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/Sema/DeclSpec.h"
23 #include "clang/Sema/Sema.h"
24 #include "clang/Sema/Template.h"
25 #include "llvm/ADT/SmallBitVector.h"
30 /// \brief Various flags that control template argument deduction.
32 /// These flags can be bitwise-OR'd together.
33 enum TemplateDeductionFlags {
34 /// \brief No template argument deduction flags, which indicates the
35 /// strictest results for template argument deduction (as used for, e.g.,
36 /// matching class template partial specializations).
38 /// \brief Within template argument deduction from a function call, we are
39 /// matching with a parameter type for which the original parameter was
41 TDF_ParamWithReferenceType = 0x1,
42 /// \brief Within template argument deduction from a function call, we
43 /// are matching in a case where we ignore cv-qualifiers.
44 TDF_IgnoreQualifiers = 0x02,
45 /// \brief Within template argument deduction from a function call,
46 /// we are matching in a case where we can perform template argument
47 /// deduction from a template-id of a derived class of the argument type.
48 TDF_DerivedClass = 0x04,
49 /// \brief Allow non-dependent types to differ, e.g., when performing
50 /// template argument deduction from a function call where conversions
52 TDF_SkipNonDependent = 0x08,
53 /// \brief Whether we are performing template argument deduction for
54 /// parameters and arguments in a top-level template argument
55 TDF_TopLevelParameterTypeList = 0x10,
56 /// \brief Within template argument deduction from overload resolution per
57 /// C++ [over.over] allow matching function types that are compatible in
58 /// terms of noreturn and default calling convention adjustments.
59 TDF_InOverloadResolution = 0x20
63 using namespace clang;
65 /// \brief Compare two APSInts, extending and switching the sign as
66 /// necessary to compare their values regardless of underlying type.
67 static bool hasSameExtendedValue(llvm::APSInt X, llvm::APSInt Y) {
68 if (Y.getBitWidth() > X.getBitWidth())
69 X = X.extend(Y.getBitWidth());
70 else if (Y.getBitWidth() < X.getBitWidth())
71 Y = Y.extend(X.getBitWidth());
73 // If there is a signedness mismatch, correct it.
74 if (X.isSigned() != Y.isSigned()) {
75 // If the signed value is negative, then the values cannot be the same.
76 if ((Y.isSigned() && Y.isNegative()) || (X.isSigned() && X.isNegative()))
86 static Sema::TemplateDeductionResult
87 DeduceTemplateArguments(Sema &S,
88 TemplateParameterList *TemplateParams,
89 const TemplateArgument &Param,
91 TemplateDeductionInfo &Info,
92 SmallVectorImpl<DeducedTemplateArgument> &Deduced);
94 /// \brief Whether template argument deduction for two reference parameters
95 /// resulted in the argument type, parameter type, or neither type being more
96 /// qualified than the other.
97 enum DeductionQualifierComparison {
98 NeitherMoreQualified = 0,
103 /// \brief Stores the result of comparing two reference parameters while
104 /// performing template argument deduction for partial ordering of function
106 struct RefParamPartialOrderingComparison {
107 /// \brief Whether the parameter type is an rvalue reference type.
108 bool ParamIsRvalueRef;
109 /// \brief Whether the argument type is an rvalue reference type.
112 /// \brief Whether the parameter or argument (or neither) is more qualified.
113 DeductionQualifierComparison Qualifiers;
118 static Sema::TemplateDeductionResult
119 DeduceTemplateArgumentsByTypeMatch(Sema &S,
120 TemplateParameterList *TemplateParams,
123 TemplateDeductionInfo &Info,
124 SmallVectorImpl<DeducedTemplateArgument> &
127 bool PartialOrdering = false,
128 SmallVectorImpl<RefParamPartialOrderingComparison> *
129 RefParamComparisons = nullptr);
131 static Sema::TemplateDeductionResult
132 DeduceTemplateArguments(Sema &S,
133 TemplateParameterList *TemplateParams,
134 const TemplateArgument *Params, unsigned NumParams,
135 const TemplateArgument *Args, unsigned NumArgs,
136 TemplateDeductionInfo &Info,
137 SmallVectorImpl<DeducedTemplateArgument> &Deduced);
139 /// \brief If the given expression is of a form that permits the deduction
140 /// of a non-type template parameter, return the declaration of that
141 /// non-type template parameter.
142 static NonTypeTemplateParmDecl *getDeducedParameterFromExpr(Expr *E) {
143 // If we are within an alias template, the expression may have undergone
144 // any number of parameter substitutions already.
146 if (ImplicitCastExpr *IC = dyn_cast<ImplicitCastExpr>(E))
147 E = IC->getSubExpr();
148 else if (SubstNonTypeTemplateParmExpr *Subst =
149 dyn_cast<SubstNonTypeTemplateParmExpr>(E))
150 E = Subst->getReplacement();
155 if (DeclRefExpr *DRE = dyn_cast<DeclRefExpr>(E))
156 return dyn_cast<NonTypeTemplateParmDecl>(DRE->getDecl());
161 /// \brief Determine whether two declaration pointers refer to the same
163 static bool isSameDeclaration(Decl *X, Decl *Y) {
164 if (NamedDecl *NX = dyn_cast<NamedDecl>(X))
165 X = NX->getUnderlyingDecl();
166 if (NamedDecl *NY = dyn_cast<NamedDecl>(Y))
167 Y = NY->getUnderlyingDecl();
169 return X->getCanonicalDecl() == Y->getCanonicalDecl();
172 /// \brief Verify that the given, deduced template arguments are compatible.
174 /// \returns The deduced template argument, or a NULL template argument if
175 /// the deduced template arguments were incompatible.
176 static DeducedTemplateArgument
177 checkDeducedTemplateArguments(ASTContext &Context,
178 const DeducedTemplateArgument &X,
179 const DeducedTemplateArgument &Y) {
180 // We have no deduction for one or both of the arguments; they're compatible.
186 switch (X.getKind()) {
187 case TemplateArgument::Null:
188 llvm_unreachable("Non-deduced template arguments handled above");
190 case TemplateArgument::Type:
191 // If two template type arguments have the same type, they're compatible.
192 if (Y.getKind() == TemplateArgument::Type &&
193 Context.hasSameType(X.getAsType(), Y.getAsType()))
196 return DeducedTemplateArgument();
198 case TemplateArgument::Integral:
199 // If we deduced a constant in one case and either a dependent expression or
200 // declaration in another case, keep the integral constant.
201 // If both are integral constants with the same value, keep that value.
202 if (Y.getKind() == TemplateArgument::Expression ||
203 Y.getKind() == TemplateArgument::Declaration ||
204 (Y.getKind() == TemplateArgument::Integral &&
205 hasSameExtendedValue(X.getAsIntegral(), Y.getAsIntegral())))
206 return DeducedTemplateArgument(X,
207 X.wasDeducedFromArrayBound() &&
208 Y.wasDeducedFromArrayBound());
210 // All other combinations are incompatible.
211 return DeducedTemplateArgument();
213 case TemplateArgument::Template:
214 if (Y.getKind() == TemplateArgument::Template &&
215 Context.hasSameTemplateName(X.getAsTemplate(), Y.getAsTemplate()))
218 // All other combinations are incompatible.
219 return DeducedTemplateArgument();
221 case TemplateArgument::TemplateExpansion:
222 if (Y.getKind() == TemplateArgument::TemplateExpansion &&
223 Context.hasSameTemplateName(X.getAsTemplateOrTemplatePattern(),
224 Y.getAsTemplateOrTemplatePattern()))
227 // All other combinations are incompatible.
228 return DeducedTemplateArgument();
230 case TemplateArgument::Expression:
231 // If we deduced a dependent expression in one case and either an integral
232 // constant or a declaration in another case, keep the integral constant
234 if (Y.getKind() == TemplateArgument::Integral ||
235 Y.getKind() == TemplateArgument::Declaration)
236 return DeducedTemplateArgument(Y, X.wasDeducedFromArrayBound() &&
237 Y.wasDeducedFromArrayBound());
239 if (Y.getKind() == TemplateArgument::Expression) {
240 // Compare the expressions for equality
241 llvm::FoldingSetNodeID ID1, ID2;
242 X.getAsExpr()->Profile(ID1, Context, true);
243 Y.getAsExpr()->Profile(ID2, Context, true);
248 // All other combinations are incompatible.
249 return DeducedTemplateArgument();
251 case TemplateArgument::Declaration:
252 // If we deduced a declaration and a dependent expression, keep the
254 if (Y.getKind() == TemplateArgument::Expression)
257 // If we deduced a declaration and an integral constant, keep the
258 // integral constant.
259 if (Y.getKind() == TemplateArgument::Integral)
262 // If we deduced two declarations, make sure they they refer to the
264 if (Y.getKind() == TemplateArgument::Declaration &&
265 isSameDeclaration(X.getAsDecl(), Y.getAsDecl()))
268 // All other combinations are incompatible.
269 return DeducedTemplateArgument();
271 case TemplateArgument::NullPtr:
272 // If we deduced a null pointer and a dependent expression, keep the
274 if (Y.getKind() == TemplateArgument::Expression)
277 // If we deduced a null pointer and an integral constant, keep the
278 // integral constant.
279 if (Y.getKind() == TemplateArgument::Integral)
282 // If we deduced two null pointers, make sure they have the same type.
283 if (Y.getKind() == TemplateArgument::NullPtr &&
284 Context.hasSameType(X.getNullPtrType(), Y.getNullPtrType()))
287 // All other combinations are incompatible.
288 return DeducedTemplateArgument();
290 case TemplateArgument::Pack:
291 if (Y.getKind() != TemplateArgument::Pack ||
292 X.pack_size() != Y.pack_size())
293 return DeducedTemplateArgument();
295 for (TemplateArgument::pack_iterator XA = X.pack_begin(),
296 XAEnd = X.pack_end(),
298 XA != XAEnd; ++XA, ++YA) {
299 // FIXME: Do we need to merge the results together here?
300 if (checkDeducedTemplateArguments(Context,
301 DeducedTemplateArgument(*XA, X.wasDeducedFromArrayBound()),
302 DeducedTemplateArgument(*YA, Y.wasDeducedFromArrayBound()))
304 return DeducedTemplateArgument();
310 llvm_unreachable("Invalid TemplateArgument Kind!");
313 /// \brief Deduce the value of the given non-type template parameter
314 /// from the given constant.
315 static Sema::TemplateDeductionResult
316 DeduceNonTypeTemplateArgument(Sema &S,
317 NonTypeTemplateParmDecl *NTTP,
318 llvm::APSInt Value, QualType ValueType,
319 bool DeducedFromArrayBound,
320 TemplateDeductionInfo &Info,
321 SmallVectorImpl<DeducedTemplateArgument> &Deduced) {
322 assert(NTTP->getDepth() == 0 &&
323 "Cannot deduce non-type template argument with depth > 0");
325 DeducedTemplateArgument NewDeduced(S.Context, Value, ValueType,
326 DeducedFromArrayBound);
327 DeducedTemplateArgument Result = checkDeducedTemplateArguments(S.Context,
328 Deduced[NTTP->getIndex()],
330 if (Result.isNull()) {
332 Info.FirstArg = Deduced[NTTP->getIndex()];
333 Info.SecondArg = NewDeduced;
334 return Sema::TDK_Inconsistent;
337 Deduced[NTTP->getIndex()] = Result;
338 return Sema::TDK_Success;
341 /// \brief Deduce the value of the given non-type template parameter
342 /// from the given type- or value-dependent expression.
344 /// \returns true if deduction succeeded, false otherwise.
345 static Sema::TemplateDeductionResult
346 DeduceNonTypeTemplateArgument(Sema &S,
347 NonTypeTemplateParmDecl *NTTP,
349 TemplateDeductionInfo &Info,
350 SmallVectorImpl<DeducedTemplateArgument> &Deduced) {
351 assert(NTTP->getDepth() == 0 &&
352 "Cannot deduce non-type template argument with depth > 0");
353 assert((Value->isTypeDependent() || Value->isValueDependent()) &&
354 "Expression template argument must be type- or value-dependent.");
356 DeducedTemplateArgument NewDeduced(Value);
357 DeducedTemplateArgument Result = checkDeducedTemplateArguments(S.Context,
358 Deduced[NTTP->getIndex()],
361 if (Result.isNull()) {
363 Info.FirstArg = Deduced[NTTP->getIndex()];
364 Info.SecondArg = NewDeduced;
365 return Sema::TDK_Inconsistent;
368 Deduced[NTTP->getIndex()] = Result;
369 return Sema::TDK_Success;
372 /// \brief Deduce the value of the given non-type template parameter
373 /// from the given declaration.
375 /// \returns true if deduction succeeded, false otherwise.
376 static Sema::TemplateDeductionResult
377 DeduceNonTypeTemplateArgument(Sema &S,
378 NonTypeTemplateParmDecl *NTTP,
380 TemplateDeductionInfo &Info,
381 SmallVectorImpl<DeducedTemplateArgument> &Deduced) {
382 assert(NTTP->getDepth() == 0 &&
383 "Cannot deduce non-type template argument with depth > 0");
385 D = D ? cast<ValueDecl>(D->getCanonicalDecl()) : nullptr;
386 TemplateArgument New(D, NTTP->getType());
387 DeducedTemplateArgument NewDeduced(New);
388 DeducedTemplateArgument Result = checkDeducedTemplateArguments(S.Context,
389 Deduced[NTTP->getIndex()],
391 if (Result.isNull()) {
393 Info.FirstArg = Deduced[NTTP->getIndex()];
394 Info.SecondArg = NewDeduced;
395 return Sema::TDK_Inconsistent;
398 Deduced[NTTP->getIndex()] = Result;
399 return Sema::TDK_Success;
402 static Sema::TemplateDeductionResult
403 DeduceTemplateArguments(Sema &S,
404 TemplateParameterList *TemplateParams,
407 TemplateDeductionInfo &Info,
408 SmallVectorImpl<DeducedTemplateArgument> &Deduced) {
409 TemplateDecl *ParamDecl = Param.getAsTemplateDecl();
411 // The parameter type is dependent and is not a template template parameter,
412 // so there is nothing that we can deduce.
413 return Sema::TDK_Success;
416 if (TemplateTemplateParmDecl *TempParam
417 = dyn_cast<TemplateTemplateParmDecl>(ParamDecl)) {
418 DeducedTemplateArgument NewDeduced(S.Context.getCanonicalTemplateName(Arg));
419 DeducedTemplateArgument Result = checkDeducedTemplateArguments(S.Context,
420 Deduced[TempParam->getIndex()],
422 if (Result.isNull()) {
423 Info.Param = TempParam;
424 Info.FirstArg = Deduced[TempParam->getIndex()];
425 Info.SecondArg = NewDeduced;
426 return Sema::TDK_Inconsistent;
429 Deduced[TempParam->getIndex()] = Result;
430 return Sema::TDK_Success;
433 // Verify that the two template names are equivalent.
434 if (S.Context.hasSameTemplateName(Param, Arg))
435 return Sema::TDK_Success;
437 // Mismatch of non-dependent template parameter to argument.
438 Info.FirstArg = TemplateArgument(Param);
439 Info.SecondArg = TemplateArgument(Arg);
440 return Sema::TDK_NonDeducedMismatch;
443 /// \brief Deduce the template arguments by comparing the template parameter
444 /// type (which is a template-id) with the template argument type.
446 /// \param S the Sema
448 /// \param TemplateParams the template parameters that we are deducing
450 /// \param Param the parameter type
452 /// \param Arg the argument type
454 /// \param Info information about the template argument deduction itself
456 /// \param Deduced the deduced template arguments
458 /// \returns the result of template argument deduction so far. Note that a
459 /// "success" result means that template argument deduction has not yet failed,
460 /// but it may still fail, later, for other reasons.
461 static Sema::TemplateDeductionResult
462 DeduceTemplateArguments(Sema &S,
463 TemplateParameterList *TemplateParams,
464 const TemplateSpecializationType *Param,
466 TemplateDeductionInfo &Info,
467 SmallVectorImpl<DeducedTemplateArgument> &Deduced) {
468 assert(Arg.isCanonical() && "Argument type must be canonical");
470 // Check whether the template argument is a dependent template-id.
471 if (const TemplateSpecializationType *SpecArg
472 = dyn_cast<TemplateSpecializationType>(Arg)) {
473 // Perform template argument deduction for the template name.
474 if (Sema::TemplateDeductionResult Result
475 = DeduceTemplateArguments(S, TemplateParams,
476 Param->getTemplateName(),
477 SpecArg->getTemplateName(),
482 // Perform template argument deduction on each template
483 // argument. Ignore any missing/extra arguments, since they could be
484 // filled in by default arguments.
485 return DeduceTemplateArguments(S, TemplateParams,
486 Param->getArgs(), Param->getNumArgs(),
487 SpecArg->getArgs(), SpecArg->getNumArgs(),
491 // If the argument type is a class template specialization, we
492 // perform template argument deduction using its template
494 const RecordType *RecordArg = dyn_cast<RecordType>(Arg);
496 Info.FirstArg = TemplateArgument(QualType(Param, 0));
497 Info.SecondArg = TemplateArgument(Arg);
498 return Sema::TDK_NonDeducedMismatch;
501 ClassTemplateSpecializationDecl *SpecArg
502 = dyn_cast<ClassTemplateSpecializationDecl>(RecordArg->getDecl());
504 Info.FirstArg = TemplateArgument(QualType(Param, 0));
505 Info.SecondArg = TemplateArgument(Arg);
506 return Sema::TDK_NonDeducedMismatch;
509 // Perform template argument deduction for the template name.
510 if (Sema::TemplateDeductionResult Result
511 = DeduceTemplateArguments(S,
513 Param->getTemplateName(),
514 TemplateName(SpecArg->getSpecializedTemplate()),
518 // Perform template argument deduction for the template arguments.
519 return DeduceTemplateArguments(S, TemplateParams,
520 Param->getArgs(), Param->getNumArgs(),
521 SpecArg->getTemplateArgs().data(),
522 SpecArg->getTemplateArgs().size(),
526 /// \brief Determines whether the given type is an opaque type that
527 /// might be more qualified when instantiated.
528 static bool IsPossiblyOpaquelyQualifiedType(QualType T) {
529 switch (T->getTypeClass()) {
530 case Type::TypeOfExpr:
532 case Type::DependentName:
534 case Type::UnresolvedUsing:
535 case Type::TemplateTypeParm:
538 case Type::ConstantArray:
539 case Type::IncompleteArray:
540 case Type::VariableArray:
541 case Type::DependentSizedArray:
542 return IsPossiblyOpaquelyQualifiedType(
543 cast<ArrayType>(T)->getElementType());
550 /// \brief Retrieve the depth and index of a template parameter.
551 static std::pair<unsigned, unsigned>
552 getDepthAndIndex(NamedDecl *ND) {
553 if (TemplateTypeParmDecl *TTP = dyn_cast<TemplateTypeParmDecl>(ND))
554 return std::make_pair(TTP->getDepth(), TTP->getIndex());
556 if (NonTypeTemplateParmDecl *NTTP = dyn_cast<NonTypeTemplateParmDecl>(ND))
557 return std::make_pair(NTTP->getDepth(), NTTP->getIndex());
559 TemplateTemplateParmDecl *TTP = cast<TemplateTemplateParmDecl>(ND);
560 return std::make_pair(TTP->getDepth(), TTP->getIndex());
563 /// \brief Retrieve the depth and index of an unexpanded parameter pack.
564 static std::pair<unsigned, unsigned>
565 getDepthAndIndex(UnexpandedParameterPack UPP) {
566 if (const TemplateTypeParmType *TTP
567 = UPP.first.dyn_cast<const TemplateTypeParmType *>())
568 return std::make_pair(TTP->getDepth(), TTP->getIndex());
570 return getDepthAndIndex(UPP.first.get<NamedDecl *>());
573 /// \brief Helper function to build a TemplateParameter when we don't
574 /// know its type statically.
575 static TemplateParameter makeTemplateParameter(Decl *D) {
576 if (TemplateTypeParmDecl *TTP = dyn_cast<TemplateTypeParmDecl>(D))
577 return TemplateParameter(TTP);
578 if (NonTypeTemplateParmDecl *NTTP = dyn_cast<NonTypeTemplateParmDecl>(D))
579 return TemplateParameter(NTTP);
581 return TemplateParameter(cast<TemplateTemplateParmDecl>(D));
584 /// A pack that we're currently deducing.
585 struct clang::DeducedPack {
586 DeducedPack(unsigned Index) : Index(Index), Outer(nullptr) {}
588 // The index of the pack.
591 // The old value of the pack before we started deducing it.
592 DeducedTemplateArgument Saved;
594 // A deferred value of this pack from an inner deduction, that couldn't be
595 // deduced because this deduction hadn't happened yet.
596 DeducedTemplateArgument DeferredDeduction;
598 // The new value of the pack.
599 SmallVector<DeducedTemplateArgument, 4> New;
601 // The outer deduction for this pack, if any.
605 /// A scope in which we're performing pack deduction.
606 class PackDeductionScope {
608 PackDeductionScope(Sema &S, TemplateParameterList *TemplateParams,
609 SmallVectorImpl<DeducedTemplateArgument> &Deduced,
610 TemplateDeductionInfo &Info, TemplateArgument Pattern)
611 : S(S), TemplateParams(TemplateParams), Deduced(Deduced), Info(Info) {
612 // Compute the set of template parameter indices that correspond to
613 // parameter packs expanded by the pack expansion.
