduction fails.
4332 if (!ArgFunctionType.isNull()) {
4333 if (IsAddressOfFunction &&
4334 !isSameOrCompatibleFunctionType(
4335 Context.getCanonicalType(SpecializationType),
4336 Context.getCanonicalType(ArgFunctionType)))
4337 return TDK_MiscellaneousDeductionFailure;
4339 if (!IsAddressOfFunction &&
4340 !Context.hasSameType(SpecializationType, ArgFunctionType))
4341 return TDK_MiscellaneousDeductionFailure;
4347 /// Deduce template arguments for a templated conversion
4348 /// function (C++ [temp.deduct.conv]) and, if successful, produce a
4349 /// conversion function template specialization.
4350 Sema::TemplateDeductionResult
4351 Sema::DeduceTemplateArguments(FunctionTemplateDecl *ConversionTemplate,
4353 CXXConversionDecl *&Specialization,
4354 TemplateDeductionInfo &Info) {
4355 if (ConversionTemplate->isInvalidDecl())
4358 CXXConversionDecl *ConversionGeneric
4359 = cast<CXXConversionDecl>(ConversionTemplate->getTemplatedDecl());
4361 QualType FromType = ConversionGeneric->getConversionType();
4363 // Canonicalize the types for deduction.
4364 QualType P = Context.getCanonicalType(FromType);
4365 QualType A = Context.getCanonicalType(ToType);
4367 // C++0x [temp.deduct.conv]p2:
4368 // If P is a reference type, the type referred to by P is used for
4370 if (const ReferenceType *PRef = P->getAs<ReferenceType>())
4371 P = PRef->getPointeeType();
4373 // C++0x [temp.deduct.conv]p4:
4374 // [...] If A is a reference type, the type referred to by A is used
4375 // for type deduction.
4376 if (const ReferenceType *ARef = A->getAs<ReferenceType>()) {
4377 A = ARef->getPointeeType();
4378 // We work around a defect in the standard here: cv-qualifiers are also
4379 // removed from P and A in this case, unless P was a reference type. This
4380 // seems to mostly match what other compilers are doing.
4381 if (!FromType->getAs<ReferenceType>()) {
4382 A = A.getUnqualifiedType();
4383 P = P.getUnqualifiedType();
4386 // C++ [temp.deduct.conv]p3:
4388 // If A is not a reference type:
4390 assert(!A->isReferenceType() && "Reference types were handled above");
4392 // - If P is an array type, the pointer type produced by the
4393 // array-to-pointer standard conversion (4.2) is used in place
4394 // of P for type deduction; otherwise,
4395 if (P->isArrayType())
4396 P = Context.getArrayDecayedType(P);
4397 // - If P is a function type, the pointer type produced by the
4398 // function-to-pointer standard conversion (4.3) is used in
4399 // place of P for type deduction; otherwise,
4400 else if (P->isFunctionType())
4401 P = Context.getPointerType(P);
4402 // - If P is a cv-qualified type, the top level cv-qualifiers of
4403 // P's type are ignored for type deduction.
4405 P = P.getUnqualifiedType();
4407 // C++0x [temp.deduct.conv]p4:
4408 // If A is a cv-qualified type, the top level cv-qualifiers of A's
4409 // type are ignored for type deduction. If A is a reference type, the type
4410 // referred to by A is used for type deduction.
4411 A = A.getUnqualifiedType();
4414 // Unevaluated SFINAE context.
4415 EnterExpressionEvaluationContext Unevaluated(
4416 *this, Sema::ExpressionEvaluationContext::Unevaluated);
4417 SFINAETrap Trap(*this);
4419 // C++ [temp.deduct.conv]p1:
4420 // Template argument deduction is done by comparing the return
4421 // type of the template conversion function (call it P) with the
4422 // type that is required as the result of the conversion (call it
4423 // A) as described in 14.8.2.4.
4424 TemplateParameterList *TemplateParams
4425 = ConversionTemplate->getTemplateParameters();
4426 SmallVector<DeducedTemplateArgument, 4> Deduced;
4427 Deduced.resize(TemplateParams->size());
4429 // C++0x [temp.deduct.conv]p4:
4430 // In general, the deduction process attempts to find template
4431 // argument values that will make the deduced A identical to
4432 // A. However, there are two cases that allow a difference:
4434 // - If the original A is a reference type, A can be more
4435 // cv-qualified than the deduced A (i.e., the type referred to
4436 // by the reference)
4437 if (ToType->isReferenceType())
4438 TDF |= TDF_ArgWithReferenceType;
4439 // - The deduced A can be another pointer or pointer to member
4440 // type that can be converted to A via a qualification
4443 // (C++0x [temp.deduct.conv]p6 clarifies that this only happens when
4444 // both P and A are pointers or member pointers. In this case, we
4445 // just ignore cv-qualifiers completely).
4446 if ((P->isPointerType() && A->isPointerType()) ||
4447 (P->isMemberPointerType() && A->isMemberPointerType()))
4448 TDF |= TDF_IgnoreQualifiers;
4449 if (TemplateDeductionResult Result
4450 = DeduceTemplateArgumentsByTypeMatch(*this, TemplateParams,
4451 P, A, Info, Deduced, TDF))
4454 // Create an Instantiation Scope for finalizing the operator.
4455 LocalInstantiationScope InstScope(*this);
4456 // Finish template argument deduction.
4457 FunctionDecl *ConversionSpecialized = nullptr;
4458 TemplateDeductionResult Result;
4459 runWithSufficientStackSpace(Info.getLocation(), [&] {
4460 Result = FinishTemplateArgumentDeduction(ConversionTemplate, Deduced, 0,
4461 ConversionSpecialized, Info);
4463 Specialization = cast_or_null<CXXConversionDecl>(ConversionSpecialized);
4467 /// Deduce template arguments for a function template when there is
4468 /// nothing to deduce against (C++0x [temp.arg.explicit]p3).
4470 /// \param FunctionTemplate the function template for which we are performing
4471 /// template argument deduction.
4473 /// \param ExplicitTemplateArgs the explicitly-specified template
4476 /// \param Specialization if template argument deduction was successful,
4477 /// this will be set to the function template specialization produced by
4478 /// template argument deduction.
4480 /// \param Info the argument will be updated to provide additional information
4481 /// about template argument deduction.
4483 /// \param IsAddressOfFunction If \c true, we are deducing as part of taking
4484 /// the address of a function template in a context where we do not have a
4485 /// target type, per [over.over]. If \c false, we are looking up a function
4486 /// template specialization based on its signature, which only happens when
4487 /// deducing a function parameter type from an argument that is a template-id
4488 /// naming a function template specialization.
4490 /// \returns the result of template argument deduction.
4491 Sema::TemplateDeductionResult Sema::DeduceTemplateArguments(
4492 FunctionTemplateDecl *FunctionTemplate,
4493 TemplateArgumentListInfo *ExplicitTemplateArgs,
4494 FunctionDecl *&Specialization, TemplateDeductionInfo &Info,
4495 bool IsAddressOfFunction) {
4496 return DeduceTemplateArguments(FunctionTemplate, ExplicitTemplateArgs,
4497 QualType(), Specialization, Info,
4498 IsAddressOfFunction);
4502 struct DependentAuto { bool IsPack; };
4504 /// Substitute the 'auto' specifier or deduced template specialization type
4505 /// specifier within a type for a given replacement type.
4506 class SubstituteDeducedTypeTransform :
4507 public TreeTransform<SubstituteDeducedTypeTransform> {
4508 QualType Replacement;
4509 bool ReplacementIsPack;
4513 SubstituteDeducedTypeTransform(Sema &SemaRef, DependentAuto DA)
4514 : TreeTransform<SubstituteDeducedTypeTransform>(SemaRef), Replacement(),
4515 ReplacementIsPack(DA.IsPack), UseTypeSugar(true) {}
4517 SubstituteDeducedTypeTransform(Sema &SemaRef, QualType Replacement,
4518 bool UseTypeSugar = true)
4519 : TreeTransform<SubstituteDeducedTypeTransform>(SemaRef),
4520 Replacement(Replacement), ReplacementIsPack(false),
4521 UseTypeSugar(UseTypeSugar) {}
4523 QualType TransformDesugared(TypeLocBuilder &TLB, DeducedTypeLoc TL) {
4524 assert(isa<TemplateTypeParmType>(Replacement) &&
4525 "unexpected unsugared replacement kind");
4526 QualType Result = Replacement;
4527 TemplateTypeParmTypeLoc NewTL = TLB.push<TemplateTypeParmTypeLoc>(Result);
4528 NewTL.setNameLoc(TL.getNameLoc());
4532 QualType TransformAutoType(TypeLocBuilder &TLB, AutoTypeLoc TL) {
4533 // If we're building the type pattern to deduce against, don't wrap the
4534 // substituted type in an AutoType. Certain template deduction rules
4535 // apply only when a template type parameter appears directly (and not if
4536 // the parameter is found through desugaring). For instance:
4537 // auto &&lref = lvalue;
4538 // must transform into "rvalue reference to T" not "rvalue reference to
4539 // auto type deduced as T" in order for [temp.deduct.call]p3 to apply.
4541 // FIXME: Is this still necessary?
