1 //===- SemaTemplateDeduction.cpp - Template Argument Deduction ------------===//
3 // The LLVM Compiler Infrastructure
5 // This file is distributed under the University of Illinois Open Source
6 // License. See LICENSE.TXT for details.
8 //===----------------------------------------------------------------------===//
10 // This file implements C++ template argument deduction.
12 //===----------------------------------------------------------------------===//
14 #include "clang/Sema/TemplateDeduction.h"
15 #include "TreeTransform.h"
16 #include "TypeLocBuilder.h"
17 #include "clang/AST/ASTContext.h"
18 #include "clang/AST/ASTLambda.h"
19 #include "clang/AST/Decl.h"
20 #include "clang/AST/DeclAccessPair.h"
21 #include "clang/AST/DeclBase.h"
22 #include "clang/AST/DeclCXX.h"
23 #include "clang/AST/DeclTemplate.h"
24 #include "clang/AST/DeclarationName.h"
25 #include "clang/AST/Expr.h"
26 #include "clang/AST/ExprCXX.h"
27 #include "clang/AST/NestedNameSpecifier.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 (SubstNonTypeTemplateParmExpr *Subst =
182 dyn_cast<SubstNonTypeTemplateParmExpr>(E))
183 E = Subst->getReplacement();
188 if (DeclRefExpr *DRE = dyn_cast<DeclRefExpr>(E))
189 if (auto *NTTP = dyn_cast<NonTypeTemplateParmDecl>(DRE->getDecl()))
190 if (NTTP->getDepth() == Info.getDeducedDepth())
196 /// Determine whether two declaration pointers refer to the same
198 static bool isSameDeclaration(Decl *X, Decl *Y) {
199 if (NamedDecl *NX = dyn_cast<NamedDecl>(X))
200 X = NX->getUnderlyingDecl();
201 if (NamedDecl *NY = dyn_cast<NamedDecl>(Y))
202 Y = NY->getUnderlyingDecl();
204 return X->getCanonicalDecl() == Y->getCanonicalDecl();
207 /// Verify that the given, deduced template arguments are compatible.
209 /// \returns The deduced template argument, or a NULL template argument if
210 /// the deduced template arguments were incompatible.
211 static DeducedTemplateArgument
212 checkDeducedTemplateArguments(ASTContext &Context,
213 const DeducedTemplateArgument &X,
214 const DeducedTemplateArgument &Y) {
215 // We have no deduction for one or both of the arguments; they're compatible.
221 // If we have two non-type template argument values deduced for the same
222 // parameter, they must both match the type of the parameter, and thus must
223 // match each other's type. As we're only keeping one of them, we must check
224 // for that now. The exception is that if either was deduced from an array
225 // bound, the type is permitted to differ.
226 if (!X.wasDeducedFromArrayBound() && !Y.wasDeducedFromArrayBound()) {
227 QualType XType = X.getNonTypeTemplateArgumentType();
228 if (!XType.isNull()) {
229 QualType YType = Y.getNonTypeTemplateArgumentType();
230 if (YType.isNull() || !Context.hasSameType(XType, YType))
231 return DeducedTemplateArgument();
235 switch (X.getKind()) {
236 case TemplateArgument::Null:
237 llvm_unreachable("Non-deduced template arguments handled above");
239 case TemplateArgument::Type:
240 // If two template type arguments have the same type, they're compatible.
241 if (Y.getKind() == TemplateArgument::Type &&
242 Context.hasSameType(X.getAsType(), Y.getAsType()))
245 // If one of the two arguments was deduced from an array bound, the other
247 if (X.wasDeducedFromArrayBound() != Y.wasDeducedFromArrayBound())
248 return X.wasDeducedFromArrayBound() ? Y : X;
250 // The arguments are not compatible.
251 return DeducedTemplateArgument();
253 case TemplateArgument::Integral:
254 // If we deduced a constant in one case and either a dependent expression or
255 // declaration in another case, keep the integral constant.
256 // If both are integral constants with the same value, keep that value.
257 if (Y.getKind() == TemplateArgument::Expression ||
258 Y.getKind() == TemplateArgument::Declaration ||
259 (Y.getKind() == TemplateArgument::Integral &&
260 hasSameExtendedValue(X.getAsIntegral(), Y.getAsIntegral())))
261 return X.wasDeducedFromArrayBound() ? Y : X;
263 // All other combinations are incompatible.
264 return DeducedTemplateArgument();
266 case TemplateArgument::Template:
267 if (Y.getKind() == TemplateArgument::Template &&
268 Context.hasSameTemplateName(X.getAsTemplate(), Y.getAsTemplate()))
271 // All other combinations are incompatible.
272 return DeducedTemplateArgument();
274 case TemplateArgument::TemplateExpansion:
275 if (Y.getKind() == TemplateArgument::TemplateExpansion &&
276 Context.hasSameTemplateName(X.getAsTemplateOrTemplatePattern(),
277 Y.getAsTemplateOrTemplatePattern()))
280 // All other combinations are incompatible.
281 return DeducedTemplateArgument();
283 case TemplateArgument::Expression: {
284 if (Y.getKind() != TemplateArgument::Expression)
285 return checkDeducedTemplateArguments(Context, Y, X);
287 // Compare the expressions for equality
288 llvm::FoldingSetNodeID ID1, ID2;
289 X.getAsExpr()->Profile(ID1, Context, true);
290 Y.getAsExpr()->Profile(ID2, Context, true);
292 return X.wasDeducedFromArrayBound() ? Y : X;
294 // Differing dependent expressions are incompatible.
295 return DeducedTemplateArgument();
298 case TemplateArgument::Declaration:
299 assert(!X.wasDeducedFromArrayBound());
301 // If we deduced a declaration and a dependent expression, keep the
303 if (Y.getKind() == TemplateArgument::Expression)
306 // If we deduced a declaration and an integral constant, keep the
307 // integral constant and whichever type did not come from an array
309 if (Y.getKind() == TemplateArgument::Integral) {
310 if (Y.wasDeducedFromArrayBound())
311 return TemplateArgument(Context, Y.getAsIntegral(),
312 X.getParamTypeForDecl());
316 // If we deduced two declarations, make sure that they refer to the
318 if (Y.getKind() == TemplateArgument::Declaration &&
319 isSameDeclaration(X.getAsDecl(), Y.getAsDecl()))
322 // All other combinations are incompatible.
323 return DeducedTemplateArgument();
325 case TemplateArgument::NullPtr:
326 // If we deduced a null pointer and a dependent expression, keep the
328 if (Y.getKind() == TemplateArgument::Expression)
331 // If we deduced a null pointer and an integral constant, keep the
332 // integral constant.
333 if (Y.getKind() == TemplateArgument::Integral)
336 // If we deduced two null pointers, they are the same.
337 if (Y.getKind() == TemplateArgument::NullPtr)
340 // All other combinations are incompatible.
341 return DeducedTemplateArgument();
343 case TemplateArgument::Pack: {
344 if (Y.getKind() != TemplateArgument::Pack ||
345 X.pack_size() != Y.pack_size())
346 return DeducedTemplateArgument();
348 llvm::SmallVector<TemplateArgument, 8> NewPack;
349 for (TemplateArgument::pack_iterator XA = X.pack_begin(),
350 XAEnd = X.pack_end(),
352 XA != XAEnd; ++XA, ++YA) {
353 TemplateArgument Merged = checkDeducedTemplateArguments(
354 Context, DeducedTemplateArgument(*XA, X.wasDeducedFromArrayBound()),
355 DeducedTemplateArgument(*YA, Y.wasDeducedFromArrayBound()));
357 return DeducedTemplateArgument();
358 NewPack.push_back(Merged);
361 return DeducedTemplateArgument(
362 TemplateArgument::CreatePackCopy(Context, NewPack),
363 X.wasDeducedFromArrayBound() && Y.wasDeducedFromArrayBound());
367 llvm_unreachable("Invalid TemplateArgument Kind!");
370 /// Deduce the value of the given non-type template parameter
371 /// as the given deduced template argument. All non-type template parameter
372 /// deduction is funneled through here.
373 static Sema::TemplateDeductionResult DeduceNonTypeTemplateArgument(
374 Sema &S, TemplateParameterList *TemplateParams,
375 NonTypeTemplateParmDecl *NTTP, const DeducedTemplateArgument &NewDeduced,
376 QualType ValueType, TemplateDeductionInfo &Info,
377 SmallVectorImpl<DeducedTemplateArgument> &Deduced) {
378 assert(NTTP->getDepth() == Info.getDeducedDepth() &&
379 "deducing non-type template argument with wrong depth");
381 DeducedTemplateArgument Result = checkDeducedTemplateArguments(
382 S.Context, Deduced[NTTP->getIndex()], NewDeduced);
383 if (Result.isNull()) {
385 Info.FirstArg = Deduced[NTTP->getIndex()];
386 Info.SecondArg = NewDeduced;
387 return Sema::TDK_Inconsistent;
390 Deduced[NTTP->getIndex()] = Result;
391 if (!S.getLangOpts().CPlusPlus17)
392 return Sema::TDK_Success;
394 if (NTTP->isExpandedParameterPack())
395 // FIXME: We may still need to deduce parts of the type here! But we
396 // don't have any way to find which slice of the type to use, and the
397 // type stored on the NTTP itself is nonsense. Perhaps the type of an
398 // expanded NTTP should be a pack expansion type?
399 return Sema::TDK_Success;
401 // Get the type of the parameter for deduction. If it's a (dependent) array
402 // or function type, we will not have decayed it yet, so do that now.
403 QualType ParamType = S.Context.getAdjustedParameterType(NTTP->getType());
404 if (auto *Expansion = dyn_cast<PackExpansionType>(ParamType))
405 ParamType = Expansion->getPattern();
407 // FIXME: It's not clear how deduction of a parameter of reference
408 // type from an argument (of non-reference type) should be performed.
409 // For now, we just remove reference types from both sides and let
410 // the final check for matching types sort out the mess.
411 return DeduceTemplateArgumentsByTypeMatch(
412 S, TemplateParams, ParamType.getNonReferenceType(),
413 ValueType.getNonReferenceType(), Info, Deduced, TDF_SkipNonDependent,
414 /*PartialOrdering=*/false,
415 /*ArrayBound=*/NewDeduced.wasDeducedFromArrayBound());
418 /// Deduce the value of the given non-type template parameter
419 /// from the given integral constant.
420 static Sema::TemplateDeductionResult DeduceNonTypeTemplateArgument(
421 Sema &S, TemplateParameterList *TemplateParams,
422 NonTypeTemplateParmDecl *NTTP, const llvm::APSInt &Value,
423 QualType ValueType, bool DeducedFromArrayBound, TemplateDeductionInfo &Info,
424 SmallVectorImpl<DeducedTemplateArgument> &Deduced) {
425 return DeduceNonTypeTemplateArgument(
426 S, TemplateParams, NTTP,
427 DeducedTemplateArgument(S.Context, Value, ValueType,
428 DeducedFromArrayBound),
429 ValueType, Info, Deduced);
432 /// Deduce the value of the given non-type template parameter
433 /// from the given null pointer template argument type.
434 static Sema::TemplateDeductionResult DeduceNullPtrTemplateArgument(
435 Sema &S, TemplateParameterList *TemplateParams,
436 NonTypeTemplateParmDecl *NTTP, QualType NullPtrType,
437 TemplateDeductionInfo &Info,
438 SmallVectorImpl<DeducedTemplateArgument> &Deduced) {
440 S.ImpCastExprToType(new (S.Context) CXXNullPtrLiteralExpr(
441 S.Context.NullPtrTy, NTTP->getLocation()),
442 NullPtrType, CK_NullToPointer)
444 return DeduceNonTypeTemplateArgument(S, TemplateParams, NTTP,
445 DeducedTemplateArgument(Value),
446 Value->getType(), Info, Deduced);
449 /// Deduce the value of the given non-type template parameter
450 /// from the given type- or value-dependent expression.
452 /// \returns true if deduction succeeded, false otherwise.
453 static Sema::TemplateDeductionResult DeduceNonTypeTemplateArgument(
454 Sema &S, TemplateParameterList *TemplateParams,
455 NonTypeTemplateParmDecl *NTTP, Expr *Value, TemplateDeductionInfo &Info,
456 SmallVectorImpl<DeducedTemplateArgument> &Deduced) {
457 return DeduceNonTypeTemplateArgument(S, TemplateParams, NTTP,
458 DeducedTemplateArgument(Value),
459 Value->getType(), Info, Deduced);
462 /// Deduce the value of the given non-type template parameter
463 /// from the given declaration.
465 /// \returns true if deduction succeeded, false otherwise.
466 static Sema::TemplateDeductionResult DeduceNonTypeTemplateArgument(
467 Sema &S, TemplateParameterList *TemplateParams,
468 NonTypeTemplateParmDecl *NTTP, ValueDecl *D, QualType T,
469 TemplateDeductionInfo &Info,
470 SmallVectorImpl<DeducedTemplateArgument> &Deduced) {
471 D = D ? cast<ValueDecl>(D->getCanonicalDecl()) : nullptr;
472 TemplateArgument New(D, T);
473 return DeduceNonTypeTemplateArgument(
474 S, TemplateParams, NTTP, DeducedTemplateArgument(New), T, Info, Deduced);
477 static Sema::TemplateDeductionResult
478 DeduceTemplateArguments(Sema &S,
479 TemplateParameterList *TemplateParams,
482 TemplateDeductionInfo &Info,
483 SmallVectorImpl<DeducedTemplateArgument> &Deduced) {
484 TemplateDecl *ParamDecl = Param.getAsTemplateDecl();
486 // The parameter type is dependent and is not a template template parameter,
487 // so there is nothing that we can deduce.
488 return Sema::TDK_Success;
491 if (TemplateTemplateParmDecl *TempParam
492 = dyn_cast<TemplateTemplateParmDecl>(ParamDecl)) {
493 // If we're not deducing at this depth, there's nothing to deduce.
494 if (TempParam->getDepth() != Info.getDeducedDepth())
495 return Sema::TDK_Success;
497 DeducedTemplateArgument NewDeduced(S.Context.getCanonicalTemplateName(Arg));
498 DeducedTemplateArgument Result = checkDeducedTemplateArguments(S.Context,
499 Deduced[TempParam->getIndex()],
501 if (Result.isNull()) {
502 Info.Param = TempParam;
503 Info.FirstArg = Deduced[TempParam->getIndex()];
504 Info.SecondArg = NewDeduced;
505 return Sema::TDK_Inconsistent;
508 Deduced[TempParam->getIndex()] = Result;
509 return Sema::TDK_Success;
512 // Verify that the two template names are equivalent.
513 if (S.Context.hasSameTemplateName(Param, Arg))
514 return Sema::TDK_Success;
516 // Mismatch of non-dependent template parameter to argument.
517 Info.FirstArg = TemplateArgument(Param);
518 Info.SecondArg = TemplateArgument(Arg);
519 return Sema::TDK_NonDeducedMismatch;
522 /// Deduce the template arguments by comparing the template parameter
523 /// type (which is a template-id) with the template argument type.
525 /// \param S the Sema
527 /// \param TemplateParams the template parameters that we are deducing
529 /// \param Param the parameter type
531 /// \param Arg the argument type
533 /// \param Info information about the template argument deduction itself
535 /// \param Deduced the deduced template arguments
537 /// \returns the result of template argument deduction so far. Note that a
538 /// "success" result means that template argument deduction has not yet failed,
539 /// but it may still fail, later, for other reasons.
540 static Sema::TemplateDeductionResult
541 DeduceTemplateArguments(Sema &S,
542 TemplateParameterList *TemplateParams,
543 const TemplateSpecializationType *Param,
545 TemplateDeductionInfo &Info,
546 SmallVectorImpl<DeducedTemplateArgument> &Deduced) {
547 assert(Arg.isCanonical() && "Argument type must be canonical");
549 // Treat an injected-class-name as its underlying template-id.
550 if (auto *Injected = dyn_cast<InjectedClassNameType>(Arg))
551 Arg = Injected->getInjectedSpecializationType();
553 // Check whether the template argument is a dependent template-id.
554 if (const TemplateSpecializationType *SpecArg
555 = dyn_cast<TemplateSpecializationType>(Arg)) {
556 // Perform template argument deduction for the template name.
557 if (Sema::TemplateDeductionResult Result
558 = DeduceTemplateArguments(S, TemplateParams,
559 Param->getTemplateName(),
560 SpecArg->getTemplateName(),
565 // Perform template argument deduction on each template
566 // argument. Ignore any missing/extra arguments, since they could be
567 // filled in by default arguments.
568 return DeduceTemplateArguments(S, TemplateParams,
569 Param->template_arguments(),
570 SpecArg->template_arguments(), Info, Deduced,
571 /*NumberOfArgumentsMustMatch=*/false);
574 // If the argument type is a class template specialization, we
575 // perform template argument deduction using its template
577 const RecordType *RecordArg = dyn_cast<RecordType>(Arg);
579 Info.FirstArg = TemplateArgument(QualType(Param, 0));
580 Info.SecondArg = TemplateArgument(Arg);
581 return Sema::TDK_NonDeducedMismatch;
584 ClassTemplateSpecializationDecl *SpecArg
585 = dyn_cast<ClassTemplateSpecializationDecl>(RecordArg->getDecl());
587 Info.FirstArg = TemplateArgument(QualType(Param, 0));
588 Info.SecondArg = TemplateArgument(Arg);
589 return Sema::TDK_NonDeducedMismatch;
592 // Perform template argument deduction for the template name.
593 if (Sema::TemplateDeductionResult Result
594 = DeduceTemplateArguments(S,
596 Param->getTemplateName(),
597 TemplateName(SpecArg->getSpecializedTemplate()),
601 // Perform template argument deduction for the template arguments.
602 return DeduceTemplateArguments(S, TemplateParams, Param->template_arguments(),
603 SpecArg->getTemplateArgs().asArray(), Info,
604 Deduced, /*NumberOfArgumentsMustMatch=*/true);
607 /// Determines whether the given type is an opaque type that
608 /// might be more qualified when instantiated.
609 static bool IsPossiblyOpaquelyQualifiedType(QualType T) {
610 switch (T->getTypeClass()) {
611 case Type::TypeOfExpr:
613 case Type::DependentName:
615 case Type::UnresolvedUsing:
616 case Type::TemplateTypeParm:
619 case Type::ConstantArray:
620 case Type::IncompleteArray:
621 case Type::VariableArray:
622 case Type::DependentSizedArray:
623 return IsPossiblyOpaquelyQualifiedType(
624 cast<ArrayType>(T)->getElementType());
631 /// Helper function to build a TemplateParameter when we don't
632 /// know its type statically.
633 static TemplateParameter makeTemplateParameter(Decl *D) {
634 if (TemplateTypeParmDecl *TTP = dyn_cast<TemplateTypeParmDecl>(D))
635 return TemplateParameter(TTP);
636 if (NonTypeTemplateParmDecl *NTTP = dyn_cast<NonTypeTemplateParmDecl>(D))
637 return TemplateParameter(NTTP);
639 return TemplateParameter(cast<TemplateTemplateParmDecl>(D));
642 /// If \p Param is an expanded parameter pack, get the number of expansions.
643 static Optional<unsigned> getExpandedPackSize(NamedDecl *Param) {
644 if (auto *NTTP = dyn_cast<NonTypeTemplateParmDecl>(Param))
645 if (NTTP->isExpandedParameterPack())
646 return NTTP->getNumExpansionTypes();
648 if (auto *TTP = dyn_cast<TemplateTemplateParmDecl>(Param))
649 if (TTP->isExpandedParameterPack())
650 return TTP->getNumExpansionTemplateParameters();
655 /// A pack that we're currently deducing.
656 struct clang::DeducedPack {
657 // The index of the pack.
660 // The old value of the pack before we started deducing it.
661 DeducedTemplateArgument Saved;
663 // A deferred value of this pack from an inner deduction, that couldn't be
664 // deduced because this deduction hadn't happened yet.
665 DeducedTemplateArgument DeferredDeduction;
667 // The new value of the pack.
668 SmallVector<DeducedTemplateArgument, 4> New;
670 // The outer deduction for this pack, if any.
671 DeducedPack *Outer = nullptr;
673 DeducedPack(unsigned Index) : Index(Index) {}
678 /// A scope in which we're performing pack deduction.
679 class PackDeductionScope {
681 /// Prepare to deduce the packs named within Pattern.
682 PackDeductionScope(Sema &S, TemplateParameterList *TemplateParams,
683 SmallVectorImpl<DeducedTemplateArgument> &Deduced,
684 TemplateDeductionInfo &Info, TemplateArgument Pattern)
685 : S(S), TemplateParams(TemplateParams), Deduced(Deduced), Info(Info) {
686 unsigned NumNamedPacks = addPacks(Pattern);
687 finishConstruction(NumNamedPacks);
690 /// Prepare to directly deduce arguments of the parameter with index \p Index.
691 PackDeductionScope(Sema &S, TemplateParameterList *TemplateParams,
692 SmallVectorImpl<DeducedTemplateArgument> &Deduced,
693 TemplateDeductionInfo &Info, unsigned Index)
694 : S(S), TemplateParams(TemplateParams), Deduced(Deduced), Info(Info) {
696 finishConstruction(1);
700 void addPack(unsigned Index) {
701 // Save the deduced template argument for the parameter pack expanded
702 // by this pack expansion, then clear out the deduction.
703 DeducedPack Pack(Index);
704 Pack.Saved = Deduced[Index];
705 Deduced[Index] = TemplateArgument();
707 // FIXME: What if we encounter multiple packs with different numbers of
708 // pre-expanded expansions? (This should already have been diagnosed
709 // during substitution.)
710 if (Optional<unsigned> ExpandedPackExpansions =
711 getExpandedPackSize(TemplateParams->getParam(Index)))
712 FixedNumExpansions = ExpandedPackExpansions;
714 Packs.push_back(Pack);
717 unsigned addPacks(TemplateArgument Pattern) {
718 // Compute the set of template parameter indices that correspond to
719 // parameter packs expanded by the pack expansion.
720 llvm::SmallBitVector SawIndices(TemplateParams->size());
722 auto AddPack = [&](unsigned Index) {
723 if (SawIndices[Index])
725 SawIndices[Index] = true;
729 // First look for unexpanded packs in the pattern.
730 SmallVector<UnexpandedParameterPack, 2> Unexpanded;
731 S.collectUnexpandedParameterPacks(Pattern, Unexpanded);
732 for (unsigned I = 0, N = Unexpanded.size(); I != N; ++I) {
733 unsigned Depth, Index;
734 std::tie(Depth, Index) = getDepthAndIndex(Unexpanded[I]);
735 if (Depth == Info.getDeducedDepth())
738 assert(!Packs.empty() && "Pack expansion without unexpanded packs?");
740 unsigned NumNamedPacks = Packs.size();
742 // We can also have deduced template parameters that do not actually
743 // appear in the pattern, but can be deduced by it (the type of a non-type
744 // template parameter pack, in particular). These won't have prevented us
745 // from partially expanding the pack.
746 llvm::SmallBitVector Used(TemplateParams->size());
747 MarkUsedTemplateParameters(S.Context, Pattern, /*OnlyDeduced*/true,
748 Info.getDeducedDepth(), Used);
749 for (int Index = Used.find_first(); Index != -1;
750 Index = Used.find_next(Index))
751 if (TemplateParams->getParam(Index)->isParameterPack())
754 return NumNamedPacks;
757 void finishConstruction(unsigned NumNamedPacks) {
758 // Dig out the partially-substituted pack, if there is one.
759 const TemplateArgument *PartialPackArgs = nullptr;
760 unsigned NumPartialPackArgs = 0;
761 std::pair<unsigned, unsigned> PartialPackDepthIndex(-1u, -1u);
762 if (auto *Scope = S.CurrentInstantiationScope)
763 if (auto *Partial = Scope->getPartiallySubstitutedPack(
764 &PartialPackArgs, &NumPartialPackArgs))
765 PartialPackDepthIndex = getDepthAndIndex(Partial);
767 // This pack expansion will have been partially or fully expanded if
768 // it only names explicitly-specified parameter packs (including the
769 // partially-substituted one, if any).
770 bool IsExpanded = true;
771 for (unsigned I = 0; I != NumNamedPacks; ++I) {
772 if (Packs[I].Index >= Info.getNumExplicitArgs()) {
774 IsPartiallyExpanded = false;
777 if (PartialPackDepthIndex ==
778 std::make_pair(Info.getDeducedDepth(), Packs[I].Index)) {
779 IsPartiallyExpanded = true;
783 // Skip over the pack elements that were expanded into separate arguments.
784 // If we partially expanded, this is the number of partial arguments.
785 if (IsPartiallyExpanded)
786 PackElements += NumPartialPackArgs;
788 PackElements += *FixedNumExpansions;
790 for (auto &Pack : Packs) {
791 if (Info.PendingDeducedPacks.size() > Pack.Index)
792 Pack.Outer = Info.PendingDeducedPacks[Pack.Index];
794 Info.PendingDeducedPacks.resize(Pack.Index + 1);
795 Info.PendingDeducedPacks[Pack.Index] = &Pack;
797 if (PartialPackDepthIndex ==
798 std::make_pair(Info.getDeducedDepth(), Pack.Index)) {
799 Pack.New.append(PartialPackArgs, PartialPackArgs + NumPartialPackArgs);
800 // We pre-populate the deduced value of the partially-substituted
801 // pack with the specified value. This is not entirely correct: the
802 // value is supposed to have been substituted, not deduced, but the
803 // cases where this is observable require an exact type match anyway.
805 // FIXME: If we could represent a "depth i, index j, pack elem k"
806 // parameter, we could substitute the partially-substituted pack
807 // everywhere and avoid this.
808 if (!IsPartiallyExpanded)
809 Deduced[Pack.Index] = Pack.New[PackElements];
815 ~PackDeductionScope() {
816 for (auto &Pack : Packs)
817 Info.PendingDeducedPacks[Pack.Index] = Pack.Outer;
820 /// Determine whether this pack has already been partially expanded into a
821 /// sequence of (prior) function parameters / template arguments.
822 bool isPartiallyExpanded() { return IsPartiallyExpanded; }
824 /// Determine whether this pack expansion scope has a known, fixed arity.
825 /// This happens if it involves a pack from an outer template that has
826 /// (notionally) already been expanded.
827 bool hasFixedArity() { return FixedNumExpansions.hasValue(); }
829 /// Determine whether the next element of the argument is still part of this
830 /// pack. This is the case unless the pack is already expanded to a fixed
832 bool hasNextElement() {
833 return !FixedNumExpansions || *FixedNumExpansions > PackElements;
836 /// Move to deducing the next element in each pack that is being deduced.
837 void nextPackElement() {
838 // Capture the deduced template arguments for each parameter pack expanded
839 // by this pack expansion, add them to the list of arguments we've deduced
840 // for that pack, then clear out the deduced argument.
841 for (auto &Pack : Packs) {
842 DeducedTemplateArgument &DeducedArg = Deduced[Pack.Index];
843 if (!Pack.New.empty() || !DeducedArg.isNull()) {
844 while (Pack.New.size() < PackElements)
845 Pack.New.push_back(DeducedTemplateArgument());
846 if (Pack.New.size() == PackElements)
847 Pack.New.push_back(DeducedArg);
849 Pack.New[PackElements] = DeducedArg;
850 DeducedArg = Pack.New.size() > PackElements + 1
851 ? Pack.New[PackElements + 1]
852 : DeducedTemplateArgument();
858 /// Finish template argument deduction for a set of argument packs,
859 /// producing the argument packs and checking for consistency with prior
861 Sema::TemplateDeductionResult
862 finish(bool TreatNoDeductionsAsNonDeduced = true) {
863 // Build argument packs for each of the parameter packs expanded by this
865 for (auto &Pack : Packs) {
866 // Put back the old value for this pack.
867 Deduced[Pack.Index] = Pack.Saved;
869 // If we are deducing the size of this pack even if we didn't deduce any
870 // values for it, then make sure we build a pack of the right size.