615 llvm::SmallBitVector SawIndices(TemplateParams->size());
616 SmallVector<UnexpandedParameterPack, 2> Unexpanded;
617 S.collectUnexpandedParameterPacks(Pattern, Unexpanded);
618 for (unsigned I = 0, N = Unexpanded.size(); I != N; ++I) {
619 unsigned Depth, Index;
620 std::tie(Depth, Index) = getDepthAndIndex(Unexpanded[I]);
621 if (Depth == 0 && !SawIndices[Index]) {
622 SawIndices[Index] = true;
624 // Save the deduced template argument for the parameter pack expanded
625 // by this pack expansion, then clear out the deduction.
626 DeducedPack Pack(Index);
627 Pack.Saved = Deduced[Index];
628 Deduced[Index] = TemplateArgument();
630 Packs.push_back(Pack);
634 assert(!Packs.empty() && "Pack expansion without unexpanded packs?");
636 for (auto &Pack : Packs) {
637 if (Info.PendingDeducedPacks.size() > Pack.Index)
638 Pack.Outer = Info.PendingDeducedPacks[Pack.Index];
640 Info.PendingDeducedPacks.resize(Pack.Index + 1);
641 Info.PendingDeducedPacks[Pack.Index] = &Pack;
643 if (S.CurrentInstantiationScope) {
644 // If the template argument pack was explicitly specified, add that to
645 // the set of deduced arguments.
646 const TemplateArgument *ExplicitArgs;
647 unsigned NumExplicitArgs;
648 NamedDecl *PartiallySubstitutedPack =
649 S.CurrentInstantiationScope->getPartiallySubstitutedPack(
650 &ExplicitArgs, &NumExplicitArgs);
651 if (PartiallySubstitutedPack &&
652 getDepthAndIndex(PartiallySubstitutedPack).second == Pack.Index)
653 Pack.New.append(ExplicitArgs, ExplicitArgs + NumExplicitArgs);
658 ~PackDeductionScope() {
659 for (auto &Pack : Packs)
660 Info.PendingDeducedPacks[Pack.Index] = Pack.Outer;
663 /// Move to deducing the next element in each pack that is being deduced.
664 void nextPackElement() {
665 // Capture the deduced template arguments for each parameter pack expanded
666 // by this pack expansion, add them to the list of arguments we've deduced
667 // for that pack, then clear out the deduced argument.
668 for (auto &Pack : Packs) {
669 DeducedTemplateArgument &DeducedArg = Deduced[Pack.Index];
670 if (!DeducedArg.isNull()) {
671 Pack.New.push_back(DeducedArg);
672 DeducedArg = DeducedTemplateArgument();
677 /// \brief Finish template argument deduction for a set of argument packs,
678 /// producing the argument packs and checking for consistency with prior
680 Sema::TemplateDeductionResult finish(bool HasAnyArguments) {
681 // Build argument packs for each of the parameter packs expanded by this
683 for (auto &Pack : Packs) {
684 // Put back the old value for this pack.
685 Deduced[Pack.Index] = Pack.Saved;
687 // Build or find a new value for this pack.
688 DeducedTemplateArgument NewPack;
689 if (HasAnyArguments && Pack.New.empty()) {
690 if (Pack.DeferredDeduction.isNull()) {
691 // We were not able to deduce anything for this parameter pack
692 // (because it only appeared in non-deduced contexts), so just
693 // restore the saved argument pack.
697 NewPack = Pack.DeferredDeduction;
698 Pack.DeferredDeduction = TemplateArgument();
699 } else if (Pack.New.empty()) {
700 // If we deduced an empty argument pack, create it now.
701 NewPack = DeducedTemplateArgument(TemplateArgument::getEmptyPack());
703 TemplateArgument *ArgumentPack =
704 new (S.Context) TemplateArgument[Pack.New.size()];
705 std::copy(Pack.New.begin(), Pack.New.end(), ArgumentPack);
706 NewPack = DeducedTemplateArgument(
707 TemplateArgument(ArgumentPack, Pack.New.size()),
708 Pack.New[0].wasDeducedFromArrayBound());
711 // Pick where we're going to put the merged pack.
712 DeducedTemplateArgument *Loc;
714 if (Pack.Outer->DeferredDeduction.isNull()) {
715 // Defer checking this pack until we have a complete pack to compare
717 Pack.Outer->DeferredDeduction = NewPack;
720 Loc = &Pack.Outer->DeferredDeduction;
722 Loc = &Deduced[Pack.Index];
725 // Check the new pack matches any previous value.
726 DeducedTemplateArgument OldPack = *Loc;
727 DeducedTemplateArgument Result =
728 checkDeducedTemplateArguments(S.Context, OldPack, NewPack);
730 // If we deferred a deduction of this pack, check that one now too.
731 if (!Result.isNull() && !Pack.DeferredDeduction.isNull()) {
733 NewPack = Pack.DeferredDeduction;
734 Result = checkDeducedTemplateArguments(S.Context, OldPack, NewPack);
737 if (Result.isNull()) {
739 makeTemplateParameter(TemplateParams->getParam(Pack.Index));
740 Info.FirstArg = OldPack;
741 Info.SecondArg = NewPack;
742 return Sema::TDK_Inconsistent;
748 return Sema::TDK_Success;
753 TemplateParameterList *TemplateParams;
754 SmallVectorImpl<DeducedTemplateArgument> &Deduced;
755 TemplateDeductionInfo &Info;
757 SmallVector<DeducedPack, 2> Packs;
760 /// \brief Deduce the template arguments by comparing the list of parameter
761 /// types to the list of argument types, as in the parameter-type-lists of
762 /// function types (C++ [temp.deduct.type]p10).
764 /// \param S The semantic analysis object within which we are deducing
766 /// \param TemplateParams The template parameters that we are deducing
768 /// \param Params The list of parameter types
770 /// \param NumParams The number of types in \c Params
772 /// \param Args The list of argument types
774 /// \param NumArgs The number of types in \c Args
776 /// \param Info information about the template argument deduction itself
778 /// \param Deduced the deduced template arguments
780 /// \param TDF bitwise OR of the TemplateDeductionFlags bits that describe
781 /// how template argument deduction is performed.
783 /// \param PartialOrdering If true, we are performing template argument
784 /// deduction for during partial ordering for a call
785 /// (C++0x [temp.deduct.partial]).
787 /// \param RefParamComparisons If we're performing template argument deduction
788 /// in the context of partial ordering, the set of qualifier comparisons.
790 /// \returns the result of template argument deduction so far. Note that a
791 /// "success" result means that template argument deduction has not yet failed,
792 /// but it may still fail, later, for other reasons.
793 static Sema::TemplateDeductionResult
794 DeduceTemplateArguments(Sema &S,
795 TemplateParameterList *TemplateParams,
796 const QualType *Params, unsigned NumParams,
797 const QualType *Args, unsigned NumArgs,
798 TemplateDeductionInfo &Info,
799 SmallVectorImpl<DeducedTemplateArgument> &Deduced,
801 bool PartialOrdering = false,
802 SmallVectorImpl<RefParamPartialOrderingComparison> *
803 RefParamComparisons = nullptr) {
804 // Fast-path check to see if we have too many/too few arguments.
805 if (NumParams != NumArgs &&
806 !(NumParams && isa<PackExpansionType>(Params[NumParams - 1])) &&
807 !(NumArgs && isa<PackExpansionType>(Args[NumArgs - 1])))
808 return Sema::TDK_MiscellaneousDeductionFailure;
810 // C++0x [temp.deduct.type]p10:
811 // Similarly, if P has a form that contains (T), then each parameter type
812 // Pi of the respective parameter-type- list of P is compared with the
813 // corresponding parameter type Ai of the corresponding parameter-type-list
815 unsigned ArgIdx = 0, ParamIdx = 0;
816 for (; ParamIdx != NumParams; ++ParamIdx) {
817 // Check argument types.
818 const PackExpansionType *Expansion
819 = dyn_cast<PackExpansionType>(Params[ParamIdx]);
821 // Simple case: compare the parameter and argument types at this point.
823 // Make sure we have an argument.
824 if (ArgIdx >= NumArgs)
825 return Sema::TDK_MiscellaneousDeductionFailure;
827 if (isa<PackExpansionType>(Args[ArgIdx])) {
828 // C++0x [temp.deduct.type]p22:
829 // If the original function parameter associated with A is a function
830 // parameter pack and the function parameter associated with P is not
831 // a function parameter pack, then template argument deduction fails.
832 return Sema::TDK_MiscellaneousDeductionFailure;
835 if (Sema::TemplateDeductionResult Result
836 = DeduceTemplateArgumentsByTypeMatch(S, TemplateParams,
837 Params[ParamIdx], Args[ArgIdx],
840 RefParamComparisons))
847 // C++0x [temp.deduct.type]p5:
848 // The non-deduced contexts are:
849 // - A function parameter pack that does not occur at the end of the
850 // parameter-declaration-clause.
851 if (ParamIdx + 1 < NumParams)
852 return Sema::TDK_Success;
854 // C++0x [temp.deduct.type]p10:
855 // If the parameter-declaration corresponding to Pi is a function
856 // parameter pack, then the type of its declarator- id is compared with
857 // each remaining parameter type in the parameter-type-list of A. Each
858 // comparison deduces template arguments for subsequent positions in the
859 // template parameter packs expanded by the function parameter pack.
861 QualType Pattern = Expansion->getPattern();
862 PackDeductionScope PackScope(S, TemplateParams, Deduced, Info, Pattern);
864 bool HasAnyArguments = false;
865 for (; ArgIdx < NumArgs; ++ArgIdx) {
866 HasAnyArguments = true;
868 // Deduce template arguments from the pattern.
869 if (Sema::TemplateDeductionResult Result
870 = DeduceTemplateArgumentsByTypeMatch(S, TemplateParams, Pattern,
871 Args[ArgIdx], Info, Deduced,
872 TDF, PartialOrdering,
873 RefParamComparisons))
876 PackScope.nextPackElement();
879 // Build argument packs for each of the parameter packs expanded by this
881 if (auto Result = PackScope.finish(HasAnyArguments))
885 // Make sure we don't have any extra arguments.
886 if (ArgIdx < NumArgs)
887 return Sema::TDK_MiscellaneousDeductionFailure;
889 return Sema::TDK_Success;
892 /// \brief Determine whether the parameter has qualifiers that are either
893 /// inconsistent with or a superset of the argument's qualifiers.
894 static bool hasInconsistentOrSupersetQualifiersOf(QualType ParamType,
896 Qualifiers ParamQs = ParamType.getQualifiers();
897 Qualifiers ArgQs = ArgType.getQualifiers();
899 if (ParamQs == ArgQs)
902 // Mismatched (but not missing) Objective-C GC attributes.
903 if (ParamQs.getObjCGCAttr() != ArgQs.getObjCGCAttr() &&
904 ParamQs.hasObjCGCAttr())
907 // Mismatched (but not missing) address spaces.
908 if (ParamQs.getAddressSpace() != ArgQs.getAddressSpace() &&
909 ParamQs.hasAddressSpace())
912 // Mismatched (but not missing) Objective-C lifetime qualifiers.
913 if (ParamQs.getObjCLifetime() != ArgQs.getObjCLifetime() &&
914 ParamQs.hasObjCLifetime())
917 // CVR qualifier superset.
918 return (ParamQs.getCVRQualifiers() != ArgQs.getCVRQualifiers()) &&
919 ((ParamQs.getCVRQualifiers() | ArgQs.getCVRQualifiers())
920 == ParamQs.getCVRQualifiers());
923 /// \brief Compare types for equality with respect to possibly compatible
924 /// function types (noreturn adjustment, implicit calling conventions). If any
925 /// of parameter and argument is not a function, just perform type comparison.
927 /// \param Param the template parameter type.
929 /// \param Arg the argument type.
930 bool Sema::isSameOrCompatibleFunctionType(CanQualType Param,
932 const FunctionType *ParamFunction = Param->getAs<FunctionType>(),
933 *ArgFunction = Arg->getAs<FunctionType>();
935 // Just compare if not functions.
936 if (!ParamFunction || !ArgFunction)
939 // Noreturn adjustment.
940 QualType AdjustedParam;
941 if (IsNoReturnConversion(Param, Arg, AdjustedParam))
942 return Arg == Context.getCanonicalType(AdjustedParam);
944 // FIXME: Compatible calling conventions.
949 /// \brief Deduce the template arguments by comparing the parameter type and
950 /// the argument type (C++ [temp.deduct.type]).
952 /// \param S the semantic analysis object within which we are deducing
954 /// \param TemplateParams the template parameters that we are deducing
956 /// \param ParamIn the parameter type
958 /// \param ArgIn the argument type
960 /// \param Info information about the template argument deduction itself
962 /// \param Deduced the deduced template arguments
964 /// \param TDF bitwise OR of the TemplateDeductionFlags bits that describe
965 /// how template argument deduction is performed.
967 /// \param PartialOrdering Whether we're performing template argument deduction
968 /// in the context of partial ordering (C++0x [temp.deduct.partial]).
970 /// \param RefParamComparisons If we're performing template argument deduction
971 /// in the context of partial ordering, the set of qualifier comparisons.
973 /// \returns the result of template argument deduction so far. Note that a
974 /// "success" result means that template argument deduction has not yet failed,
975 /// but it may still fail, later, for other reasons.
976 static Sema::TemplateDeductionResult
977 DeduceTemplateArgumentsByTypeMatch(Sema &S,
978 TemplateParameterList *TemplateParams,
979 QualType ParamIn, QualType ArgIn,
980 TemplateDeductionInfo &Info,
981 SmallVectorImpl<DeducedTemplateArgument> &Deduced,
983 bool PartialOrdering,
984 SmallVectorImpl<RefParamPartialOrderingComparison> *
985 RefParamComparisons) {
986 // We only want to look at the canonical types, since typedefs and
987 // sugar are not part of template argument deduction.
988 QualType Param = S.Context.getCanonicalType(ParamIn);
989 QualType Arg = S.Context.getCanonicalType(ArgIn);
991 // If the argument type is a pack expansion, look at its pattern.
992 // This isn't explicitly called out
993 if (const PackExpansionType *ArgExpansion
994 = dyn_cast<PackExpansionType>(Arg))
995 Arg = ArgExpansion->getPattern();
997 if (PartialOrdering) {
998 // C++0x [temp.deduct.partial]p5:
999 // Before the partial ordering is done, certain transformations are
1000 // performed on the types used for partial ordering:
1001 // - If P is a reference type, P is replaced by the type referred to.
1002 const ReferenceType *ParamRef = Param->getAs<ReferenceType>();
1004 Param = ParamRef->getPointeeType();
1006 // - If A is a reference type, A is replaced by the type referred to.
1007 const ReferenceType *ArgRef = Arg->getAs<ReferenceType>();
1009 Arg = ArgRef->getPointeeType();
1011 if (RefParamComparisons && ParamRef && ArgRef) {
1012 // C++0x [temp.deduct.partial]p6:
1013 // If both P and A were reference types (before being replaced with the
1014 // type referred to above), determine which of the two types (if any) is
1015 // more cv-qualified than the other; otherwise the types are considered
1016 // to be equally cv-qualified for partial ordering purposes. The result
1017 // of this determination will be used below.
1019 // We save this information for later, using it only when deduction
1020 // succeeds in both directions.
1021 RefParamPartialOrderingComparison Comparison;
1022 Comparison.ParamIsRvalueRef = ParamRef->getAs<RValueReferenceType>();
1023 Comparison.ArgIsRvalueRef = ArgRef->getAs<RValueReferenceType>();
1024 Comparison.Qualifiers = NeitherMoreQualified;
1026 Qualifiers ParamQuals = Param.getQualifiers();
1027 Qualifiers ArgQuals = Arg.getQualifiers();
1028 if (ParamQuals.isStrictSupersetOf(ArgQuals))
1029 Comparison.Qualifiers = ParamMoreQualified;
1030 else if (ArgQuals.isStrictSupersetOf(ParamQuals))
1031 Comparison.Qualifiers = ArgMoreQualified;
1032 else if (ArgQuals.getObjCLifetime() != ParamQuals.getObjCLifetime() &&
1033 ArgQuals.withoutObjCLifetime()
1034 == ParamQuals.withoutObjCLifetime()) {
1035 // Prefer binding to non-__unsafe_autoretained parameters.
1036 if (ArgQuals.getObjCLifetime() == Qualifiers::OCL_ExplicitNone &&
1037 ParamQuals.getObjCLifetime())
1038 Comparison.Qualifiers = ParamMoreQualified;
1039 else if (ParamQuals.getObjCLifetime() == Qualifiers::OCL_ExplicitNone &&
1040 ArgQuals.getObjCLifetime())
1041 Comparison.Qualifiers = ArgMoreQualified;
1043 RefParamComparisons->push_back(Comparison);
1046 // C++0x [temp.deduct.partial]p7:
1047 // Remove any top-level cv-qualifiers:
1048 // - If P is a cv-qualified type, P is replaced by the cv-unqualified
1050 Param = Param.getUnqualifiedType();
1051 // - If A is a cv-qualified type, A is replaced by the cv-unqualified
1053 Arg = Arg.getUnqualifiedType();
1055 // C++0x [temp.deduct.call]p4 bullet 1:
1056 // - If the original P is a reference type, the deduced A (i.e., the type
1057 // referred to by the reference) can be more cv-qualified than the
1059 if (TDF & TDF_ParamWithReferenceType) {
1061 QualType UnqualParam = S.Context.getUnqualifiedArrayType(Param, Quals);
1062 Quals.setCVRQualifiers(Quals.getCVRQualifiers() &
1063 Arg.getCVRQualifiers());
1064 Param = S.Context.getQualifiedType(UnqualParam, Quals);
1067 if ((TDF & TDF_TopLevelParameterTypeList) && !Param->isFunctionType()) {
1068 // C++0x [temp.deduct.type]p10:
1069 // If P and A are function types that originated from deduction when
1070 // taking the address of a function template (14.8.2.2) or when deducing
1071 // template arguments from a function declaration (14.8.2.6) and Pi and
1072 // Ai are parameters of the top-level parameter-type-list of P and A,
1073 // respectively, Pi is adjusted if it is an rvalue reference to a
1074 // cv-unqualified template parameter and Ai is an lvalue reference, in
1075 // which case the type of Pi is changed to be the template parameter
1076 // type (i.e., T&& is changed to simply T). [ Note: As a result, when
1077 // Pi is T&& and Ai is X&, the adjusted Pi will be T, causing T to be
1078 // deduced as X&. - end note ]
1079 TDF &= ~TDF_TopLevelParameterTypeList;
1081 if (const RValueReferenceType *ParamRef
1082 = Param->getAs<RValueReferenceType>()) {
1083 if (isa<TemplateTypeParmType>(ParamRef->getPointeeType()) &&
1084 !ParamRef->getPointeeType().getQualifiers())
1085 if (Arg->isLValueReferenceType())
1086 Param = ParamRef->getPointeeType();
1091 // C++ [temp.deduct.type]p9:
1092 // A template type argument T, a template template argument TT or a
1093 // template non-type argument i can be deduced if P and A have one of
1094 // the following forms:
1098 if (const TemplateTypeParmType *TemplateTypeParm
1099 = Param->getAs<TemplateTypeParmType>()) {
1100 // Just skip any attempts to deduce from a placeholder type.
1101 if (Arg->isPlaceholderType())
1102 return Sema::TDK_Success;
1104 unsigned Index = TemplateTypeParm->getIndex();
1105 bool RecanonicalizeArg = false;
1107 // If the argument type is an array type, move the qualifiers up to the
1108 // top level, so they can be matched with the qualifiers on the parameter.
1109 if (isa<ArrayType>(Arg)) {
1111 Arg = S.Context.getUnqualifiedArrayType(Arg, Quals);
1113 Arg = S.Context.getQualifiedType(Arg, Quals);
1114 RecanonicalizeArg = true;
1118 // The argument type can not be less qualified than the parameter
1120 if (!(TDF & TDF_IgnoreQualifiers) &&
1121 hasInconsistentOrSupersetQualifiersOf(Param, Arg)) {
1122 Info.Param = cast<TemplateTypeParmDecl>(TemplateParams->getParam(Index));
1123 Info.FirstArg = TemplateArgument(Param);
1124 Info.SecondArg = TemplateArgument(Arg);
1125 return Sema::TDK_Underqualified;
1128 assert(TemplateTypeParm->getDepth() == 0 && "Can't deduce with depth > 0");
1129 assert(Arg != S.Context.OverloadTy && "Unresolved overloaded function");
1130 QualType DeducedType = Arg;
1132 // Remove any qualifiers on the parameter from the deduced type.
1133 // We checked the qualifiers for consistency above.
1134 Qualifiers DeducedQs = DeducedType.getQualifiers();
1135 Qualifiers ParamQs = Param.getQualifiers();
1136 DeducedQs.removeCVRQualifiers(ParamQs.getCVRQualifiers());
1137 if (ParamQs.hasObjCGCAttr())
1138 DeducedQs.removeObjCGCAttr();
1139 if (ParamQs.hasAddressSpace())
1140 DeducedQs.removeAddressSpace();
1141 if (ParamQs.hasObjCLifetime())
1142 DeducedQs.removeObjCLifetime();
1145 // If template deduction would produce a lifetime qualifier on a type
1146 // that is not a lifetime type, template argument deduction fails.
1147 if (ParamQs.hasObjCLifetime() && !DeducedType->isObjCLifetimeType() &&
1148 !DeducedType->isDependentType()) {
1149 Info.Param = cast<TemplateTypeParmDecl>(TemplateParams->getParam(Index));
1150 Info.FirstArg = TemplateArgument(Param);
1151 Info.SecondArg = TemplateArgument(Arg);
1152 return Sema::TDK_Underqualified;
1156 // If template deduction would produce an argument type with lifetime type
1157 // but no lifetime qualifier, the __strong lifetime qualifier is inferred.
