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.
7 //===----------------------------------------------------------------------===/
9 // This file implements C++ template argument deduction.
11 //===----------------------------------------------------------------------===/
13 #include "clang/Sema/TemplateDeduction.h"
14 #include "TreeTransform.h"
15 #include "clang/AST/ASTContext.h"
16 #include "clang/AST/ASTLambda.h"
17 #include "clang/AST/DeclObjC.h"
18 #include "clang/AST/DeclTemplate.h"
19 #include "clang/AST/Expr.h"
20 #include "clang/AST/ExprCXX.h"
21 #include "clang/AST/StmtVisitor.h"
22 #include "clang/AST/TypeOrdering.h"
23 #include "clang/Sema/DeclSpec.h"
24 #include "clang/Sema/Sema.h"
25 #include "clang/Sema/Template.h"
26 #include "llvm/ADT/SmallBitVector.h"
31 /// \brief Various flags that control template argument deduction.
33 /// These flags can be bitwise-OR'd together.
34 enum TemplateDeductionFlags {
35 /// \brief No template argument deduction flags, which indicates the
36 /// strictest results for template argument deduction (as used for, e.g.,
37 /// matching class template partial specializations).
39 /// \brief Within template argument deduction from a function call, we are
40 /// matching with a parameter type for which the original parameter was
42 TDF_ParamWithReferenceType = 0x1,
43 /// \brief Within template argument deduction from a function call, we
44 /// are matching in a case where we ignore cv-qualifiers.
45 TDF_IgnoreQualifiers = 0x02,
46 /// \brief Within template argument deduction from a function call,
47 /// we are matching in a case where we can perform template argument
48 /// deduction from a template-id of a derived class of the argument type.
49 TDF_DerivedClass = 0x04,
50 /// \brief Allow non-dependent types to differ, e.g., when performing
51 /// template argument deduction from a function call where conversions
53 TDF_SkipNonDependent = 0x08,
54 /// \brief Whether we are performing template argument deduction for
55 /// parameters and arguments in a top-level template argument
56 TDF_TopLevelParameterTypeList = 0x10,
57 /// \brief Within template argument deduction from overload resolution per
58 /// C++ [over.over] allow matching function types that are compatible in
59 /// terms of noreturn and default calling convention adjustments, or
60 /// similarly matching a declared template specialization against a
61 /// possible template, per C++ [temp.deduct.decl]. In either case, permit
62 /// deduction where the parameter is a function type that can be converted
63 /// to the argument type.
64 TDF_AllowCompatibleFunctionType = 0x20,
68 using namespace clang;
70 /// \brief Compare two APSInts, extending and switching the sign as
71 /// necessary to compare their values regardless of underlying type.
72 static bool hasSameExtendedValue(llvm::APSInt X, llvm::APSInt Y) {
73 if (Y.getBitWidth() > X.getBitWidth())
74 X = X.extend(Y.getBitWidth());
75 else if (Y.getBitWidth() < X.getBitWidth())
76 Y = Y.extend(X.getBitWidth());
78 // If there is a signedness mismatch, correct it.
79 if (X.isSigned() != Y.isSigned()) {
80 // If the signed value is negative, then the values cannot be the same.
81 if ((Y.isSigned() && Y.isNegative()) || (X.isSigned() && X.isNegative()))
91 static Sema::TemplateDeductionResult
92 DeduceTemplateArguments(Sema &S,
93 TemplateParameterList *TemplateParams,
94 const TemplateArgument &Param,
96 TemplateDeductionInfo &Info,
97 SmallVectorImpl<DeducedTemplateArgument> &Deduced);
99 static Sema::TemplateDeductionResult
100 DeduceTemplateArgumentsByTypeMatch(Sema &S,
101 TemplateParameterList *TemplateParams,
104 TemplateDeductionInfo &Info,
105 SmallVectorImpl<DeducedTemplateArgument> &
108 bool PartialOrdering = false,
109 bool DeducedFromArrayBound = false);
111 static Sema::TemplateDeductionResult
112 DeduceTemplateArguments(Sema &S, TemplateParameterList *TemplateParams,
113 ArrayRef<TemplateArgument> Params,
114 ArrayRef<TemplateArgument> Args,
115 TemplateDeductionInfo &Info,
116 SmallVectorImpl<DeducedTemplateArgument> &Deduced,
117 bool NumberOfArgumentsMustMatch);
119 static void MarkUsedTemplateParameters(ASTContext &Ctx,
120 const TemplateArgument &TemplateArg,
121 bool OnlyDeduced, unsigned Depth,
122 llvm::SmallBitVector &Used);
124 static void MarkUsedTemplateParameters(ASTContext &Ctx, QualType T,
125 bool OnlyDeduced, unsigned Level,
126 llvm::SmallBitVector &Deduced);
128 /// \brief If the given expression is of a form that permits the deduction
129 /// of a non-type template parameter, return the declaration of that
130 /// non-type template parameter.
131 static NonTypeTemplateParmDecl *
132 getDeducedParameterFromExpr(TemplateDeductionInfo &Info, Expr *E) {
133 // If we are within an alias template, the expression may have undergone
134 // any number of parameter substitutions already.
136 if (ImplicitCastExpr *IC = dyn_cast<ImplicitCastExpr>(E))
137 E = IC->getSubExpr();
138 else if (SubstNonTypeTemplateParmExpr *Subst =
139 dyn_cast<SubstNonTypeTemplateParmExpr>(E))
140 E = Subst->getReplacement();
145 if (DeclRefExpr *DRE = dyn_cast<DeclRefExpr>(E))
146 if (auto *NTTP = dyn_cast<NonTypeTemplateParmDecl>(DRE->getDecl()))
147 if (NTTP->getDepth() == Info.getDeducedDepth())
153 /// \brief Determine whether two declaration pointers refer to the same
155 static bool isSameDeclaration(Decl *X, Decl *Y) {
156 if (NamedDecl *NX = dyn_cast<NamedDecl>(X))
157 X = NX->getUnderlyingDecl();
158 if (NamedDecl *NY = dyn_cast<NamedDecl>(Y))
159 Y = NY->getUnderlyingDecl();
161 return X->getCanonicalDecl() == Y->getCanonicalDecl();
164 /// \brief Verify that the given, deduced template arguments are compatible.
166 /// \returns The deduced template argument, or a NULL template argument if
167 /// the deduced template arguments were incompatible.
168 static DeducedTemplateArgument
169 checkDeducedTemplateArguments(ASTContext &Context,
170 const DeducedTemplateArgument &X,
171 const DeducedTemplateArgument &Y) {
172 // We have no deduction for one or both of the arguments; they're compatible.
178 // If we have two non-type template argument values deduced for the same
179 // parameter, they must both match the type of the parameter, and thus must
180 // match each other's type. As we're only keeping one of them, we must check
181 // for that now. The exception is that if either was deduced from an array
182 // bound, the type is permitted to differ.
183 if (!X.wasDeducedFromArrayBound() && !Y.wasDeducedFromArrayBound()) {
184 QualType XType = X.getNonTypeTemplateArgumentType();
185 if (!XType.isNull()) {
186 QualType YType = Y.getNonTypeTemplateArgumentType();
187 if (YType.isNull() || !Context.hasSameType(XType, YType))
188 return DeducedTemplateArgument();
192 switch (X.getKind()) {
193 case TemplateArgument::Null:
194 llvm_unreachable("Non-deduced template arguments handled above");
196 case TemplateArgument::Type:
197 // If two template type arguments have the same type, they're compatible.
198 if (Y.getKind() == TemplateArgument::Type &&
199 Context.hasSameType(X.getAsType(), Y.getAsType()))
202 // If one of the two arguments was deduced from an array bound, the other
204 if (X.wasDeducedFromArrayBound() != Y.wasDeducedFromArrayBound())
205 return X.wasDeducedFromArrayBound() ? Y : X;
207 // The arguments are not compatible.
208 return DeducedTemplateArgument();
210 case TemplateArgument::Integral:
211 // If we deduced a constant in one case and either a dependent expression or
212 // declaration in another case, keep the integral constant.
213 // If both are integral constants with the same value, keep that value.
214 if (Y.getKind() == TemplateArgument::Expression ||
215 Y.getKind() == TemplateArgument::Declaration ||
216 (Y.getKind() == TemplateArgument::Integral &&
217 hasSameExtendedValue(X.getAsIntegral(), Y.getAsIntegral())))
218 return X.wasDeducedFromArrayBound() ? Y : X;
220 // All other combinations are incompatible.
221 return DeducedTemplateArgument();
223 case TemplateArgument::Template:
224 if (Y.getKind() == TemplateArgument::Template &&
225 Context.hasSameTemplateName(X.getAsTemplate(), Y.getAsTemplate()))
228 // All other combinations are incompatible.
229 return DeducedTemplateArgument();
231 case TemplateArgument::TemplateExpansion:
232 if (Y.getKind() == TemplateArgument::TemplateExpansion &&
233 Context.hasSameTemplateName(X.getAsTemplateOrTemplatePattern(),
234 Y.getAsTemplateOrTemplatePattern()))
237 // All other combinations are incompatible.
238 return DeducedTemplateArgument();
240 case TemplateArgument::Expression: {
241 if (Y.getKind() != TemplateArgument::Expression)
242 return checkDeducedTemplateArguments(Context, Y, X);
244 // Compare the expressions for equality
245 llvm::FoldingSetNodeID ID1, ID2;
246 X.getAsExpr()->Profile(ID1, Context, true);
247 Y.getAsExpr()->Profile(ID2, Context, true);
249 return X.wasDeducedFromArrayBound() ? Y : X;
251 // Differing dependent expressions are incompatible.
252 return DeducedTemplateArgument();
255 case TemplateArgument::Declaration:
256 assert(!X.wasDeducedFromArrayBound());
258 // If we deduced a declaration and a dependent expression, keep the
260 if (Y.getKind() == TemplateArgument::Expression)
263 // If we deduced a declaration and an integral constant, keep the
264 // integral constant and whichever type did not come from an array
266 if (Y.getKind() == TemplateArgument::Integral) {
267 if (Y.wasDeducedFromArrayBound())
268 return TemplateArgument(Context, Y.getAsIntegral(),
269 X.getParamTypeForDecl());
273 // If we deduced two declarations, make sure they they refer to the
275 if (Y.getKind() == TemplateArgument::Declaration &&
276 isSameDeclaration(X.getAsDecl(), Y.getAsDecl()))
279 // All other combinations are incompatible.
280 return DeducedTemplateArgument();
282 case TemplateArgument::NullPtr:
283 // If we deduced a null pointer and a dependent expression, keep the
285 if (Y.getKind() == TemplateArgument::Expression)
288 // If we deduced a null pointer and an integral constant, keep the
289 // integral constant.
290 if (Y.getKind() == TemplateArgument::Integral)
293 // If we deduced two null pointers, they are the same.
294 if (Y.getKind() == TemplateArgument::NullPtr)
297 // All other combinations are incompatible.
298 return DeducedTemplateArgument();
300 case TemplateArgument::Pack:
301 if (Y.getKind() != TemplateArgument::Pack ||
302 X.pack_size() != Y.pack_size())
303 return DeducedTemplateArgument();
305 llvm::SmallVector<TemplateArgument, 8> NewPack;
306 for (TemplateArgument::pack_iterator XA = X.pack_begin(),
307 XAEnd = X.pack_end(),
309 XA != XAEnd; ++XA, ++YA) {
310 TemplateArgument Merged = checkDeducedTemplateArguments(
311 Context, DeducedTemplateArgument(*XA, X.wasDeducedFromArrayBound()),
312 DeducedTemplateArgument(*YA, Y.wasDeducedFromArrayBound()));
314 return DeducedTemplateArgument();
315 NewPack.push_back(Merged);
318 return DeducedTemplateArgument(
319 TemplateArgument::CreatePackCopy(Context, NewPack),
320 X.wasDeducedFromArrayBound() && Y.wasDeducedFromArrayBound());
323 llvm_unreachable("Invalid TemplateArgument Kind!");
326 /// \brief Deduce the value of the given non-type template parameter
327 /// as the given deduced template argument. All non-type template parameter
328 /// deduction is funneled through here.
329 static Sema::TemplateDeductionResult DeduceNonTypeTemplateArgument(
330 Sema &S, TemplateParameterList *TemplateParams,
331 NonTypeTemplateParmDecl *NTTP, const DeducedTemplateArgument &NewDeduced,
332 QualType ValueType, TemplateDeductionInfo &Info,
333 SmallVectorImpl<DeducedTemplateArgument> &Deduced) {
334 assert(NTTP->getDepth() == Info.getDeducedDepth() &&
335 "deducing non-type template argument with wrong depth");
337 DeducedTemplateArgument Result = checkDeducedTemplateArguments(
338 S.Context, Deduced[NTTP->getIndex()], NewDeduced);
339 if (Result.isNull()) {
341 Info.FirstArg = Deduced[NTTP->getIndex()];
342 Info.SecondArg = NewDeduced;
343 return Sema::TDK_Inconsistent;
346 Deduced[NTTP->getIndex()] = Result;
347 if (!S.getLangOpts().CPlusPlus17)
348 return Sema::TDK_Success;
350 if (NTTP->isExpandedParameterPack())
351 // FIXME: We may still need to deduce parts of the type here! But we
352 // don't have any way to find which slice of the type to use, and the
353 // type stored on the NTTP itself is nonsense. Perhaps the type of an
354 // expanded NTTP should be a pack expansion type?
355 return Sema::TDK_Success;
357 // Get the type of the parameter for deduction. If it's a (dependent) array
358 // or function type, we will not have decayed it yet, so do that now.
359 QualType ParamType = S.Context.getAdjustedParameterType(NTTP->getType());
360 if (auto *Expansion = dyn_cast<PackExpansionType>(ParamType))
361 ParamType = Expansion->getPattern();
363 // FIXME: It's not clear how deduction of a parameter of reference
364 // type from an argument (of non-reference type) should be performed.
365 // For now, we just remove reference types from both sides and let
366 // the final check for matching types sort out the mess.
367 return DeduceTemplateArgumentsByTypeMatch(
368 S, TemplateParams, ParamType.getNonReferenceType(),
369 ValueType.getNonReferenceType(), Info, Deduced, TDF_SkipNonDependent,
370 /*PartialOrdering=*/false,
371 /*ArrayBound=*/NewDeduced.wasDeducedFromArrayBound());
374 /// \brief Deduce the value of the given non-type template parameter
375 /// from the given integral constant.
376 static Sema::TemplateDeductionResult DeduceNonTypeTemplateArgument(
377 Sema &S, TemplateParameterList *TemplateParams,
378 NonTypeTemplateParmDecl *NTTP, const llvm::APSInt &Value,
379 QualType ValueType, bool DeducedFromArrayBound, TemplateDeductionInfo &Info,
380 SmallVectorImpl<DeducedTemplateArgument> &Deduced) {
381 return DeduceNonTypeTemplateArgument(
382 S, TemplateParams, NTTP,
383 DeducedTemplateArgument(S.Context, Value, ValueType,
384 DeducedFromArrayBound),
385 ValueType, Info, Deduced);
388 /// \brief Deduce the value of the given non-type template parameter
389 /// from the given null pointer template argument type.
390 static Sema::TemplateDeductionResult DeduceNullPtrTemplateArgument(
391 Sema &S, TemplateParameterList *TemplateParams,
392 NonTypeTemplateParmDecl *NTTP, QualType NullPtrType,
393 TemplateDeductionInfo &Info,
394 SmallVectorImpl<DeducedTemplateArgument> &Deduced) {
396 S.ImpCastExprToType(new (S.Context) CXXNullPtrLiteralExpr(
397 S.Context.NullPtrTy, NTTP->getLocation()),
398 NullPtrType, CK_NullToPointer)
400 return DeduceNonTypeTemplateArgument(S, TemplateParams, NTTP,
401 DeducedTemplateArgument(Value),
402 Value->getType(), Info, Deduced);
405 /// \brief Deduce the value of the given non-type template parameter
406 /// from the given type- or value-dependent expression.
408 /// \returns true if deduction succeeded, false otherwise.
409 static Sema::TemplateDeductionResult DeduceNonTypeTemplateArgument(
410 Sema &S, TemplateParameterList *TemplateParams,
411 NonTypeTemplateParmDecl *NTTP, Expr *Value, TemplateDeductionInfo &Info,
412 SmallVectorImpl<DeducedTemplateArgument> &Deduced) {
413 return DeduceNonTypeTemplateArgument(S, TemplateParams, NTTP,
414 DeducedTemplateArgument(Value),
415 Value->getType(), Info, Deduced);
418 /// \brief Deduce the value of the given non-type template parameter
419 /// from the given declaration.
421 /// \returns true if deduction succeeded, false otherwise.
422 static Sema::TemplateDeductionResult DeduceNonTypeTemplateArgument(
423 Sema &S, TemplateParameterList *TemplateParams,
424 NonTypeTemplateParmDecl *NTTP, ValueDecl *D, QualType T,
425 TemplateDeductionInfo &Info,
426 SmallVectorImpl<DeducedTemplateArgument> &Deduced) {
427 D = D ? cast<ValueDecl>(D->getCanonicalDecl()) : nullptr;
428 TemplateArgument New(D, T);
429 return DeduceNonTypeTemplateArgument(
430 S, TemplateParams, NTTP, DeducedTemplateArgument(New), T, Info, Deduced);
433 static Sema::TemplateDeductionResult
434 DeduceTemplateArguments(Sema &S,
435 TemplateParameterList *TemplateParams,
438 TemplateDeductionInfo &Info,
439 SmallVectorImpl<DeducedTemplateArgument> &Deduced) {
440 TemplateDecl *ParamDecl = Param.getAsTemplateDecl();
442 // The parameter type is dependent and is not a template template parameter,
443 // so there is nothing that we can deduce.
444 return Sema::TDK_Success;
447 if (TemplateTemplateParmDecl *TempParam
448 = dyn_cast<TemplateTemplateParmDecl>(ParamDecl)) {
449 // If we're not deducing at this depth, there's nothing to deduce.
450 if (TempParam->getDepth() != Info.getDeducedDepth())
451 return Sema::TDK_Success;
453 DeducedTemplateArgument NewDeduced(S.Context.getCanonicalTemplateName(Arg));
454 DeducedTemplateArgument Result = checkDeducedTemplateArguments(S.Context,
455 Deduced[TempParam->getIndex()],
457 if (Result.isNull()) {
458 Info.Param = TempParam;
459 Info.FirstArg = Deduced[TempParam->getIndex()];
460 Info.SecondArg = NewDeduced;
461 return Sema::TDK_Inconsistent;
464 Deduced[TempParam->getIndex()] = Result;
465 return Sema::TDK_Success;
468 // Verify that the two template names are equivalent.
469 if (S.Context.hasSameTemplateName(Param, Arg))
470 return Sema::TDK_Success;
472 // Mismatch of non-dependent template parameter to argument.
473 Info.FirstArg = TemplateArgument(Param);
474 Info.SecondArg = TemplateArgument(Arg);
475 return Sema::TDK_NonDeducedMismatch;
478 /// \brief Deduce the template arguments by comparing the template parameter
479 /// type (which is a template-id) with the template argument type.
481 /// \param S the Sema
483 /// \param TemplateParams the template parameters that we are deducing
485 /// \param Param the parameter type
487 /// \param Arg the argument type
489 /// \param Info information about the template argument deduction itself
491 /// \param Deduced the deduced template arguments
493 /// \returns the result of template argument deduction so far. Note that a
494 /// "success" result means that template argument deduction has not yet failed,
495 /// but it may still fail, later, for other reasons.
496 static Sema::TemplateDeductionResult
497 DeduceTemplateArguments(Sema &S,
498 TemplateParameterList *TemplateParams,
499 const TemplateSpecializationType *Param,
501 TemplateDeductionInfo &Info,
502 SmallVectorImpl<DeducedTemplateArgument> &Deduced) {
503 assert(Arg.isCanonical() && "Argument type must be canonical");
505 // Treat an injected-class-name as its underlying template-id.
506 if (auto *Injected = dyn_cast<InjectedClassNameType>(Arg))
507 Arg = Injected->getInjectedSpecializationType();
509 // Check whether the template argument is a dependent template-id.
510 if (const TemplateSpecializationType *SpecArg
511 = dyn_cast<TemplateSpecializationType>(Arg)) {
512 // Perform template argument deduction for the template name.
513 if (Sema::TemplateDeductionResult Result
514 = DeduceTemplateArguments(S, TemplateParams,
515 Param->getTemplateName(),
516 SpecArg->getTemplateName(),
521 // Perform template argument deduction on each template
522 // argument. Ignore any missing/extra arguments, since they could be
523 // filled in by default arguments.
524 return DeduceTemplateArguments(S, TemplateParams,
525 Param->template_arguments(),
526 SpecArg->template_arguments(), Info, Deduced,
527 /*NumberOfArgumentsMustMatch=*/false);
530 // If the argument type is a class template specialization, we
531 // perform template argument deduction using its template
533 const RecordType *RecordArg = dyn_cast<RecordType>(Arg);
535 Info.FirstArg = TemplateArgument(QualType(Param, 0));
536 Info.SecondArg = TemplateArgument(Arg);
537 return Sema::TDK_NonDeducedMismatch;
540 ClassTemplateSpecializationDecl *SpecArg
541 = dyn_cast<ClassTemplateSpecializationDecl>(RecordArg->getDecl());
543 Info.FirstArg = TemplateArgument(QualType(Param, 0));
544 Info.SecondArg = TemplateArgument(Arg);
545 return Sema::TDK_NonDeducedMismatch;
548 // Perform template argument deduction for the template name.
549 if (Sema::TemplateDeductionResult Result
550 = DeduceTemplateArguments(S,
552 Param->getTemplateName(),
553 TemplateName(SpecArg->getSpecializedTemplate()),
557 // Perform template argument deduction for the template arguments.
558 return DeduceTemplateArguments(S, TemplateParams, Param->template_arguments(),
559 SpecArg->getTemplateArgs().asArray(), Info,
560 Deduced, /*NumberOfArgumentsMustMatch=*/true);
563 /// \brief Determines whether the given type is an opaque type that
564 /// might be more qualified when instantiated.
565 static bool IsPossiblyOpaquelyQualifiedType(QualType T) {
566 switch (T->getTypeClass()) {
567 case Type::TypeOfExpr:
569 case Type::DependentName:
571 case Type::UnresolvedUsing:
572 case Type::TemplateTypeParm:
575 case Type::ConstantArray:
576 case Type::IncompleteArray:
577 case Type::VariableArray:
578 case Type::DependentSizedArray:
579 return IsPossiblyOpaquelyQualifiedType(
580 cast<ArrayType>(T)->getElementType());
587 /// \brief Retrieve the depth and index of a template parameter.
588 static std::pair<unsigned, unsigned>
589 getDepthAndIndex(NamedDecl *ND) {
590 if (TemplateTypeParmDecl *TTP = dyn_cast<TemplateTypeParmDecl>(ND))
591 return std::make_pair(TTP->getDepth(), TTP->getIndex());
593 if (NonTypeTemplateParmDecl *NTTP = dyn_cast<NonTypeTemplateParmDecl>(ND))
594 return std::make_pair(NTTP->getDepth(), NTTP->getIndex());
596 TemplateTemplateParmDecl *TTP = cast<TemplateTemplateParmDecl>(ND);
597 return std::make_pair(TTP->getDepth(), TTP->getIndex());
600 /// \brief Retrieve the depth and index of an unexpanded parameter pack.
601 static std::pair<unsigned, unsigned>
602 getDepthAndIndex(UnexpandedParameterPack UPP) {
603 if (const TemplateTypeParmType *TTP
604 = UPP.first.dyn_cast<const TemplateTypeParmType *>())
605 return std::make_pair(TTP->getDepth(), TTP->getIndex());
607 return getDepthAndIndex(UPP.first.get<NamedDecl *>());
610 /// \brief Helper function to build a TemplateParameter when we don't
611 /// know its type statically.
612 static TemplateParameter makeTemplateParameter(Decl *D) {
613 if (TemplateTypeParmDecl *TTP = dyn_cast<TemplateTypeParmDecl>(D))
614 return TemplateParameter(TTP);
615 if (NonTypeTemplateParmDecl *NTTP = dyn_cast<NonTypeTemplateParmDecl>(D))
616 return TemplateParameter(NTTP);
618 return TemplateParameter(cast<TemplateTemplateParmDecl>(D));
621 /// A pack that we're currently deducing.
622 struct clang::DeducedPack {
623 DeducedPack(unsigned Index) : Index(Index), Outer(nullptr) {}
625 // The index of the pack.
628 // The old value of the pack before we started deducing it.
629 DeducedTemplateArgument Saved;
631 // A deferred value of this pack from an inner deduction, that couldn't be
632 // deduced because this deduction hadn't happened yet.
633 DeducedTemplateArgument DeferredDeduction;
635 // The new value of the pack.
636 SmallVector<DeducedTemplateArgument, 4> New;
638 // The outer deduction for this pack, if any.
643 /// A scope in which we're performing pack deduction.
644 class PackDeductionScope {
646 PackDeductionScope(Sema &S, TemplateParameterList *TemplateParams,
647 SmallVectorImpl<DeducedTemplateArgument> &Deduced,
648 TemplateDeductionInfo &Info, TemplateArgument Pattern)
649 : S(S), TemplateParams(TemplateParams), Deduced(Deduced), Info(Info) {
650 // Dig out the partially-substituted pack, if there is one.
651 const TemplateArgument *PartialPackArgs = nullptr;
652 unsigned NumPartialPackArgs = 0;
653 std::pair<unsigned, unsigned> PartialPackDepthIndex(-1u, -1u);
654 if (auto *Scope = S.CurrentInstantiationScope)
655 if (auto *Partial = Scope->getPartiallySubstitutedPack(
656 &PartialPackArgs, &NumPartialPackArgs))
657 PartialPackDepthIndex = getDepthAndIndex(Partial);
659 // Compute the set of template parameter indices that correspond to
660 // parameter packs expanded by the pack expansion.
662 llvm::SmallBitVector SawIndices(TemplateParams->size());
664 auto AddPack = [&](unsigned Index) {
665 if (SawIndices[Index])
667 SawIndices[Index] = true;
669 // Save the deduced template argument for the parameter pack expanded
670 // by this pack expansion, then clear out the deduction.
671 DeducedPack Pack(Index);
672 Pack.Saved = Deduced[Index];
673 Deduced[Index] = TemplateArgument();
675 Packs.push_back(Pack);
678 // First look for unexpanded packs in the pattern.
679 SmallVector<UnexpandedParameterPack, 2> Unexpanded;
680 S.collectUnexpandedParameterPacks(Pattern, Unexpanded);
681 for (unsigned I = 0, N = Unexpanded.size(); I != N; ++I) {
682 unsigned Depth, Index;
683 std::tie(Depth, Index) = getDepthAndIndex(Unexpanded[I]);
684 if (Depth == Info.getDeducedDepth())
687 assert(!Packs.empty() && "Pack expansion without unexpanded packs?");
689 // This pack expansion will have been partially expanded iff the only
690 // unexpanded parameter pack within it is the partially-substituted pack.
691 IsPartiallyExpanded =
693 PartialPackDepthIndex ==
694 std::make_pair(Info.getDeducedDepth(), Packs.front().Index);
696 // Skip over the pack elements that were expanded into separate arguments.
697 if (IsPartiallyExpanded)
698 PackElements += NumPartialPackArgs;
700 // We can also have deduced template parameters that do not actually
701 // appear in the pattern, but can be deduced by it (the type of a non-type
702 // template parameter pack, in particular). These won't have prevented us
703 // from partially expanding the pack.