871 // FIXME: Should we always deduce the size, even if the pack appears in
872 // a non-deduced context?
873 if (!TreatNoDeductionsAsNonDeduced)
874 Pack.New.resize(PackElements);
876 // Build or find a new value for this pack.
877 DeducedTemplateArgument NewPack;
878 if (PackElements && Pack.New.empty()) {
879 if (Pack.DeferredDeduction.isNull()) {
880 // We were not able to deduce anything for this parameter pack
881 // (because it only appeared in non-deduced contexts), so just
882 // restore the saved argument pack.
886 NewPack = Pack.DeferredDeduction;
887 Pack.DeferredDeduction = TemplateArgument();
888 } else if (Pack.New.empty()) {
889 // If we deduced an empty argument pack, create it now.
890 NewPack = DeducedTemplateArgument(TemplateArgument::getEmptyPack());
892 TemplateArgument *ArgumentPack =
893 new (S.Context) TemplateArgument[Pack.New.size()];
894 std::copy(Pack.New.begin(), Pack.New.end(), ArgumentPack);
895 NewPack = DeducedTemplateArgument(
896 TemplateArgument(llvm::makeArrayRef(ArgumentPack, Pack.New.size())),
897 // FIXME: This is wrong, it's possible that some pack elements are
898 // deduced from an array bound and others are not:
899 // template<typename ...T, T ...V> void g(const T (&...p)[V]);
900 // g({1, 2, 3}, {{}, {}});
901 // ... should deduce T = {int, size_t (from array bound)}.
902 Pack.New[0].wasDeducedFromArrayBound());
905 // Pick where we're going to put the merged pack.
906 DeducedTemplateArgument *Loc;
908 if (Pack.Outer->DeferredDeduction.isNull()) {
909 // Defer checking this pack until we have a complete pack to compare
911 Pack.Outer->DeferredDeduction = NewPack;
914 Loc = &Pack.Outer->DeferredDeduction;
916 Loc = &Deduced[Pack.Index];
919 // Check the new pack matches any previous value.
920 DeducedTemplateArgument OldPack = *Loc;
921 DeducedTemplateArgument Result =
922 checkDeducedTemplateArguments(S.Context, OldPack, NewPack);
924 // If we deferred a deduction of this pack, check that one now too.
925 if (!Result.isNull() && !Pack.DeferredDeduction.isNull()) {
927 NewPack = Pack.DeferredDeduction;
928 Result = checkDeducedTemplateArguments(S.Context, OldPack, NewPack);
931 NamedDecl *Param = TemplateParams->getParam(Pack.Index);
932 if (Result.isNull()) {
933 Info.Param = makeTemplateParameter(Param);
934 Info.FirstArg = OldPack;
935 Info.SecondArg = NewPack;
936 return Sema::TDK_Inconsistent;
939 // If we have a pre-expanded pack and we didn't deduce enough elements
940 // for it, fail deduction.
941 if (Optional<unsigned> Expansions = getExpandedPackSize(Param)) {
942 if (*Expansions != PackElements) {
943 Info.Param = makeTemplateParameter(Param);
944 Info.FirstArg = Result;
945 return Sema::TDK_IncompletePack;
952 return Sema::TDK_Success;
957 TemplateParameterList *TemplateParams;
958 SmallVectorImpl<DeducedTemplateArgument> &Deduced;
959 TemplateDeductionInfo &Info;
960 unsigned PackElements = 0;
961 bool IsPartiallyExpanded = false;
962 /// The number of expansions, if we have a fully-expanded pack in this scope.
963 Optional<unsigned> FixedNumExpansions;
965 SmallVector<DeducedPack, 2> Packs;
970 /// Deduce the template arguments by comparing the list of parameter
971 /// types to the list of argument types, as in the parameter-type-lists of
972 /// function types (C++ [temp.deduct.type]p10).
974 /// \param S The semantic analysis object within which we are deducing
976 /// \param TemplateParams The template parameters that we are deducing
978 /// \param Params The list of parameter types
980 /// \param NumParams The number of types in \c Params
982 /// \param Args The list of argument types
984 /// \param NumArgs The number of types in \c Args
986 /// \param Info information about the template argument deduction itself
988 /// \param Deduced the deduced template arguments
990 /// \param TDF bitwise OR of the TemplateDeductionFlags bits that describe
991 /// how template argument deduction is performed.
993 /// \param PartialOrdering If true, we are performing template argument
994 /// deduction for during partial ordering for a call
995 /// (C++0x [temp.deduct.partial]).
997 /// \returns the result of template argument deduction so far. Note that a
998 /// "success" result means that template argument deduction has not yet failed,
999 /// but it may still fail, later, for other reasons.
1000 static Sema::TemplateDeductionResult
1001 DeduceTemplateArguments(Sema &S,
1002 TemplateParameterList *TemplateParams,
1003 const QualType *Params, unsigned NumParams,
1004 const QualType *Args, unsigned NumArgs,
1005 TemplateDeductionInfo &Info,
1006 SmallVectorImpl<DeducedTemplateArgument> &Deduced,
1008 bool PartialOrdering = false) {
1009 // C++0x [temp.deduct.type]p10:
1010 // Similarly, if P has a form that contains (T), then each parameter type
1011 // Pi of the respective parameter-type- list of P is compared with the
1012 // corresponding parameter type Ai of the corresponding parameter-type-list
1014 unsigned ArgIdx = 0, ParamIdx = 0;
1015 for (; ParamIdx != NumParams; ++ParamIdx) {
1016 // Check argument types.
1017 const PackExpansionType *Expansion
1018 = dyn_cast<PackExpansionType>(Params[ParamIdx]);
1020 // Simple case: compare the parameter and argument types at this point.
1022 // Make sure we have an argument.
1023 if (ArgIdx >= NumArgs)
1024 return Sema::TDK_MiscellaneousDeductionFailure;
1026 if (isa<PackExpansionType>(Args[ArgIdx])) {
1027 // C++0x [temp.deduct.type]p22:
1028 // If the original function parameter associated with A is a function
1029 // parameter pack and the function parameter associated with P is not
1030 // a function parameter pack, then template argument deduction fails.
1031 return Sema::TDK_MiscellaneousDeductionFailure;
1034 if (Sema::TemplateDeductionResult Result
1035 = DeduceTemplateArgumentsByTypeMatch(S, TemplateParams,
1036 Params[ParamIdx], Args[ArgIdx],
1045 // C++0x [temp.deduct.type]p10:
1046 // If the parameter-declaration corresponding to Pi is a function
1047 // parameter pack, then the type of its declarator- id is compared with
1048 // each remaining parameter type in the parameter-type-list of A. Each
1049 // comparison deduces template arguments for subsequent positions in the
1050 // template parameter packs expanded by the function parameter pack.
1052 QualType Pattern = Expansion->getPattern();
1053 PackDeductionScope PackScope(S, TemplateParams, Deduced, Info, Pattern);
1055 // A pack scope with fixed arity is not really a pack any more, so is not
1056 // a non-deduced context.
1057 if (ParamIdx + 1 == NumParams || PackScope.hasFixedArity()) {
1058 for (; ArgIdx < NumArgs && PackScope.hasNextElement(); ++ArgIdx) {
1059 // Deduce template arguments from the pattern.
1060 if (Sema::TemplateDeductionResult Result
1061 = DeduceTemplateArgumentsByTypeMatch(S, TemplateParams, Pattern,
1062 Args[ArgIdx], Info, Deduced,
1063 TDF, PartialOrdering))
1066 PackScope.nextPackElement();
1069 // C++0x [temp.deduct.type]p5:
1070 // The non-deduced contexts are:
1071 // - A function parameter pack that does not occur at the end of the
1072 // parameter-declaration-clause.
1074 // FIXME: There is no wording to say what we should do in this case. We
1075 // choose to resolve this by applying the same rule that is applied for a
1076 // function call: that is, deduce all contained packs to their
1077 // explicitly-specified values (or to <> if there is no such value).
1079 // This is seemingly-arbitrarily different from the case of a template-id
1080 // with a non-trailing pack-expansion in its arguments, which renders the
1081 // entire template-argument-list a non-deduced context.
1083 // If the parameter type contains an explicitly-specified pack that we
1084 // could not expand, skip the number of parameters notionally created
1085 // by the expansion.
1086 Optional<unsigned> NumExpansions = Expansion->getNumExpansions();
1087 if (NumExpansions && !PackScope.isPartiallyExpanded()) {
1088 for (unsigned I = 0; I != *NumExpansions && ArgIdx < NumArgs;
1090 PackScope.nextPackElement();
1094 // Build argument packs for each of the parameter packs expanded by this
1096 if (auto Result = PackScope.finish())
1100 // Make sure we don't have any extra arguments.
1101 if (ArgIdx < NumArgs)
1102 return Sema::TDK_MiscellaneousDeductionFailure;
1104 return Sema::TDK_Success;
1107 /// Determine whether the parameter has qualifiers that the argument
1108 /// lacks. Put another way, determine whether there is no way to add
1109 /// a deduced set of qualifiers to the ParamType that would result in
1110 /// its qualifiers matching those of the ArgType.
1111 static bool hasInconsistentOrSupersetQualifiersOf(QualType ParamType,
1113 Qualifiers ParamQs = ParamType.getQualifiers();
1114 Qualifiers ArgQs = ArgType.getQualifiers();
1116 if (ParamQs == ArgQs)
1119 // Mismatched (but not missing) Objective-C GC attributes.
1120 if (ParamQs.getObjCGCAttr() != ArgQs.getObjCGCAttr() &&
1121 ParamQs.hasObjCGCAttr())
1124 // Mismatched (but not missing) address spaces.
1125 if (ParamQs.getAddressSpace() != ArgQs.getAddressSpace() &&
1126 ParamQs.hasAddressSpace())
1129 // Mismatched (but not missing) Objective-C lifetime qualifiers.
1130 if (ParamQs.getObjCLifetime() != ArgQs.getObjCLifetime() &&
1131 ParamQs.hasObjCLifetime())
1134 // CVR qualifiers inconsistent or a superset.
1135 return (ParamQs.getCVRQualifiers() & ~ArgQs.getCVRQualifiers()) != 0;
1138 /// Compare types for equality with respect to possibly compatible
1139 /// function types (noreturn adjustment, implicit calling conventions). If any
1140 /// of parameter and argument is not a function, just perform type comparison.
1142 /// \param Param the template parameter type.
1144 /// \param Arg the argument type.
1145 bool Sema::isSameOrCompatibleFunctionType(CanQualType Param,
1147 const FunctionType *ParamFunction = Param->getAs<FunctionType>(),
1148 *ArgFunction = Arg->getAs<FunctionType>();
1150 // Just compare if not functions.
1151 if (!ParamFunction || !ArgFunction)
1152 return Param == Arg;
1154 // Noreturn and noexcept adjustment.
1155 QualType AdjustedParam;
1156 if (IsFunctionConversion(Param, Arg, AdjustedParam))
1157 return Arg == Context.getCanonicalType(AdjustedParam);
1159 // FIXME: Compatible calling conventions.
1161 return Param == Arg;
1164 /// Get the index of the first template parameter that was originally from the
1165 /// innermost template-parameter-list. This is 0 except when we concatenate
1166 /// the template parameter lists of a class template and a constructor template
1167 /// when forming an implicit deduction guide.
1168 static unsigned getFirstInnerIndex(FunctionTemplateDecl *FTD) {
1169 auto *Guide = dyn_cast<CXXDeductionGuideDecl>(FTD->getTemplatedDecl());
1170 if (!Guide || !Guide->isImplicit())
1172 return Guide->getDeducedTemplate()->getTemplateParameters()->size();
1175 /// Determine whether a type denotes a forwarding reference.
1176 static bool isForwardingReference(QualType Param, unsigned FirstInnerIndex) {
1177 // C++1z [temp.deduct.call]p3:
1178 // A forwarding reference is an rvalue reference to a cv-unqualified
1179 // template parameter that does not represent a template parameter of a
1181 if (auto *ParamRef = Param->getAs<RValueReferenceType>()) {
1182 if (ParamRef->getPointeeType().getQualifiers())
1184 auto *TypeParm = ParamRef->getPointeeType()->getAs<TemplateTypeParmType>();
1185 return TypeParm && TypeParm->getIndex() >= FirstInnerIndex;
1190 /// Deduce the template arguments by comparing the parameter type and
1191 /// the argument type (C++ [temp.deduct.type]).
1193 /// \param S the semantic analysis object within which we are deducing
1195 /// \param TemplateParams the template parameters that we are deducing
1197 /// \param ParamIn the parameter type
1199 /// \param ArgIn the argument type
1201 /// \param Info information about the template argument deduction itself
1203 /// \param Deduced the deduced template arguments
1205 /// \param TDF bitwise OR of the TemplateDeductionFlags bits that describe
1206 /// how template argument deduction is performed.
1208 /// \param PartialOrdering Whether we're performing template argument deduction
1209 /// in the context of partial ordering (C++0x [temp.deduct.partial]).
1211 /// \returns the result of template argument deduction so far. Note that a
1212 /// "success" result means that template argument deduction has not yet failed,
1213 /// but it may still fail, later, for other reasons.
1214 static Sema::TemplateDeductionResult
1215 DeduceTemplateArgumentsByTypeMatch(Sema &S,
1216 TemplateParameterList *TemplateParams,
1217 QualType ParamIn, QualType ArgIn,
1218 TemplateDeductionInfo &Info,
1219 SmallVectorImpl<DeducedTemplateArgument> &Deduced,
1221 bool PartialOrdering,
1222 bool DeducedFromArrayBound) {
1223 // We only want to look at the canonical types, since typedefs and
1224 // sugar are not part of template argument deduction.
1225 QualType Param = S.Context.getCanonicalType(ParamIn);
1226 QualType Arg = S.Context.getCanonicalType(ArgIn);
1228 // If the argument type is a pack expansion, look at its pattern.
1229 // This isn't explicitly called out
1230 if (const PackExpansionType *ArgExpansion
1231 = dyn_cast<PackExpansionType>(Arg))
1232 Arg = ArgExpansion->getPattern();
1234 if (PartialOrdering) {
1235 // C++11 [temp.deduct.partial]p5:
1236 // Before the partial ordering is done, certain transformations are
1237 // performed on the types used for partial ordering:
1238 // - If P is a reference type, P is replaced by the type referred to.
1239 const ReferenceType *ParamRef = Param->getAs<ReferenceType>();
1241 Param = ParamRef->getPointeeType();
1243 // - If A is a reference type, A is replaced by the type referred to.
1244 const ReferenceType *ArgRef = Arg->getAs<ReferenceType>();
1246 Arg = ArgRef->getPointeeType();
1248 if (ParamRef && ArgRef && S.Context.hasSameUnqualifiedType(Param, Arg)) {
1249 // C++11 [temp.deduct.partial]p9:
1250 // If, for a given type, deduction succeeds in both directions (i.e.,
1251 // the types are identical after the transformations above) and both
1252 // P and A were reference types [...]:
1253 // - if [one type] was an lvalue reference and [the other type] was
1254 // not, [the other type] is not considered to be at least as
1255 // specialized as [the first type]
1256 // - if [one type] is more cv-qualified than [the other type],
1257 // [the other type] is not considered to be at least as specialized
1258 // as [the first type]
1259 // Objective-C ARC adds:
1260 // - [one type] has non-trivial lifetime, [the other type] has
1261 // __unsafe_unretained lifetime, and the types are otherwise
1264 // A is "considered to be at least as specialized" as P iff deduction
1265 // succeeds, so we model this as a deduction failure. Note that
1266 // [the first type] is P and [the other type] is A here; the standard
1267 // gets this backwards.
1268 Qualifiers ParamQuals = Param.getQualifiers();
1269 Qualifiers ArgQuals = Arg.getQualifiers();
1270 if ((ParamRef->isLValueReferenceType() &&
1271 !ArgRef->isLValueReferenceType()) ||
1272 ParamQuals.isStrictSupersetOf(ArgQuals) ||
1273 (ParamQuals.hasNonTrivialObjCLifetime() &&
1274 ArgQuals.getObjCLifetime() == Qualifiers::OCL_ExplicitNone &&
1275 ParamQuals.withoutObjCLifetime() ==
1276 ArgQuals.withoutObjCLifetime())) {
1277 Info.FirstArg = TemplateArgument(ParamIn);
1278 Info.SecondArg = TemplateArgument(ArgIn);
1279 return Sema::TDK_NonDeducedMismatch;
1283 // C++11 [temp.deduct.partial]p7:
1284 // Remove any top-level cv-qualifiers:
1285 // - If P is a cv-qualified type, P is replaced by the cv-unqualified
1287 Param = Param.getUnqualifiedType();
1288 // - If A is a cv-qualified type, A is replaced by the cv-unqualified
1290 Arg = Arg.getUnqualifiedType();
1292 // C++0x [temp.deduct.call]p4 bullet 1:
1293 // - If the original P is a reference type, the deduced A (i.e., the type
1294 // referred to by the reference) can be more cv-qualified than the
1296 if (TDF & TDF_ParamWithReferenceType) {
1298 QualType UnqualParam = S.Context.getUnqualifiedArrayType(Param, Quals);
1299 Quals.setCVRQualifiers(Quals.getCVRQualifiers() &
1300 Arg.getCVRQualifiers());
1301 Param = S.Context.getQualifiedType(UnqualParam, Quals);
1304 if ((TDF & TDF_TopLevelParameterTypeList) && !Param->isFunctionType()) {
1305 // C++0x [temp.deduct.type]p10:
1306 // If P and A are function types that originated from deduction when
1307 // taking the address of a function template (14.8.2.2) or when deducing
1308 // template arguments from a function declaration (14.8.2.6) and Pi and
1309 // Ai are parameters of the top-level parameter-type-list of P and A,
1310 // respectively, Pi is adjusted if it is a forwarding reference and Ai
1311 // is an lvalue reference, in
1312 // which case the type of Pi is changed to be the template parameter
1313 // type (i.e., T&& is changed to simply T). [ Note: As a result, when
1314 // Pi is T&& and Ai is X&, the adjusted Pi will be T, causing T to be
1315 // deduced as X&. - end note ]
1316 TDF &= ~TDF_TopLevelParameterTypeList;
1317 if (isForwardingReference(Param, 0) && Arg->isLValueReferenceType())
1318 Param = Param->getPointeeType();
1322 // C++ [temp.deduct.type]p9:
1323 // A template type argument T, a template template argument TT or a
1324 // template non-type argument i can be deduced if P and A have one of
1325 // the following forms:
1329 if (const TemplateTypeParmType *TemplateTypeParm
1330 = Param->getAs<TemplateTypeParmType>()) {
1331 // Just skip any attempts to deduce from a placeholder type or a parameter
1332 // at a different depth.
1333 if (Arg->isPlaceholderType() ||
1334 Info.getDeducedDepth() != TemplateTypeParm->getDepth())
1335 return Sema::TDK_Success;
1337 unsigned Index = TemplateTypeParm->getIndex();
1338 bool RecanonicalizeArg = false;
1340 // If the argument type is an array type, move the qualifiers up to the
1341 // top level, so they can be matched with the qualifiers on the parameter.
1342 if (isa<ArrayType>(Arg)) {
1344 Arg = S.Context.getUnqualifiedArrayType(Arg, Quals);
1346 Arg = S.Context.getQualifiedType(Arg, Quals);
1347 RecanonicalizeArg = true;
1351 // The argument type can not be less qualified than the parameter
1353 if (!(TDF & TDF_IgnoreQualifiers) &&
1354 hasInconsistentOrSupersetQualifiersOf(Param, Arg)) {
1355 Info.Param = cast<TemplateTypeParmDecl>(TemplateParams->getParam(Index));
1356 Info.FirstArg = TemplateArgument(Param);
1357 Info.SecondArg = TemplateArgument(Arg);
1358 return Sema::TDK_Underqualified;
1361 // Do not match a function type with a cv-qualified type.
1362 // http://www.open-std.org/jtc1/sc22/wg21/docs/cwg_active.html#1584
1363 if (Arg->isFunctionType() && Param.hasQualifiers()) {
1364 return Sema::TDK_NonDeducedMismatch;
1367 assert(TemplateTypeParm->getDepth() == Info.getDeducedDepth() &&
1368 "saw template type parameter with wrong depth");
1369 assert(Arg != S.Context.OverloadTy && "Unresolved overloaded function");
1370 QualType DeducedType = Arg;
1372 // Remove any qualifiers on the parameter from the deduced type.
1373 // We checked the qualifiers for consistency above.
1374 Qualifiers DeducedQs = DeducedType.getQualifiers();
1375 Qualifiers ParamQs = Param.getQualifiers();
1376 DeducedQs.removeCVRQualifiers(ParamQs.getCVRQualifiers());
1377 if (ParamQs.hasObjCGCAttr())
1378 DeducedQs.removeObjCGCAttr();
1379 if (ParamQs.hasAddressSpace())
1380 DeducedQs.removeAddressSpace();
1381 if (ParamQs.hasObjCLifetime())
1382 DeducedQs.removeObjCLifetime();
1385 // If template deduction would produce a lifetime qualifier on a type
1386 // that is not a lifetime type, template argument deduction fails.
1387 if (ParamQs.hasObjCLifetime() && !DeducedType->isObjCLifetimeType() &&
1388 !DeducedType->isDependentType()) {
1389 Info.Param = cast<TemplateTypeParmDecl>(TemplateParams->getParam(Index));
1390 Info.FirstArg = TemplateArgument(Param);
1391 Info.SecondArg = TemplateArgument(Arg);
1392 return Sema::TDK_Underqualified;
1396 // If template deduction would produce an argument type with lifetime type
1397 // but no lifetime qualifier, the __strong lifetime qualifier is inferred.
1398 if (S.getLangOpts().ObjCAutoRefCount &&
1399 DeducedType->isObjCLifetimeType() &&
1400 !DeducedQs.hasObjCLifetime())
1401 DeducedQs.setObjCLifetime(Qualifiers::OCL_Strong);
1403 DeducedType = S.Context.getQualifiedType(DeducedType.getUnqualifiedType(),
1406 if (RecanonicalizeArg)
1407 DeducedType = S.Context.getCanonicalType(DeducedType);
1409 DeducedTemplateArgument NewDeduced(DeducedType, DeducedFromArrayBound);
1410 DeducedTemplateArgument Result = checkDeducedTemplateArguments(S.Context,
1413 if (Result.isNull()) {
1414 Info.Param = cast<TemplateTypeParmDecl>(TemplateParams->getParam(Index));
1415 Info.FirstArg = Deduced[Index];
1416 Info.SecondArg = NewDeduced;
1417 return Sema::TDK_Inconsistent;
1420 Deduced[Index] = Result;
1421 return Sema::TDK_Success;
1424 // Set up the template argument deduction information for a failure.
1425 Info.FirstArg = TemplateArgument(ParamIn);
1426 Info.SecondArg = TemplateArgument(ArgIn);
1428 // If the parameter is an already-substituted template parameter
1429 // pack, do nothing: we don't know which of its arguments to look
1430 // at, so we have to wait until all of the parameter packs in this
1431 // expansion have arguments.
1432 if (isa<SubstTemplateTypeParmPackType>(Param))
1433 return Sema::TDK_Success;
1435 // Check the cv-qualifiers on the parameter and argument types.
1436 CanQualType CanParam = S.Context.getCanonicalType(Param);
1437 CanQualType CanArg = S.Context.getCanonicalType(Arg);
1438 if (!(TDF & TDF_IgnoreQualifiers)) {
1439 if (TDF & TDF_ParamWithReferenceType) {
1440 if (hasInconsistentOrSupersetQualifiersOf(Param, Arg))
1441 return Sema::TDK_NonDeducedMismatch;
1442 } else if (TDF & TDF_ArgWithReferenceType) {
1443 // C++ [temp.deduct.conv]p4:
1444 // If the original A is a reference type, A can be more cv-qualified
1445 // than the deduced A
1446 if (!Arg.getQualifiers().compatiblyIncludes(Param.getQualifiers()))
1447 return Sema::TDK_NonDeducedMismatch;
1449 // Strip out all extra qualifiers from the argument to figure out the
1450 // type we're converting to, prior to the qualification conversion.
1452 Arg = S.Context.getUnqualifiedArrayType(Arg, Quals);
1453 Arg = S.Context.getQualifiedType(Arg, Param.getQualifiers());
1454 } else if (!IsPossiblyOpaquelyQualifiedType(Param)) {
1455 if (Param.getCVRQualifiers() != Arg.getCVRQualifiers())
1456 return Sema::TDK_NonDeducedMismatch;
1459 // If the parameter type is not dependent, there is nothing to deduce.
1460 if (!Param->isDependentType()) {
1461 if (!(TDF & TDF_SkipNonDependent)) {
1463 (TDF & TDF_AllowCompatibleFunctionType)
1464 ? !S.isSameOrCompatibleFunctionType(CanParam, CanArg)
1467 return Sema::TDK_NonDeducedMismatch;
1470 return Sema::TDK_Success;
1472 } else if (!Param->isDependentType()) {
1473 CanQualType ParamUnqualType = CanParam.getUnqualifiedType(),
1474 ArgUnqualType = CanArg.getUnqualifiedType();
1476 (TDF & TDF_AllowCompatibleFunctionType)
1477 ? S.isSameOrCompatibleFunctionType(ParamUnqualType, ArgUnqualType)
1478 : ParamUnqualType == ArgUnqualType;
1480 return Sema::TDK_Success;
1483 switch (Param->getTypeClass()) {
1484 // Non-canonical types cannot appear here.