1158 if (S.getLangOpts().ObjCAutoRefCount &&
1159 DeducedType->isObjCLifetimeType() &&
1160 !DeducedQs.hasObjCLifetime())
1161 DeducedQs.setObjCLifetime(Qualifiers::OCL_Strong);
1163 DeducedType = S.Context.getQualifiedType(DeducedType.getUnqualifiedType(),
1166 if (RecanonicalizeArg)
1167 DeducedType = S.Context.getCanonicalType(DeducedType);
1169 DeducedTemplateArgument NewDeduced(DeducedType);
1170 DeducedTemplateArgument Result = checkDeducedTemplateArguments(S.Context,
1173 if (Result.isNull()) {
1174 Info.Param = cast<TemplateTypeParmDecl>(TemplateParams->getParam(Index));
1175 Info.FirstArg = Deduced[Index];
1176 Info.SecondArg = NewDeduced;
1177 return Sema::TDK_Inconsistent;
1180 Deduced[Index] = Result;
1181 return Sema::TDK_Success;
1184 // Set up the template argument deduction information for a failure.
1185 Info.FirstArg = TemplateArgument(ParamIn);
1186 Info.SecondArg = TemplateArgument(ArgIn);
1188 // If the parameter is an already-substituted template parameter
1189 // pack, do nothing: we don't know which of its arguments to look
1190 // at, so we have to wait until all of the parameter packs in this
1191 // expansion have arguments.
1192 if (isa<SubstTemplateTypeParmPackType>(Param))
1193 return Sema::TDK_Success;
1195 // Check the cv-qualifiers on the parameter and argument types.
1196 CanQualType CanParam = S.Context.getCanonicalType(Param);
1197 CanQualType CanArg = S.Context.getCanonicalType(Arg);
1198 if (!(TDF & TDF_IgnoreQualifiers)) {
1199 if (TDF & TDF_ParamWithReferenceType) {
1200 if (hasInconsistentOrSupersetQualifiersOf(Param, Arg))
1201 return Sema::TDK_NonDeducedMismatch;
1202 } else if (!IsPossiblyOpaquelyQualifiedType(Param)) {
1203 if (Param.getCVRQualifiers() != Arg.getCVRQualifiers())
1204 return Sema::TDK_NonDeducedMismatch;
1207 // If the parameter type is not dependent, there is nothing to deduce.
1208 if (!Param->isDependentType()) {
1209 if (!(TDF & TDF_SkipNonDependent)) {
1210 bool NonDeduced = (TDF & TDF_InOverloadResolution)?
1211 !S.isSameOrCompatibleFunctionType(CanParam, CanArg) :
1214 return Sema::TDK_NonDeducedMismatch;
1217 return Sema::TDK_Success;
1219 } else if (!Param->isDependentType()) {
1220 CanQualType ParamUnqualType = CanParam.getUnqualifiedType(),
1221 ArgUnqualType = CanArg.getUnqualifiedType();
1222 bool Success = (TDF & TDF_InOverloadResolution)?
1223 S.isSameOrCompatibleFunctionType(ParamUnqualType,
1225 ParamUnqualType == ArgUnqualType;
1227 return Sema::TDK_Success;
1230 switch (Param->getTypeClass()) {
1231 // Non-canonical types cannot appear here.
1232 #define NON_CANONICAL_TYPE(Class, Base) \
1233 case Type::Class: llvm_unreachable("deducing non-canonical type: " #Class);
1234 #define TYPE(Class, Base)
1235 #include "clang/AST/TypeNodes.def"
1237 case Type::TemplateTypeParm:
1238 case Type::SubstTemplateTypeParmPack:
1239 llvm_unreachable("Type nodes handled above");
1241 // These types cannot be dependent, so simply check whether the types are
1244 case Type::VariableArray:
1246 case Type::FunctionNoProto:
1249 case Type::ObjCObject:
1250 case Type::ObjCInterface:
1251 case Type::ObjCObjectPointer: {
1252 if (TDF & TDF_SkipNonDependent)
1253 return Sema::TDK_Success;
1255 if (TDF & TDF_IgnoreQualifiers) {
1256 Param = Param.getUnqualifiedType();
1257 Arg = Arg.getUnqualifiedType();
1260 return Param == Arg? Sema::TDK_Success : Sema::TDK_NonDeducedMismatch;
1263 // _Complex T [placeholder extension]
1265 if (const ComplexType *ComplexArg = Arg->getAs<ComplexType>())
1266 return DeduceTemplateArgumentsByTypeMatch(S, TemplateParams,
1267 cast<ComplexType>(Param)->getElementType(),
1268 ComplexArg->getElementType(),
1269 Info, Deduced, TDF);
1271 return Sema::TDK_NonDeducedMismatch;
1273 // _Atomic T [extension]
1275 if (const AtomicType *AtomicArg = Arg->getAs<AtomicType>())
1276 return DeduceTemplateArgumentsByTypeMatch(S, TemplateParams,
1277 cast<AtomicType>(Param)->getValueType(),
1278 AtomicArg->getValueType(),
1279 Info, Deduced, TDF);
1281 return Sema::TDK_NonDeducedMismatch;
1284 case Type::Pointer: {
1285 QualType PointeeType;
1286 if (const PointerType *PointerArg = Arg->getAs<PointerType>()) {
1287 PointeeType = PointerArg->getPointeeType();
1288 } else if (const ObjCObjectPointerType *PointerArg
1289 = Arg->getAs<ObjCObjectPointerType>()) {
1290 PointeeType = PointerArg->getPointeeType();
1292 return Sema::TDK_NonDeducedMismatch;
1295 unsigned SubTDF = TDF & (TDF_IgnoreQualifiers | TDF_DerivedClass);
1296 return DeduceTemplateArgumentsByTypeMatch(S, TemplateParams,
1297 cast<PointerType>(Param)->getPointeeType(),
1299 Info, Deduced, SubTDF);
1303 case Type::LValueReference: {
1304 const LValueReferenceType *ReferenceArg =
1305 Arg->getAs<LValueReferenceType>();
1307 return Sema::TDK_NonDeducedMismatch;
1309 return DeduceTemplateArgumentsByTypeMatch(S, TemplateParams,
1310 cast<LValueReferenceType>(Param)->getPointeeType(),
1311 ReferenceArg->getPointeeType(), Info, Deduced, 0);
1315 case Type::RValueReference: {
1316 const RValueReferenceType *ReferenceArg =
1317 Arg->getAs<RValueReferenceType>();
1319 return Sema::TDK_NonDeducedMismatch;
1321 return DeduceTemplateArgumentsByTypeMatch(S, TemplateParams,
1322 cast<RValueReferenceType>(Param)->getPointeeType(),
1323 ReferenceArg->getPointeeType(),
1327 // T [] (implied, but not stated explicitly)
1328 case Type::IncompleteArray: {
1329 const IncompleteArrayType *IncompleteArrayArg =
1330 S.Context.getAsIncompleteArrayType(Arg);
1331 if (!IncompleteArrayArg)
1332 return Sema::TDK_NonDeducedMismatch;
1334 unsigned SubTDF = TDF & TDF_IgnoreQualifiers;
1335 return DeduceTemplateArgumentsByTypeMatch(S, TemplateParams,
1336 S.Context.getAsIncompleteArrayType(Param)->getElementType(),
1337 IncompleteArrayArg->getElementType(),
1338 Info, Deduced, SubTDF);
1341 // T [integer-constant]
1342 case Type::ConstantArray: {
1343 const ConstantArrayType *ConstantArrayArg =
1344 S.Context.getAsConstantArrayType(Arg);
1345 if (!ConstantArrayArg)
1346 return Sema::TDK_NonDeducedMismatch;
1348 const ConstantArrayType *ConstantArrayParm =
1349 S.Context.getAsConstantArrayType(Param);
1350 if (ConstantArrayArg->getSize() != ConstantArrayParm->getSize())
1351 return Sema::TDK_NonDeducedMismatch;
1353 unsigned SubTDF = TDF & TDF_IgnoreQualifiers;
1354 return DeduceTemplateArgumentsByTypeMatch(S, TemplateParams,
1355 ConstantArrayParm->getElementType(),
1356 ConstantArrayArg->getElementType(),
1357 Info, Deduced, SubTDF);
1361 case Type::DependentSizedArray: {
1362 const ArrayType *ArrayArg = S.Context.getAsArrayType(Arg);
1364 return Sema::TDK_NonDeducedMismatch;
1366 unsigned SubTDF = TDF & TDF_IgnoreQualifiers;
1368 // Check the element type of the arrays
1369 const DependentSizedArrayType *DependentArrayParm
1370 = S.Context.getAsDependentSizedArrayType(Param);
1371 if (Sema::TemplateDeductionResult Result
1372 = DeduceTemplateArgumentsByTypeMatch(S, TemplateParams,
1373 DependentArrayParm->getElementType(),
1374 ArrayArg->getElementType(),
1375 Info, Deduced, SubTDF))
1378 // Determine the array bound is something we can deduce.
1379 NonTypeTemplateParmDecl *NTTP
1380 = getDeducedParameterFromExpr(DependentArrayParm->getSizeExpr());
1382 return Sema::TDK_Success;
1384 // We can perform template argument deduction for the given non-type
1385 // template parameter.
1386 assert(NTTP->getDepth() == 0 &&
1387 "Cannot deduce non-type template argument at depth > 0");
1388 if (const ConstantArrayType *ConstantArrayArg
1389 = dyn_cast<ConstantArrayType>(ArrayArg)) {
1390 llvm::APSInt Size(ConstantArrayArg->getSize());
1391 return DeduceNonTypeTemplateArgument(S, NTTP, Size,
1392 S.Context.getSizeType(),
1393 /*ArrayBound=*/true,
1396 if (const DependentSizedArrayType *DependentArrayArg
1397 = dyn_cast<DependentSizedArrayType>(ArrayArg))
1398 if (DependentArrayArg->getSizeExpr())
1399 return DeduceNonTypeTemplateArgument(S, NTTP,
1400 DependentArrayArg->getSizeExpr(),
1403 // Incomplete type does not match a dependently-sized array type
1404 return Sema::TDK_NonDeducedMismatch;
1410 case Type::FunctionProto: {
1411 unsigned SubTDF = TDF & TDF_TopLevelParameterTypeList;
1412 const FunctionProtoType *FunctionProtoArg =
1413 dyn_cast<FunctionProtoType>(Arg);
1414 if (!FunctionProtoArg)
1415 return Sema::TDK_NonDeducedMismatch;
1417 const FunctionProtoType *FunctionProtoParam =
1418 cast<FunctionProtoType>(Param);
1420 if (FunctionProtoParam->getTypeQuals()
1421 != FunctionProtoArg->getTypeQuals() ||
1422 FunctionProtoParam->getRefQualifier()
1423 != FunctionProtoArg->getRefQualifier() ||
1424 FunctionProtoParam->isVariadic() != FunctionProtoArg->isVariadic())
1425 return Sema::TDK_NonDeducedMismatch;
1427 // Check return types.
1428 if (Sema::TemplateDeductionResult Result =
1429 DeduceTemplateArgumentsByTypeMatch(
1430 S, TemplateParams, FunctionProtoParam->getReturnType(),
1431 FunctionProtoArg->getReturnType(), Info, Deduced, 0))
1434 return DeduceTemplateArguments(
1435 S, TemplateParams, FunctionProtoParam->param_type_begin(),
1436 FunctionProtoParam->getNumParams(),
1437 FunctionProtoArg->param_type_begin(),
1438 FunctionProtoArg->getNumParams(), Info, Deduced, SubTDF);
1441 case Type::InjectedClassName: {
1442 // Treat a template's injected-class-name as if the template
1443 // specialization type had been used.
1444 Param = cast<InjectedClassNameType>(Param)
1445 ->getInjectedSpecializationType();
1446 assert(isa<TemplateSpecializationType>(Param) &&
1447 "injected class name is not a template specialization type");
1451 // template-name<T> (where template-name refers to a class template)
1456 case Type::TemplateSpecialization: {
1457 const TemplateSpecializationType *SpecParam
1458 = cast<TemplateSpecializationType>(Param);
1460 // Try to deduce template arguments from the template-id.
1461 Sema::TemplateDeductionResult Result
1462 = DeduceTemplateArguments(S, TemplateParams, SpecParam, Arg,
1465 if (Result && (TDF & TDF_DerivedClass)) {
1466 // C++ [temp.deduct.call]p3b3:
1467 // If P is a class, and P has the form template-id, then A can be a
1468 // derived class of the deduced A. Likewise, if P is a pointer to a
1469 // class of the form template-id, A can be a pointer to a derived
1470 // class pointed to by the deduced A.
1472 // More importantly:
1473 // These alternatives are considered only if type deduction would
1475 if (const RecordType *RecordT = Arg->getAs<RecordType>()) {
1476 // We cannot inspect base classes as part of deduction when the type
1477 // is incomplete, so either instantiate any templates necessary to
1478 // complete the type, or skip over it if it cannot be completed.
1479 if (S.RequireCompleteType(Info.getLocation(), Arg, 0))
1482 // Use data recursion to crawl through the list of base classes.
1483 // Visited contains the set of nodes we have already visited, while
1484 // ToVisit is our stack of records that we still need to visit.
1485 llvm::SmallPtrSet<const RecordType *, 8> Visited;
1486 SmallVector<const RecordType *, 8> ToVisit;
1487 ToVisit.push_back(RecordT);
1488 bool Successful = false;
1489 SmallVector<DeducedTemplateArgument, 8> DeducedOrig(Deduced.begin(),
1491 while (!ToVisit.empty()) {
1492 // Retrieve the next class in the inheritance hierarchy.
1493 const RecordType *NextT = ToVisit.pop_back_val();
1495 // If we have already seen this type, skip it.
1496 if (!Visited.insert(NextT).second)
1499 // If this is a base class, try to perform template argument
1500 // deduction from it.
1501 if (NextT != RecordT) {
1502 TemplateDeductionInfo BaseInfo(Info.getLocation());
1503 Sema::TemplateDeductionResult BaseResult
1504 = DeduceTemplateArguments(S, TemplateParams, SpecParam,
1505 QualType(NextT, 0), BaseInfo,
1508 // If template argument deduction for this base was successful,
1509 // note that we had some success. Otherwise, ignore any deductions
1510 // from this base class.
1511 if (BaseResult == Sema::TDK_Success) {
1513 DeducedOrig.clear();
1514 DeducedOrig.append(Deduced.begin(), Deduced.end());
1515 Info.Param = BaseInfo.Param;
1516 Info.FirstArg = BaseInfo.FirstArg;
1517 Info.SecondArg = BaseInfo.SecondArg;
1520 Deduced = DeducedOrig;
1523 // Visit base classes
1524 CXXRecordDecl *Next = cast<CXXRecordDecl>(NextT->getDecl());
1525 for (const auto &Base : Next->bases()) {
1526 assert(Base.getType()->isRecordType() &&
1527 "Base class that isn't a record?");
1528 ToVisit.push_back(Base.getType()->getAs<RecordType>());
1533 return Sema::TDK_Success;
1545 // type (type::*)(T)
1550 case Type::MemberPointer: {
1551 const MemberPointerType *MemPtrParam = cast<MemberPointerType>(Param);
1552 const MemberPointerType *MemPtrArg = dyn_cast<MemberPointerType>(Arg);
1554 return Sema::TDK_NonDeducedMismatch;
1556 if (Sema::TemplateDeductionResult Result
1557 = DeduceTemplateArgumentsByTypeMatch(S, TemplateParams,
1558 MemPtrParam->getPointeeType(),
1559 MemPtrArg->getPointeeType(),
1561 TDF & TDF_IgnoreQualifiers))
1564 return DeduceTemplateArgumentsByTypeMatch(S, TemplateParams,
1565 QualType(MemPtrParam->getClass(), 0),
1566 QualType(MemPtrArg->getClass(), 0),
1568 TDF & TDF_IgnoreQualifiers);
1571 // (clang extension)
1576 case Type::BlockPointer: {
1577 const BlockPointerType *BlockPtrParam = cast<BlockPointerType>(Param);
1578 const BlockPointerType *BlockPtrArg = dyn_cast<BlockPointerType>(Arg);
1581 return Sema::TDK_NonDeducedMismatch;
1583 return DeduceTemplateArgumentsByTypeMatch(S, TemplateParams,
1584 BlockPtrParam->getPointeeType(),
1585 BlockPtrArg->getPointeeType(),
1589 // (clang extension)
1591 // T __attribute__(((ext_vector_type(<integral constant>))))
1592 case Type::ExtVector: {
1593 const ExtVectorType *VectorParam = cast<ExtVectorType>(Param);
1594 if (const ExtVectorType *VectorArg = dyn_cast<ExtVectorType>(Arg)) {
1595 // Make sure that the vectors have the same number of elements.
1596 if (VectorParam->getNumElements() != VectorArg->getNumElements())
1597 return Sema::TDK_NonDeducedMismatch;
1599 // Perform deduction on the element types.
1600 return DeduceTemplateArgumentsByTypeMatch(S, TemplateParams,
1601 VectorParam->getElementType(),
1602 VectorArg->getElementType(),
1603 Info, Deduced, TDF);
1606 if (const DependentSizedExtVectorType *VectorArg
1607 = dyn_cast<DependentSizedExtVectorType>(Arg)) {
1608 // We can't check the number of elements, since the argument has a
1609 // dependent number of elements. This can only occur during partial
1612 // Perform deduction on the element types.
1613 return DeduceTemplateArgumentsByTypeMatch(S, TemplateParams,
1614 VectorParam->getElementType(),
1615 VectorArg->getElementType(),
1616 Info, Deduced, TDF);
1619 return Sema::TDK_NonDeducedMismatch;
1622 // (clang extension)
1624 // T __attribute__(((ext_vector_type(N))))
1625 case Type::DependentSizedExtVector: {
1626 const DependentSizedExtVectorType *VectorParam
1627 = cast<DependentSizedExtVectorType>(Param);
1629 if (const ExtVectorType *VectorArg = dyn_cast<ExtVectorType>(Arg)) {
1630 // Perform deduction on the element types.
1631 if (Sema::TemplateDeductionResult Result
1632 = DeduceTemplateArgumentsByTypeMatch(S, TemplateParams,
1633 VectorParam->getElementType(),
1634 VectorArg->getElementType(),
1635 Info, Deduced, TDF))
1638 // Perform deduction on the vector size, if we can.
1639 NonTypeTemplateParmDecl *NTTP
1640 = getDeducedParameterFromExpr(VectorParam->getSizeExpr());
1642 return Sema::TDK_Success;
1644 llvm::APSInt ArgSize(S.Context.getTypeSize(S.Context.IntTy), false);
1645 ArgSize = VectorArg->getNumElements();
1646 return DeduceNonTypeTemplateArgument(S, NTTP, ArgSize, S.Context.IntTy,
1647 false, Info, Deduced);
1650 if (const DependentSizedExtVectorType *VectorArg
1651 = dyn_cast<DependentSizedExtVectorType>(Arg)) {
1652 // Perform deduction on the element types.
1653 if (Sema::TemplateDeductionResult Result
1654 = DeduceTemplateArgumentsByTypeMatch(S, TemplateParams,
1655 VectorParam->getElementType(),
1656 VectorArg->getElementType(),
1657 Info, Deduced, TDF))
1660 // Perform deduction on the vector size, if we can.
1661 NonTypeTemplateParmDecl *NTTP
1662 = getDeducedParameterFromExpr(VectorParam->getSizeExpr());
1664 return Sema::TDK_Success;
1666 return DeduceNonTypeTemplateArgument(S, NTTP, VectorArg->getSizeExpr(),
1670 return Sema::TDK_NonDeducedMismatch;
1673 case Type::TypeOfExpr:
1675 case Type::DependentName:
1676 case Type::UnresolvedUsing:
1677 case Type::Decltype:
1678 case Type::UnaryTransform:
1680 case Type::DependentTemplateSpecialization:
1681 case Type::PackExpansion:
1682 // No template argument deduction for these types
1683 return Sema::TDK_Success;
1686 llvm_unreachable("Invalid Type Class!");
1689 static Sema::TemplateDeductionResult
1690 DeduceTemplateArguments(Sema &S,
1691 TemplateParameterList *TemplateParams,
1692 const TemplateArgument &Param,
1693 TemplateArgument Arg,
1694 TemplateDeductionInfo &Info,
1695 SmallVectorImpl<DeducedTemplateArgument> &Deduced) {
1696 // If the template argument is a pack expansion, perform template argument
1697 // deduction against the pattern of that expansion. This only occurs during
1698 // partial ordering.