4543 return TransformDesugared(TLB, TL);
4545 QualType Result = SemaRef.Context.getAutoType(
4546 Replacement, TL.getTypePtr()->getKeyword(), Replacement.isNull(),
4547 ReplacementIsPack, TL.getTypePtr()->getTypeConstraintConcept(),
4548 TL.getTypePtr()->getTypeConstraintArguments());
4549 auto NewTL = TLB.push<AutoTypeLoc>(Result);
4554 QualType TransformDeducedTemplateSpecializationType(
4555 TypeLocBuilder &TLB, DeducedTemplateSpecializationTypeLoc TL) {
4557 return TransformDesugared(TLB, TL);
4559 QualType Result = SemaRef.Context.getDeducedTemplateSpecializationType(
4560 TL.getTypePtr()->getTemplateName(),
4561 Replacement, Replacement.isNull());
4562 auto NewTL = TLB.push<DeducedTemplateSpecializationTypeLoc>(Result);
4563 NewTL.setNameLoc(TL.getNameLoc());
4567 ExprResult TransformLambdaExpr(LambdaExpr *E) {
4568 // Lambdas never need to be transformed.
4572 QualType Apply(TypeLoc TL) {
4573 // Create some scratch storage for the transformed type locations.
4574 // FIXME: We're just going to throw this information away. Don't build it.
4576 TLB.reserve(TL.getFullDataSize());
4577 return TransformType(TLB, TL);
4583 Sema::DeduceAutoResult
4584 Sema::DeduceAutoType(TypeSourceInfo *Type, Expr *&Init, QualType &Result,
4585 Optional<unsigned> DependentDeductionDepth,
4586 bool IgnoreConstraints) {
4587 return DeduceAutoType(Type->getTypeLoc(), Init, Result,
4588 DependentDeductionDepth, IgnoreConstraints);
4591 /// Attempt to produce an informative diagostic explaining why auto deduction
4593 /// \return \c true if diagnosed, \c false if not.
4594 static bool diagnoseAutoDeductionFailure(Sema &S,
4595 Sema::TemplateDeductionResult TDK,
4596 TemplateDeductionInfo &Info,
4597 ArrayRef<SourceRange> Ranges) {
4599 case Sema::TDK_Inconsistent: {
4600 // Inconsistent deduction means we were deducing from an initializer list.
4601 auto D = S.Diag(Info.getLocation(), diag::err_auto_inconsistent_deduction);
4602 D << Info.FirstArg << Info.SecondArg;
4603 for (auto R : Ranges)
4608 // FIXME: Are there other cases for which a custom diagnostic is more useful
4609 // than the basic "types don't match" diagnostic?
4616 static Sema::DeduceAutoResult
4617 CheckDeducedPlaceholderConstraints(Sema &S, const AutoType &Type,
4618 AutoTypeLoc TypeLoc, QualType Deduced) {
4619 ConstraintSatisfaction Satisfaction;
4620 ConceptDecl *Concept = Type.getTypeConstraintConcept();
4621 TemplateArgumentListInfo TemplateArgs(TypeLoc.getLAngleLoc(),
4622 TypeLoc.getRAngleLoc());
4623 TemplateArgs.addArgument(
4624 TemplateArgumentLoc(TemplateArgument(Deduced),
4625 S.Context.getTrivialTypeSourceInfo(
4626 Deduced, TypeLoc.getNameLoc())));
4627 for (unsigned I = 0, C = TypeLoc.getNumArgs(); I != C; ++I)
4628 TemplateArgs.addArgument(TypeLoc.getArgLoc(I));
4630 llvm::SmallVector<TemplateArgument, 4> Converted;
4631 if (S.CheckTemplateArgumentList(Concept, SourceLocation(), TemplateArgs,
4632 /*PartialTemplateArgs=*/false, Converted))
4633 return Sema::DAR_FailedAlreadyDiagnosed;
4634 if (S.CheckConstraintSatisfaction(Concept, {Concept->getConstraintExpr()},
4635 Converted, TypeLoc.getLocalSourceRange(),
4637 return Sema::DAR_FailedAlreadyDiagnosed;
4638 if (!Satisfaction.IsSatisfied) {
4640 llvm::raw_string_ostream OS(Buf);
4641 OS << "'" << Concept->getName();
4642 if (TypeLoc.hasExplicitTemplateArgs()) {
4644 for (const auto &Arg : Type.getTypeConstraintArguments())
4645 Arg.print(S.getPrintingPolicy(), OS);
4650 S.Diag(TypeLoc.getConceptNameLoc(),
4651 diag::err_placeholder_constraints_not_satisfied)
4652 << Deduced << Buf << TypeLoc.getLocalSourceRange();
4653 S.DiagnoseUnsatisfiedConstraint(Satisfaction);
4654 return Sema::DAR_FailedAlreadyDiagnosed;
4656 return Sema::DAR_Succeeded;
4659 /// Deduce the type for an auto type-specifier (C++11 [dcl.spec.auto]p6)
4661 /// Note that this is done even if the initializer is dependent. (This is
4662 /// necessary to support partial ordering of templates using 'auto'.)
4663 /// A dependent type will be produced when deducing from a dependent type.
4665 /// \param Type the type pattern using the auto type-specifier.
4666 /// \param Init the initializer for the variable whose type is to be deduced.
4667 /// \param Result if type deduction was successful, this will be set to the
4669 /// \param DependentDeductionDepth Set if we should permit deduction in
4670 /// dependent cases. This is necessary for template partial ordering with
4671 /// 'auto' template parameters. The value specified is the template
4672 /// parameter depth at which we should perform 'auto' deduction.
4673 /// \param IgnoreConstraints Set if we should not fail if the deduced type does
4674 /// not satisfy the type-constraint in the auto type.
4675 Sema::DeduceAutoResult
4676 Sema::DeduceAutoType(TypeLoc Type, Expr *&Init, QualType &Result,
4677 Optional<unsigned> DependentDeductionDepth,
4678 bool IgnoreConstraints) {
4679 if (Init->containsErrors())
4680 return DAR_FailedAlreadyDiagnosed;
4681 if (Init->getType()->isNonOverloadPlaceholderType()) {
4682 ExprResult NonPlaceholder = CheckPlaceholderExpr(Init);
4683 if (NonPlaceholder.isInvalid())
4684 return DAR_FailedAlreadyDiagnosed;
4685 Init = NonPlaceholder.get();
4688 DependentAuto DependentResult = {
4689 /*.IsPack = */ (bool)Type.getAs<PackExpansionTypeLoc>()};
4691 if (!DependentDeductionDepth &&
4692 (Type.getType()->isDependentType() || Init->isTypeDependent() ||
4693 Init->containsUnexpandedParameterPack())) {
4694 Result = SubstituteDeducedTypeTransform(*this, DependentResult).Apply(Type);
4695 assert(!Result.isNull() && "substituting DependentTy can't fail");
4696 return DAR_Succeeded;
4699 // Find the depth of template parameter to synthesize.
4700 unsigned Depth = DependentDeductionDepth.getValueOr(0);
4702 // If this is a 'decltype(auto)' specifier, do the decltype dance.
4703 // Since 'decltype(auto)' can only occur at the top of the type, we
4704 // don't need to go digging for it.
4705 if (const AutoType *AT = Type.getType()->getAs<AutoType>()) {
4706 if (AT->isDecltypeAuto()) {
4707 if (isa<InitListExpr>(Init)) {
4708 Diag(Init->getBeginLoc(), diag::err_decltype_auto_initializer_list);
4709 return DAR_FailedAlreadyDiagnosed;
4712 ExprResult ER = CheckPlaceholderExpr(Init);
4714 return DAR_FailedAlreadyDiagnosed;
4716 QualType Deduced = BuildDecltypeType(Init, Init->getBeginLoc(), false);
4717 if (Deduced.isNull())
4718 return DAR_FailedAlreadyDiagnosed;
4719 // FIXME: Support a non-canonical deduced type for 'auto'.
4720 Deduced = Context.getCanonicalType(Deduced);
4721 if (AT->isConstrained() && !IgnoreConstraints) {
4722 auto ConstraintsResult =
4723 CheckDeducedPlaceholderConstraints(*this, *AT,
4724 Type.getContainedAutoTypeLoc(),
4726 if (ConstraintsResult != DAR_Succeeded)
4727 return ConstraintsResult;
4729 Result = SubstituteDeducedTypeTransform(*this, Deduced).Apply(Type);
4730 if (Result.isNull())
4731 return DAR_FailedAlreadyDiagnosed;
4732 return DAR_Succeeded;
4733 } else if (!getLangOpts().CPlusPlus) {
4734 if (isa<InitListExpr>(Init)) {
4735 Diag(Init->getBeginLoc(), diag::err_auto_init_list_from_c);
4736 return DAR_FailedAlreadyDiagnosed;
4741 SourceLocation Loc = Init->getExprLoc();
4743 LocalInstantiationScope InstScope(*this);
4745 // Build template<class TemplParam> void Func(FuncParam);
4746 TemplateTypeParmDecl *TemplParam = TemplateTypeParmDecl::Create(
4747 Context, nullptr, SourceLocation(), Loc, Depth, 0, nullptr, false, false,
4749 QualType TemplArg = QualType(TemplParam->getTypeForDecl(), 0);
4750 NamedDecl *TemplParamPtr = TemplParam;
4751 FixedSizeTemplateParameterListStorage<1, false> TemplateParamsSt(
4752 Context, Loc, Loc, TemplParamPtr, Loc, nullptr);
4754 QualType FuncParam =
4755 SubstituteDeducedTypeTransform(*this, TemplArg, /*UseTypeSugar*/false)
4757 assert(!FuncParam.isNull() &&
4758 "substituting template parameter for 'auto' failed");
4760 // Deduce type of TemplParam in Func(Init)
4761 SmallVector<DeducedTemplateArgument, 1> Deduced;
4764 TemplateDeductionInfo Info(Loc, Depth);
4766 // If deduction failed, don't diagnose if the initializer is dependent; it
4767 // might acquire a matching type in the instantiation.