1485 #define NON_CANONICAL_TYPE(Class, Base) \
1486 case Type::Class: llvm_unreachable("deducing non-canonical type: " #Class);
1487 #define TYPE(Class, Base)
1488 #include "clang/AST/TypeNodes.def"
1490 case Type::TemplateTypeParm:
1491 case Type::SubstTemplateTypeParmPack:
1492 llvm_unreachable("Type nodes handled above");
1494 // These types cannot be dependent, so simply check whether the types are
1497 case Type::VariableArray:
1499 case Type::FunctionNoProto:
1502 case Type::ObjCObject:
1503 case Type::ObjCInterface:
1504 case Type::ObjCObjectPointer:
1505 if (TDF & TDF_SkipNonDependent)
1506 return Sema::TDK_Success;
1508 if (TDF & TDF_IgnoreQualifiers) {
1509 Param = Param.getUnqualifiedType();
1510 Arg = Arg.getUnqualifiedType();
1513 return Param == Arg? Sema::TDK_Success : Sema::TDK_NonDeducedMismatch;
1515 // _Complex T [placeholder extension]
1517 if (const ComplexType *ComplexArg = Arg->getAs<ComplexType>())
1518 return DeduceTemplateArgumentsByTypeMatch(S, TemplateParams,
1519 cast<ComplexType>(Param)->getElementType(),
1520 ComplexArg->getElementType(),
1521 Info, Deduced, TDF);
1523 return Sema::TDK_NonDeducedMismatch;
1525 // _Atomic T [extension]
1527 if (const AtomicType *AtomicArg = Arg->getAs<AtomicType>())
1528 return DeduceTemplateArgumentsByTypeMatch(S, TemplateParams,
1529 cast<AtomicType>(Param)->getValueType(),
1530 AtomicArg->getValueType(),
1531 Info, Deduced, TDF);
1533 return Sema::TDK_NonDeducedMismatch;
1536 case Type::Pointer: {
1537 QualType PointeeType;
1538 if (const PointerType *PointerArg = Arg->getAs<PointerType>()) {
1539 PointeeType = PointerArg->getPointeeType();
1540 } else if (const ObjCObjectPointerType *PointerArg
1541 = Arg->getAs<ObjCObjectPointerType>()) {
1542 PointeeType = PointerArg->getPointeeType();
1544 return Sema::TDK_NonDeducedMismatch;
1547 unsigned SubTDF = TDF & (TDF_IgnoreQualifiers | TDF_DerivedClass);
1548 return DeduceTemplateArgumentsByTypeMatch(S, TemplateParams,
1549 cast<PointerType>(Param)->getPointeeType(),
1551 Info, Deduced, SubTDF);
1555 case Type::LValueReference: {
1556 const LValueReferenceType *ReferenceArg =
1557 Arg->getAs<LValueReferenceType>();
1559 return Sema::TDK_NonDeducedMismatch;
1561 return DeduceTemplateArgumentsByTypeMatch(S, TemplateParams,
1562 cast<LValueReferenceType>(Param)->getPointeeType(),
1563 ReferenceArg->getPointeeType(), Info, Deduced, 0);
1567 case Type::RValueReference: {
1568 const RValueReferenceType *ReferenceArg =
1569 Arg->getAs<RValueReferenceType>();
1571 return Sema::TDK_NonDeducedMismatch;
1573 return DeduceTemplateArgumentsByTypeMatch(S, TemplateParams,
1574 cast<RValueReferenceType>(Param)->getPointeeType(),
1575 ReferenceArg->getPointeeType(),
1579 // T [] (implied, but not stated explicitly)
1580 case Type::IncompleteArray: {
1581 const IncompleteArrayType *IncompleteArrayArg =
1582 S.Context.getAsIncompleteArrayType(Arg);
1583 if (!IncompleteArrayArg)
1584 return Sema::TDK_NonDeducedMismatch;
1586 unsigned SubTDF = TDF & TDF_IgnoreQualifiers;
1587 return DeduceTemplateArgumentsByTypeMatch(S, TemplateParams,
1588 S.Context.getAsIncompleteArrayType(Param)->getElementType(),
1589 IncompleteArrayArg->getElementType(),
1590 Info, Deduced, SubTDF);
1593 // T [integer-constant]
1594 case Type::ConstantArray: {
1595 const ConstantArrayType *ConstantArrayArg =
1596 S.Context.getAsConstantArrayType(Arg);
1597 if (!ConstantArrayArg)
1598 return Sema::TDK_NonDeducedMismatch;
1600 const ConstantArrayType *ConstantArrayParm =
1601 S.Context.getAsConstantArrayType(Param);
1602 if (ConstantArrayArg->getSize() != ConstantArrayParm->getSize())
1603 return Sema::TDK_NonDeducedMismatch;
1605 unsigned SubTDF = TDF & TDF_IgnoreQualifiers;
1606 return DeduceTemplateArgumentsByTypeMatch(S, TemplateParams,
1607 ConstantArrayParm->getElementType(),
1608 ConstantArrayArg->getElementType(),
1609 Info, Deduced, SubTDF);
1613 case Type::DependentSizedArray: {
1614 const ArrayType *ArrayArg = S.Context.getAsArrayType(Arg);
1616 return Sema::TDK_NonDeducedMismatch;
1618 unsigned SubTDF = TDF & TDF_IgnoreQualifiers;
1620 // Check the element type of the arrays
1621 const DependentSizedArrayType *DependentArrayParm
1622 = S.Context.getAsDependentSizedArrayType(Param);
1623 if (Sema::TemplateDeductionResult Result
1624 = DeduceTemplateArgumentsByTypeMatch(S, TemplateParams,
1625 DependentArrayParm->getElementType(),
1626 ArrayArg->getElementType(),
1627 Info, Deduced, SubTDF))
1630 // Determine the array bound is something we can deduce.
1631 NonTypeTemplateParmDecl *NTTP
1632 = getDeducedParameterFromExpr(Info, DependentArrayParm->getSizeExpr());
1634 return Sema::TDK_Success;
1636 // We can perform template argument deduction for the given non-type
1637 // template parameter.
1638 assert(NTTP->getDepth() == Info.getDeducedDepth() &&
1639 "saw non-type template parameter with wrong depth");
1640 if (const ConstantArrayType *ConstantArrayArg
1641 = dyn_cast<ConstantArrayType>(ArrayArg)) {
1642 llvm::APSInt Size(ConstantArrayArg->getSize());
1643 return DeduceNonTypeTemplateArgument(S, TemplateParams, NTTP, Size,
1644 S.Context.getSizeType(),
1645 /*ArrayBound=*/true,
1648 if (const DependentSizedArrayType *DependentArrayArg
1649 = dyn_cast<DependentSizedArrayType>(ArrayArg))
1650 if (DependentArrayArg->getSizeExpr())
1651 return DeduceNonTypeTemplateArgument(S, TemplateParams, NTTP,
1652 DependentArrayArg->getSizeExpr(),
1655 // Incomplete type does not match a dependently-sized array type
1656 return Sema::TDK_NonDeducedMismatch;
1662 case Type::FunctionProto: {
1663 unsigned SubTDF = TDF & TDF_TopLevelParameterTypeList;
1664 const FunctionProtoType *FunctionProtoArg =
1665 dyn_cast<FunctionProtoType>(Arg);
1666 if (!FunctionProtoArg)
1667 return Sema::TDK_NonDeducedMismatch;
1669 const FunctionProtoType *FunctionProtoParam =
1670 cast<FunctionProtoType>(Param);
1672 if (FunctionProtoParam->getTypeQuals()
1673 != FunctionProtoArg->getTypeQuals() ||
1674 FunctionProtoParam->getRefQualifier()
1675 != FunctionProtoArg->getRefQualifier() ||
1676 FunctionProtoParam->isVariadic() != FunctionProtoArg->isVariadic())
1677 return Sema::TDK_NonDeducedMismatch;
1679 // Check return types.
1680 if (auto Result = DeduceTemplateArgumentsByTypeMatch(
1681 S, TemplateParams, FunctionProtoParam->getReturnType(),
1682 FunctionProtoArg->getReturnType(), Info, Deduced, 0))
1685 // Check parameter types.
1686 if (auto Result = DeduceTemplateArguments(
1687 S, TemplateParams, FunctionProtoParam->param_type_begin(),
1688 FunctionProtoParam->getNumParams(),
1689 FunctionProtoArg->param_type_begin(),
1690 FunctionProtoArg->getNumParams(), Info, Deduced, SubTDF))
1693 if (TDF & TDF_AllowCompatibleFunctionType)
1694 return Sema::TDK_Success;
1696 // FIXME: Per core-2016/10/1019 (no corresponding core issue yet), permit
1697 // deducing through the noexcept-specifier if it's part of the canonical
1698 // type. libstdc++ relies on this.
1699 Expr *NoexceptExpr = FunctionProtoParam->getNoexceptExpr();
1700 if (NonTypeTemplateParmDecl *NTTP =
1701 NoexceptExpr ? getDeducedParameterFromExpr(Info, NoexceptExpr)
1703 assert(NTTP->getDepth() == Info.getDeducedDepth() &&
1704 "saw non-type template parameter with wrong depth");
1706 llvm::APSInt Noexcept(1);
1707 switch (FunctionProtoArg->canThrow()) {
1713 // We give E in noexcept(E) the "deduced from array bound" treatment.
1714 // FIXME: Should we?
1715 return DeduceNonTypeTemplateArgument(
1716 S, TemplateParams, NTTP, Noexcept, S.Context.BoolTy,
1717 /*ArrayBound*/true, Info, Deduced);
1720 if (Expr *ArgNoexceptExpr = FunctionProtoArg->getNoexceptExpr())
1721 return DeduceNonTypeTemplateArgument(
1722 S, TemplateParams, NTTP, ArgNoexceptExpr, Info, Deduced);
1723 // Can't deduce anything from throw(T...).
1727 // FIXME: Detect non-deduced exception specification mismatches?
1729 // Careful about [temp.deduct.call] and [temp.deduct.conv], which allow
1730 // top-level differences in noexcept-specifications.
1732 return Sema::TDK_Success;
1735 case Type::InjectedClassName:
1736 // Treat a template's injected-class-name as if the template
1737 // specialization type had been used.
1738 Param = cast<InjectedClassNameType>(Param)
1739 ->getInjectedSpecializationType();
1740 assert(isa<TemplateSpecializationType>(Param) &&
1741 "injected class name is not a template specialization type");
1744 // template-name<T> (where template-name refers to a class template)
1749 case Type::TemplateSpecialization: {
1750 const TemplateSpecializationType *SpecParam =
1751 cast<TemplateSpecializationType>(Param);
1753 // When Arg cannot be a derived class, we can just try to deduce template
1754 // arguments from the template-id.
1755 const RecordType *RecordT = Arg->getAs<RecordType>();
1756 if (!(TDF & TDF_DerivedClass) || !RecordT)
1757 return DeduceTemplateArguments(S, TemplateParams, SpecParam, Arg, Info,
1760 SmallVector<DeducedTemplateArgument, 8> DeducedOrig(Deduced.begin(),
1763 Sema::TemplateDeductionResult Result = DeduceTemplateArguments(
1764 S, TemplateParams, SpecParam, Arg, Info, Deduced);
1766 if (Result == Sema::TDK_Success)
1769 // We cannot inspect base classes as part of deduction when the type
1770 // is incomplete, so either instantiate any templates necessary to
1771 // complete the type, or skip over it if it cannot be completed.
1772 if (!S.isCompleteType(Info.getLocation(), Arg))
1775 // C++14 [temp.deduct.call] p4b3:
1776 // If P is a class and P has the form simple-template-id, then the
1777 // transformed A can be a derived class of the deduced A. Likewise if
1778 // P is a pointer to a class of the form simple-template-id, the
1779 // transformed A can be a pointer to a derived class pointed to by the
1782 // These alternatives are considered only if type deduction would
1783 // otherwise fail. If they yield more than one possible deduced A, the
1784 // type deduction fails.
1786 // Reset the incorrectly deduced argument from above.
1787 Deduced = DeducedOrig;
1789 // Use data recursion to crawl through the list of base classes.
1790 // Visited contains the set of nodes we have already visited, while
1791 // ToVisit is our stack of records that we still need to visit.
1792 llvm::SmallPtrSet<const RecordType *, 8> Visited;
1793 SmallVector<const RecordType *, 8> ToVisit;
1794 ToVisit.push_back(RecordT);
1795 bool Successful = false;
1796 SmallVector<DeducedTemplateArgument, 8> SuccessfulDeduced;
1797 while (!ToVisit.empty()) {
1798 // Retrieve the next class in the inheritance hierarchy.
1799 const RecordType *NextT = ToVisit.pop_back_val();
1801 // If we have already seen this type, skip it.
1802 if (!Visited.insert(NextT).second)
1805 // If this is a base class, try to perform template argument
1806 // deduction from it.
1807 if (NextT != RecordT) {
1808 TemplateDeductionInfo BaseInfo(Info.getLocation());
1809 Sema::TemplateDeductionResult BaseResult =
1810 DeduceTemplateArguments(S, TemplateParams, SpecParam,
1811 QualType(NextT, 0), BaseInfo, Deduced);
1813 // If template argument deduction for this base was successful,
1814 // note that we had some success. Otherwise, ignore any deductions
1815 // from this base class.
1816 if (BaseResult == Sema::TDK_Success) {
1817 // If we've already seen some success, then deduction fails due to
1818 // an ambiguity (temp.deduct.call p5).
1820 return Sema::TDK_MiscellaneousDeductionFailure;
1823 std::swap(SuccessfulDeduced, Deduced);
1825 Info.Param = BaseInfo.Param;
1826 Info.FirstArg = BaseInfo.FirstArg;
1827 Info.SecondArg = BaseInfo.SecondArg;
1830 Deduced = DeducedOrig;
1833 // Visit base classes
1834 CXXRecordDecl *Next = cast<CXXRecordDecl>(NextT->getDecl());
1835 for (const auto &Base : Next->bases()) {
1836 assert(Base.getType()->isRecordType() &&
1837 "Base class that isn't a record?");
1838 ToVisit.push_back(Base.getType()->getAs<RecordType>());
1843 std::swap(SuccessfulDeduced, Deduced);
1844 return Sema::TDK_Success;
1854 // type (type::*)(T)
1859 case Type::MemberPointer: {
1860 const MemberPointerType *MemPtrParam = cast<MemberPointerType>(Param);
1861 const MemberPointerType *MemPtrArg = dyn_cast<MemberPointerType>(Arg);
1863 return Sema::TDK_NonDeducedMismatch;
1865 QualType ParamPointeeType = MemPtrParam->getPointeeType();
1866 if (ParamPointeeType->isFunctionType())
1867 S.adjustMemberFunctionCC(ParamPointeeType, /*IsStatic=*/true,
1868 /*IsCtorOrDtor=*/false, Info.getLocation());
1869 QualType ArgPointeeType = MemPtrArg->getPointeeType();
1870 if (ArgPointeeType->isFunctionType())
1871 S.adjustMemberFunctionCC(ArgPointeeType, /*IsStatic=*/true,
1872 /*IsCtorOrDtor=*/false, Info.getLocation());
1874 if (Sema::TemplateDeductionResult Result
1875 = DeduceTemplateArgumentsByTypeMatch(S, TemplateParams,
1879 TDF & TDF_IgnoreQualifiers))
1882 return DeduceTemplateArgumentsByTypeMatch(S, TemplateParams,
1883 QualType(MemPtrParam->getClass(), 0),
1884 QualType(MemPtrArg->getClass(), 0),
1886 TDF & TDF_IgnoreQualifiers);
1889 // (clang extension)
1894 case Type::BlockPointer: {
1895 const BlockPointerType *BlockPtrParam = cast<BlockPointerType>(Param);
1896 const BlockPointerType *BlockPtrArg = dyn_cast<BlockPointerType>(Arg);
1899 return Sema::TDK_NonDeducedMismatch;
1901 return DeduceTemplateArgumentsByTypeMatch(S, TemplateParams,
1902 BlockPtrParam->getPointeeType(),
1903 BlockPtrArg->getPointeeType(),
1907 // (clang extension)
1909 // T __attribute__(((ext_vector_type(<integral constant>))))
1910 case Type::ExtVector: {
1911 const ExtVectorType *VectorParam = cast<ExtVectorType>(Param);
1912 if (const ExtVectorType *VectorArg = dyn_cast<ExtVectorType>(Arg)) {
1913 // Make sure that the vectors have the same number of elements.
1914 if (VectorParam->getNumElements() != VectorArg->getNumElements())
1915 return Sema::TDK_NonDeducedMismatch;
1917 // Perform deduction on the element types.
1918 return DeduceTemplateArgumentsByTypeMatch(S, TemplateParams,
1919 VectorParam->getElementType(),
1920 VectorArg->getElementType(),
1921 Info, Deduced, TDF);
1924 if (const DependentSizedExtVectorType *VectorArg
1925 = dyn_cast<DependentSizedExtVectorType>(Arg)) {
1926 // We can't check the number of elements, since the argument has a
1927 // dependent number of elements. This can only occur during partial
1930 // Perform deduction on the element types.
1931 return DeduceTemplateArgumentsByTypeMatch(S, TemplateParams,
1932 VectorParam->getElementType(),
1933 VectorArg->getElementType(),
1934 Info, Deduced, TDF);
1937 return Sema::TDK_NonDeducedMismatch;
1940 case Type::DependentVector: {
1941 const auto *VectorParam = cast<DependentVectorType>(Param);
1943 if (const auto *VectorArg = dyn_cast<VectorType>(Arg)) {
1944 // Perform deduction on the element types.
1945 if (Sema::TemplateDeductionResult Result =
1946 DeduceTemplateArgumentsByTypeMatch(
1947 S, TemplateParams, VectorParam->getElementType(),
1948 VectorArg->getElementType(), Info, Deduced, TDF))
1951 // Perform deduction on the vector size, if we can.
1952 NonTypeTemplateParmDecl *NTTP =
1953 getDeducedParameterFromExpr(Info, VectorParam->getSizeExpr());
1955 return Sema::TDK_Success;
1957 llvm::APSInt ArgSize(S.Context.getTypeSize(S.Context.IntTy), false);
1958 ArgSize = VectorArg->getNumElements();
1959 // Note that we use the "array bound" rules here; just like in that
1960 // case, we don't have any particular type for the vector size, but
1961 // we can provide one if necessary.
1962 return DeduceNonTypeTemplateArgument(S, TemplateParams, NTTP, ArgSize,
1963 S.Context.UnsignedIntTy, true,
1967 if (const auto *VectorArg = dyn_cast<DependentVectorType>(Arg)) {
1968 // Perform deduction on the element types.
1969 if (Sema::TemplateDeductionResult Result =
1970 DeduceTemplateArgumentsByTypeMatch(
1971 S, TemplateParams, VectorParam->getElementType(),
1972 VectorArg->getElementType(), Info, Deduced, TDF))
1975 // Perform deduction on the vector size, if we can.
1976 NonTypeTemplateParmDecl *NTTP = getDeducedParameterFromExpr(
1977 Info, VectorParam->getSizeExpr());
1979 return Sema::TDK_Success;
1981 return DeduceNonTypeTemplateArgument(
1982 S, TemplateParams, NTTP, VectorArg->getSizeExpr(), Info, Deduced);
1985 return Sema::TDK_NonDeducedMismatch;
1988 // (clang extension)
1990 // T __attribute__(((ext_vector_type(N))))
1991 case Type::DependentSizedExtVector: {
1992 const DependentSizedExtVectorType *VectorParam
1993 = cast<DependentSizedExtVectorType>(Param);
1995 if (const ExtVectorType *VectorArg = dyn_cast<ExtVectorType>(Arg)) {
1996 // Perform deduction on the element types.
1997 if (Sema::TemplateDeductionResult Result
1998 = DeduceTemplateArgumentsByTypeMatch(S, TemplateParams,
1999 VectorParam->getElementType(),
2000 VectorArg->getElementType(),
2001 Info, Deduced, TDF))
2004 // Perform deduction on the vector size, if we can.
2005 NonTypeTemplateParmDecl *NTTP
2006 = getDeducedParameterFromExpr(Info, VectorParam->getSizeExpr());
2008 return Sema::TDK_Success;
2010 llvm::APSInt ArgSize(S.Context.getTypeSize(S.Context.IntTy), false);
2011 ArgSize = VectorArg->getNumElements();
2012 // Note that we use the "array bound" rules here; just like in that
2013 // case, we don't have any particular type for the vector size, but
2014 // we can provide one if necessary.
2015 return DeduceNonTypeTemplateArgument(S, TemplateParams, NTTP, ArgSize,
2016 S.Context.IntTy, true, Info,
2020 if (const DependentSizedExtVectorType *VectorArg
2021 = dyn_cast<DependentSizedExtVectorType>(Arg)) {
2022 // Perform deduction on the element types.
2023 if (Sema::TemplateDeductionResult Result
2024 = DeduceTemplateArgumentsByTypeMatch(S, TemplateParams,
2025 VectorParam->getElementType(),
2026 VectorArg->getElementType(),
2027 Info, Deduced, TDF))
2030 // Perform deduction on the vector size, if we can.
2031 NonTypeTemplateParmDecl *NTTP
2032 = getDeducedParameterFromExpr(Info, VectorParam->getSizeExpr());
2034 return Sema::TDK_Success;
2036 return DeduceNonTypeTemplateArgument(S, TemplateParams, NTTP,
2037 VectorArg->getSizeExpr(),
2041 return Sema::TDK_NonDeducedMismatch;
2044 // (clang extension)
2046 // T __attribute__(((address_space(N))))
2047 case Type::DependentAddressSpace: {
2048 const DependentAddressSpaceType *AddressSpaceParam =
2049 cast<DependentAddressSpaceType>(Param);
2051 if (const DependentAddressSpaceType *AddressSpaceArg =
2052 dyn_cast<DependentAddressSpaceType>(Arg)) {
2053 // Perform deduction on the pointer type.
2054 if (Sema::TemplateDeductionResult Result =
2055 DeduceTemplateArgumentsByTypeMatch(
2056 S, TemplateParams, AddressSpaceParam->getPointeeType(),
2057 AddressSpaceArg->getPointeeType(), Info, Deduced, TDF))
2060 // Perform deduction on the address space, if we can.
2061 NonTypeTemplateParmDecl *NTTP = getDeducedParameterFromExpr(
2062 Info, AddressSpaceParam->getAddrSpaceExpr());
2064 return Sema::TDK_Success;
2066 return DeduceNonTypeTemplateArgument(
2067 S, TemplateParams, NTTP, AddressSpaceArg->getAddrSpaceExpr(), Info,
2071 if (isTargetAddressSpace(Arg.getAddressSpace())) {
2072 llvm::APSInt ArgAddressSpace(S.Context.getTypeSize(S.Context.IntTy),
2074 ArgAddressSpace = toTargetAddressSpace(Arg.getAddressSpace());
2076 // Perform deduction on the pointer types.
2077 if (Sema::TemplateDeductionResult Result =
2078 DeduceTemplateArgumentsByTypeMatch(
2079 S, TemplateParams, AddressSpaceParam->getPointeeType(),
2080 S.Context.removeAddrSpaceQualType(Arg), Info, Deduced, TDF))
2083 // Perform deduction on the address space, if we can.
2084 NonTypeTemplateParmDecl *NTTP = getDeducedParameterFromExpr(
2085 Info, AddressSpaceParam->getAddrSpaceExpr());
2087 return Sema::TDK_Success;
2089 return DeduceNonTypeTemplateArgument(S, TemplateParams, NTTP,
2090 ArgAddressSpace, S.Context.IntTy,
2091 true, Info, Deduced);
2094 return Sema::TDK_NonDeducedMismatch;
2097 case Type::TypeOfExpr:
2099 case Type::DependentName:
2100 case Type::UnresolvedUsing:
2101 case Type::Decltype:
2102 case Type::UnaryTransform:
2104 case Type::DeducedTemplateSpecialization:
2105 case Type::DependentTemplateSpecialization:
2106 case Type::PackExpansion:
2108 // No template argument deduction for these types
2109 return Sema::TDK_Success;
2112 llvm_unreachable("Invalid Type Class!");
2115 static Sema::TemplateDeductionResult
2116 DeduceTemplateArguments(Sema &S,
2117 TemplateParameterList *TemplateParams,
2118 const TemplateArgument &Param,
2119 TemplateArgument Arg,
2120 TemplateDeductionInfo &Info,
2121 SmallVectorImpl<DeducedTemplateArgument> &Deduced) {
2122 // If the template argument is a pack expansion, perform template argument
2123 // deduction against the pattern of that expansion. This only occurs during
2124 // partial ordering.
2125 if (Arg.isPackExpansion())
2126 Arg = Arg.getPackExpansionPattern();
2128 switch (Param.getKind()) {
2129 case TemplateArgument::Null:
2130 llvm_unreachable("Null template argument in parameter list");
2132 case TemplateArgument::Type:
2133 if (Arg.getKind() == TemplateArgument::Type)
2134 return DeduceTemplateArgumentsByTypeMatch(S, TemplateParams,
2138 Info.FirstArg = Param;
2139 Info.SecondArg = Arg;
2140 return Sema::TDK_NonDeducedMismatch;
2142 case TemplateArgument::Template:
2143 if (Arg.getKind() == TemplateArgument::Template)
2144 return DeduceTemplateArguments(S, TemplateParams,
2145 Param.getAsTemplate(),
2146 Arg.getAsTemplate(), Info, Deduced);
2147 Info.FirstArg = Param;
2148 Info.SecondArg = Arg;
2149 return Sema::TDK_NonDeducedMismatch;
2151 case TemplateArgument::TemplateExpansion:
2152 llvm_unreachable("caller should handle pack expansions");
2154 case TemplateArgument::Declaration:
2155 if (Arg.getKind() == TemplateArgument::Declaration &&
2156 isSameDeclaration(Param.getAsDecl(), Arg.getAsDecl()))
2157 return Sema::TDK_Success;
2159 Info.FirstArg = Param;
2160 Info.SecondArg = Arg;
2161 return Sema::TDK_NonDeducedMismatch;
2163 case TemplateArgument::NullPtr:
2164 if (Arg.getKind() == TemplateArgument::NullPtr &&
2165 S.Context.hasSameType(Param.getNullPtrType(), Arg.getNullPtrType()))
2166 return Sema::TDK_Success;
2168 Info.FirstArg = Param;
2169 Info.SecondArg = Arg;
2170 return Sema::TDK_NonDeducedMismatch;
2172 case TemplateArgument::Integral:
2173 if (Arg.getKind() == TemplateArgument::Integral) {
2174 if (hasSameExtendedValue(Param.getAsIntegral(), Arg.getAsIntegral()))
2175 return Sema::TDK_Success;
2177 Info.FirstArg = Param;
2178 Info.SecondArg = Arg;
2179 return Sema::TDK_NonDeducedMismatch;
2182 if (Arg.getKind() == TemplateArgument::Expression) {
2183 Info.FirstArg = Param;
2184 Info.SecondArg = Arg;
2185 return Sema::TDK_NonDeducedMismatch;
2188 Info.FirstArg = Param;
2189 Info.SecondArg = Arg;
2190 return Sema::TDK_NonDeducedMismatch;
2192 case TemplateArgument::Expression:
2193 if (NonTypeTemplateParmDecl *NTTP
2194 = getDeducedParameterFromExpr(Info, Param.getAsExpr())) {
2195 if (Arg.getKind() == TemplateArgument::Integral)
2196 return DeduceNonTypeTemplateArgument(S, TemplateParams, NTTP,
2197 Arg.getAsIntegral(),
2198 Arg.getIntegralType(),
2199 /*ArrayBound=*/false,
2201 if (Arg.getKind() == TemplateArgument::NullPtr)
2202 return DeduceNullPtrTemplateArgument(S, TemplateParams, NTTP,
2203 Arg.getNullPtrType(),
2205 if (Arg.getKind() == TemplateArgument::Expression)
2206 return DeduceNonTypeTemplateArgument(S, TemplateParams, NTTP,
2207 Arg.getAsExpr(), Info, Deduced);
2208 if (Arg.getKind() == TemplateArgument::Declaration)
2209 return DeduceNonTypeTemplateArgument(S, TemplateParams, NTTP,
2211 Arg.getParamTypeForDecl(),
2214 Info.FirstArg = Param;
2215 Info.SecondArg = Arg;
2216 return Sema::TDK_NonDeducedMismatch;
2219 // Can't deduce anything, but that's okay.
2220 return Sema::TDK_Success;
2222 case TemplateArgument::Pack:
2223 llvm_unreachable("Argument packs should be expanded by the caller!");
2226 llvm_unreachable("Invalid TemplateArgument Kind!");
2229 /// Determine whether there is a template argument to be used for
2232 /// This routine "expands" argument packs in-place, overriding its input
2233 /// parameters so that \c Args[ArgIdx] will be the available template argument.
2235 /// \returns true if there is another template argument (which will be at
2236 /// \c Args[ArgIdx]), false otherwise.
2237 static bool hasTemplateArgumentForDeduction(ArrayRef<TemplateArgument> &Args,
2239 if (ArgIdx == Args.size())
2242 const TemplateArgument &Arg = Args[ArgIdx];
2243 if (Arg.getKind() != TemplateArgument::Pack)
2246 assert(ArgIdx == Args.size() - 1 && "Pack not at the end of argument list?");
2247 Args = Arg.pack_elements();
2249 return ArgIdx < Args.size();
2252 /// Determine whether the given set of template arguments has a pack
2253 /// expansion that is not the last template argument.
2254 static bool hasPackExpansionBeforeEnd(ArrayRef<TemplateArgument> Args) {
2255 bool FoundPackExpansion = false;
2256 for (const auto &A : Args) {
2257 if (FoundPackExpansion)
2260 if (A.getKind() == TemplateArgument::Pack)
2261 return hasPackExpansionBeforeEnd(A.pack_elements());
2263 // FIXME: If this is a fixed-arity pack expansion from an outer level of
2264 // templates, it should not be treated as a pack expansion.
2265 if (A.isPackExpansion())
2266 FoundPackExpansion = true;
2272 static Sema::TemplateDeductionResult
2273 DeduceTemplateArguments(Sema &S, TemplateParameterList *TemplateParams,
2274 ArrayRef<TemplateArgument> Params,
2275 ArrayRef<TemplateArgument> Args,
2276 TemplateDeductionInfo &Info,
2277 SmallVectorImpl<DeducedTemplateArgument> &Deduced,
2278 bool NumberOfArgumentsMustMatch) {
2279 // C++0x [temp.deduct.type]p9:
2280 // If the template argument list of P contains a pack expansion that is not
2281 // the last template argument, the entire template argument list is a
2282 // non-deduced context.