1699 if (Arg.isPackExpansion())
1700 Arg = Arg.getPackExpansionPattern();
1702 switch (Param.getKind()) {
1703 case TemplateArgument::Null:
1704 llvm_unreachable("Null template argument in parameter list");
1706 case TemplateArgument::Type:
1707 if (Arg.getKind() == TemplateArgument::Type)
1708 return DeduceTemplateArgumentsByTypeMatch(S, TemplateParams,
1712 Info.FirstArg = Param;
1713 Info.SecondArg = Arg;
1714 return Sema::TDK_NonDeducedMismatch;
1716 case TemplateArgument::Template:
1717 if (Arg.getKind() == TemplateArgument::Template)
1718 return DeduceTemplateArguments(S, TemplateParams,
1719 Param.getAsTemplate(),
1720 Arg.getAsTemplate(), Info, Deduced);
1721 Info.FirstArg = Param;
1722 Info.SecondArg = Arg;
1723 return Sema::TDK_NonDeducedMismatch;
1725 case TemplateArgument::TemplateExpansion:
1726 llvm_unreachable("caller should handle pack expansions");
1728 case TemplateArgument::Declaration:
1729 if (Arg.getKind() == TemplateArgument::Declaration &&
1730 isSameDeclaration(Param.getAsDecl(), Arg.getAsDecl()))
1731 return Sema::TDK_Success;
1733 Info.FirstArg = Param;
1734 Info.SecondArg = Arg;
1735 return Sema::TDK_NonDeducedMismatch;
1737 case TemplateArgument::NullPtr:
1738 if (Arg.getKind() == TemplateArgument::NullPtr &&
1739 S.Context.hasSameType(Param.getNullPtrType(), Arg.getNullPtrType()))
1740 return Sema::TDK_Success;
1742 Info.FirstArg = Param;
1743 Info.SecondArg = Arg;
1744 return Sema::TDK_NonDeducedMismatch;
1746 case TemplateArgument::Integral:
1747 if (Arg.getKind() == TemplateArgument::Integral) {
1748 if (hasSameExtendedValue(Param.getAsIntegral(), Arg.getAsIntegral()))
1749 return Sema::TDK_Success;
1751 Info.FirstArg = Param;
1752 Info.SecondArg = Arg;
1753 return Sema::TDK_NonDeducedMismatch;
1756 if (Arg.getKind() == TemplateArgument::Expression) {
1757 Info.FirstArg = Param;
1758 Info.SecondArg = Arg;
1759 return Sema::TDK_NonDeducedMismatch;
1762 Info.FirstArg = Param;
1763 Info.SecondArg = Arg;
1764 return Sema::TDK_NonDeducedMismatch;
1766 case TemplateArgument::Expression: {
1767 if (NonTypeTemplateParmDecl *NTTP
1768 = getDeducedParameterFromExpr(Param.getAsExpr())) {
1769 if (Arg.getKind() == TemplateArgument::Integral)
1770 return DeduceNonTypeTemplateArgument(S, NTTP,
1771 Arg.getAsIntegral(),
1772 Arg.getIntegralType(),
1773 /*ArrayBound=*/false,
1775 if (Arg.getKind() == TemplateArgument::Expression)
1776 return DeduceNonTypeTemplateArgument(S, NTTP, Arg.getAsExpr(),
1778 if (Arg.getKind() == TemplateArgument::Declaration)
1779 return DeduceNonTypeTemplateArgument(S, NTTP, Arg.getAsDecl(),
1782 Info.FirstArg = Param;
1783 Info.SecondArg = Arg;
1784 return Sema::TDK_NonDeducedMismatch;
1787 // Can't deduce anything, but that's okay.
1788 return Sema::TDK_Success;
1790 case TemplateArgument::Pack:
1791 llvm_unreachable("Argument packs should be expanded by the caller!");
1794 llvm_unreachable("Invalid TemplateArgument Kind!");
1797 /// \brief Determine whether there is a template argument to be used for
1800 /// This routine "expands" argument packs in-place, overriding its input
1801 /// parameters so that \c Args[ArgIdx] will be the available template argument.
1803 /// \returns true if there is another template argument (which will be at
1804 /// \c Args[ArgIdx]), false otherwise.
1805 static bool hasTemplateArgumentForDeduction(const TemplateArgument *&Args,
1807 unsigned &NumArgs) {
1808 if (ArgIdx == NumArgs)
1811 const TemplateArgument &Arg = Args[ArgIdx];
1812 if (Arg.getKind() != TemplateArgument::Pack)
1815 assert(ArgIdx == NumArgs - 1 && "Pack not at the end of argument list?");
1816 Args = Arg.pack_begin();
1817 NumArgs = Arg.pack_size();
1819 return ArgIdx < NumArgs;
1822 /// \brief Determine whether the given set of template arguments has a pack
1823 /// expansion that is not the last template argument.
1824 static bool hasPackExpansionBeforeEnd(const TemplateArgument *Args,
1826 unsigned ArgIdx = 0;
1827 while (ArgIdx < NumArgs) {
1828 const TemplateArgument &Arg = Args[ArgIdx];
1830 // Unwrap argument packs.
1831 if (Args[ArgIdx].getKind() == TemplateArgument::Pack) {
1832 Args = Arg.pack_begin();
1833 NumArgs = Arg.pack_size();
1839 if (ArgIdx == NumArgs)
1842 if (Arg.isPackExpansion())
1849 static Sema::TemplateDeductionResult
1850 DeduceTemplateArguments(Sema &S,
1851 TemplateParameterList *TemplateParams,
1852 const TemplateArgument *Params, unsigned NumParams,
1853 const TemplateArgument *Args, unsigned NumArgs,
1854 TemplateDeductionInfo &Info,
1855 SmallVectorImpl<DeducedTemplateArgument> &Deduced) {
1856 // C++0x [temp.deduct.type]p9:
1857 // If the template argument list of P contains a pack expansion that is not
1858 // the last template argument, the entire template argument list is a
1859 // non-deduced context.
1860 if (hasPackExpansionBeforeEnd(Params, NumParams))
1861 return Sema::TDK_Success;
1863 // C++0x [temp.deduct.type]p9:
1864 // If P has a form that contains <T> or <i>, then each argument Pi of the
1865 // respective template argument list P is compared with the corresponding
1866 // argument Ai of the corresponding template argument list of A.
1867 unsigned ArgIdx = 0, ParamIdx = 0;
1868 for (; hasTemplateArgumentForDeduction(Params, ParamIdx, NumParams);
1870 if (!Params[ParamIdx].isPackExpansion()) {
1871 // The simple case: deduce template arguments by matching Pi and Ai.
1873 // Check whether we have enough arguments.
1874 if (!hasTemplateArgumentForDeduction(Args, ArgIdx, NumArgs))
1875 return Sema::TDK_Success;
1877 if (Args[ArgIdx].isPackExpansion()) {
1878 // FIXME: We follow the logic of C++0x [temp.deduct.type]p22 here,
1879 // but applied to pack expansions that are template arguments.
1880 return Sema::TDK_MiscellaneousDeductionFailure;
1883 // Perform deduction for this Pi/Ai pair.
1884 if (Sema::TemplateDeductionResult Result
1885 = DeduceTemplateArguments(S, TemplateParams,
1886 Params[ParamIdx], Args[ArgIdx],
1890 // Move to the next argument.
1895 // The parameter is a pack expansion.
1897 // C++0x [temp.deduct.type]p9:
1898 // If Pi is a pack expansion, then the pattern of Pi is compared with
1899 // each remaining argument in the template argument list of A. Each
1900 // comparison deduces template arguments for subsequent positions in the
1901 // template parameter packs expanded by Pi.
1902 TemplateArgument Pattern = Params[ParamIdx].getPackExpansionPattern();
1904 // FIXME: If there are no remaining arguments, we can bail out early
1905 // and set any deduced parameter packs to an empty argument pack.
1906 // The latter part of this is a (minor) correctness issue.
1908 // Prepare to deduce the packs within the pattern.
1909 PackDeductionScope PackScope(S, TemplateParams, Deduced, Info, Pattern);
1911 // Keep track of the deduced template arguments for each parameter pack
1912 // expanded by this pack expansion (the outer index) and for each
1913 // template argument (the inner SmallVectors).
1914 bool HasAnyArguments = false;
1915 for (; hasTemplateArgumentForDeduction(Args, ArgIdx, NumArgs); ++ArgIdx) {
1916 HasAnyArguments = true;
1918 // Deduce template arguments from the pattern.
1919 if (Sema::TemplateDeductionResult Result
1920 = DeduceTemplateArguments(S, TemplateParams, Pattern, Args[ArgIdx],
1924 PackScope.nextPackElement();
1927 // Build argument packs for each of the parameter packs expanded by this
1929 if (auto Result = PackScope.finish(HasAnyArguments))
1933 return Sema::TDK_Success;
1936 static Sema::TemplateDeductionResult
1937 DeduceTemplateArguments(Sema &S,
1938 TemplateParameterList *TemplateParams,
1939 const TemplateArgumentList &ParamList,
1940 const TemplateArgumentList &ArgList,
1941 TemplateDeductionInfo &Info,
1942 SmallVectorImpl<DeducedTemplateArgument> &Deduced) {
1943 return DeduceTemplateArguments(S, TemplateParams,
1944 ParamList.data(), ParamList.size(),
1945 ArgList.data(), ArgList.size(),
1949 /// \brief Determine whether two template arguments are the same.
1950 static bool isSameTemplateArg(ASTContext &Context,
1951 const TemplateArgument &X,
1952 const TemplateArgument &Y) {
1953 if (X.getKind() != Y.getKind())
1956 switch (X.getKind()) {
1957 case TemplateArgument::Null:
1958 llvm_unreachable("Comparing NULL template argument");
1960 case TemplateArgument::Type:
1961 return Context.getCanonicalType(X.getAsType()) ==
1962 Context.getCanonicalType(Y.getAsType());
1964 case TemplateArgument::Declaration:
1965 return isSameDeclaration(X.getAsDecl(), Y.getAsDecl());
1967 case TemplateArgument::NullPtr:
1968 return Context.hasSameType(X.getNullPtrType(), Y.getNullPtrType());
1970 case TemplateArgument::Template:
1971 case TemplateArgument::TemplateExpansion:
1972 return Context.getCanonicalTemplateName(
1973 X.getAsTemplateOrTemplatePattern()).getAsVoidPointer() ==
1974 Context.getCanonicalTemplateName(
1975 Y.getAsTemplateOrTemplatePattern()).getAsVoidPointer();
1977 case TemplateArgument::Integral:
1978 return X.getAsIntegral() == Y.getAsIntegral();
1980 case TemplateArgument::Expression: {
1981 llvm::FoldingSetNodeID XID, YID;
1982 X.getAsExpr()->Profile(XID, Context, true);
1983 Y.getAsExpr()->Profile(YID, Context, true);
1987 case TemplateArgument::Pack:
1988 if (X.pack_size() != Y.pack_size())
1991 for (TemplateArgument::pack_iterator XP = X.pack_begin(),
1992 XPEnd = X.pack_end(),
1993 YP = Y.pack_begin();
1994 XP != XPEnd; ++XP, ++YP)
1995 if (!isSameTemplateArg(Context, *XP, *YP))
2001 llvm_unreachable("Invalid TemplateArgument Kind!");
2004 /// \brief Allocate a TemplateArgumentLoc where all locations have
2005 /// been initialized to the given location.
2007 /// \param S The semantic analysis object.
2009 /// \param Arg The template argument we are producing template argument
2010 /// location information for.
2012 /// \param NTTPType For a declaration template argument, the type of
2013 /// the non-type template parameter that corresponds to this template
2016 /// \param Loc The source location to use for the resulting template
2018 static TemplateArgumentLoc
2019 getTrivialTemplateArgumentLoc(Sema &S,
2020 const TemplateArgument &Arg,
2022 SourceLocation Loc) {
2023 switch (Arg.getKind()) {
2024 case TemplateArgument::Null:
2025 llvm_unreachable("Can't get a NULL template argument here");
2027 case TemplateArgument::Type:
2028 return TemplateArgumentLoc(Arg,
2029 S.Context.getTrivialTypeSourceInfo(Arg.getAsType(), Loc));
2031 case TemplateArgument::Declaration: {
2033 = S.BuildExpressionFromDeclTemplateArgument(Arg, NTTPType, Loc)
2035 return TemplateArgumentLoc(TemplateArgument(E), E);
2038 case TemplateArgument::NullPtr: {
2040 = S.BuildExpressionFromDeclTemplateArgument(Arg, NTTPType, Loc)
2042 return TemplateArgumentLoc(TemplateArgument(NTTPType, /*isNullPtr*/true),
2046 case TemplateArgument::Integral: {
2048 = S.BuildExpressionFromIntegralTemplateArgument(Arg, Loc).getAs<Expr>();
2049 return TemplateArgumentLoc(TemplateArgument(E), E);
2052 case TemplateArgument::Template:
2053 case TemplateArgument::TemplateExpansion: {
2054 NestedNameSpecifierLocBuilder Builder;
2055 TemplateName Template = Arg.getAsTemplate();
2056 if (DependentTemplateName *DTN = Template.getAsDependentTemplateName())
2057 Builder.MakeTrivial(S.Context, DTN->getQualifier(), Loc);
2058 else if (QualifiedTemplateName *QTN =
2059 Template.getAsQualifiedTemplateName())
2060 Builder.MakeTrivial(S.Context, QTN->getQualifier(), Loc);
2062 if (Arg.getKind() == TemplateArgument::Template)
2063 return TemplateArgumentLoc(Arg,
2064 Builder.getWithLocInContext(S.Context),
2068 return TemplateArgumentLoc(Arg, Builder.getWithLocInContext(S.Context),
2072 case TemplateArgument::Expression:
2073 return TemplateArgumentLoc(Arg, Arg.getAsExpr());
2075 case TemplateArgument::Pack:
2076 return TemplateArgumentLoc(Arg, TemplateArgumentLocInfo());
2079 llvm_unreachable("Invalid TemplateArgument Kind!");
2083 /// \brief Convert the given deduced template argument and add it to the set of
2084 /// fully-converted template arguments.
2086 ConvertDeducedTemplateArgument(Sema &S, NamedDecl *Param,
2087 DeducedTemplateArgument Arg,
2088 NamedDecl *Template,
2090 unsigned ArgumentPackIndex,
2091 TemplateDeductionInfo &Info,
2092 bool InFunctionTemplate,
2093 SmallVectorImpl<TemplateArgument> &Output) {
2094 if (Arg.getKind() == TemplateArgument::Pack) {
2095 // This is a template argument pack, so check each of its arguments against
2096 // the template parameter.
2097 SmallVector<TemplateArgument, 2> PackedArgsBuilder;
2098 for (const auto &P : Arg.pack_elements()) {
2099 // When converting the deduced template argument, append it to the
2100 // general output list. We need to do this so that the template argument
2101 // checking logic has all of the prior template arguments available.
2102 DeducedTemplateArgument InnerArg(P);
2103 InnerArg.setDeducedFromArrayBound(Arg.wasDeducedFromArrayBound());
2104 if (ConvertDeducedTemplateArgument(S, Param, InnerArg, Template,
2105 NTTPType, PackedArgsBuilder.size(),
2106 Info, InFunctionTemplate, Output))
2109 // Move the converted template argument into our argument pack.
2110 PackedArgsBuilder.push_back(Output.pop_back_val());
2113 // Create the resulting argument pack.
2114 Output.push_back(TemplateArgument::CreatePackCopy(S.Context,
2115 PackedArgsBuilder.data(),
2116 PackedArgsBuilder.size()));
2120 // Convert the deduced template argument into a template
2121 // argument that we can check, almost as if the user had written
2122 // the template argument explicitly.
2123 TemplateArgumentLoc ArgLoc = getTrivialTemplateArgumentLoc(S, Arg, NTTPType,
2124 Info.getLocation());
2126 // Check the template argument, converting it as necessary.
2127 return S.CheckTemplateArgument(Param, ArgLoc,
2129 Template->getLocation(),
2130 Template->getSourceRange().getEnd(),
2134 ? (Arg.wasDeducedFromArrayBound()
2135 ? Sema::CTAK_DeducedFromArrayBound
2136 : Sema::CTAK_Deduced)
2137 : Sema::CTAK_Specified);
2140 /// Complete template argument deduction for a class template partial
2142 static Sema::TemplateDeductionResult
2143 FinishTemplateArgumentDeduction(Sema &S,
2144 ClassTemplatePartialSpecializationDecl *Partial,
2145 const TemplateArgumentList &TemplateArgs,
2146 SmallVectorImpl<DeducedTemplateArgument> &Deduced,
2147 TemplateDeductionInfo &Info) {
2148 // Unevaluated SFINAE context.
2149 EnterExpressionEvaluationContext Unevaluated(S, Sema::Unevaluated);
2150 Sema::SFINAETrap Trap(S);
2152 Sema::ContextRAII SavedContext(S, Partial);
2154 // C++ [temp.deduct.type]p2:
2155 // [...] or if any template argument remains neither deduced nor
2156 // explicitly specified, template argument deduction fails.
2157 SmallVector<TemplateArgument, 4> Builder;
2158 TemplateParameterList *PartialParams = Partial->getTemplateParameters();
2159 for (unsigned I = 0, N = PartialParams->size(); I != N; ++I) {
2160 NamedDecl *Param = PartialParams->getParam(I);
2161 if (Deduced[I].isNull()) {
2162 Info.Param = makeTemplateParameter(Param);
2163 return Sema::TDK_Incomplete;
2166 // We have deduced this argument, so it still needs to be
2167 // checked and converted.
2169 // First, for a non-type template parameter type that is
2170 // initialized by a declaration, we need the type of the
2171 // corresponding non-type template parameter.
2173 if (NonTypeTemplateParmDecl *NTTP
2174 = dyn_cast<NonTypeTemplateParmDecl>(Param)) {
2175 NTTPType = NTTP->getType();
2176 if (NTTPType->isDependentType()) {
2177 TemplateArgumentList TemplateArgs(TemplateArgumentList::OnStack,
2178 Builder.data(), Builder.size());
2179 NTTPType = S.SubstType(NTTPType,
2180 MultiLevelTemplateArgumentList(TemplateArgs),
2181 NTTP->getLocation(),
2182 NTTP->getDeclName());
2183 if (NTTPType.isNull()) {
2184 Info.Param = makeTemplateParameter(Param);
2185 // FIXME: These template arguments are temporary. Free them!
2186 Info.reset(TemplateArgumentList::CreateCopy(S.Context,
2189 return Sema::TDK_SubstitutionFailure;
2194 if (ConvertDeducedTemplateArgument(S, Param, Deduced[I],
2195 Partial, NTTPType, 0, Info, false,
2197 Info.Param = makeTemplateParameter(Param);
2198 // FIXME: These template arguments are temporary. Free them!
2199 Info.reset(TemplateArgumentList::CreateCopy(S.Context, Builder.data(),
2201 return Sema::TDK_SubstitutionFailure;
2205 // Form the template argument list from the deduced template arguments.
2206 TemplateArgumentList *DeducedArgumentList
2207 = TemplateArgumentList::CreateCopy(S.Context, Builder.data(),
2210 Info.reset(DeducedArgumentList);
2212 // Substitute the deduced template arguments into the template
2213 // arguments of the class template partial specialization, and
2214 // verify that the instantiated template arguments are both valid
2215 // and are equivalent to the template arguments originally provided
2216 // to the class template.
2217 LocalInstantiationScope InstScope(S);
2218 ClassTemplateDecl *ClassTemplate = Partial->getSpecializedTemplate();
2219 const ASTTemplateArgumentListInfo *PartialTemplArgInfo
2220 = Partial->getTemplateArgsAsWritten();
2221 const TemplateArgumentLoc *PartialTemplateArgs
2222 = PartialTemplArgInfo->getTemplateArgs();
2224 TemplateArgumentListInfo InstArgs(PartialTemplArgInfo->LAngleLoc,
2225 PartialTemplArgInfo->RAngleLoc);
2227 if (S.Subst(PartialTemplateArgs, PartialTemplArgInfo->NumTemplateArgs,
2228 InstArgs, MultiLevelTemplateArgumentList(*DeducedArgumentList))) {
2229 unsigned ArgIdx = InstArgs.size(), ParamIdx = ArgIdx;
2230 if (ParamIdx >= Partial->getTemplateParameters()->size())
2231 ParamIdx = Partial->getTemplateParameters()->size() - 1;
2234 = const_cast<NamedDecl *>(
2235 Partial->getTemplateParameters()->getParam(ParamIdx));
2236 Info.Param = makeTemplateParameter(Param);
2237 Info.FirstArg = PartialTemplateArgs[ArgIdx].getArgument();
2238 return Sema::TDK_SubstitutionFailure;
2241 SmallVector<TemplateArgument, 4> ConvertedInstArgs;
2242 if (S.CheckTemplateArgumentList(ClassTemplate, Partial->getLocation(),
2243 InstArgs, false, ConvertedInstArgs))
2244 return Sema::TDK_SubstitutionFailure;
2246 TemplateParameterList *TemplateParams
2247 = ClassTemplate->getTemplateParameters();
2248 for (unsigned I = 0, E = TemplateParams->size(); I != E; ++I) {
2249 TemplateArgument InstArg = ConvertedInstArgs.data()[I];
2250 if (!isSameTemplateArg(S.Context, TemplateArgs[I], InstArg)) {
2251 Info.Param = makeTemplateParameter(TemplateParams->getParam(I));
2252 Info.FirstArg = TemplateArgs[I];
2253 Info.SecondArg = InstArg;
2254 return Sema::TDK_NonDeducedMismatch;
2258 if (Trap.hasErrorOccurred())
2259 return Sema::TDK_SubstitutionFailure;
2261 return Sema::TDK_Success;
2264 /// \brief Perform template argument deduction to determine whether
2265 /// the given template arguments match the given class template
2266 /// partial specialization per C++ [temp.class.spec.match].
2267 Sema::TemplateDeductionResult
2268 Sema::DeduceTemplateArguments(ClassTemplatePartialSpecializationDecl *Partial,
2269 const TemplateArgumentList &TemplateArgs,
2270 TemplateDeductionInfo &Info) {
2271 if (Partial->isInvalidDecl())
2274 // C++ [temp.class.spec.match]p2:
2275 // A partial specialization matches a given actual template
2276 // argument list if the template arguments of the partial
2277 // specialization can be deduced from the actual template argument
2280 // Unevaluated SFINAE context.