704 llvm::SmallBitVector Used(TemplateParams->size());
705 MarkUsedTemplateParameters(S.Context, Pattern, /*OnlyDeduced*/true,
706 Info.getDeducedDepth(), Used);
707 for (int Index = Used.find_first(); Index != -1;
708 Index = Used.find_next(Index))
709 if (TemplateParams->getParam(Index)->isParameterPack())
713 for (auto &Pack : Packs) {
714 if (Info.PendingDeducedPacks.size() > Pack.Index)
715 Pack.Outer = Info.PendingDeducedPacks[Pack.Index];
717 Info.PendingDeducedPacks.resize(Pack.Index + 1);
718 Info.PendingDeducedPacks[Pack.Index] = &Pack;
720 if (PartialPackDepthIndex ==
721 std::make_pair(Info.getDeducedDepth(), Pack.Index)) {
722 Pack.New.append(PartialPackArgs, PartialPackArgs + NumPartialPackArgs);
723 // We pre-populate the deduced value of the partially-substituted
724 // pack with the specified value. This is not entirely correct: the
725 // value is supposed to have been substituted, not deduced, but the
726 // cases where this is observable require an exact type match anyway.
728 // FIXME: If we could represent a "depth i, index j, pack elem k"
729 // parameter, we could substitute the partially-substituted pack
730 // everywhere and avoid this.
731 if (Pack.New.size() > PackElements)
732 Deduced[Pack.Index] = Pack.New[PackElements];
737 ~PackDeductionScope() {
738 for (auto &Pack : Packs)
739 Info.PendingDeducedPacks[Pack.Index] = Pack.Outer;
742 /// Determine whether this pack has already been partially expanded into a
743 /// sequence of (prior) function parameters / template arguments.
744 bool isPartiallyExpanded() { return IsPartiallyExpanded; }
746 /// Move to deducing the next element in each pack that is being deduced.
747 void nextPackElement() {
748 // Capture the deduced template arguments for each parameter pack expanded
749 // by this pack expansion, add them to the list of arguments we've deduced
750 // for that pack, then clear out the deduced argument.
751 for (auto &Pack : Packs) {
752 DeducedTemplateArgument &DeducedArg = Deduced[Pack.Index];
753 if (!Pack.New.empty() || !DeducedArg.isNull()) {
754 while (Pack.New.size() < PackElements)
755 Pack.New.push_back(DeducedTemplateArgument());
756 if (Pack.New.size() == PackElements)
757 Pack.New.push_back(DeducedArg);
759 Pack.New[PackElements] = DeducedArg;
760 DeducedArg = Pack.New.size() > PackElements + 1
761 ? Pack.New[PackElements + 1]
762 : DeducedTemplateArgument();
768 /// \brief Finish template argument deduction for a set of argument packs,
769 /// producing the argument packs and checking for consistency with prior
771 Sema::TemplateDeductionResult finish() {
772 // Build argument packs for each of the parameter packs expanded by this
774 for (auto &Pack : Packs) {
775 // Put back the old value for this pack.
776 Deduced[Pack.Index] = Pack.Saved;
778 // Build or find a new value for this pack.
779 DeducedTemplateArgument NewPack;
780 if (PackElements && Pack.New.empty()) {
781 if (Pack.DeferredDeduction.isNull()) {
782 // We were not able to deduce anything for this parameter pack
783 // (because it only appeared in non-deduced contexts), so just
784 // restore the saved argument pack.
788 NewPack = Pack.DeferredDeduction;
789 Pack.DeferredDeduction = TemplateArgument();
790 } else if (Pack.New.empty()) {
791 // If we deduced an empty argument pack, create it now.
792 NewPack = DeducedTemplateArgument(TemplateArgument::getEmptyPack());
794 TemplateArgument *ArgumentPack =
795 new (S.Context) TemplateArgument[Pack.New.size()];
796 std::copy(Pack.New.begin(), Pack.New.end(), ArgumentPack);
797 NewPack = DeducedTemplateArgument(
798 TemplateArgument(llvm::makeArrayRef(ArgumentPack, Pack.New.size())),
799 // FIXME: This is wrong, it's possible that some pack elements are
800 // deduced from an array bound and others are not:
801 // template<typename ...T, T ...V> void g(const T (&...p)[V]);
802 // g({1, 2, 3}, {{}, {}});
803 // ... should deduce T = {int, size_t (from array bound)}.
804 Pack.New[0].wasDeducedFromArrayBound());
807 // Pick where we're going to put the merged pack.
808 DeducedTemplateArgument *Loc;
810 if (Pack.Outer->DeferredDeduction.isNull()) {
811 // Defer checking this pack until we have a complete pack to compare
813 Pack.Outer->DeferredDeduction = NewPack;
816 Loc = &Pack.Outer->DeferredDeduction;
818 Loc = &Deduced[Pack.Index];
821 // Check the new pack matches any previous value.
822 DeducedTemplateArgument OldPack = *Loc;
823 DeducedTemplateArgument Result =
824 checkDeducedTemplateArguments(S.Context, OldPack, NewPack);
826 // If we deferred a deduction of this pack, check that one now too.
827 if (!Result.isNull() && !Pack.DeferredDeduction.isNull()) {
829 NewPack = Pack.DeferredDeduction;
830 Result = checkDeducedTemplateArguments(S.Context, OldPack, NewPack);
833 if (Result.isNull()) {
835 makeTemplateParameter(TemplateParams->getParam(Pack.Index));
836 Info.FirstArg = OldPack;
837 Info.SecondArg = NewPack;
838 return Sema::TDK_Inconsistent;
844 return Sema::TDK_Success;
849 TemplateParameterList *TemplateParams;
850 SmallVectorImpl<DeducedTemplateArgument> &Deduced;
851 TemplateDeductionInfo &Info;
852 unsigned PackElements = 0;
853 bool IsPartiallyExpanded = false;
855 SmallVector<DeducedPack, 2> Packs;
859 /// \brief Deduce the template arguments by comparing the list of parameter
860 /// types to the list of argument types, as in the parameter-type-lists of
861 /// function types (C++ [temp.deduct.type]p10).
863 /// \param S The semantic analysis object within which we are deducing
865 /// \param TemplateParams The template parameters that we are deducing
867 /// \param Params The list of parameter types
869 /// \param NumParams The number of types in \c Params
871 /// \param Args The list of argument types
873 /// \param NumArgs The number of types in \c Args
875 /// \param Info information about the template argument deduction itself
877 /// \param Deduced the deduced template arguments
879 /// \param TDF bitwise OR of the TemplateDeductionFlags bits that describe
880 /// how template argument deduction is performed.
882 /// \param PartialOrdering If true, we are performing template argument
883 /// deduction for during partial ordering for a call
884 /// (C++0x [temp.deduct.partial]).
886 /// \returns the result of template argument deduction so far. Note that a
887 /// "success" result means that template argument deduction has not yet failed,
888 /// but it may still fail, later, for other reasons.
889 static Sema::TemplateDeductionResult
890 DeduceTemplateArguments(Sema &S,
891 TemplateParameterList *TemplateParams,
892 const QualType *Params, unsigned NumParams,
893 const QualType *Args, unsigned NumArgs,
894 TemplateDeductionInfo &Info,
895 SmallVectorImpl<DeducedTemplateArgument> &Deduced,
897 bool PartialOrdering = false) {
898 // Fast-path check to see if we have too many/too few arguments.
899 if (NumParams != NumArgs &&
900 !(NumParams && isa<PackExpansionType>(Params[NumParams - 1])) &&
901 !(NumArgs && isa<PackExpansionType>(Args[NumArgs - 1])))
902 return Sema::TDK_MiscellaneousDeductionFailure;
904 // C++0x [temp.deduct.type]p10:
905 // Similarly, if P has a form that contains (T), then each parameter type
906 // Pi of the respective parameter-type- list of P is compared with the
907 // corresponding parameter type Ai of the corresponding parameter-type-list
909 unsigned ArgIdx = 0, ParamIdx = 0;
910 for (; ParamIdx != NumParams; ++ParamIdx) {
911 // Check argument types.
912 const PackExpansionType *Expansion
913 = dyn_cast<PackExpansionType>(Params[ParamIdx]);
915 // Simple case: compare the parameter and argument types at this point.
917 // Make sure we have an argument.
918 if (ArgIdx >= NumArgs)
919 return Sema::TDK_MiscellaneousDeductionFailure;
921 if (isa<PackExpansionType>(Args[ArgIdx])) {
922 // C++0x [temp.deduct.type]p22:
923 // If the original function parameter associated with A is a function
924 // parameter pack and the function parameter associated with P is not
925 // a function parameter pack, then template argument deduction fails.
926 return Sema::TDK_MiscellaneousDeductionFailure;
929 if (Sema::TemplateDeductionResult Result
930 = DeduceTemplateArgumentsByTypeMatch(S, TemplateParams,
931 Params[ParamIdx], Args[ArgIdx],
940 // C++0x [temp.deduct.type]p5:
941 // The non-deduced contexts are:
942 // - A function parameter pack that does not occur at the end of the
943 // parameter-declaration-clause.
944 if (ParamIdx + 1 < NumParams)
945 return Sema::TDK_Success;
947 // C++0x [temp.deduct.type]p10:
948 // If the parameter-declaration corresponding to Pi is a function
949 // parameter pack, then the type of its declarator- id is compared with
950 // each remaining parameter type in the parameter-type-list of A. Each
951 // comparison deduces template arguments for subsequent positions in the
952 // template parameter packs expanded by the function parameter pack.
954 QualType Pattern = Expansion->getPattern();
955 PackDeductionScope PackScope(S, TemplateParams, Deduced, Info, Pattern);
957 for (; ArgIdx < NumArgs; ++ArgIdx) {
958 // Deduce template arguments from the pattern.
959 if (Sema::TemplateDeductionResult Result
960 = DeduceTemplateArgumentsByTypeMatch(S, TemplateParams, Pattern,
961 Args[ArgIdx], Info, Deduced,
962 TDF, PartialOrdering))
965 PackScope.nextPackElement();
968 // Build argument packs for each of the parameter packs expanded by this
970 if (auto Result = PackScope.finish())
974 // Make sure we don't have any extra arguments.
975 if (ArgIdx < NumArgs)
976 return Sema::TDK_MiscellaneousDeductionFailure;
978 return Sema::TDK_Success;
981 /// \brief Determine whether the parameter has qualifiers that are either
982 /// inconsistent with or a superset of the argument's qualifiers.
983 static bool hasInconsistentOrSupersetQualifiersOf(QualType ParamType,
985 Qualifiers ParamQs = ParamType.getQualifiers();
986 Qualifiers ArgQs = ArgType.getQualifiers();
988 if (ParamQs == ArgQs)
991 // Mismatched (but not missing) Objective-C GC attributes.
992 if (ParamQs.getObjCGCAttr() != ArgQs.getObjCGCAttr() &&
993 ParamQs.hasObjCGCAttr())
996 // Mismatched (but not missing) address spaces.
997 if (ParamQs.getAddressSpace() != ArgQs.getAddressSpace() &&
998 ParamQs.hasAddressSpace())
1001 // Mismatched (but not missing) Objective-C lifetime qualifiers.
1002 if (ParamQs.getObjCLifetime() != ArgQs.getObjCLifetime() &&
1003 ParamQs.hasObjCLifetime())
1006 // CVR qualifier superset.
1007 return (ParamQs.getCVRQualifiers() != ArgQs.getCVRQualifiers()) &&
1008 ((ParamQs.getCVRQualifiers() | ArgQs.getCVRQualifiers())
1009 == ParamQs.getCVRQualifiers());
1012 /// \brief Compare types for equality with respect to possibly compatible
1013 /// function types (noreturn adjustment, implicit calling conventions). If any
1014 /// of parameter and argument is not a function, just perform type comparison.
1016 /// \param Param the template parameter type.
1018 /// \param Arg the argument type.
1019 bool Sema::isSameOrCompatibleFunctionType(CanQualType Param,
1021 const FunctionType *ParamFunction = Param->getAs<FunctionType>(),
1022 *ArgFunction = Arg->getAs<FunctionType>();
1024 // Just compare if not functions.
1025 if (!ParamFunction || !ArgFunction)
1026 return Param == Arg;
1028 // Noreturn and noexcept adjustment.
1029 QualType AdjustedParam;
1030 if (IsFunctionConversion(Param, Arg, AdjustedParam))
1031 return Arg == Context.getCanonicalType(AdjustedParam);
1033 // FIXME: Compatible calling conventions.
1035 return Param == Arg;
1038 /// Get the index of the first template parameter that was originally from the
1039 /// innermost template-parameter-list. This is 0 except when we concatenate
1040 /// the template parameter lists of a class template and a constructor template
1041 /// when forming an implicit deduction guide.
1042 static unsigned getFirstInnerIndex(FunctionTemplateDecl *FTD) {
1043 auto *Guide = dyn_cast<CXXDeductionGuideDecl>(FTD->getTemplatedDecl());
1044 if (!Guide || !Guide->isImplicit())
1046 return Guide->getDeducedTemplate()->getTemplateParameters()->size();
1049 /// Determine whether a type denotes a forwarding reference.
1050 static bool isForwardingReference(QualType Param, unsigned FirstInnerIndex) {
1051 // C++1z [temp.deduct.call]p3:
1052 // A forwarding reference is an rvalue reference to a cv-unqualified
1053 // template parameter that does not represent a template parameter of a
1055 if (auto *ParamRef = Param->getAs<RValueReferenceType>()) {
1056 if (ParamRef->getPointeeType().getQualifiers())
1058 auto *TypeParm = ParamRef->getPointeeType()->getAs<TemplateTypeParmType>();
1059 return TypeParm && TypeParm->getIndex() >= FirstInnerIndex;
1064 /// \brief Deduce the template arguments by comparing the parameter type and
1065 /// the argument type (C++ [temp.deduct.type]).
1067 /// \param S the semantic analysis object within which we are deducing
1069 /// \param TemplateParams the template parameters that we are deducing
1071 /// \param ParamIn the parameter type
1073 /// \param ArgIn the argument type
1075 /// \param Info information about the template argument deduction itself
1077 /// \param Deduced the deduced template arguments
1079 /// \param TDF bitwise OR of the TemplateDeductionFlags bits that describe
1080 /// how template argument deduction is performed.
1082 /// \param PartialOrdering Whether we're performing template argument deduction
1083 /// in the context of partial ordering (C++0x [temp.deduct.partial]).
1085 /// \returns the result of template argument deduction so far. Note that a
1086 /// "success" result means that template argument deduction has not yet failed,
1087 /// but it may still fail, later, for other reasons.
1088 static Sema::TemplateDeductionResult
1089 DeduceTemplateArgumentsByTypeMatch(Sema &S,
1090 TemplateParameterList *TemplateParams,
1091 QualType ParamIn, QualType ArgIn,
1092 TemplateDeductionInfo &Info,
1093 SmallVectorImpl<DeducedTemplateArgument> &Deduced,
1095 bool PartialOrdering,
1096 bool DeducedFromArrayBound) {
1097 // We only want to look at the canonical types, since typedefs and
1098 // sugar are not part of template argument deduction.
1099 QualType Param = S.Context.getCanonicalType(ParamIn);
1100 QualType Arg = S.Context.getCanonicalType(ArgIn);
1102 // If the argument type is a pack expansion, look at its pattern.
1103 // This isn't explicitly called out
1104 if (const PackExpansionType *ArgExpansion
1105 = dyn_cast<PackExpansionType>(Arg))
1106 Arg = ArgExpansion->getPattern();
1108 if (PartialOrdering) {
1109 // C++11 [temp.deduct.partial]p5:
1110 // Before the partial ordering is done, certain transformations are
1111 // performed on the types used for partial ordering:
1112 // - If P is a reference type, P is replaced by the type referred to.
1113 const ReferenceType *ParamRef = Param->getAs<ReferenceType>();
1115 Param = ParamRef->getPointeeType();
1117 // - If A is a reference type, A is replaced by the type referred to.
1118 const ReferenceType *ArgRef = Arg->getAs<ReferenceType>();
1120 Arg = ArgRef->getPointeeType();
1122 if (ParamRef && ArgRef && S.Context.hasSameUnqualifiedType(Param, Arg)) {
1123 // C++11 [temp.deduct.partial]p9:
1124 // If, for a given type, deduction succeeds in both directions (i.e.,
1125 // the types are identical after the transformations above) and both
1126 // P and A were reference types [...]:
1127 // - if [one type] was an lvalue reference and [the other type] was
1128 // not, [the other type] is not considered to be at least as
1129 // specialized as [the first type]
1130 // - if [one type] is more cv-qualified than [the other type],
1131 // [the other type] is not considered to be at least as specialized
1132 // as [the first type]
1133 // Objective-C ARC adds:
1134 // - [one type] has non-trivial lifetime, [the other type] has
1135 // __unsafe_unretained lifetime, and the types are otherwise
1138 // A is "considered to be at least as specialized" as P iff deduction
1139 // succeeds, so we model this as a deduction failure. Note that
1140 // [the first type] is P and [the other type] is A here; the standard
1141 // gets this backwards.
1142 Qualifiers ParamQuals = Param.getQualifiers();
1143 Qualifiers ArgQuals = Arg.getQualifiers();
1144 if ((ParamRef->isLValueReferenceType() &&
1145 !ArgRef->isLValueReferenceType()) ||
1146 ParamQuals.isStrictSupersetOf(ArgQuals) ||
1147 (ParamQuals.hasNonTrivialObjCLifetime() &&
1148 ArgQuals.getObjCLifetime() == Qualifiers::OCL_ExplicitNone &&
1149 ParamQuals.withoutObjCLifetime() ==
1150 ArgQuals.withoutObjCLifetime())) {
1151 Info.FirstArg = TemplateArgument(ParamIn);
1152 Info.SecondArg = TemplateArgument(ArgIn);
1153 return Sema::TDK_NonDeducedMismatch;
1157 // C++11 [temp.deduct.partial]p7:
1158 // Remove any top-level cv-qualifiers:
1159 // - If P is a cv-qualified type, P is replaced by the cv-unqualified
1161 Param = Param.getUnqualifiedType();
1162 // - If A is a cv-qualified type, A is replaced by the cv-unqualified
1164 Arg = Arg.getUnqualifiedType();
1166 // C++0x [temp.deduct.call]p4 bullet 1:
1167 // - If the original P is a reference type, the deduced A (i.e., the type
1168 // referred to by the reference) can be more cv-qualified than the
1170 if (TDF & TDF_ParamWithReferenceType) {
1172 QualType UnqualParam = S.Context.getUnqualifiedArrayType(Param, Quals);
1173 Quals.setCVRQualifiers(Quals.getCVRQualifiers() &
1174 Arg.getCVRQualifiers());
1175 Param = S.Context.getQualifiedType(UnqualParam, Quals);
1178 if ((TDF & TDF_TopLevelParameterTypeList) && !Param->isFunctionType()) {
1179 // C++0x [temp.deduct.type]p10:
1180 // If P and A are function types that originated from deduction when
1181 // taking the address of a function template (14.8.2.2) or when deducing
1182 // template arguments from a function declaration (14.8.2.6) and Pi and
1183 // Ai are parameters of the top-level parameter-type-list of P and A,
1184 // respectively, Pi is adjusted if it is a forwarding reference and Ai
1185 // is an lvalue reference, in
1186 // which case the type of Pi is changed to be the template parameter
1187 // type (i.e., T&& is changed to simply T). [ Note: As a result, when
1188 // Pi is T&& and Ai is X&, the adjusted Pi will be T, causing T to be
1189 // deduced as X&. - end note ]
1190 TDF &= ~TDF_TopLevelParameterTypeList;
1191 if (isForwardingReference(Param, 0) && Arg->isLValueReferenceType())
1192 Param = Param->getPointeeType();
1196 // C++ [temp.deduct.type]p9:
1197 // A template type argument T, a template template argument TT or a
1198 // template non-type argument i can be deduced if P and A have one of
1199 // the following forms:
1203 if (const TemplateTypeParmType *TemplateTypeParm
1204 = Param->getAs<TemplateTypeParmType>()) {
1205 // Just skip any attempts to deduce from a placeholder type or a parameter
1206 // at a different depth.
1207 if (Arg->isPlaceholderType() ||
1208 Info.getDeducedDepth() != TemplateTypeParm->getDepth())
1209 return Sema::TDK_Success;
1211 unsigned Index = TemplateTypeParm->getIndex();
1212 bool RecanonicalizeArg = false;
1214 // If the argument type is an array type, move the qualifiers up to the
1215 // top level, so they can be matched with the qualifiers on the parameter.
1216 if (isa<ArrayType>(Arg)) {
1218 Arg = S.Context.getUnqualifiedArrayType(Arg, Quals);
1220 Arg = S.Context.getQualifiedType(Arg, Quals);
1221 RecanonicalizeArg = true;
1225 // The argument type can not be less qualified than the parameter
1227 if (!(TDF & TDF_IgnoreQualifiers) &&
1228 hasInconsistentOrSupersetQualifiersOf(Param, Arg)) {
1229 Info.Param = cast<TemplateTypeParmDecl>(TemplateParams->getParam(Index));
1230 Info.FirstArg = TemplateArgument(Param);
1231 Info.SecondArg = TemplateArgument(Arg);
1232 return Sema::TDK_Underqualified;
1235 assert(TemplateTypeParm->getDepth() == Info.getDeducedDepth() &&
1236 "saw template type parameter with wrong depth");
1237 assert(Arg != S.Context.OverloadTy && "Unresolved overloaded function");
1238 QualType DeducedType = Arg;
1240 // Remove any qualifiers on the parameter from the deduced type.
1241 // We checked the qualifiers for consistency above.
1242 Qualifiers DeducedQs = DeducedType.getQualifiers();
1243 Qualifiers ParamQs = Param.getQualifiers();
1244 DeducedQs.removeCVRQualifiers(ParamQs.getCVRQualifiers());
1245 if (ParamQs.hasObjCGCAttr())
1246 DeducedQs.removeObjCGCAttr();
1247 if (ParamQs.hasAddressSpace())
1248 DeducedQs.removeAddressSpace();
1249 if (ParamQs.hasObjCLifetime())
1250 DeducedQs.removeObjCLifetime();
1253 // If template deduction would produce a lifetime qualifier on a type
1254 // that is not a lifetime type, template argument deduction fails.
1255 if (ParamQs.hasObjCLifetime() && !DeducedType->isObjCLifetimeType() &&
1256 !DeducedType->isDependentType()) {
1257 Info.Param = cast<TemplateTypeParmDecl>(TemplateParams->getParam(Index));
1258 Info.FirstArg = TemplateArgument(Param);
1259 Info.SecondArg = TemplateArgument(Arg);
1260 return Sema::TDK_Underqualified;
1264 // If template deduction would produce an argument type with lifetime type
1265 // but no lifetime qualifier, the __strong lifetime qualifier is inferred.
1266 if (S.getLangOpts().ObjCAutoRefCount &&
1267 DeducedType->isObjCLifetimeType() &&
1268 !DeducedQs.hasObjCLifetime())
1269 DeducedQs.setObjCLifetime(Qualifiers::OCL_Strong);
1271 DeducedType = S.Context.getQualifiedType(DeducedType.getUnqualifiedType(),
1274 if (RecanonicalizeArg)
1275 DeducedType = S.Context.getCanonicalType(DeducedType);
1277 DeducedTemplateArgument NewDeduced(DeducedType, DeducedFromArrayBound);
1278 DeducedTemplateArgument Result = checkDeducedTemplateArguments(S.Context,
1281 if (Result.isNull()) {
1282 Info.Param = cast<TemplateTypeParmDecl>(TemplateParams->getParam(Index));
1283 Info.FirstArg = Deduced[Index];
1284 Info.SecondArg = NewDeduced;
1285 return Sema::TDK_Inconsistent;
1288 Deduced[Index] = Result;
1289 return Sema::TDK_Success;
1292 // Set up the template argument deduction information for a failure.
1293 Info.FirstArg = TemplateArgument(ParamIn);
1294 Info.SecondArg = TemplateArgument(ArgIn);
1296 // If the parameter is an already-substituted template parameter
1297 // pack, do nothing: we don't know which of its arguments to look
1298 // at, so we have to wait until all of the parameter packs in this
1299 // expansion have arguments.
1300 if (isa<SubstTemplateTypeParmPackType>(Param))
1301 return Sema::TDK_Success;
1303 // Check the cv-qualifiers on the parameter and argument types.
1304 CanQualType CanParam = S.Context.getCanonicalType(Param);
1305 CanQualType CanArg = S.Context.getCanonicalType(Arg);
1306 if (!(TDF & TDF_IgnoreQualifiers)) {
1307 if (TDF & TDF_ParamWithReferenceType) {
1308 if (hasInconsistentOrSupersetQualifiersOf(Param, Arg))
1309 return Sema::TDK_NonDeducedMismatch;
1310 } else if (!IsPossiblyOpaquelyQualifiedType(Param)) {
1311 if (Param.getCVRQualifiers() != Arg.getCVRQualifiers())
1312 return Sema::TDK_NonDeducedMismatch;
1315 // If the parameter type is not dependent, there is nothing to deduce.
1316 if (!Param->isDependentType()) {
1317 if (!(TDF & TDF_SkipNonDependent)) {
1319 (TDF & TDF_AllowCompatibleFunctionType)
1320 ? !S.isSameOrCompatibleFunctionType(CanParam, CanArg)
1323 return Sema::TDK_NonDeducedMismatch;
1326 return Sema::TDK_Success;
1328 } else if (!Param->isDependentType()) {
1329 CanQualType ParamUnqualType = CanParam.getUnqualifiedType(),
1330 ArgUnqualType = CanArg.getUnqualifiedType();
1332 (TDF & TDF_AllowCompatibleFunctionType)
1333 ? S.isSameOrCompatibleFunctionType(ParamUnqualType, ArgUnqualType)
1334 : ParamUnqualType == ArgUnqualType;
1336 return Sema::TDK_Success;
1339 switch (Param->getTypeClass()) {
1340 // Non-canonical types cannot appear here.