2283 if (hasPackExpansionBeforeEnd(Params))
2284 return Sema::TDK_Success;
2286 // C++0x [temp.deduct.type]p9:
2287 // If P has a form that contains <T> or <i>, then each argument Pi of the
2288 // respective template argument list P is compared with the corresponding
2289 // argument Ai of the corresponding template argument list of A.
2290 unsigned ArgIdx = 0, ParamIdx = 0;
2291 for (; hasTemplateArgumentForDeduction(Params, ParamIdx); ++ParamIdx) {
2292 if (!Params[ParamIdx].isPackExpansion()) {
2293 // The simple case: deduce template arguments by matching Pi and Ai.
2295 // Check whether we have enough arguments.
2296 if (!hasTemplateArgumentForDeduction(Args, ArgIdx))
2297 return NumberOfArgumentsMustMatch
2298 ? Sema::TDK_MiscellaneousDeductionFailure
2299 : Sema::TDK_Success;
2301 // C++1z [temp.deduct.type]p9:
2302 // During partial ordering, if Ai was originally a pack expansion [and]
2303 // Pi is not a pack expansion, template argument deduction fails.
2304 if (Args[ArgIdx].isPackExpansion())
2305 return Sema::TDK_MiscellaneousDeductionFailure;
2307 // Perform deduction for this Pi/Ai pair.
2308 if (Sema::TemplateDeductionResult Result
2309 = DeduceTemplateArguments(S, TemplateParams,
2310 Params[ParamIdx], Args[ArgIdx],
2314 // Move to the next argument.
2319 // The parameter is a pack expansion.
2321 // C++0x [temp.deduct.type]p9:
2322 // If Pi is a pack expansion, then the pattern of Pi is compared with
2323 // each remaining argument in the template argument list of A. Each
2324 // comparison deduces template arguments for subsequent positions in the
2325 // template parameter packs expanded by Pi.
2326 TemplateArgument Pattern = Params[ParamIdx].getPackExpansionPattern();
2328 // Prepare to deduce the packs within the pattern.
2329 PackDeductionScope PackScope(S, TemplateParams, Deduced, Info, Pattern);
2331 // Keep track of the deduced template arguments for each parameter pack
2332 // expanded by this pack expansion (the outer index) and for each
2333 // template argument (the inner SmallVectors).
2334 for (; hasTemplateArgumentForDeduction(Args, ArgIdx) &&
2335 PackScope.hasNextElement();
2337 // Deduce template arguments from the pattern.
2338 if (Sema::TemplateDeductionResult Result
2339 = DeduceTemplateArguments(S, TemplateParams, Pattern, Args[ArgIdx],
2343 PackScope.nextPackElement();
2346 // Build argument packs for each of the parameter packs expanded by this
2348 if (auto Result = PackScope.finish())
2352 return Sema::TDK_Success;
2355 static Sema::TemplateDeductionResult
2356 DeduceTemplateArguments(Sema &S,
2357 TemplateParameterList *TemplateParams,
2358 const TemplateArgumentList &ParamList,
2359 const TemplateArgumentList &ArgList,
2360 TemplateDeductionInfo &Info,
2361 SmallVectorImpl<DeducedTemplateArgument> &Deduced) {
2362 return DeduceTemplateArguments(S, TemplateParams, ParamList.asArray(),
2363 ArgList.asArray(), Info, Deduced,
2364 /*NumberOfArgumentsMustMatch*/false);
2367 /// Determine whether two template arguments are the same.
2368 static bool isSameTemplateArg(ASTContext &Context,
2370 const TemplateArgument &Y,
2371 bool PackExpansionMatchesPack = false) {
2372 // If we're checking deduced arguments (X) against original arguments (Y),
2373 // we will have flattened packs to non-expansions in X.
2374 if (PackExpansionMatchesPack && X.isPackExpansion() && !Y.isPackExpansion())
2375 X = X.getPackExpansionPattern();
2377 if (X.getKind() != Y.getKind())
2380 switch (X.getKind()) {
2381 case TemplateArgument::Null:
2382 llvm_unreachable("Comparing NULL template argument");
2384 case TemplateArgument::Type:
2385 return Context.getCanonicalType(X.getAsType()) ==
2386 Context.getCanonicalType(Y.getAsType());
2388 case TemplateArgument::Declaration:
2389 return isSameDeclaration(X.getAsDecl(), Y.getAsDecl());
2391 case TemplateArgument::NullPtr:
2392 return Context.hasSameType(X.getNullPtrType(), Y.getNullPtrType());
2394 case TemplateArgument::Template:
2395 case TemplateArgument::TemplateExpansion:
2396 return Context.getCanonicalTemplateName(
2397 X.getAsTemplateOrTemplatePattern()).getAsVoidPointer() ==
2398 Context.getCanonicalTemplateName(
2399 Y.getAsTemplateOrTemplatePattern()).getAsVoidPointer();
2401 case TemplateArgument::Integral:
2402 return hasSameExtendedValue(X.getAsIntegral(), Y.getAsIntegral());
2404 case TemplateArgument::Expression: {
2405 llvm::FoldingSetNodeID XID, YID;
2406 X.getAsExpr()->Profile(XID, Context, true);
2407 Y.getAsExpr()->Profile(YID, Context, true);
2411 case TemplateArgument::Pack:
2412 if (X.pack_size() != Y.pack_size())
2415 for (TemplateArgument::pack_iterator XP = X.pack_begin(),
2416 XPEnd = X.pack_end(),
2417 YP = Y.pack_begin();
2418 XP != XPEnd; ++XP, ++YP)
2419 if (!isSameTemplateArg(Context, *XP, *YP, PackExpansionMatchesPack))
2425 llvm_unreachable("Invalid TemplateArgument Kind!");
2428 /// Allocate a TemplateArgumentLoc where all locations have
2429 /// been initialized to the given location.
2431 /// \param Arg The template argument we are producing template argument
2432 /// location information for.
2434 /// \param NTTPType For a declaration template argument, the type of
2435 /// the non-type template parameter that corresponds to this template
2436 /// argument. Can be null if no type sugar is available to add to the
2437 /// type from the template argument.
2439 /// \param Loc The source location to use for the resulting template
2442 Sema::getTrivialTemplateArgumentLoc(const TemplateArgument &Arg,
2443 QualType NTTPType, SourceLocation Loc) {
2444 switch (Arg.getKind()) {
2445 case TemplateArgument::Null:
2446 llvm_unreachable("Can't get a NULL template argument here");
2448 case TemplateArgument::Type:
2449 return TemplateArgumentLoc(
2450 Arg, Context.getTrivialTypeSourceInfo(Arg.getAsType(), Loc));
2452 case TemplateArgument::Declaration: {
2453 if (NTTPType.isNull())
2454 NTTPType = Arg.getParamTypeForDecl();
2455 Expr *E = BuildExpressionFromDeclTemplateArgument(Arg, NTTPType, Loc)
2457 return TemplateArgumentLoc(TemplateArgument(E), E);
2460 case TemplateArgument::NullPtr: {
2461 if (NTTPType.isNull())
2462 NTTPType = Arg.getNullPtrType();
2463 Expr *E = BuildExpressionFromDeclTemplateArgument(Arg, NTTPType, Loc)
2465 return TemplateArgumentLoc(TemplateArgument(NTTPType, /*isNullPtr*/true),
2469 case TemplateArgument::Integral: {
2471 BuildExpressionFromIntegralTemplateArgument(Arg, Loc).getAs<Expr>();
2472 return TemplateArgumentLoc(TemplateArgument(E), E);
2475 case TemplateArgument::Template:
2476 case TemplateArgument::TemplateExpansion: {
2477 NestedNameSpecifierLocBuilder Builder;
2478 TemplateName Template = Arg.getAsTemplate();
2479 if (DependentTemplateName *DTN = Template.getAsDependentTemplateName())
2480 Builder.MakeTrivial(Context, DTN->getQualifier(), Loc);
2481 else if (QualifiedTemplateName *QTN =
2482 Template.getAsQualifiedTemplateName())
2483 Builder.MakeTrivial(Context, QTN->getQualifier(), Loc);
2485 if (Arg.getKind() == TemplateArgument::Template)
2486 return TemplateArgumentLoc(Arg, Builder.getWithLocInContext(Context),
2489 return TemplateArgumentLoc(Arg, Builder.getWithLocInContext(Context),
2493 case TemplateArgument::Expression:
2494 return TemplateArgumentLoc(Arg, Arg.getAsExpr());
2496 case TemplateArgument::Pack:
2497 return TemplateArgumentLoc(Arg, TemplateArgumentLocInfo());
2500 llvm_unreachable("Invalid TemplateArgument Kind!");
2503 /// Convert the given deduced template argument and add it to the set of
2504 /// fully-converted template arguments.
2506 ConvertDeducedTemplateArgument(Sema &S, NamedDecl *Param,
2507 DeducedTemplateArgument Arg,
2508 NamedDecl *Template,
2509 TemplateDeductionInfo &Info,
2511 SmallVectorImpl<TemplateArgument> &Output) {
2512 auto ConvertArg = [&](DeducedTemplateArgument Arg,
2513 unsigned ArgumentPackIndex) {
2514 // Convert the deduced template argument into a template
2515 // argument that we can check, almost as if the user had written
2516 // the template argument explicitly.
2517 TemplateArgumentLoc ArgLoc =
2518 S.getTrivialTemplateArgumentLoc(Arg, QualType(), Info.getLocation());
2520 // Check the template argument, converting it as necessary.
2521 return S.CheckTemplateArgument(
2522 Param, ArgLoc, Template, Template->getLocation(),
2523 Template->getSourceRange().getEnd(), ArgumentPackIndex, Output,
2525 ? (Arg.wasDeducedFromArrayBound() ? Sema::CTAK_DeducedFromArrayBound
2526 : Sema::CTAK_Deduced)
2527 : Sema::CTAK_Specified);
2530 if (Arg.getKind() == TemplateArgument::Pack) {
2531 // This is a template argument pack, so check each of its arguments against
2532 // the template parameter.
2533 SmallVector<TemplateArgument, 2> PackedArgsBuilder;
2534 for (const auto &P : Arg.pack_elements()) {
2535 // When converting the deduced template argument, append it to the
2536 // general output list. We need to do this so that the template argument
2537 // checking logic has all of the prior template arguments available.
2538 DeducedTemplateArgument InnerArg(P);
2539 InnerArg.setDeducedFromArrayBound(Arg.wasDeducedFromArrayBound());
2540 assert(InnerArg.getKind() != TemplateArgument::Pack &&
2541 "deduced nested pack");
2543 // We deduced arguments for some elements of this pack, but not for
2544 // all of them. This happens if we get a conditionally-non-deduced
2545 // context in a pack expansion (such as an overload set in one of the
2547 S.Diag(Param->getLocation(),
2548 diag::err_template_arg_deduced_incomplete_pack)
2552 if (ConvertArg(InnerArg, PackedArgsBuilder.size()))
2555 // Move the converted template argument into our argument pack.
2556 PackedArgsBuilder.push_back(Output.pop_back_val());
2559 // If the pack is empty, we still need to substitute into the parameter
2560 // itself, in case that substitution fails.
2561 if (PackedArgsBuilder.empty()) {
2562 LocalInstantiationScope Scope(S);
2563 TemplateArgumentList TemplateArgs(TemplateArgumentList::OnStack, Output);
2564 MultiLevelTemplateArgumentList Args(TemplateArgs);
2566 if (auto *NTTP = dyn_cast<NonTypeTemplateParmDecl>(Param)) {
2567 Sema::InstantiatingTemplate Inst(S, Template->getLocation(), Template,
2569 Template->getSourceRange());
2570 if (Inst.isInvalid() ||
2571 S.SubstType(NTTP->getType(), Args, NTTP->getLocation(),
2572 NTTP->getDeclName()).isNull())
2574 } else if (auto *TTP = dyn_cast<TemplateTemplateParmDecl>(Param)) {
2575 Sema::InstantiatingTemplate Inst(S, Template->getLocation(), Template,
2577 Template->getSourceRange());
2578 if (Inst.isInvalid() || !S.SubstDecl(TTP, S.CurContext, Args))
2581 // For type parameters, no substitution is ever required.
2584 // Create the resulting argument pack.
2586 TemplateArgument::CreatePackCopy(S.Context, PackedArgsBuilder));
2590 return ConvertArg(Arg, 0);
2593 // FIXME: This should not be a template, but
2594 // ClassTemplatePartialSpecializationDecl sadly does not derive from
2596 template<typename TemplateDeclT>
2597 static Sema::TemplateDeductionResult ConvertDeducedTemplateArguments(
2598 Sema &S, TemplateDeclT *Template, bool IsDeduced,
2599 SmallVectorImpl<DeducedTemplateArgument> &Deduced,
2600 TemplateDeductionInfo &Info, SmallVectorImpl<TemplateArgument> &Builder,
2601 LocalInstantiationScope *CurrentInstantiationScope = nullptr,
2602 unsigned NumAlreadyConverted = 0, bool PartialOverloading = false) {
2603 TemplateParameterList *TemplateParams = Template->getTemplateParameters();
2605 for (unsigned I = 0, N = TemplateParams->size(); I != N; ++I) {
2606 NamedDecl *Param = TemplateParams->getParam(I);
2608 // C++0x [temp.arg.explicit]p3:
2609 // A trailing template parameter pack (14.5.3) not otherwise deduced will
2610 // be deduced to an empty sequence of template arguments.
2611 // FIXME: Where did the word "trailing" come from?
2612 if (Deduced[I].isNull() && Param->isTemplateParameterPack()) {
2613 if (auto Result = PackDeductionScope(S, TemplateParams, Deduced, Info, I)
2614 .finish(/*TreatNoDeductionsAsNonDeduced*/false))
2618 if (!Deduced[I].isNull()) {
2619 if (I < NumAlreadyConverted) {
2620 // We may have had explicitly-specified template arguments for a
2621 // template parameter pack (that may or may not have been extended
2622 // via additional deduced arguments).
2623 if (Param->isParameterPack() && CurrentInstantiationScope &&
2624 CurrentInstantiationScope->getPartiallySubstitutedPack() == Param) {
2625 // Forget the partially-substituted pack; its substitution is now
2627 CurrentInstantiationScope->ResetPartiallySubstitutedPack();
2628 // We still need to check the argument in case it was extended by
2631 // We have already fully type-checked and converted this
2632 // argument, because it was explicitly-specified. Just record the
2633 // presence of this argument.
2634 Builder.push_back(Deduced[I]);
2639 // We may have deduced this argument, so it still needs to be
2640 // checked and converted.
2641 if (ConvertDeducedTemplateArgument(S, Param, Deduced[I], Template, Info,
2642 IsDeduced, Builder)) {
2643 Info.Param = makeTemplateParameter(Param);
2644 // FIXME: These template arguments are temporary. Free them!
2645 Info.reset(TemplateArgumentList::CreateCopy(S.Context, Builder));
2646 return Sema::TDK_SubstitutionFailure;
2652 // Substitute into the default template argument, if available.
2653 bool HasDefaultArg = false;
2654 TemplateDecl *TD = dyn_cast<TemplateDecl>(Template);
2656 assert(isa<ClassTemplatePartialSpecializationDecl>(Template) ||
2657 isa<VarTemplatePartialSpecializationDecl>(Template));
2658 return Sema::TDK_Incomplete;
2661 TemplateArgumentLoc DefArg = S.SubstDefaultTemplateArgumentIfAvailable(
2662 TD, TD->getLocation(), TD->getSourceRange().getEnd(), Param, Builder,
2665 // If there was no default argument, deduction is incomplete.
2666 if (DefArg.getArgument().isNull()) {
2667 Info.Param = makeTemplateParameter(
2668 const_cast<NamedDecl *>(TemplateParams->getParam(I)));
2669 Info.reset(TemplateArgumentList::CreateCopy(S.Context, Builder));
2670 if (PartialOverloading) break;
2672 return HasDefaultArg ? Sema::TDK_SubstitutionFailure
2673 : Sema::TDK_Incomplete;
2676 // Check whether we can actually use the default argument.
2677 if (S.CheckTemplateArgument(Param, DefArg, TD, TD->getLocation(),
2678 TD->getSourceRange().getEnd(), 0, Builder,
2679 Sema::CTAK_Specified)) {
2680 Info.Param = makeTemplateParameter(
2681 const_cast<NamedDecl *>(TemplateParams->getParam(I)));
2682 // FIXME: These template arguments are temporary. Free them!
2683 Info.reset(TemplateArgumentList::CreateCopy(S.Context, Builder));
2684 return Sema::TDK_SubstitutionFailure;
2687 // If we get here, we successfully used the default template argument.
2690 return Sema::TDK_Success;
2693 static DeclContext *getAsDeclContextOrEnclosing(Decl *D) {
2694 if (auto *DC = dyn_cast<DeclContext>(D))
2696 return D->getDeclContext();
2699 template<typename T> struct IsPartialSpecialization {
2700 static constexpr bool value = false;
2703 struct IsPartialSpecialization<ClassTemplatePartialSpecializationDecl> {
2704 static constexpr bool value = true;
2707 struct IsPartialSpecialization<VarTemplatePartialSpecializationDecl> {
2708 static constexpr bool value = true;
2711 /// Complete template argument deduction for a partial specialization.
2712 template <typename T>
2713 static typename std::enable_if<IsPartialSpecialization<T>::value,
2714 Sema::TemplateDeductionResult>::type
2715 FinishTemplateArgumentDeduction(
2716 Sema &S, T *Partial, bool IsPartialOrdering,
2717 const TemplateArgumentList &TemplateArgs,
2718 SmallVectorImpl<DeducedTemplateArgument> &Deduced,
2719 TemplateDeductionInfo &Info) {
2720 // Unevaluated SFINAE context.
2721 EnterExpressionEvaluationContext Unevaluated(
2722 S, Sema::ExpressionEvaluationContext::Unevaluated);
2723 Sema::SFINAETrap Trap(S);
2725 Sema::ContextRAII SavedContext(S, getAsDeclContextOrEnclosing(Partial));
2727 // C++ [temp.deduct.type]p2:
2728 // [...] or if any template argument remains neither deduced nor
2729 // explicitly specified, template argument deduction fails.
2730 SmallVector<TemplateArgument, 4> Builder;
2731 if (auto Result = ConvertDeducedTemplateArguments(
2732 S, Partial, IsPartialOrdering, Deduced, Info, Builder))
2735 // Form the template argument list from the deduced template arguments.
2736 TemplateArgumentList *DeducedArgumentList
2737 = TemplateArgumentList::CreateCopy(S.Context, Builder);
2739 Info.reset(DeducedArgumentList);
2741 // Substitute the deduced template arguments into the template
2742 // arguments of the class template partial specialization, and
2743 // verify that the instantiated template arguments are both valid
2744 // and are equivalent to the template arguments originally provided
2745 // to the class template.
2746 LocalInstantiationScope InstScope(S);
2747 auto *Template = Partial->getSpecializedTemplate();
2748 const ASTTemplateArgumentListInfo *PartialTemplArgInfo =
2749 Partial->getTemplateArgsAsWritten();
2750 const TemplateArgumentLoc *PartialTemplateArgs =
2751 PartialTemplArgInfo->getTemplateArgs();
2753 TemplateArgumentListInfo InstArgs(PartialTemplArgInfo->LAngleLoc,
2754 PartialTemplArgInfo->RAngleLoc);
2756 if (S.Subst(PartialTemplateArgs, PartialTemplArgInfo->NumTemplateArgs,
2757 InstArgs, MultiLevelTemplateArgumentList(*DeducedArgumentList))) {
2758 unsigned ArgIdx = InstArgs.size(), ParamIdx = ArgIdx;
2759 if (ParamIdx >= Partial->getTemplateParameters()->size())
2760 ParamIdx = Partial->getTemplateParameters()->size() - 1;
2762 Decl *Param = const_cast<NamedDecl *>(
2763 Partial->getTemplateParameters()->getParam(ParamIdx));
2764 Info.Param = makeTemplateParameter(Param);
2765 Info.FirstArg = PartialTemplateArgs[ArgIdx].getArgument();
2766 return Sema::TDK_SubstitutionFailure;
2769 SmallVector<TemplateArgument, 4> ConvertedInstArgs;
2770 if (S.CheckTemplateArgumentList(Template, Partial->getLocation(), InstArgs,
2771 false, ConvertedInstArgs))
2772 return Sema::TDK_SubstitutionFailure;
2774 TemplateParameterList *TemplateParams = Template->getTemplateParameters();
2775 for (unsigned I = 0, E = TemplateParams->size(); I != E; ++I) {
2776 TemplateArgument InstArg = ConvertedInstArgs.data()[I];
2777 if (!isSameTemplateArg(S.Context, TemplateArgs[I], InstArg)) {
2778 Info.Param = makeTemplateParameter(TemplateParams->getParam(I));
2779 Info.FirstArg = TemplateArgs[I];
2780 Info.SecondArg = InstArg;
2781 return Sema::TDK_NonDeducedMismatch;
2785 if (Trap.hasErrorOccurred())
2786 return Sema::TDK_SubstitutionFailure;
2788 return Sema::TDK_Success;
2791 /// Complete template argument deduction for a class or variable template,
2792 /// when partial ordering against a partial specialization.
2793 // FIXME: Factor out duplication with partial specialization version above.
2794 static Sema::TemplateDeductionResult FinishTemplateArgumentDeduction(
2795 Sema &S, TemplateDecl *Template, bool PartialOrdering,
2796 const TemplateArgumentList &TemplateArgs,
2797 SmallVectorImpl<DeducedTemplateArgument> &Deduced,
2798 TemplateDeductionInfo &Info) {
2799 // Unevaluated SFINAE context.
2800 EnterExpressionEvaluationContext Unevaluated(
2801 S, Sema::ExpressionEvaluationContext::Unevaluated);
2802 Sema::SFINAETrap Trap(S);
2804 Sema::ContextRAII SavedContext(S, getAsDeclContextOrEnclosing(Template));
2806 // C++ [temp.deduct.type]p2:
2807 // [...] or if any template argument remains neither deduced nor
2808 // explicitly specified, template argument deduction fails.
2809 SmallVector<TemplateArgument, 4> Builder;
2810 if (auto Result = ConvertDeducedTemplateArguments(
2811 S, Template, /*IsDeduced*/PartialOrdering, Deduced, Info, Builder))
2814 // Check that we produced the correct argument list.
2815 TemplateParameterList *TemplateParams = Template->getTemplateParameters();
2816 for (unsigned I = 0, E = TemplateParams->size(); I != E; ++I) {
2817 TemplateArgument InstArg = Builder[I];
2818 if (!isSameTemplateArg(S.Context, TemplateArgs[I], InstArg,
2819 /*PackExpansionMatchesPack*/true)) {
2820 Info.Param = makeTemplateParameter(TemplateParams->getParam(I));
2821 Info.FirstArg = TemplateArgs[I];
2822 Info.SecondArg = InstArg;
2823 return Sema::TDK_NonDeducedMismatch;
2827 if (Trap.hasErrorOccurred())
2828 return Sema::TDK_SubstitutionFailure;
2830 return Sema::TDK_Success;
2834 /// Perform template argument deduction to determine whether
2835 /// the given template arguments match the given class template
2836 /// partial specialization per C++ [temp.class.spec.match].
2837 Sema::TemplateDeductionResult
2838 Sema::DeduceTemplateArguments(ClassTemplatePartialSpecializationDecl *Partial,
2839 const TemplateArgumentList &TemplateArgs,
2840 TemplateDeductionInfo &Info) {
2841 if (Partial->isInvalidDecl())
2844 // C++ [temp.class.spec.match]p2:
2845 // A partial specialization matches a given actual template
2846 // argument list if the template arguments of the partial
2847 // specialization can be deduced from the actual template argument
2850 // Unevaluated SFINAE context.
2851 EnterExpressionEvaluationContext Unevaluated(
2852 *this, Sema::ExpressionEvaluationContext::Unevaluated);
2853 SFINAETrap Trap(*this);
2855 SmallVector<DeducedTemplateArgument, 4> Deduced;
2856 Deduced.resize(Partial->getTemplateParameters()->size());
2857 if (TemplateDeductionResult Result
2858 = ::DeduceTemplateArguments(*this,
2859 Partial->getTemplateParameters(),
2860 Partial->getTemplateArgs(),
2861 TemplateArgs, Info, Deduced))
2864 SmallVector<TemplateArgument, 4> DeducedArgs(Deduced.begin(), Deduced.end());
2865 InstantiatingTemplate Inst(*this, Info.getLocation(), Partial, DeducedArgs,
2867 if (Inst.isInvalid())
2868 return TDK_InstantiationDepth;
2870 if (Trap.hasErrorOccurred())
2871 return Sema::TDK_SubstitutionFailure;
2873 return ::FinishTemplateArgumentDeduction(
2874 *this, Partial, /*PartialOrdering=*/false, TemplateArgs, Deduced, Info);
2877 /// Perform template argument deduction to determine whether
2878 /// the given template arguments match the given variable template
2879 /// partial specialization per C++ [temp.class.spec.match].
2880 Sema::TemplateDeductionResult
2881 Sema::DeduceTemplateArguments(VarTemplatePartialSpecializationDecl *Partial,
2882 const TemplateArgumentList &TemplateArgs,
2883 TemplateDeductionInfo &Info) {
2884 if (Partial->isInvalidDecl())
2887 // C++ [temp.class.spec.match]p2:
2888 // A partial specialization matches a given actual template
2889 // argument list if the template arguments of the partial
2890 // specialization can be deduced from the actual template argument
2893 // Unevaluated SFINAE context.
2894 EnterExpressionEvaluationContext Unevaluated(
2895 *this, Sema::ExpressionEvaluationContext::Unevaluated);
2896 SFINAETrap Trap(*this);
2898 SmallVector<DeducedTemplateArgument, 4> Deduced;
2899 Deduced.resize(Partial->getTemplateParameters()->size());
2900 if (TemplateDeductionResult Result = ::DeduceTemplateArguments(
2901 *this, Partial->getTemplateParameters(), Partial->getTemplateArgs(),
2902 TemplateArgs, Info, Deduced))
2905 SmallVector<TemplateArgument, 4> DeducedArgs(Deduced.begin(), Deduced.end());
2906 InstantiatingTemplate Inst(*this, Info.getLocation(), Partial, DeducedArgs,
2908 if (Inst.isInvalid())
2909 return TDK_InstantiationDepth;
2911 if (Trap.hasErrorOccurred())
2912 return Sema::TDK_SubstitutionFailure;
2914 return ::FinishTemplateArgumentDeduction(
2915 *this, Partial, /*PartialOrdering=*/false, TemplateArgs, Deduced, Info);
2918 /// Determine whether the given type T is a simple-template-id type.
2919 static bool isSimpleTemplateIdType(QualType T) {
2920 if (const TemplateSpecializationType *Spec
2921 = T->getAs<TemplateSpecializationType>())
2922 return Spec->getTemplateName().getAsTemplateDecl() != nullptr;
2924 // C++17 [temp.local]p2:
2925 // the injected-class-name [...] is equivalent to the template-name followed
2926 // by the template-arguments of the class template specialization or partial
2927 // specialization enclosed in <>
2928 // ... which means it's equivalent to a simple-template-id.
2930 // This only arises during class template argument deduction for a copy
2931 // deduction candidate, where it permits slicing.
2932 if (T->getAs<InjectedClassNameType>())
2938 /// Substitute the explicitly-provided template arguments into the
2939 /// given function template according to C++ [temp.arg.explicit].
2941 /// \param FunctionTemplate the function template into which the explicit
2942 /// template arguments will be substituted.
2944 /// \param ExplicitTemplateArgs the explicitly-specified template
2947 /// \param Deduced the deduced template arguments, which will be populated
2948 /// with the converted and checked explicit template arguments.