2281 EnterExpressionEvaluationContext Unevaluated(*this, Sema::Unevaluated);
2282 SFINAETrap Trap(*this);
2284 SmallVector<DeducedTemplateArgument, 4> Deduced;
2285 Deduced.resize(Partial->getTemplateParameters()->size());
2286 if (TemplateDeductionResult Result
2287 = ::DeduceTemplateArguments(*this,
2288 Partial->getTemplateParameters(),
2289 Partial->getTemplateArgs(),
2290 TemplateArgs, Info, Deduced))
2293 SmallVector<TemplateArgument, 4> DeducedArgs(Deduced.begin(), Deduced.end());
2294 InstantiatingTemplate Inst(*this, Info.getLocation(), Partial, DeducedArgs,
2296 if (Inst.isInvalid())
2297 return TDK_InstantiationDepth;
2299 if (Trap.hasErrorOccurred())
2300 return Sema::TDK_SubstitutionFailure;
2302 return ::FinishTemplateArgumentDeduction(*this, Partial, TemplateArgs,
2306 /// Complete template argument deduction for a variable template partial
2308 /// TODO: Unify with ClassTemplatePartialSpecializationDecl version?
2309 /// May require unifying ClassTemplate(Partial)SpecializationDecl and
2310 /// VarTemplate(Partial)SpecializationDecl with a new data
2311 /// structure Template(Partial)SpecializationDecl, and
2312 /// using Template(Partial)SpecializationDecl as input type.
2313 static Sema::TemplateDeductionResult FinishTemplateArgumentDeduction(
2314 Sema &S, VarTemplatePartialSpecializationDecl *Partial,
2315 const TemplateArgumentList &TemplateArgs,
2316 SmallVectorImpl<DeducedTemplateArgument> &Deduced,
2317 TemplateDeductionInfo &Info) {
2318 // Unevaluated SFINAE context.
2319 EnterExpressionEvaluationContext Unevaluated(S, Sema::Unevaluated);
2320 Sema::SFINAETrap Trap(S);
2322 // C++ [temp.deduct.type]p2:
2323 // [...] or if any template argument remains neither deduced nor
2324 // explicitly specified, template argument deduction fails.
2325 SmallVector<TemplateArgument, 4> Builder;
2326 TemplateParameterList *PartialParams = Partial->getTemplateParameters();
2327 for (unsigned I = 0, N = PartialParams->size(); I != N; ++I) {
2328 NamedDecl *Param = PartialParams->getParam(I);
2329 if (Deduced[I].isNull()) {
2330 Info.Param = makeTemplateParameter(Param);
2331 return Sema::TDK_Incomplete;
2334 // We have deduced this argument, so it still needs to be
2335 // checked and converted.
2337 // First, for a non-type template parameter type that is
2338 // initialized by a declaration, we need the type of the
2339 // corresponding non-type template parameter.
2341 if (NonTypeTemplateParmDecl *NTTP =
2342 dyn_cast<NonTypeTemplateParmDecl>(Param)) {
2343 NTTPType = NTTP->getType();
2344 if (NTTPType->isDependentType()) {
2345 TemplateArgumentList TemplateArgs(TemplateArgumentList::OnStack,
2346 Builder.data(), Builder.size());
2348 S.SubstType(NTTPType, MultiLevelTemplateArgumentList(TemplateArgs),
2349 NTTP->getLocation(), NTTP->getDeclName());
2350 if (NTTPType.isNull()) {
2351 Info.Param = makeTemplateParameter(Param);
2352 // FIXME: These template arguments are temporary. Free them!
2353 Info.reset(TemplateArgumentList::CreateCopy(S.Context, Builder.data(),
2355 return Sema::TDK_SubstitutionFailure;
2360 if (ConvertDeducedTemplateArgument(S, Param, Deduced[I], Partial, NTTPType,
2361 0, Info, false, Builder)) {
2362 Info.Param = makeTemplateParameter(Param);
2363 // FIXME: These template arguments are temporary. Free them!
2364 Info.reset(TemplateArgumentList::CreateCopy(S.Context, Builder.data(),
2366 return Sema::TDK_SubstitutionFailure;
2370 // Form the template argument list from the deduced template arguments.
2371 TemplateArgumentList *DeducedArgumentList = TemplateArgumentList::CreateCopy(
2372 S.Context, Builder.data(), Builder.size());
2374 Info.reset(DeducedArgumentList);
2376 // Substitute the deduced template arguments into the template
2377 // arguments of the class template partial specialization, and
2378 // verify that the instantiated template arguments are both valid
2379 // and are equivalent to the template arguments originally provided
2380 // to the class template.
2381 LocalInstantiationScope InstScope(S);
2382 VarTemplateDecl *VarTemplate = Partial->getSpecializedTemplate();
2383 const ASTTemplateArgumentListInfo *PartialTemplArgInfo
2384 = Partial->getTemplateArgsAsWritten();
2385 const TemplateArgumentLoc *PartialTemplateArgs
2386 = PartialTemplArgInfo->getTemplateArgs();
2388 TemplateArgumentListInfo InstArgs(PartialTemplArgInfo->LAngleLoc,
2389 PartialTemplArgInfo->RAngleLoc);
2391 if (S.Subst(PartialTemplateArgs, PartialTemplArgInfo->NumTemplateArgs,
2392 InstArgs, MultiLevelTemplateArgumentList(*DeducedArgumentList))) {
2393 unsigned ArgIdx = InstArgs.size(), ParamIdx = ArgIdx;
2394 if (ParamIdx >= Partial->getTemplateParameters()->size())
2395 ParamIdx = Partial->getTemplateParameters()->size() - 1;
2397 Decl *Param = const_cast<NamedDecl *>(
2398 Partial->getTemplateParameters()->getParam(ParamIdx));
2399 Info.Param = makeTemplateParameter(Param);
2400 Info.FirstArg = PartialTemplateArgs[ArgIdx].getArgument();
2401 return Sema::TDK_SubstitutionFailure;
2403 SmallVector<TemplateArgument, 4> ConvertedInstArgs;
2404 if (S.CheckTemplateArgumentList(VarTemplate, Partial->getLocation(), InstArgs,
2405 false, ConvertedInstArgs))
2406 return Sema::TDK_SubstitutionFailure;
2408 TemplateParameterList *TemplateParams = VarTemplate->getTemplateParameters();
2409 for (unsigned I = 0, E = TemplateParams->size(); I != E; ++I) {
2410 TemplateArgument InstArg = ConvertedInstArgs.data()[I];
2411 if (!isSameTemplateArg(S.Context, TemplateArgs[I], InstArg)) {
2412 Info.Param = makeTemplateParameter(TemplateParams->getParam(I));
2413 Info.FirstArg = TemplateArgs[I];
2414 Info.SecondArg = InstArg;
2415 return Sema::TDK_NonDeducedMismatch;
2419 if (Trap.hasErrorOccurred())
2420 return Sema::TDK_SubstitutionFailure;
2422 return Sema::TDK_Success;
2425 /// \brief Perform template argument deduction to determine whether
2426 /// the given template arguments match the given variable template
2427 /// partial specialization per C++ [temp.class.spec.match].
2428 /// TODO: Unify with ClassTemplatePartialSpecializationDecl version?
2429 /// May require unifying ClassTemplate(Partial)SpecializationDecl and
2430 /// VarTemplate(Partial)SpecializationDecl with a new data
2431 /// structure Template(Partial)SpecializationDecl, and
2432 /// using Template(Partial)SpecializationDecl as input type.
2433 Sema::TemplateDeductionResult
2434 Sema::DeduceTemplateArguments(VarTemplatePartialSpecializationDecl *Partial,
2435 const TemplateArgumentList &TemplateArgs,
2436 TemplateDeductionInfo &Info) {
2437 if (Partial->isInvalidDecl())
2440 // C++ [temp.class.spec.match]p2:
2441 // A partial specialization matches a given actual template
2442 // argument list if the template arguments of the partial
2443 // specialization can be deduced from the actual template argument
2446 // Unevaluated SFINAE context.
2447 EnterExpressionEvaluationContext Unevaluated(*this, Sema::Unevaluated);
2448 SFINAETrap Trap(*this);
2450 SmallVector<DeducedTemplateArgument, 4> Deduced;
2451 Deduced.resize(Partial->getTemplateParameters()->size());
2452 if (TemplateDeductionResult Result = ::DeduceTemplateArguments(
2453 *this, Partial->getTemplateParameters(), Partial->getTemplateArgs(),
2454 TemplateArgs, Info, Deduced))
2457 SmallVector<TemplateArgument, 4> DeducedArgs(Deduced.begin(), Deduced.end());
2458 InstantiatingTemplate Inst(*this, Info.getLocation(), Partial, DeducedArgs,
2460 if (Inst.isInvalid())
2461 return TDK_InstantiationDepth;
2463 if (Trap.hasErrorOccurred())
2464 return Sema::TDK_SubstitutionFailure;
2466 return ::FinishTemplateArgumentDeduction(*this, Partial, TemplateArgs,
2470 /// \brief Determine whether the given type T is a simple-template-id type.
2471 static bool isSimpleTemplateIdType(QualType T) {
2472 if (const TemplateSpecializationType *Spec
2473 = T->getAs<TemplateSpecializationType>())
2474 return Spec->getTemplateName().getAsTemplateDecl() != nullptr;
2479 /// \brief Substitute the explicitly-provided template arguments into the
2480 /// given function template according to C++ [temp.arg.explicit].
2482 /// \param FunctionTemplate the function template into which the explicit
2483 /// template arguments will be substituted.
2485 /// \param ExplicitTemplateArgs the explicitly-specified template
2488 /// \param Deduced the deduced template arguments, which will be populated
2489 /// with the converted and checked explicit template arguments.
2491 /// \param ParamTypes will be populated with the instantiated function
2494 /// \param FunctionType if non-NULL, the result type of the function template
2495 /// will also be instantiated and the pointed-to value will be updated with
2496 /// the instantiated function type.
2498 /// \param Info if substitution fails for any reason, this object will be
2499 /// populated with more information about the failure.
2501 /// \returns TDK_Success if substitution was successful, or some failure
2503 Sema::TemplateDeductionResult
2504 Sema::SubstituteExplicitTemplateArguments(
2505 FunctionTemplateDecl *FunctionTemplate,
2506 TemplateArgumentListInfo &ExplicitTemplateArgs,
2507 SmallVectorImpl<DeducedTemplateArgument> &Deduced,
2508 SmallVectorImpl<QualType> &ParamTypes,
2509 QualType *FunctionType,
2510 TemplateDeductionInfo &Info) {
2511 FunctionDecl *Function = FunctionTemplate->getTemplatedDecl();
2512 TemplateParameterList *TemplateParams
2513 = FunctionTemplate->getTemplateParameters();
2515 if (ExplicitTemplateArgs.size() == 0) {
2516 // No arguments to substitute; just copy over the parameter types and
2517 // fill in the function type.
2518 for (auto P : Function->params())
2519 ParamTypes.push_back(P->getType());
2522 *FunctionType = Function->getType();
2526 // Unevaluated SFINAE context.
2527 EnterExpressionEvaluationContext Unevaluated(*this, Sema::Unevaluated);
2528 SFINAETrap Trap(*this);
2530 // C++ [temp.arg.explicit]p3:
2531 // Template arguments that are present shall be specified in the
2532 // declaration order of their corresponding template-parameters. The
2533 // template argument list shall not specify more template-arguments than
2534 // there are corresponding template-parameters.
2535 SmallVector<TemplateArgument, 4> Builder;
2537 // Enter a new template instantiation context where we check the
2538 // explicitly-specified template arguments against this function template,
2539 // and then substitute them into the function parameter types.
2540 SmallVector<TemplateArgument, 4> DeducedArgs(Deduced.begin(), Deduced.end());
2541 InstantiatingTemplate Inst(*this, Info.getLocation(), FunctionTemplate,
2543 ActiveTemplateInstantiation::ExplicitTemplateArgumentSubstitution,
2545 if (Inst.isInvalid())
2546 return TDK_InstantiationDepth;
2548 if (CheckTemplateArgumentList(FunctionTemplate,
2550 ExplicitTemplateArgs,
2552 Builder) || Trap.hasErrorOccurred()) {
2553 unsigned Index = Builder.size();
2554 if (Index >= TemplateParams->size())
2555 Index = TemplateParams->size() - 1;
2556 Info.Param = makeTemplateParameter(TemplateParams->getParam(Index));
2557 return TDK_InvalidExplicitArguments;
2560 // Form the template argument list from the explicitly-specified
2561 // template arguments.
2562 TemplateArgumentList *ExplicitArgumentList
2563 = TemplateArgumentList::CreateCopy(Context, Builder.data(), Builder.size());
2564 Info.reset(ExplicitArgumentList);
2566 // Template argument deduction and the final substitution should be
2567 // done in the context of the templated declaration. Explicit
2568 // argument substitution, on the other hand, needs to happen in the
2570 ContextRAII SavedContext(*this, FunctionTemplate->getTemplatedDecl());
2572 // If we deduced template arguments for a template parameter pack,
2573 // note that the template argument pack is partially substituted and record
2574 // the explicit template arguments. They'll be used as part of deduction
2575 // for this template parameter pack.
2576 for (unsigned I = 0, N = Builder.size(); I != N; ++I) {
2577 const TemplateArgument &Arg = Builder[I];
2578 if (Arg.getKind() == TemplateArgument::Pack) {
2579 CurrentInstantiationScope->SetPartiallySubstitutedPack(
2580 TemplateParams->getParam(I),
2587 const FunctionProtoType *Proto
2588 = Function->getType()->getAs<FunctionProtoType>();
2589 assert(Proto && "Function template does not have a prototype?");
2591 // Isolate our substituted parameters from our caller.
2592 LocalInstantiationScope InstScope(*this, /*MergeWithOuterScope*/true);
2594 // Instantiate the types of each of the function parameters given the
2595 // explicitly-specified template arguments. If the function has a trailing
2596 // return type, substitute it after the arguments to ensure we substitute
2597 // in lexical order.
2598 if (Proto->hasTrailingReturn()) {
2599 if (SubstParmTypes(Function->getLocation(),
2600 Function->param_begin(), Function->getNumParams(),
2601 MultiLevelTemplateArgumentList(*ExplicitArgumentList),
2603 return TDK_SubstitutionFailure;
2606 // Instantiate the return type.
2607 QualType ResultType;
2609 // C++11 [expr.prim.general]p3:
2610 // If a declaration declares a member function or member function
2611 // template of a class X, the expression this is a prvalue of type
2612 // "pointer to cv-qualifier-seq X" between the optional cv-qualifer-seq
2613 // and the end of the function-definition, member-declarator, or
2615 unsigned ThisTypeQuals = 0;
2616 CXXRecordDecl *ThisContext = nullptr;
2617 if (CXXMethodDecl *Method = dyn_cast<CXXMethodDecl>(Function)) {
2618 ThisContext = Method->getParent();
2619 ThisTypeQuals = Method->getTypeQualifiers();
2622 CXXThisScopeRAII ThisScope(*this, ThisContext, ThisTypeQuals,
2623 getLangOpts().CPlusPlus11);
2626 SubstType(Proto->getReturnType(),
2627 MultiLevelTemplateArgumentList(*ExplicitArgumentList),
2628 Function->getTypeSpecStartLoc(), Function->getDeclName());
2629 if (ResultType.isNull() || Trap.hasErrorOccurred())
2630 return TDK_SubstitutionFailure;
2633 // Instantiate the types of each of the function parameters given the
2634 // explicitly-specified template arguments if we didn't do so earlier.
2635 if (!Proto->hasTrailingReturn() &&
2636 SubstParmTypes(Function->getLocation(),
2637 Function->param_begin(), Function->getNumParams(),
2638 MultiLevelTemplateArgumentList(*ExplicitArgumentList),
2640 return TDK_SubstitutionFailure;
2643 *FunctionType = BuildFunctionType(ResultType, ParamTypes,
2644 Function->getLocation(),
2645 Function->getDeclName(),
2646 Proto->getExtProtoInfo());
2647 if (FunctionType->isNull() || Trap.hasErrorOccurred())
2648 return TDK_SubstitutionFailure;
2651 // C++ [temp.arg.explicit]p2:
2652 // Trailing template arguments that can be deduced (14.8.2) may be
2653 // omitted from the list of explicit template-arguments. If all of the
2654 // template arguments can be deduced, they may all be omitted; in this
2655 // case, the empty template argument list <> itself may also be omitted.
2657 // Take all of the explicitly-specified arguments and put them into
2658 // the set of deduced template arguments. Explicitly-specified
2659 // parameter packs, however, will be set to NULL since the deduction
2660 // mechanisms handle explicitly-specified argument packs directly.
2661 Deduced.reserve(TemplateParams->size());
2662 for (unsigned I = 0, N = ExplicitArgumentList->size(); I != N; ++I) {
2663 const TemplateArgument &Arg = ExplicitArgumentList->get(I);
2664 if (Arg.getKind() == TemplateArgument::Pack)
2665 Deduced.push_back(DeducedTemplateArgument());
2667 Deduced.push_back(Arg);
2673 /// \brief Check whether the deduced argument type for a call to a function
2674 /// template matches the actual argument type per C++ [temp.deduct.call]p4.
2676 CheckOriginalCallArgDeduction(Sema &S, Sema::OriginalCallArg OriginalArg,
2677 QualType DeducedA) {
2678 ASTContext &Context = S.Context;
2680 QualType A = OriginalArg.OriginalArgType;
2681 QualType OriginalParamType = OriginalArg.OriginalParamType;
2683 // Check for type equality (top-level cv-qualifiers are ignored).
2684 if (Context.hasSameUnqualifiedType(A, DeducedA))
2687 // Strip off references on the argument types; they aren't needed for
2688 // the following checks.
2689 if (const ReferenceType *DeducedARef = DeducedA->getAs<ReferenceType>())
2690 DeducedA = DeducedARef->getPointeeType();
2691 if (const ReferenceType *ARef = A->getAs<ReferenceType>())
2692 A = ARef->getPointeeType();
2694 // C++ [temp.deduct.call]p4:
2695 // [...] However, there are three cases that allow a difference:
2696 // - If the original P is a reference type, the deduced A (i.e., the
2697 // type referred to by the reference) can be more cv-qualified than
2698 // the transformed A.
2699 if (const ReferenceType *OriginalParamRef
2700 = OriginalParamType->getAs<ReferenceType>()) {
2701 // We don't want to keep the reference around any more.
2702 OriginalParamType = OriginalParamRef->getPointeeType();
2704 Qualifiers AQuals = A.getQualifiers();
2705 Qualifiers DeducedAQuals = DeducedA.getQualifiers();
2707 // Under Objective-C++ ARC, the deduced type may have implicitly
2708 // been given strong or (when dealing with a const reference)
2709 // unsafe_unretained lifetime. If so, update the original
2710 // qualifiers to include this lifetime.
2711 if (S.getLangOpts().ObjCAutoRefCount &&
2712 ((DeducedAQuals.getObjCLifetime() == Qualifiers::OCL_Strong &&
2713 AQuals.getObjCLifetime() == Qualifiers::OCL_None) ||
2714 (DeducedAQuals.hasConst() &&
2715 DeducedAQuals.getObjCLifetime() == Qualifiers::OCL_ExplicitNone))) {
2716 AQuals.setObjCLifetime(DeducedAQuals.getObjCLifetime());
2719 if (AQuals == DeducedAQuals) {
2720 // Qualifiers match; there's nothing to do.
2721 } else if (!DeducedAQuals.compatiblyIncludes(AQuals)) {
2724 // Qualifiers are compatible, so have the argument type adopt the
2725 // deduced argument type's qualifiers as if we had performed the
2726 // qualification conversion.
2727 A = Context.getQualifiedType(A.getUnqualifiedType(), DeducedAQuals);
2731 // - The transformed A can be another pointer or pointer to member
2732 // type that can be converted to the deduced A via a qualification
2735 // Also allow conversions which merely strip [[noreturn]] from function types
2736 // (recursively) as an extension.
2737 // FIXME: Currently, this doesn't play nicely with qualification conversions.
2738 bool ObjCLifetimeConversion = false;
2740 if ((A->isAnyPointerType() || A->isMemberPointerType()) &&
2741 (S.IsQualificationConversion(A, DeducedA, false,
2742 ObjCLifetimeConversion) ||
2743 S.IsNoReturnConversion(A, DeducedA, ResultTy)))
2747 // - If P is a class and P has the form simple-template-id, then the
2748 // transformed A can be a derived class of the deduced A. [...]
2749 // [...] Likewise, if P is a pointer to a class of the form
2750 // simple-template-id, the transformed A can be a pointer to a
2751 // derived class pointed to by the deduced A.
2752 if (const PointerType *OriginalParamPtr
2753 = OriginalParamType->getAs<PointerType>()) {
2754 if (const PointerType *DeducedAPtr = DeducedA->getAs<PointerType>()) {
2755 if (const PointerType *APtr = A->getAs<PointerType>()) {
2756 if (A->getPointeeType()->isRecordType()) {
2757 OriginalParamType = OriginalParamPtr->getPointeeType();
2758 DeducedA = DeducedAPtr->getPointeeType();
2759 A = APtr->getPointeeType();
2765 if (Context.hasSameUnqualifiedType(A, DeducedA))
2768 if (A->isRecordType() && isSimpleTemplateIdType(OriginalParamType) &&
2769 S.IsDerivedFrom(A, DeducedA))
2775 /// \brief Finish template argument deduction for a function template,
2776 /// checking the deduced template arguments for completeness and forming
2777 /// the function template specialization.