4768 auto DeductionFailed = [&](TemplateDeductionResult TDK,
4769 ArrayRef<SourceRange> Ranges) -> DeduceAutoResult {
4770 if (Init->isTypeDependent()) {
4772 SubstituteDeducedTypeTransform(*this, DependentResult).Apply(Type);
4773 assert(!Result.isNull() && "substituting DependentTy can't fail");
4774 return DAR_Succeeded;
4776 if (diagnoseAutoDeductionFailure(*this, TDK, Info, Ranges))
4777 return DAR_FailedAlreadyDiagnosed;
4781 SmallVector<OriginalCallArg, 4> OriginalCallArgs;
4783 InitListExpr *InitList = dyn_cast<InitListExpr>(Init);
4785 // Notionally, we substitute std::initializer_list<T> for 'auto' and deduce
4786 // against that. Such deduction only succeeds if removing cv-qualifiers and
4787 // references results in std::initializer_list<T>.
4788 if (!Type.getType().getNonReferenceType()->getAs<AutoType>())
4791 // Resolving a core issue: a braced-init-list containing any designators is
4792 // a non-deduced context.
4793 for (Expr *E : InitList->inits())
4794 if (isa<DesignatedInitExpr>(E))
4797 SourceRange DeducedFromInitRange;
4798 for (unsigned i = 0, e = InitList->getNumInits(); i < e; ++i) {
4799 Expr *Init = InitList->getInit(i);
4801 if (auto TDK = DeduceTemplateArgumentsFromCallArgument(
4802 *this, TemplateParamsSt.get(), 0, TemplArg, Init,
4803 Info, Deduced, OriginalCallArgs, /*Decomposed*/ true,
4804 /*ArgIdx*/ 0, /*TDF*/ 0))
4805 return DeductionFailed(TDK, {DeducedFromInitRange,
4806 Init->getSourceRange()});
4808 if (DeducedFromInitRange.isInvalid() &&
4809 Deduced[0].getKind() != TemplateArgument::Null)
4810 DeducedFromInitRange = Init->getSourceRange();
4813 if (!getLangOpts().CPlusPlus && Init->refersToBitField()) {
4814 Diag(Loc, diag::err_auto_bitfield);
4815 return DAR_FailedAlreadyDiagnosed;
4818 if (auto TDK = DeduceTemplateArgumentsFromCallArgument(
4819 *this, TemplateParamsSt.get(), 0, FuncParam, Init, Info, Deduced,
4820 OriginalCallArgs, /*Decomposed*/ false, /*ArgIdx*/ 0, /*TDF*/ 0))
4821 return DeductionFailed(TDK, {});
4824 // Could be null if somehow 'auto' appears in a non-deduced context.
4825 if (Deduced[0].getKind() != TemplateArgument::Type)
4826 return DeductionFailed(TDK_Incomplete, {});
4828 QualType DeducedType = Deduced[0].getAsType();
4831 DeducedType = BuildStdInitializerList(DeducedType, Loc);
4832 if (DeducedType.isNull())
4833 return DAR_FailedAlreadyDiagnosed;
4836 if (const auto *AT = Type.getType()->getAs<AutoType>()) {
4837 if (AT->isConstrained() && !IgnoreConstraints) {
4838 auto ConstraintsResult =
4839 CheckDeducedPlaceholderConstraints(*this, *AT,
4840 Type.getContainedAutoTypeLoc(),
4842 if (ConstraintsResult != DAR_Succeeded)
4843 return ConstraintsResult;
4847 Result = SubstituteDeducedTypeTransform(*this, DeducedType).Apply(Type);
4848 if (Result.isNull())
4849 return DAR_FailedAlreadyDiagnosed;
4851 // Check that the deduced argument type is compatible with the original
4852 // argument type per C++ [temp.deduct.call]p4.
4853 QualType DeducedA = InitList ? Deduced[0].getAsType() : Result;
4854 for (const OriginalCallArg &OriginalArg : OriginalCallArgs) {
4855 assert((bool)InitList == OriginalArg.DecomposedParam &&
4856 "decomposed non-init-list in auto deduction?");
4858 CheckOriginalCallArgDeduction(*this, Info, OriginalArg, DeducedA)) {
4859 Result = QualType();
4860 return DeductionFailed(TDK, {});
4864 return DAR_Succeeded;
4867 QualType Sema::SubstAutoType(QualType TypeWithAuto,
4868 QualType TypeToReplaceAuto) {
4869 if (TypeToReplaceAuto->isDependentType())
4870 return SubstituteDeducedTypeTransform(
4871 *this, DependentAuto{
4872 TypeToReplaceAuto->containsUnexpandedParameterPack()})
4873 .TransformType(TypeWithAuto);
4874 return SubstituteDeducedTypeTransform(*this, TypeToReplaceAuto)
4875 .TransformType(TypeWithAuto);
4878 TypeSourceInfo *Sema::SubstAutoTypeSourceInfo(TypeSourceInfo *TypeWithAuto,
4879 QualType TypeToReplaceAuto) {
4880 if (TypeToReplaceAuto->isDependentType())
4881 return SubstituteDeducedTypeTransform(
4884 TypeToReplaceAuto->containsUnexpandedParameterPack()})
4885 .TransformType(TypeWithAuto);
4886 return SubstituteDeducedTypeTransform(*this, TypeToReplaceAuto)
4887 .TransformType(TypeWithAuto);
4890 QualType Sema::ReplaceAutoType(QualType TypeWithAuto,
4891 QualType TypeToReplaceAuto) {
4892 return SubstituteDeducedTypeTransform(*this, TypeToReplaceAuto,
4893 /*UseTypeSugar*/ false)
4894 .TransformType(TypeWithAuto);
4897 TypeSourceInfo *Sema::ReplaceAutoTypeSourceInfo(TypeSourceInfo *TypeWithAuto,
4898 QualType TypeToReplaceAuto) {
4899 return SubstituteDeducedTypeTransform(*this, TypeToReplaceAuto,
4900 /*UseTypeSugar*/ false)
4901 .TransformType(TypeWithAuto);
4904 void Sema::DiagnoseAutoDeductionFailure(VarDecl *VDecl, Expr *Init) {
4905 if (isa<InitListExpr>(Init))
4906 Diag(VDecl->getLocation(),
4907 VDecl->isInitCapture()
4908 ? diag::err_init_capture_deduction_failure_from_init_list
4909 : diag::err_auto_var_deduction_failure_from_init_list)
4910 << VDecl->getDeclName() << VDecl->getType() << Init->getSourceRange();
4912 Diag(VDecl->getLocation(),
4913 VDecl->isInitCapture() ? diag::err_init_capture_deduction_failure
4914 : diag::err_auto_var_deduction_failure)
4915 << VDecl->getDeclName() << VDecl->getType() << Init->getType()
4916 << Init->getSourceRange();
4919 bool Sema::DeduceReturnType(FunctionDecl *FD, SourceLocation Loc,
4921 assert(FD->getReturnType()->isUndeducedType());
4923 // For a lambda's conversion operator, deduce any 'auto' or 'decltype(auto)'
4924 // within the return type from the call operator's type.
4925 if (isLambdaConversionOperator(FD)) {
4926 CXXRecordDecl *Lambda = cast<CXXMethodDecl>(FD)->getParent();
4927 FunctionDecl *CallOp = Lambda->getLambdaCallOperator();
4929 // For a generic lambda, instantiate the call operator if needed.
4930 if (auto *Args = FD->getTemplateSpecializationArgs()) {
4931 CallOp = InstantiateFunctionDeclaration(
4932 CallOp->getDescribedFunctionTemplate(), Args, Loc);
4933 if (!CallOp || CallOp->isInvalidDecl())
4936 // We might need to deduce the return type by instantiating the definition
4937 // of the operator() function.
4938 if (CallOp->getReturnType()->isUndeducedType()) {
4939 runWithSufficientStackSpace(Loc, [&] {
4940 InstantiateFunctionDefinition(Loc, CallOp);
4945 if (CallOp->isInvalidDecl())
4947 assert(!CallOp->getReturnType()->isUndeducedType() &&
4948 "failed to deduce lambda return type");
4950 // Build the new return type from scratch.