2950 /// \param ParamTypes will be populated with the instantiated function
2953 /// \param FunctionType if non-NULL, the result type of the function template
2954 /// will also be instantiated and the pointed-to value will be updated with
2955 /// the instantiated function type.
2957 /// \param Info if substitution fails for any reason, this object will be
2958 /// populated with more information about the failure.
2960 /// \returns TDK_Success if substitution was successful, or some failure
2962 Sema::TemplateDeductionResult
2963 Sema::SubstituteExplicitTemplateArguments(
2964 FunctionTemplateDecl *FunctionTemplate,
2965 TemplateArgumentListInfo &ExplicitTemplateArgs,
2966 SmallVectorImpl<DeducedTemplateArgument> &Deduced,
2967 SmallVectorImpl<QualType> &ParamTypes,
2968 QualType *FunctionType,
2969 TemplateDeductionInfo &Info) {
2970 FunctionDecl *Function = FunctionTemplate->getTemplatedDecl();
2971 TemplateParameterList *TemplateParams
2972 = FunctionTemplate->getTemplateParameters();
2974 if (ExplicitTemplateArgs.size() == 0) {
2975 // No arguments to substitute; just copy over the parameter types and
2976 // fill in the function type.
2977 for (auto P : Function->parameters())
2978 ParamTypes.push_back(P->getType());
2981 *FunctionType = Function->getType();
2985 // Unevaluated SFINAE context.
2986 EnterExpressionEvaluationContext Unevaluated(
2987 *this, Sema::ExpressionEvaluationContext::Unevaluated);
2988 SFINAETrap Trap(*this);
2990 // C++ [temp.arg.explicit]p3:
2991 // Template arguments that are present shall be specified in the
2992 // declaration order of their corresponding template-parameters. The
2993 // template argument list shall not specify more template-arguments than
2994 // there are corresponding template-parameters.
2995 SmallVector<TemplateArgument, 4> Builder;
2997 // Enter a new template instantiation context where we check the
2998 // explicitly-specified template arguments against this function template,
2999 // and then substitute them into the function parameter types.
3000 SmallVector<TemplateArgument, 4> DeducedArgs;
3001 InstantiatingTemplate Inst(
3002 *this, Info.getLocation(), FunctionTemplate, DeducedArgs,
3003 CodeSynthesisContext::ExplicitTemplateArgumentSubstitution, Info);
3004 if (Inst.isInvalid())
3005 return TDK_InstantiationDepth;
3007 if (CheckTemplateArgumentList(FunctionTemplate, SourceLocation(),
3008 ExplicitTemplateArgs, true, Builder, false) ||
3009 Trap.hasErrorOccurred()) {
3010 unsigned Index = Builder.size();
3011 if (Index >= TemplateParams->size())
3012 return TDK_SubstitutionFailure;
3013 Info.Param = makeTemplateParameter(TemplateParams->getParam(Index));
3014 return TDK_InvalidExplicitArguments;
3017 // Form the template argument list from the explicitly-specified
3018 // template arguments.
3019 TemplateArgumentList *ExplicitArgumentList
3020 = TemplateArgumentList::CreateCopy(Context, Builder);
3021 Info.setExplicitArgs(ExplicitArgumentList);
3023 // Template argument deduction and the final substitution should be
3024 // done in the context of the templated declaration. Explicit
3025 // argument substitution, on the other hand, needs to happen in the
3027 ContextRAII SavedContext(*this, FunctionTemplate->getTemplatedDecl());
3029 // If we deduced template arguments for a template parameter pack,
3030 // note that the template argument pack is partially substituted and record
3031 // the explicit template arguments. They'll be used as part of deduction
3032 // for this template parameter pack.
3033 unsigned PartiallySubstitutedPackIndex = -1u;
3034 if (!Builder.empty()) {
3035 const TemplateArgument &Arg = Builder.back();
3036 if (Arg.getKind() == TemplateArgument::Pack) {
3037 auto *Param = TemplateParams->getParam(Builder.size() - 1);
3038 // If this is a fully-saturated fixed-size pack, it should be
3039 // fully-substituted, not partially-substituted.
3040 Optional<unsigned> Expansions = getExpandedPackSize(Param);
3041 if (!Expansions || Arg.pack_size() < *Expansions) {
3042 PartiallySubstitutedPackIndex = Builder.size() - 1;
3043 CurrentInstantiationScope->SetPartiallySubstitutedPack(
3044 Param, Arg.pack_begin(), Arg.pack_size());
3049 const FunctionProtoType *Proto
3050 = Function->getType()->getAs<FunctionProtoType>();
3051 assert(Proto && "Function template does not have a prototype?");
3053 // Isolate our substituted parameters from our caller.
3054 LocalInstantiationScope InstScope(*this, /*MergeWithOuterScope*/true);
3056 ExtParameterInfoBuilder ExtParamInfos;
3058 // Instantiate the types of each of the function parameters given the
3059 // explicitly-specified template arguments. If the function has a trailing
3060 // return type, substitute it after the arguments to ensure we substitute
3061 // in lexical order.
3062 if (Proto->hasTrailingReturn()) {
3063 if (SubstParmTypes(Function->getLocation(), Function->parameters(),
3064 Proto->getExtParameterInfosOrNull(),
3065 MultiLevelTemplateArgumentList(*ExplicitArgumentList),
3066 ParamTypes, /*params*/ nullptr, ExtParamInfos))
3067 return TDK_SubstitutionFailure;
3070 // Instantiate the return type.
3071 QualType ResultType;
3073 // C++11 [expr.prim.general]p3:
3074 // If a declaration declares a member function or member function
3075 // template of a class X, the expression this is a prvalue of type
3076 // "pointer to cv-qualifier-seq X" between the optional cv-qualifer-seq
3077 // and the end of the function-definition, member-declarator, or
3079 unsigned ThisTypeQuals = 0;
3080 CXXRecordDecl *ThisContext = nullptr;
3081 if (CXXMethodDecl *Method = dyn_cast<CXXMethodDecl>(Function)) {
3082 ThisContext = Method->getParent();
3083 ThisTypeQuals = Method->getTypeQualifiers();
3086 CXXThisScopeRAII ThisScope(*this, ThisContext, ThisTypeQuals,
3087 getLangOpts().CPlusPlus11);
3090 SubstType(Proto->getReturnType(),
3091 MultiLevelTemplateArgumentList(*ExplicitArgumentList),
3092 Function->getTypeSpecStartLoc(), Function->getDeclName());
3093 if (ResultType.isNull() || Trap.hasErrorOccurred())
3094 return TDK_SubstitutionFailure;
3097 // Instantiate the types of each of the function parameters given the
3098 // explicitly-specified template arguments if we didn't do so earlier.
3099 if (!Proto->hasTrailingReturn() &&
3100 SubstParmTypes(Function->getLocation(), Function->parameters(),
3101 Proto->getExtParameterInfosOrNull(),
3102 MultiLevelTemplateArgumentList(*ExplicitArgumentList),
3103 ParamTypes, /*params*/ nullptr, ExtParamInfos))
3104 return TDK_SubstitutionFailure;
3107 auto EPI = Proto->getExtProtoInfo();
3108 EPI.ExtParameterInfos = ExtParamInfos.getPointerOrNull(ParamTypes.size());
3110 // In C++1z onwards, exception specifications are part of the function type,
3111 // so substitution into the type must also substitute into the exception
3113 SmallVector<QualType, 4> ExceptionStorage;
3114 if (getLangOpts().CPlusPlus17 &&
3116 Function->getLocation(), EPI.ExceptionSpec, ExceptionStorage,
3117 MultiLevelTemplateArgumentList(*ExplicitArgumentList)))
3118 return TDK_SubstitutionFailure;
3120 *FunctionType = BuildFunctionType(ResultType, ParamTypes,
3121 Function->getLocation(),
3122 Function->getDeclName(),
3124 if (FunctionType->isNull() || Trap.hasErrorOccurred())
3125 return TDK_SubstitutionFailure;
3128 // C++ [temp.arg.explicit]p2:
3129 // Trailing template arguments that can be deduced (14.8.2) may be
3130 // omitted from the list of explicit template-arguments. If all of the
3131 // template arguments can be deduced, they may all be omitted; in this
3132 // case, the empty template argument list <> itself may also be omitted.
3134 // Take all of the explicitly-specified arguments and put them into
3135 // the set of deduced template arguments. The partially-substituted
3136 // parameter pack, however, will be set to NULL since the deduction
3137 // mechanism handles the partially-substituted argument pack directly.
3138 Deduced.reserve(TemplateParams->size());
3139 for (unsigned I = 0, N = ExplicitArgumentList->size(); I != N; ++I) {
3140 const TemplateArgument &Arg = ExplicitArgumentList->get(I);
3141 if (I == PartiallySubstitutedPackIndex)
3142 Deduced.push_back(DeducedTemplateArgument());
3144 Deduced.push_back(Arg);
3150 /// Check whether the deduced argument type for a call to a function
3151 /// template matches the actual argument type per C++ [temp.deduct.call]p4.
3152 static Sema::TemplateDeductionResult
3153 CheckOriginalCallArgDeduction(Sema &S, TemplateDeductionInfo &Info,
3154 Sema::OriginalCallArg OriginalArg,
3155 QualType DeducedA) {
3156 ASTContext &Context = S.Context;
3158 auto Failed = [&]() -> Sema::TemplateDeductionResult {
3159 Info.FirstArg = TemplateArgument(DeducedA);
3160 Info.SecondArg = TemplateArgument(OriginalArg.OriginalArgType);
3161 Info.CallArgIndex = OriginalArg.ArgIdx;
3162 return OriginalArg.DecomposedParam ? Sema::TDK_DeducedMismatchNested
3163 : Sema::TDK_DeducedMismatch;
3166 QualType A = OriginalArg.OriginalArgType;
3167 QualType OriginalParamType = OriginalArg.OriginalParamType;
3169 // Check for type equality (top-level cv-qualifiers are ignored).
3170 if (Context.hasSameUnqualifiedType(A, DeducedA))
3171 return Sema::TDK_Success;
3173 // Strip off references on the argument types; they aren't needed for
3174 // the following checks.
3175 if (const ReferenceType *DeducedARef = DeducedA->getAs<ReferenceType>())
3176 DeducedA = DeducedARef->getPointeeType();
3177 if (const ReferenceType *ARef = A->getAs<ReferenceType>())
3178 A = ARef->getPointeeType();
3180 // C++ [temp.deduct.call]p4:
3181 // [...] However, there are three cases that allow a difference:
3182 // - If the original P is a reference type, the deduced A (i.e., the
3183 // type referred to by the reference) can be more cv-qualified than
3184 // the transformed A.
3185 if (const ReferenceType *OriginalParamRef
3186 = OriginalParamType->getAs<ReferenceType>()) {
3187 // We don't want to keep the reference around any more.
3188 OriginalParamType = OriginalParamRef->getPointeeType();
3190 // FIXME: Resolve core issue (no number yet): if the original P is a
3191 // reference type and the transformed A is function type "noexcept F",
3192 // the deduced A can be F.
3194 if (A->isFunctionType() && S.IsFunctionConversion(A, DeducedA, Tmp))
3195 return Sema::TDK_Success;
3197 Qualifiers AQuals = A.getQualifiers();
3198 Qualifiers DeducedAQuals = DeducedA.getQualifiers();
3200 // Under Objective-C++ ARC, the deduced type may have implicitly
3201 // been given strong or (when dealing with a const reference)
3202 // unsafe_unretained lifetime. If so, update the original
3203 // qualifiers to include this lifetime.
3204 if (S.getLangOpts().ObjCAutoRefCount &&
3205 ((DeducedAQuals.getObjCLifetime() == Qualifiers::OCL_Strong &&
3206 AQuals.getObjCLifetime() == Qualifiers::OCL_None) ||
3207 (DeducedAQuals.hasConst() &&
3208 DeducedAQuals.getObjCLifetime() == Qualifiers::OCL_ExplicitNone))) {
3209 AQuals.setObjCLifetime(DeducedAQuals.getObjCLifetime());
3212 if (AQuals == DeducedAQuals) {
3213 // Qualifiers match; there's nothing to do.
3214 } else if (!DeducedAQuals.compatiblyIncludes(AQuals)) {
3217 // Qualifiers are compatible, so have the argument type adopt the
3218 // deduced argument type's qualifiers as if we had performed the
3219 // qualification conversion.
3220 A = Context.getQualifiedType(A.getUnqualifiedType(), DeducedAQuals);
3224 // - The transformed A can be another pointer or pointer to member
3225 // type that can be converted to the deduced A via a function pointer
3226 // conversion and/or a qualification conversion.
3228 // Also allow conversions which merely strip __attribute__((noreturn)) from
3229 // function types (recursively).
3230 bool ObjCLifetimeConversion = false;
3232 if ((A->isAnyPointerType() || A->isMemberPointerType()) &&
3233 (S.IsQualificationConversion(A, DeducedA, false,
3234 ObjCLifetimeConversion) ||
3235 S.IsFunctionConversion(A, DeducedA, ResultTy)))
3236 return Sema::TDK_Success;
3238 // - If P is a class and P has the form simple-template-id, then the
3239 // transformed A can be a derived class of the deduced A. [...]
3240 // [...] Likewise, if P is a pointer to a class of the form
3241 // simple-template-id, the transformed A can be a pointer to a
3242 // derived class pointed to by the deduced A.
3243 if (const PointerType *OriginalParamPtr
3244 = OriginalParamType->getAs<PointerType>()) {
3245 if (const PointerType *DeducedAPtr = DeducedA->getAs<PointerType>()) {
3246 if (const PointerType *APtr = A->getAs<PointerType>()) {
3247 if (A->getPointeeType()->isRecordType()) {
3248 OriginalParamType = OriginalParamPtr->getPointeeType();
3249 DeducedA = DeducedAPtr->getPointeeType();
3250 A = APtr->getPointeeType();
3256 if (Context.hasSameUnqualifiedType(A, DeducedA))
3257 return Sema::TDK_Success;
3259 if (A->isRecordType() && isSimpleTemplateIdType(OriginalParamType) &&
3260 S.IsDerivedFrom(Info.getLocation(), A, DeducedA))
3261 return Sema::TDK_Success;
3266 /// Find the pack index for a particular parameter index in an instantiation of
3267 /// a function template with specific arguments.
3269 /// \return The pack index for whichever pack produced this parameter, or -1
3270 /// if this was not produced by a parameter. Intended to be used as the
3271 /// ArgumentPackSubstitutionIndex for further substitutions.
3272 // FIXME: We should track this in OriginalCallArgs so we don't need to
3273 // reconstruct it here.
3274 static unsigned getPackIndexForParam(Sema &S,
3275 FunctionTemplateDecl *FunctionTemplate,
3276 const MultiLevelTemplateArgumentList &Args,
3277 unsigned ParamIdx) {
3279 for (auto *PD : FunctionTemplate->getTemplatedDecl()->parameters()) {
3280 if (PD->isParameterPack()) {
3281 unsigned NumExpansions =
3282 S.getNumArgumentsInExpansion(PD->getType(), Args).getValueOr(1);
3283 if (Idx + NumExpansions > ParamIdx)
3284 return ParamIdx - Idx;
3285 Idx += NumExpansions;
3287 if (Idx == ParamIdx)
3288 return -1; // Not a pack expansion
3293 llvm_unreachable("parameter index would not be produced from template");
3296 /// Finish template argument deduction for a function template,
3297 /// checking the deduced template arguments for completeness and forming
3298 /// the function template specialization.
3300 /// \param OriginalCallArgs If non-NULL, the original call arguments against
3301 /// which the deduced argument types should be compared.
3302 Sema::TemplateDeductionResult Sema::FinishTemplateArgumentDeduction(
3303 FunctionTemplateDecl *FunctionTemplate,
3304 SmallVectorImpl<DeducedTemplateArgument> &Deduced,
3305 unsigned NumExplicitlySpecified, FunctionDecl *&Specialization,
3306 TemplateDeductionInfo &Info,
3307 SmallVectorImpl<OriginalCallArg> const *OriginalCallArgs,
3308 bool PartialOverloading, llvm::function_ref<bool()> CheckNonDependent) {
3309 // Unevaluated SFINAE context.
3310 EnterExpressionEvaluationContext Unevaluated(
3311 *this, Sema::ExpressionEvaluationContext::Unevaluated);
3312 SFINAETrap Trap(*this);
3314 // Enter a new template instantiation context while we instantiate the
3315 // actual function declaration.
3316 SmallVector<TemplateArgument, 4> DeducedArgs(Deduced.begin(), Deduced.end());
3317 InstantiatingTemplate Inst(
3318 *this, Info.getLocation(), FunctionTemplate, DeducedArgs,
3319 CodeSynthesisContext::DeducedTemplateArgumentSubstitution, Info);
3320 if (Inst.isInvalid())
3321 return TDK_InstantiationDepth;
3323 ContextRAII SavedContext(*this, FunctionTemplate->getTemplatedDecl());
3325 // C++ [temp.deduct.type]p2:
3326 // [...] or if any template argument remains neither deduced nor
3327 // explicitly specified, template argument deduction fails.
3328 SmallVector<TemplateArgument, 4> Builder;
3329 if (auto Result = ConvertDeducedTemplateArguments(
3330 *this, FunctionTemplate, /*IsDeduced*/true, Deduced, Info, Builder,
3331 CurrentInstantiationScope, NumExplicitlySpecified,
3332 PartialOverloading))
3335 // C++ [temp.deduct.call]p10: [DR1391]
3336 // If deduction succeeds for all parameters that contain
3337 // template-parameters that participate in template argument deduction,
3338 // and all template arguments are explicitly specified, deduced, or
3339 // obtained from default template arguments, remaining parameters are then
3340 // compared with the corresponding arguments. For each remaining parameter
3341 // P with a type that was non-dependent before substitution of any
3342 // explicitly-specified template arguments, if the corresponding argument
3343 // A cannot be implicitly converted to P, deduction fails.
3344 if (CheckNonDependent())
3345 return TDK_NonDependentConversionFailure;
3347 // Form the template argument list from the deduced template arguments.
3348 TemplateArgumentList *DeducedArgumentList
3349 = TemplateArgumentList::CreateCopy(Context, Builder);
3350 Info.reset(DeducedArgumentList);
3352 // Substitute the deduced template arguments into the function template
3353 // declaration to produce the function template specialization.
3354 DeclContext *Owner = FunctionTemplate->getDeclContext();
3355 if (FunctionTemplate->getFriendObjectKind())
3356 Owner = FunctionTemplate->getLexicalDeclContext();
3357 MultiLevelTemplateArgumentList SubstArgs(*DeducedArgumentList);
3358 Specialization = cast_or_null<FunctionDecl>(
3359 SubstDecl(FunctionTemplate->getTemplatedDecl(), Owner, SubstArgs));
3360 if (!Specialization || Specialization->isInvalidDecl())
3361 return TDK_SubstitutionFailure;
3363 assert(Specialization->getPrimaryTemplate()->getCanonicalDecl() ==
3364 FunctionTemplate->getCanonicalDecl());
3366 // If the template argument list is owned by the function template
3367 // specialization, release it.
3368 if (Specialization->getTemplateSpecializationArgs() == DeducedArgumentList &&
3369 !Trap.hasErrorOccurred())
3372 // There may have been an error that did not prevent us from constructing a
3373 // declaration. Mark the declaration invalid and return with a substitution
3375 if (Trap.hasErrorOccurred()) {
3376 Specialization->setInvalidDecl(true);
3377 return TDK_SubstitutionFailure;
3380 if (OriginalCallArgs) {
3381 // C++ [temp.deduct.call]p4:
3382 // In general, the deduction process attempts to find template argument
3383 // values that will make the deduced A identical to A (after the type A
3384 // is transformed as described above). [...]
3385 llvm::SmallDenseMap<std::pair<unsigned, QualType>, QualType> DeducedATypes;
3386 for (unsigned I = 0, N = OriginalCallArgs->size(); I != N; ++I) {
3387 OriginalCallArg OriginalArg = (*OriginalCallArgs)[I];
3389 auto ParamIdx = OriginalArg.ArgIdx;
3390 if (ParamIdx >= Specialization->getNumParams())
3391 // FIXME: This presumably means a pack ended up smaller than we
3392 // expected while deducing. Should this not result in deduction
3393 // failure? Can it even happen?
3397 if (!OriginalArg.DecomposedParam) {
3398 // P is one of the function parameters, just look up its substituted
3400 DeducedA = Specialization->getParamDecl(ParamIdx)->getType();
3402 // P is a decomposed element of a parameter corresponding to a
3403 // braced-init-list argument. Substitute back into P to find the
3405 QualType &CacheEntry =
3406 DeducedATypes[{ParamIdx, OriginalArg.OriginalParamType}];
3407 if (CacheEntry.isNull()) {
3408 ArgumentPackSubstitutionIndexRAII PackIndex(
3409 *this, getPackIndexForParam(*this, FunctionTemplate, SubstArgs,
3412 SubstType(OriginalArg.OriginalParamType, SubstArgs,
3413 Specialization->getTypeSpecStartLoc(),
3414 Specialization->getDeclName());
3416 DeducedA = CacheEntry;
3420 CheckOriginalCallArgDeduction(*this, Info, OriginalArg, DeducedA))
3425 // If we suppressed any diagnostics while performing template argument
3426 // deduction, and if we haven't already instantiated this declaration,
3427 // keep track of these diagnostics. They'll be emitted if this specialization
3428 // is actually used.
3429 if (Info.diag_begin() != Info.diag_end()) {
3430 SuppressedDiagnosticsMap::iterator
3431 Pos = SuppressedDiagnostics.find(Specialization->getCanonicalDecl());
3432 if (Pos == SuppressedDiagnostics.end())
3433 SuppressedDiagnostics[Specialization->getCanonicalDecl()]
3434 .append(Info.diag_begin(), Info.diag_end());
3440 /// Gets the type of a function for template-argument-deducton
3441 /// purposes when it's considered as part of an overload set.
3442 static QualType GetTypeOfFunction(Sema &S, const OverloadExpr::FindResult &R,
3444 // We may need to deduce the return type of the function now.
3445 if (S.getLangOpts().CPlusPlus14 && Fn->getReturnType()->isUndeducedType() &&
3446 S.DeduceReturnType(Fn, R.Expression->getExprLoc(), /*Diagnose*/ false))
3449 if (CXXMethodDecl *Method = dyn_cast<CXXMethodDecl>(Fn))
3450 if (Method->isInstance()) {
3451 // An instance method that's referenced in a form that doesn't
3452 // look like a member pointer is just invalid.
3453 if (!R.HasFormOfMemberPointer)
3456 return S.Context.getMemberPointerType(Fn->getType(),
3457 S.Context.getTypeDeclType(Method->getParent()).getTypePtr());
3460 if (!R.IsAddressOfOperand) return Fn->getType();
3461 return S.Context.getPointerType(Fn->getType());
3464 /// Apply the deduction rules for overload sets.
3466 /// \return the null type if this argument should be treated as an
3467 /// undeduced context
3469 ResolveOverloadForDeduction(Sema &S, TemplateParameterList *TemplateParams,
3470 Expr *Arg, QualType ParamType,
3471 bool ParamWasReference) {
3473 OverloadExpr::FindResult R = OverloadExpr::find(Arg);
3475 OverloadExpr *Ovl = R.Expression;
3477 // C++0x [temp.deduct.call]p4
3479 if (ParamWasReference)
3480 TDF |= TDF_ParamWithReferenceType;
3481 if (R.IsAddressOfOperand)
3482 TDF |= TDF_IgnoreQualifiers;
3484 // C++0x [temp.deduct.call]p6:
3485 // When P is a function type, pointer to function type, or pointer
3486 // to member function type:
3488 if (!ParamType->isFunctionType() &&
3489 !ParamType->isFunctionPointerType() &&
3490 !ParamType->isMemberFunctionPointerType()) {
3491 if (Ovl->hasExplicitTemplateArgs()) {
3492 // But we can still look for an explicit specialization.
3493 if (FunctionDecl *ExplicitSpec
3494 = S.ResolveSingleFunctionTemplateSpecialization(Ovl))
3495 return GetTypeOfFunction(S, R, ExplicitSpec);
3499 if (FunctionDecl *Viable =
3500 S.resolveAddressOfOnlyViableOverloadCandidate(Arg, DAP))
3501 return GetTypeOfFunction(S, R, Viable);
3506 // Gather the explicit template arguments, if any.
3507 TemplateArgumentListInfo ExplicitTemplateArgs;
3508 if (Ovl->hasExplicitTemplateArgs())
3509 Ovl->copyTemplateArgumentsInto(ExplicitTemplateArgs);
3511 for (UnresolvedSetIterator I = Ovl->decls_begin(),
3512 E = Ovl->decls_end(); I != E; ++I) {
3513 NamedDecl *D = (*I)->getUnderlyingDecl();
3515 if (FunctionTemplateDecl *FunTmpl = dyn_cast<FunctionTemplateDecl>(D)) {
3516 // - If the argument is an overload set containing one or more
3517 // function templates, the parameter is treated as a
3518 // non-deduced context.
3519 if (!Ovl->hasExplicitTemplateArgs())
3522 // Otherwise, see if we can resolve a function type
3523 FunctionDecl *Specialization = nullptr;
3524 TemplateDeductionInfo Info(Ovl->getNameLoc());
3525 if (S.DeduceTemplateArguments(FunTmpl, &ExplicitTemplateArgs,
3526 Specialization, Info))
3532 FunctionDecl *Fn = cast<FunctionDecl>(D);
3533 QualType ArgType = GetTypeOfFunction(S, R, Fn);
3534 if (ArgType.isNull()) continue;
3536 // Function-to-pointer conversion.
3537 if (!ParamWasReference && ParamType->isPointerType() &&
3538 ArgType->isFunctionType())
3539 ArgType = S.Context.getPointerType(ArgType);
3541 // - If the argument is an overload set (not containing function
3542 // templates), trial argument deduction is attempted using each
3543 // of the members of the set. If deduction succeeds for only one
3544 // of the overload set members, that member is used as the
3545 // argument value for the deduction. If deduction succeeds for
3546 // more than one member of the overload set the parameter is
3547 // treated as a non-deduced context.
3549 // We do all of this in a fresh context per C++0x [temp.deduct.type]p2:
3550 // Type deduction is done independently for each P/A pair, and
3551 // the deduced template argument values are then combined.
3552 // So we do not reject deductions which were made elsewhere.
3553 SmallVector<DeducedTemplateArgument, 8>
3554 Deduced(TemplateParams->size());
3555 TemplateDeductionInfo Info(Ovl->getNameLoc());
3556 Sema::TemplateDeductionResult Result
3557 = DeduceTemplateArgumentsByTypeMatch(S, TemplateParams, ParamType,
3558 ArgType, Info, Deduced, TDF);
3559 if (Result) continue;
3560 if (!Match.isNull())
3568 /// Perform the adjustments to the parameter and argument types
3569 /// described in C++ [temp.deduct.call].
3571 /// \returns true if the caller should not attempt to perform any template
3572 /// argument deduction based on this P/A pair because the argument is an
3573 /// overloaded function set that could not be resolved.
3574 static bool AdjustFunctionParmAndArgTypesForDeduction(
3575 Sema &S, TemplateParameterList *TemplateParams, unsigned FirstInnerIndex,
3576 QualType &ParamType, QualType &ArgType, Expr *Arg, unsigned &TDF) {
3577 // C++0x [temp.deduct.call]p3:
3578 // If P is a cv-qualified type, the top level cv-qualifiers of P's type
3579 // are ignored for type deduction.
3580 if (ParamType.hasQualifiers())
3581 ParamType = ParamType.getUnqualifiedType();
3583 // [...] If P is a reference type, the type referred to by P is
3584 // used for type deduction.
3585 const ReferenceType *ParamRefType = ParamType->getAs<ReferenceType>();
3587 ParamType = ParamRefType->getPointeeType();
3589 // Overload sets usually make this parameter an undeduced context,
3590 // but there are sometimes special circumstances. Typically
3591 // involving a template-id-expr.