2779 /// \param OriginalCallArgs If non-NULL, the original call arguments against
2780 /// which the deduced argument types should be compared.
2781 Sema::TemplateDeductionResult
2782 Sema::FinishTemplateArgumentDeduction(FunctionTemplateDecl *FunctionTemplate,
2783 SmallVectorImpl<DeducedTemplateArgument> &Deduced,
2784 unsigned NumExplicitlySpecified,
2785 FunctionDecl *&Specialization,
2786 TemplateDeductionInfo &Info,
2787 SmallVectorImpl<OriginalCallArg> const *OriginalCallArgs) {
2788 TemplateParameterList *TemplateParams
2789 = FunctionTemplate->getTemplateParameters();
2791 // Unevaluated SFINAE context.
2792 EnterExpressionEvaluationContext Unevaluated(*this, Sema::Unevaluated);
2793 SFINAETrap Trap(*this);
2795 // Enter a new template instantiation context while we instantiate the
2796 // actual function declaration.
2797 SmallVector<TemplateArgument, 4> DeducedArgs(Deduced.begin(), Deduced.end());
2798 InstantiatingTemplate Inst(*this, Info.getLocation(), FunctionTemplate,
2800 ActiveTemplateInstantiation::DeducedTemplateArgumentSubstitution,
2802 if (Inst.isInvalid())
2803 return TDK_InstantiationDepth;
2805 ContextRAII SavedContext(*this, FunctionTemplate->getTemplatedDecl());
2807 // C++ [temp.deduct.type]p2:
2808 // [...] or if any template argument remains neither deduced nor
2809 // explicitly specified, template argument deduction fails.
2810 SmallVector<TemplateArgument, 4> Builder;
2811 for (unsigned I = 0, N = TemplateParams->size(); I != N; ++I) {
2812 NamedDecl *Param = TemplateParams->getParam(I);
2814 if (!Deduced[I].isNull()) {
2815 if (I < NumExplicitlySpecified) {
2816 // We have already fully type-checked and converted this
2817 // argument, because it was explicitly-specified. Just record the
2818 // presence of this argument.
2819 Builder.push_back(Deduced[I]);
2820 // We may have had explicitly-specified template arguments for a
2821 // template parameter pack (that may or may not have been extended
2822 // via additional deduced arguments).
2823 if (Param->isParameterPack() && CurrentInstantiationScope) {
2824 if (CurrentInstantiationScope->getPartiallySubstitutedPack() ==
2826 // Forget the partially-substituted pack; its substitution is now
2828 CurrentInstantiationScope->ResetPartiallySubstitutedPack();
2833 // We have deduced this argument, so it still needs to be
2834 // checked and converted.
2836 // First, for a non-type template parameter type that is
2837 // initialized by a declaration, we need the type of the
2838 // corresponding non-type template parameter.
2840 if (NonTypeTemplateParmDecl *NTTP
2841 = dyn_cast<NonTypeTemplateParmDecl>(Param)) {
2842 NTTPType = NTTP->getType();
2843 if (NTTPType->isDependentType()) {
2844 TemplateArgumentList TemplateArgs(TemplateArgumentList::OnStack,
2845 Builder.data(), Builder.size());
2846 NTTPType = SubstType(NTTPType,
2847 MultiLevelTemplateArgumentList(TemplateArgs),
2848 NTTP->getLocation(),
2849 NTTP->getDeclName());
2850 if (NTTPType.isNull()) {
2851 Info.Param = makeTemplateParameter(Param);
2852 // FIXME: These template arguments are temporary. Free them!
2853 Info.reset(TemplateArgumentList::CreateCopy(Context,
2856 return TDK_SubstitutionFailure;
2861 if (ConvertDeducedTemplateArgument(*this, Param, Deduced[I],
2862 FunctionTemplate, NTTPType, 0, Info,
2864 Info.Param = makeTemplateParameter(Param);
2865 // FIXME: These template arguments are temporary. Free them!
2866 Info.reset(TemplateArgumentList::CreateCopy(Context, Builder.data(),
2868 return TDK_SubstitutionFailure;
2874 // C++0x [temp.arg.explicit]p3:
2875 // A trailing template parameter pack (14.5.3) not otherwise deduced will
2876 // be deduced to an empty sequence of template arguments.
2877 // FIXME: Where did the word "trailing" come from?
2878 if (Param->isTemplateParameterPack()) {
2879 // We may have had explicitly-specified template arguments for this
2880 // template parameter pack. If so, our empty deduction extends the
2881 // explicitly-specified set (C++0x [temp.arg.explicit]p9).
2882 const TemplateArgument *ExplicitArgs;
2883 unsigned NumExplicitArgs;
2884 if (CurrentInstantiationScope &&
2885 CurrentInstantiationScope->getPartiallySubstitutedPack(&ExplicitArgs,
2888 Builder.push_back(TemplateArgument(ExplicitArgs, NumExplicitArgs));
2890 // Forget the partially-substituted pack; it's substitution is now
2892 CurrentInstantiationScope->ResetPartiallySubstitutedPack();
2894 Builder.push_back(TemplateArgument::getEmptyPack());
2899 // Substitute into the default template argument, if available.
2900 bool HasDefaultArg = false;
2901 TemplateArgumentLoc DefArg
2902 = SubstDefaultTemplateArgumentIfAvailable(FunctionTemplate,
2903 FunctionTemplate->getLocation(),
2904 FunctionTemplate->getSourceRange().getEnd(),
2906 Builder, HasDefaultArg);
2908 // If there was no default argument, deduction is incomplete.
2909 if (DefArg.getArgument().isNull()) {
2910 Info.Param = makeTemplateParameter(
2911 const_cast<NamedDecl *>(TemplateParams->getParam(I)));
2912 Info.reset(TemplateArgumentList::CreateCopy(Context, Builder.data(),
2914 return HasDefaultArg ? TDK_SubstitutionFailure : TDK_Incomplete;
2917 // Check whether we can actually use the default argument.
2918 if (CheckTemplateArgument(Param, DefArg,
2920 FunctionTemplate->getLocation(),
2921 FunctionTemplate->getSourceRange().getEnd(),
2924 Info.Param = makeTemplateParameter(
2925 const_cast<NamedDecl *>(TemplateParams->getParam(I)));
2926 // FIXME: These template arguments are temporary. Free them!
2927 Info.reset(TemplateArgumentList::CreateCopy(Context, Builder.data(),
2929 return TDK_SubstitutionFailure;
2932 // If we get here, we successfully used the default template argument.
2935 // Form the template argument list from the deduced template arguments.
2936 TemplateArgumentList *DeducedArgumentList
2937 = TemplateArgumentList::CreateCopy(Context, Builder.data(), Builder.size());
2938 Info.reset(DeducedArgumentList);
2940 // Substitute the deduced template arguments into the function template
2941 // declaration to produce the function template specialization.
2942 DeclContext *Owner = FunctionTemplate->getDeclContext();
2943 if (FunctionTemplate->getFriendObjectKind())
2944 Owner = FunctionTemplate->getLexicalDeclContext();
2945 Specialization = cast_or_null<FunctionDecl>(
2946 SubstDecl(FunctionTemplate->getTemplatedDecl(), Owner,
2947 MultiLevelTemplateArgumentList(*DeducedArgumentList)));
2948 if (!Specialization || Specialization->isInvalidDecl())
2949 return TDK_SubstitutionFailure;
2951 assert(Specialization->getPrimaryTemplate()->getCanonicalDecl() ==
2952 FunctionTemplate->getCanonicalDecl());
2954 // If the template argument list is owned by the function template
2955 // specialization, release it.
2956 if (Specialization->getTemplateSpecializationArgs() == DeducedArgumentList &&
2957 !Trap.hasErrorOccurred())
2960 // There may have been an error that did not prevent us from constructing a
2961 // declaration. Mark the declaration invalid and return with a substitution
2963 if (Trap.hasErrorOccurred()) {
2964 Specialization->setInvalidDecl(true);
2965 return TDK_SubstitutionFailure;
2968 if (OriginalCallArgs) {
2969 // C++ [temp.deduct.call]p4:
2970 // In general, the deduction process attempts to find template argument
2971 // values that will make the deduced A identical to A (after the type A
2972 // is transformed as described above). [...]
2973 for (unsigned I = 0, N = OriginalCallArgs->size(); I != N; ++I) {
2974 OriginalCallArg OriginalArg = (*OriginalCallArgs)[I];
2975 unsigned ParamIdx = OriginalArg.ArgIdx;
2977 if (ParamIdx >= Specialization->getNumParams())
2980 QualType DeducedA = Specialization->getParamDecl(ParamIdx)->getType();
2981 if (CheckOriginalCallArgDeduction(*this, OriginalArg, DeducedA))
2982 return Sema::TDK_SubstitutionFailure;
2986 // If we suppressed any diagnostics while performing template argument
2987 // deduction, and if we haven't already instantiated this declaration,
2988 // keep track of these diagnostics. They'll be emitted if this specialization
2989 // is actually used.
2990 if (Info.diag_begin() != Info.diag_end()) {
2991 SuppressedDiagnosticsMap::iterator
2992 Pos = SuppressedDiagnostics.find(Specialization->getCanonicalDecl());
2993 if (Pos == SuppressedDiagnostics.end())
2994 SuppressedDiagnostics[Specialization->getCanonicalDecl()]
2995 .append(Info.diag_begin(), Info.diag_end());
3001 /// Gets the type of a function for template-argument-deducton
3002 /// purposes when it's considered as part of an overload set.
3003 static QualType GetTypeOfFunction(Sema &S, const OverloadExpr::FindResult &R,
3005 // We may need to deduce the return type of the function now.
3006 if (S.getLangOpts().CPlusPlus14 && Fn->getReturnType()->isUndeducedType() &&
3007 S.DeduceReturnType(Fn, R.Expression->getExprLoc(), /*Diagnose*/ false))
3010 if (CXXMethodDecl *Method = dyn_cast<CXXMethodDecl>(Fn))
3011 if (Method->isInstance()) {
3012 // An instance method that's referenced in a form that doesn't
3013 // look like a member pointer is just invalid.
3014 if (!R.HasFormOfMemberPointer) return QualType();
3016 return S.Context.getMemberPointerType(Fn->getType(),
3017 S.Context.getTypeDeclType(Method->getParent()).getTypePtr());
3020 if (!R.IsAddressOfOperand) return Fn->getType();
3021 return S.Context.getPointerType(Fn->getType());
3024 /// Apply the deduction rules for overload sets.
3026 /// \return the null type if this argument should be treated as an
3027 /// undeduced context
3029 ResolveOverloadForDeduction(Sema &S, TemplateParameterList *TemplateParams,
3030 Expr *Arg, QualType ParamType,
3031 bool ParamWasReference) {
3033 OverloadExpr::FindResult R = OverloadExpr::find(Arg);
3035 OverloadExpr *Ovl = R.Expression;
3037 // C++0x [temp.deduct.call]p4
3039 if (ParamWasReference)
3040 TDF |= TDF_ParamWithReferenceType;
3041 if (R.IsAddressOfOperand)
3042 TDF |= TDF_IgnoreQualifiers;
3044 // C++0x [temp.deduct.call]p6:
3045 // When P is a function type, pointer to function type, or pointer
3046 // to member function type:
3048 if (!ParamType->isFunctionType() &&
3049 !ParamType->isFunctionPointerType() &&
3050 !ParamType->isMemberFunctionPointerType()) {
3051 if (Ovl->hasExplicitTemplateArgs()) {
3052 // But we can still look for an explicit specialization.
3053 if (FunctionDecl *ExplicitSpec
3054 = S.ResolveSingleFunctionTemplateSpecialization(Ovl))
3055 return GetTypeOfFunction(S, R, ExplicitSpec);
3061 // Gather the explicit template arguments, if any.
3062 TemplateArgumentListInfo ExplicitTemplateArgs;
3063 if (Ovl->hasExplicitTemplateArgs())
3064 Ovl->getExplicitTemplateArgs().copyInto(ExplicitTemplateArgs);
3066 for (UnresolvedSetIterator I = Ovl->decls_begin(),
3067 E = Ovl->decls_end(); I != E; ++I) {
3068 NamedDecl *D = (*I)->getUnderlyingDecl();
3070 if (FunctionTemplateDecl *FunTmpl = dyn_cast<FunctionTemplateDecl>(D)) {
3071 // - If the argument is an overload set containing one or more
3072 // function templates, the parameter is treated as a
3073 // non-deduced context.
3074 if (!Ovl->hasExplicitTemplateArgs())
3077 // Otherwise, see if we can resolve a function type
3078 FunctionDecl *Specialization = nullptr;
3079 TemplateDeductionInfo Info(Ovl->getNameLoc());
3080 if (S.DeduceTemplateArguments(FunTmpl, &ExplicitTemplateArgs,
3081 Specialization, Info))
3087 FunctionDecl *Fn = cast<FunctionDecl>(D);
3088 QualType ArgType = GetTypeOfFunction(S, R, Fn);
3089 if (ArgType.isNull()) continue;
3091 // Function-to-pointer conversion.
3092 if (!ParamWasReference && ParamType->isPointerType() &&
3093 ArgType->isFunctionType())
3094 ArgType = S.Context.getPointerType(ArgType);
3096 // - If the argument is an overload set (not containing function
3097 // templates), trial argument deduction is attempted using each
3098 // of the members of the set. If deduction succeeds for only one
3099 // of the overload set members, that member is used as the
3100 // argument value for the deduction. If deduction succeeds for
3101 // more than one member of the overload set the parameter is
3102 // treated as a non-deduced context.
3104 // We do all of this in a fresh context per C++0x [temp.deduct.type]p2:
3105 // Type deduction is done independently for each P/A pair, and
3106 // the deduced template argument values are then combined.
3107 // So we do not reject deductions which were made elsewhere.
3108 SmallVector<DeducedTemplateArgument, 8>
3109 Deduced(TemplateParams->size());
3110 TemplateDeductionInfo Info(Ovl->getNameLoc());
3111 Sema::TemplateDeductionResult Result
3112 = DeduceTemplateArgumentsByTypeMatch(S, TemplateParams, ParamType,
3113 ArgType, Info, Deduced, TDF);
3114 if (Result) continue;
3115 if (!Match.isNull()) return QualType();
3122 /// \brief Perform the adjustments to the parameter and argument types
3123 /// described in C++ [temp.deduct.call].
3125 /// \returns true if the caller should not attempt to perform any template
3126 /// argument deduction based on this P/A pair because the argument is an
3127 /// overloaded function set that could not be resolved.
3128 static bool AdjustFunctionParmAndArgTypesForDeduction(Sema &S,
3129 TemplateParameterList *TemplateParams,
3130 QualType &ParamType,
3134 // C++0x [temp.deduct.call]p3:
3135 // If P is a cv-qualified type, the top level cv-qualifiers of P's type
3136 // are ignored for type deduction.
3137 if (ParamType.hasQualifiers())
3138 ParamType = ParamType.getUnqualifiedType();
3139 const ReferenceType *ParamRefType = ParamType->getAs<ReferenceType>();
3141 QualType PointeeType = ParamRefType->getPointeeType();
3143 // If the argument has incomplete array type, try to complete its type.
3144 if (ArgType->isIncompleteArrayType() && !S.RequireCompleteExprType(Arg, 0))
3145 ArgType = Arg->getType();
3147 // [C++0x] If P is an rvalue reference to a cv-unqualified
3148 // template parameter and the argument is an lvalue, the type
3149 // "lvalue reference to A" is used in place of A for type
3151 if (isa<RValueReferenceType>(ParamType)) {
3152 if (!PointeeType.getQualifiers() &&
3153 isa<TemplateTypeParmType>(PointeeType) &&
3154 Arg->Classify(S.Context).isLValue() &&
3155 Arg->getType() != S.Context.OverloadTy &&
3156 Arg->getType() != S.Context.BoundMemberTy)
3157 ArgType = S.Context.getLValueReferenceType(ArgType);
3160 // [...] If P is a reference type, the type referred to by P is used
3161 // for type deduction.
3162 ParamType = PointeeType;
3165 // Overload sets usually make this parameter an undeduced
3166 // context, but there are sometimes special circumstances.
3167 if (ArgType == S.Context.OverloadTy) {
3168 ArgType = ResolveOverloadForDeduction(S, TemplateParams,
3170 ParamRefType != nullptr);
3171 if (ArgType.isNull())
3176 // C++0x [temp.deduct.call]p3:
3177 // [...] If P is of the form T&&, where T is a template parameter, and
3178 // the argument is an lvalue, the type A& is used in place of A for
3180 if (ParamRefType->isRValueReferenceType() &&
3181 ParamRefType->getAs<TemplateTypeParmType>() &&
3183 ArgType = S.Context.getLValueReferenceType(ArgType);
3185 // C++ [temp.deduct.call]p2:
3186 // If P is not a reference type:
3187 // - If A is an array type, the pointer type produced by the
3188 // array-to-pointer standard conversion (4.2) is used in place of
3189 // A for type deduction; otherwise,
3190 if (ArgType->isArrayType())
3191 ArgType = S.Context.getArrayDecayedType(ArgType);
3192 // - If A is a function type, the pointer type produced by the
3193 // function-to-pointer standard conversion (4.3) is used in place
3194 // of A for type deduction; otherwise,
3195 else if (ArgType->isFunctionType())
3196 ArgType = S.Context.getPointerType(ArgType);
3198 // - If A is a cv-qualified type, the top level cv-qualifiers of A's
3199 // type are ignored for type deduction.
3200 ArgType = ArgType.getUnqualifiedType();
3204 // C++0x [temp.deduct.call]p4:
3205 // In general, the deduction process attempts to find template argument
3206 // values that will make the deduced A identical to A (after the type A
3207 // is transformed as described above). [...]
3208 TDF = TDF_SkipNonDependent;
3210 // - If the original P is a reference type, the deduced A (i.e., the
3211 // type referred to by the reference) can be more cv-qualified than
3212 // the transformed A.
3214 TDF |= TDF_ParamWithReferenceType;
3215 // - The transformed A can be another pointer or pointer to member
3216 // type that can be converted to the deduced A via a qualification
3217 // conversion (4.4).
3218 if (ArgType->isPointerType() || ArgType->isMemberPointerType() ||
3219 ArgType->isObjCObjectPointerType())
3220 TDF |= TDF_IgnoreQualifiers;
3221 // - If P is a class and P has the form simple-template-id, then the
3222 // transformed A can be a derived class of the deduced A. Likewise,
3223 // if P is a pointer to a class of the form simple-template-id, the
3224 // transformed A can be a pointer to a derived class pointed to by
3226 if (isSimpleTemplateIdType(ParamType) ||
3227 (isa<PointerType>(ParamType) &&
3228 isSimpleTemplateIdType(
3229 ParamType->getAs<PointerType>()->getPointeeType())))
3230 TDF |= TDF_DerivedClass;
3236 hasDeducibleTemplateParameters(Sema &S, FunctionTemplateDecl *FunctionTemplate,
3239 /// \brief Perform template argument deduction by matching a parameter type
3240 /// against a single expression, where the expression is an element of
3241 /// an initializer list that was originally matched against a parameter
3242 /// of type \c initializer_list\<ParamType\>.
3243 static Sema::TemplateDeductionResult
3244 DeduceTemplateArgumentByListElement(Sema &S,
3245 TemplateParameterList *TemplateParams,
3246 QualType ParamType, Expr *Arg,
3247 TemplateDeductionInfo &Info,
3248 SmallVectorImpl<DeducedTemplateArgument> &Deduced,
3250 // Handle the case where an init list contains another init list as the
3252 if (InitListExpr *ILE = dyn_cast<InitListExpr>(Arg)) {
3254 if (!S.isStdInitializerList(ParamType.getNonReferenceType(), &X))
3255 return Sema::TDK_Success; // Just ignore this expression.
3257 // Recurse down into the init list.
3258 for (unsigned i = 0, e = ILE->getNumInits(); i < e; ++i) {
3259 if (Sema::TemplateDeductionResult Result =
3260 DeduceTemplateArgumentByListElement(S, TemplateParams, X,
3262 Info, Deduced, TDF))
3265 return Sema::TDK_Success;
3268 // For all other cases, just match by type.
3269 QualType ArgType = Arg->getType();
3270 if (AdjustFunctionParmAndArgTypesForDeduction(S, TemplateParams, ParamType,
3271 ArgType, Arg, TDF)) {
3272 Info.Expression = Arg;
3273 return Sema::TDK_FailedOverloadResolution;
3275 return DeduceTemplateArgumentsByTypeMatch(S, TemplateParams, ParamType,
3276 ArgType, Info, Deduced, TDF);
3279 /// \brief Perform template argument deduction from a function call
3280 /// (C++ [temp.deduct.call]).
3282 /// \param FunctionTemplate the function template for which we are performing
3283 /// template argument deduction.
3285 /// \param ExplicitTemplateArgs the explicit template arguments provided
3288 /// \param Args the function call arguments
3290 /// \param Specialization if template argument deduction was successful,
3291 /// this will be set to the function template specialization produced by
3292 /// template argument deduction.
3294 /// \param Info the argument will be updated to provide additional information
3295 /// about template argument deduction.
3297 /// \returns the result of template argument deduction.