1341 #define NON_CANONICAL_TYPE(Class, Base) \
1342 case Type::Class: llvm_unreachable("deducing non-canonical type: " #Class);
1343 #define TYPE(Class, Base)
1344 #include "clang/AST/TypeNodes.def"
1346 case Type::TemplateTypeParm:
1347 case Type::SubstTemplateTypeParmPack:
1348 llvm_unreachable("Type nodes handled above");
1350 // These types cannot be dependent, so simply check whether the types are
1353 case Type::VariableArray:
1355 case Type::FunctionNoProto:
1358 case Type::ObjCObject:
1359 case Type::ObjCInterface:
1360 case Type::ObjCObjectPointer: {
1361 if (TDF & TDF_SkipNonDependent)
1362 return Sema::TDK_Success;
1364 if (TDF & TDF_IgnoreQualifiers) {
1365 Param = Param.getUnqualifiedType();
1366 Arg = Arg.getUnqualifiedType();
1369 return Param == Arg? Sema::TDK_Success : Sema::TDK_NonDeducedMismatch;
1372 // _Complex T [placeholder extension]
1374 if (const ComplexType *ComplexArg = Arg->getAs<ComplexType>())
1375 return DeduceTemplateArgumentsByTypeMatch(S, TemplateParams,
1376 cast<ComplexType>(Param)->getElementType(),
1377 ComplexArg->getElementType(),
1378 Info, Deduced, TDF);
1380 return Sema::TDK_NonDeducedMismatch;
1382 // _Atomic T [extension]
1384 if (const AtomicType *AtomicArg = Arg->getAs<AtomicType>())
1385 return DeduceTemplateArgumentsByTypeMatch(S, TemplateParams,
1386 cast<AtomicType>(Param)->getValueType(),
1387 AtomicArg->getValueType(),
1388 Info, Deduced, TDF);
1390 return Sema::TDK_NonDeducedMismatch;
1393 case Type::Pointer: {
1394 QualType PointeeType;
1395 if (const PointerType *PointerArg = Arg->getAs<PointerType>()) {
1396 PointeeType = PointerArg->getPointeeType();
1397 } else if (const ObjCObjectPointerType *PointerArg
1398 = Arg->getAs<ObjCObjectPointerType>()) {
1399 PointeeType = PointerArg->getPointeeType();
1401 return Sema::TDK_NonDeducedMismatch;
1404 unsigned SubTDF = TDF & (TDF_IgnoreQualifiers | TDF_DerivedClass);
1405 return DeduceTemplateArgumentsByTypeMatch(S, TemplateParams,
1406 cast<PointerType>(Param)->getPointeeType(),
1408 Info, Deduced, SubTDF);
1412 case Type::LValueReference: {
1413 const LValueReferenceType *ReferenceArg =
1414 Arg->getAs<LValueReferenceType>();
1416 return Sema::TDK_NonDeducedMismatch;
1418 return DeduceTemplateArgumentsByTypeMatch(S, TemplateParams,
1419 cast<LValueReferenceType>(Param)->getPointeeType(),
1420 ReferenceArg->getPointeeType(), Info, Deduced, 0);
1424 case Type::RValueReference: {
1425 const RValueReferenceType *ReferenceArg =
1426 Arg->getAs<RValueReferenceType>();
1428 return Sema::TDK_NonDeducedMismatch;
1430 return DeduceTemplateArgumentsByTypeMatch(S, TemplateParams,
1431 cast<RValueReferenceType>(Param)->getPointeeType(),
1432 ReferenceArg->getPointeeType(),
1436 // T [] (implied, but not stated explicitly)
1437 case Type::IncompleteArray: {
1438 const IncompleteArrayType *IncompleteArrayArg =
1439 S.Context.getAsIncompleteArrayType(Arg);
1440 if (!IncompleteArrayArg)
1441 return Sema::TDK_NonDeducedMismatch;
1443 unsigned SubTDF = TDF & TDF_IgnoreQualifiers;
1444 return DeduceTemplateArgumentsByTypeMatch(S, TemplateParams,
1445 S.Context.getAsIncompleteArrayType(Param)->getElementType(),
1446 IncompleteArrayArg->getElementType(),
1447 Info, Deduced, SubTDF);
1450 // T [integer-constant]
1451 case Type::ConstantArray: {
1452 const ConstantArrayType *ConstantArrayArg =
1453 S.Context.getAsConstantArrayType(Arg);
1454 if (!ConstantArrayArg)
1455 return Sema::TDK_NonDeducedMismatch;
1457 const ConstantArrayType *ConstantArrayParm =
1458 S.Context.getAsConstantArrayType(Param);
1459 if (ConstantArrayArg->getSize() != ConstantArrayParm->getSize())
1460 return Sema::TDK_NonDeducedMismatch;
1462 unsigned SubTDF = TDF & TDF_IgnoreQualifiers;
1463 return DeduceTemplateArgumentsByTypeMatch(S, TemplateParams,
1464 ConstantArrayParm->getElementType(),
1465 ConstantArrayArg->getElementType(),
1466 Info, Deduced, SubTDF);
1470 case Type::DependentSizedArray: {
1471 const ArrayType *ArrayArg = S.Context.getAsArrayType(Arg);
1473 return Sema::TDK_NonDeducedMismatch;
1475 unsigned SubTDF = TDF & TDF_IgnoreQualifiers;
1477 // Check the element type of the arrays
1478 const DependentSizedArrayType *DependentArrayParm
1479 = S.Context.getAsDependentSizedArrayType(Param);
1480 if (Sema::TemplateDeductionResult Result
1481 = DeduceTemplateArgumentsByTypeMatch(S, TemplateParams,
1482 DependentArrayParm->getElementType(),
1483 ArrayArg->getElementType(),
1484 Info, Deduced, SubTDF))
1487 // Determine the array bound is something we can deduce.
1488 NonTypeTemplateParmDecl *NTTP
1489 = getDeducedParameterFromExpr(Info, DependentArrayParm->getSizeExpr());
1491 return Sema::TDK_Success;
1493 // We can perform template argument deduction for the given non-type
1494 // template parameter.
1495 assert(NTTP->getDepth() == Info.getDeducedDepth() &&
1496 "saw non-type template parameter with wrong depth");
1497 if (const ConstantArrayType *ConstantArrayArg
1498 = dyn_cast<ConstantArrayType>(ArrayArg)) {
1499 llvm::APSInt Size(ConstantArrayArg->getSize());
1500 return DeduceNonTypeTemplateArgument(S, TemplateParams, NTTP, Size,
1501 S.Context.getSizeType(),
1502 /*ArrayBound=*/true,
1505 if (const DependentSizedArrayType *DependentArrayArg
1506 = dyn_cast<DependentSizedArrayType>(ArrayArg))
1507 if (DependentArrayArg->getSizeExpr())
1508 return DeduceNonTypeTemplateArgument(S, TemplateParams, NTTP,
1509 DependentArrayArg->getSizeExpr(),
1512 // Incomplete type does not match a dependently-sized array type
1513 return Sema::TDK_NonDeducedMismatch;
1519 case Type::FunctionProto: {
1520 unsigned SubTDF = TDF & TDF_TopLevelParameterTypeList;
1521 const FunctionProtoType *FunctionProtoArg =
1522 dyn_cast<FunctionProtoType>(Arg);
1523 if (!FunctionProtoArg)
1524 return Sema::TDK_NonDeducedMismatch;
1526 const FunctionProtoType *FunctionProtoParam =
1527 cast<FunctionProtoType>(Param);
1529 if (FunctionProtoParam->getTypeQuals()
1530 != FunctionProtoArg->getTypeQuals() ||
1531 FunctionProtoParam->getRefQualifier()
1532 != FunctionProtoArg->getRefQualifier() ||
1533 FunctionProtoParam->isVariadic() != FunctionProtoArg->isVariadic())
1534 return Sema::TDK_NonDeducedMismatch;
1536 // Check return types.
1537 if (auto Result = DeduceTemplateArgumentsByTypeMatch(
1538 S, TemplateParams, FunctionProtoParam->getReturnType(),
1539 FunctionProtoArg->getReturnType(), Info, Deduced, 0))
1542 // Check parameter types.
1543 if (auto Result = DeduceTemplateArguments(
1544 S, TemplateParams, FunctionProtoParam->param_type_begin(),
1545 FunctionProtoParam->getNumParams(),
1546 FunctionProtoArg->param_type_begin(),
1547 FunctionProtoArg->getNumParams(), Info, Deduced, SubTDF))
1550 if (TDF & TDF_AllowCompatibleFunctionType)
1551 return Sema::TDK_Success;
1553 // FIXME: Per core-2016/10/1019 (no corresponding core issue yet), permit
1554 // deducing through the noexcept-specifier if it's part of the canonical
1555 // type. libstdc++ relies on this.
1556 Expr *NoexceptExpr = FunctionProtoParam->getNoexceptExpr();
1557 if (NonTypeTemplateParmDecl *NTTP =
1558 NoexceptExpr ? getDeducedParameterFromExpr(Info, NoexceptExpr)
1560 assert(NTTP->getDepth() == Info.getDeducedDepth() &&
1561 "saw non-type template parameter with wrong depth");
1563 llvm::APSInt Noexcept(1);
1564 switch (FunctionProtoArg->canThrow(S.Context)) {
1570 // We give E in noexcept(E) the "deduced from array bound" treatment.
1571 // FIXME: Should we?
1572 return DeduceNonTypeTemplateArgument(
1573 S, TemplateParams, NTTP, Noexcept, S.Context.BoolTy,
1574 /*ArrayBound*/true, Info, Deduced);
1577 if (Expr *ArgNoexceptExpr = FunctionProtoArg->getNoexceptExpr())
1578 return DeduceNonTypeTemplateArgument(
1579 S, TemplateParams, NTTP, ArgNoexceptExpr, Info, Deduced);
1580 // Can't deduce anything from throw(T...).
1584 // FIXME: Detect non-deduced exception specification mismatches?
1586 return Sema::TDK_Success;
1589 case Type::InjectedClassName: {
1590 // Treat a template's injected-class-name as if the template
1591 // specialization type had been used.
1592 Param = cast<InjectedClassNameType>(Param)
1593 ->getInjectedSpecializationType();
1594 assert(isa<TemplateSpecializationType>(Param) &&
1595 "injected class name is not a template specialization type");
1599 // template-name<T> (where template-name refers to a class template)
1604 case Type::TemplateSpecialization: {
1605 const TemplateSpecializationType *SpecParam =
1606 cast<TemplateSpecializationType>(Param);
1608 // When Arg cannot be a derived class, we can just try to deduce template
1609 // arguments from the template-id.
1610 const RecordType *RecordT = Arg->getAs<RecordType>();
1611 if (!(TDF & TDF_DerivedClass) || !RecordT)
1612 return DeduceTemplateArguments(S, TemplateParams, SpecParam, Arg, Info,
1615 SmallVector<DeducedTemplateArgument, 8> DeducedOrig(Deduced.begin(),
1618 Sema::TemplateDeductionResult Result = DeduceTemplateArguments(
1619 S, TemplateParams, SpecParam, Arg, Info, Deduced);
1621 if (Result == Sema::TDK_Success)
1624 // We cannot inspect base classes as part of deduction when the type
1625 // is incomplete, so either instantiate any templates necessary to
1626 // complete the type, or skip over it if it cannot be completed.
1627 if (!S.isCompleteType(Info.getLocation(), Arg))
1630 // C++14 [temp.deduct.call] p4b3:
1631 // If P is a class and P has the form simple-template-id, then the
1632 // transformed A can be a derived class of the deduced A. Likewise if
1633 // P is a pointer to a class of the form simple-template-id, the
1634 // transformed A can be a pointer to a derived class pointed to by the
1637 // These alternatives are considered only if type deduction would
1638 // otherwise fail. If they yield more than one possible deduced A, the
1639 // type deduction fails.
1641 // Reset the incorrectly deduced argument from above.
1642 Deduced = DeducedOrig;
1644 // Use data recursion to crawl through the list of base classes.
1645 // Visited contains the set of nodes we have already visited, while
1646 // ToVisit is our stack of records that we still need to visit.
1647 llvm::SmallPtrSet<const RecordType *, 8> Visited;
1648 SmallVector<const RecordType *, 8> ToVisit;
1649 ToVisit.push_back(RecordT);
1650 bool Successful = false;
1651 SmallVector<DeducedTemplateArgument, 8> SuccessfulDeduced;
1652 while (!ToVisit.empty()) {
1653 // Retrieve the next class in the inheritance hierarchy.
1654 const RecordType *NextT = ToVisit.pop_back_val();
1656 // If we have already seen this type, skip it.
1657 if (!Visited.insert(NextT).second)
1660 // If this is a base class, try to perform template argument
1661 // deduction from it.
1662 if (NextT != RecordT) {
1663 TemplateDeductionInfo BaseInfo(Info.getLocation());
1664 Sema::TemplateDeductionResult BaseResult =
1665 DeduceTemplateArguments(S, TemplateParams, SpecParam,
1666 QualType(NextT, 0), BaseInfo, Deduced);
1668 // If template argument deduction for this base was successful,
1669 // note that we had some success. Otherwise, ignore any deductions
1670 // from this base class.
1671 if (BaseResult == Sema::TDK_Success) {
1672 // If we've already seen some success, then deduction fails due to
1673 // an ambiguity (temp.deduct.call p5).
1675 return Sema::TDK_MiscellaneousDeductionFailure;
1678 std::swap(SuccessfulDeduced, Deduced);
1680 Info.Param = BaseInfo.Param;
1681 Info.FirstArg = BaseInfo.FirstArg;
1682 Info.SecondArg = BaseInfo.SecondArg;
1685 Deduced = DeducedOrig;
1688 // Visit base classes
1689 CXXRecordDecl *Next = cast<CXXRecordDecl>(NextT->getDecl());
1690 for (const auto &Base : Next->bases()) {
1691 assert(Base.getType()->isRecordType() &&
1692 "Base class that isn't a record?");
1693 ToVisit.push_back(Base.getType()->getAs<RecordType>());
1698 std::swap(SuccessfulDeduced, Deduced);
1699 return Sema::TDK_Success;
1709 // type (type::*)(T)
1714 case Type::MemberPointer: {
1715 const MemberPointerType *MemPtrParam = cast<MemberPointerType>(Param);
1716 const MemberPointerType *MemPtrArg = dyn_cast<MemberPointerType>(Arg);
1718 return Sema::TDK_NonDeducedMismatch;
1720 QualType ParamPointeeType = MemPtrParam->getPointeeType();
1721 if (ParamPointeeType->isFunctionType())
1722 S.adjustMemberFunctionCC(ParamPointeeType, /*IsStatic=*/true,
1723 /*IsCtorOrDtor=*/false, Info.getLocation());
1724 QualType ArgPointeeType = MemPtrArg->getPointeeType();
1725 if (ArgPointeeType->isFunctionType())
1726 S.adjustMemberFunctionCC(ArgPointeeType, /*IsStatic=*/true,
1727 /*IsCtorOrDtor=*/false, Info.getLocation());
1729 if (Sema::TemplateDeductionResult Result
1730 = DeduceTemplateArgumentsByTypeMatch(S, TemplateParams,
1734 TDF & TDF_IgnoreQualifiers))
1737 return DeduceTemplateArgumentsByTypeMatch(S, TemplateParams,
1738 QualType(MemPtrParam->getClass(), 0),
1739 QualType(MemPtrArg->getClass(), 0),
1741 TDF & TDF_IgnoreQualifiers);
1744 // (clang extension)
1749 case Type::BlockPointer: {
1750 const BlockPointerType *BlockPtrParam = cast<BlockPointerType>(Param);
1751 const BlockPointerType *BlockPtrArg = dyn_cast<BlockPointerType>(Arg);
1754 return Sema::TDK_NonDeducedMismatch;
1756 return DeduceTemplateArgumentsByTypeMatch(S, TemplateParams,
1757 BlockPtrParam->getPointeeType(),
1758 BlockPtrArg->getPointeeType(),
1762 // (clang extension)
1764 // T __attribute__(((ext_vector_type(<integral constant>))))
1765 case Type::ExtVector: {
1766 const ExtVectorType *VectorParam = cast<ExtVectorType>(Param);
1767 if (const ExtVectorType *VectorArg = dyn_cast<ExtVectorType>(Arg)) {
1768 // Make sure that the vectors have the same number of elements.
1769 if (VectorParam->getNumElements() != VectorArg->getNumElements())
1770 return Sema::TDK_NonDeducedMismatch;
1772 // Perform deduction on the element types.
1773 return DeduceTemplateArgumentsByTypeMatch(S, TemplateParams,
1774 VectorParam->getElementType(),
1775 VectorArg->getElementType(),
1776 Info, Deduced, TDF);
1779 if (const DependentSizedExtVectorType *VectorArg
1780 = dyn_cast<DependentSizedExtVectorType>(Arg)) {
1781 // We can't check the number of elements, since the argument has a
1782 // dependent number of elements. This can only occur during partial
1785 // Perform deduction on the element types.
1786 return DeduceTemplateArgumentsByTypeMatch(S, TemplateParams,
1787 VectorParam->getElementType(),
1788 VectorArg->getElementType(),
1789 Info, Deduced, TDF);
1792 return Sema::TDK_NonDeducedMismatch;
1795 // (clang extension)
1797 // T __attribute__(((ext_vector_type(N))))
1798 case Type::DependentSizedExtVector: {
1799 const DependentSizedExtVectorType *VectorParam
1800 = cast<DependentSizedExtVectorType>(Param);
1802 if (const ExtVectorType *VectorArg = dyn_cast<ExtVectorType>(Arg)) {
1803 // Perform deduction on the element types.
1804 if (Sema::TemplateDeductionResult Result
1805 = DeduceTemplateArgumentsByTypeMatch(S, TemplateParams,
1806 VectorParam->getElementType(),
1807 VectorArg->getElementType(),
1808 Info, Deduced, TDF))
1811 // Perform deduction on the vector size, if we can.
1812 NonTypeTemplateParmDecl *NTTP
1813 = getDeducedParameterFromExpr(Info, VectorParam->getSizeExpr());
1815 return Sema::TDK_Success;
1817 llvm::APSInt ArgSize(S.Context.getTypeSize(S.Context.IntTy), false);
1818 ArgSize = VectorArg->getNumElements();
1819 // Note that we use the "array bound" rules here; just like in that
1820 // case, we don't have any particular type for the vector size, but
1821 // we can provide one if necessary.
1822 return DeduceNonTypeTemplateArgument(S, TemplateParams, NTTP, ArgSize,
1823 S.Context.IntTy, true, Info,
1827 if (const DependentSizedExtVectorType *VectorArg
1828 = dyn_cast<DependentSizedExtVectorType>(Arg)) {
1829 // Perform deduction on the element types.
1830 if (Sema::TemplateDeductionResult Result
1831 = DeduceTemplateArgumentsByTypeMatch(S, TemplateParams,
1832 VectorParam->getElementType(),
1833 VectorArg->getElementType(),
1834 Info, Deduced, TDF))
1837 // Perform deduction on the vector size, if we can.
1838 NonTypeTemplateParmDecl *NTTP
1839 = getDeducedParameterFromExpr(Info, VectorParam->getSizeExpr());
1841 return Sema::TDK_Success;
1843 return DeduceNonTypeTemplateArgument(S, TemplateParams, NTTP,
1844 VectorArg->getSizeExpr(),
1848 return Sema::TDK_NonDeducedMismatch;
1851 // (clang extension)
1853 // T __attribute__(((address_space(N))))
1854 case Type::DependentAddressSpace: {
1855 const DependentAddressSpaceType *AddressSpaceParam =
1856 cast<DependentAddressSpaceType>(Param);
1858 if (const DependentAddressSpaceType *AddressSpaceArg =
1859 dyn_cast<DependentAddressSpaceType>(Arg)) {
1860 // Perform deduction on the pointer type.
1861 if (Sema::TemplateDeductionResult Result =
1862 DeduceTemplateArgumentsByTypeMatch(
1863 S, TemplateParams, AddressSpaceParam->getPointeeType(),
1864 AddressSpaceArg->getPointeeType(), Info, Deduced, TDF))
1867 // Perform deduction on the address space, if we can.
1868 NonTypeTemplateParmDecl *NTTP = getDeducedParameterFromExpr(
1869 Info, AddressSpaceParam->getAddrSpaceExpr());
1871 return Sema::TDK_Success;
1873 return DeduceNonTypeTemplateArgument(
1874 S, TemplateParams, NTTP, AddressSpaceArg->getAddrSpaceExpr(), Info,
1878 if (isTargetAddressSpace(Arg.getAddressSpace())) {
1879 llvm::APSInt ArgAddressSpace(S.Context.getTypeSize(S.Context.IntTy),
1881 ArgAddressSpace = toTargetAddressSpace(Arg.getAddressSpace());
1883 // Perform deduction on the pointer types.
1884 if (Sema::TemplateDeductionResult Result =
1885 DeduceTemplateArgumentsByTypeMatch(
1886 S, TemplateParams, AddressSpaceParam->getPointeeType(),
1887 S.Context.removeAddrSpaceQualType(Arg), Info, Deduced, TDF))
1890 // Perform deduction on the address space, if we can.
1891 NonTypeTemplateParmDecl *NTTP = getDeducedParameterFromExpr(
1892 Info, AddressSpaceParam->getAddrSpaceExpr());
1894 return Sema::TDK_Success;
1896 return DeduceNonTypeTemplateArgument(S, TemplateParams, NTTP,
1897 ArgAddressSpace, S.Context.IntTy,
1898 true, Info, Deduced);
1901 return Sema::TDK_NonDeducedMismatch;
1904 case Type::TypeOfExpr:
1906 case Type::DependentName:
1907 case Type::UnresolvedUsing:
1908 case Type::Decltype:
1909 case Type::UnaryTransform:
1911 case Type::DeducedTemplateSpecialization:
1912 case Type::DependentTemplateSpecialization:
1913 case Type::PackExpansion:
1915 // No template argument deduction for these types
1916 return Sema::TDK_Success;
1919 llvm_unreachable("Invalid Type Class!");
1922 static Sema::TemplateDeductionResult
1923 DeduceTemplateArguments(Sema &S,
1924 TemplateParameterList *TemplateParams,
1925 const TemplateArgument &Param,
1926 TemplateArgument Arg,
1927 TemplateDeductionInfo &Info,
1928 SmallVectorImpl<DeducedTemplateArgument> &Deduced) {
1929 // If the template argument is a pack expansion, perform template argument
1930 // deduction against the pattern of that expansion. This only occurs during
1931 // partial ordering.
1932 if (Arg.isPackExpansion())
1933 Arg = Arg.getPackExpansionPattern();
1935 switch (Param.getKind()) {
1936 case TemplateArgument::Null:
1937 llvm_unreachable("Null template argument in parameter list");
1939 case TemplateArgument::Type:
1940 if (Arg.getKind() == TemplateArgument::Type)
1941 return DeduceTemplateArgumentsByTypeMatch(S, TemplateParams,
1945 Info.FirstArg = Param;
1946 Info.SecondArg = Arg;
1947 return Sema::TDK_NonDeducedMismatch;
1949 case TemplateArgument::Template:
1950 if (Arg.getKind() == TemplateArgument::Template)
1951 return DeduceTemplateArguments(S, TemplateParams,
1952 Param.getAsTemplate(),
1953 Arg.getAsTemplate(), Info, Deduced);
1954 Info.FirstArg = Param;
1955 Info.SecondArg = Arg;
1956 return Sema::TDK_NonDeducedMismatch;
1958 case TemplateArgument::TemplateExpansion:
1959 llvm_unreachable("caller should handle pack expansions");
1961 case TemplateArgument::Declaration:
1962 if (Arg.getKind() == TemplateArgument::Declaration &&
1963 isSameDeclaration(Param.getAsDecl(), Arg.getAsDecl()))
1964 return Sema::TDK_Success;
1966 Info.FirstArg = Param;
1967 Info.SecondArg = Arg;
1968 return Sema::TDK_NonDeducedMismatch;
1970 case TemplateArgument::NullPtr:
1971 if (Arg.getKind() == TemplateArgument::NullPtr &&
1972 S.Context.hasSameType(Param.getNullPtrType(), Arg.getNullPtrType()))
1973 return Sema::TDK_Success;
1975 Info.FirstArg = Param;
1976 Info.SecondArg = Arg;
1977 return Sema::TDK_NonDeducedMismatch;
1979 case TemplateArgument::Integral:
1980 if (Arg.getKind() == TemplateArgument::Integral) {
1981 if (hasSameExtendedValue(Param.getAsIntegral(), Arg.getAsIntegral()))
1982 return Sema::TDK_Success;
1984 Info.FirstArg = Param;
1985 Info.SecondArg = Arg;
1986 return Sema::TDK_NonDeducedMismatch;
1989 if (Arg.getKind() == TemplateArgument::Expression) {
1990 Info.FirstArg = Param;
1991 Info.SecondArg = Arg;
1992 return Sema::TDK_NonDeducedMismatch;
1995 Info.FirstArg = Param;
1996 Info.SecondArg = Arg;
1997 return Sema::TDK_NonDeducedMismatch;
1999 case TemplateArgument::Expression: {
2000 if (NonTypeTemplateParmDecl *NTTP
2001 = getDeducedParameterFromExpr(Info, Param.getAsExpr())) {
2002 if (Arg.getKind() == TemplateArgument::Integral)
2003 return DeduceNonTypeTemplateArgument(S, TemplateParams, NTTP,
2004 Arg.getAsIntegral(),
2005 Arg.getIntegralType(),
2006 /*ArrayBound=*/false,
2008 if (Arg.getKind() == TemplateArgument::NullPtr)
2009 return DeduceNullPtrTemplateArgument(S, TemplateParams, NTTP,
2010 Arg.getNullPtrType(),
2012 if (Arg.getKind() == TemplateArgument::Expression)
2013 return DeduceNonTypeTemplateArgument(S, TemplateParams, NTTP,
2014 Arg.getAsExpr(), Info, Deduced);
2015 if (Arg.getKind() == TemplateArgument::Declaration)
2016 return DeduceNonTypeTemplateArgument(S, TemplateParams, NTTP,
2018 Arg.getParamTypeForDecl(),
2021 Info.FirstArg = Param;
2022 Info.SecondArg = Arg;
2023 return Sema::TDK_NonDeducedMismatch;
2026 // Can't deduce anything, but that's okay.
2027 return Sema::TDK_Success;
2029 case TemplateArgument::Pack:
2030 llvm_unreachable("Argument packs should be expanded by the caller!");
2033 llvm_unreachable("Invalid TemplateArgument Kind!");
2036 /// \brief Determine whether there is a template argument to be used for
2039 /// This routine "expands" argument packs in-place, overriding its input
2040 /// parameters so that \c Args[ArgIdx] will be the available template argument.
2042 /// \returns true if there is another template argument (which will be at
2043 /// \c Args[ArgIdx]), false otherwise.
2044 static bool hasTemplateArgumentForDeduction(ArrayRef<TemplateArgument> &Args,
2046 if (ArgIdx == Args.size())
2049 const TemplateArgument &Arg = Args[ArgIdx];
2050 if (Arg.getKind() != TemplateArgument::Pack)
2053 assert(ArgIdx == Args.size() - 1 && "Pack not at the end of argument list?");
2054 Args = Arg.pack_elements();
2056 return ArgIdx < Args.size();
2059 /// \brief Determine whether the given set of template arguments has a pack
2060 /// expansion that is not the last template argument.
2061 static bool hasPackExpansionBeforeEnd(ArrayRef<TemplateArgument> Args) {
2062 bool FoundPackExpansion = false;
2063 for (const auto &A : Args) {
2064 if (FoundPackExpansion)
2067 if (A.getKind() == TemplateArgument::Pack)
2068 return hasPackExpansionBeforeEnd(A.pack_elements());
2070 if (A.isPackExpansion())
2071 FoundPackExpansion = true;
2077 static Sema::TemplateDeductionResult
2078 DeduceTemplateArguments(Sema &S, TemplateParameterList *TemplateParams,
2079 ArrayRef<TemplateArgument> Params,
2080 ArrayRef<TemplateArgument> Args,
2081 TemplateDeductionInfo &Info,
2082 SmallVectorImpl<DeducedTemplateArgument> &Deduced,
2083 bool NumberOfArgumentsMustMatch) {
2084 // C++0x [temp.deduct.type]p9:
2085 // If the template argument list of P contains a pack expansion that is not
2086 // the last template argument, the entire template argument list is a
2087 // non-deduced context.
2088 if (hasPackExpansionBeforeEnd(Params))
2089 return Sema::TDK_Success;
2091 // C++0x [temp.deduct.type]p9:
2092 // If P has a form that contains <T> or <i>, then each argument Pi of the
2093 // respective template argument list P is compared with the corresponding
2094 // argument Ai of the corresponding template argument list of A.
2095 unsigned ArgIdx = 0, ParamIdx = 0;
2096 for (; hasTemplateArgumentForDeduction(Params, ParamIdx); ++ParamIdx) {
2097 if (!Params[ParamIdx].isPackExpansion()) {
2098 // The simple case: deduce template arguments by matching Pi and Ai.
2100 // Check whether we have enough arguments.