3592 if (ArgType == S.Context.OverloadTy) {
3593 ArgType = ResolveOverloadForDeduction(S, TemplateParams,
3595 ParamRefType != nullptr);
3596 if (ArgType.isNull())
3601 // If the argument has incomplete array type, try to complete its type.
3602 if (ArgType->isIncompleteArrayType()) {
3603 S.completeExprArrayBound(Arg);
3604 ArgType = Arg->getType();
3607 // C++1z [temp.deduct.call]p3:
3608 // If P is a forwarding reference and the argument is an lvalue, the type
3609 // "lvalue reference to A" is used in place of A for type deduction.
3610 if (isForwardingReference(QualType(ParamRefType, 0), FirstInnerIndex) &&
3612 ArgType = S.Context.getLValueReferenceType(ArgType);
3614 // C++ [temp.deduct.call]p2:
3615 // If P is not a reference type:
3616 // - If A is an array type, the pointer type produced by the
3617 // array-to-pointer standard conversion (4.2) is used in place of
3618 // A for type deduction; otherwise,
3619 if (ArgType->isArrayType())
3620 ArgType = S.Context.getArrayDecayedType(ArgType);
3621 // - If A is a function type, the pointer type produced by the
3622 // function-to-pointer standard conversion (4.3) is used in place
3623 // of A for type deduction; otherwise,
3624 else if (ArgType->isFunctionType())
3625 ArgType = S.Context.getPointerType(ArgType);
3627 // - If A is a cv-qualified type, the top level cv-qualifiers of A's
3628 // type are ignored for type deduction.
3629 ArgType = ArgType.getUnqualifiedType();
3633 // C++0x [temp.deduct.call]p4:
3634 // In general, the deduction process attempts to find template argument
3635 // values that will make the deduced A identical to A (after the type A
3636 // is transformed as described above). [...]
3637 TDF = TDF_SkipNonDependent;
3639 // - If the original P is a reference type, the deduced A (i.e., the
3640 // type referred to by the reference) can be more cv-qualified than
3641 // the transformed A.
3643 TDF |= TDF_ParamWithReferenceType;
3644 // - The transformed A can be another pointer or pointer to member
3645 // type that can be converted to the deduced A via a qualification
3646 // conversion (4.4).
3647 if (ArgType->isPointerType() || ArgType->isMemberPointerType() ||
3648 ArgType->isObjCObjectPointerType())
3649 TDF |= TDF_IgnoreQualifiers;
3650 // - If P is a class and P has the form simple-template-id, then the
3651 // transformed A can be a derived class of the deduced A. Likewise,
3652 // if P is a pointer to a class of the form simple-template-id, the
3653 // transformed A can be a pointer to a derived class pointed to by
3655 if (isSimpleTemplateIdType(ParamType) ||
3656 (isa<PointerType>(ParamType) &&
3657 isSimpleTemplateIdType(
3658 ParamType->getAs<PointerType>()->getPointeeType())))
3659 TDF |= TDF_DerivedClass;
3665 hasDeducibleTemplateParameters(Sema &S, FunctionTemplateDecl *FunctionTemplate,
3668 static Sema::TemplateDeductionResult DeduceTemplateArgumentsFromCallArgument(
3669 Sema &S, TemplateParameterList *TemplateParams, unsigned FirstInnerIndex,
3670 QualType ParamType, Expr *Arg, TemplateDeductionInfo &Info,
3671 SmallVectorImpl<DeducedTemplateArgument> &Deduced,
3672 SmallVectorImpl<Sema::OriginalCallArg> &OriginalCallArgs,
3673 bool DecomposedParam, unsigned ArgIdx, unsigned TDF);
3675 /// Attempt template argument deduction from an initializer list
3676 /// deemed to be an argument in a function call.
3677 static Sema::TemplateDeductionResult DeduceFromInitializerList(
3678 Sema &S, TemplateParameterList *TemplateParams, QualType AdjustedParamType,
3679 InitListExpr *ILE, TemplateDeductionInfo &Info,
3680 SmallVectorImpl<DeducedTemplateArgument> &Deduced,
3681 SmallVectorImpl<Sema::OriginalCallArg> &OriginalCallArgs, unsigned ArgIdx,
3683 // C++ [temp.deduct.call]p1: (CWG 1591)
3684 // If removing references and cv-qualifiers from P gives
3685 // std::initializer_list<P0> or P0[N] for some P0 and N and the argument is
3686 // a non-empty initializer list, then deduction is performed instead for
3687 // each element of the initializer list, taking P0 as a function template
3688 // parameter type and the initializer element as its argument
3690 // We've already removed references and cv-qualifiers here.
3691 if (!ILE->getNumInits())
3692 return Sema::TDK_Success;
3695 auto *ArrTy = S.Context.getAsArrayType(AdjustedParamType);
3697 ElTy = ArrTy->getElementType();
3698 else if (!S.isStdInitializerList(AdjustedParamType, &ElTy)) {
3699 // Otherwise, an initializer list argument causes the parameter to be
3700 // considered a non-deduced context
3701 return Sema::TDK_Success;
3704 // Deduction only needs to be done for dependent types.
3705 if (ElTy->isDependentType()) {
3706 for (Expr *E : ILE->inits()) {
3707 if (auto Result = DeduceTemplateArgumentsFromCallArgument(
3708 S, TemplateParams, 0, ElTy, E, Info, Deduced, OriginalCallArgs, true,
3714 // in the P0[N] case, if N is a non-type template parameter, N is deduced
3715 // from the length of the initializer list.
3716 if (auto *DependentArrTy = dyn_cast_or_null<DependentSizedArrayType>(ArrTy)) {
3717 // Determine the array bound is something we can deduce.
3718 if (NonTypeTemplateParmDecl *NTTP =
3719 getDeducedParameterFromExpr(Info, DependentArrTy->getSizeExpr())) {
3720 // We can perform template argument deduction for the given non-type
3721 // template parameter.
3722 // C++ [temp.deduct.type]p13:
3723 // The type of N in the type T[N] is std::size_t.
3724 QualType T = S.Context.getSizeType();
3725 llvm::APInt Size(S.Context.getIntWidth(T), ILE->getNumInits());
3726 if (auto Result = DeduceNonTypeTemplateArgument(
3727 S, TemplateParams, NTTP, llvm::APSInt(Size), T,
3728 /*ArrayBound=*/true, Info, Deduced))
3733 return Sema::TDK_Success;
3736 /// Perform template argument deduction per [temp.deduct.call] for a
3737 /// single parameter / argument pair.
3738 static Sema::TemplateDeductionResult DeduceTemplateArgumentsFromCallArgument(
3739 Sema &S, TemplateParameterList *TemplateParams, unsigned FirstInnerIndex,
3740 QualType ParamType, Expr *Arg, TemplateDeductionInfo &Info,
3741 SmallVectorImpl<DeducedTemplateArgument> &Deduced,
3742 SmallVectorImpl<Sema::OriginalCallArg> &OriginalCallArgs,
3743 bool DecomposedParam, unsigned ArgIdx, unsigned TDF) {
3744 QualType ArgType = Arg->getType();
3745 QualType OrigParamType = ParamType;
3747 // If P is a reference type [...]
3748 // If P is a cv-qualified type [...]
3749 if (AdjustFunctionParmAndArgTypesForDeduction(
3750 S, TemplateParams, FirstInnerIndex, ParamType, ArgType, Arg, TDF))
3751 return Sema::TDK_Success;
3753 // If [...] the argument is a non-empty initializer list [...]
3754 if (InitListExpr *ILE = dyn_cast<InitListExpr>(Arg))
3755 return DeduceFromInitializerList(S, TemplateParams, ParamType, ILE, Info,
3756 Deduced, OriginalCallArgs, ArgIdx, TDF);
3758 // [...] the deduction process attempts to find template argument values
3759 // that will make the deduced A identical to A
3761 // Keep track of the argument type and corresponding parameter index,
3762 // so we can check for compatibility between the deduced A and A.
3763 OriginalCallArgs.push_back(
3764 Sema::OriginalCallArg(OrigParamType, DecomposedParam, ArgIdx, ArgType));
3765 return DeduceTemplateArgumentsByTypeMatch(S, TemplateParams, ParamType,
3766 ArgType, Info, Deduced, TDF);
3769 /// Perform template argument deduction from a function call
3770 /// (C++ [temp.deduct.call]).
3772 /// \param FunctionTemplate the function template for which we are performing
3773 /// template argument deduction.
3775 /// \param ExplicitTemplateArgs the explicit template arguments provided
3778 /// \param Args the function call arguments
3780 /// \param Specialization if template argument deduction was successful,
3781 /// this will be set to the function template specialization produced by
3782 /// template argument deduction.
3784 /// \param Info the argument will be updated to provide additional information
3785 /// about template argument deduction.
3787 /// \param CheckNonDependent A callback to invoke to check conversions for
3788 /// non-dependent parameters, between deduction and substitution, per DR1391.
3789 /// If this returns true, substitution will be skipped and we return
3790 /// TDK_NonDependentConversionFailure. The callback is passed the parameter
3791 /// types (after substituting explicit template arguments).
3793 /// \returns the result of template argument deduction.
3794 Sema::TemplateDeductionResult Sema::DeduceTemplateArguments(
3795 FunctionTemplateDecl *FunctionTemplate,
3796 TemplateArgumentListInfo *ExplicitTemplateArgs, ArrayRef<Expr *> Args,
3797 FunctionDecl *&Specialization, TemplateDeductionInfo &Info,
3798 bool PartialOverloading,
3799 llvm::function_ref<bool(ArrayRef<QualType>)> CheckNonDependent) {
3800 if (FunctionTemplate->isInvalidDecl())
3803 FunctionDecl *Function = FunctionTemplate->getTemplatedDecl();
3804 unsigned NumParams = Function->getNumParams();
3806 unsigned FirstInnerIndex = getFirstInnerIndex(FunctionTemplate);
3808 // C++ [temp.deduct.call]p1:
3809 // Template argument deduction is done by comparing each function template
3810 // parameter type (call it P) with the type of the corresponding argument
3811 // of the call (call it A) as described below.
3812 if (Args.size() < Function->getMinRequiredArguments() && !PartialOverloading)
3813 return TDK_TooFewArguments;
3814 else if (TooManyArguments(NumParams, Args.size(), PartialOverloading)) {
3815 const FunctionProtoType *Proto
3816 = Function->getType()->getAs<FunctionProtoType>();
3817 if (Proto->isTemplateVariadic())
3819 else if (!Proto->isVariadic())
3820 return TDK_TooManyArguments;
3823 // The types of the parameters from which we will perform template argument
3825 LocalInstantiationScope InstScope(*this);
3826 TemplateParameterList *TemplateParams
3827 = FunctionTemplate->getTemplateParameters();
3828 SmallVector<DeducedTemplateArgument, 4> Deduced;
3829 SmallVector<QualType, 8> ParamTypes;
3830 unsigned NumExplicitlySpecified = 0;
3831 if (ExplicitTemplateArgs) {
3832 TemplateDeductionResult Result =
3833 SubstituteExplicitTemplateArguments(FunctionTemplate,
3834 *ExplicitTemplateArgs,
3842 NumExplicitlySpecified = Deduced.size();
3844 // Just fill in the parameter types from the function declaration.
3845 for (unsigned I = 0; I != NumParams; ++I)
3846 ParamTypes.push_back(Function->getParamDecl(I)->getType());
3849 SmallVector<OriginalCallArg, 8> OriginalCallArgs;
3851 // Deduce an argument of type ParamType from an expression with index ArgIdx.
3852 auto DeduceCallArgument = [&](QualType ParamType, unsigned ArgIdx) {
3853 // C++ [demp.deduct.call]p1: (DR1391)
3854 // Template argument deduction is done by comparing each function template
3855 // parameter that contains template-parameters that participate in
3856 // template argument deduction ...
3857 if (!hasDeducibleTemplateParameters(*this, FunctionTemplate, ParamType))
3858 return Sema::TDK_Success;
3860 // ... with the type of the corresponding argument
3861 return DeduceTemplateArgumentsFromCallArgument(
3862 *this, TemplateParams, FirstInnerIndex, ParamType, Args[ArgIdx], Info, Deduced,
3863 OriginalCallArgs, /*Decomposed*/false, ArgIdx, /*TDF*/ 0);
3866 // Deduce template arguments from the function parameters.
3867 Deduced.resize(TemplateParams->size());
3868 SmallVector<QualType, 8> ParamTypesForArgChecking;
3869 for (unsigned ParamIdx = 0, NumParamTypes = ParamTypes.size(), ArgIdx = 0;
3870 ParamIdx != NumParamTypes; ++ParamIdx) {
3871 QualType ParamType = ParamTypes[ParamIdx];
3873 const PackExpansionType *ParamExpansion =
3874 dyn_cast<PackExpansionType>(ParamType);
3875 if (!ParamExpansion) {
3876 // Simple case: matching a function parameter to a function argument.
3877 if (ArgIdx >= Args.size())
3880 ParamTypesForArgChecking.push_back(ParamType);
3881 if (auto Result = DeduceCallArgument(ParamType, ArgIdx++))
3887 QualType ParamPattern = ParamExpansion->getPattern();
3888 PackDeductionScope PackScope(*this, TemplateParams, Deduced, Info,
3891 // C++0x [temp.deduct.call]p1:
3892 // For a function parameter pack that occurs at the end of the
3893 // parameter-declaration-list, the type A of each remaining argument of
3894 // the call is compared with the type P of the declarator-id of the
3895 // function parameter pack. Each comparison deduces template arguments
3896 // for subsequent positions in the template parameter packs expanded by
3897 // the function parameter pack. When a function parameter pack appears
3898 // in a non-deduced context [not at the end of the list], the type of
3899 // that parameter pack is never deduced.
3901 // FIXME: The above rule allows the size of the parameter pack to change
3902 // after we skip it (in the non-deduced case). That makes no sense, so
3903 // we instead notionally deduce the pack against N arguments, where N is
3904 // the length of the explicitly-specified pack if it's expanded by the
3905 // parameter pack and 0 otherwise, and we treat each deduction as a
3906 // non-deduced context.
3907 if (ParamIdx + 1 == NumParamTypes || PackScope.hasFixedArity()) {
3908 for (; ArgIdx < Args.size() && PackScope.hasNextElement();
3909 PackScope.nextPackElement(), ++ArgIdx) {
3910 ParamTypesForArgChecking.push_back(ParamPattern);
3911 if (auto Result = DeduceCallArgument(ParamPattern, ArgIdx))
3915 // If the parameter type contains an explicitly-specified pack that we
3916 // could not expand, skip the number of parameters notionally created
3917 // by the expansion.
3918 Optional<unsigned> NumExpansions = ParamExpansion->getNumExpansions();
3919 if (NumExpansions && !PackScope.isPartiallyExpanded()) {
3920 for (unsigned I = 0; I != *NumExpansions && ArgIdx < Args.size();
3922 ParamTypesForArgChecking.push_back(ParamPattern);
3923 // FIXME: Should we add OriginalCallArgs for these? What if the
3924 // corresponding argument is a list?
3925 PackScope.nextPackElement();
3930 // Build argument packs for each of the parameter packs expanded by this
3932 if (auto Result = PackScope.finish())
3936 // Capture the context in which the function call is made. This is the context
3937 // that is needed when the accessibility of template arguments is checked.
3938 DeclContext *CallingCtx = CurContext;
3940 return FinishTemplateArgumentDeduction(
3941 FunctionTemplate, Deduced, NumExplicitlySpecified, Specialization, Info,
3942 &OriginalCallArgs, PartialOverloading, [&, CallingCtx]() {
3943 ContextRAII SavedContext(*this, CallingCtx);
3944 return CheckNonDependent(ParamTypesForArgChecking);
3948 QualType Sema::adjustCCAndNoReturn(QualType ArgFunctionType,
3949 QualType FunctionType,
3950 bool AdjustExceptionSpec) {
3951 if (ArgFunctionType.isNull())
3952 return ArgFunctionType;
3954 const FunctionProtoType *FunctionTypeP =
3955 FunctionType->castAs<FunctionProtoType>();
3956 const FunctionProtoType *ArgFunctionTypeP =
3957 ArgFunctionType->getAs<FunctionProtoType>();
3959 FunctionProtoType::ExtProtoInfo EPI = ArgFunctionTypeP->getExtProtoInfo();
3960 bool Rebuild = false;
3962 CallingConv CC = FunctionTypeP->getCallConv();
3963 if (EPI.ExtInfo.getCC() != CC) {
3964 EPI.ExtInfo = EPI.ExtInfo.withCallingConv(CC);
3968 bool NoReturn = FunctionTypeP->getNoReturnAttr();
3969 if (EPI.ExtInfo.getNoReturn() != NoReturn) {
3970 EPI.ExtInfo = EPI.ExtInfo.withNoReturn(NoReturn);
3974 if (AdjustExceptionSpec && (FunctionTypeP->hasExceptionSpec() ||
3975 ArgFunctionTypeP->hasExceptionSpec())) {
3976 EPI.ExceptionSpec = FunctionTypeP->getExtProtoInfo().ExceptionSpec;
3981 return ArgFunctionType;
3983 return Context.getFunctionType(ArgFunctionTypeP->getReturnType(),
3984 ArgFunctionTypeP->getParamTypes(), EPI);
3987 /// Deduce template arguments when taking the address of a function
3988 /// template (C++ [temp.deduct.funcaddr]) or matching a specialization to
3991 /// \param FunctionTemplate the function template for which we are performing
3992 /// template argument deduction.
3994 /// \param ExplicitTemplateArgs the explicitly-specified template
3997 /// \param ArgFunctionType the function type that will be used as the
3998 /// "argument" type (A) when performing template argument deduction from the
3999 /// function template's function type. This type may be NULL, if there is no
4000 /// argument type to compare against, in C++0x [temp.arg.explicit]p3.
4002 /// \param Specialization if template argument deduction was successful,
4003 /// this will be set to the function template specialization produced by
4004 /// template argument deduction.
4006 /// \param Info the argument will be updated to provide additional information
4007 /// about template argument deduction.
4009 /// \param IsAddressOfFunction If \c true, we are deducing as part of taking
4010 /// the address of a function template per [temp.deduct.funcaddr] and
4011 /// [over.over]. If \c false, we are looking up a function template
4012 /// specialization based on its signature, per [temp.deduct.decl].
4014 /// \returns the result of template argument deduction.
4015 Sema::TemplateDeductionResult Sema::DeduceTemplateArguments(
4016 FunctionTemplateDecl *FunctionTemplate,
4017 TemplateArgumentListInfo *ExplicitTemplateArgs, QualType ArgFunctionType,
4018 FunctionDecl *&Specialization, TemplateDeductionInfo &Info,
4019 bool IsAddressOfFunction) {
4020 if (FunctionTemplate->isInvalidDecl())
4023 FunctionDecl *Function = FunctionTemplate->getTemplatedDecl();
4024 TemplateParameterList *TemplateParams
4025 = FunctionTemplate->getTemplateParameters();
4026 QualType FunctionType = Function->getType();
4028 // Substitute any explicit template arguments.
4029 LocalInstantiationScope InstScope(*this);
4030 SmallVector<DeducedTemplateArgument, 4> Deduced;
4031 unsigned NumExplicitlySpecified = 0;
4032 SmallVector<QualType, 4> ParamTypes;
4033 if (ExplicitTemplateArgs) {
4034 if (TemplateDeductionResult Result
4035 = SubstituteExplicitTemplateArguments(FunctionTemplate,
4036 *ExplicitTemplateArgs,
4037 Deduced, ParamTypes,
4038 &FunctionType, Info))
4041 NumExplicitlySpecified = Deduced.size();
4044 // When taking the address of a function, we require convertibility of
4045 // the resulting function type. Otherwise, we allow arbitrary mismatches
4046 // of calling convention and noreturn.
4047 if (!IsAddressOfFunction)
4048 ArgFunctionType = adjustCCAndNoReturn(ArgFunctionType, FunctionType,
4049 /*AdjustExceptionSpec*/false);
4051 // Unevaluated SFINAE context.
4052 EnterExpressionEvaluationContext Unevaluated(
4053 *this, Sema::ExpressionEvaluationContext::Unevaluated);
4054 SFINAETrap Trap(*this);
4056 Deduced.resize(TemplateParams->size());
4058 // If the function has a deduced return type, substitute it for a dependent
4059 // type so that we treat it as a non-deduced context in what follows. If we
4060 // are looking up by signature, the signature type should also have a deduced
4061 // return type, which we instead expect to exactly match.
4062 bool HasDeducedReturnType = false;
4063 if (getLangOpts().CPlusPlus14 && IsAddressOfFunction &&
4064 Function->getReturnType()->getContainedAutoType()) {
4065 FunctionType = SubstAutoType(FunctionType, Context.DependentTy);
4066 HasDeducedReturnType = true;
4069 if (!ArgFunctionType.isNull()) {
4071 TDF_TopLevelParameterTypeList | TDF_AllowCompatibleFunctionType;
4072 // Deduce template arguments from the function type.
4073 if (TemplateDeductionResult Result
4074 = DeduceTemplateArgumentsByTypeMatch(*this, TemplateParams,
4075 FunctionType, ArgFunctionType,
4076 Info, Deduced, TDF))
4080 if (TemplateDeductionResult Result
4081 = FinishTemplateArgumentDeduction(FunctionTemplate, Deduced,
4082 NumExplicitlySpecified,
4083 Specialization, Info))
4086 // If the function has a deduced return type, deduce it now, so we can check
4087 // that the deduced function type matches the requested type.
4088 if (HasDeducedReturnType &&
4089 Specialization->getReturnType()->isUndeducedType() &&
4090 DeduceReturnType(Specialization, Info.getLocation(), false))
4091 return TDK_MiscellaneousDeductionFailure;
4093 // If the function has a dependent exception specification, resolve it now,
4094 // so we can check that the exception specification matches.
4095 auto *SpecializationFPT =
4096 Specialization->getType()->castAs<FunctionProtoType>();
4097 if (getLangOpts().CPlusPlus17 &&
4098 isUnresolvedExceptionSpec(SpecializationFPT->getExceptionSpecType()) &&
4099 !ResolveExceptionSpec(Info.getLocation(), SpecializationFPT))
4100 return TDK_MiscellaneousDeductionFailure;
4102 // Adjust the exception specification of the argument to match the
4103 // substituted and resolved type we just formed. (Calling convention and
4104 // noreturn can't be dependent, so we don't actually need this for them
4106 QualType SpecializationType = Specialization->getType();
4107 if (!IsAddressOfFunction)
4108 ArgFunctionType = adjustCCAndNoReturn(ArgFunctionType, SpecializationType,
4109 /*AdjustExceptionSpec*/true);
4111 // If the requested function type does not match the actual type of the
4112 // specialization with respect to arguments of compatible pointer to function
4113 // types, template argument deduction fails.
4114 if (!ArgFunctionType.isNull()) {
4115 if (IsAddressOfFunction &&
4116 !isSameOrCompatibleFunctionType(
4117 Context.getCanonicalType(SpecializationType),
4118 Context.getCanonicalType(ArgFunctionType)))
4119 return TDK_MiscellaneousDeductionFailure;
4121 if (!IsAddressOfFunction &&
4122 !Context.hasSameType(SpecializationType, ArgFunctionType))
4123 return TDK_MiscellaneousDeductionFailure;
4129 /// Deduce template arguments for a templated conversion
4130 /// function (C++ [temp.deduct.conv]) and, if successful, produce a
4131 /// conversion function template specialization.
4132 Sema::TemplateDeductionResult
4133 Sema::DeduceTemplateArguments(FunctionTemplateDecl *ConversionTemplate,
4135 CXXConversionDecl *&Specialization,
4136 TemplateDeductionInfo &Info) {
4137 if (ConversionTemplate->isInvalidDecl())
4140 CXXConversionDecl *ConversionGeneric
4141 = cast<CXXConversionDecl>(ConversionTemplate->getTemplatedDecl());
4143 QualType FromType = ConversionGeneric->getConversionType();
4145 // Canonicalize the types for deduction.
4146 QualType P = Context.getCanonicalType(FromType);
4147 QualType A = Context.getCanonicalType(ToType);
4149 // C++0x [temp.deduct.conv]p2:
4150 // If P is a reference type, the type referred to by P is used for
4152 if (const ReferenceType *PRef = P->getAs<ReferenceType>())
4153 P = PRef->getPointeeType();
4155 // C++0x [temp.deduct.conv]p4:
4156 // [...] If A is a reference type, the type referred to by A is used
4157 // for type deduction.
4158 if (const ReferenceType *ARef = A->getAs<ReferenceType>()) {
4159 A = ARef->getPointeeType();
4160 // We work around a defect in the standard here: cv-qualifiers are also
4161 // removed from P and A in this case, unless P was a reference type. This
4162 // seems to mostly match what other compilers are doing.
4163 if (!FromType->getAs<ReferenceType>()) {
4164 A = A.getUnqualifiedType();
4165 P = P.getUnqualifiedType();
4168 // C++ [temp.deduct.conv]p3:
4170 // If A is not a reference type:
4172 assert(!A->isReferenceType() && "Reference types were handled above");
4174 // - If P is an array type, the pointer type produced by the
4175 // array-to-pointer standard conversion (4.2) is used in place
4176 // of P for type deduction; otherwise,
4177 if (P->isArrayType())
4178 P = Context.getArrayDecayedType(P);
4179 // - If P is a function type, the pointer type produced by the
4180 // function-to-pointer standard conversion (4.3) is used in
4181 // place of P for type deduction; otherwise,
4182 else if (P->isFunctionType())
4183 P = Context.getPointerType(P);
4184 // - If P is a cv-qualified type, the top level cv-qualifiers of
4185 // P's type are ignored for type deduction.
4187 P = P.getUnqualifiedType();
4189 // C++0x [temp.deduct.conv]p4:
4190 // If A is a cv-qualified type, the top level cv-qualifiers of A's
4191 // type are ignored for type deduction. If A is a reference type, the type
4192 // referred to by A is used for type deduction.
4193 A = A.getUnqualifiedType();
4196 // Unevaluated SFINAE context.
4197 EnterExpressionEvaluationContext Unevaluated(
4198 *this, Sema::ExpressionEvaluationContext::Unevaluated);
4199 SFINAETrap Trap(*this);
4201 // C++ [temp.deduct.conv]p1:
4202 // Template argument deduction is done by comparing the return
4203 // type of the template conversion function (call it P) with the
4204 // type that is required as the result of the conversion (call it
4205 // A) as described in 14.8.2.4.
4206 TemplateParameterList *TemplateParams
4207 = ConversionTemplate->getTemplateParameters();
4208 SmallVector<DeducedTemplateArgument, 4> Deduced;
4209 Deduced.resize(TemplateParams->size());
4211 // C++0x [temp.deduct.conv]p4:
4212 // In general, the deduction process attempts to find template
4213 // argument values that will make the deduced A identical to
4214 // A. However, there are two cases that allow a difference:
4216 // - If the original A is a reference type, A can be more
4217 // cv-qualified than the deduced A (i.e., the type referred to
4218 // by the reference)
4219 if (ToType->isReferenceType())
4220 TDF |= TDF_ArgWithReferenceType;
4221 // - The deduced A can be another pointer or pointer to member
4222 // type that can be converted to A via a qualification
4225 // (C++0x [temp.deduct.conv]p6 clarifies that this only happens when
4226 // both P and A are pointers or member pointers. In this case, we
4227 // just ignore cv-qualifiers completely).
4228 if ((P->isPointerType() && A->isPointerType()) ||
4229 (P->isMemberPointerType() && A->isMemberPointerType()))
4230 TDF |= TDF_IgnoreQualifiers;
4231 if (TemplateDeductionResult Result
4232 = DeduceTemplateArgumentsByTypeMatch(*this, TemplateParams,
4233 P, A, Info, Deduced, TDF))
4236 // Create an Instantiation Scope for finalizing the operator.