3298 Sema::TemplateDeductionResult Sema::DeduceTemplateArguments(
3299 FunctionTemplateDecl *FunctionTemplate,
3300 TemplateArgumentListInfo *ExplicitTemplateArgs, ArrayRef<Expr *> Args,
3301 FunctionDecl *&Specialization, TemplateDeductionInfo &Info) {
3302 if (FunctionTemplate->isInvalidDecl())
3305 FunctionDecl *Function = FunctionTemplate->getTemplatedDecl();
3307 // C++ [temp.deduct.call]p1:
3308 // Template argument deduction is done by comparing each function template
3309 // parameter type (call it P) with the type of the corresponding argument
3310 // of the call (call it A) as described below.
3311 unsigned CheckArgs = Args.size();
3312 if (Args.size() < Function->getMinRequiredArguments())
3313 return TDK_TooFewArguments;
3314 else if (Args.size() > Function->getNumParams()) {
3315 const FunctionProtoType *Proto
3316 = Function->getType()->getAs<FunctionProtoType>();
3317 if (Proto->isTemplateVariadic())
3319 else if (Proto->isVariadic())
3320 CheckArgs = Function->getNumParams();
3322 return TDK_TooManyArguments;
3325 // The types of the parameters from which we will perform template argument
3327 LocalInstantiationScope InstScope(*this);
3328 TemplateParameterList *TemplateParams
3329 = FunctionTemplate->getTemplateParameters();
3330 SmallVector<DeducedTemplateArgument, 4> Deduced;
3331 SmallVector<QualType, 4> ParamTypes;
3332 unsigned NumExplicitlySpecified = 0;
3333 if (ExplicitTemplateArgs) {
3334 TemplateDeductionResult Result =
3335 SubstituteExplicitTemplateArguments(FunctionTemplate,
3336 *ExplicitTemplateArgs,
3344 NumExplicitlySpecified = Deduced.size();
3346 // Just fill in the parameter types from the function declaration.
3347 for (unsigned I = 0, N = Function->getNumParams(); I != N; ++I)
3348 ParamTypes.push_back(Function->getParamDecl(I)->getType());
3351 // Deduce template arguments from the function parameters.
3352 Deduced.resize(TemplateParams->size());
3353 unsigned ArgIdx = 0;
3354 SmallVector<OriginalCallArg, 4> OriginalCallArgs;
3355 for (unsigned ParamIdx = 0, NumParams = ParamTypes.size();
3356 ParamIdx != NumParams; ++ParamIdx) {
3357 QualType OrigParamType = ParamTypes[ParamIdx];
3358 QualType ParamType = OrigParamType;
3360 const PackExpansionType *ParamExpansion
3361 = dyn_cast<PackExpansionType>(ParamType);
3362 if (!ParamExpansion) {
3363 // Simple case: matching a function parameter to a function argument.
3364 if (ArgIdx >= CheckArgs)
3367 Expr *Arg = Args[ArgIdx++];
3368 QualType ArgType = Arg->getType();
3371 if (AdjustFunctionParmAndArgTypesForDeduction(*this, TemplateParams,
3372 ParamType, ArgType, Arg,
3376 // If we have nothing to deduce, we're done.
3377 if (!hasDeducibleTemplateParameters(*this, FunctionTemplate, ParamType))
3380 // If the argument is an initializer list ...
3381 if (InitListExpr *ILE = dyn_cast<InitListExpr>(Arg)) {
3382 // ... then the parameter is an undeduced context, unless the parameter
3383 // type is (reference to cv) std::initializer_list<P'>, in which case
3384 // deduction is done for each element of the initializer list, and the
3385 // result is the deduced type if it's the same for all elements.
3387 // Removing references was already done.
3388 if (!isStdInitializerList(ParamType, &X))
3391 for (unsigned i = 0, e = ILE->getNumInits(); i < e; ++i) {
3392 if (TemplateDeductionResult Result =
3393 DeduceTemplateArgumentByListElement(*this, TemplateParams, X,
3395 Info, Deduced, TDF))
3398 // Don't track the argument type, since an initializer list has none.
3402 // Keep track of the argument type and corresponding parameter index,
3403 // so we can check for compatibility between the deduced A and A.
3404 OriginalCallArgs.push_back(OriginalCallArg(OrigParamType, ArgIdx-1,
3407 if (TemplateDeductionResult Result
3408 = DeduceTemplateArgumentsByTypeMatch(*this, TemplateParams,
3410 Info, Deduced, TDF))
3416 // C++0x [temp.deduct.call]p1:
3417 // For a function parameter pack that occurs at the end of the
3418 // parameter-declaration-list, the type A of each remaining argument of
3419 // the call is compared with the type P of the declarator-id of the
3420 // function parameter pack. Each comparison deduces template arguments
3421 // for subsequent positions in the template parameter packs expanded by
3422 // the function parameter pack. For a function parameter pack that does
3423 // not occur at the end of the parameter-declaration-list, the type of
3424 // the parameter pack is a non-deduced context.
3425 if (ParamIdx + 1 < NumParams)
3428 QualType ParamPattern = ParamExpansion->getPattern();
3429 PackDeductionScope PackScope(*this, TemplateParams, Deduced, Info,
3432 bool HasAnyArguments = false;
3433 for (; ArgIdx < Args.size(); ++ArgIdx) {
3434 HasAnyArguments = true;
3436 QualType OrigParamType = ParamPattern;
3437 ParamType = OrigParamType;
3438 Expr *Arg = Args[ArgIdx];
3439 QualType ArgType = Arg->getType();
3442 if (AdjustFunctionParmAndArgTypesForDeduction(*this, TemplateParams,
3443 ParamType, ArgType, Arg,
3445 // We can't actually perform any deduction for this argument, so stop
3446 // deduction at this point.
3451 // As above, initializer lists need special handling.
3452 if (InitListExpr *ILE = dyn_cast<InitListExpr>(Arg)) {
3454 if (!isStdInitializerList(ParamType, &X)) {
3459 for (unsigned i = 0, e = ILE->getNumInits(); i < e; ++i) {
3460 if (TemplateDeductionResult Result =
3461 DeduceTemplateArgumentsByTypeMatch(*this, TemplateParams, X,
3462 ILE->getInit(i)->getType(),
3463 Info, Deduced, TDF))
3468 // Keep track of the argument type and corresponding argument index,
3469 // so we can check for compatibility between the deduced A and A.
3470 if (hasDeducibleTemplateParameters(*this, FunctionTemplate, ParamType))
3471 OriginalCallArgs.push_back(OriginalCallArg(OrigParamType, ArgIdx,
3474 if (TemplateDeductionResult Result
3475 = DeduceTemplateArgumentsByTypeMatch(*this, TemplateParams,
3476 ParamType, ArgType, Info,
3481 PackScope.nextPackElement();
3484 // Build argument packs for each of the parameter packs expanded by this
3486 if (auto Result = PackScope.finish(HasAnyArguments))
3489 // After we've matching against a parameter pack, we're done.
3493 return FinishTemplateArgumentDeduction(FunctionTemplate, Deduced,
3494 NumExplicitlySpecified, Specialization,
3495 Info, &OriginalCallArgs);
3498 QualType Sema::adjustCCAndNoReturn(QualType ArgFunctionType,
3499 QualType FunctionType) {
3500 if (ArgFunctionType.isNull())
3501 return ArgFunctionType;
3503 const FunctionProtoType *FunctionTypeP =
3504 FunctionType->castAs<FunctionProtoType>();
3505 CallingConv CC = FunctionTypeP->getCallConv();
3506 bool NoReturn = FunctionTypeP->getNoReturnAttr();
3507 const FunctionProtoType *ArgFunctionTypeP =
3508 ArgFunctionType->getAs<FunctionProtoType>();
3509 if (ArgFunctionTypeP->getCallConv() == CC &&
3510 ArgFunctionTypeP->getNoReturnAttr() == NoReturn)
3511 return ArgFunctionType;
3513 FunctionType::ExtInfo EI = ArgFunctionTypeP->getExtInfo().withCallingConv(CC);
3514 EI = EI.withNoReturn(NoReturn);
3516 cast<FunctionProtoType>(Context.adjustFunctionType(ArgFunctionTypeP, EI));
3517 return QualType(ArgFunctionTypeP, 0);
3520 /// \brief Deduce template arguments when taking the address of a function
3521 /// template (C++ [temp.deduct.funcaddr]) or matching a specialization to
3524 /// \param FunctionTemplate the function template for which we are performing
3525 /// template argument deduction.
3527 /// \param ExplicitTemplateArgs the explicitly-specified template
3530 /// \param ArgFunctionType the function type that will be used as the
3531 /// "argument" type (A) when performing template argument deduction from the
3532 /// function template's function type. This type may be NULL, if there is no
3533 /// argument type to compare against, in C++0x [temp.arg.explicit]p3.
3535 /// \param Specialization if template argument deduction was successful,
3536 /// this will be set to the function template specialization produced by
3537 /// template argument deduction.
3539 /// \param Info the argument will be updated to provide additional information
3540 /// about template argument deduction.
3542 /// \returns the result of template argument deduction.
3543 Sema::TemplateDeductionResult
3544 Sema::DeduceTemplateArguments(FunctionTemplateDecl *FunctionTemplate,
3545 TemplateArgumentListInfo *ExplicitTemplateArgs,
3546 QualType ArgFunctionType,
3547 FunctionDecl *&Specialization,
3548 TemplateDeductionInfo &Info,
3549 bool InOverloadResolution) {
3550 if (FunctionTemplate->isInvalidDecl())
3553 FunctionDecl *Function = FunctionTemplate->getTemplatedDecl();
3554 TemplateParameterList *TemplateParams
3555 = FunctionTemplate->getTemplateParameters();
3556 QualType FunctionType = Function->getType();
3557 if (!InOverloadResolution)
3558 ArgFunctionType = adjustCCAndNoReturn(ArgFunctionType, FunctionType);
3560 // Substitute any explicit template arguments.
3561 LocalInstantiationScope InstScope(*this);
3562 SmallVector<DeducedTemplateArgument, 4> Deduced;
3563 unsigned NumExplicitlySpecified = 0;
3564 SmallVector<QualType, 4> ParamTypes;
3565 if (ExplicitTemplateArgs) {
3566 if (TemplateDeductionResult Result
3567 = SubstituteExplicitTemplateArguments(FunctionTemplate,
3568 *ExplicitTemplateArgs,
3569 Deduced, ParamTypes,
3570 &FunctionType, Info))
3573 NumExplicitlySpecified = Deduced.size();
3576 // Unevaluated SFINAE context.
3577 EnterExpressionEvaluationContext Unevaluated(*this, Sema::Unevaluated);
3578 SFINAETrap Trap(*this);
3580 Deduced.resize(TemplateParams->size());
3582 // If the function has a deduced return type, substitute it for a dependent
3583 // type so that we treat it as a non-deduced context in what follows.
3584 bool HasDeducedReturnType = false;
3585 if (getLangOpts().CPlusPlus14 && InOverloadResolution &&
3586 Function->getReturnType()->getContainedAutoType()) {
3587 FunctionType = SubstAutoType(FunctionType, Context.DependentTy);
3588 HasDeducedReturnType = true;
3591 if (!ArgFunctionType.isNull()) {
3592 unsigned TDF = TDF_TopLevelParameterTypeList;
3593 if (InOverloadResolution) TDF |= TDF_InOverloadResolution;
3594 // Deduce template arguments from the function type.
3595 if (TemplateDeductionResult Result
3596 = DeduceTemplateArgumentsByTypeMatch(*this, TemplateParams,
3597 FunctionType, ArgFunctionType,
3598 Info, Deduced, TDF))
3602 if (TemplateDeductionResult Result
3603 = FinishTemplateArgumentDeduction(FunctionTemplate, Deduced,
3604 NumExplicitlySpecified,
3605 Specialization, Info))
3608 // If the function has a deduced return type, deduce it now, so we can check
3609 // that the deduced function type matches the requested type.
3610 if (HasDeducedReturnType &&
3611 Specialization->getReturnType()->isUndeducedType() &&
3612 DeduceReturnType(Specialization, Info.getLocation(), false))
3613 return TDK_MiscellaneousDeductionFailure;
3615 // If the requested function type does not match the actual type of the
3616 // specialization with respect to arguments of compatible pointer to function
3617 // types, template argument deduction fails.
3618 if (!ArgFunctionType.isNull()) {
3619 if (InOverloadResolution && !isSameOrCompatibleFunctionType(
3620 Context.getCanonicalType(Specialization->getType()),
3621 Context.getCanonicalType(ArgFunctionType)))
3622 return TDK_MiscellaneousDeductionFailure;
3623 else if(!InOverloadResolution &&
3624 !Context.hasSameType(Specialization->getType(), ArgFunctionType))
3625 return TDK_MiscellaneousDeductionFailure;
3631 /// \brief Given a function declaration (e.g. a generic lambda conversion
3632 /// function) that contains an 'auto' in its result type, substitute it
3633 /// with TypeToReplaceAutoWith. Be careful to pass in the type you want
3634 /// to replace 'auto' with and not the actual result type you want
3635 /// to set the function to.
3637 SubstAutoWithinFunctionReturnType(FunctionDecl *F,
3638 QualType TypeToReplaceAutoWith, Sema &S) {
3639 assert(!TypeToReplaceAutoWith->getContainedAutoType());
3640 QualType AutoResultType = F->getReturnType();
3641 assert(AutoResultType->getContainedAutoType());
3642 QualType DeducedResultType = S.SubstAutoType(AutoResultType,
3643 TypeToReplaceAutoWith);
3644 S.Context.adjustDeducedFunctionResultType(F, DeducedResultType);
3647 /// \brief Given a specialized conversion operator of a generic lambda
3648 /// create the corresponding specializations of the call operator and
3649 /// the static-invoker. If the return type of the call operator is auto,
3650 /// deduce its return type and check if that matches the
3651 /// return type of the destination function ptr.
3653 static inline Sema::TemplateDeductionResult
3654 SpecializeCorrespondingLambdaCallOperatorAndInvoker(
3655 CXXConversionDecl *ConversionSpecialized,
3656 SmallVectorImpl<DeducedTemplateArgument> &DeducedArguments,
3657 QualType ReturnTypeOfDestFunctionPtr,
3658 TemplateDeductionInfo &TDInfo,
3661 CXXRecordDecl *LambdaClass = ConversionSpecialized->getParent();
3662 assert(LambdaClass && LambdaClass->isGenericLambda());
3664 CXXMethodDecl *CallOpGeneric = LambdaClass->getLambdaCallOperator();
3665 QualType CallOpResultType = CallOpGeneric->getReturnType();
3666 const bool GenericLambdaCallOperatorHasDeducedReturnType =
3667 CallOpResultType->getContainedAutoType();
3669 FunctionTemplateDecl *CallOpTemplate =
3670 CallOpGeneric->getDescribedFunctionTemplate();
3672 FunctionDecl *CallOpSpecialized = nullptr;
3673 // Use the deduced arguments of the conversion function, to specialize our
3674 // generic lambda's call operator.
3675 if (Sema::TemplateDeductionResult Result
3676 = S.FinishTemplateArgumentDeduction(CallOpTemplate,
3678 0, CallOpSpecialized, TDInfo))
3681 // If we need to deduce the return type, do so (instantiates the callop).
3682 if (GenericLambdaCallOperatorHasDeducedReturnType &&
3683 CallOpSpecialized->getReturnType()->isUndeducedType())
3684 S.DeduceReturnType(CallOpSpecialized,
3685 CallOpSpecialized->getPointOfInstantiation(),
3688 // Check to see if the return type of the destination ptr-to-function
3689 // matches the return type of the call operator.
3690 if (!S.Context.hasSameType(CallOpSpecialized->getReturnType(),
3691 ReturnTypeOfDestFunctionPtr))
3692 return Sema::TDK_NonDeducedMismatch;
3693 // Since we have succeeded in matching the source and destination
3694 // ptr-to-functions (now including return type), and have successfully
3695 // specialized our corresponding call operator, we are ready to
3696 // specialize the static invoker with the deduced arguments of our
3698 FunctionDecl *InvokerSpecialized = nullptr;
3699 FunctionTemplateDecl *InvokerTemplate = LambdaClass->
3700 getLambdaStaticInvoker()->getDescribedFunctionTemplate();
3702 Sema::TemplateDeductionResult LLVM_ATTRIBUTE_UNUSED Result
3703 = S.FinishTemplateArgumentDeduction(InvokerTemplate, DeducedArguments, 0,
3704 InvokerSpecialized, TDInfo);
3705 assert(Result == Sema::TDK_Success &&
3706 "If the call operator succeeded so should the invoker!");
3707 // Set the result type to match the corresponding call operator
3708 // specialization's result type.
3709 if (GenericLambdaCallOperatorHasDeducedReturnType &&
3710 InvokerSpecialized->getReturnType()->isUndeducedType()) {
3711 // Be sure to get the type to replace 'auto' with and not
3712 // the full result type of the call op specialization
3713 // to substitute into the 'auto' of the invoker and conversion
3716 // int* (*fp)(int*) = [](auto* a) -> auto* { return a; };
3717 // We don't want to subst 'int*' into 'auto' to get int**.
3719 QualType TypeToReplaceAutoWith = CallOpSpecialized->getReturnType()
3720 ->getContainedAutoType()
3722 SubstAutoWithinFunctionReturnType(InvokerSpecialized,
3723 TypeToReplaceAutoWith, S);
3724 SubstAutoWithinFunctionReturnType(ConversionSpecialized,
3725 TypeToReplaceAutoWith, S);
3728 // Ensure that static invoker doesn't have a const qualifier.
3729 // FIXME: When creating the InvokerTemplate in SemaLambda.cpp
3730 // do not use the CallOperator's TypeSourceInfo which allows
3731 // the const qualifier to leak through.
3732 const FunctionProtoType *InvokerFPT = InvokerSpecialized->
3733 getType().getTypePtr()->castAs<FunctionProtoType>();
3734 FunctionProtoType::ExtProtoInfo EPI = InvokerFPT->getExtProtoInfo();
3736 InvokerSpecialized->setType(S.Context.getFunctionType(
3737 InvokerFPT->getReturnType(), InvokerFPT->getParamTypes(), EPI));
3738 return Sema::TDK_Success;
3740 /// \brief Deduce template arguments for a templated conversion
3741 /// function (C++ [temp.deduct.conv]) and, if successful, produce a
3742 /// conversion function template specialization.
3743 Sema::TemplateDeductionResult
3744 Sema::DeduceTemplateArguments(FunctionTemplateDecl *ConversionTemplate,
3746 CXXConversionDecl *&Specialization,
3747 TemplateDeductionInfo &Info) {
3748 if (ConversionTemplate->isInvalidDecl())
3751 CXXConversionDecl *ConversionGeneric
3752 = cast<CXXConversionDecl>(ConversionTemplate->getTemplatedDecl());
3754 QualType FromType = ConversionGeneric->getConversionType();
3756 // Canonicalize the types for deduction.
3757 QualType P = Context.getCanonicalType(FromType);
3758 QualType A = Context.getCanonicalType(ToType);
3760 // C++0x [temp.deduct.conv]p2:
3761 // If P is a reference type, the type referred to by P is used for
3763 if (const ReferenceType *PRef = P->getAs<ReferenceType>())
3764 P = PRef->getPointeeType();
3766 // C++0x [temp.deduct.conv]p4:
3767 // [...] If A is a reference type, the type referred to by A is used
3768 // for type deduction.
3769 if (const ReferenceType *ARef = A->getAs<ReferenceType>())
3770 A = ARef->getPointeeType().getUnqualifiedType();
3771 // C++ [temp.deduct.conv]p3:
3773 // If A is not a reference type:
3775 assert(!A->isReferenceType() && "Reference types were handled above");
3777 // - If P is an array type, the pointer type produced by the
3778 // array-to-pointer standard conversion (4.2) is used in place
3779 // of P for type deduction; otherwise,
3780 if (P->isArrayType())
3781 P = Context.getArrayDecayedType(P);
3782 // - If P is a function type, the pointer type produced by the
3783 // function-to-pointer standard conversion (4.3) is used in
3784 // place of P for type deduction; otherwise,
3785 else if (P->isFunctionType())
3786 P = Context.getPointerType(P);
3787 // - If P is a cv-qualified type, the top level cv-qualifiers of
3788 // P's type are ignored for type deduction.
3790 P = P.getUnqualifiedType();
3792 // C++0x [temp.deduct.conv]p4:
3793 // If A is a cv-qualified type, the top level cv-qualifiers of A's
3794 // type are ignored for type deduction. If A is a reference type, the type
3795 // referred to by A is used for type deduction.
3796 A = A.getUnqualifiedType();
3799 // Unevaluated SFINAE context.
3800 EnterExpressionEvaluationContext Unevaluated(*this, Sema::Unevaluated);
3801 SFINAETrap Trap(*this);
3803 // C++ [temp.deduct.conv]p1:
3804 // Template argument deduction is done by comparing the return
3805 // type of the template conversion function (call it P) with the
3806 // type that is required as the result of the conversion (call it
3807 // A) as described in 14.8.2.4.
3808 TemplateParameterList *TemplateParams
3809 = ConversionTemplate->getTemplateParameters();
3810 SmallVector<DeducedTemplateArgument, 4> Deduced;
3811 Deduced.resize(TemplateParams->size());
3813 // C++0x [temp.deduct.conv]p4:
3814 // In general, the deduction process attempts to find template
3815 // argument values that will make the deduced A identical to
3816 // A. However, there are two cases that allow a difference:
3818 // - If the original A is a reference type, A can be more
3819 // cv-qualified than the deduced A (i.e., the type referred to
3820 // by the reference)
3821 if (ToType->isReferenceType())
3822 TDF |= TDF_ParamWithReferenceType;
3823 // - The deduced A can be another pointer or pointer to member
3824 // type that can be converted to A via a qualification
3827 // (C++0x [temp.deduct.conv]p6 clarifies that this only happens when
3828 // both P and A are pointers or member pointers. In this case, we
3829 // just ignore cv-qualifiers completely).