2101 if (!hasTemplateArgumentForDeduction(Args, ArgIdx))
2102 return NumberOfArgumentsMustMatch
2103 ? Sema::TDK_MiscellaneousDeductionFailure
2104 : Sema::TDK_Success;
2106 // C++1z [temp.deduct.type]p9:
2107 // During partial ordering, if Ai was originally a pack expansion [and]
2108 // Pi is not a pack expansion, template argument deduction fails.
2109 if (Args[ArgIdx].isPackExpansion())
2110 return Sema::TDK_MiscellaneousDeductionFailure;
2112 // Perform deduction for this Pi/Ai pair.
2113 if (Sema::TemplateDeductionResult Result
2114 = DeduceTemplateArguments(S, TemplateParams,
2115 Params[ParamIdx], Args[ArgIdx],
2119 // Move to the next argument.
2124 // The parameter is a pack expansion.
2126 // C++0x [temp.deduct.type]p9:
2127 // If Pi is a pack expansion, then the pattern of Pi is compared with
2128 // each remaining argument in the template argument list of A. Each
2129 // comparison deduces template arguments for subsequent positions in the
2130 // template parameter packs expanded by Pi.
2131 TemplateArgument Pattern = Params[ParamIdx].getPackExpansionPattern();
2133 // FIXME: If there are no remaining arguments, we can bail out early
2134 // and set any deduced parameter packs to an empty argument pack.
2135 // The latter part of this is a (minor) correctness issue.
2137 // Prepare to deduce the packs within the pattern.
2138 PackDeductionScope PackScope(S, TemplateParams, Deduced, Info, Pattern);
2140 // Keep track of the deduced template arguments for each parameter pack
2141 // expanded by this pack expansion (the outer index) and for each
2142 // template argument (the inner SmallVectors).
2143 for (; hasTemplateArgumentForDeduction(Args, ArgIdx); ++ArgIdx) {
2144 // Deduce template arguments from the pattern.
2145 if (Sema::TemplateDeductionResult Result
2146 = DeduceTemplateArguments(S, TemplateParams, Pattern, Args[ArgIdx],
2150 PackScope.nextPackElement();
2153 // Build argument packs for each of the parameter packs expanded by this
2155 if (auto Result = PackScope.finish())
2159 return Sema::TDK_Success;
2162 static Sema::TemplateDeductionResult
2163 DeduceTemplateArguments(Sema &S,
2164 TemplateParameterList *TemplateParams,
2165 const TemplateArgumentList &ParamList,
2166 const TemplateArgumentList &ArgList,
2167 TemplateDeductionInfo &Info,
2168 SmallVectorImpl<DeducedTemplateArgument> &Deduced) {
2169 return DeduceTemplateArguments(S, TemplateParams, ParamList.asArray(),
2170 ArgList.asArray(), Info, Deduced,
2171 /*NumberOfArgumentsMustMatch*/false);
2174 /// \brief Determine whether two template arguments are the same.
2175 static bool isSameTemplateArg(ASTContext &Context,
2177 const TemplateArgument &Y,
2178 bool PackExpansionMatchesPack = false) {
2179 // If we're checking deduced arguments (X) against original arguments (Y),
2180 // we will have flattened packs to non-expansions in X.
2181 if (PackExpansionMatchesPack && X.isPackExpansion() && !Y.isPackExpansion())
2182 X = X.getPackExpansionPattern();
2184 if (X.getKind() != Y.getKind())
2187 switch (X.getKind()) {
2188 case TemplateArgument::Null:
2189 llvm_unreachable("Comparing NULL template argument");
2191 case TemplateArgument::Type:
2192 return Context.getCanonicalType(X.getAsType()) ==
2193 Context.getCanonicalType(Y.getAsType());
2195 case TemplateArgument::Declaration:
2196 return isSameDeclaration(X.getAsDecl(), Y.getAsDecl());
2198 case TemplateArgument::NullPtr:
2199 return Context.hasSameType(X.getNullPtrType(), Y.getNullPtrType());
2201 case TemplateArgument::Template:
2202 case TemplateArgument::TemplateExpansion:
2203 return Context.getCanonicalTemplateName(
2204 X.getAsTemplateOrTemplatePattern()).getAsVoidPointer() ==
2205 Context.getCanonicalTemplateName(
2206 Y.getAsTemplateOrTemplatePattern()).getAsVoidPointer();
2208 case TemplateArgument::Integral:
2209 return hasSameExtendedValue(X.getAsIntegral(), Y.getAsIntegral());
2211 case TemplateArgument::Expression: {
2212 llvm::FoldingSetNodeID XID, YID;
2213 X.getAsExpr()->Profile(XID, Context, true);
2214 Y.getAsExpr()->Profile(YID, Context, true);
2218 case TemplateArgument::Pack:
2219 if (X.pack_size() != Y.pack_size())
2222 for (TemplateArgument::pack_iterator XP = X.pack_begin(),
2223 XPEnd = X.pack_end(),
2224 YP = Y.pack_begin();
2225 XP != XPEnd; ++XP, ++YP)
2226 if (!isSameTemplateArg(Context, *XP, *YP, PackExpansionMatchesPack))
2232 llvm_unreachable("Invalid TemplateArgument Kind!");
2235 /// \brief Allocate a TemplateArgumentLoc where all locations have
2236 /// been initialized to the given location.
2238 /// \param Arg The template argument we are producing template argument
2239 /// location information for.
2241 /// \param NTTPType For a declaration template argument, the type of
2242 /// the non-type template parameter that corresponds to this template
2243 /// argument. Can be null if no type sugar is available to add to the
2244 /// type from the template argument.
2246 /// \param Loc The source location to use for the resulting template
2249 Sema::getTrivialTemplateArgumentLoc(const TemplateArgument &Arg,
2250 QualType NTTPType, SourceLocation Loc) {
2251 switch (Arg.getKind()) {
2252 case TemplateArgument::Null:
2253 llvm_unreachable("Can't get a NULL template argument here");
2255 case TemplateArgument::Type:
2256 return TemplateArgumentLoc(
2257 Arg, Context.getTrivialTypeSourceInfo(Arg.getAsType(), Loc));
2259 case TemplateArgument::Declaration: {
2260 if (NTTPType.isNull())
2261 NTTPType = Arg.getParamTypeForDecl();
2262 Expr *E = BuildExpressionFromDeclTemplateArgument(Arg, NTTPType, Loc)
2264 return TemplateArgumentLoc(TemplateArgument(E), E);
2267 case TemplateArgument::NullPtr: {
2268 if (NTTPType.isNull())
2269 NTTPType = Arg.getNullPtrType();
2270 Expr *E = BuildExpressionFromDeclTemplateArgument(Arg, NTTPType, Loc)
2272 return TemplateArgumentLoc(TemplateArgument(NTTPType, /*isNullPtr*/true),
2276 case TemplateArgument::Integral: {
2278 BuildExpressionFromIntegralTemplateArgument(Arg, Loc).getAs<Expr>();
2279 return TemplateArgumentLoc(TemplateArgument(E), E);
2282 case TemplateArgument::Template:
2283 case TemplateArgument::TemplateExpansion: {
2284 NestedNameSpecifierLocBuilder Builder;
2285 TemplateName Template = Arg.getAsTemplate();
2286 if (DependentTemplateName *DTN = Template.getAsDependentTemplateName())
2287 Builder.MakeTrivial(Context, DTN->getQualifier(), Loc);
2288 else if (QualifiedTemplateName *QTN =
2289 Template.getAsQualifiedTemplateName())
2290 Builder.MakeTrivial(Context, QTN->getQualifier(), Loc);
2292 if (Arg.getKind() == TemplateArgument::Template)
2293 return TemplateArgumentLoc(Arg, Builder.getWithLocInContext(Context),
2296 return TemplateArgumentLoc(Arg, Builder.getWithLocInContext(Context),
2300 case TemplateArgument::Expression:
2301 return TemplateArgumentLoc(Arg, Arg.getAsExpr());
2303 case TemplateArgument::Pack:
2304 return TemplateArgumentLoc(Arg, TemplateArgumentLocInfo());
2307 llvm_unreachable("Invalid TemplateArgument Kind!");
2311 /// \brief Convert the given deduced template argument and add it to the set of
2312 /// fully-converted template arguments.
2314 ConvertDeducedTemplateArgument(Sema &S, NamedDecl *Param,
2315 DeducedTemplateArgument Arg,
2316 NamedDecl *Template,
2317 TemplateDeductionInfo &Info,
2319 SmallVectorImpl<TemplateArgument> &Output) {
2320 auto ConvertArg = [&](DeducedTemplateArgument Arg,
2321 unsigned ArgumentPackIndex) {
2322 // Convert the deduced template argument into a template
2323 // argument that we can check, almost as if the user had written
2324 // the template argument explicitly.
2325 TemplateArgumentLoc ArgLoc =
2326 S.getTrivialTemplateArgumentLoc(Arg, QualType(), Info.getLocation());
2328 // Check the template argument, converting it as necessary.
2329 return S.CheckTemplateArgument(
2330 Param, ArgLoc, Template, Template->getLocation(),
2331 Template->getSourceRange().getEnd(), ArgumentPackIndex, Output,
2333 ? (Arg.wasDeducedFromArrayBound() ? Sema::CTAK_DeducedFromArrayBound
2334 : Sema::CTAK_Deduced)
2335 : Sema::CTAK_Specified);
2338 if (Arg.getKind() == TemplateArgument::Pack) {
2339 // This is a template argument pack, so check each of its arguments against
2340 // the template parameter.
2341 SmallVector<TemplateArgument, 2> PackedArgsBuilder;
2342 for (const auto &P : Arg.pack_elements()) {
2343 // When converting the deduced template argument, append it to the
2344 // general output list. We need to do this so that the template argument
2345 // checking logic has all of the prior template arguments available.
2346 DeducedTemplateArgument InnerArg(P);
2347 InnerArg.setDeducedFromArrayBound(Arg.wasDeducedFromArrayBound());
2348 assert(InnerArg.getKind() != TemplateArgument::Pack &&
2349 "deduced nested pack");
2351 // We deduced arguments for some elements of this pack, but not for
2352 // all of them. This happens if we get a conditionally-non-deduced
2353 // context in a pack expansion (such as an overload set in one of the
2355 S.Diag(Param->getLocation(),
2356 diag::err_template_arg_deduced_incomplete_pack)
2360 if (ConvertArg(InnerArg, PackedArgsBuilder.size()))
2363 // Move the converted template argument into our argument pack.
2364 PackedArgsBuilder.push_back(Output.pop_back_val());
2367 // If the pack is empty, we still need to substitute into the parameter
2368 // itself, in case that substitution fails.
2369 if (PackedArgsBuilder.empty()) {
2370 LocalInstantiationScope Scope(S);
2371 TemplateArgumentList TemplateArgs(TemplateArgumentList::OnStack, Output);
2372 MultiLevelTemplateArgumentList Args(TemplateArgs);
2374 if (auto *NTTP = dyn_cast<NonTypeTemplateParmDecl>(Param)) {
2375 Sema::InstantiatingTemplate Inst(S, Template->getLocation(), Template,
2377 Template->getSourceRange());
2378 if (Inst.isInvalid() ||
2379 S.SubstType(NTTP->getType(), Args, NTTP->getLocation(),
2380 NTTP->getDeclName()).isNull())
2382 } else if (auto *TTP = dyn_cast<TemplateTemplateParmDecl>(Param)) {
2383 Sema::InstantiatingTemplate Inst(S, Template->getLocation(), Template,
2385 Template->getSourceRange());
2386 if (Inst.isInvalid() || !S.SubstDecl(TTP, S.CurContext, Args))
2389 // For type parameters, no substitution is ever required.
2392 // Create the resulting argument pack.
2394 TemplateArgument::CreatePackCopy(S.Context, PackedArgsBuilder));
2398 return ConvertArg(Arg, 0);
2401 // FIXME: This should not be a template, but
2402 // ClassTemplatePartialSpecializationDecl sadly does not derive from
2404 template<typename TemplateDeclT>
2405 static Sema::TemplateDeductionResult ConvertDeducedTemplateArguments(
2406 Sema &S, TemplateDeclT *Template, bool IsDeduced,
2407 SmallVectorImpl<DeducedTemplateArgument> &Deduced,
2408 TemplateDeductionInfo &Info, SmallVectorImpl<TemplateArgument> &Builder,
2409 LocalInstantiationScope *CurrentInstantiationScope = nullptr,
2410 unsigned NumAlreadyConverted = 0, bool PartialOverloading = false) {
2411 TemplateParameterList *TemplateParams = Template->getTemplateParameters();
2413 for (unsigned I = 0, N = TemplateParams->size(); I != N; ++I) {
2414 NamedDecl *Param = TemplateParams->getParam(I);
2416 if (!Deduced[I].isNull()) {
2417 if (I < NumAlreadyConverted) {
2418 // We may have had explicitly-specified template arguments for a
2419 // template parameter pack (that may or may not have been extended
2420 // via additional deduced arguments).
2421 if (Param->isParameterPack() && CurrentInstantiationScope &&
2422 CurrentInstantiationScope->getPartiallySubstitutedPack() == Param) {
2423 // Forget the partially-substituted pack; its substitution is now
2425 CurrentInstantiationScope->ResetPartiallySubstitutedPack();
2426 // We still need to check the argument in case it was extended by
2429 // We have already fully type-checked and converted this
2430 // argument, because it was explicitly-specified. Just record the
2431 // presence of this argument.
2432 Builder.push_back(Deduced[I]);
2437 // We may have deduced this argument, so it still needs to be
2438 // checked and converted.
2439 if (ConvertDeducedTemplateArgument(S, Param, Deduced[I], Template, Info,
2440 IsDeduced, Builder)) {
2441 Info.Param = makeTemplateParameter(Param);
2442 // FIXME: These template arguments are temporary. Free them!
2443 Info.reset(TemplateArgumentList::CreateCopy(S.Context, Builder));
2444 return Sema::TDK_SubstitutionFailure;
2450 // C++0x [temp.arg.explicit]p3:
2451 // A trailing template parameter pack (14.5.3) not otherwise deduced will
2452 // be deduced to an empty sequence of template arguments.
2453 // FIXME: Where did the word "trailing" come from?
2454 if (Param->isTemplateParameterPack()) {
2455 // We may have had explicitly-specified template arguments for this
2456 // template parameter pack. If so, our empty deduction extends the
2457 // explicitly-specified set (C++0x [temp.arg.explicit]p9).
2458 const TemplateArgument *ExplicitArgs;
2459 unsigned NumExplicitArgs;
2460 if (CurrentInstantiationScope &&
2461 CurrentInstantiationScope->getPartiallySubstitutedPack(
2462 &ExplicitArgs, &NumExplicitArgs) == Param) {
2463 Builder.push_back(TemplateArgument(
2464 llvm::makeArrayRef(ExplicitArgs, NumExplicitArgs)));
2466 // Forget the partially-substituted pack; its substitution is now
2468 CurrentInstantiationScope->ResetPartiallySubstitutedPack();
2470 // Go through the motions of checking the empty argument pack against
2471 // the parameter pack.
2472 DeducedTemplateArgument DeducedPack(TemplateArgument::getEmptyPack());
2473 if (ConvertDeducedTemplateArgument(S, Param, DeducedPack, Template,
2474 Info, IsDeduced, Builder)) {
2475 Info.Param = makeTemplateParameter(Param);
2476 // FIXME: These template arguments are temporary. Free them!
2477 Info.reset(TemplateArgumentList::CreateCopy(S.Context, Builder));
2478 return Sema::TDK_SubstitutionFailure;
2484 // Substitute into the default template argument, if available.
2485 bool HasDefaultArg = false;
2486 TemplateDecl *TD = dyn_cast<TemplateDecl>(Template);
2488 assert(isa<ClassTemplatePartialSpecializationDecl>(Template) ||
2489 isa<VarTemplatePartialSpecializationDecl>(Template));
2490 return Sema::TDK_Incomplete;
2493 TemplateArgumentLoc DefArg = S.SubstDefaultTemplateArgumentIfAvailable(
2494 TD, TD->getLocation(), TD->getSourceRange().getEnd(), Param, Builder,
2497 // If there was no default argument, deduction is incomplete.
2498 if (DefArg.getArgument().isNull()) {
2499 Info.Param = makeTemplateParameter(
2500 const_cast<NamedDecl *>(TemplateParams->getParam(I)));
2501 Info.reset(TemplateArgumentList::CreateCopy(S.Context, Builder));
2502 if (PartialOverloading) break;
2504 return HasDefaultArg ? Sema::TDK_SubstitutionFailure
2505 : Sema::TDK_Incomplete;
2508 // Check whether we can actually use the default argument.
2509 if (S.CheckTemplateArgument(Param, DefArg, TD, TD->getLocation(),
2510 TD->getSourceRange().getEnd(), 0, Builder,
2511 Sema::CTAK_Specified)) {
2512 Info.Param = makeTemplateParameter(
2513 const_cast<NamedDecl *>(TemplateParams->getParam(I)));
2514 // FIXME: These template arguments are temporary. Free them!
2515 Info.reset(TemplateArgumentList::CreateCopy(S.Context, Builder));
2516 return Sema::TDK_SubstitutionFailure;
2519 // If we get here, we successfully used the default template argument.
2522 return Sema::TDK_Success;
2525 static DeclContext *getAsDeclContextOrEnclosing(Decl *D) {
2526 if (auto *DC = dyn_cast<DeclContext>(D))
2528 return D->getDeclContext();
2531 template<typename T> struct IsPartialSpecialization {
2532 static constexpr bool value = false;
2535 struct IsPartialSpecialization<ClassTemplatePartialSpecializationDecl> {
2536 static constexpr bool value = true;
2539 struct IsPartialSpecialization<VarTemplatePartialSpecializationDecl> {
2540 static constexpr bool value = true;
2543 /// Complete template argument deduction for a partial specialization.
2544 template <typename T>
2545 static typename std::enable_if<IsPartialSpecialization<T>::value,
2546 Sema::TemplateDeductionResult>::type
2547 FinishTemplateArgumentDeduction(
2548 Sema &S, T *Partial, bool IsPartialOrdering,
2549 const TemplateArgumentList &TemplateArgs,
2550 SmallVectorImpl<DeducedTemplateArgument> &Deduced,
2551 TemplateDeductionInfo &Info) {
2552 // Unevaluated SFINAE context.
2553 EnterExpressionEvaluationContext Unevaluated(
2554 S, Sema::ExpressionEvaluationContext::Unevaluated);
2555 Sema::SFINAETrap Trap(S);
2557 Sema::ContextRAII SavedContext(S, getAsDeclContextOrEnclosing(Partial));
2559 // C++ [temp.deduct.type]p2:
2560 // [...] or if any template argument remains neither deduced nor
2561 // explicitly specified, template argument deduction fails.
2562 SmallVector<TemplateArgument, 4> Builder;
2563 if (auto Result = ConvertDeducedTemplateArguments(
2564 S, Partial, IsPartialOrdering, Deduced, Info, Builder))
2567 // Form the template argument list from the deduced template arguments.
2568 TemplateArgumentList *DeducedArgumentList
2569 = TemplateArgumentList::CreateCopy(S.Context, Builder);
2571 Info.reset(DeducedArgumentList);
2573 // Substitute the deduced template arguments into the template
2574 // arguments of the class template partial specialization, and
2575 // verify that the instantiated template arguments are both valid
2576 // and are equivalent to the template arguments originally provided
2577 // to the class template.
2578 LocalInstantiationScope InstScope(S);
2579 auto *Template = Partial->getSpecializedTemplate();
2580 const ASTTemplateArgumentListInfo *PartialTemplArgInfo =
2581 Partial->getTemplateArgsAsWritten();
2582 const TemplateArgumentLoc *PartialTemplateArgs =
2583 PartialTemplArgInfo->getTemplateArgs();
2585 TemplateArgumentListInfo InstArgs(PartialTemplArgInfo->LAngleLoc,
2586 PartialTemplArgInfo->RAngleLoc);
2588 if (S.Subst(PartialTemplateArgs, PartialTemplArgInfo->NumTemplateArgs,
2589 InstArgs, MultiLevelTemplateArgumentList(*DeducedArgumentList))) {
2590 unsigned ArgIdx = InstArgs.size(), ParamIdx = ArgIdx;
2591 if (ParamIdx >= Partial->getTemplateParameters()->size())
2592 ParamIdx = Partial->getTemplateParameters()->size() - 1;
2594 Decl *Param = const_cast<NamedDecl *>(
2595 Partial->getTemplateParameters()->getParam(ParamIdx));
2596 Info.Param = makeTemplateParameter(Param);
2597 Info.FirstArg = PartialTemplateArgs[ArgIdx].getArgument();
2598 return Sema::TDK_SubstitutionFailure;
2601 SmallVector<TemplateArgument, 4> ConvertedInstArgs;
2602 if (S.CheckTemplateArgumentList(Template, Partial->getLocation(), InstArgs,
2603 false, ConvertedInstArgs))
2604 return Sema::TDK_SubstitutionFailure;
2606 TemplateParameterList *TemplateParams = Template->getTemplateParameters();
2607 for (unsigned I = 0, E = TemplateParams->size(); I != E; ++I) {
2608 TemplateArgument InstArg = ConvertedInstArgs.data()[I];
2609 if (!isSameTemplateArg(S.Context, TemplateArgs[I], InstArg)) {
2610 Info.Param = makeTemplateParameter(TemplateParams->getParam(I));
2611 Info.FirstArg = TemplateArgs[I];
2612 Info.SecondArg = InstArg;
2613 return Sema::TDK_NonDeducedMismatch;
2617 if (Trap.hasErrorOccurred())
2618 return Sema::TDK_SubstitutionFailure;
2620 return Sema::TDK_Success;
2623 /// Complete template argument deduction for a class or variable template,
2624 /// when partial ordering against a partial specialization.
2625 // FIXME: Factor out duplication with partial specialization version above.
2626 static Sema::TemplateDeductionResult FinishTemplateArgumentDeduction(
2627 Sema &S, TemplateDecl *Template, bool PartialOrdering,
2628 const TemplateArgumentList &TemplateArgs,
2629 SmallVectorImpl<DeducedTemplateArgument> &Deduced,
2630 TemplateDeductionInfo &Info) {
2631 // Unevaluated SFINAE context.
2632 EnterExpressionEvaluationContext Unevaluated(
2633 S, Sema::ExpressionEvaluationContext::Unevaluated);
2634 Sema::SFINAETrap Trap(S);
2636 Sema::ContextRAII SavedContext(S, getAsDeclContextOrEnclosing(Template));
2638 // C++ [temp.deduct.type]p2:
2639 // [...] or if any template argument remains neither deduced nor
2640 // explicitly specified, template argument deduction fails.
2641 SmallVector<TemplateArgument, 4> Builder;
2642 if (auto Result = ConvertDeducedTemplateArguments(
2643 S, Template, /*IsDeduced*/PartialOrdering, Deduced, Info, Builder))
2646 // Check that we produced the correct argument list.
2647 TemplateParameterList *TemplateParams = Template->getTemplateParameters();
2648 for (unsigned I = 0, E = TemplateParams->size(); I != E; ++I) {
2649 TemplateArgument InstArg = Builder[I];
2650 if (!isSameTemplateArg(S.Context, TemplateArgs[I], InstArg,
2651 /*PackExpansionMatchesPack*/true)) {
2652 Info.Param = makeTemplateParameter(TemplateParams->getParam(I));
2653 Info.FirstArg = TemplateArgs[I];
2654 Info.SecondArg = InstArg;
2655 return Sema::TDK_NonDeducedMismatch;
2659 if (Trap.hasErrorOccurred())
2660 return Sema::TDK_SubstitutionFailure;
2662 return Sema::TDK_Success;
2666 /// \brief Perform template argument deduction to determine whether
2667 /// the given template arguments match the given class template
2668 /// partial specialization per C++ [temp.class.spec.match].
2669 Sema::TemplateDeductionResult
2670 Sema::DeduceTemplateArguments(ClassTemplatePartialSpecializationDecl *Partial,
2671 const TemplateArgumentList &TemplateArgs,
2672 TemplateDeductionInfo &Info) {
2673 if (Partial->isInvalidDecl())
2676 // C++ [temp.class.spec.match]p2:
2677 // A partial specialization matches a given actual template
2678 // argument list if the template arguments of the partial
2679 // specialization can be deduced from the actual template argument
2682 // Unevaluated SFINAE context.
2683 EnterExpressionEvaluationContext Unevaluated(
2684 *this, Sema::ExpressionEvaluationContext::Unevaluated);
2685 SFINAETrap Trap(*this);
2687 SmallVector<DeducedTemplateArgument, 4> Deduced;
2688 Deduced.resize(Partial->getTemplateParameters()->size());
2689 if (TemplateDeductionResult Result
2690 = ::DeduceTemplateArguments(*this,
2691 Partial->getTemplateParameters(),
2692 Partial->getTemplateArgs(),
2693 TemplateArgs, Info, Deduced))
2696 SmallVector<TemplateArgument, 4> DeducedArgs(Deduced.begin(), Deduced.end());
2697 InstantiatingTemplate Inst(*this, Info.getLocation(), Partial, DeducedArgs,
2699 if (Inst.isInvalid())
2700 return TDK_InstantiationDepth;
2702 if (Trap.hasErrorOccurred())
2703 return Sema::TDK_SubstitutionFailure;
2705 return ::FinishTemplateArgumentDeduction(
2706 *this, Partial, /*PartialOrdering=*/false, TemplateArgs, Deduced, Info);
2709 /// \brief Perform template argument deduction to determine whether
2710 /// the given template arguments match the given variable template
2711 /// partial specialization per C++ [temp.class.spec.match].
2712 Sema::TemplateDeductionResult
2713 Sema::DeduceTemplateArguments(VarTemplatePartialSpecializationDecl *Partial,
2714 const TemplateArgumentList &TemplateArgs,
2715 TemplateDeductionInfo &Info) {
2716 if (Partial->isInvalidDecl())
2719 // C++ [temp.class.spec.match]p2:
2720 // A partial specialization matches a given actual template
2721 // argument list if the template arguments of the partial
2722 // specialization can be deduced from the actual template argument
2725 // Unevaluated SFINAE context.
2726 EnterExpressionEvaluationContext Unevaluated(
2727 *this, Sema::ExpressionEvaluationContext::Unevaluated);
2728 SFINAETrap Trap(*this);
2730 SmallVector<DeducedTemplateArgument, 4> Deduced;
2731 Deduced.resize(Partial->getTemplateParameters()->size());
2732 if (TemplateDeductionResult Result = ::DeduceTemplateArguments(
2733 *this, Partial->getTemplateParameters(), Partial->getTemplateArgs(),
2734 TemplateArgs, Info, Deduced))
2737 SmallVector<TemplateArgument, 4> DeducedArgs(Deduced.begin(), Deduced.end());
2738 InstantiatingTemplate Inst(*this, Info.getLocation(), Partial, DeducedArgs,
2740 if (Inst.isInvalid())
2741 return TDK_InstantiationDepth;
2743 if (Trap.hasErrorOccurred())
2744 return Sema::TDK_SubstitutionFailure;
2746 return ::FinishTemplateArgumentDeduction(
2747 *this, Partial, /*PartialOrdering=*/false, TemplateArgs, Deduced, Info);
2750 /// \brief Determine whether the given type T is a simple-template-id type.
2751 static bool isSimpleTemplateIdType(QualType T) {
2752 if (const TemplateSpecializationType *Spec
2753 = T->getAs<TemplateSpecializationType>())
2754 return Spec->getTemplateName().getAsTemplateDecl() != nullptr;
2756 // C++17 [temp.local]p2:
2757 // the injected-class-name [...] is equivalent to the template-name followed
2758 // by the template-arguments of the class template specialization or partial
2759 // specialization enclosed in <>
2760 // ... which means it's equivalent to a simple-template-id.