4951 QualType RetType = getLambdaConversionFunctionResultType(
4952 CallOp->getType()->castAs<FunctionProtoType>());
4953 if (FD->getReturnType()->getAs<PointerType>())
4954 RetType = Context.getPointerType(RetType);
4956 assert(FD->getReturnType()->getAs<BlockPointerType>());
4957 RetType = Context.getBlockPointerType(RetType);
4959 Context.adjustDeducedFunctionResultType(FD, RetType);
4963 if (FD->getTemplateInstantiationPattern()) {
4964 runWithSufficientStackSpace(Loc, [&] {
4965 InstantiateFunctionDefinition(Loc, FD);
4969 bool StillUndeduced = FD->getReturnType()->isUndeducedType();
4970 if (StillUndeduced && Diagnose && !FD->isInvalidDecl()) {
4971 Diag(Loc, diag::err_auto_fn_used_before_defined) << FD;
4972 Diag(FD->getLocation(), diag::note_callee_decl) << FD;
4975 return StillUndeduced;
4978 /// If this is a non-static member function,
4980 AddImplicitObjectParameterType(ASTContext &Context,
4981 CXXMethodDecl *Method,
4982 SmallVectorImpl<QualType> &ArgTypes) {
4983 // C++11 [temp.func.order]p3:
4984 // [...] The new parameter is of type "reference to cv A," where cv are
4985 // the cv-qualifiers of the function template (if any) and A is
4986 // the class of which the function template is a member.
4988 // The standard doesn't say explicitly, but we pick the appropriate kind of
4989 // reference type based on [over.match.funcs]p4.
4990 QualType ArgTy = Context.getTypeDeclType(Method->getParent());
4991 ArgTy = Context.getQualifiedType(ArgTy, Method->getMethodQualifiers());
4992 if (Method->getRefQualifier() == RQ_RValue)
4993 ArgTy = Context.getRValueReferenceType(ArgTy);
4995 ArgTy = Context.getLValueReferenceType(ArgTy);
4996 ArgTypes.push_back(ArgTy);
4999 /// Determine whether the function template \p FT1 is at least as
5000 /// specialized as \p FT2.
5001 static bool isAtLeastAsSpecializedAs(Sema &S,
5003 FunctionTemplateDecl *FT1,
5004 FunctionTemplateDecl *FT2,
5005 TemplatePartialOrderingContext TPOC,
5006 unsigned NumCallArguments1,
5008 assert(!Reversed || TPOC == TPOC_Call);
5010 FunctionDecl *FD1 = FT1->getTemplatedDecl();
5011 FunctionDecl *FD2 = FT2->getTemplatedDecl();
5012 const FunctionProtoType *Proto1 = FD1->getType()->getAs<FunctionProtoType>();
5013 const FunctionProtoType *Proto2 = FD2->getType()->getAs<FunctionProtoType>();
5015 assert(Proto1 && Proto2 && "Function templates must have prototypes");
5016 TemplateParameterList *TemplateParams = FT2->getTemplateParameters();
5017 SmallVector<DeducedTemplateArgument, 4> Deduced;
5018 Deduced.resize(TemplateParams->size());
5020 // C++0x [temp.deduct.partial]p3:
5021 // The types used to determine the ordering depend on the context in which
5022 // the partial ordering is done:
5023 TemplateDeductionInfo Info(Loc);
5024 SmallVector<QualType, 4> Args2;
5027 // - In the context of a function call, the function parameter types are
5029 CXXMethodDecl *Method1 = dyn_cast<CXXMethodDecl>(FD1);
5030 CXXMethodDecl *Method2 = dyn_cast<CXXMethodDecl>(FD2);
5032 // C++11 [temp.func.order]p3:
5033 // [...] If only one of the function templates is a non-static
5034 // member, that function template is considered to have a new
5035 // first parameter inserted in its function parameter list. The
5036 // new parameter is of type "reference to cv A," where cv are
5037 // the cv-qualifiers of the function template (if any) and A is
5038 // the class of which the function template is a member.
5040 // Note that we interpret this to mean "if one of the function
5041 // templates is a non-static member and the other is a non-member";
5042 // otherwise, the ordering rules for static functions against non-static
5043 // functions don't make any sense.
5045 // C++98/03 doesn't have this provision but we've extended DR532 to cover
5046 // it as wording was broken prior to it.
5047 SmallVector<QualType, 4> Args1;
5049 unsigned NumComparedArguments = NumCallArguments1;
5051 if (!Method2 && Method1 && !Method1->isStatic()) {
5052 // Compare 'this' from Method1 against first parameter from Method2.
5053 AddImplicitObjectParameterType(S.Context, Method1, Args1);
5054 ++NumComparedArguments;
5055 } else if (!Method1 && Method2 && !Method2->isStatic()) {
5056 // Compare 'this' from Method2 against first parameter from Method1.
5057 AddImplicitObjectParameterType(S.Context, Method2, Args2);
5058 } else if (Method1 && Method2 && Reversed) {
5059 // Compare 'this' from Method1 against second parameter from Method2
5060 // and 'this' from Method2 against second parameter from Method1.
5061 AddImplicitObjectParameterType(S.Context, Method1, Args1);
5062 AddImplicitObjectParameterType(S.Context, Method2, Args2);
5063 ++NumComparedArguments;
5066 Args1.insert(Args1.end(), Proto1->param_type_begin(),
5067 Proto1->param_type_end());
5068 Args2.insert(Args2.end(), Proto2->param_type_begin(),
5069 Proto2->param_type_end());
5071 // C++ [temp.func.order]p5:
5072 // The presence of unused ellipsis and default arguments has no effect on
5073 // the partial ordering of function templates.
5074 if (Args1.size() > NumComparedArguments)
5075 Args1.resize(NumComparedArguments);
5076 if (Args2.size() > NumComparedArguments)
5077 Args2.resize(NumComparedArguments);
5079 std::reverse(Args2.begin(), Args2.end());
5080 if (DeduceTemplateArguments(S, TemplateParams, Args2.data(), Args2.size(),
5081 Args1.data(), Args1.size(), Info, Deduced,
5082 TDF_None, /*PartialOrdering=*/true))
5088 case TPOC_Conversion:
5089 // - In the context of a call to a conversion operator, the return types
5090 // of the conversion function templates are used.
5091 if (DeduceTemplateArgumentsByTypeMatch(
5092 S, TemplateParams, Proto2->getReturnType(), Proto1->getReturnType(),
5093 Info, Deduced, TDF_None,
5094 /*PartialOrdering=*/true))
5099 // - In other contexts (14.6.6.2) the function template's function type
5101 if (DeduceTemplateArgumentsByTypeMatch(S, TemplateParams,
5102 FD2->getType(), FD1->getType(),
5103 Info, Deduced, TDF_None,
5104 /*PartialOrdering=*/true))
5109 // C++0x [temp.deduct.partial]p11:
5110 // In most cases, all template parameters must have values in order for
5111 // deduction to succeed, but for partial ordering purposes a template
5112 // parameter may remain without a value provided it is not used in the
5113 // types being used for partial ordering. [ Note: a template parameter used
5114 // in a non-deduced context is considered used. -end note]
5115 unsigned ArgIdx = 0, NumArgs = Deduced.size();
5116 for (; ArgIdx != NumArgs; ++ArgIdx)
5117 if (Deduced[ArgIdx].isNull())
5120 // FIXME: We fail to implement [temp.deduct.type]p1 along this path. We need
5121 // to substitute the deduced arguments back into the template and check that
5122 // we get the right type.
5124 if (ArgIdx == NumArgs) {
5125 // All template arguments were deduced. FT1 is at least as specialized
5130 // Figure out which template parameters were used.
5131 llvm::SmallBitVector UsedParameters(TemplateParams->size());
5134 for (unsigned I = 0, N = Args2.size(); I != N; ++I)
5135 ::MarkUsedTemplateParameters(S.Context, Args2[I], false,
5136 TemplateParams->getDepth(),
5140 case TPOC_Conversion:
5141 ::MarkUsedTemplateParameters(S.Context, Proto2->getReturnType(), false,
5142 TemplateParams->getDepth(), UsedParameters);
5146 ::MarkUsedTemplateParameters(S.Context, FD2->getType(), false,
5147 TemplateParams->getDepth(),
5152 for (; ArgIdx != NumArgs; ++ArgIdx)
5153 // If this argument had no value deduced but was used in one of the types
5154 // used for partial ordering, then deduction fails.
5155 if (Deduced[ArgIdx].isNull() && UsedParameters[ArgIdx])
5161 /// Determine whether this a function template whose parameter-type-list
5162 /// ends with a function parameter pack.
5163 static bool isVariadicFunctionTemplate(FunctionTemplateDecl *FunTmpl) {
5164 FunctionDecl *Function = FunTmpl->getTemplatedDecl();
5165 unsigned NumParams = Function->getNumParams();
5169 ParmVarDecl *Last = Function->getParamDecl(NumParams - 1);
5170 if (!Last->isParameterPack())
5173 // Make sure that no previous parameter is a parameter pack.
5174 while (--NumParams > 0) {
5175 if (Function->getParamDecl(NumParams - 1)->isParameterPack())
5182 /// Returns the more specialized function template according
5183 /// to the rules of function template partial ordering (C++ [temp.func.order]).
5185 /// \param FT1 the first function template
5187 /// \param FT2 the second function template
5189 /// \param TPOC the context in which we are performing partial ordering of
5190 /// function templates.
5192 /// \param NumCallArguments1 The number of arguments in the call to FT1, used
5193 /// only when \c TPOC is \c TPOC_Call.
5195 /// \param NumCallArguments2 The number of arguments in the call to FT2, used
5196 /// only when \c TPOC is \c TPOC_Call.
5198 /// \param Reversed If \c true, exactly one of FT1 and FT2 is an overload
5199 /// candidate with a reversed parameter order. In this case, the corresponding
5200 /// P/A pairs between FT1 and FT2 are reversed.
5202 /// \returns the more specialized function template. If neither
5203 /// template is more specialized, returns NULL.