4237 LocalInstantiationScope InstScope(*this);
4238 // Finish template argument deduction.
4239 FunctionDecl *ConversionSpecialized = nullptr;
4240 TemplateDeductionResult Result
4241 = FinishTemplateArgumentDeduction(ConversionTemplate, Deduced, 0,
4242 ConversionSpecialized, Info);
4243 Specialization = cast_or_null<CXXConversionDecl>(ConversionSpecialized);
4247 /// Deduce template arguments for a function template when there is
4248 /// nothing to deduce against (C++0x [temp.arg.explicit]p3).
4250 /// \param FunctionTemplate the function template for which we are performing
4251 /// template argument deduction.
4253 /// \param ExplicitTemplateArgs the explicitly-specified template
4256 /// \param Specialization if template argument deduction was successful,
4257 /// this will be set to the function template specialization produced by
4258 /// template argument deduction.
4260 /// \param Info the argument will be updated to provide additional information
4261 /// about template argument deduction.
4263 /// \param IsAddressOfFunction If \c true, we are deducing as part of taking
4264 /// the address of a function template in a context where we do not have a
4265 /// target type, per [over.over]. If \c false, we are looking up a function
4266 /// template specialization based on its signature, which only happens when
4267 /// deducing a function parameter type from an argument that is a template-id
4268 /// naming a function template specialization.
4270 /// \returns the result of template argument deduction.
4271 Sema::TemplateDeductionResult Sema::DeduceTemplateArguments(
4272 FunctionTemplateDecl *FunctionTemplate,
4273 TemplateArgumentListInfo *ExplicitTemplateArgs,
4274 FunctionDecl *&Specialization, TemplateDeductionInfo &Info,
4275 bool IsAddressOfFunction) {
4276 return DeduceTemplateArguments(FunctionTemplate, ExplicitTemplateArgs,
4277 QualType(), Specialization, Info,
4278 IsAddressOfFunction);
4283 /// Substitute the 'auto' specifier or deduced template specialization type
4284 /// specifier within a type for a given replacement type.
4285 class SubstituteDeducedTypeTransform :
4286 public TreeTransform<SubstituteDeducedTypeTransform> {
4287 QualType Replacement;
4291 SubstituteDeducedTypeTransform(Sema &SemaRef, QualType Replacement,
4292 bool UseTypeSugar = true)
4293 : TreeTransform<SubstituteDeducedTypeTransform>(SemaRef),
4294 Replacement(Replacement), UseTypeSugar(UseTypeSugar) {}
4296 QualType TransformDesugared(TypeLocBuilder &TLB, DeducedTypeLoc TL) {
4297 assert(isa<TemplateTypeParmType>(Replacement) &&
4298 "unexpected unsugared replacement kind");
4299 QualType Result = Replacement;
4300 TemplateTypeParmTypeLoc NewTL = TLB.push<TemplateTypeParmTypeLoc>(Result);
4301 NewTL.setNameLoc(TL.getNameLoc());
4305 QualType TransformAutoType(TypeLocBuilder &TLB, AutoTypeLoc TL) {
4306 // If we're building the type pattern to deduce against, don't wrap the
4307 // substituted type in an AutoType. Certain template deduction rules
4308 // apply only when a template type parameter appears directly (and not if
4309 // the parameter is found through desugaring). For instance:
4310 // auto &&lref = lvalue;
4311 // must transform into "rvalue reference to T" not "rvalue reference to
4312 // auto type deduced as T" in order for [temp.deduct.call]p3 to apply.
4314 // FIXME: Is this still necessary?
4316 return TransformDesugared(TLB, TL);
4318 QualType Result = SemaRef.Context.getAutoType(
4319 Replacement, TL.getTypePtr()->getKeyword(), Replacement.isNull());
4320 auto NewTL = TLB.push<AutoTypeLoc>(Result);
4321 NewTL.setNameLoc(TL.getNameLoc());
4325 QualType TransformDeducedTemplateSpecializationType(
4326 TypeLocBuilder &TLB, DeducedTemplateSpecializationTypeLoc TL) {
4328 return TransformDesugared(TLB, TL);
4330 QualType Result = SemaRef.Context.getDeducedTemplateSpecializationType(
4331 TL.getTypePtr()->getTemplateName(),
4332 Replacement, Replacement.isNull());
4333 auto NewTL = TLB.push<DeducedTemplateSpecializationTypeLoc>(Result);
4334 NewTL.setNameLoc(TL.getNameLoc());
4338 ExprResult TransformLambdaExpr(LambdaExpr *E) {
4339 // Lambdas never need to be transformed.
4343 QualType Apply(TypeLoc TL) {
4344 // Create some scratch storage for the transformed type locations.
4345 // FIXME: We're just going to throw this information away. Don't build it.
4347 TLB.reserve(TL.getFullDataSize());
4348 return TransformType(TLB, TL);
4354 Sema::DeduceAutoResult
4355 Sema::DeduceAutoType(TypeSourceInfo *Type, Expr *&Init, QualType &Result,
4356 Optional<unsigned> DependentDeductionDepth) {
4357 return DeduceAutoType(Type->getTypeLoc(), Init, Result,
4358 DependentDeductionDepth);
4361 /// Attempt to produce an informative diagostic explaining why auto deduction
4363 /// \return \c true if diagnosed, \c false if not.
4364 static bool diagnoseAutoDeductionFailure(Sema &S,
4365 Sema::TemplateDeductionResult TDK,
4366 TemplateDeductionInfo &Info,
4367 ArrayRef<SourceRange> Ranges) {
4369 case Sema::TDK_Inconsistent: {
4370 // Inconsistent deduction means we were deducing from an initializer list.
4371 auto D = S.Diag(Info.getLocation(), diag::err_auto_inconsistent_deduction);
4372 D << Info.FirstArg << Info.SecondArg;
4373 for (auto R : Ranges)
4378 // FIXME: Are there other cases for which a custom diagnostic is more useful
4379 // than the basic "types don't match" diagnostic?
4386 /// Deduce the type for an auto type-specifier (C++11 [dcl.spec.auto]p6)
4388 /// Note that this is done even if the initializer is dependent. (This is
4389 /// necessary to support partial ordering of templates using 'auto'.)
4390 /// A dependent type will be produced when deducing from a dependent type.
4392 /// \param Type the type pattern using the auto type-specifier.
4393 /// \param Init the initializer for the variable whose type is to be deduced.
4394 /// \param Result if type deduction was successful, this will be set to the
4396 /// \param DependentDeductionDepth Set if we should permit deduction in
4397 /// dependent cases. This is necessary for template partial ordering with
4398 /// 'auto' template parameters. The value specified is the template
4399 /// parameter depth at which we should perform 'auto' deduction.
4400 Sema::DeduceAutoResult
4401 Sema::DeduceAutoType(TypeLoc Type, Expr *&Init, QualType &Result,
4402 Optional<unsigned> DependentDeductionDepth) {
4403 if (Init->getType()->isNonOverloadPlaceholderType()) {
4404 ExprResult NonPlaceholder = CheckPlaceholderExpr(Init);
4405 if (NonPlaceholder.isInvalid())
4406 return DAR_FailedAlreadyDiagnosed;
4407 Init = NonPlaceholder.get();
4410 if (!DependentDeductionDepth &&
4411 (Type.getType()->isDependentType() || Init->isTypeDependent())) {
4412 Result = SubstituteDeducedTypeTransform(*this, QualType()).Apply(Type);
4413 assert(!Result.isNull() && "substituting DependentTy can't fail");
4414 return DAR_Succeeded;
4417 // Find the depth of template parameter to synthesize.
4418 unsigned Depth = DependentDeductionDepth.getValueOr(0);
4420 // If this is a 'decltype(auto)' specifier, do the decltype dance.
4421 // Since 'decltype(auto)' can only occur at the top of the type, we
4422 // don't need to go digging for it.
4423 if (const AutoType *AT = Type.getType()->getAs<AutoType>()) {
4424 if (AT->isDecltypeAuto()) {
4425 if (isa<InitListExpr>(Init)) {
4426 Diag(Init->getLocStart(), diag::err_decltype_auto_initializer_list);
4427 return DAR_FailedAlreadyDiagnosed;
4430 QualType Deduced = BuildDecltypeType(Init, Init->getLocStart(), false);
4431 if (Deduced.isNull())
4432 return DAR_FailedAlreadyDiagnosed;
4433 // FIXME: Support a non-canonical deduced type for 'auto'.
4434 Deduced = Context.getCanonicalType(Deduced);
4435 Result = SubstituteDeducedTypeTransform(*this, Deduced).Apply(Type);
4436 if (Result.isNull())
4437 return DAR_FailedAlreadyDiagnosed;
4438 return DAR_Succeeded;
4439 } else if (!getLangOpts().CPlusPlus) {
4440 if (isa<InitListExpr>(Init)) {
4441 Diag(Init->getLocStart(), diag::err_auto_init_list_from_c);
4442 return DAR_FailedAlreadyDiagnosed;
4447 SourceLocation Loc = Init->getExprLoc();
4449 LocalInstantiationScope InstScope(*this);
4451 // Build template<class TemplParam> void Func(FuncParam);
4452 TemplateTypeParmDecl *TemplParam = TemplateTypeParmDecl::Create(
4453 Context, nullptr, SourceLocation(), Loc, Depth, 0, nullptr, false, false);
4454 QualType TemplArg = QualType(TemplParam->getTypeForDecl(), 0);
4455 NamedDecl *TemplParamPtr = TemplParam;
4456 FixedSizeTemplateParameterListStorage<1, false> TemplateParamsSt(
4457 Loc, Loc, TemplParamPtr, Loc, nullptr);
4459 QualType FuncParam =
4460 SubstituteDeducedTypeTransform(*this, TemplArg, /*UseTypeSugar*/false)
4462 assert(!FuncParam.isNull() &&
4463 "substituting template parameter for 'auto' failed");
4465 // Deduce type of TemplParam in Func(Init)
4466 SmallVector<DeducedTemplateArgument, 1> Deduced;
4469 TemplateDeductionInfo Info(Loc, Depth);
4471 // If deduction failed, don't diagnose if the initializer is dependent; it
4472 // might acquire a matching type in the instantiation.
4473 auto DeductionFailed = [&](TemplateDeductionResult TDK,
4474 ArrayRef<SourceRange> Ranges) -> DeduceAutoResult {
4475 if (Init->isTypeDependent()) {
4476 Result = SubstituteDeducedTypeTransform(*this, QualType()).Apply(Type);
4477 assert(!Result.isNull() && "substituting DependentTy can't fail");
4478 return DAR_Succeeded;
4480 if (diagnoseAutoDeductionFailure(*this, TDK, Info, Ranges))
4481 return DAR_FailedAlreadyDiagnosed;
4485 SmallVector<OriginalCallArg, 4> OriginalCallArgs;
4487 InitListExpr *InitList = dyn_cast<InitListExpr>(Init);
4489 // Notionally, we substitute std::initializer_list<T> for 'auto' and deduce
4490 // against that. Such deduction only succeeds if removing cv-qualifiers and
4491 // references results in std::initializer_list<T>.
4492 if (!Type.getType().getNonReferenceType()->getAs<AutoType>())
4495 SourceRange DeducedFromInitRange;
4496 for (unsigned i = 0, e = InitList->getNumInits(); i < e; ++i) {
4497 Expr *Init = InitList->getInit(i);
4499 if (auto TDK = DeduceTemplateArgumentsFromCallArgument(
4500 *this, TemplateParamsSt.get(), 0, TemplArg, Init,
4501 Info, Deduced, OriginalCallArgs, /*Decomposed*/ true,
4502 /*ArgIdx*/ 0, /*TDF*/ 0))
4503 return DeductionFailed(TDK, {DeducedFromInitRange,
4504 Init->getSourceRange()});
4506 if (DeducedFromInitRange.isInvalid() &&
4507 Deduced[0].getKind() != TemplateArgument::Null)
4508 DeducedFromInitRange = Init->getSourceRange();
4511 if (!getLangOpts().CPlusPlus && Init->refersToBitField()) {
4512 Diag(Loc, diag::err_auto_bitfield);
4513 return DAR_FailedAlreadyDiagnosed;
4516 if (auto TDK = DeduceTemplateArgumentsFromCallArgument(
4517 *this, TemplateParamsSt.get(), 0, FuncParam, Init, Info, Deduced,
4518 OriginalCallArgs, /*Decomposed*/ false, /*ArgIdx*/ 0, /*TDF*/ 0))
4519 return DeductionFailed(TDK, {});
4522 // Could be null if somehow 'auto' appears in a non-deduced context.
4523 if (Deduced[0].getKind() != TemplateArgument::Type)
4524 return DeductionFailed(TDK_Incomplete, {});
4526 QualType DeducedType = Deduced[0].getAsType();
4529 DeducedType = BuildStdInitializerList(DeducedType, Loc);
4530 if (DeducedType.isNull())
4531 return DAR_FailedAlreadyDiagnosed;
4534 Result = SubstituteDeducedTypeTransform(*this, DeducedType).Apply(Type);
4535 if (Result.isNull())
4536 return DAR_FailedAlreadyDiagnosed;
4538 // Check that the deduced argument type is compatible with the original
4539 // argument type per C++ [temp.deduct.call]p4.
4540 QualType DeducedA = InitList ? Deduced[0].getAsType() : Result;
4541 for (const OriginalCallArg &OriginalArg : OriginalCallArgs) {
4542 assert((bool)InitList == OriginalArg.DecomposedParam &&
4543 "decomposed non-init-list in auto deduction?");
4545 CheckOriginalCallArgDeduction(*this, Info, OriginalArg, DeducedA)) {
4546 Result = QualType();
4547 return DeductionFailed(TDK, {});
4551 return DAR_Succeeded;
4554 QualType Sema::SubstAutoType(QualType TypeWithAuto,
4555 QualType TypeToReplaceAuto) {
4556 if (TypeToReplaceAuto->isDependentType())
4557 TypeToReplaceAuto = QualType();
4558 return SubstituteDeducedTypeTransform(*this, TypeToReplaceAuto)
4559 .TransformType(TypeWithAuto);
4562 TypeSourceInfo *Sema::SubstAutoTypeSourceInfo(TypeSourceInfo *TypeWithAuto,
4563 QualType TypeToReplaceAuto) {
4564 if (TypeToReplaceAuto->isDependentType())
4565 TypeToReplaceAuto = QualType();
4566 return SubstituteDeducedTypeTransform(*this, TypeToReplaceAuto)
4567 .TransformType(TypeWithAuto);
4570 QualType Sema::ReplaceAutoType(QualType TypeWithAuto,
4571 QualType TypeToReplaceAuto) {
4572 return SubstituteDeducedTypeTransform(*this, TypeToReplaceAuto,
4573 /*UseTypeSugar*/ false)
4574 .TransformType(TypeWithAuto);
4577 void Sema::DiagnoseAutoDeductionFailure(VarDecl *VDecl, Expr *Init) {
4578 if (isa<InitListExpr>(Init))
4579 Diag(VDecl->getLocation(),
4580 VDecl->isInitCapture()
4581 ? diag::err_init_capture_deduction_failure_from_init_list
4582 : diag::err_auto_var_deduction_failure_from_init_list)
4583 << VDecl->getDeclName() << VDecl->getType() << Init->getSourceRange();
4585 Diag(VDecl->getLocation(),
4586 VDecl->isInitCapture() ? diag::err_init_capture_deduction_failure
4587 : diag::err_auto_var_deduction_failure)
4588 << VDecl->getDeclName() << VDecl->getType() << Init->getType()
4589 << Init->getSourceRange();
4592 bool Sema::DeduceReturnType(FunctionDecl *FD, SourceLocation Loc,
4594 assert(FD->getReturnType()->isUndeducedType());
4596 // For a lambda's conversion operator, deduce any 'auto' or 'decltype(auto)'
4597 // within the return type from the call operator's type.
4598 if (isLambdaConversionOperator(FD)) {
4599 CXXRecordDecl *Lambda = cast<CXXMethodDecl>(FD)->getParent();
4600 FunctionDecl *CallOp = Lambda->getLambdaCallOperator();
4602 // For a generic lambda, instantiate the call operator if needed.
4603 if (auto *Args = FD->getTemplateSpecializationArgs()) {
4604 CallOp = InstantiateFunctionDeclaration(
4605 CallOp->getDescribedFunctionTemplate(), Args, Loc);
4606 if (!CallOp || CallOp->isInvalidDecl())
4609 // We might need to deduce the return type by instantiating the definition
4610 // of the operator() function.
4611 if (CallOp->getReturnType()->isUndeducedType())
4612 InstantiateFunctionDefinition(Loc, CallOp);
4615 if (CallOp->isInvalidDecl())
4617 assert(!CallOp->getReturnType()->isUndeducedType() &&
4618 "failed to deduce lambda return type");
4620 // Build the new return type from scratch.
4621 QualType RetType = getLambdaConversionFunctionResultType(
4622 CallOp->getType()->castAs<FunctionProtoType>());
4623 if (FD->getReturnType()->getAs<PointerType>())
4624 RetType = Context.getPointerType(RetType);
4626 assert(FD->getReturnType()->getAs<BlockPointerType>());
4627 RetType = Context.getBlockPointerType(RetType);
4629 Context.adjustDeducedFunctionResultType(FD, RetType);
4633 if (FD->getTemplateInstantiationPattern())
4634 InstantiateFunctionDefinition(Loc, FD);
4636 bool StillUndeduced = FD->getReturnType()->isUndeducedType();
4637 if (StillUndeduced && Diagnose && !FD->isInvalidDecl()) {
4638 Diag(Loc, diag::err_auto_fn_used_before_defined) << FD;
4639 Diag(FD->getLocation(), diag::note_callee_decl) << FD;
4642 return StillUndeduced;
4645 /// If this is a non-static member function,
4647 AddImplicitObjectParameterType(ASTContext &Context,
4648 CXXMethodDecl *Method,
4649 SmallVectorImpl<QualType> &ArgTypes) {
4650 // C++11 [temp.func.order]p3:
4651 // [...] The new parameter is of type "reference to cv A," where cv are
4652 // the cv-qualifiers of the function template (if any) and A is
4653 // the class of which the function template is a member.
4655 // The standard doesn't say explicitly, but we pick the appropriate kind of
4656 // reference type based on [over.match.funcs]p4.
4657 QualType ArgTy = Context.getTypeDeclType(Method->getParent());
4658 ArgTy = Context.getQualifiedType(ArgTy,
4659 Qualifiers::fromCVRMask(Method->getTypeQualifiers()));
4660 if (Method->getRefQualifier() == RQ_RValue)
4661 ArgTy = Context.getRValueReferenceType(ArgTy);
4663 ArgTy = Context.getLValueReferenceType(ArgTy);
4664 ArgTypes.push_back(ArgTy);
4667 /// Determine whether the function template \p FT1 is at least as
4668 /// specialized as \p FT2.
4669 static bool isAtLeastAsSpecializedAs(Sema &S,
4671 FunctionTemplateDecl *FT1,
4672 FunctionTemplateDecl *FT2,
4673 TemplatePartialOrderingContext TPOC,
4674 unsigned NumCallArguments1) {
4675 FunctionDecl *FD1 = FT1->getTemplatedDecl();
4676 FunctionDecl *FD2 = FT2->getTemplatedDecl();
4677 const FunctionProtoType *Proto1 = FD1->getType()->getAs<FunctionProtoType>();
4678 const FunctionProtoType *Proto2 = FD2->getType()->getAs<FunctionProtoType>();
4680 assert(Proto1 && Proto2 && "Function templates must have prototypes");
4681 TemplateParameterList *TemplateParams = FT2->getTemplateParameters();
4682 SmallVector<DeducedTemplateArgument, 4> Deduced;
4683 Deduced.resize(TemplateParams->size());
4685 // C++0x [temp.deduct.partial]p3:
4686 // The types used to determine the ordering depend on the context in which
4687 // the partial ordering is done:
4688 TemplateDeductionInfo Info(Loc);
4689 SmallVector<QualType, 4> Args2;
4692 // - In the context of a function call, the function parameter types are
4694 CXXMethodDecl *Method1 = dyn_cast<CXXMethodDecl>(FD1);
4695 CXXMethodDecl *Method2 = dyn_cast<CXXMethodDecl>(FD2);
4697 // C++11 [temp.func.order]p3:
4698 // [...] If only one of the function templates is a non-static
4699 // member, that function template is considered to have a new
4700 // first parameter inserted in its function parameter list. The
4701 // new parameter is of type "reference to cv A," where cv are
4702 // the cv-qualifiers of the function template (if any) and A is
4703 // the class of which the function template is a member.
4705 // Note that we interpret this to mean "if one of the function
4706 // templates is a non-static member and the other is a non-member";
4707 // otherwise, the ordering rules for static functions against non-static
4708 // functions don't make any sense.
4710 // C++98/03 doesn't have this provision but we've extended DR532 to cover
4711 // it as wording was broken prior to it.
4712 SmallVector<QualType, 4> Args1;
4714 unsigned NumComparedArguments = NumCallArguments1;
4716 if (!Method2 && Method1 && !Method1->isStatic()) {
4717 // Compare 'this' from Method1 against first parameter from Method2.
4718 AddImplicitObjectParameterType(S.Context, Method1, Args1);
4719 ++NumComparedArguments;
4720 } else if (!Method1 && Method2 && !Method2->isStatic()) {
4721 // Compare 'this' from Method2 against first parameter from Method1.
4722 AddImplicitObjectParameterType(S.Context, Method2, Args2);
4725 Args1.insert(Args1.end(), Proto1->param_type_begin(),
4726 Proto1->param_type_end());
4727 Args2.insert(Args2.end(), Proto2->param_type_begin(),
4728 Proto2->param_type_end());
4730 // C++ [temp.func.order]p5:
4731 // The presence of unused ellipsis and default arguments has no effect on
4732 // the partial ordering of function templates.
4733 if (Args1.size() > NumComparedArguments)
4734 Args1.resize(NumComparedArguments);
4735 if (Args2.size() > NumComparedArguments)
4736 Args2.resize(NumComparedArguments);
4737 if (DeduceTemplateArguments(S, TemplateParams, Args2.data(), Args2.size(),
4738 Args1.data(), Args1.size(), Info, Deduced,
4739 TDF_None, /*PartialOrdering=*/true))
4745 case TPOC_Conversion:
4746 // - In the context of a call to a conversion operator, the return types
4747 // of the conversion function templates are used.
4748 if (DeduceTemplateArgumentsByTypeMatch(
4749 S, TemplateParams, Proto2->getReturnType(), Proto1->getReturnType(),
4750 Info, Deduced, TDF_None,
4751 /*PartialOrdering=*/true))
4756 // - In other contexts (14.6.6.2) the function template's function type
4758 if (DeduceTemplateArgumentsByTypeMatch(S, TemplateParams,
4759 FD2->getType(), FD1->getType(),
4760 Info, Deduced, TDF_None,
4761 /*PartialOrdering=*/true))
4766 // C++0x [temp.deduct.partial]p11:
4767 // In most cases, all template parameters must have values in order for
4768 // deduction to succeed, but for partial ordering purposes a template
4769 // parameter may remain without a value provided it is not used in the
4770 // types being used for partial ordering. [ Note: a template parameter used
4771 // in a non-deduced context is considered used. -end note]
4772 unsigned ArgIdx = 0, NumArgs = Deduced.size();
4773 for (; ArgIdx != NumArgs; ++ArgIdx)
4774 if (Deduced[ArgIdx].isNull())
4777 // FIXME: We fail to implement [temp.deduct.type]p1 along this path. We need
4778 // to substitute the deduced arguments back into the template and check that
4779 // we get the right type.
4781 if (ArgIdx == NumArgs) {
4782 // All template arguments were deduced. FT1 is at least as specialized
4787 // Figure out which template parameters were used.
4788 llvm::SmallBitVector UsedParameters(TemplateParams->size());
4791 for (unsigned I = 0, N = Args2.size(); I != N; ++I)
4792 ::MarkUsedTemplateParameters(S.Context, Args2[I], false,
4793 TemplateParams->getDepth(),
4797 case TPOC_Conversion:
4798 ::MarkUsedTemplateParameters(S.Context, Proto2->getReturnType(), false,
4799 TemplateParams->getDepth(), UsedParameters);
4803 ::MarkUsedTemplateParameters(S.Context, FD2->getType(), false,
4804 TemplateParams->getDepth(),
4809 for (; ArgIdx != NumArgs; ++ArgIdx)
4810 // If this argument had no value deduced but was used in one of the types
4811 // used for partial ordering, then deduction fails.
4812 if (Deduced[ArgIdx].isNull() && UsedParameters[ArgIdx])
4818 /// Determine whether this a function template whose parameter-type-list
4819 /// ends with a function parameter pack.
4820 static bool isVariadicFunctionTemplate(FunctionTemplateDecl *FunTmpl) {
4821 FunctionDecl *Function = FunTmpl->getTemplatedDecl();
4822 unsigned NumParams = Function->getNumParams();
4826 ParmVarDecl *Last = Function->getParamDecl(NumParams - 1);
4827 if (!Last->isParameterPack())
4830 // Make sure that no previous parameter is a parameter pack.
4831 while (--NumParams > 0) {
4832 if (Function->getParamDecl(NumParams - 1)->isParameterPack())
4839 /// Returns the more specialized function template according
4840 /// to the rules of function template partial ordering (C++ [temp.func.order]).
4842 /// \param FT1 the first function template
4844 /// \param FT2 the second function template
4846 /// \param TPOC the context in which we are performing partial ordering of
4847 /// function templates.
4849 /// \param NumCallArguments1 The number of arguments in the call to FT1, used
4850 /// only when \c TPOC is \c TPOC_Call.
4852 /// \param NumCallArguments2 The number of arguments in the call to FT2, used
4853 /// only when \c TPOC is \c TPOC_Call.
4855 /// \returns the more specialized function template. If neither
4856 /// template is more specialized, returns NULL.
4857 FunctionTemplateDecl *
4858 Sema::getMoreSpecializedTemplate(FunctionTemplateDecl *FT1,
4859 FunctionTemplateDecl *FT2,
4861 TemplatePartialOrderingContext TPOC,
4862 unsigned NumCallArguments1,
4863 unsigned NumCallArguments2) {
4864 bool Better1 = isAtLeastAsSpecializedAs(*this, Loc, FT1, FT2, TPOC,
4866 bool Better2 = isAtLeastAsSpecializedAs(*this, Loc, FT2, FT1, TPOC,
4869 if (Better1 != Better2) // We have a clear winner
4870 return Better1 ? FT1 : FT2;
4872 if (!Better1 && !Better2) // Neither is better than the other
4875 // FIXME: This mimics what GCC implements, but doesn't match up with the
4876 // proposed resolution for core issue 692. This area needs to be sorted out,
4877 // but for now we attempt to maintain compatibility.
4878 bool Variadic1 = isVariadicFunctionTemplate(FT1);
4879 bool Variadic2 = isVariadicFunctionTemplate(FT2);
4880 if (Variadic1 != Variadic2)
4881 return Variadic1? FT2 : FT1;
4886 /// Determine if the two templates are equivalent.
4887 static bool isSameTemplate(TemplateDecl *T1, TemplateDecl *T2) {
4894 return T1->getCanonicalDecl() == T2->getCanonicalDecl();
4897 /// Retrieve the most specialized of the given function template
4898 /// specializations.
4900 /// \param SpecBegin the start iterator of the function template
4901 /// specializations that we will be comparing.
4903 /// \param SpecEnd the end iterator of the function template
4904 /// specializations, paired with \p SpecBegin.
4906 /// \param Loc the location where the ambiguity or no-specializations
4907 /// diagnostic should occur.
4909 /// \param NoneDiag partial diagnostic used to diagnose cases where there are
4910 /// no matching candidates.
4912 /// \param AmbigDiag partial diagnostic used to diagnose an ambiguity, if one
4915 /// \param CandidateDiag partial diagnostic used for each function template
4916 /// specialization that is a candidate in the ambiguous ordering. One parameter
4917 /// in this diagnostic should be unbound, which will correspond to the string
4918 /// describing the template arguments for the function template specialization.