2762 // This only arises during class template argument deduction for a copy
2763 // deduction candidate, where it permits slicing.
2764 if (T->getAs<InjectedClassNameType>())
2770 /// \brief Substitute the explicitly-provided template arguments into the
2771 /// given function template according to C++ [temp.arg.explicit].
2773 /// \param FunctionTemplate the function template into which the explicit
2774 /// template arguments will be substituted.
2776 /// \param ExplicitTemplateArgs the explicitly-specified template
2779 /// \param Deduced the deduced template arguments, which will be populated
2780 /// with the converted and checked explicit template arguments.
2782 /// \param ParamTypes will be populated with the instantiated function
2785 /// \param FunctionType if non-NULL, the result type of the function template
2786 /// will also be instantiated and the pointed-to value will be updated with
2787 /// the instantiated function type.
2789 /// \param Info if substitution fails for any reason, this object will be
2790 /// populated with more information about the failure.
2792 /// \returns TDK_Success if substitution was successful, or some failure
2794 Sema::TemplateDeductionResult
2795 Sema::SubstituteExplicitTemplateArguments(
2796 FunctionTemplateDecl *FunctionTemplate,
2797 TemplateArgumentListInfo &ExplicitTemplateArgs,
2798 SmallVectorImpl<DeducedTemplateArgument> &Deduced,
2799 SmallVectorImpl<QualType> &ParamTypes,
2800 QualType *FunctionType,
2801 TemplateDeductionInfo &Info) {
2802 FunctionDecl *Function = FunctionTemplate->getTemplatedDecl();
2803 TemplateParameterList *TemplateParams
2804 = FunctionTemplate->getTemplateParameters();
2806 if (ExplicitTemplateArgs.size() == 0) {
2807 // No arguments to substitute; just copy over the parameter types and
2808 // fill in the function type.
2809 for (auto P : Function->parameters())
2810 ParamTypes.push_back(P->getType());
2813 *FunctionType = Function->getType();
2817 // Unevaluated SFINAE context.
2818 EnterExpressionEvaluationContext Unevaluated(
2819 *this, Sema::ExpressionEvaluationContext::Unevaluated);
2820 SFINAETrap Trap(*this);
2822 // C++ [temp.arg.explicit]p3:
2823 // Template arguments that are present shall be specified in the
2824 // declaration order of their corresponding template-parameters. The
2825 // template argument list shall not specify more template-arguments than
2826 // there are corresponding template-parameters.
2827 SmallVector<TemplateArgument, 4> Builder;
2829 // Enter a new template instantiation context where we check the
2830 // explicitly-specified template arguments against this function template,
2831 // and then substitute them into the function parameter types.
2832 SmallVector<TemplateArgument, 4> DeducedArgs;
2833 InstantiatingTemplate Inst(
2834 *this, Info.getLocation(), FunctionTemplate, DeducedArgs,
2835 CodeSynthesisContext::ExplicitTemplateArgumentSubstitution, Info);
2836 if (Inst.isInvalid())
2837 return TDK_InstantiationDepth;
2839 if (CheckTemplateArgumentList(FunctionTemplate, SourceLocation(),
2840 ExplicitTemplateArgs, true, Builder, false) ||
2841 Trap.hasErrorOccurred()) {
2842 unsigned Index = Builder.size();
2843 if (Index >= TemplateParams->size())
2844 Index = TemplateParams->size() - 1;
2845 Info.Param = makeTemplateParameter(TemplateParams->getParam(Index));
2846 return TDK_InvalidExplicitArguments;
2849 // Form the template argument list from the explicitly-specified
2850 // template arguments.
2851 TemplateArgumentList *ExplicitArgumentList
2852 = TemplateArgumentList::CreateCopy(Context, Builder);
2853 Info.reset(ExplicitArgumentList);
2855 // Template argument deduction and the final substitution should be
2856 // done in the context of the templated declaration. Explicit
2857 // argument substitution, on the other hand, needs to happen in the
2859 ContextRAII SavedContext(*this, FunctionTemplate->getTemplatedDecl());
2861 // If we deduced template arguments for a template parameter pack,
2862 // note that the template argument pack is partially substituted and record
2863 // the explicit template arguments. They'll be used as part of deduction
2864 // for this template parameter pack.
2865 for (unsigned I = 0, N = Builder.size(); I != N; ++I) {
2866 const TemplateArgument &Arg = Builder[I];
2867 if (Arg.getKind() == TemplateArgument::Pack) {
2868 CurrentInstantiationScope->SetPartiallySubstitutedPack(
2869 TemplateParams->getParam(I),
2876 const FunctionProtoType *Proto
2877 = Function->getType()->getAs<FunctionProtoType>();
2878 assert(Proto && "Function template does not have a prototype?");
2880 // Isolate our substituted parameters from our caller.
2881 LocalInstantiationScope InstScope(*this, /*MergeWithOuterScope*/true);
2883 ExtParameterInfoBuilder ExtParamInfos;
2885 // Instantiate the types of each of the function parameters given the
2886 // explicitly-specified template arguments. If the function has a trailing
2887 // return type, substitute it after the arguments to ensure we substitute
2888 // in lexical order.
2889 if (Proto->hasTrailingReturn()) {
2890 if (SubstParmTypes(Function->getLocation(), Function->parameters(),
2891 Proto->getExtParameterInfosOrNull(),
2892 MultiLevelTemplateArgumentList(*ExplicitArgumentList),
2893 ParamTypes, /*params*/ nullptr, ExtParamInfos))
2894 return TDK_SubstitutionFailure;
2897 // Instantiate the return type.
2898 QualType ResultType;
2900 // C++11 [expr.prim.general]p3:
2901 // If a declaration declares a member function or member function
2902 // template of a class X, the expression this is a prvalue of type
2903 // "pointer to cv-qualifier-seq X" between the optional cv-qualifer-seq
2904 // and the end of the function-definition, member-declarator, or
2906 unsigned ThisTypeQuals = 0;
2907 CXXRecordDecl *ThisContext = nullptr;
2908 if (CXXMethodDecl *Method = dyn_cast<CXXMethodDecl>(Function)) {
2909 ThisContext = Method->getParent();
2910 ThisTypeQuals = Method->getTypeQualifiers();
2913 CXXThisScopeRAII ThisScope(*this, ThisContext, ThisTypeQuals,
2914 getLangOpts().CPlusPlus11);
2917 SubstType(Proto->getReturnType(),
2918 MultiLevelTemplateArgumentList(*ExplicitArgumentList),
2919 Function->getTypeSpecStartLoc(), Function->getDeclName());
2920 if (ResultType.isNull() || Trap.hasErrorOccurred())
2921 return TDK_SubstitutionFailure;
2924 // Instantiate the types of each of the function parameters given the
2925 // explicitly-specified template arguments if we didn't do so earlier.
2926 if (!Proto->hasTrailingReturn() &&
2927 SubstParmTypes(Function->getLocation(), Function->parameters(),
2928 Proto->getExtParameterInfosOrNull(),
2929 MultiLevelTemplateArgumentList(*ExplicitArgumentList),
2930 ParamTypes, /*params*/ nullptr, ExtParamInfos))
2931 return TDK_SubstitutionFailure;
2934 auto EPI = Proto->getExtProtoInfo();
2935 EPI.ExtParameterInfos = ExtParamInfos.getPointerOrNull(ParamTypes.size());
2937 // In C++1z onwards, exception specifications are part of the function type,
2938 // so substitution into the type must also substitute into the exception
2940 SmallVector<QualType, 4> ExceptionStorage;
2941 if (getLangOpts().CPlusPlus17 &&
2943 Function->getLocation(), EPI.ExceptionSpec, ExceptionStorage,
2944 MultiLevelTemplateArgumentList(*ExplicitArgumentList)))
2945 return TDK_SubstitutionFailure;
2947 *FunctionType = BuildFunctionType(ResultType, ParamTypes,
2948 Function->getLocation(),
2949 Function->getDeclName(),
2951 if (FunctionType->isNull() || Trap.hasErrorOccurred())
2952 return TDK_SubstitutionFailure;
2955 // C++ [temp.arg.explicit]p2:
2956 // Trailing template arguments that can be deduced (14.8.2) may be
2957 // omitted from the list of explicit template-arguments. If all of the
2958 // template arguments can be deduced, they may all be omitted; in this
2959 // case, the empty template argument list <> itself may also be omitted.
2961 // Take all of the explicitly-specified arguments and put them into
2962 // the set of deduced template arguments. Explicitly-specified
2963 // parameter packs, however, will be set to NULL since the deduction
2964 // mechanisms handle explicitly-specified argument packs directly.
2965 Deduced.reserve(TemplateParams->size());
2966 for (unsigned I = 0, N = ExplicitArgumentList->size(); I != N; ++I) {
2967 const TemplateArgument &Arg = ExplicitArgumentList->get(I);
2968 if (Arg.getKind() == TemplateArgument::Pack)
2969 Deduced.push_back(DeducedTemplateArgument());
2971 Deduced.push_back(Arg);
2977 /// \brief Check whether the deduced argument type for a call to a function
2978 /// template matches the actual argument type per C++ [temp.deduct.call]p4.
2979 static Sema::TemplateDeductionResult
2980 CheckOriginalCallArgDeduction(Sema &S, TemplateDeductionInfo &Info,
2981 Sema::OriginalCallArg OriginalArg,
2982 QualType DeducedA) {
2983 ASTContext &Context = S.Context;
2985 auto Failed = [&]() -> Sema::TemplateDeductionResult {
2986 Info.FirstArg = TemplateArgument(DeducedA);
2987 Info.SecondArg = TemplateArgument(OriginalArg.OriginalArgType);
2988 Info.CallArgIndex = OriginalArg.ArgIdx;
2989 return OriginalArg.DecomposedParam ? Sema::TDK_DeducedMismatchNested
2990 : Sema::TDK_DeducedMismatch;
2993 QualType A = OriginalArg.OriginalArgType;
2994 QualType OriginalParamType = OriginalArg.OriginalParamType;
2996 // Check for type equality (top-level cv-qualifiers are ignored).
2997 if (Context.hasSameUnqualifiedType(A, DeducedA))
2998 return Sema::TDK_Success;
3000 // Strip off references on the argument types; they aren't needed for
3001 // the following checks.
3002 if (const ReferenceType *DeducedARef = DeducedA->getAs<ReferenceType>())
3003 DeducedA = DeducedARef->getPointeeType();
3004 if (const ReferenceType *ARef = A->getAs<ReferenceType>())
3005 A = ARef->getPointeeType();
3007 // C++ [temp.deduct.call]p4:
3008 // [...] However, there are three cases that allow a difference:
3009 // - If the original P is a reference type, the deduced A (i.e., the
3010 // type referred to by the reference) can be more cv-qualified than
3011 // the transformed A.
3012 if (const ReferenceType *OriginalParamRef
3013 = OriginalParamType->getAs<ReferenceType>()) {
3014 // We don't want to keep the reference around any more.
3015 OriginalParamType = OriginalParamRef->getPointeeType();
3017 // FIXME: Resolve core issue (no number yet): if the original P is a
3018 // reference type and the transformed A is function type "noexcept F",
3019 // the deduced A can be F.
3021 if (A->isFunctionType() && S.IsFunctionConversion(A, DeducedA, Tmp))
3022 return Sema::TDK_Success;
3024 Qualifiers AQuals = A.getQualifiers();
3025 Qualifiers DeducedAQuals = DeducedA.getQualifiers();
3027 // Under Objective-C++ ARC, the deduced type may have implicitly
3028 // been given strong or (when dealing with a const reference)
3029 // unsafe_unretained lifetime. If so, update the original
3030 // qualifiers to include this lifetime.
3031 if (S.getLangOpts().ObjCAutoRefCount &&
3032 ((DeducedAQuals.getObjCLifetime() == Qualifiers::OCL_Strong &&
3033 AQuals.getObjCLifetime() == Qualifiers::OCL_None) ||
3034 (DeducedAQuals.hasConst() &&
3035 DeducedAQuals.getObjCLifetime() == Qualifiers::OCL_ExplicitNone))) {
3036 AQuals.setObjCLifetime(DeducedAQuals.getObjCLifetime());
3039 if (AQuals == DeducedAQuals) {
3040 // Qualifiers match; there's nothing to do.
3041 } else if (!DeducedAQuals.compatiblyIncludes(AQuals)) {
3044 // Qualifiers are compatible, so have the argument type adopt the
3045 // deduced argument type's qualifiers as if we had performed the
3046 // qualification conversion.
3047 A = Context.getQualifiedType(A.getUnqualifiedType(), DeducedAQuals);
3051 // - The transformed A can be another pointer or pointer to member
3052 // type that can be converted to the deduced A via a function pointer
3053 // conversion and/or a qualification conversion.
3055 // Also allow conversions which merely strip __attribute__((noreturn)) from
3056 // function types (recursively).
3057 bool ObjCLifetimeConversion = false;
3059 if ((A->isAnyPointerType() || A->isMemberPointerType()) &&
3060 (S.IsQualificationConversion(A, DeducedA, false,
3061 ObjCLifetimeConversion) ||
3062 S.IsFunctionConversion(A, DeducedA, ResultTy)))
3063 return Sema::TDK_Success;
3065 // - If P is a class and P has the form simple-template-id, then the
3066 // transformed A can be a derived class of the deduced A. [...]
3067 // [...] Likewise, if P is a pointer to a class of the form
3068 // simple-template-id, the transformed A can be a pointer to a
3069 // derived class pointed to by the deduced A.
3070 if (const PointerType *OriginalParamPtr
3071 = OriginalParamType->getAs<PointerType>()) {
3072 if (const PointerType *DeducedAPtr = DeducedA->getAs<PointerType>()) {
3073 if (const PointerType *APtr = A->getAs<PointerType>()) {
3074 if (A->getPointeeType()->isRecordType()) {
3075 OriginalParamType = OriginalParamPtr->getPointeeType();
3076 DeducedA = DeducedAPtr->getPointeeType();
3077 A = APtr->getPointeeType();
3083 if (Context.hasSameUnqualifiedType(A, DeducedA))
3084 return Sema::TDK_Success;
3086 if (A->isRecordType() && isSimpleTemplateIdType(OriginalParamType) &&
3087 S.IsDerivedFrom(SourceLocation(), A, DeducedA))
3088 return Sema::TDK_Success;
3093 /// Find the pack index for a particular parameter index in an instantiation of
3094 /// a function template with specific arguments.
3096 /// \return The pack index for whichever pack produced this parameter, or -1
3097 /// if this was not produced by a parameter. Intended to be used as the
3098 /// ArgumentPackSubstitutionIndex for further substitutions.
3099 // FIXME: We should track this in OriginalCallArgs so we don't need to
3100 // reconstruct it here.
3101 static unsigned getPackIndexForParam(Sema &S,
3102 FunctionTemplateDecl *FunctionTemplate,
3103 const MultiLevelTemplateArgumentList &Args,
3104 unsigned ParamIdx) {
3106 for (auto *PD : FunctionTemplate->getTemplatedDecl()->parameters()) {
3107 if (PD->isParameterPack()) {
3108 unsigned NumExpansions =
3109 S.getNumArgumentsInExpansion(PD->getType(), Args).getValueOr(1);
3110 if (Idx + NumExpansions > ParamIdx)
3111 return ParamIdx - Idx;
3112 Idx += NumExpansions;
3114 if (Idx == ParamIdx)
3115 return -1; // Not a pack expansion
3120 llvm_unreachable("parameter index would not be produced from template");
3123 /// \brief Finish template argument deduction for a function template,
3124 /// checking the deduced template arguments for completeness and forming
3125 /// the function template specialization.
3127 /// \param OriginalCallArgs If non-NULL, the original call arguments against
3128 /// which the deduced argument types should be compared.
3129 Sema::TemplateDeductionResult Sema::FinishTemplateArgumentDeduction(
3130 FunctionTemplateDecl *FunctionTemplate,
3131 SmallVectorImpl<DeducedTemplateArgument> &Deduced,
3132 unsigned NumExplicitlySpecified, FunctionDecl *&Specialization,
3133 TemplateDeductionInfo &Info,
3134 SmallVectorImpl<OriginalCallArg> const *OriginalCallArgs,
3135 bool PartialOverloading, llvm::function_ref<bool()> CheckNonDependent) {
3136 // Unevaluated SFINAE context.
3137 EnterExpressionEvaluationContext Unevaluated(
3138 *this, Sema::ExpressionEvaluationContext::Unevaluated);
3139 SFINAETrap Trap(*this);
3141 // Enter a new template instantiation context while we instantiate the
3142 // actual function declaration.
3143 SmallVector<TemplateArgument, 4> DeducedArgs(Deduced.begin(), Deduced.end());
3144 InstantiatingTemplate Inst(
3145 *this, Info.getLocation(), FunctionTemplate, DeducedArgs,
3146 CodeSynthesisContext::DeducedTemplateArgumentSubstitution, Info);
3147 if (Inst.isInvalid())
3148 return TDK_InstantiationDepth;
3150 ContextRAII SavedContext(*this, FunctionTemplate->getTemplatedDecl());
3152 // C++ [temp.deduct.type]p2:
3153 // [...] or if any template argument remains neither deduced nor
3154 // explicitly specified, template argument deduction fails.
3155 SmallVector<TemplateArgument, 4> Builder;
3156 if (auto Result = ConvertDeducedTemplateArguments(
3157 *this, FunctionTemplate, /*IsDeduced*/true, Deduced, Info, Builder,
3158 CurrentInstantiationScope, NumExplicitlySpecified,
3159 PartialOverloading))
3162 // C++ [temp.deduct.call]p10: [DR1391]
3163 // If deduction succeeds for all parameters that contain
3164 // template-parameters that participate in template argument deduction,
3165 // and all template arguments are explicitly specified, deduced, or
3166 // obtained from default template arguments, remaining parameters are then
3167 // compared with the corresponding arguments. For each remaining parameter
3168 // P with a type that was non-dependent before substitution of any
3169 // explicitly-specified template arguments, if the corresponding argument
3170 // A cannot be implicitly converted to P, deduction fails.
3171 if (CheckNonDependent())
3172 return TDK_NonDependentConversionFailure;
3174 // Form the template argument list from the deduced template arguments.
3175 TemplateArgumentList *DeducedArgumentList
3176 = TemplateArgumentList::CreateCopy(Context, Builder);
3177 Info.reset(DeducedArgumentList);
3179 // Substitute the deduced template arguments into the function template
3180 // declaration to produce the function template specialization.
3181 DeclContext *Owner = FunctionTemplate->getDeclContext();
3182 if (FunctionTemplate->getFriendObjectKind())
3183 Owner = FunctionTemplate->getLexicalDeclContext();
3184 MultiLevelTemplateArgumentList SubstArgs(*DeducedArgumentList);
3185 Specialization = cast_or_null<FunctionDecl>(
3186 SubstDecl(FunctionTemplate->getTemplatedDecl(), Owner, SubstArgs));
3187 if (!Specialization || Specialization->isInvalidDecl())
3188 return TDK_SubstitutionFailure;
3190 assert(Specialization->getPrimaryTemplate()->getCanonicalDecl() ==
3191 FunctionTemplate->getCanonicalDecl());
3193 // If the template argument list is owned by the function template
3194 // specialization, release it.
3195 if (Specialization->getTemplateSpecializationArgs() == DeducedArgumentList &&
3196 !Trap.hasErrorOccurred())
3199 // There may have been an error that did not prevent us from constructing a
3200 // declaration. Mark the declaration invalid and return with a substitution
3202 if (Trap.hasErrorOccurred()) {
3203 Specialization->setInvalidDecl(true);
3204 return TDK_SubstitutionFailure;
3207 if (OriginalCallArgs) {
3208 // C++ [temp.deduct.call]p4:
3209 // In general, the deduction process attempts to find template argument
3210 // values that will make the deduced A identical to A (after the type A
3211 // is transformed as described above). [...]
3212 llvm::SmallDenseMap<std::pair<unsigned, QualType>, QualType> DeducedATypes;
3213 for (unsigned I = 0, N = OriginalCallArgs->size(); I != N; ++I) {
3214 OriginalCallArg OriginalArg = (*OriginalCallArgs)[I];
3216 auto ParamIdx = OriginalArg.ArgIdx;
3217 if (ParamIdx >= Specialization->getNumParams())
3218 // FIXME: This presumably means a pack ended up smaller than we
3219 // expected while deducing. Should this not result in deduction
3220 // failure? Can it even happen?
3224 if (!OriginalArg.DecomposedParam) {
3225 // P is one of the function parameters, just look up its substituted
3227 DeducedA = Specialization->getParamDecl(ParamIdx)->getType();
3229 // P is a decomposed element of a parameter corresponding to a
3230 // braced-init-list argument. Substitute back into P to find the
3232 QualType &CacheEntry =
3233 DeducedATypes[{ParamIdx, OriginalArg.OriginalParamType}];
3234 if (CacheEntry.isNull()) {
3235 ArgumentPackSubstitutionIndexRAII PackIndex(
3236 *this, getPackIndexForParam(*this, FunctionTemplate, SubstArgs,
3239 SubstType(OriginalArg.OriginalParamType, SubstArgs,
3240 Specialization->getTypeSpecStartLoc(),
3241 Specialization->getDeclName());
3243 DeducedA = CacheEntry;
3247 CheckOriginalCallArgDeduction(*this, Info, OriginalArg, DeducedA))
3252 // If we suppressed any diagnostics while performing template argument
3253 // deduction, and if we haven't already instantiated this declaration,
3254 // keep track of these diagnostics. They'll be emitted if this specialization
3255 // is actually used.
3256 if (Info.diag_begin() != Info.diag_end()) {
3257 SuppressedDiagnosticsMap::iterator
3258 Pos = SuppressedDiagnostics.find(Specialization->getCanonicalDecl());
3259 if (Pos == SuppressedDiagnostics.end())
3260 SuppressedDiagnostics[Specialization->getCanonicalDecl()]
3261 .append(Info.diag_begin(), Info.diag_end());
3267 /// Gets the type of a function for template-argument-deducton
3268 /// purposes when it's considered as part of an overload set.
3269 static QualType GetTypeOfFunction(Sema &S, const OverloadExpr::FindResult &R,
3271 // We may need to deduce the return type of the function now.
3272 if (S.getLangOpts().CPlusPlus14 && Fn->getReturnType()->isUndeducedType() &&
3273 S.DeduceReturnType(Fn, R.Expression->getExprLoc(), /*Diagnose*/ false))
3276 if (CXXMethodDecl *Method = dyn_cast<CXXMethodDecl>(Fn))
3277 if (Method->isInstance()) {
3278 // An instance method that's referenced in a form that doesn't
3279 // look like a member pointer is just invalid.
3280 if (!R.HasFormOfMemberPointer) return QualType();
3282 return S.Context.getMemberPointerType(Fn->getType(),
3283 S.Context.getTypeDeclType(Method->getParent()).getTypePtr());
3286 if (!R.IsAddressOfOperand) return Fn->getType();
3287 return S.Context.getPointerType(Fn->getType());
3290 /// Apply the deduction rules for overload sets.
3292 /// \return the null type if this argument should be treated as an
3293 /// undeduced context
3295 ResolveOverloadForDeduction(Sema &S, TemplateParameterList *TemplateParams,
3296 Expr *Arg, QualType ParamType,
3297 bool ParamWasReference) {
3299 OverloadExpr::FindResult R = OverloadExpr::find(Arg);
3301 OverloadExpr *Ovl = R.Expression;
3303 // C++0x [temp.deduct.call]p4
3305 if (ParamWasReference)
3306 TDF |= TDF_ParamWithReferenceType;
3307 if (R.IsAddressOfOperand)
3308 TDF |= TDF_IgnoreQualifiers;
3310 // C++0x [temp.deduct.call]p6:
3311 // When P is a function type, pointer to function type, or pointer
3312 // to member function type:
3314 if (!ParamType->isFunctionType() &&
3315 !ParamType->isFunctionPointerType() &&
3316 !ParamType->isMemberFunctionPointerType()) {
3317 if (Ovl->hasExplicitTemplateArgs()) {
3318 // But we can still look for an explicit specialization.
3319 if (FunctionDecl *ExplicitSpec
3320 = S.ResolveSingleFunctionTemplateSpecialization(Ovl))
3321 return GetTypeOfFunction(S, R, ExplicitSpec);
3325 if (FunctionDecl *Viable =
3326 S.resolveAddressOfOnlyViableOverloadCandidate(Arg, DAP))
3327 return GetTypeOfFunction(S, R, Viable);
3332 // Gather the explicit template arguments, if any.
3333 TemplateArgumentListInfo ExplicitTemplateArgs;
3334 if (Ovl->hasExplicitTemplateArgs())
3335 Ovl->copyTemplateArgumentsInto(ExplicitTemplateArgs);
3337 for (UnresolvedSetIterator I = Ovl->decls_begin(),
3338 E = Ovl->decls_end(); I != E; ++I) {
3339 NamedDecl *D = (*I)->getUnderlyingDecl();
3341 if (FunctionTemplateDecl *FunTmpl = dyn_cast<FunctionTemplateDecl>(D)) {
3342 // - If the argument is an overload set containing one or more
3343 // function templates, the parameter is treated as a
3344 // non-deduced context.
3345 if (!Ovl->hasExplicitTemplateArgs())
3348 // Otherwise, see if we can resolve a function type
3349 FunctionDecl *Specialization = nullptr;
3350 TemplateDeductionInfo Info(Ovl->getNameLoc());
3351 if (S.DeduceTemplateArguments(FunTmpl, &ExplicitTemplateArgs,
3352 Specialization, Info))
3358 FunctionDecl *Fn = cast<FunctionDecl>(D);
3359 QualType ArgType = GetTypeOfFunction(S, R, Fn);
3360 if (ArgType.isNull()) continue;
3362 // Function-to-pointer conversion.
3363 if (!ParamWasReference && ParamType->isPointerType() &&
3364 ArgType->isFunctionType())
3365 ArgType = S.Context.getPointerType(ArgType);
3367 // - If the argument is an overload set (not containing function
3368 // templates), trial argument deduction is attempted using each
3369 // of the members of the set. If deduction succeeds for only one
3370 // of the overload set members, that member is used as the
3371 // argument value for the deduction. If deduction succeeds for
3372 // more than one member of the overload set the parameter is
3373 // treated as a non-deduced context.
3375 // We do all of this in a fresh context per C++0x [temp.deduct.type]p2:
3376 // Type deduction is done independently for each P/A pair, and
3377 // the deduced template argument values are then combined.
3378 // So we do not reject deductions which were made elsewhere.
3379 SmallVector<DeducedTemplateArgument, 8>
3380 Deduced(TemplateParams->size());
3381 TemplateDeductionInfo Info(Ovl->getNameLoc());
3382 Sema::TemplateDeductionResult Result
3383 = DeduceTemplateArgumentsByTypeMatch(S, TemplateParams, ParamType,
3384 ArgType, Info, Deduced, TDF);
3385 if (Result) continue;
3386 if (!Match.isNull()) return QualType();
3393 /// \brief Perform the adjustments to the parameter and argument types
3394 /// described in C++ [temp.deduct.call].
3396 /// \returns true if the caller should not attempt to perform any template
3397 /// argument deduction based on this P/A pair because the argument is an
3398 /// overloaded function set that could not be resolved.
3399 static bool AdjustFunctionParmAndArgTypesForDeduction(
3400 Sema &S, TemplateParameterList *TemplateParams, unsigned FirstInnerIndex,
3401 QualType &ParamType, QualType &ArgType, Expr *Arg, unsigned &TDF) {
3402 // C++0x [temp.deduct.call]p3:
3403 // If P is a cv-qualified type, the top level cv-qualifiers of P's type
3404 // are ignored for type deduction.