5204 FunctionTemplateDecl *
5205 Sema::getMoreSpecializedTemplate(FunctionTemplateDecl *FT1,
5206 FunctionTemplateDecl *FT2,
5208 TemplatePartialOrderingContext TPOC,
5209 unsigned NumCallArguments1,
5210 unsigned NumCallArguments2,
5213 auto JudgeByConstraints = [&] () -> FunctionTemplateDecl * {
5214 llvm::SmallVector<const Expr *, 3> AC1, AC2;
5215 FT1->getAssociatedConstraints(AC1);
5216 FT2->getAssociatedConstraints(AC2);
5217 bool AtLeastAsConstrained1, AtLeastAsConstrained2;
5218 if (IsAtLeastAsConstrained(FT1, AC1, FT2, AC2, AtLeastAsConstrained1))
5220 if (IsAtLeastAsConstrained(FT2, AC2, FT1, AC1, AtLeastAsConstrained2))
5222 if (AtLeastAsConstrained1 == AtLeastAsConstrained2)
5224 return AtLeastAsConstrained1 ? FT1 : FT2;
5227 bool Better1 = isAtLeastAsSpecializedAs(*this, Loc, FT1, FT2, TPOC,
5228 NumCallArguments1, Reversed);
5229 bool Better2 = isAtLeastAsSpecializedAs(*this, Loc, FT2, FT1, TPOC,
5230 NumCallArguments2, Reversed);
5232 if (Better1 != Better2) // We have a clear winner
5233 return Better1 ? FT1 : FT2;
5235 if (!Better1 && !Better2) // Neither is better than the other
5236 return JudgeByConstraints();
5238 // FIXME: This mimics what GCC implements, but doesn't match up with the
5239 // proposed resolution for core issue 692. This area needs to be sorted out,
5240 // but for now we attempt to maintain compatibility.
5241 bool Variadic1 = isVariadicFunctionTemplate(FT1);
5242 bool Variadic2 = isVariadicFunctionTemplate(FT2);
5243 if (Variadic1 != Variadic2)
5244 return Variadic1? FT2 : FT1;
5246 return JudgeByConstraints();
5249 /// Determine if the two templates are equivalent.
5250 static bool isSameTemplate(TemplateDecl *T1, TemplateDecl *T2) {
5257 return T1->getCanonicalDecl() == T2->getCanonicalDecl();
5260 /// Retrieve the most specialized of the given function template
5261 /// specializations.
5263 /// \param SpecBegin the start iterator of the function template
5264 /// specializations that we will be comparing.
5266 /// \param SpecEnd the end iterator of the function template
5267 /// specializations, paired with \p SpecBegin.
5269 /// \param Loc the location where the ambiguity or no-specializations
5270 /// diagnostic should occur.
5272 /// \param NoneDiag partial diagnostic used to diagnose cases where there are
5273 /// no matching candidates.
5275 /// \param AmbigDiag partial diagnostic used to diagnose an ambiguity, if one
5278 /// \param CandidateDiag partial diagnostic used for each function template
5279 /// specialization that is a candidate in the ambiguous ordering. One parameter
5280 /// in this diagnostic should be unbound, which will correspond to the string
5281 /// describing the template arguments for the function template specialization.
5283 /// \returns the most specialized function template specialization, if
5284 /// found. Otherwise, returns SpecEnd.
5285 UnresolvedSetIterator Sema::getMostSpecialized(
5286 UnresolvedSetIterator SpecBegin, UnresolvedSetIterator SpecEnd,
5287 TemplateSpecCandidateSet &FailedCandidates,
5288 SourceLocation Loc, const PartialDiagnostic &NoneDiag,
5289 const PartialDiagnostic &AmbigDiag, const PartialDiagnostic &CandidateDiag,
5290 bool Complain, QualType TargetType) {
5291 if (SpecBegin == SpecEnd) {
5293 Diag(Loc, NoneDiag);
5294 FailedCandidates.NoteCandidates(*this, Loc);
5299 if (SpecBegin + 1 == SpecEnd)
5302 // Find the function template that is better than all of the templates it
5303 // has been compared to.
5304 UnresolvedSetIterator Best = SpecBegin;
5305 FunctionTemplateDecl *BestTemplate
5306 = cast<FunctionDecl>(*Best)->getPrimaryTemplate();
5307 assert(BestTemplate && "Not a function template specialization?");
5308 for (UnresolvedSetIterator I = SpecBegin + 1; I != SpecEnd; ++I) {
5309 FunctionTemplateDecl *Challenger
5310 = cast<FunctionDecl>(*I)->getPrimaryTemplate();
5311 assert(Challenger && "Not a function template specialization?");
5312 if (isSameTemplate(getMoreSpecializedTemplate(BestTemplate, Challenger,
5313 Loc, TPOC_Other, 0, 0),
5316 BestTemplate = Challenger;
5320 // Make sure that the "best" function template is more specialized than all
5322 bool Ambiguous = false;
5323 for (UnresolvedSetIterator I = SpecBegin; I != SpecEnd; ++I) {
5324 FunctionTemplateDecl *Challenger
5325 = cast<FunctionDecl>(*I)->getPrimaryTemplate();
5327 !isSameTemplate(getMoreSpecializedTemplate(BestTemplate, Challenger,
5328 Loc, TPOC_Other, 0, 0),
5336 // We found an answer. Return it.
5340 // Diagnose the ambiguity.
5342 Diag(Loc, AmbigDiag);
5344 // FIXME: Can we order the candidates in some sane way?
5345 for (UnresolvedSetIterator I = SpecBegin; I != SpecEnd; ++I) {
5346 PartialDiagnostic PD = CandidateDiag;
5347 const auto *FD = cast<FunctionDecl>(*I);
5348 PD << FD << getTemplateArgumentBindingsText(
5349 FD->getPrimaryTemplate()->getTemplateParameters(),
5350 *FD->getTemplateSpecializationArgs());
5351 if (!TargetType.isNull())
5352 HandleFunctionTypeMismatch(PD, FD->getType(), TargetType);
5353 Diag((*I)->getLocation(), PD);
5360 /// Determine whether one partial specialization, P1, is at least as
5361 /// specialized than another, P2.
5363 /// \tparam TemplateLikeDecl The kind of P2, which must be a
5364 /// TemplateDecl or {Class,Var}TemplatePartialSpecializationDecl.
5365 /// \param T1 The injected-class-name of P1 (faked for a variable template).
5366 /// \param T2 The injected-class-name of P2 (faked for a variable template).
5367 template<typename TemplateLikeDecl>
5368 static bool isAtLeastAsSpecializedAs(Sema &S, QualType T1, QualType T2,
5369 TemplateLikeDecl *P2,
5370 TemplateDeductionInfo &Info) {
5371 // C++ [temp.class.order]p1:
5372 // For two class template partial specializations, the first is at least as
5373 // specialized as the second if, given the following rewrite to two
5374 // function templates, the first function template is at least as
5375 // specialized as the second according to the ordering rules for function
5376 // templates (14.6.6.2):
5377 // - the first function template has the same template parameters as the
5378 // first partial specialization and has a single function parameter
5379 // whose type is a class template specialization with the template
5380 // arguments of the first partial specialization, and
5381 // - the second function template has the same template parameters as the
5382 // second partial specialization and has a single function parameter
5383 // whose type is a class template specialization with the template
5384 // arguments of the second partial specialization.
5386 // Rather than synthesize function templates, we merely perform the
5387 // equivalent partial ordering by performing deduction directly on
5388 // the template arguments of the class template partial
5389 // specializations. This computation is slightly simpler than the
5390 // general problem of function template partial ordering, because
5391 // class template partial specializations are more constrained. We
5392 // know that every template parameter is deducible from the class
5393 // template partial specialization's template arguments, for
5395 SmallVector<DeducedTemplateArgument, 4> Deduced;
5397 // Determine whether P1 is at least as specialized as P2.
5398 Deduced.resize(P2->getTemplateParameters()->size());
5399 if (DeduceTemplateArgumentsByTypeMatch(S, P2->getTemplateParameters(),
5400 T2, T1, Info, Deduced, TDF_None,
5401 /*PartialOrdering=*/true))
5404 SmallVector<TemplateArgument, 4> DeducedArgs(Deduced.begin(),
5406 Sema::InstantiatingTemplate Inst(S, Info.getLocation(), P2, DeducedArgs,
5408 auto *TST1 = T1->castAs<TemplateSpecializationType>();
5409 bool AtLeastAsSpecialized;
5410 S.runWithSufficientStackSpace(Info.getLocation(), [&] {
5411 AtLeastAsSpecialized = !FinishTemplateArgumentDeduction(
5412 S, P2, /*IsPartialOrdering=*/true,
5413 TemplateArgumentList(TemplateArgumentList::OnStack,
5414 TST1->template_arguments()),
5417 return AtLeastAsSpecialized;
5420 /// Returns the more specialized class template partial specialization
5421 /// according to the rules of partial ordering of class template partial
5422 /// specializations (C++ [temp.class.order]).
5424 /// \param PS1 the first class template partial specialization
5426 /// \param PS2 the second class template partial specialization
5428 /// \returns the more specialized class template partial specialization. If
5429 /// neither partial specialization is more specialized, returns NULL.