4920 /// \returns the most specialized function template specialization, if
4921 /// found. Otherwise, returns SpecEnd.
4922 UnresolvedSetIterator Sema::getMostSpecialized(
4923 UnresolvedSetIterator SpecBegin, UnresolvedSetIterator SpecEnd,
4924 TemplateSpecCandidateSet &FailedCandidates,
4925 SourceLocation Loc, const PartialDiagnostic &NoneDiag,
4926 const PartialDiagnostic &AmbigDiag, const PartialDiagnostic &CandidateDiag,
4927 bool Complain, QualType TargetType) {
4928 if (SpecBegin == SpecEnd) {
4930 Diag(Loc, NoneDiag);
4931 FailedCandidates.NoteCandidates(*this, Loc);
4936 if (SpecBegin + 1 == SpecEnd)
4939 // Find the function template that is better than all of the templates it
4940 // has been compared to.
4941 UnresolvedSetIterator Best = SpecBegin;
4942 FunctionTemplateDecl *BestTemplate
4943 = cast<FunctionDecl>(*Best)->getPrimaryTemplate();
4944 assert(BestTemplate && "Not a function template specialization?");
4945 for (UnresolvedSetIterator I = SpecBegin + 1; I != SpecEnd; ++I) {
4946 FunctionTemplateDecl *Challenger
4947 = cast<FunctionDecl>(*I)->getPrimaryTemplate();
4948 assert(Challenger && "Not a function template specialization?");
4949 if (isSameTemplate(getMoreSpecializedTemplate(BestTemplate, Challenger,
4950 Loc, TPOC_Other, 0, 0),
4953 BestTemplate = Challenger;
4957 // Make sure that the "best" function template is more specialized than all
4959 bool Ambiguous = false;
4960 for (UnresolvedSetIterator I = SpecBegin; I != SpecEnd; ++I) {
4961 FunctionTemplateDecl *Challenger
4962 = cast<FunctionDecl>(*I)->getPrimaryTemplate();
4964 !isSameTemplate(getMoreSpecializedTemplate(BestTemplate, Challenger,
4965 Loc, TPOC_Other, 0, 0),
4973 // We found an answer. Return it.
4977 // Diagnose the ambiguity.
4979 Diag(Loc, AmbigDiag);
4981 // FIXME: Can we order the candidates in some sane way?
4982 for (UnresolvedSetIterator I = SpecBegin; I != SpecEnd; ++I) {
4983 PartialDiagnostic PD = CandidateDiag;
4984 const auto *FD = cast<FunctionDecl>(*I);
4985 PD << FD << getTemplateArgumentBindingsText(
4986 FD->getPrimaryTemplate()->getTemplateParameters(),
4987 *FD->getTemplateSpecializationArgs());
4988 if (!TargetType.isNull())
4989 HandleFunctionTypeMismatch(PD, FD->getType(), TargetType);
4990 Diag((*I)->getLocation(), PD);
4997 /// Determine whether one partial specialization, P1, is at least as
4998 /// specialized than another, P2.
5000 /// \tparam TemplateLikeDecl The kind of P2, which must be a
5001 /// TemplateDecl or {Class,Var}TemplatePartialSpecializationDecl.
5002 /// \param T1 The injected-class-name of P1 (faked for a variable template).
5003 /// \param T2 The injected-class-name of P2 (faked for a variable template).
5004 template<typename TemplateLikeDecl>
5005 static bool isAtLeastAsSpecializedAs(Sema &S, QualType T1, QualType T2,
5006 TemplateLikeDecl *P2,
5007 TemplateDeductionInfo &Info) {
5008 // C++ [temp.class.order]p1:
5009 // For two class template partial specializations, the first is at least as
5010 // specialized as the second if, given the following rewrite to two
5011 // function templates, the first function template is at least as
5012 // specialized as the second according to the ordering rules for function
5013 // templates (14.6.6.2):
5014 // - the first function template has the same template parameters as the
5015 // first partial specialization and has a single function parameter
5016 // whose type is a class template specialization with the template
5017 // arguments of the first partial specialization, and
5018 // - the second function template has the same template parameters as the
5019 // second partial specialization and has a single function parameter
5020 // whose type is a class template specialization with the template
5021 // arguments of the second partial specialization.
5023 // Rather than synthesize function templates, we merely perform the
5024 // equivalent partial ordering by performing deduction directly on
5025 // the template arguments of the class template partial
5026 // specializations. This computation is slightly simpler than the
5027 // general problem of function template partial ordering, because
5028 // class template partial specializations are more constrained. We
5029 // know that every template parameter is deducible from the class
5030 // template partial specialization's template arguments, for
5032 SmallVector<DeducedTemplateArgument, 4> Deduced;
5034 // Determine whether P1 is at least as specialized as P2.
5035 Deduced.resize(P2->getTemplateParameters()->size());
5036 if (DeduceTemplateArgumentsByTypeMatch(S, P2->getTemplateParameters(),
5037 T2, T1, Info, Deduced, TDF_None,
5038 /*PartialOrdering=*/true))
5041 SmallVector<TemplateArgument, 4> DeducedArgs(Deduced.begin(),
5043 Sema::InstantiatingTemplate Inst(S, Info.getLocation(), P2, DeducedArgs,
5045 auto *TST1 = T1->castAs<TemplateSpecializationType>();
5046 if (FinishTemplateArgumentDeduction(
5047 S, P2, /*PartialOrdering=*/true,
5048 TemplateArgumentList(TemplateArgumentList::OnStack,
5049 TST1->template_arguments()),
5056 /// Returns the more specialized class template partial specialization
5057 /// according to the rules of partial ordering of class template partial
5058 /// specializations (C++ [temp.class.order]).
5060 /// \param PS1 the first class template partial specialization
5062 /// \param PS2 the second class template partial specialization
5064 /// \returns the more specialized class template partial specialization. If
5065 /// neither partial specialization is more specialized, returns NULL.
5066 ClassTemplatePartialSpecializationDecl *
5067 Sema::getMoreSpecializedPartialSpecialization(
5068 ClassTemplatePartialSpecializationDecl *PS1,
5069 ClassTemplatePartialSpecializationDecl *PS2,
5070 SourceLocation Loc) {
5071 QualType PT1 = PS1->getInjectedSpecializationType();
5072 QualType PT2 = PS2->getInjectedSpecializationType();
5074 TemplateDeductionInfo Info(Loc);
5075 bool Better1 = isAtLeastAsSpecializedAs(*this, PT1, PT2, PS2, Info);
5076 bool Better2 = isAtLeastAsSpecializedAs(*this, PT2, PT1, PS1, Info);
5078 if (Better1 == Better2)
5081 return Better1 ? PS1 : PS2;
5084 bool Sema::isMoreSpecializedThanPrimary(
5085 ClassTemplatePartialSpecializationDecl *Spec, TemplateDeductionInfo &Info) {
5086 ClassTemplateDecl *Primary = Spec->getSpecializedTemplate();
5087 QualType PrimaryT = Primary->getInjectedClassNameSpecialization();
5088 QualType PartialT = Spec->getInjectedSpecializationType();
5089 if (!isAtLeastAsSpecializedAs(*this, PartialT, PrimaryT, Primary, Info))
5091 if (isAtLeastAsSpecializedAs(*this, PrimaryT, PartialT, Spec, Info)) {
5092 Info.clearSFINAEDiagnostic();
5098 VarTemplatePartialSpecializationDecl *
5099 Sema::getMoreSpecializedPartialSpecialization(
5100 VarTemplatePartialSpecializationDecl *PS1,
5101 VarTemplatePartialSpecializationDecl *PS2, SourceLocation Loc) {
5102 // Pretend the variable template specializations are class template
5103 // specializations and form a fake injected class name type for comparison.
5104 assert(PS1->getSpecializedTemplate() == PS2->getSpecializedTemplate() &&
5105 "the partial specializations being compared should specialize"
5106 " the same template.");
5107 TemplateName Name(PS1->getSpecializedTemplate());
5108 TemplateName CanonTemplate = Context.getCanonicalTemplateName(Name);
5109 QualType PT1 = Context.getTemplateSpecializationType(
5110 CanonTemplate, PS1->getTemplateArgs().asArray());
5111 QualType PT2 = Context.getTemplateSpecializationType(
5112 CanonTemplate, PS2->getTemplateArgs().asArray());
5114 TemplateDeductionInfo Info(Loc);
5115 bool Better1 = isAtLeastAsSpecializedAs(*this, PT1, PT2, PS2, Info);
5116 bool Better2 = isAtLeastAsSpecializedAs(*this, PT2, PT1, PS1, Info);
5118 if (Better1 == Better2)
5121 return Better1 ? PS1 : PS2;
5124 bool Sema::isMoreSpecializedThanPrimary(
5125 VarTemplatePartialSpecializationDecl *Spec, TemplateDeductionInfo &Info) {
5126 TemplateDecl *Primary = Spec->getSpecializedTemplate();
5127 // FIXME: Cache the injected template arguments rather than recomputing
5128 // them for each partial specialization.
5129 SmallVector<TemplateArgument, 8> PrimaryArgs;
5130 Context.getInjectedTemplateArgs(Primary->getTemplateParameters(),
5133 TemplateName CanonTemplate =
5134 Context.getCanonicalTemplateName(TemplateName(Primary));
5135 QualType PrimaryT = Context.getTemplateSpecializationType(
5136 CanonTemplate, PrimaryArgs);
5137 QualType PartialT = Context.getTemplateSpecializationType(
5138 CanonTemplate, Spec->getTemplateArgs().asArray());
5139 if (!isAtLeastAsSpecializedAs(*this, PartialT, PrimaryT, Primary, Info))
5141 if (isAtLeastAsSpecializedAs(*this, PrimaryT, PartialT, Spec, Info)) {
5142 Info.clearSFINAEDiagnostic();
5148 bool Sema::isTemplateTemplateParameterAtLeastAsSpecializedAs(
5149 TemplateParameterList *P, TemplateDecl *AArg, SourceLocation Loc) {
5150 // C++1z [temp.arg.template]p4: (DR 150)
5151 // A template template-parameter P is at least as specialized as a
5152 // template template-argument A if, given the following rewrite to two
5153 // function templates...
5155 // Rather than synthesize function templates, we merely perform the
5156 // equivalent partial ordering by performing deduction directly on
5157 // the template parameter lists of the template template parameters.
5159 // Given an invented class template X with the template parameter list of
5160 // A (including default arguments):
5161 TemplateName X = Context.getCanonicalTemplateName(TemplateName(AArg));
5162 TemplateParameterList *A = AArg->getTemplateParameters();
5164 // - Each function template has a single function parameter whose type is
5165 // a specialization of X with template arguments corresponding to the
5166 // template parameters from the respective function template
5167 SmallVector<TemplateArgument, 8> AArgs;
5168 Context.getInjectedTemplateArgs(A, AArgs);
5170 // Check P's arguments against A's parameter list. This will fill in default
5171 // template arguments as needed. AArgs are already correct by construction.
5172 // We can't just use CheckTemplateIdType because that will expand alias
5174 SmallVector<TemplateArgument, 4> PArgs;
5176 SFINAETrap Trap(*this);
5178 Context.getInjectedTemplateArgs(P, PArgs);
5179 TemplateArgumentListInfo PArgList(P->getLAngleLoc(), P->getRAngleLoc());
5180 for (unsigned I = 0, N = P->size(); I != N; ++I) {
5181 // Unwrap packs that getInjectedTemplateArgs wrapped around pack
5182 // expansions, to form an "as written" argument list.
5183 TemplateArgument Arg = PArgs[I];
5184 if (Arg.getKind() == TemplateArgument::Pack) {
5185 assert(Arg.pack_size() == 1 && Arg.pack_begin()->isPackExpansion());
5186 Arg = *Arg.pack_begin();
5188 PArgList.addArgument(getTrivialTemplateArgumentLoc(
5189 Arg, QualType(), P->getParam(I)->getLocation()));
5193 // C++1z [temp.arg.template]p3:
5194 // If the rewrite produces an invalid type, then P is not at least as
5195 // specialized as A.
5196 if (CheckTemplateArgumentList(AArg, Loc, PArgList, false, PArgs) ||
5197 Trap.hasErrorOccurred())
5201 QualType AType = Context.getTemplateSpecializationType(X, AArgs);
5202 QualType PType = Context.getTemplateSpecializationType(X, PArgs);
5204 // ... the function template corresponding to P is at least as specialized
5205 // as the function template corresponding to A according to the partial
5206 // ordering rules for function templates.
5207 TemplateDeductionInfo Info(Loc, A->getDepth());
5208 return isAtLeastAsSpecializedAs(*this, PType, AType, AArg, Info);
5211 /// Mark the template parameters that are used by the given
5214 MarkUsedTemplateParameters(ASTContext &Ctx,
5218 llvm::SmallBitVector &Used) {
5219 // We can deduce from a pack expansion.
5220 if (const PackExpansionExpr *Expansion = dyn_cast<PackExpansionExpr>(E))
5221 E = Expansion->getPattern();
5223 // Skip through any implicit casts we added while type-checking, and any
5224 // substitutions performed by template alias expansion.
5226 if (const ImplicitCastExpr *ICE = dyn_cast<ImplicitCastExpr>(E))
5227 E = ICE->getSubExpr();
5228 else if (const SubstNonTypeTemplateParmExpr *Subst =
5229 dyn_cast<SubstNonTypeTemplateParmExpr>(E))
5230 E = Subst->getReplacement();
5235 // FIXME: if !OnlyDeduced, we have to walk the whole subexpression to
5236 // find other occurrences of template parameters.
5237 const DeclRefExpr *DRE = dyn_cast<DeclRefExpr>(E);
5241 const NonTypeTemplateParmDecl *NTTP
5242 = dyn_cast<NonTypeTemplateParmDecl>(DRE->getDecl());
5246 if (NTTP->getDepth() == Depth)
5247 Used[NTTP->getIndex()] = true;
5249 // In C++17 mode, additional arguments may be deduced from the type of a
5250 // non-type argument.
5251 if (Ctx.getLangOpts().CPlusPlus17)
5252 MarkUsedTemplateParameters(Ctx, NTTP->getType(), OnlyDeduced, Depth, Used);
5255 /// Mark the template parameters that are used by the given
5256 /// nested name specifier.
5258 MarkUsedTemplateParameters(ASTContext &Ctx,
5259 NestedNameSpecifier *NNS,
5262 llvm::SmallBitVector &Used) {
5266 MarkUsedTemplateParameters(Ctx, NNS->getPrefix(), OnlyDeduced, Depth,
5268 MarkUsedTemplateParameters(Ctx, QualType(NNS->getAsType(), 0),
5269 OnlyDeduced, Depth, Used);
5272 /// Mark the template parameters that are used by the given
5275 MarkUsedTemplateParameters(ASTContext &Ctx,
5279 llvm::SmallBitVector &Used) {
5280 if (TemplateDecl *Template = Name.getAsTemplateDecl()) {
5281 if (TemplateTemplateParmDecl *TTP
5282 = dyn_cast<TemplateTemplateParmDecl>(Template)) {
5283 if (TTP->getDepth() == Depth)
5284 Used[TTP->getIndex()] = true;
5289 if (QualifiedTemplateName *QTN = Name.getAsQualifiedTemplateName())
5290 MarkUsedTemplateParameters(Ctx, QTN->getQualifier(), OnlyDeduced,
5292 if (DependentTemplateName *DTN = Name.getAsDependentTemplateName())
5293 MarkUsedTemplateParameters(Ctx, DTN->getQualifier(), OnlyDeduced,
5297 /// Mark the template parameters that are used by the given
5300 MarkUsedTemplateParameters(ASTContext &Ctx, QualType T,
5303 llvm::SmallBitVector &Used) {
5307 // Non-dependent types have nothing deducible
5308 if (!T->isDependentType())
5311 T = Ctx.getCanonicalType(T);
5312 switch (T->getTypeClass()) {
5314 MarkUsedTemplateParameters(Ctx,
5315 cast<PointerType>(T)->getPointeeType(),
5321 case Type::BlockPointer:
5322 MarkUsedTemplateParameters(Ctx,
5323 cast<BlockPointerType>(T)->getPointeeType(),
5329 case Type::LValueReference:
5330 case Type::RValueReference:
5331 MarkUsedTemplateParameters(Ctx,
5332 cast<ReferenceType>(T)->getPointeeType(),
5338 case Type::MemberPointer: {
5339 const MemberPointerType *MemPtr = cast<MemberPointerType>(T.getTypePtr());
5340 MarkUsedTemplateParameters(Ctx, MemPtr->getPointeeType(), OnlyDeduced,
5342 MarkUsedTemplateParameters(Ctx, QualType(MemPtr->getClass(), 0),
5343 OnlyDeduced, Depth, Used);
5347 case Type::DependentSizedArray:
5348 MarkUsedTemplateParameters(Ctx,
5349 cast<DependentSizedArrayType>(T)->getSizeExpr(),
5350 OnlyDeduced, Depth, Used);
5351 // Fall through to check the element type
5354 case Type::ConstantArray:
5355 case Type::IncompleteArray:
5356 MarkUsedTemplateParameters(Ctx,
5357 cast<ArrayType>(T)->getElementType(),
5358 OnlyDeduced, Depth, Used);
5362 case Type::ExtVector:
5363 MarkUsedTemplateParameters(Ctx,
5364 cast<VectorType>(T)->getElementType(),
5365 OnlyDeduced, Depth, Used);
5368 case Type::DependentVector: {
5369 const auto *VecType = cast<DependentVectorType>(T);
5370 MarkUsedTemplateParameters(Ctx, VecType->getElementType(), OnlyDeduced,
5372 MarkUsedTemplateParameters(Ctx, VecType->getSizeExpr(), OnlyDeduced, Depth,
5376 case Type::DependentSizedExtVector: {
5377 const DependentSizedExtVectorType *VecType
5378 = cast<DependentSizedExtVectorType>(T);
5379 MarkUsedTemplateParameters(Ctx, VecType->getElementType(), OnlyDeduced,
5381 MarkUsedTemplateParameters(Ctx, VecType->getSizeExpr(), OnlyDeduced,
5386 case Type::DependentAddressSpace: {
5387 const DependentAddressSpaceType *DependentASType =
5388 cast<DependentAddressSpaceType>(T);
5389 MarkUsedTemplateParameters(Ctx, DependentASType->getPointeeType(),
5390 OnlyDeduced, Depth, Used);
5391 MarkUsedTemplateParameters(Ctx,
5392 DependentASType->getAddrSpaceExpr(),
5393 OnlyDeduced, Depth, Used);
5397 case Type::FunctionProto: {
5398 const FunctionProtoType *Proto = cast<FunctionProtoType>(T);
5399 MarkUsedTemplateParameters(Ctx, Proto->getReturnType(), OnlyDeduced, Depth,
5401 for (unsigned I = 0, N = Proto->getNumParams(); I != N; ++I) {
5402 // C++17 [temp.deduct.type]p5:
5403 // The non-deduced contexts are: [...]
5404 // -- A function parameter pack that does not occur at the end of the
5405 // parameter-declaration-list.
5406 if (!OnlyDeduced || I + 1 == N ||
5407 !Proto->getParamType(I)->getAs<PackExpansionType>()) {
5408 MarkUsedTemplateParameters(Ctx, Proto->getParamType(I), OnlyDeduced,
5411 // FIXME: C++17 [temp.deduct.call]p1:
5412 // When a function parameter pack appears in a non-deduced context,
5413 // the type of that pack is never deduced.
5415 // We should also track a set of "never deduced" parameters, and
5416 // subtract that from the list of deduced parameters after marking.
5419 if (auto *E = Proto->getNoexceptExpr())
5420 MarkUsedTemplateParameters(Ctx, E, OnlyDeduced, Depth, Used);
5424 case Type::TemplateTypeParm: {
5425 const TemplateTypeParmType *TTP = cast<TemplateTypeParmType>(T);
5426 if (TTP->getDepth() == Depth)
5427 Used[TTP->getIndex()] = true;
5431 case Type::SubstTemplateTypeParmPack: {
5432 const SubstTemplateTypeParmPackType *Subst
5433 = cast<SubstTemplateTypeParmPackType>(T);
5434 MarkUsedTemplateParameters(Ctx,
5435 QualType(Subst->getReplacedParameter(), 0),
5436 OnlyDeduced, Depth, Used);
5437 MarkUsedTemplateParameters(Ctx, Subst->getArgumentPack(),
5438 OnlyDeduced, Depth, Used);
5442 case Type::InjectedClassName:
5443 T = cast<InjectedClassNameType>(T)->getInjectedSpecializationType();
5446 case Type::TemplateSpecialization: {
5447 const TemplateSpecializationType *Spec
5448 = cast<TemplateSpecializationType>(T);
5449 MarkUsedTemplateParameters(Ctx, Spec->getTemplateName(), OnlyDeduced,
5452 // C++0x [temp.deduct.type]p9:
5453 // If the template argument list of P contains a pack expansion that is
5454 // not the last template argument, the entire template argument list is a
5455 // non-deduced context.
5457 hasPackExpansionBeforeEnd(Spec->template_arguments()))
5460 for (unsigned I = 0, N = Spec->getNumArgs(); I != N; ++I)
5461 MarkUsedTemplateParameters(Ctx, Spec->getArg(I), OnlyDeduced, Depth,
5468 MarkUsedTemplateParameters(Ctx,
5469 cast<ComplexType>(T)->getElementType(),
5470 OnlyDeduced, Depth, Used);
5475 MarkUsedTemplateParameters(Ctx,
5476 cast<AtomicType>(T)->getValueType(),
5477 OnlyDeduced, Depth, Used);
5480 case Type::DependentName:
5482 MarkUsedTemplateParameters(Ctx,
5483 cast<DependentNameType>(T)->getQualifier(),
5484 OnlyDeduced, Depth, Used);
5487 case Type::DependentTemplateSpecialization: {
5488 // C++14 [temp.deduct.type]p5:
5489 // The non-deduced contexts are:
5490 // -- The nested-name-specifier of a type that was specified using a
5493 // C++14 [temp.deduct.type]p6:
5494 // When a type name is specified in a way that includes a non-deduced
5495 // context, all of the types that comprise that type name are also
5500 const DependentTemplateSpecializationType *Spec
5501 = cast<DependentTemplateSpecializationType>(T);
5503 MarkUsedTemplateParameters(Ctx, Spec->getQualifier(),
5504 OnlyDeduced, Depth, Used);
5506 for (unsigned I = 0, N = Spec->getNumArgs(); I != N; ++I)
5507 MarkUsedTemplateParameters(Ctx, Spec->getArg(I), OnlyDeduced, Depth,
5514 MarkUsedTemplateParameters(Ctx,
5515 cast<TypeOfType>(T)->getUnderlyingType(),
5516 OnlyDeduced, Depth, Used);
5519 case Type::TypeOfExpr:
5521 MarkUsedTemplateParameters(Ctx,
5522 cast<TypeOfExprType>(T)->getUnderlyingExpr(),
5523 OnlyDeduced, Depth, Used);
5526 case Type::Decltype:
5528 MarkUsedTemplateParameters(Ctx,
5529 cast<DecltypeType>(T)->getUnderlyingExpr(),
5530 OnlyDeduced, Depth, Used);
5533 case Type::UnaryTransform:
5535 MarkUsedTemplateParameters(Ctx,
5536 cast<UnaryTransformType>(T)->getUnderlyingType(),
5537 OnlyDeduced, Depth, Used);
5540 case Type::PackExpansion:
5541 MarkUsedTemplateParameters(Ctx,
5542 cast<PackExpansionType>(T)->getPattern(),
5543 OnlyDeduced, Depth, Used);
5547 case Type::DeducedTemplateSpecialization:
5548 MarkUsedTemplateParameters(Ctx,
5549 cast<DeducedType>(T)->getDeducedType(),
5550 OnlyDeduced, Depth, Used);
5553 // None of these types have any template parameters in them.
5555 case Type::VariableArray:
5556 case Type::FunctionNoProto:
5559 case Type::ObjCInterface:
5560 case Type::ObjCObject:
5561 case Type::ObjCObjectPointer:
5562 case Type::UnresolvedUsing:
5564 #define TYPE(Class, Base)
5565 #define ABSTRACT_TYPE(Class, Base)
5566 #define DEPENDENT_TYPE(Class, Base)
5567 #define NON_CANONICAL_TYPE(Class, Base) case Type::Class:
5568 #include "clang/AST/TypeNodes.def"
5573 /// Mark the template parameters that are used by this
5574 /// template argument.
5576 MarkUsedTemplateParameters(ASTContext &Ctx,
5577 const TemplateArgument &TemplateArg,
5580 llvm::SmallBitVector &Used) {
5581 switch (TemplateArg.getKind()) {
5582 case TemplateArgument::Null:
5583 case TemplateArgument::Integral:
5584 case TemplateArgument::Declaration:
5587 case TemplateArgument::NullPtr:
5588 MarkUsedTemplateParameters(Ctx, TemplateArg.getNullPtrType(), OnlyDeduced,
5592 case TemplateArgument::Type:
5593 MarkUsedTemplateParameters(Ctx, TemplateArg.getAsType(), OnlyDeduced,
5597 case TemplateArgument::Template:
5598 case TemplateArgument::TemplateExpansion:
5599 MarkUsedTemplateParameters(Ctx,
5600 TemplateArg.getAsTemplateOrTemplatePattern(),
5601 OnlyDeduced, Depth, Used);
5604 case TemplateArgument::Expression:
5605 MarkUsedTemplateParameters(Ctx, TemplateArg.getAsExpr(), OnlyDeduced,
5609 case TemplateArgument::Pack:
5610 for (const auto &P : TemplateArg.pack_elements())
5611 MarkUsedTemplateParameters(Ctx, P, OnlyDeduced, Depth, Used);
5616 /// Mark which template parameters can be deduced from a given
5617 /// template argument list.
5619 /// \param TemplateArgs the template argument list from which template
5620 /// parameters will be deduced.
5622 /// \param Used a bit vector whose elements will be set to \c true
5623 /// to indicate when the corresponding template parameter will be
5626 Sema::MarkUsedTemplateParameters(const TemplateArgumentList &TemplateArgs,
5627 bool OnlyDeduced, unsigned Depth,
5628 llvm::SmallBitVector &Used) {
5629 // C++0x [temp.deduct.type]p9:
5630 // If the template argument list of P contains a pack expansion that is not
5631 // the last template argument, the entire template argument list is a
5632 // non-deduced context.
5634 hasPackExpansionBeforeEnd(TemplateArgs.asArray()))
5637 for (unsigned I = 0, N = TemplateArgs.size(); I != N; ++I)
5638 ::MarkUsedTemplateParameters(Context, TemplateArgs[I], OnlyDeduced,
5642 /// Marks all of the template parameters that will be deduced by a
5643 /// call to the given function template.
5644 void Sema::MarkDeducedTemplateParameters(
5645 ASTContext &Ctx, const FunctionTemplateDecl *FunctionTemplate,
5646 llvm::SmallBitVector &Deduced) {
5647 TemplateParameterList *TemplateParams
5648 = FunctionTemplate->getTemplateParameters();
5650 Deduced.resize(TemplateParams->size());
5652 FunctionDecl *Function = FunctionTemplate->getTemplatedDecl();
5653 for (unsigned I = 0, N = Function->getNumParams(); I != N; ++I)
5654 ::MarkUsedTemplateParameters(Ctx, Function->getParamDecl(I)->getType(),
5655 true, TemplateParams->getDepth(), Deduced);
5658 bool hasDeducibleTemplateParameters(Sema &S,
5659 FunctionTemplateDecl *FunctionTemplate,
5661 if (!T->isDependentType())
5664 TemplateParameterList *TemplateParams
5665 = FunctionTemplate->getTemplateParameters();
5666 llvm::SmallBitVector Deduced(TemplateParams->size());
5667 ::MarkUsedTemplateParameters(S.Context, T, true, TemplateParams->getDepth(),
5670 return Deduced.any();