3405 if (ParamType.hasQualifiers())
3406 ParamType = ParamType.getUnqualifiedType();
3408 // [...] If P is a reference type, the type referred to by P is
3409 // used for type deduction.
3410 const ReferenceType *ParamRefType = ParamType->getAs<ReferenceType>();
3412 ParamType = ParamRefType->getPointeeType();
3414 // Overload sets usually make this parameter an undeduced context,
3415 // but there are sometimes special circumstances. Typically
3416 // involving a template-id-expr.
3417 if (ArgType == S.Context.OverloadTy) {
3418 ArgType = ResolveOverloadForDeduction(S, TemplateParams,
3420 ParamRefType != nullptr);
3421 if (ArgType.isNull())
3426 // If the argument has incomplete array type, try to complete its type.
3427 if (ArgType->isIncompleteArrayType()) {
3428 S.completeExprArrayBound(Arg);
3429 ArgType = Arg->getType();
3432 // C++1z [temp.deduct.call]p3:
3433 // If P is a forwarding reference and the argument is an lvalue, the type
3434 // "lvalue reference to A" is used in place of A for type deduction.
3435 if (isForwardingReference(QualType(ParamRefType, 0), FirstInnerIndex) &&
3437 ArgType = S.Context.getLValueReferenceType(ArgType);
3439 // C++ [temp.deduct.call]p2:
3440 // If P is not a reference type:
3441 // - If A is an array type, the pointer type produced by the
3442 // array-to-pointer standard conversion (4.2) is used in place of
3443 // A for type deduction; otherwise,
3444 if (ArgType->isArrayType())
3445 ArgType = S.Context.getArrayDecayedType(ArgType);
3446 // - If A is a function type, the pointer type produced by the
3447 // function-to-pointer standard conversion (4.3) is used in place
3448 // of A for type deduction; otherwise,
3449 else if (ArgType->isFunctionType())
3450 ArgType = S.Context.getPointerType(ArgType);
3452 // - If A is a cv-qualified type, the top level cv-qualifiers of A's
3453 // type are ignored for type deduction.
3454 ArgType = ArgType.getUnqualifiedType();
3458 // C++0x [temp.deduct.call]p4:
3459 // In general, the deduction process attempts to find template argument
3460 // values that will make the deduced A identical to A (after the type A
3461 // is transformed as described above). [...]
3462 TDF = TDF_SkipNonDependent;
3464 // - If the original P is a reference type, the deduced A (i.e., the
3465 // type referred to by the reference) can be more cv-qualified than
3466 // the transformed A.
3468 TDF |= TDF_ParamWithReferenceType;
3469 // - The transformed A can be another pointer or pointer to member
3470 // type that can be converted to the deduced A via a qualification
3471 // conversion (4.4).
3472 if (ArgType->isPointerType() || ArgType->isMemberPointerType() ||
3473 ArgType->isObjCObjectPointerType())
3474 TDF |= TDF_IgnoreQualifiers;
3475 // - If P is a class and P has the form simple-template-id, then the
3476 // transformed A can be a derived class of the deduced A. Likewise,
3477 // if P is a pointer to a class of the form simple-template-id, the
3478 // transformed A can be a pointer to a derived class pointed to by
3480 if (isSimpleTemplateIdType(ParamType) ||
3481 (isa<PointerType>(ParamType) &&
3482 isSimpleTemplateIdType(
3483 ParamType->getAs<PointerType>()->getPointeeType())))
3484 TDF |= TDF_DerivedClass;
3490 hasDeducibleTemplateParameters(Sema &S, FunctionTemplateDecl *FunctionTemplate,
3493 static Sema::TemplateDeductionResult DeduceTemplateArgumentsFromCallArgument(
3494 Sema &S, TemplateParameterList *TemplateParams, unsigned FirstInnerIndex,
3495 QualType ParamType, Expr *Arg, TemplateDeductionInfo &Info,
3496 SmallVectorImpl<DeducedTemplateArgument> &Deduced,
3497 SmallVectorImpl<Sema::OriginalCallArg> &OriginalCallArgs,
3498 bool DecomposedParam, unsigned ArgIdx, unsigned TDF);
3500 /// \brief Attempt template argument deduction from an initializer list
3501 /// deemed to be an argument in a function call.
3502 static Sema::TemplateDeductionResult DeduceFromInitializerList(
3503 Sema &S, TemplateParameterList *TemplateParams, QualType AdjustedParamType,
3504 InitListExpr *ILE, TemplateDeductionInfo &Info,
3505 SmallVectorImpl<DeducedTemplateArgument> &Deduced,
3506 SmallVectorImpl<Sema::OriginalCallArg> &OriginalCallArgs, unsigned ArgIdx,
3508 // C++ [temp.deduct.call]p1: (CWG 1591)
3509 // If removing references and cv-qualifiers from P gives
3510 // std::initializer_list<P0> or P0[N] for some P0 and N and the argument is
3511 // a non-empty initializer list, then deduction is performed instead for
3512 // each element of the initializer list, taking P0 as a function template
3513 // parameter type and the initializer element as its argument
3515 // We've already removed references and cv-qualifiers here.
3516 if (!ILE->getNumInits())
3517 return Sema::TDK_Success;
3520 auto *ArrTy = S.Context.getAsArrayType(AdjustedParamType);
3522 ElTy = ArrTy->getElementType();
3523 else if (!S.isStdInitializerList(AdjustedParamType, &ElTy)) {
3524 // Otherwise, an initializer list argument causes the parameter to be
3525 // considered a non-deduced context
3526 return Sema::TDK_Success;
3529 // Deduction only needs to be done for dependent types.
3530 if (ElTy->isDependentType()) {
3531 for (Expr *E : ILE->inits()) {
3532 if (auto Result = DeduceTemplateArgumentsFromCallArgument(
3533 S, TemplateParams, 0, ElTy, E, Info, Deduced, OriginalCallArgs, true,
3539 // in the P0[N] case, if N is a non-type template parameter, N is deduced
3540 // from the length of the initializer list.
3541 if (auto *DependentArrTy = dyn_cast_or_null<DependentSizedArrayType>(ArrTy)) {
3542 // Determine the array bound is something we can deduce.
3543 if (NonTypeTemplateParmDecl *NTTP =
3544 getDeducedParameterFromExpr(Info, DependentArrTy->getSizeExpr())) {
3545 // We can perform template argument deduction for the given non-type
3546 // template parameter.
3547 // C++ [temp.deduct.type]p13:
3548 // The type of N in the type T[N] is std::size_t.
3549 QualType T = S.Context.getSizeType();
3550 llvm::APInt Size(S.Context.getIntWidth(T), ILE->getNumInits());
3551 if (auto Result = DeduceNonTypeTemplateArgument(
3552 S, TemplateParams, NTTP, llvm::APSInt(Size), T,
3553 /*ArrayBound=*/true, Info, Deduced))
3558 return Sema::TDK_Success;
3561 /// \brief Perform template argument deduction per [temp.deduct.call] for a
3562 /// single parameter / argument pair.
3563 static Sema::TemplateDeductionResult DeduceTemplateArgumentsFromCallArgument(
3564 Sema &S, TemplateParameterList *TemplateParams, unsigned FirstInnerIndex,
3565 QualType ParamType, Expr *Arg, TemplateDeductionInfo &Info,
3566 SmallVectorImpl<DeducedTemplateArgument> &Deduced,
3567 SmallVectorImpl<Sema::OriginalCallArg> &OriginalCallArgs,
3568 bool DecomposedParam, unsigned ArgIdx, unsigned TDF) {
3569 QualType ArgType = Arg->getType();
3570 QualType OrigParamType = ParamType;
3572 // If P is a reference type [...]
3573 // If P is a cv-qualified type [...]
3574 if (AdjustFunctionParmAndArgTypesForDeduction(
3575 S, TemplateParams, FirstInnerIndex, ParamType, ArgType, Arg, TDF))
3576 return Sema::TDK_Success;
3578 // If [...] the argument is a non-empty initializer list [...]
3579 if (InitListExpr *ILE = dyn_cast<InitListExpr>(Arg))
3580 return DeduceFromInitializerList(S, TemplateParams, ParamType, ILE, Info,
3581 Deduced, OriginalCallArgs, ArgIdx, TDF);
3583 // [...] the deduction process attempts to find template argument values
3584 // that will make the deduced A identical to A
3586 // Keep track of the argument type and corresponding parameter index,
3587 // so we can check for compatibility between the deduced A and A.
3588 OriginalCallArgs.push_back(
3589 Sema::OriginalCallArg(OrigParamType, DecomposedParam, ArgIdx, ArgType));
3590 return DeduceTemplateArgumentsByTypeMatch(S, TemplateParams, ParamType,
3591 ArgType, Info, Deduced, TDF);
3594 /// \brief Perform template argument deduction from a function call
3595 /// (C++ [temp.deduct.call]).
3597 /// \param FunctionTemplate the function template for which we are performing
3598 /// template argument deduction.
3600 /// \param ExplicitTemplateArgs the explicit template arguments provided
3603 /// \param Args the function call arguments
3605 /// \param Specialization if template argument deduction was successful,
3606 /// this will be set to the function template specialization produced by
3607 /// template argument deduction.
3609 /// \param Info the argument will be updated to provide additional information
3610 /// about template argument deduction.
3612 /// \param CheckNonDependent A callback to invoke to check conversions for
3613 /// non-dependent parameters, between deduction and substitution, per DR1391.
3614 /// If this returns true, substitution will be skipped and we return
3615 /// TDK_NonDependentConversionFailure. The callback is passed the parameter
3616 /// types (after substituting explicit template arguments).
3618 /// \returns the result of template argument deduction.
3619 Sema::TemplateDeductionResult Sema::DeduceTemplateArguments(
3620 FunctionTemplateDecl *FunctionTemplate,
3621 TemplateArgumentListInfo *ExplicitTemplateArgs, ArrayRef<Expr *> Args,
3622 FunctionDecl *&Specialization, TemplateDeductionInfo &Info,
3623 bool PartialOverloading,
3624 llvm::function_ref<bool(ArrayRef<QualType>)> CheckNonDependent) {
3625 if (FunctionTemplate->isInvalidDecl())
3628 FunctionDecl *Function = FunctionTemplate->getTemplatedDecl();
3629 unsigned NumParams = Function->getNumParams();
3631 unsigned FirstInnerIndex = getFirstInnerIndex(FunctionTemplate);
3633 // C++ [temp.deduct.call]p1:
3634 // Template argument deduction is done by comparing each function template
3635 // parameter type (call it P) with the type of the corresponding argument
3636 // of the call (call it A) as described below.
3637 if (Args.size() < Function->getMinRequiredArguments() && !PartialOverloading)
3638 return TDK_TooFewArguments;
3639 else if (TooManyArguments(NumParams, Args.size(), PartialOverloading)) {
3640 const FunctionProtoType *Proto
3641 = Function->getType()->getAs<FunctionProtoType>();
3642 if (Proto->isTemplateVariadic())
3644 else if (!Proto->isVariadic())
3645 return TDK_TooManyArguments;
3648 // The types of the parameters from which we will perform template argument
3650 LocalInstantiationScope InstScope(*this);
3651 TemplateParameterList *TemplateParams
3652 = FunctionTemplate->getTemplateParameters();
3653 SmallVector<DeducedTemplateArgument, 4> Deduced;
3654 SmallVector<QualType, 8> ParamTypes;
3655 unsigned NumExplicitlySpecified = 0;
3656 if (ExplicitTemplateArgs) {
3657 TemplateDeductionResult Result =
3658 SubstituteExplicitTemplateArguments(FunctionTemplate,
3659 *ExplicitTemplateArgs,
3667 NumExplicitlySpecified = Deduced.size();
3669 // Just fill in the parameter types from the function declaration.
3670 for (unsigned I = 0; I != NumParams; ++I)
3671 ParamTypes.push_back(Function->getParamDecl(I)->getType());
3674 SmallVector<OriginalCallArg, 8> OriginalCallArgs;
3676 // Deduce an argument of type ParamType from an expression with index ArgIdx.
3677 auto DeduceCallArgument = [&](QualType ParamType, unsigned ArgIdx) {
3678 // C++ [demp.deduct.call]p1: (DR1391)
3679 // Template argument deduction is done by comparing each function template
3680 // parameter that contains template-parameters that participate in
3681 // template argument deduction ...
3682 if (!hasDeducibleTemplateParameters(*this, FunctionTemplate, ParamType))
3683 return Sema::TDK_Success;
3685 // ... with the type of the corresponding argument
3686 return DeduceTemplateArgumentsFromCallArgument(
3687 *this, TemplateParams, FirstInnerIndex, ParamType, Args[ArgIdx], Info, Deduced,
3688 OriginalCallArgs, /*Decomposed*/false, ArgIdx, /*TDF*/ 0);
3691 // Deduce template arguments from the function parameters.
3692 Deduced.resize(TemplateParams->size());
3693 SmallVector<QualType, 8> ParamTypesForArgChecking;
3694 for (unsigned ParamIdx = 0, NumParamTypes = ParamTypes.size(), ArgIdx = 0;
3695 ParamIdx != NumParamTypes; ++ParamIdx) {
3696 QualType ParamType = ParamTypes[ParamIdx];
3698 const PackExpansionType *ParamExpansion =
3699 dyn_cast<PackExpansionType>(ParamType);
3700 if (!ParamExpansion) {
3701 // Simple case: matching a function parameter to a function argument.
3702 if (ArgIdx >= Args.size())
3705 ParamTypesForArgChecking.push_back(ParamType);
3706 if (auto Result = DeduceCallArgument(ParamType, ArgIdx++))
3712 QualType ParamPattern = ParamExpansion->getPattern();
3713 PackDeductionScope PackScope(*this, TemplateParams, Deduced, Info,
3716 // C++0x [temp.deduct.call]p1:
3717 // For a function parameter pack that occurs at the end of the
3718 // parameter-declaration-list, the type A of each remaining argument of
3719 // the call is compared with the type P of the declarator-id of the
3720 // function parameter pack. Each comparison deduces template arguments
3721 // for subsequent positions in the template parameter packs expanded by
3722 // the function parameter pack. When a function parameter pack appears
3723 // in a non-deduced context [not at the end of the list], the type of
3724 // that parameter pack is never deduced.
3726 // FIXME: The above rule allows the size of the parameter pack to change
3727 // after we skip it (in the non-deduced case). That makes no sense, so
3728 // we instead notionally deduce the pack against N arguments, where N is
3729 // the length of the explicitly-specified pack if it's expanded by the
3730 // parameter pack and 0 otherwise, and we treat each deduction as a
3731 // non-deduced context.
3732 if (ParamIdx + 1 == NumParamTypes) {
3733 for (; ArgIdx < Args.size(); PackScope.nextPackElement(), ++ArgIdx) {
3734 ParamTypesForArgChecking.push_back(ParamPattern);
3735 if (auto Result = DeduceCallArgument(ParamPattern, ArgIdx))
3739 // If the parameter type contains an explicitly-specified pack that we
3740 // could not expand, skip the number of parameters notionally created
3741 // by the expansion.
3742 Optional<unsigned> NumExpansions = ParamExpansion->getNumExpansions();
3743 if (NumExpansions && !PackScope.isPartiallyExpanded()) {
3744 for (unsigned I = 0; I != *NumExpansions && ArgIdx < Args.size();
3746 ParamTypesForArgChecking.push_back(ParamPattern);
3747 // FIXME: Should we add OriginalCallArgs for these? What if the
3748 // corresponding argument is a list?
3749 PackScope.nextPackElement();
3754 // Build argument packs for each of the parameter packs expanded by this
3756 if (auto Result = PackScope.finish())
3760 return FinishTemplateArgumentDeduction(
3761 FunctionTemplate, Deduced, NumExplicitlySpecified, Specialization, Info,
3762 &OriginalCallArgs, PartialOverloading,
3763 [&]() { return CheckNonDependent(ParamTypesForArgChecking); });
3766 QualType Sema::adjustCCAndNoReturn(QualType ArgFunctionType,
3767 QualType FunctionType,
3768 bool AdjustExceptionSpec) {
3769 if (ArgFunctionType.isNull())
3770 return ArgFunctionType;
3772 const FunctionProtoType *FunctionTypeP =
3773 FunctionType->castAs<FunctionProtoType>();
3774 const FunctionProtoType *ArgFunctionTypeP =
3775 ArgFunctionType->getAs<FunctionProtoType>();
3777 FunctionProtoType::ExtProtoInfo EPI = ArgFunctionTypeP->getExtProtoInfo();
3778 bool Rebuild = false;
3780 CallingConv CC = FunctionTypeP->getCallConv();
3781 if (EPI.ExtInfo.getCC() != CC) {
3782 EPI.ExtInfo = EPI.ExtInfo.withCallingConv(CC);
3786 bool NoReturn = FunctionTypeP->getNoReturnAttr();
3787 if (EPI.ExtInfo.getNoReturn() != NoReturn) {
3788 EPI.ExtInfo = EPI.ExtInfo.withNoReturn(NoReturn);
3792 if (AdjustExceptionSpec && (FunctionTypeP->hasExceptionSpec() ||
3793 ArgFunctionTypeP->hasExceptionSpec())) {
3794 EPI.ExceptionSpec = FunctionTypeP->getExtProtoInfo().ExceptionSpec;
3799 return ArgFunctionType;
3801 return Context.getFunctionType(ArgFunctionTypeP->getReturnType(),
3802 ArgFunctionTypeP->getParamTypes(), EPI);
3805 /// \brief Deduce template arguments when taking the address of a function
3806 /// template (C++ [temp.deduct.funcaddr]) or matching a specialization to
3809 /// \param FunctionTemplate the function template for which we are performing
3810 /// template argument deduction.
3812 /// \param ExplicitTemplateArgs the explicitly-specified template
3815 /// \param ArgFunctionType the function type that will be used as the
3816 /// "argument" type (A) when performing template argument deduction from the
3817 /// function template's function type. This type may be NULL, if there is no
3818 /// argument type to compare against, in C++0x [temp.arg.explicit]p3.
3820 /// \param Specialization if template argument deduction was successful,
3821 /// this will be set to the function template specialization produced by
3822 /// template argument deduction.
3824 /// \param Info the argument will be updated to provide additional information
3825 /// about template argument deduction.
3827 /// \param IsAddressOfFunction If \c true, we are deducing as part of taking
3828 /// the address of a function template per [temp.deduct.funcaddr] and
3829 /// [over.over]. If \c false, we are looking up a function template
3830 /// specialization based on its signature, per [temp.deduct.decl].
3832 /// \returns the result of template argument deduction.
3833 Sema::TemplateDeductionResult Sema::DeduceTemplateArguments(
3834 FunctionTemplateDecl *FunctionTemplate,
3835 TemplateArgumentListInfo *ExplicitTemplateArgs, QualType ArgFunctionType,
3836 FunctionDecl *&Specialization, TemplateDeductionInfo &Info,
3837 bool IsAddressOfFunction) {
3838 if (FunctionTemplate->isInvalidDecl())
3841 FunctionDecl *Function = FunctionTemplate->getTemplatedDecl();
3842 TemplateParameterList *TemplateParams
3843 = FunctionTemplate->getTemplateParameters();
3844 QualType FunctionType = Function->getType();
3846 // Substitute any explicit template arguments.
3847 LocalInstantiationScope InstScope(*this);
3848 SmallVector<DeducedTemplateArgument, 4> Deduced;
3849 unsigned NumExplicitlySpecified = 0;
3850 SmallVector<QualType, 4> ParamTypes;
3851 if (ExplicitTemplateArgs) {
3852 if (TemplateDeductionResult Result
3853 = SubstituteExplicitTemplateArguments(FunctionTemplate,
3854 *ExplicitTemplateArgs,
3855 Deduced, ParamTypes,
3856 &FunctionType, Info))
3859 NumExplicitlySpecified = Deduced.size();
3862 // When taking the address of a function, we require convertibility of
3863 // the resulting function type. Otherwise, we allow arbitrary mismatches
3864 // of calling convention and noreturn.
3865 if (!IsAddressOfFunction)
3866 ArgFunctionType = adjustCCAndNoReturn(ArgFunctionType, FunctionType,
3867 /*AdjustExceptionSpec*/false);
3869 // Unevaluated SFINAE context.
3870 EnterExpressionEvaluationContext Unevaluated(
3871 *this, Sema::ExpressionEvaluationContext::Unevaluated);
3872 SFINAETrap Trap(*this);
3874 Deduced.resize(TemplateParams->size());
3876 // If the function has a deduced return type, substitute it for a dependent
3877 // type so that we treat it as a non-deduced context in what follows. If we
3878 // are looking up by signature, the signature type should also have a deduced
3879 // return type, which we instead expect to exactly match.
3880 bool HasDeducedReturnType = false;
3881 if (getLangOpts().CPlusPlus14 && IsAddressOfFunction &&
3882 Function->getReturnType()->getContainedAutoType()) {
3883 FunctionType = SubstAutoType(FunctionType, Context.DependentTy);
3884 HasDeducedReturnType = true;
3887 if (!ArgFunctionType.isNull()) {
3889 TDF_TopLevelParameterTypeList | TDF_AllowCompatibleFunctionType;
3890 // Deduce template arguments from the function type.
3891 if (TemplateDeductionResult Result
3892 = DeduceTemplateArgumentsByTypeMatch(*this, TemplateParams,
3893 FunctionType, ArgFunctionType,
3894 Info, Deduced, TDF))
3898 if (TemplateDeductionResult Result
3899 = FinishTemplateArgumentDeduction(FunctionTemplate, Deduced,
3900 NumExplicitlySpecified,
3901 Specialization, Info))
3904 // If the function has a deduced return type, deduce it now, so we can check
3905 // that the deduced function type matches the requested type.
3906 if (HasDeducedReturnType &&
3907 Specialization->getReturnType()->isUndeducedType() &&
3908 DeduceReturnType(Specialization, Info.getLocation(), false))
3909 return TDK_MiscellaneousDeductionFailure;
3911 // If the function has a dependent exception specification, resolve it now,
3912 // so we can check that the exception specification matches.
3913 auto *SpecializationFPT =
3914 Specialization->getType()->castAs<FunctionProtoType>();
3915 if (getLangOpts().CPlusPlus17 &&
3916 isUnresolvedExceptionSpec(SpecializationFPT->getExceptionSpecType()) &&
3917 !ResolveExceptionSpec(Info.getLocation(), SpecializationFPT))
3918 return TDK_MiscellaneousDeductionFailure;
3920 // Adjust the exception specification of the argument to match the
3921 // substituted and resolved type we just formed. (Calling convention and
3922 // noreturn can't be dependent, so we don't actually need this for them
3924 QualType SpecializationType = Specialization->getType();
3925 if (!IsAddressOfFunction)
3926 ArgFunctionType = adjustCCAndNoReturn(ArgFunctionType, SpecializationType,
3927 /*AdjustExceptionSpec*/true);
3929 // If the requested function type does not match the actual type of the
3930 // specialization with respect to arguments of compatible pointer to function
3931 // types, template argument deduction fails.
3932 if (!ArgFunctionType.isNull()) {
3933 if (IsAddressOfFunction &&
3934 !isSameOrCompatibleFunctionType(
3935 Context.getCanonicalType(SpecializationType),
3936 Context.getCanonicalType(ArgFunctionType)))
3937 return TDK_MiscellaneousDeductionFailure;
3939 if (!IsAddressOfFunction &&
3940 !Context.hasSameType(SpecializationType, ArgFunctionType))
3941 return TDK_MiscellaneousDeductionFailure;
3947 /// \brief Deduce template arguments for a templated conversion
3948 /// function (C++ [temp.deduct.conv]) and, if successful, produce a
3949 /// conversion function template specialization.
3950 Sema::TemplateDeductionResult
3951 Sema::DeduceTemplateArguments(FunctionTemplateDecl *ConversionTemplate,
3953 CXXConversionDecl *&Specialization,
3954 TemplateDeductionInfo &Info) {
3955 if (ConversionTemplate->isInvalidDecl())
3958 CXXConversionDecl *ConversionGeneric
3959 = cast<CXXConversionDecl>(ConversionTemplate->getTemplatedDecl());
3961 QualType FromType = ConversionGeneric->getConversionType();
3963 // Canonicalize the types for deduction.
3964 QualType P = Context.getCanonicalType(FromType);
3965 QualType A = Context.getCanonicalType(ToType);
3967 // C++0x [temp.deduct.conv]p2:
3968 // If P is a reference type, the type referred to by P is used for
3970 if (const ReferenceType *PRef = P->getAs<ReferenceType>())
3971 P = PRef->getPointeeType();
3973 // C++0x [temp.deduct.conv]p4:
3974 // [...] If A is a reference type, the type referred to by A is used
3975 // for type deduction.
3976 if (const ReferenceType *ARef = A->getAs<ReferenceType>())
3977 A = ARef->getPointeeType().getUnqualifiedType();
3978 // C++ [temp.deduct.conv]p3:
3980 // If A is not a reference type:
3982 assert(!A->isReferenceType() && "Reference types were handled above");
3984 // - If P is an array type, the pointer type produced by the
3985 // array-to-pointer standard conversion (4.2) is used in place
3986 // of P for type deduction; otherwise,
3987 if (P->isArrayType())
3988 P = Context.getArrayDecayedType(P);
3989 // - If P is a function type, the pointer type produced by the
3990 // function-to-pointer standard conversion (4.3) is used in
3991 // place of P for type deduction; otherwise,
3992 else if (P->isFunctionType())
3993 P = Context.getPointerType(P);
3994 // - If P is a cv-qualified type, the top level cv-qualifiers of
3995 // P's type are ignored for type deduction.
3997 P = P.getUnqualifiedType();
3999 // C++0x [temp.deduct.conv]p4:
4000 // If A is a cv-qualified type, the top level cv-qualifiers of A's
4001 // type are ignored for type deduction. If A is a reference type, the type
4002 // referred to by A is used for type deduction.
4003 A = A.getUnqualifiedType();
4006 // Unevaluated SFINAE context.
4007 EnterExpressionEvaluationContext Unevaluated(
4008 *this, Sema::ExpressionEvaluationContext::Unevaluated);
4009 SFINAETrap Trap(*this);
4011 // C++ [temp.deduct.conv]p1:
4012 // Template argument deduction is done by comparing the return
4013 // type of the template conversion function (call it P) with the
4014 // type that is required as the result of the conversion (call it
4015 // A) as described in 14.8.2.4.
4016 TemplateParameterList *TemplateParams
4017 = ConversionTemplate->getTemplateParameters();
4018 SmallVector<DeducedTemplateArgument, 4> Deduced;
4019 Deduced.resize(TemplateParams->size());
4021 // C++0x [temp.deduct.conv]p4:
4022 // In general, the deduction process attempts to find template
4023 // argument values that will make the deduced A identical to
4024 // A. However, there are two cases that allow a difference:
4026 // - If the original A is a reference type, A can be more
4027 // cv-qualified than the deduced A (i.e., the type referred to
4028 // by the reference)
4029 if (ToType->isReferenceType())
4030 TDF |= TDF_ParamWithReferenceType;
4031 // - The deduced A can be another pointer or pointer to member
4032 // type that can be converted to A via a qualification
4035 // (C++0x [temp.deduct.conv]p6 clarifies that this only happens when
4036 // both P and A are pointers or member pointers. In this case, we
4037 // just ignore cv-qualifiers completely).
4038 if ((P->isPointerType() && A->isPointerType()) ||
4039 (P->isMemberPointerType() && A->isMemberPointerType()))
4040 TDF |= TDF_IgnoreQualifiers;
4041 if (TemplateDeductionResult Result
4042 = DeduceTemplateArgumentsByTypeMatch(*this, TemplateParams,
4043 P, A, Info, Deduced, TDF))
4046 // Create an Instantiation Scope for finalizing the operator.