5430 ClassTemplatePartialSpecializationDecl *
5431 Sema::getMoreSpecializedPartialSpecialization(
5432 ClassTemplatePartialSpecializationDecl *PS1,
5433 ClassTemplatePartialSpecializationDecl *PS2,
5434 SourceLocation Loc) {
5435 QualType PT1 = PS1->getInjectedSpecializationType();
5436 QualType PT2 = PS2->getInjectedSpecializationType();
5438 TemplateDeductionInfo Info(Loc);
5439 bool Better1 = isAtLeastAsSpecializedAs(*this, PT1, PT2, PS2, Info);
5440 bool Better2 = isAtLeastAsSpecializedAs(*this, PT2, PT1, PS1, Info);
5442 if (!Better1 && !Better2)
5444 if (Better1 && Better2) {
5445 llvm::SmallVector<const Expr *, 3> AC1, AC2;
5446 PS1->getAssociatedConstraints(AC1);
5447 PS2->getAssociatedConstraints(AC2);
5448 bool AtLeastAsConstrained1, AtLeastAsConstrained2;
5449 if (IsAtLeastAsConstrained(PS1, AC1, PS2, AC2, AtLeastAsConstrained1))
5451 if (IsAtLeastAsConstrained(PS2, AC2, PS1, AC1, AtLeastAsConstrained2))
5453 if (AtLeastAsConstrained1 == AtLeastAsConstrained2)
5455 return AtLeastAsConstrained1 ? PS1 : PS2;
5458 return Better1 ? PS1 : PS2;
5461 bool Sema::isMoreSpecializedThanPrimary(
5462 ClassTemplatePartialSpecializationDecl *Spec, TemplateDeductionInfo &Info) {
5463 ClassTemplateDecl *Primary = Spec->getSpecializedTemplate();
5464 QualType PrimaryT = Primary->getInjectedClassNameSpecialization();
5465 QualType PartialT = Spec->getInjectedSpecializationType();
5466 if (!isAtLeastAsSpecializedAs(*this, PartialT, PrimaryT, Primary, Info))
5468 if (!isAtLeastAsSpecializedAs(*this, PrimaryT, PartialT, Spec, Info))
5470 Info.clearSFINAEDiagnostic();
5471 llvm::SmallVector<const Expr *, 3> PrimaryAC, SpecAC;
5472 Primary->getAssociatedConstraints(PrimaryAC);
5473 Spec->getAssociatedConstraints(SpecAC);
5474 bool AtLeastAsConstrainedPrimary, AtLeastAsConstrainedSpec;
5475 if (IsAtLeastAsConstrained(Spec, SpecAC, Primary, PrimaryAC,
5476 AtLeastAsConstrainedSpec))
5478 if (!AtLeastAsConstrainedSpec)
5480 if (IsAtLeastAsConstrained(Primary, PrimaryAC, Spec, SpecAC,
5481 AtLeastAsConstrainedPrimary))
5483 return !AtLeastAsConstrainedPrimary;
5486 VarTemplatePartialSpecializationDecl *
5487 Sema::getMoreSpecializedPartialSpecialization(
5488 VarTemplatePartialSpecializationDecl *PS1,
5489 VarTemplatePartialSpecializationDecl *PS2, SourceLocation Loc) {
5490 // Pretend the variable template specializations are class template
5491 // specializations and form a fake injected class name type for comparison.
5492 assert(PS1->getSpecializedTemplate() == PS2->getSpecializedTemplate() &&
5493 "the partial specializations being compared should specialize"
5494 " the same template.");
5495 TemplateName Name(PS1->getSpecializedTemplate());
5496 TemplateName CanonTemplate = Context.getCanonicalTemplateName(Name);
5497 QualType PT1 = Context.getTemplateSpecializationType(
5498 CanonTemplate, PS1->getTemplateArgs().asArray());
5499 QualType PT2 = Context.getTemplateSpecializationType(
5500 CanonTemplate, PS2->getTemplateArgs().asArray());
5502 TemplateDeductionInfo Info(Loc);
5503 bool Better1 = isAtLeastAsSpecializedAs(*this, PT1, PT2, PS2, Info);
5504 bool Better2 = isAtLeastAsSpecializedAs(*this, PT2, PT1, PS1, Info);
5506 if (!Better1 && !Better2)
5508 if (Better1 && Better2) {
5509 llvm::SmallVector<const Expr *, 3> AC1, AC2;
5510 PS1->getAssociatedConstraints(AC1);
5511 PS2->getAssociatedConstraints(AC2);
5512 bool AtLeastAsConstrained1, AtLeastAsConstrained2;
5513 if (IsAtLeastAsConstrained(PS1, AC1, PS2, AC2, AtLeastAsConstrained1))
5515 if (IsAtLeastAsConstrained(PS2, AC2, PS1, AC1, AtLeastAsConstrained2))
5517 if (AtLeastAsConstrained1 == AtLeastAsConstrained2)
5519 return AtLeastAsConstrained1 ? PS1 : PS2;
5522 return Better1 ? PS1 : PS2;
5525 bool Sema::isMoreSpecializedThanPrimary(
5526 VarTemplatePartialSpecializationDecl *Spec, TemplateDeductionInfo &Info) {
5527 TemplateDecl *Primary = Spec->getSpecializedTemplate();
5528 // FIXME: Cache the injected template arguments rather than recomputing
5529 // them for each partial specialization.
5530 SmallVector<TemplateArgument, 8> PrimaryArgs;
5531 Context.getInjectedTemplateArgs(Primary->getTemplateParameters(),
5534 TemplateName CanonTemplate =
5535 Context.getCanonicalTemplateName(TemplateName(Primary));
5536 QualType PrimaryT = Context.getTemplateSpecializationType(
5537 CanonTemplate, PrimaryArgs);
5538 QualType PartialT = Context.getTemplateSpecializationType(
5539 CanonTemplate, Spec->getTemplateArgs().asArray());
5541 if (!isAtLeastAsSpecializedAs(*this, PartialT, PrimaryT, Primary, Info))
5543 if (!isAtLeastAsSpecializedAs(*this, PrimaryT, PartialT, Spec, Info))
5545 Info.clearSFINAEDiagnostic();
5546 llvm::SmallVector<const Expr *, 3> PrimaryAC, SpecAC;
5547 Primary->getAssociatedConstraints(PrimaryAC);
5548 Spec->getAssociatedConstraints(SpecAC);
5549 bool AtLeastAsConstrainedPrimary, AtLeastAsConstrainedSpec;
5550 if (IsAtLeastAsConstrained(Spec, SpecAC, Primary, PrimaryAC,
5551 AtLeastAsConstrainedSpec))
5553 if (!AtLeastAsConstrainedSpec)
5555 if (IsAtLeastAsConstrained(Primary, PrimaryAC, Spec, SpecAC,
5556 AtLeastAsConstrainedPrimary))
5558 return !AtLeastAsConstrainedPrimary;
5561 bool Sema::isTemplateTemplateParameterAtLeastAsSpecializedAs(
5562 TemplateParameterList *P, TemplateDecl *AArg, SourceLocation Loc) {
5563 // C++1z [temp.arg.template]p4: (DR 150)
5564 // A template template-parameter P is at least as specialized as a
5565 // template template-argument A if, given the following rewrite to two
5566 // function templates...
5568 // Rather than synthesize function templates, we merely perform the
5569 // equivalent partial ordering by performing deduction directly on
5570 // the template parameter lists of the template template parameters.
5572 // Given an invented class template X with the template parameter list of
5573 // A (including default arguments):
5574 TemplateName X = Context.getCanonicalTemplateName(TemplateName(AArg));
5575 TemplateParameterList *A = AArg->getTemplateParameters();
5577 // - Each function template has a single function parameter whose type is
5578 // a specialization of X with template arguments corresponding to the
5579 // template parameters from the respective function template
5580 SmallVector<TemplateArgument, 8> AArgs;
5581 Context.getInjectedTemplateArgs(A, AArgs);
5583 // Check P's arguments against A's parameter list. This will fill in default
5584 // template arguments as needed. AArgs are already correct by construction.
5585 // We can't just use CheckTemplateIdType because that will expand alias
5587 SmallVector<TemplateArgument, 4> PArgs;
5589 SFINAETrap Trap(*this);
5591 Context.getInjectedTemplateArgs(P, PArgs);
5592 TemplateArgumentListInfo PArgList(P->getLAngleLoc(),
5594 for (unsigned I = 0, N = P->size(); I != N; ++I) {
5595 // Unwrap packs that getInjectedTemplateArgs wrapped around pack
5596 // expansions, to form an "as written" argument list.
5597 TemplateArgument Arg = PArgs[I];
5598 if (Arg.getKind() == TemplateArgument::Pack) {
5599 assert(Arg.pack_size() == 1 && Arg.pack_begin()->isPackExpansion());
5600 Arg = *Arg.pack_begin();
5602 PArgList.addArgument(getTrivialTemplateArgumentLoc(
5603 Arg, QualType(), P->getParam(I)->getLocation()));
5607 // C++1z [temp.arg.template]p3:
5608 // If the rewrite produces an invalid type, then P is not at least as
5609 // specialized as A.
5610 if (CheckTemplateArgumentList(AArg, Loc, PArgList, false, PArgs) ||
5611 Trap.hasErrorOccurred())
5615 QualType AType = Context.getTemplateSpecializationType(X, AArgs);
5616 QualType PType = Context.getTemplateSpecializationType(X, PArgs);
5618 // ... the function template corresponding to P is at least as specialized
5619 // as the function template corresponding to A according to the partial
5620 // ordering rules for function templates.