4047 LocalInstantiationScope InstScope(*this);
4048 // Finish template argument deduction.
4049 FunctionDecl *ConversionSpecialized = nullptr;
4050 TemplateDeductionResult Result
4051 = FinishTemplateArgumentDeduction(ConversionTemplate, Deduced, 0,
4052 ConversionSpecialized, Info);
4053 Specialization = cast_or_null<CXXConversionDecl>(ConversionSpecialized);
4057 /// \brief Deduce template arguments for a function template when there is
4058 /// nothing to deduce against (C++0x [temp.arg.explicit]p3).
4060 /// \param FunctionTemplate the function template for which we are performing
4061 /// template argument deduction.
4063 /// \param ExplicitTemplateArgs the explicitly-specified template
4066 /// \param Specialization if template argument deduction was successful,
4067 /// this will be set to the function template specialization produced by
4068 /// template argument deduction.
4070 /// \param Info the argument will be updated to provide additional information
4071 /// about template argument deduction.
4073 /// \param IsAddressOfFunction If \c true, we are deducing as part of taking
4074 /// the address of a function template in a context where we do not have a
4075 /// target type, per [over.over]. If \c false, we are looking up a function
4076 /// template specialization based on its signature, which only happens when
4077 /// deducing a function parameter type from an argument that is a template-id
4078 /// naming a function template specialization.
4080 /// \returns the result of template argument deduction.
4081 Sema::TemplateDeductionResult Sema::DeduceTemplateArguments(
4082 FunctionTemplateDecl *FunctionTemplate,
4083 TemplateArgumentListInfo *ExplicitTemplateArgs,
4084 FunctionDecl *&Specialization, TemplateDeductionInfo &Info,
4085 bool IsAddressOfFunction) {
4086 return DeduceTemplateArguments(FunctionTemplate, ExplicitTemplateArgs,
4087 QualType(), Specialization, Info,
4088 IsAddressOfFunction);
4092 /// Substitute the 'auto' specifier or deduced template specialization type
4093 /// specifier within a type for a given replacement type.
4094 class SubstituteDeducedTypeTransform :
4095 public TreeTransform<SubstituteDeducedTypeTransform> {
4096 QualType Replacement;
4099 SubstituteDeducedTypeTransform(Sema &SemaRef, QualType Replacement,
4100 bool UseTypeSugar = true)
4101 : TreeTransform<SubstituteDeducedTypeTransform>(SemaRef),
4102 Replacement(Replacement), UseTypeSugar(UseTypeSugar) {}
4104 QualType TransformDesugared(TypeLocBuilder &TLB, DeducedTypeLoc TL) {
4105 assert(isa<TemplateTypeParmType>(Replacement) &&
4106 "unexpected unsugared replacement kind");
4107 QualType Result = Replacement;
4108 TemplateTypeParmTypeLoc NewTL = TLB.push<TemplateTypeParmTypeLoc>(Result);
4109 NewTL.setNameLoc(TL.getNameLoc());
4113 QualType TransformAutoType(TypeLocBuilder &TLB, AutoTypeLoc TL) {
4114 // If we're building the type pattern to deduce against, don't wrap the
4115 // substituted type in an AutoType. Certain template deduction rules
4116 // apply only when a template type parameter appears directly (and not if
4117 // the parameter is found through desugaring). For instance:
4118 // auto &&lref = lvalue;
4119 // must transform into "rvalue reference to T" not "rvalue reference to
4120 // auto type deduced as T" in order for [temp.deduct.call]p3 to apply.
4122 // FIXME: Is this still necessary?
4124 return TransformDesugared(TLB, TL);
4126 QualType Result = SemaRef.Context.getAutoType(
4127 Replacement, TL.getTypePtr()->getKeyword(), Replacement.isNull());
4128 auto NewTL = TLB.push<AutoTypeLoc>(Result);
4129 NewTL.setNameLoc(TL.getNameLoc());
4133 QualType TransformDeducedTemplateSpecializationType(
4134 TypeLocBuilder &TLB, DeducedTemplateSpecializationTypeLoc TL) {
4136 return TransformDesugared(TLB, TL);
4138 QualType Result = SemaRef.Context.getDeducedTemplateSpecializationType(
4139 TL.getTypePtr()->getTemplateName(),
4140 Replacement, Replacement.isNull());
4141 auto NewTL = TLB.push<DeducedTemplateSpecializationTypeLoc>(Result);
4142 NewTL.setNameLoc(TL.getNameLoc());
4146 ExprResult TransformLambdaExpr(LambdaExpr *E) {
4147 // Lambdas never need to be transformed.
4151 QualType Apply(TypeLoc TL) {
4152 // Create some scratch storage for the transformed type locations.
4153 // FIXME: We're just going to throw this information away. Don't build it.
4155 TLB.reserve(TL.getFullDataSize());
4156 return TransformType(TLB, TL);
4161 Sema::DeduceAutoResult
4162 Sema::DeduceAutoType(TypeSourceInfo *Type, Expr *&Init, QualType &Result,
4163 Optional<unsigned> DependentDeductionDepth) {
4164 return DeduceAutoType(Type->getTypeLoc(), Init, Result,
4165 DependentDeductionDepth);
4168 /// Attempt to produce an informative diagostic explaining why auto deduction
4170 /// \return \c true if diagnosed, \c false if not.
4171 static bool diagnoseAutoDeductionFailure(Sema &S,
4172 Sema::TemplateDeductionResult TDK,
4173 TemplateDeductionInfo &Info,
4174 ArrayRef<SourceRange> Ranges) {
4176 case Sema::TDK_Inconsistent: {
4177 // Inconsistent deduction means we were deducing from an initializer list.
4178 auto D = S.Diag(Info.getLocation(), diag::err_auto_inconsistent_deduction);
4179 D << Info.FirstArg << Info.SecondArg;
4180 for (auto R : Ranges)
4185 // FIXME: Are there other cases for which a custom diagnostic is more useful
4186 // than the basic "types don't match" diagnostic?
4193 /// \brief Deduce the type for an auto type-specifier (C++11 [dcl.spec.auto]p6)
4195 /// Note that this is done even if the initializer is dependent. (This is
4196 /// necessary to support partial ordering of templates using 'auto'.)
4197 /// A dependent type will be produced when deducing from a dependent type.
4199 /// \param Type the type pattern using the auto type-specifier.
4200 /// \param Init the initializer for the variable whose type is to be deduced.
4201 /// \param Result if type deduction was successful, this will be set to the
4203 /// \param DependentDeductionDepth Set if we should permit deduction in
4204 /// dependent cases. This is necessary for template partial ordering with
4205 /// 'auto' template parameters. The value specified is the template
4206 /// parameter depth at which we should perform 'auto' deduction.
4207 Sema::DeduceAutoResult
4208 Sema::DeduceAutoType(TypeLoc Type, Expr *&Init, QualType &Result,
4209 Optional<unsigned> DependentDeductionDepth) {
4210 if (Init->getType()->isNonOverloadPlaceholderType()) {
4211 ExprResult NonPlaceholder = CheckPlaceholderExpr(Init);
4212 if (NonPlaceholder.isInvalid())
4213 return DAR_FailedAlreadyDiagnosed;
4214 Init = NonPlaceholder.get();
4217 if (!DependentDeductionDepth &&
4218 (Type.getType()->isDependentType() || Init->isTypeDependent())) {
4219 Result = SubstituteDeducedTypeTransform(*this, QualType()).Apply(Type);
4220 assert(!Result.isNull() && "substituting DependentTy can't fail");
4221 return DAR_Succeeded;
4224 // Find the depth of template parameter to synthesize.
4225 unsigned Depth = DependentDeductionDepth.getValueOr(0);
4227 // If this is a 'decltype(auto)' specifier, do the decltype dance.
4228 // Since 'decltype(auto)' can only occur at the top of the type, we
4229 // don't need to go digging for it.
4230 if (const AutoType *AT = Type.getType()->getAs<AutoType>()) {
4231 if (AT->isDecltypeAuto()) {
4232 if (isa<InitListExpr>(Init)) {
4233 Diag(Init->getLocStart(), diag::err_decltype_auto_initializer_list);
4234 return DAR_FailedAlreadyDiagnosed;
4237 QualType Deduced = BuildDecltypeType(Init, Init->getLocStart(), false);
4238 if (Deduced.isNull())
4239 return DAR_FailedAlreadyDiagnosed;
4240 // FIXME: Support a non-canonical deduced type for 'auto'.
4241 Deduced = Context.getCanonicalType(Deduced);
4242 Result = SubstituteDeducedTypeTransform(*this, Deduced).Apply(Type);
4243 if (Result.isNull())
4244 return DAR_FailedAlreadyDiagnosed;
4245 return DAR_Succeeded;
4246 } else if (!getLangOpts().CPlusPlus) {
4247 if (isa<InitListExpr>(Init)) {
4248 Diag(Init->getLocStart(), diag::err_auto_init_list_from_c);
4249 return DAR_FailedAlreadyDiagnosed;
4254 SourceLocation Loc = Init->getExprLoc();
4256 LocalInstantiationScope InstScope(*this);
4258 // Build template<class TemplParam> void Func(FuncParam);
4259 TemplateTypeParmDecl *TemplParam = TemplateTypeParmDecl::Create(
4260 Context, nullptr, SourceLocation(), Loc, Depth, 0, nullptr, false, false);
4261 QualType TemplArg = QualType(TemplParam->getTypeForDecl(), 0);
4262 NamedDecl *TemplParamPtr = TemplParam;
4263 FixedSizeTemplateParameterListStorage<1, false> TemplateParamsSt(
4264 Loc, Loc, TemplParamPtr, Loc, nullptr);
4266 QualType FuncParam =
4267 SubstituteDeducedTypeTransform(*this, TemplArg, /*UseTypeSugar*/false)
4269 assert(!FuncParam.isNull() &&
4270 "substituting template parameter for 'auto' failed");
4272 // Deduce type of TemplParam in Func(Init)
4273 SmallVector<DeducedTemplateArgument, 1> Deduced;
4276 TemplateDeductionInfo Info(Loc, Depth);
4278 // If deduction failed, don't diagnose if the initializer is dependent; it
4279 // might acquire a matching type in the instantiation.
4280 auto DeductionFailed = [&](TemplateDeductionResult TDK,
4281 ArrayRef<SourceRange> Ranges) -> DeduceAutoResult {
4282 if (Init->isTypeDependent()) {
4283 Result = SubstituteDeducedTypeTransform(*this, QualType()).Apply(Type);
4284 assert(!Result.isNull() && "substituting DependentTy can't fail");
4285 return DAR_Succeeded;
4287 if (diagnoseAutoDeductionFailure(*this, TDK, Info, Ranges))
4288 return DAR_FailedAlreadyDiagnosed;
4292 SmallVector<OriginalCallArg, 4> OriginalCallArgs;
4294 InitListExpr *InitList = dyn_cast<InitListExpr>(Init);
4296 // Notionally, we substitute std::initializer_list<T> for 'auto' and deduce
4297 // against that. Such deduction only succeeds if removing cv-qualifiers and
4298 // references results in std::initializer_list<T>.
4299 if (!Type.getType().getNonReferenceType()->getAs<AutoType>())
4302 SourceRange DeducedFromInitRange;
4303 for (unsigned i = 0, e = InitList->getNumInits(); i < e; ++i) {
4304 Expr *Init = InitList->getInit(i);
4306 if (auto TDK = DeduceTemplateArgumentsFromCallArgument(
4307 *this, TemplateParamsSt.get(), 0, TemplArg, Init,
4308 Info, Deduced, OriginalCallArgs, /*Decomposed*/ true,
4309 /*ArgIdx*/ 0, /*TDF*/ 0))
4310 return DeductionFailed(TDK, {DeducedFromInitRange,
4311 Init->getSourceRange()});
4313 if (DeducedFromInitRange.isInvalid() &&
4314 Deduced[0].getKind() != TemplateArgument::Null)
4315 DeducedFromInitRange = Init->getSourceRange();
4318 if (!getLangOpts().CPlusPlus && Init->refersToBitField()) {
4319 Diag(Loc, diag::err_auto_bitfield);
4320 return DAR_FailedAlreadyDiagnosed;
4323 if (auto TDK = DeduceTemplateArgumentsFromCallArgument(
4324 *this, TemplateParamsSt.get(), 0, FuncParam, Init, Info, Deduced,
4325 OriginalCallArgs, /*Decomposed*/ false, /*ArgIdx*/ 0, /*TDF*/ 0))
4326 return DeductionFailed(TDK, {});
4329 // Could be null if somehow 'auto' appears in a non-deduced context.
4330 if (Deduced[0].getKind() != TemplateArgument::Type)
4331 return DeductionFailed(TDK_Incomplete, {});
4333 QualType DeducedType = Deduced[0].getAsType();
4336 DeducedType = BuildStdInitializerList(DeducedType, Loc);
4337 if (DeducedType.isNull())
4338 return DAR_FailedAlreadyDiagnosed;
4341 Result = SubstituteDeducedTypeTransform(*this, DeducedType).Apply(Type);
4342 if (Result.isNull())
4343 return DAR_FailedAlreadyDiagnosed;
4345 // Check that the deduced argument type is compatible with the original
4346 // argument type per C++ [temp.deduct.call]p4.
4347 QualType DeducedA = InitList ? Deduced[0].getAsType() : Result;
4348 for (const OriginalCallArg &OriginalArg : OriginalCallArgs) {
4349 assert((bool)InitList == OriginalArg.DecomposedParam &&
4350 "decomposed non-init-list in auto deduction?");
4352 CheckOriginalCallArgDeduction(*this, Info, OriginalArg, DeducedA)) {
4353 Result = QualType();
4354 return DeductionFailed(TDK, {});
4358 return DAR_Succeeded;
4361 QualType Sema::SubstAutoType(QualType TypeWithAuto,
4362 QualType TypeToReplaceAuto) {
4363 if (TypeToReplaceAuto->isDependentType())
4364 TypeToReplaceAuto = QualType();
4365 return SubstituteDeducedTypeTransform(*this, TypeToReplaceAuto)
4366 .TransformType(TypeWithAuto);
4369 TypeSourceInfo *Sema::SubstAutoTypeSourceInfo(TypeSourceInfo *TypeWithAuto,
4370 QualType TypeToReplaceAuto) {
4371 if (TypeToReplaceAuto->isDependentType())
4372 TypeToReplaceAuto = QualType();
4373 return SubstituteDeducedTypeTransform(*this, TypeToReplaceAuto)
4374 .TransformType(TypeWithAuto);
4377 QualType Sema::ReplaceAutoType(QualType TypeWithAuto,
4378 QualType TypeToReplaceAuto) {
4379 return SubstituteDeducedTypeTransform(*this, TypeToReplaceAuto,
4380 /*UseTypeSugar*/ false)
4381 .TransformType(TypeWithAuto);
4384 void Sema::DiagnoseAutoDeductionFailure(VarDecl *VDecl, Expr *Init) {
4385 if (isa<InitListExpr>(Init))
4386 Diag(VDecl->getLocation(),
4387 VDecl->isInitCapture()
4388 ? diag::err_init_capture_deduction_failure_from_init_list
4389 : diag::err_auto_var_deduction_failure_from_init_list)
4390 << VDecl->getDeclName() << VDecl->getType() << Init->getSourceRange();
4392 Diag(VDecl->getLocation(),
4393 VDecl->isInitCapture() ? diag::err_init_capture_deduction_failure
4394 : diag::err_auto_var_deduction_failure)
4395 << VDecl->getDeclName() << VDecl->getType() << Init->getType()
4396 << Init->getSourceRange();
4399 bool Sema::DeduceReturnType(FunctionDecl *FD, SourceLocation Loc,
4401 assert(FD->getReturnType()->isUndeducedType());
4403 // For a lambda's conversion operator, deduce any 'auto' or 'decltype(auto)'
4404 // within the return type from the call operator's type.
4405 if (isLambdaConversionOperator(FD)) {
4406 CXXRecordDecl *Lambda = cast<CXXMethodDecl>(FD)->getParent();
4407 FunctionDecl *CallOp = Lambda->getLambdaCallOperator();
4409 // For a generic lambda, instantiate the call operator if needed.
4410 if (auto *Args = FD->getTemplateSpecializationArgs()) {
4411 CallOp = InstantiateFunctionDeclaration(
4412 CallOp->getDescribedFunctionTemplate(), Args, Loc);
4413 if (!CallOp || CallOp->isInvalidDecl())
4416 // We might need to deduce the return type by instantiating the definition
4417 // of the operator() function.
4418 if (CallOp->getReturnType()->isUndeducedType())
4419 InstantiateFunctionDefinition(Loc, CallOp);
4422 if (CallOp->isInvalidDecl())
4424 assert(!CallOp->getReturnType()->isUndeducedType() &&
4425 "failed to deduce lambda return type");
4427 // Build the new return type from scratch.
4428 QualType RetType = getLambdaConversionFunctionResultType(
4429 CallOp->getType()->castAs<FunctionProtoType>());
4430 if (FD->getReturnType()->getAs<PointerType>())
4431 RetType = Context.getPointerType(RetType);
4433 assert(FD->getReturnType()->getAs<BlockPointerType>());
4434 RetType = Context.getBlockPointerType(RetType);
4436 Context.adjustDeducedFunctionResultType(FD, RetType);
4440 if (FD->getTemplateInstantiationPattern())
4441 InstantiateFunctionDefinition(Loc, FD);
4443 bool StillUndeduced = FD->getReturnType()->isUndeducedType();
4444 if (StillUndeduced && Diagnose && !FD->isInvalidDecl()) {
4445 Diag(Loc, diag::err_auto_fn_used_before_defined) << FD;
4446 Diag(FD->getLocation(), diag::note_callee_decl) << FD;
4449 return StillUndeduced;
4452 /// \brief If this is a non-static member function,
4454 AddImplicitObjectParameterType(ASTContext &Context,
4455 CXXMethodDecl *Method,
4456 SmallVectorImpl<QualType> &ArgTypes) {
4457 // C++11 [temp.func.order]p3:
4458 // [...] The new parameter is of type "reference to cv A," where cv are
4459 // the cv-qualifiers of the function template (if any) and A is
4460 // the class of which the function template is a member.
4462 // The standard doesn't say explicitly, but we pick the appropriate kind of
4463 // reference type based on [over.match.funcs]p4.
4464 QualType ArgTy = Context.getTypeDeclType(Method->getParent());
4465 ArgTy = Context.getQualifiedType(ArgTy,
4466 Qualifiers::fromCVRMask(Method->getTypeQualifiers()));
4467 if (Method->getRefQualifier() == RQ_RValue)
4468 ArgTy = Context.getRValueReferenceType(ArgTy);
4470 ArgTy = Context.getLValueReferenceType(ArgTy);
4471 ArgTypes.push_back(ArgTy);
4474 /// \brief Determine whether the function template \p FT1 is at least as
4475 /// specialized as \p FT2.
4476 static bool isAtLeastAsSpecializedAs(Sema &S,
4478 FunctionTemplateDecl *FT1,
4479 FunctionTemplateDecl *FT2,
4480 TemplatePartialOrderingContext TPOC,
4481 unsigned NumCallArguments1) {
4482 FunctionDecl *FD1 = FT1->getTemplatedDecl();
4483 FunctionDecl *FD2 = FT2->getTemplatedDecl();
4484 const FunctionProtoType *Proto1 = FD1->getType()->getAs<FunctionProtoType>();
4485 const FunctionProtoType *Proto2 = FD2->getType()->getAs<FunctionProtoType>();
4487 assert(Proto1 && Proto2 && "Function templates must have prototypes");
4488 TemplateParameterList *TemplateParams = FT2->getTemplateParameters();
4489 SmallVector<DeducedTemplateArgument, 4> Deduced;
4490 Deduced.resize(TemplateParams->size());
4492 // C++0x [temp.deduct.partial]p3:
4493 // The types used to determine the ordering depend on the context in which
4494 // the partial ordering is done:
4495 TemplateDeductionInfo Info(Loc);
4496 SmallVector<QualType, 4> Args2;
4499 // - In the context of a function call, the function parameter types are
4501 CXXMethodDecl *Method1 = dyn_cast<CXXMethodDecl>(FD1);
4502 CXXMethodDecl *Method2 = dyn_cast<CXXMethodDecl>(FD2);
4504 // C++11 [temp.func.order]p3:
4505 // [...] If only one of the function templates is a non-static
4506 // member, that function template is considered to have a new
4507 // first parameter inserted in its function parameter list. The
4508 // new parameter is of type "reference to cv A," where cv are
4509 // the cv-qualifiers of the function template (if any) and A is
4510 // the class of which the function template is a member.
4512 // Note that we interpret this to mean "if one of the function
4513 // templates is a non-static member and the other is a non-member";
4514 // otherwise, the ordering rules for static functions against non-static
4515 // functions don't make any sense.
4517 // C++98/03 doesn't have this provision but we've extended DR532 to cover
4518 // it as wording was broken prior to it.
4519 SmallVector<QualType, 4> Args1;
4521 unsigned NumComparedArguments = NumCallArguments1;
4523 if (!Method2 && Method1 && !Method1->isStatic()) {
4524 // Compare 'this' from Method1 against first parameter from Method2.
4525 AddImplicitObjectParameterType(S.Context, Method1, Args1);
4526 ++NumComparedArguments;
4527 } else if (!Method1 && Method2 && !Method2->isStatic()) {
4528 // Compare 'this' from Method2 against first parameter from Method1.
4529 AddImplicitObjectParameterType(S.Context, Method2, Args2);
4532 Args1.insert(Args1.end(), Proto1->param_type_begin(),
4533 Proto1->param_type_end());
4534 Args2.insert(Args2.end(), Proto2->param_type_begin(),
4535 Proto2->param_type_end());
4537 // C++ [temp.func.order]p5:
4538 // The presence of unused ellipsis and default arguments has no effect on
4539 // the partial ordering of function templates.
4540 if (Args1.size() > NumComparedArguments)
4541 Args1.resize(NumComparedArguments);
4542 if (Args2.size() > NumComparedArguments)
4543 Args2.resize(NumComparedArguments);
4544 if (DeduceTemplateArguments(S, TemplateParams, Args2.data(), Args2.size(),
4545 Args1.data(), Args1.size(), Info, Deduced,
4546 TDF_None, /*PartialOrdering=*/true))
4552 case TPOC_Conversion:
4553 // - In the context of a call to a conversion operator, the return types
4554 // of the conversion function templates are used.
4555 if (DeduceTemplateArgumentsByTypeMatch(
4556 S, TemplateParams, Proto2->getReturnType(), Proto1->getReturnType(),
4557 Info, Deduced, TDF_None,
4558 /*PartialOrdering=*/true))
4563 // - In other contexts (14.6.6.2) the function template's function type
4565 if (DeduceTemplateArgumentsByTypeMatch(S, TemplateParams,
4566 FD2->getType(), FD1->getType(),
4567 Info, Deduced, TDF_None,
4568 /*PartialOrdering=*/true))
4573 // C++0x [temp.deduct.partial]p11:
4574 // In most cases, all template parameters must have values in order for
4575 // deduction to succeed, but for partial ordering purposes a template
4576 // parameter may remain without a value provided it is not used in the
4577 // types being used for partial ordering. [ Note: a template parameter used
4578 // in a non-deduced context is considered used. -end note]
4579 unsigned ArgIdx = 0, NumArgs = Deduced.size();
4580 for (; ArgIdx != NumArgs; ++ArgIdx)
4581 if (Deduced[ArgIdx].isNull())
4584 // FIXME: We fail to implement [temp.deduct.type]p1 along this path. We need
4585 // to substitute the deduced arguments back into the template and check that
4586 // we get the right type.
4588 if (ArgIdx == NumArgs) {
4589 // All template arguments were deduced. FT1 is at least as specialized
4594 // Figure out which template parameters were used.
4595 llvm::SmallBitVector UsedParameters(TemplateParams->size());
4598 for (unsigned I = 0, N = Args2.size(); I != N; ++I)
4599 ::MarkUsedTemplateParameters(S.Context, Args2[I], false,
4600 TemplateParams->getDepth(),
4604 case TPOC_Conversion:
4605 ::MarkUsedTemplateParameters(S.Context, Proto2->getReturnType(), false,
4606 TemplateParams->getDepth(), UsedParameters);
4610 ::MarkUsedTemplateParameters(S.Context, FD2->getType(), false,
4611 TemplateParams->getDepth(),
4616 for (; ArgIdx != NumArgs; ++ArgIdx)
4617 // If this argument had no value deduced but was used in one of the types
4618 // used for partial ordering, then deduction fails.
4619 if (Deduced[ArgIdx].isNull() && UsedParameters[ArgIdx])
4625 /// \brief Determine whether this a function template whose parameter-type-list
4626 /// ends with a function parameter pack.
4627 static bool isVariadicFunctionTemplate(FunctionTemplateDecl *FunTmpl) {
4628 FunctionDecl *Function = FunTmpl->getTemplatedDecl();
4629 unsigned NumParams = Function->getNumParams();
4633 ParmVarDecl *Last = Function->getParamDecl(NumParams - 1);
4634 if (!Last->isParameterPack())
4637 // Make sure that no previous parameter is a parameter pack.
4638 while (--NumParams > 0) {
4639 if (Function->getParamDecl(NumParams - 1)->isParameterPack())
4646 /// \brief Returns the more specialized function template according
4647 /// to the rules of function template partial ordering (C++ [temp.func.order]).
4649 /// \param FT1 the first function template
4651 /// \param FT2 the second function template
4653 /// \param TPOC the context in which we are performing partial ordering of
4654 /// function templates.
4656 /// \param NumCallArguments1 The number of arguments in the call to FT1, used
4657 /// only when \c TPOC is \c TPOC_Call.
4659 /// \param NumCallArguments2 The number of arguments in the call to FT2, used
4660 /// only when \c TPOC is \c TPOC_Call.
4662 /// \returns the more specialized function template. If neither
4663 /// template is more specialized, returns NULL.
4664 FunctionTemplateDecl *
4665 Sema::getMoreSpecializedTemplate(FunctionTemplateDecl *FT1,
4666 FunctionTemplateDecl *FT2,
4668 TemplatePartialOrderingContext TPOC,
4669 unsigned NumCallArguments1,
4670 unsigned NumCallArguments2) {
4671 bool Better1 = isAtLeastAsSpecializedAs(*this, Loc, FT1, FT2, TPOC,
4673 bool Better2 = isAtLeastAsSpecializedAs(*this, Loc, FT2, FT1, TPOC,
4676 if (Better1 != Better2) // We have a clear winner
4677 return Better1 ? FT1 : FT2;
4679 if (!Better1 && !Better2) // Neither is better than the other
4682 // FIXME: This mimics what GCC implements, but doesn't match up with the
4683 // proposed resolution for core issue 692. This area needs to be sorted out,
4684 // but for now we attempt to maintain compatibility.
4685 bool Variadic1 = isVariadicFunctionTemplate(FT1);
4686 bool Variadic2 = isVariadicFunctionTemplate(FT2);
4687 if (Variadic1 != Variadic2)
4688 return Variadic1? FT2 : FT1;
4693 /// \brief Determine if the two templates are equivalent.
4694 static bool isSameTemplate(TemplateDecl *T1, TemplateDecl *T2) {
4701 return T1->getCanonicalDecl() == T2->getCanonicalDecl();
4704 /// \brief Retrieve the most specialized of the given function template
4705 /// specializations.
4707 /// \param SpecBegin the start iterator of the function template
4708 /// specializations that we will be comparing.
4710 /// \param SpecEnd the end iterator of the function template
4711 /// specializations, paired with \p SpecBegin.
4713 /// \param Loc the location where the ambiguity or no-specializations
4714 /// diagnostic should occur.
4716 /// \param NoneDiag partial diagnostic used to diagnose cases where there are
4717 /// no matching candidates.
4719 /// \param AmbigDiag partial diagnostic used to diagnose an ambiguity, if one
4722 /// \param CandidateDiag partial diagnostic used for each function template
4723 /// specialization that is a candidate in the ambiguous ordering. One parameter
4724 /// in this diagnostic should be unbound, which will correspond to the string
4725 /// describing the template arguments for the function template specialization.
4727 /// \returns the most specialized function template specialization, if
4728 /// found. Otherwise, returns SpecEnd.
4729 UnresolvedSetIterator Sema::getMostSpecialized(
4730 UnresolvedSetIterator SpecBegin, UnresolvedSetIterator SpecEnd,
4731 TemplateSpecCandidateSet &FailedCandidates,
4732 SourceLocation Loc, const PartialDiagnostic &NoneDiag,
4733 const PartialDiagnostic &AmbigDiag, const PartialDiagnostic &CandidateDiag,
4734 bool Complain, QualType TargetType) {
4735 if (SpecBegin == SpecEnd) {
4737 Diag(Loc, NoneDiag);
4738 FailedCandidates.NoteCandidates(*this, Loc);
4743 if (SpecBegin + 1 == SpecEnd)
4746 // Find the function template that is better than all of the templates it
4747 // has been compared to.
4748 UnresolvedSetIterator Best = SpecBegin;
4749 FunctionTemplateDecl *BestTemplate
4750 = cast<FunctionDecl>(*Best)->getPrimaryTemplate();
4751 assert(BestTemplate && "Not a function template specialization?");
4752 for (UnresolvedSetIterator I = SpecBegin + 1; I != SpecEnd; ++I) {
4753 FunctionTemplateDecl *Challenger
4754 = cast<FunctionDecl>(*I)->getPrimaryTemplate();
4755 assert(Challenger && "Not a function template specialization?");
4756 if (isSameTemplate(getMoreSpecializedTemplate(BestTemplate, Challenger,
4757 Loc, TPOC_Other, 0, 0),
4760 BestTemplate = Challenger;
4764 // Make sure that the "best" function template is more specialized than all
4766 bool Ambiguous = false;
4767 for (UnresolvedSetIterator I = SpecBegin; I != SpecEnd; ++I) {
4768 FunctionTemplateDecl *Challenger
4769 = cast<FunctionDecl>(*I)->getPrimaryTemplate();
4771 !isSameTemplate(getMoreSpecializedTemplate(BestTemplate, Challenger,
4772 Loc, TPOC_Other, 0, 0),
4780 // We found an answer. Return it.
4784 // Diagnose the ambiguity.
4786 Diag(Loc, AmbigDiag);
4788 // FIXME: Can we order the candidates in some sane way?
4789 for (UnresolvedSetIterator I = SpecBegin; I != SpecEnd; ++I) {
4790 PartialDiagnostic PD = CandidateDiag;
4791 const auto *FD = cast<FunctionDecl>(*I);
4792 PD << FD << getTemplateArgumentBindingsText(
4793 FD->getPrimaryTemplate()->getTemplateParameters(),
4794 *FD->getTemplateSpecializationArgs());
4795 if (!TargetType.isNull())
4796 HandleFunctionTypeMismatch(PD, FD->getType(), TargetType);
4797 Diag((*I)->getLocation(), PD);
4804 /// Determine whether one partial specialization, P1, is at least as
4805 /// specialized than another, P2.
4807 /// \tparam TemplateLikeDecl The kind of P2, which must be a
4808 /// TemplateDecl or {Class,Var}TemplatePartialSpecializationDecl.
4809 /// \param T1 The injected-class-name of P1 (faked for a variable template).
4810 /// \param T2 The injected-class-name of P2 (faked for a variable template).
4811 template<typename TemplateLikeDecl>
4812 static bool isAtLeastAsSpecializedAs(Sema &S, QualType T1, QualType T2,
4813 TemplateLikeDecl *P2,
4814 TemplateDeductionInfo &Info) {
4815 // C++ [temp.class.order]p1:
4816 // For two class template partial specializations, the first is at least as
4817 // specialized as the second if, given the following rewrite to two
4818 // function templates, the first function template is at least as
4819 // specialized as the second according to the ordering rules for function
4820 // templates (14.6.6.2):
4821 // - the first function template has the same template parameters as the
4822 // first partial specialization and has a single function parameter
4823 // whose type is a class template specialization with the template
4824 // arguments of the first partial specialization, and
4825 // - the second function template has the same template parameters as the
4826 // second partial specialization and has a single function parameter
4827 // whose type is a class template specialization with the template
4828 // arguments of the second partial specialization.
4830 // Rather than synthesize function templates, we merely perform the
4831 // equivalent partial ordering by performing deduction directly on
4832 // the template arguments of the class template partial
4833 // specializations. This computation is slightly simpler than the
4834 // general problem of function template partial ordering, because
4835 // class template partial specializations are more constrained. We
4836 // know that every template parameter is deducible from the class
4837 // template partial specialization's template arguments, for
4839 SmallVector<DeducedTemplateArgument, 4> Deduced;
4841 // Determine whether P1 is at least as specialized as P2.
4842 Deduced.resize(P2->getTemplateParameters()->size());
4843 if (DeduceTemplateArgumentsByTypeMatch(S, P2->getTemplateParameters(),
4844 T2, T1, Info, Deduced, TDF_None,
4845 /*PartialOrdering=*/true))
4848 SmallVector<TemplateArgument, 4> DeducedArgs(Deduced.begin(),
4850 Sema::InstantiatingTemplate Inst(S, Info.getLocation(), P2, DeducedArgs,
4852 auto *TST1 = T1->castAs<TemplateSpecializationType>();
4853 if (FinishTemplateArgumentDeduction(
4854 S, P2, /*PartialOrdering=*/true,
4855 TemplateArgumentList(TemplateArgumentList::OnStack,
4856 TST1->template_arguments()),
4863 /// \brief Returns the more specialized class template partial specialization
4864 /// according to the rules of partial ordering of class template partial
4865 /// specializations (C++ [temp.class.order]).
4867 /// \param PS1 the first class template partial specialization
4869 /// \param PS2 the second class template partial specialization
4871 /// \returns the more specialized class template partial specialization. If
4872 /// neither partial specialization is more specialized, returns NULL.
4873 ClassTemplatePartialSpecializationDecl *
4874 Sema::getMoreSpecializedPartialSpecialization(
4875 ClassTemplatePartialSpecializationDecl *PS1,
4876 ClassTemplatePartialSpecializationDecl *PS2,
4877 SourceLocation Loc) {
4878 QualType PT1 = PS1->getInjectedSpecializationType();
4879 QualType PT2 = PS2->getInjectedSpecializationType();
4881 TemplateDeductionInfo Info(Loc);
4882 bool Better1 = isAtLeastAsSpecializedAs(*this, PT1, PT2, PS2, Info);
4883 bool Better2 = isAtLeastAsSpecializedAs(*this, PT2, PT1, PS1, Info);
4885 if (Better1 == Better2)
4888 return Better1 ? PS1 : PS2;
4891 bool Sema::isMoreSpecializedThanPrimary(
4892 ClassTemplatePartialSpecializationDecl *Spec, TemplateDeductionInfo &Info) {
4893 ClassTemplateDecl *Primary = Spec->getSpecializedTemplate();
4894 QualType PrimaryT = Primary->getInjectedClassNameSpecialization();
4895 QualType PartialT = Spec->getInjectedSpecializationType();
4896 if (!isAtLeastAsSpecializedAs(*this, PartialT, PrimaryT, Primary, Info))
4898 if (isAtLeastAsSpecializedAs(*this, PrimaryT, PartialT, Spec, Info)) {
4899 Info.clearSFINAEDiagnostic();
4905 VarTemplatePartialSpecializationDecl *
4906 Sema::getMoreSpecializedPartialSpecialization(
4907 VarTemplatePartialSpecializationDecl *PS1,
4908 VarTemplatePartialSpecializationDecl *PS2, SourceLocation Loc) {
4909 // Pretend the variable template specializations are class template
4910 // specializations and form a fake injected class name type for comparison.
4911 assert(PS1->getSpecializedTemplate() == PS2->getSpecializedTemplate() &&
4912 "the partial specializations being compared should specialize"
4913 " the same template.");
4914 TemplateName Name(PS1->getSpecializedTemplate());
4915 TemplateName CanonTemplate = Context.getCanonicalTemplateName(Name);
4916 QualType PT1 = Context.getTemplateSpecializationType(
4917 CanonTemplate, PS1->getTemplateArgs().asArray());
4918 QualType PT2 = Context.getTemplateSpecializationType(
4919 CanonTemplate, PS2->getTemplateArgs().asArray());
4921 TemplateDeductionInfo Info(Loc);
4922 bool Better1 = isAtLeastAsSpecializedAs(*this, PT1, PT2, PS2, Info);
4923 bool Better2 = isAtLeastAsSpecializedAs(*this, PT2, PT1, PS1, Info);
4925 if (Better1 == Better2)
4928 return Better1 ? PS1 : PS2;
4931 bool Sema::isMoreSpecializedThanPrimary(
4932 VarTemplatePartialSpecializationDecl *Spec, TemplateDeductionInfo &Info) {
4933 TemplateDecl *Primary = Spec->getSpecializedTemplate();
4934 // FIXME: Cache the injected template arguments rather than recomputing
4935 // them for each partial specialization.
4936 SmallVector<TemplateArgument, 8> PrimaryArgs;
4937 Context.getInjectedTemplateArgs(Primary->getTemplateParameters(),
4940 TemplateName CanonTemplate =
4941 Context.getCanonicalTemplateName(TemplateName(Primary));
4942 QualType PrimaryT = Context.getTemplateSpecializationType(
4943 CanonTemplate, PrimaryArgs);
4944 QualType PartialT = Context.getTemplateSpecializationType(
4945 CanonTemplate, Spec->getTemplateArgs().asArray());
4946 if (!isAtLeastAsSpecializedAs(*this, PartialT, PrimaryT, Primary, Info))
4948 if (isAtLeastAsSpecializedAs(*this, PrimaryT, PartialT, Spec, Info)) {
4949 Info.clearSFINAEDiagnostic();
4955 bool Sema::isTemplateTemplateParameterAtLeastAsSpecializedAs(
4956 TemplateParameterList *P, TemplateDecl *AArg, SourceLocation Loc) {
4957 // C++1z [temp.arg.template]p4: (DR 150)
4958 // A template template-parameter P is at least as specialized as a
4959 // template template-argument A if, given the following rewrite to two
4960 // function templates...
4962 // Rather than synthesize function templates, we merely perform the
4963 // equivalent partial ordering by performing deduction directly on
4964 // the template parameter lists of the template template parameters.
4966 // Given an invented class template X with the template parameter list of
4967 // A (including default arguments):
4968 TemplateName X = Context.getCanonicalTemplateName(TemplateName(AArg));
4969 TemplateParameterList *A = AArg->getTemplateParameters();
4971 // - Each function template has a single function parameter whose type is
4972 // a specialization of X with template arguments corresponding to the
4973 // template parameters from the respective function template
4974 SmallVector<TemplateArgument, 8> AArgs;
4975 Context.getInjectedTemplateArgs(A, AArgs);
4977 // Check P's arguments against A's parameter list. This will fill in default
4978 // template arguments as needed. AArgs are already correct by construction.
4979 // We can't just use CheckTemplateIdType because that will expand alias
4981 SmallVector<TemplateArgument, 4> PArgs;
4983 SFINAETrap Trap(*this);
4985 Context.getInjectedTemplateArgs(P, PArgs);
4986 TemplateArgumentListInfo PArgList(P->getLAngleLoc(), P->getRAngleLoc());
4987 for (unsigned I = 0, N = P->size(); I != N; ++I) {
4988 // Unwrap packs that getInjectedTemplateArgs wrapped around pack
4989 // expansions, to form an "as written" argument list.
4990 TemplateArgument Arg = PArgs[I];
4991 if (Arg.getKind() == TemplateArgument::Pack) {
4992 assert(Arg.pack_size() == 1 && Arg.pack_begin()->isPackExpansion());
4993 Arg = *Arg.pack_begin();
4995 PArgList.addArgument(getTrivialTemplateArgumentLoc(
4996 Arg, QualType(), P->getParam(I)->getLocation()));
5000 // C++1z [temp.arg.template]p3:
5001 // If the rewrite produces an invalid type, then P is not at least as
5002 // specialized as A.
5003 if (CheckTemplateArgumentList(AArg, Loc, PArgList, false, PArgs) ||
5004 Trap.hasErrorOccurred())
5008 QualType AType = Context.getTemplateSpecializationType(X, AArgs);
5009 QualType PType = Context.getTemplateSpecializationType(X, PArgs);
5011 // ... the function template corresponding to P is at least as specialized
5012 // as the function template corresponding to A according to the partial
5013 // ordering rules for function templates.
5014 TemplateDeductionInfo Info(Loc, A->getDepth());
5015 return isAtLeastAsSpecializedAs(*this, PType, AType, AArg, Info);
5018 /// \brief Mark the template parameters that are used by the given
5021 MarkUsedTemplateParameters(ASTContext &Ctx,
5025 llvm::SmallBitVector &Used) {
5026 // We can deduce from a pack expansion.
5027 if (const PackExpansionExpr *Expansion = dyn_cast<PackExpansionExpr>(E))
5028 E = Expansion->getPattern();
5030 // Skip through any implicit casts we added while type-checking, and any
5031 // substitutions performed by template alias expansion.
5033 if (const ImplicitCastExpr *ICE = dyn_cast<ImplicitCastExpr>(E))
5034 E = ICE->getSubExpr();
5035 else if (const SubstNonTypeTemplateParmExpr *Subst =
5036 dyn_cast<SubstNonTypeTemplateParmExpr>(E))
5037 E = Subst->getReplacement();
5042 // FIXME: if !OnlyDeduced, we have to walk the whole subexpression to
5043 // find other occurrences of template parameters.
5044 const DeclRefExpr *DRE = dyn_cast<DeclRefExpr>(E);
5048 const NonTypeTemplateParmDecl *NTTP
5049 = dyn_cast<NonTypeTemplateParmDecl>(DRE->getDecl());
5053 if (NTTP->getDepth() == Depth)
5054 Used[NTTP->getIndex()] = true;
5056 // In C++17 mode, additional arguments may be deduced from the type of a
5057 // non-type argument.
5058 if (Ctx.getLangOpts().CPlusPlus17)
5059 MarkUsedTemplateParameters(Ctx, NTTP->getType(), OnlyDeduced, Depth, Used);
5062 /// \brief Mark the template parameters that are used by the given
5063 /// nested name specifier.
5065 MarkUsedTemplateParameters(ASTContext &Ctx,
5066 NestedNameSpecifier *NNS,
5069 llvm::SmallBitVector &Used) {
5073 MarkUsedTemplateParameters(Ctx, NNS->getPrefix(), OnlyDeduced, Depth,
5075 MarkUsedTemplateParameters(Ctx, QualType(NNS->getAsType(), 0),
5076 OnlyDeduced, Depth, Used);
5079 /// \brief Mark the template parameters that are used by the given
5082 MarkUsedTemplateParameters(ASTContext &Ctx,
5086 llvm::SmallBitVector &Used) {
5087 if (TemplateDecl *Template = Name.getAsTemplateDecl()) {
5088 if (TemplateTemplateParmDecl *TTP
5089 = dyn_cast<TemplateTemplateParmDecl>(Template)) {
5090 if (TTP->getDepth() == Depth)
5091 Used[TTP->getIndex()] = true;
5096 if (QualifiedTemplateName *QTN = Name.getAsQualifiedTemplateName())
5097 MarkUsedTemplateParameters(Ctx, QTN->getQualifier(), OnlyDeduced,
5099 if (DependentTemplateName *DTN = Name.getAsDependentTemplateName())
5100 MarkUsedTemplateParameters(Ctx, DTN->getQualifier(), OnlyDeduced,
5104 /// \brief Mark the template parameters that are used by the given
5107 MarkUsedTemplateParameters(ASTContext &Ctx, QualType T,
5110 llvm::SmallBitVector &Used) {
5114 // Non-dependent types have nothing deducible
5115 if (!T->isDependentType())
5118 T = Ctx.getCanonicalType(T);
5119 switch (T->getTypeClass()) {
5121 MarkUsedTemplateParameters(Ctx,
5122 cast<PointerType>(T)->getPointeeType(),
5128 case Type::BlockPointer:
5129 MarkUsedTemplateParameters(Ctx,
5130 cast<BlockPointerType>(T)->getPointeeType(),
5136 case Type::LValueReference:
5137 case Type::RValueReference:
5138 MarkUsedTemplateParameters(Ctx,
5139 cast<ReferenceType>(T)->getPointeeType(),
5145 case Type::MemberPointer: {
5146 const MemberPointerType *MemPtr = cast<MemberPointerType>(T.getTypePtr());
5147 MarkUsedTemplateParameters(Ctx, MemPtr->getPointeeType(), OnlyDeduced,
5149 MarkUsedTemplateParameters(Ctx, QualType(MemPtr->getClass(), 0),
5150 OnlyDeduced, Depth, Used);
5154 case Type::DependentSizedArray:
5155 MarkUsedTemplateParameters(Ctx,
5156 cast<DependentSizedArrayType>(T)->getSizeExpr(),
5157 OnlyDeduced, Depth, Used);
5158 // Fall through to check the element type
5161 case Type::ConstantArray:
5162 case Type::IncompleteArray:
5163 MarkUsedTemplateParameters(Ctx,
5164 cast<ArrayType>(T)->getElementType(),
5165 OnlyDeduced, Depth, Used);
5169 case Type::ExtVector:
5170 MarkUsedTemplateParameters(Ctx,
5171 cast<VectorType>(T)->getElementType(),
5172 OnlyDeduced, Depth, Used);
5175 case Type::DependentSizedExtVector: {
5176 const DependentSizedExtVectorType *VecType
5177 = cast<DependentSizedExtVectorType>(T);
5178 MarkUsedTemplateParameters(Ctx, VecType->getElementType(), OnlyDeduced,
5180 MarkUsedTemplateParameters(Ctx, VecType->getSizeExpr(), OnlyDeduced,
5185 case Type::DependentAddressSpace: {
5186 const DependentAddressSpaceType *DependentASType =
5187 cast<DependentAddressSpaceType>(T);
5188 MarkUsedTemplateParameters(Ctx, DependentASType->getPointeeType(),
5189 OnlyDeduced, Depth, Used);
5190 MarkUsedTemplateParameters(Ctx,
5191 DependentASType->getAddrSpaceExpr(),
5192 OnlyDeduced, Depth, Used);
5196 case Type::FunctionProto: {
5197 const FunctionProtoType *Proto = cast<FunctionProtoType>(T);
5198 MarkUsedTemplateParameters(Ctx, Proto->getReturnType(), OnlyDeduced, Depth,
5200 for (unsigned I = 0, N = Proto->getNumParams(); I != N; ++I)
5201 MarkUsedTemplateParameters(Ctx, Proto->getParamType(I), OnlyDeduced,
5203 if (auto *E = Proto->getNoexceptExpr())
5204 MarkUsedTemplateParameters(Ctx, E, OnlyDeduced, Depth, Used);
5208 case Type::TemplateTypeParm: {
5209 const TemplateTypeParmType *TTP = cast<TemplateTypeParmType>(T);
5210 if (TTP->getDepth() == Depth)
5211 Used[TTP->getIndex()] = true;
5215 case Type::SubstTemplateTypeParmPack: {
5216 const SubstTemplateTypeParmPackType *Subst
5217 = cast<SubstTemplateTypeParmPackType>(T);
5218 MarkUsedTemplateParameters(Ctx,
5219 QualType(Subst->getReplacedParameter(), 0),
5220 OnlyDeduced, Depth, Used);
5221 MarkUsedTemplateParameters(Ctx, Subst->getArgumentPack(),
5222 OnlyDeduced, Depth, Used);
5226 case Type::InjectedClassName:
5227 T = cast<InjectedClassNameType>(T)->getInjectedSpecializationType();
5230 case Type::TemplateSpecialization: {
5231 const TemplateSpecializationType *Spec
5232 = cast<TemplateSpecializationType>(T);
5233 MarkUsedTemplateParameters(Ctx, Spec->getTemplateName(), OnlyDeduced,
5236 // C++0x [temp.deduct.type]p9:
5237 // If the template argument list of P contains a pack expansion that is
5238 // not the last template argument, the entire template argument list is a
5239 // non-deduced context.
5241 hasPackExpansionBeforeEnd(Spec->template_arguments()))
5244 for (unsigned I = 0, N = Spec->getNumArgs(); I != N; ++I)
5245 MarkUsedTemplateParameters(Ctx, Spec->getArg(I), OnlyDeduced, Depth,
5252 MarkUsedTemplateParameters(Ctx,
5253 cast<ComplexType>(T)->getElementType(),
5254 OnlyDeduced, Depth, Used);
5259 MarkUsedTemplateParameters(Ctx,
5260 cast<AtomicType>(T)->getValueType(),
5261 OnlyDeduced, Depth, Used);
5264 case Type::DependentName:
5266 MarkUsedTemplateParameters(Ctx,
5267 cast<DependentNameType>(T)->getQualifier(),
5268 OnlyDeduced, Depth, Used);
5271 case Type::DependentTemplateSpecialization: {
5272 // C++14 [temp.deduct.type]p5:
5273 // The non-deduced contexts are:
5274 // -- The nested-name-specifier of a type that was specified using a
5277 // C++14 [temp.deduct.type]p6:
5278 // When a type name is specified in a way that includes a non-deduced
5279 // context, all of the types that comprise that type name are also
5284 const DependentTemplateSpecializationType *Spec
5285 = cast<DependentTemplateSpecializationType>(T);
5287 MarkUsedTemplateParameters(Ctx, Spec->getQualifier(),
5288 OnlyDeduced, Depth, Used);
5290 for (unsigned I = 0, N = Spec->getNumArgs(); I != N; ++I)
5291 MarkUsedTemplateParameters(Ctx, Spec->getArg(I), OnlyDeduced, Depth,
5298 MarkUsedTemplateParameters(Ctx,
5299 cast<TypeOfType>(T)->getUnderlyingType(),
5300 OnlyDeduced, Depth, Used);
5303 case Type::TypeOfExpr:
5305 MarkUsedTemplateParameters(Ctx,
5306 cast<TypeOfExprType>(T)->getUnderlyingExpr(),
5307 OnlyDeduced, Depth, Used);
5310 case Type::Decltype:
5312 MarkUsedTemplateParameters(Ctx,
5313 cast<DecltypeType>(T)->getUnderlyingExpr(),
5314 OnlyDeduced, Depth, Used);
5317 case Type::UnaryTransform:
5319 MarkUsedTemplateParameters(Ctx,
5320 cast<UnaryTransformType>(T)->getUnderlyingType(),
5321 OnlyDeduced, Depth, Used);
5324 case Type::PackExpansion:
5325 MarkUsedTemplateParameters(Ctx,
5326 cast<PackExpansionType>(T)->getPattern(),
5327 OnlyDeduced, Depth, Used);
5331 case Type::DeducedTemplateSpecialization:
5332 MarkUsedTemplateParameters(Ctx,
5333 cast<DeducedType>(T)->getDeducedType(),
5334 OnlyDeduced, Depth, Used);
5337 // None of these types have any template parameters in them.
5339 case Type::VariableArray:
5340 case Type::FunctionNoProto:
5343 case Type::ObjCInterface:
5344 case Type::ObjCObject:
5345 case Type::ObjCObjectPointer:
5346 case Type::UnresolvedUsing:
5348 #define TYPE(Class, Base)
5349 #define ABSTRACT_TYPE(Class, Base)
5350 #define DEPENDENT_TYPE(Class, Base)
5351 #define NON_CANONICAL_TYPE(Class, Base) case Type::Class:
5352 #include "clang/AST/TypeNodes.def"
5357 /// \brief Mark the template parameters that are used by this
5358 /// template argument.
5360 MarkUsedTemplateParameters(ASTContext &Ctx,
5361 const TemplateArgument &TemplateArg,
5364 llvm::SmallBitVector &Used) {
5365 switch (TemplateArg.getKind()) {
5366 case TemplateArgument::Null:
5367 case TemplateArgument::Integral:
5368 case TemplateArgument::Declaration:
5371 case TemplateArgument::NullPtr:
5372 MarkUsedTemplateParameters(Ctx, TemplateArg.getNullPtrType(), OnlyDeduced,
5376 case TemplateArgument::Type:
5377 MarkUsedTemplateParameters(Ctx, TemplateArg.getAsType(), OnlyDeduced,
5381 case TemplateArgument::Template:
5382 case TemplateArgument::TemplateExpansion:
5383 MarkUsedTemplateParameters(Ctx,
5384 TemplateArg.getAsTemplateOrTemplatePattern(),
5385 OnlyDeduced, Depth, Used);
5388 case TemplateArgument::Expression:
5389 MarkUsedTemplateParameters(Ctx, TemplateArg.getAsExpr(), OnlyDeduced,
5393 case TemplateArgument::Pack:
5394 for (const auto &P : TemplateArg.pack_elements())
5395 MarkUsedTemplateParameters(Ctx, P, OnlyDeduced, Depth, Used);
5400 /// \brief Mark which template parameters can be deduced from a given
5401 /// template argument list.
5403 /// \param TemplateArgs the template argument list from which template
5404 /// parameters will be deduced.
5406 /// \param Used a bit vector whose elements will be set to \c true
5407 /// to indicate when the corresponding template parameter will be
5410 Sema::MarkUsedTemplateParameters(const TemplateArgumentList &TemplateArgs,
5411 bool OnlyDeduced, unsigned Depth,
5412 llvm::SmallBitVector &Used) {
5413 // C++0x [temp.deduct.type]p9:
5414 // If the template argument list of P contains a pack expansion that is not
5415 // the last template argument, the entire template argument list is a
5416 // non-deduced context.
5418 hasPackExpansionBeforeEnd(TemplateArgs.asArray()))
5421 for (unsigned I = 0, N = TemplateArgs.size(); I != N; ++I)
5422 ::MarkUsedTemplateParameters(Context, TemplateArgs[I], OnlyDeduced,
5426 /// \brief Marks all of the template parameters that will be deduced by a
5427 /// call to the given function template.
5428 void Sema::MarkDeducedTemplateParameters(
5429 ASTContext &Ctx, const FunctionTemplateDecl *FunctionTemplate,
5430 llvm::SmallBitVector &Deduced) {
5431 TemplateParameterList *TemplateParams
5432 = FunctionTemplate->getTemplateParameters();
5434 Deduced.resize(TemplateParams->size());
5436 FunctionDecl *Function = FunctionTemplate->getTemplatedDecl();
5437 for (unsigned I = 0, N = Function->getNumParams(); I != N; ++I)
5438 ::MarkUsedTemplateParameters(Ctx, Function->getParamDecl(I)->getType(),
5439 true, TemplateParams->getDepth(), Deduced);
5442 bool hasDeducibleTemplateParameters(Sema &S,
5443 FunctionTemplateDecl *FunctionTemplate,
5445 if (!T->isDependentType())
5448 TemplateParameterList *TemplateParams
5449 = FunctionTemplate->getTemplateParameters();
5450 llvm::SmallBitVector Deduced(TemplateParams->size());
5451 ::MarkUsedTemplateParameters(S.Context, T, true, TemplateParams->getDepth(),
5454 return Deduced.any();