5621 TemplateDeductionInfo Info(Loc, A->getDepth());
5622 return isAtLeastAsSpecializedAs(*this, PType, AType, AArg, Info);
5626 struct MarkUsedTemplateParameterVisitor :
5627 RecursiveASTVisitor<MarkUsedTemplateParameterVisitor> {
5628 llvm::SmallBitVector &Used;
5631 MarkUsedTemplateParameterVisitor(llvm::SmallBitVector &Used,
5633 : Used(Used), Depth(Depth) { }
5635 bool VisitTemplateTypeParmType(TemplateTypeParmType *T) {
5636 if (T->getDepth() == Depth)
5637 Used[T->getIndex()] = true;
5641 bool TraverseTemplateName(TemplateName Template) {
5643 dyn_cast<TemplateTemplateParmDecl>(Template.getAsTemplateDecl()))
5644 if (TTP->getDepth() == Depth)
5645 Used[TTP->getIndex()] = true;
5646 RecursiveASTVisitor<MarkUsedTemplateParameterVisitor>::
5647 TraverseTemplateName(Template);
5651 bool VisitDeclRefExpr(DeclRefExpr *E) {
5652 if (auto *NTTP = dyn_cast<NonTypeTemplateParmDecl>(E->getDecl()))
5653 if (NTTP->getDepth() == Depth)
5654 Used[NTTP->getIndex()] = true;
5660 /// Mark the template parameters that are used by the given
5663 MarkUsedTemplateParameters(ASTContext &Ctx,
5667 llvm::SmallBitVector &Used) {
5669 MarkUsedTemplateParameterVisitor(Used, Depth)
5670 .TraverseStmt(const_cast<Expr *>(E));
5674 // We can deduce from a pack expansion.
5675 if (const PackExpansionExpr *Expansion = dyn_cast<PackExpansionExpr>(E))
5676 E = Expansion->getPattern();
5678 // Skip through any implicit casts we added while type-checking, and any
5679 // substitutions performed by template alias expansion.
5681 if (const ImplicitCastExpr *ICE = dyn_cast<ImplicitCastExpr>(E))
5682 E = ICE->getSubExpr();
5683 else if (const ConstantExpr *CE = dyn_cast<ConstantExpr>(E))
5684 E = CE->getSubExpr();
5685 else if (const SubstNonTypeTemplateParmExpr *Subst =
5686 dyn_cast<SubstNonTypeTemplateParmExpr>(E))
5687 E = Subst->getReplacement();
5692 const DeclRefExpr *DRE = dyn_cast<DeclRefExpr>(E);
5696 const NonTypeTemplateParmDecl *NTTP
5697 = dyn_cast<NonTypeTemplateParmDecl>(DRE->getDecl());
5701 if (NTTP->getDepth() == Depth)
5702 Used[NTTP->getIndex()] = true;
5704 // In C++17 mode, additional arguments may be deduced from the type of a
5705 // non-type argument.
5706 if (Ctx.getLangOpts().CPlusPlus17)
5707 MarkUsedTemplateParameters(Ctx, NTTP->getType(), OnlyDeduced, Depth, Used);
5710 /// Mark the template parameters that are used by the given
5711 /// nested name specifier.
5713 MarkUsedTemplateParameters(ASTContext &Ctx,
5714 NestedNameSpecifier *NNS,
5717 llvm::SmallBitVector &Used) {
5721 MarkUsedTemplateParameters(Ctx, NNS->getPrefix(), OnlyDeduced, Depth,
5723 MarkUsedTemplateParameters(Ctx, QualType(NNS->getAsType(), 0),
5724 OnlyDeduced, Depth, Used);
5727 /// Mark the template parameters that are used by the given
5730 MarkUsedTemplateParameters(ASTContext &Ctx,
5734 llvm::SmallBitVector &Used) {
5735 if (TemplateDecl *Template = Name.getAsTemplateDecl()) {
5736 if (TemplateTemplateParmDecl *TTP
5737 = dyn_cast<TemplateTemplateParmDecl>(Template)) {
5738 if (TTP->getDepth() == Depth)
5739 Used[TTP->getIndex()] = true;
5744 if (QualifiedTemplateName *QTN = Name.getAsQualifiedTemplateName())
5745 MarkUsedTemplateParameters(Ctx, QTN->getQualifier(), OnlyDeduced,
5747 if (DependentTemplateName *DTN = Name.getAsDependentTemplateName())
5748 MarkUsedTemplateParameters(Ctx, DTN->getQualifier(), OnlyDeduced,
5752 /// Mark the template parameters that are used by the given
5755 MarkUsedTemplateParameters(ASTContext &Ctx, QualType T,
5758 llvm::SmallBitVector &Used) {
5762 // Non-dependent types have nothing deducible
5763 if (!T->isDependentType())
5766 T = Ctx.getCanonicalType(T);
5767 switch (T->getTypeClass()) {
5769 MarkUsedTemplateParameters(Ctx,
5770 cast<PointerType>(T)->getPointeeType(),
5776 case Type::BlockPointer:
5777 MarkUsedTemplateParameters(Ctx,
5778 cast<BlockPointerType>(T)->getPointeeType(),
5784 case Type::LValueReference:
5785 case Type::RValueReference:
5786 MarkUsedTemplateParameters(Ctx,
5787 cast<ReferenceType>(T)->getPointeeType(),
5793 case Type::MemberPointer: {
5794 const MemberPointerType *MemPtr = cast<MemberPointerType>(T.getTypePtr());
5795 MarkUsedTemplateParameters(Ctx, MemPtr->getPointeeType(), OnlyDeduced,
5797 MarkUsedTemplateParameters(Ctx, QualType(MemPtr->getClass(), 0),
5798 OnlyDeduced, Depth, Used);
5802 case Type::DependentSizedArray:
5803 MarkUsedTemplateParameters(Ctx,
5804 cast<DependentSizedArrayType>(T)->getSizeExpr(),
5805 OnlyDeduced, Depth, Used);
5806 // Fall through to check the element type
5809 case Type::ConstantArray:
5810 case Type::IncompleteArray:
5811 MarkUsedTemplateParameters(Ctx,
5812 cast<ArrayType>(T)->getElementType(),
5813 OnlyDeduced, Depth, Used);
5817 case Type::ExtVector:
5818 MarkUsedTemplateParameters(Ctx,
5819 cast<VectorType>(T)->getElementType(),
5820 OnlyDeduced, Depth, Used);
5823 case Type::DependentVector: {
5824 const auto *VecType = cast<DependentVectorType>(T);
5825 MarkUsedTemplateParameters(Ctx, VecType->getElementType(), OnlyDeduced,
5827 MarkUsedTemplateParameters(Ctx, VecType->getSizeExpr(), OnlyDeduced, Depth,
5831 case Type::DependentSizedExtVector: {
5832 const DependentSizedExtVectorType *VecType
5833 = cast<DependentSizedExtVectorType>(T);
5834 MarkUsedTemplateParameters(Ctx, VecType->getElementType(), OnlyDeduced,
5836 MarkUsedTemplateParameters(Ctx, VecType->getSizeExpr(), OnlyDeduced,
5841 case Type::DependentAddressSpace: {
5842 const DependentAddressSpaceType *DependentASType =
5843 cast<DependentAddressSpaceType>(T);
5844 MarkUsedTemplateParameters(Ctx, DependentASType->getPointeeType(),
5845 OnlyDeduced, Depth, Used);
5846 MarkUsedTemplateParameters(Ctx,
5847 DependentASType->getAddrSpaceExpr(),
5848 OnlyDeduced, Depth, Used);
5852 case Type::ConstantMatrix: {
5853 const ConstantMatrixType *MatType = cast<ConstantMatrixType>(T);
5854 MarkUsedTemplateParameters(Ctx, MatType->getElementType(), OnlyDeduced,
5859 case Type::DependentSizedMatrix: {
5860 const DependentSizedMatrixType *MatType = cast<DependentSizedMatrixType>(T);
5861 MarkUsedTemplateParameters(Ctx, MatType->getElementType(), OnlyDeduced,
5863 MarkUsedTemplateParameters(Ctx, MatType->getRowExpr(), OnlyDeduced, Depth,
5865 MarkUsedTemplateParameters(Ctx, MatType->getColumnExpr(), OnlyDeduced,
5870 case Type::FunctionProto: {
5871 const FunctionProtoType *Proto = cast<FunctionProtoType>(T);
5872 MarkUsedTemplateParameters(Ctx, Proto->getReturnType(), OnlyDeduced, Depth,
5874 for (unsigned I = 0, N = Proto->getNumParams(); I != N; ++I) {
5875 // C++17 [temp.deduct.type]p5:
5876 // The non-deduced contexts are: [...]
5877 // -- A function parameter pack that does not occur at the end of the
5878 // parameter-declaration-list.
5879 if (!OnlyDeduced || I + 1 == N ||
5880 !Proto->getParamType(I)->getAs<PackExpansionType>()) {
5881 MarkUsedTemplateParameters(Ctx, Proto->getParamType(I), OnlyDeduced,
5884 // FIXME: C++17 [temp.deduct.call]p1:
5885 // When a function parameter pack appears in a non-deduced context,
5886 // the type of that pack is never deduced.
5888 // We should also track a set of "never deduced" parameters, and
5889 // subtract that from the list of deduced parameters after marking.
5892 if (auto *E = Proto->getNoexceptExpr())
5893 MarkUsedTemplateParameters(Ctx, E, OnlyDeduced, Depth, Used);
5897 case Type::TemplateTypeParm: {
5898 const TemplateTypeParmType *TTP = cast<TemplateTypeParmType>(T);
5899 if (TTP->getDepth() == Depth)
5900 Used[TTP->getIndex()] = true;
5904 case Type::SubstTemplateTypeParmPack: {
5905 const SubstTemplateTypeParmPackType *Subst
5906 = cast<SubstTemplateTypeParmPackType>(T);
5907 MarkUsedTemplateParameters(Ctx,
5908 QualType(Subst->getReplacedParameter(), 0),
5909 OnlyDeduced, Depth, Used);
5910 MarkUsedTemplateParameters(Ctx, Subst->getArgumentPack(),
5911 OnlyDeduced, Depth, Used);
5915 case Type::InjectedClassName:
5916 T = cast<InjectedClassNameType>(T)->getInjectedSpecializationType();
5919 case Type::TemplateSpecialization: {
5920 const TemplateSpecializationType *Spec
5921 = cast<TemplateSpecializationType>(T);
5922 MarkUsedTemplateParameters(Ctx, Spec->getTemplateName(), OnlyDeduced,
5925 // C++0x [temp.deduct.type]p9:
5926 // If the template argument list of P contains a pack expansion that is
5927 // not the last template argument, the entire template argument list is a
5928 // non-deduced context.
5930 hasPackExpansionBeforeEnd(Spec->template_arguments()))
5933 for (unsigned I = 0, N = Spec->getNumArgs(); I != N; ++I)
5934 MarkUsedTemplateParameters(Ctx, Spec->getArg(I), OnlyDeduced, Depth,
5941 MarkUsedTemplateParameters(Ctx,
5942 cast<ComplexType>(T)->getElementType(),
5943 OnlyDeduced, Depth, Used);
5948 MarkUsedTemplateParameters(Ctx,
5949 cast<AtomicType>(T)->getValueType(),
5950 OnlyDeduced, Depth, Used);
5953 case Type::DependentName:
5955 MarkUsedTemplateParameters(Ctx,
5956 cast<DependentNameType>(T)->getQualifier(),
5957 OnlyDeduced, Depth, Used);
5960 case Type::DependentTemplateSpecialization: {
5961 // C++14 [temp.deduct.type]p5:
5962 // The non-deduced contexts are:
5963 // -- The nested-name-specifier of a type that was specified using a
5966 // C++14 [temp.deduct.type]p6:
5967 // When a type name is specified in a way that includes a non-deduced
5968 // context, all of the types that comprise that type name are also
5973 const DependentTemplateSpecializationType *Spec
5974 = cast<DependentTemplateSpecializationType>(T);
5976 MarkUsedTemplateParameters(Ctx, Spec->getQualifier(),
5977 OnlyDeduced, Depth, Used);
5979 for (unsigned I = 0, N = Spec->getNumArgs(); I != N; ++I)
5980 MarkUsedTemplateParameters(Ctx, Spec->getArg(I), OnlyDeduced, Depth,
5987 MarkUsedTemplateParameters(Ctx,
5988 cast<TypeOfType>(T)->getUnderlyingType(),
5989 OnlyDeduced, Depth, Used);
5992 case Type::TypeOfExpr:
5994 MarkUsedTemplateParameters(Ctx,
5995 cast<TypeOfExprType>(T)->getUnderlyingExpr(),
5996 OnlyDeduced, Depth, Used);
5999 case Type::Decltype:
6001 MarkUsedTemplateParameters(Ctx,
6002 cast<DecltypeType>(T)->getUnderlyingExpr(),
6003 OnlyDeduced, Depth, Used);
6006 case Type::UnaryTransform:
6008 MarkUsedTemplateParameters(Ctx,
6009 cast<UnaryTransformType>(T)->getUnderlyingType(),
6010 OnlyDeduced, Depth, Used);
6013 case Type::PackExpansion:
6014 MarkUsedTemplateParameters(Ctx,
6015 cast<PackExpansionType>(T)->getPattern(),
6016 OnlyDeduced, Depth, Used);
6020 case Type::DeducedTemplateSpecialization:
6021 MarkUsedTemplateParameters(Ctx,
6022 cast<DeducedType>(T)->getDeducedType(),
6023 OnlyDeduced, Depth, Used);
6025 case Type::DependentExtInt:
6026 MarkUsedTemplateParameters(Ctx,
6027 cast<DependentExtIntType>(T)->getNumBitsExpr(),
6028 OnlyDeduced, Depth, Used);
6031 // None of these types have any template parameters in them.
6033 case Type::VariableArray:
6034 case Type::FunctionNoProto:
6037 case Type::ObjCInterface:
6038 case Type::ObjCObject:
6039 case Type::ObjCObjectPointer:
6040 case Type::UnresolvedUsing:
6043 #define TYPE(Class, Base)
6044 #define ABSTRACT_TYPE(Class, Base)
6045 #define DEPENDENT_TYPE(Class, Base)
6046 #define NON_CANONICAL_TYPE(Class, Base) case Type::Class:
6047 #include "clang/AST/TypeNodes.inc"
6052 /// Mark the template parameters that are used by this
6053 /// template argument.
6055 MarkUsedTemplateParameters(ASTContext &Ctx,
6056 const TemplateArgument &TemplateArg,
6059 llvm::SmallBitVector &Used) {
6060 switch (TemplateArg.getKind()) {
6061 case TemplateArgument::Null:
6062 case TemplateArgument::Integral:
6063 case TemplateArgument::Declaration:
6066 case TemplateArgument::NullPtr:
6067 MarkUsedTemplateParameters(Ctx, TemplateArg.getNullPtrType(), OnlyDeduced,
6071 case TemplateArgument::Type:
6072 MarkUsedTemplateParameters(Ctx, TemplateArg.getAsType(), OnlyDeduced,
6076 case TemplateArgument::Template:
6077 case TemplateArgument::TemplateExpansion:
6078 MarkUsedTemplateParameters(Ctx,
6079 TemplateArg.getAsTemplateOrTemplatePattern(),
6080 OnlyDeduced, Depth, Used);
6083 case TemplateArgument::Expression:
6084 MarkUsedTemplateParameters(Ctx, TemplateArg.getAsExpr(), OnlyDeduced,
6088 case TemplateArgument::Pack:
6089 for (const auto &P : TemplateArg.pack_elements())
6090 MarkUsedTemplateParameters(Ctx, P, OnlyDeduced, Depth, Used);
6095 /// Mark which template parameters are used in a given expression.
6097 /// \param E the expression from which template parameters will be deduced.
6099 /// \param Used a bit vector whose elements will be set to \c true
6100 /// to indicate when the corresponding template parameter will be
6103 Sema::MarkUsedTemplateParameters(const Expr *E, bool OnlyDeduced,
6105 llvm::SmallBitVector &Used) {
6106 ::MarkUsedTemplateParameters(Context, E, OnlyDeduced, Depth, Used);
6109 /// Mark which template parameters can be deduced from a given
6110 /// template argument list.
6112 /// \param TemplateArgs the template argument list from which template
6113 /// parameters will be deduced.
6115 /// \param Used a bit vector whose elements will be set to \c true
6116 /// to indicate when the corresponding template parameter will be
6119 Sema::MarkUsedTemplateParameters(const TemplateArgumentList &TemplateArgs,
6120 bool OnlyDeduced, unsigned Depth,
6121 llvm::SmallBitVector &Used) {
6122 // C++0x [temp.deduct.type]p9:
6123 // If the template argument list of P contains a pack expansion that is not
6124 // the last template argument, the entire template argument list is a
6125 // non-deduced context.
6127 hasPackExpansionBeforeEnd(TemplateArgs.asArray()))
6130 for (unsigned I = 0, N = TemplateArgs.size(); I != N; ++I)
6131 ::MarkUsedTemplateParameters(Context, TemplateArgs[I], OnlyDeduced,
6135 /// Marks all of the template parameters that will be deduced by a
6136 /// call to the given function template.
6137 void Sema::MarkDeducedTemplateParameters(
6138 ASTContext &Ctx, const FunctionTemplateDecl *FunctionTemplate,
6139 llvm::SmallBitVector &Deduced) {
6140 TemplateParameterList *TemplateParams
6141 = FunctionTemplate->getTemplateParameters();
6143 Deduced.resize(TemplateParams->size());
6145 FunctionDecl *Function = FunctionTemplate->getTemplatedDecl();
6146 for (unsigned I = 0, N = Function->getNumParams(); I != N; ++I)
6147 ::MarkUsedTemplateParameters(Ctx, Function->getParamDecl(I)->getType(),
6148 true, TemplateParams->getDepth(), Deduced);
6151 bool hasDeducibleTemplateParameters(Sema &S,
6152 FunctionTemplateDecl *FunctionTemplate,
6154 if (!T->isDependentType())
6157 TemplateParameterList *TemplateParams
6158 = FunctionTemplate->getTemplateParameters();
6159 llvm::SmallBitVector Deduced(TemplateParams->size());
6160 ::MarkUsedTemplateParameters(S.Context, T, true, TemplateParams->getDepth(),
6163 return Deduced.any();