3830 if ((P->isPointerType() && A->isPointerType()) ||
3831 (P->isMemberPointerType() && A->isMemberPointerType()))
3832 TDF |= TDF_IgnoreQualifiers;
3833 if (TemplateDeductionResult Result
3834 = DeduceTemplateArgumentsByTypeMatch(*this, TemplateParams,
3835 P, A, Info, Deduced, TDF))
3838 // Create an Instantiation Scope for finalizing the operator.
3839 LocalInstantiationScope InstScope(*this);
3840 // Finish template argument deduction.
3841 FunctionDecl *ConversionSpecialized = nullptr;
3842 TemplateDeductionResult Result
3843 = FinishTemplateArgumentDeduction(ConversionTemplate, Deduced, 0,
3844 ConversionSpecialized, Info);
3845 Specialization = cast_or_null<CXXConversionDecl>(ConversionSpecialized);
3847 // If the conversion operator is being invoked on a lambda closure to convert
3848 // to a ptr-to-function, use the deduced arguments from the conversion
3849 // function to specialize the corresponding call operator.
3850 // e.g., int (*fp)(int) = [](auto a) { return a; };
3851 if (Result == TDK_Success && isLambdaConversionOperator(ConversionGeneric)) {
3853 // Get the return type of the destination ptr-to-function we are converting
3854 // to. This is necessary for matching the lambda call operator's return
3855 // type to that of the destination ptr-to-function's return type.
3856 assert(A->isPointerType() &&
3857 "Can only convert from lambda to ptr-to-function");
3858 const FunctionType *ToFunType =
3859 A->getPointeeType().getTypePtr()->getAs<FunctionType>();
3860 const QualType DestFunctionPtrReturnType = ToFunType->getReturnType();
3862 // Create the corresponding specializations of the call operator and
3863 // the static-invoker; and if the return type is auto,
3864 // deduce the return type and check if it matches the
3865 // DestFunctionPtrReturnType.
3867 // auto L = [](auto a) { return f(a); };
3868 // int (*fp)(int) = L;
3869 // char (*fp2)(int) = L; <-- Not OK.
3871 Result = SpecializeCorrespondingLambdaCallOperatorAndInvoker(
3872 Specialization, Deduced, DestFunctionPtrReturnType,
3878 /// \brief Deduce template arguments for a function template when there is
3879 /// nothing to deduce against (C++0x [temp.arg.explicit]p3).
3881 /// \param FunctionTemplate the function template for which we are performing
3882 /// template argument deduction.
3884 /// \param ExplicitTemplateArgs the explicitly-specified template
3887 /// \param Specialization if template argument deduction was successful,
3888 /// this will be set to the function template specialization produced by
3889 /// template argument deduction.
3891 /// \param Info the argument will be updated to provide additional information
3892 /// about template argument deduction.
3894 /// \returns the result of template argument deduction.
3895 Sema::TemplateDeductionResult
3896 Sema::DeduceTemplateArguments(FunctionTemplateDecl *FunctionTemplate,
3897 TemplateArgumentListInfo *ExplicitTemplateArgs,
3898 FunctionDecl *&Specialization,
3899 TemplateDeductionInfo &Info,
3900 bool InOverloadResolution) {
3901 return DeduceTemplateArguments(FunctionTemplate, ExplicitTemplateArgs,
3902 QualType(), Specialization, Info,
3903 InOverloadResolution);
3907 /// Substitute the 'auto' type specifier within a type for a given replacement
3909 class SubstituteAutoTransform :
3910 public TreeTransform<SubstituteAutoTransform> {
3911 QualType Replacement;
3913 SubstituteAutoTransform(Sema &SemaRef, QualType Replacement)
3914 : TreeTransform<SubstituteAutoTransform>(SemaRef),
3915 Replacement(Replacement) {}
3917 QualType TransformAutoType(TypeLocBuilder &TLB, AutoTypeLoc TL) {
3918 // If we're building the type pattern to deduce against, don't wrap the
3919 // substituted type in an AutoType. Certain template deduction rules
3920 // apply only when a template type parameter appears directly (and not if
3921 // the parameter is found through desugaring). For instance:
3922 // auto &&lref = lvalue;
3923 // must transform into "rvalue reference to T" not "rvalue reference to
3924 // auto type deduced as T" in order for [temp.deduct.call]p3 to apply.
3925 if (!Replacement.isNull() && isa<TemplateTypeParmType>(Replacement)) {
3926 QualType Result = Replacement;
3927 TemplateTypeParmTypeLoc NewTL =
3928 TLB.push<TemplateTypeParmTypeLoc>(Result);
3929 NewTL.setNameLoc(TL.getNameLoc());
3933 !Replacement.isNull() && Replacement->isDependentType();
3935 SemaRef.Context.getAutoType(Dependent ? QualType() : Replacement,
3936 TL.getTypePtr()->isDecltypeAuto(),
3938 AutoTypeLoc NewTL = TLB.push<AutoTypeLoc>(Result);
3939 NewTL.setNameLoc(TL.getNameLoc());
3944 ExprResult TransformLambdaExpr(LambdaExpr *E) {
3945 // Lambdas never need to be transformed.
3949 QualType Apply(TypeLoc TL) {
3950 // Create some scratch storage for the transformed type locations.
3951 // FIXME: We're just going to throw this information away. Don't build it.
3953 TLB.reserve(TL.getFullDataSize());
3954 return TransformType(TLB, TL);
3959 Sema::DeduceAutoResult
3960 Sema::DeduceAutoType(TypeSourceInfo *Type, Expr *&Init, QualType &Result) {
3961 return DeduceAutoType(Type->getTypeLoc(), Init, Result);
3964 /// \brief Deduce the type for an auto type-specifier (C++11 [dcl.spec.auto]p6)
3966 /// \param Type the type pattern using the auto type-specifier.
3967 /// \param Init the initializer for the variable whose type is to be deduced.
3968 /// \param Result if type deduction was successful, this will be set to the
3970 Sema::DeduceAutoResult
3971 Sema::DeduceAutoType(TypeLoc Type, Expr *&Init, QualType &Result) {
3972 if (Init->getType()->isNonOverloadPlaceholderType()) {
3973 ExprResult NonPlaceholder = CheckPlaceholderExpr(Init);
3974 if (NonPlaceholder.isInvalid())
3975 return DAR_FailedAlreadyDiagnosed;
3976 Init = NonPlaceholder.get();
3979 if (Init->isTypeDependent() || Type.getType()->isDependentType()) {
3980 Result = SubstituteAutoTransform(*this, Context.DependentTy).Apply(Type);
3981 assert(!Result.isNull() && "substituting DependentTy can't fail");
3982 return DAR_Succeeded;
3985 // If this is a 'decltype(auto)' specifier, do the decltype dance.
3986 // Since 'decltype(auto)' can only occur at the top of the type, we
3987 // don't need to go digging for it.
3988 if (const AutoType *AT = Type.getType()->getAs<AutoType>()) {
3989 if (AT->isDecltypeAuto()) {
3990 if (isa<InitListExpr>(Init)) {
3991 Diag(Init->getLocStart(), diag::err_decltype_auto_initializer_list);
3992 return DAR_FailedAlreadyDiagnosed;
3995 QualType Deduced = BuildDecltypeType(Init, Init->getLocStart(), false);
3996 // FIXME: Support a non-canonical deduced type for 'auto'.
3997 Deduced = Context.getCanonicalType(Deduced);
3998 Result = SubstituteAutoTransform(*this, Deduced).Apply(Type);
3999 if (Result.isNull())
4000 return DAR_FailedAlreadyDiagnosed;
4001 return DAR_Succeeded;
4005 SourceLocation Loc = Init->getExprLoc();
4007 LocalInstantiationScope InstScope(*this);
4009 // Build template<class TemplParam> void Func(FuncParam);
4010 TemplateTypeParmDecl *TemplParam =
4011 TemplateTypeParmDecl::Create(Context, nullptr, SourceLocation(), Loc, 0, 0,
4012 nullptr, false, false);
4013 QualType TemplArg = QualType(TemplParam->getTypeForDecl(), 0);
4014 NamedDecl *TemplParamPtr = TemplParam;
4015 FixedSizeTemplateParameterList<1> TemplateParams(Loc, Loc, &TemplParamPtr,
4018 QualType FuncParam = SubstituteAutoTransform(*this, TemplArg).Apply(Type);
4019 assert(!FuncParam.isNull() &&
4020 "substituting template parameter for 'auto' failed");
4022 // Deduce type of TemplParam in Func(Init)
4023 SmallVector<DeducedTemplateArgument, 1> Deduced;
4025 QualType InitType = Init->getType();
4028 TemplateDeductionInfo Info(Loc);
4030 InitListExpr *InitList = dyn_cast<InitListExpr>(Init);
4032 for (unsigned i = 0, e = InitList->getNumInits(); i < e; ++i) {
4033 if (DeduceTemplateArgumentByListElement(*this, &TemplateParams,
4035 InitList->getInit(i),
4036 Info, Deduced, TDF))
4040 if (AdjustFunctionParmAndArgTypesForDeduction(*this, &TemplateParams,
4041 FuncParam, InitType, Init,
4045 if (DeduceTemplateArgumentsByTypeMatch(*this, &TemplateParams, FuncParam,
4046 InitType, Info, Deduced, TDF))
4050 if (Deduced[0].getKind() != TemplateArgument::Type)
4053 QualType DeducedType = Deduced[0].getAsType();
4056 DeducedType = BuildStdInitializerList(DeducedType, Loc);
4057 if (DeducedType.isNull())
4058 return DAR_FailedAlreadyDiagnosed;
4061 Result = SubstituteAutoTransform(*this, DeducedType).Apply(Type);
4062 if (Result.isNull())
4063 return DAR_FailedAlreadyDiagnosed;
4065 // Check that the deduced argument type is compatible with the original
4066 // argument type per C++ [temp.deduct.call]p4.
4067 if (!InitList && !Result.isNull() &&
4068 CheckOriginalCallArgDeduction(*this,
4069 Sema::OriginalCallArg(FuncParam,0,InitType),
4071 Result = QualType();
4075 return DAR_Succeeded;
4078 QualType Sema::SubstAutoType(QualType TypeWithAuto,
4079 QualType TypeToReplaceAuto) {
4080 return SubstituteAutoTransform(*this, TypeToReplaceAuto).
4081 TransformType(TypeWithAuto);
4084 TypeSourceInfo* Sema::SubstAutoTypeSourceInfo(TypeSourceInfo *TypeWithAuto,
4085 QualType TypeToReplaceAuto) {
4086 return SubstituteAutoTransform(*this, TypeToReplaceAuto).
4087 TransformType(TypeWithAuto);
4090 void Sema::DiagnoseAutoDeductionFailure(VarDecl *VDecl, Expr *Init) {
4091 if (isa<InitListExpr>(Init))
4092 Diag(VDecl->getLocation(),
4093 VDecl->isInitCapture()
4094 ? diag::err_init_capture_deduction_failure_from_init_list
4095 : diag::err_auto_var_deduction_failure_from_init_list)
4096 << VDecl->getDeclName() << VDecl->getType() << Init->getSourceRange();
4098 Diag(VDecl->getLocation(),
4099 VDecl->isInitCapture() ? diag::err_init_capture_deduction_failure
4100 : diag::err_auto_var_deduction_failure)
4101 << VDecl->getDeclName() << VDecl->getType() << Init->getType()
4102 << Init->getSourceRange();
4105 bool Sema::DeduceReturnType(FunctionDecl *FD, SourceLocation Loc,
4107 assert(FD->getReturnType()->isUndeducedType());
4109 if (FD->getTemplateInstantiationPattern())
4110 InstantiateFunctionDefinition(Loc, FD);
4112 bool StillUndeduced = FD->getReturnType()->isUndeducedType();
4113 if (StillUndeduced && Diagnose && !FD->isInvalidDecl()) {
4114 Diag(Loc, diag::err_auto_fn_used_before_defined) << FD;
4115 Diag(FD->getLocation(), diag::note_callee_decl) << FD;
4118 return StillUndeduced;
4122 MarkUsedTemplateParameters(ASTContext &Ctx, QualType T,
4125 llvm::SmallBitVector &Deduced);
4127 /// \brief If this is a non-static member function,
4129 AddImplicitObjectParameterType(ASTContext &Context,
4130 CXXMethodDecl *Method,
4131 SmallVectorImpl<QualType> &ArgTypes) {
4132 // C++11 [temp.func.order]p3:
4133 // [...] The new parameter is of type "reference to cv A," where cv are
4134 // the cv-qualifiers of the function template (if any) and A is
4135 // the class of which the function template is a member.
4137 // The standard doesn't say explicitly, but we pick the appropriate kind of
4138 // reference type based on [over.match.funcs]p4.
4139 QualType ArgTy = Context.getTypeDeclType(Method->getParent());
4140 ArgTy = Context.getQualifiedType(ArgTy,
4141 Qualifiers::fromCVRMask(Method->getTypeQualifiers()));
4142 if (Method->getRefQualifier() == RQ_RValue)
4143 ArgTy = Context.getRValueReferenceType(ArgTy);
4145 ArgTy = Context.getLValueReferenceType(ArgTy);
4146 ArgTypes.push_back(ArgTy);
4149 /// \brief Determine whether the function template \p FT1 is at least as
4150 /// specialized as \p FT2.
4151 static bool isAtLeastAsSpecializedAs(Sema &S,
4153 FunctionTemplateDecl *FT1,
4154 FunctionTemplateDecl *FT2,
4155 TemplatePartialOrderingContext TPOC,
4156 unsigned NumCallArguments1,
4157 SmallVectorImpl<RefParamPartialOrderingComparison> *RefParamComparisons) {
4158 FunctionDecl *FD1 = FT1->getTemplatedDecl();
4159 FunctionDecl *FD2 = FT2->getTemplatedDecl();
4160 const FunctionProtoType *Proto1 = FD1->getType()->getAs<FunctionProtoType>();
4161 const FunctionProtoType *Proto2 = FD2->getType()->getAs<FunctionProtoType>();
4163 assert(Proto1 && Proto2 && "Function templates must have prototypes");
4164 TemplateParameterList *TemplateParams = FT2->getTemplateParameters();
4165 SmallVector<DeducedTemplateArgument, 4> Deduced;
4166 Deduced.resize(TemplateParams->size());
4168 // C++0x [temp.deduct.partial]p3:
4169 // The types used to determine the ordering depend on the context in which
4170 // the partial ordering is done:
4171 TemplateDeductionInfo Info(Loc);
4172 SmallVector<QualType, 4> Args2;
4175 // - In the context of a function call, the function parameter types are
4177 CXXMethodDecl *Method1 = dyn_cast<CXXMethodDecl>(FD1);
4178 CXXMethodDecl *Method2 = dyn_cast<CXXMethodDecl>(FD2);
4180 // C++11 [temp.func.order]p3:
4181 // [...] If only one of the function templates is a non-static
4182 // member, that function template is considered to have a new
4183 // first parameter inserted in its function parameter list. The
4184 // new parameter is of type "reference to cv A," where cv are
4185 // the cv-qualifiers of the function template (if any) and A is
4186 // the class of which the function template is a member.
4188 // Note that we interpret this to mean "if one of the function
4189 // templates is a non-static member and the other is a non-member";
4190 // otherwise, the ordering rules for static functions against non-static
4191 // functions don't make any sense.
4193 // C++98/03 doesn't have this provision but we've extended DR532 to cover
4194 // it as wording was broken prior to it.
4195 SmallVector<QualType, 4> Args1;
4197 unsigned NumComparedArguments = NumCallArguments1;
4199 if (!Method2 && Method1 && !Method1->isStatic()) {
4200 // Compare 'this' from Method1 against first parameter from Method2.
4201 AddImplicitObjectParameterType(S.Context, Method1, Args1);
4202 ++NumComparedArguments;
4203 } else if (!Method1 && Method2 && !Method2->isStatic()) {
4204 // Compare 'this' from Method2 against first parameter from Method1.
4205 AddImplicitObjectParameterType(S.Context, Method2, Args2);
4208 Args1.insert(Args1.end(), Proto1->param_type_begin(),
4209 Proto1->param_type_end());
4210 Args2.insert(Args2.end(), Proto2->param_type_begin(),
4211 Proto2->param_type_end());
4213 // C++ [temp.func.order]p5:
4214 // The presence of unused ellipsis and default arguments has no effect on
4215 // the partial ordering of function templates.
4216 if (Args1.size() > NumComparedArguments)
4217 Args1.resize(NumComparedArguments);
4218 if (Args2.size() > NumComparedArguments)
4219 Args2.resize(NumComparedArguments);
4220 if (DeduceTemplateArguments(S, TemplateParams, Args2.data(), Args2.size(),
4221 Args1.data(), Args1.size(), Info, Deduced,
4222 TDF_None, /*PartialOrdering=*/true,
4223 RefParamComparisons))
4229 case TPOC_Conversion:
4230 // - In the context of a call to a conversion operator, the return types
4231 // of the conversion function templates are used.
4232 if (DeduceTemplateArgumentsByTypeMatch(
4233 S, TemplateParams, Proto2->getReturnType(), Proto1->getReturnType(),
4234 Info, Deduced, TDF_None,
4235 /*PartialOrdering=*/true, RefParamComparisons))
4240 // - In other contexts (14.6.6.2) the function template's function type
4242 if (DeduceTemplateArgumentsByTypeMatch(S, TemplateParams,
4243 FD2->getType(), FD1->getType(),
4244 Info, Deduced, TDF_None,
4245 /*PartialOrdering=*/true,
4246 RefParamComparisons))
4251 // C++0x [temp.deduct.partial]p11:
4252 // In most cases, all template parameters must have values in order for
4253 // deduction to succeed, but for partial ordering purposes a template
4254 // parameter may remain without a value provided it is not used in the
4255 // types being used for partial ordering. [ Note: a template parameter used
4256 // in a non-deduced context is considered used. -end note]
4257 unsigned ArgIdx = 0, NumArgs = Deduced.size();
4258 for (; ArgIdx != NumArgs; ++ArgIdx)
4259 if (Deduced[ArgIdx].isNull())
4262 if (ArgIdx == NumArgs) {
4263 // All template arguments were deduced. FT1 is at least as specialized
4268 // Figure out which template parameters were used.
4269 llvm::SmallBitVector UsedParameters(TemplateParams->size());
4272 for (unsigned I = 0, N = Args2.size(); I != N; ++I)
4273 ::MarkUsedTemplateParameters(S.Context, Args2[I], false,
4274 TemplateParams->getDepth(),
4278 case TPOC_Conversion:
4279 ::MarkUsedTemplateParameters(S.Context, Proto2->getReturnType(), false,
4280 TemplateParams->getDepth(), UsedParameters);
4284 ::MarkUsedTemplateParameters(S.Context, FD2->getType(), false,
4285 TemplateParams->getDepth(),
4290 for (; ArgIdx != NumArgs; ++ArgIdx)
4291 // If this argument had no value deduced but was used in one of the types
4292 // used for partial ordering, then deduction fails.
4293 if (Deduced[ArgIdx].isNull() && UsedParameters[ArgIdx])
4299 /// \brief Determine whether this a function template whose parameter-type-list
4300 /// ends with a function parameter pack.
4301 static bool isVariadicFunctionTemplate(FunctionTemplateDecl *FunTmpl) {
4302 FunctionDecl *Function = FunTmpl->getTemplatedDecl();
4303 unsigned NumParams = Function->getNumParams();
4307 ParmVarDecl *Last = Function->getParamDecl(NumParams - 1);
4308 if (!Last->isParameterPack())
4311 // Make sure that no previous parameter is a parameter pack.
4312 while (--NumParams > 0) {
4313 if (Function->getParamDecl(NumParams - 1)->isParameterPack())
4320 /// \brief Returns the more specialized function template according
4321 /// to the rules of function template partial ordering (C++ [temp.func.order]).
4323 /// \param FT1 the first function template
4325 /// \param FT2 the second function template
4327 /// \param TPOC the context in which we are performing partial ordering of
4328 /// function templates.
4330 /// \param NumCallArguments1 The number of arguments in the call to FT1, used
4331 /// only when \c TPOC is \c TPOC_Call.
4333 /// \param NumCallArguments2 The number of arguments in the call to FT2, used
4334 /// only when \c TPOC is \c TPOC_Call.
4336 /// \returns the more specialized function template. If neither
4337 /// template is more specialized, returns NULL.
4338 FunctionTemplateDecl *
4339 Sema::getMoreSpecializedTemplate(FunctionTemplateDecl *FT1,
4340 FunctionTemplateDecl *FT2,
4342 TemplatePartialOrderingContext TPOC,
4343 unsigned NumCallArguments1,
4344 unsigned NumCallArguments2) {
4345 SmallVector<RefParamPartialOrderingComparison, 4> RefParamComparisons;
4346 bool Better1 = isAtLeastAsSpecializedAs(*this, Loc, FT1, FT2, TPOC,
4347 NumCallArguments1, nullptr);
4348 bool Better2 = isAtLeastAsSpecializedAs(*this, Loc, FT2, FT1, TPOC,
4350 &RefParamComparisons);
4352 if (Better1 != Better2) // We have a clear winner
4353 return Better1? FT1 : FT2;
4355 if (!Better1 && !Better2) // Neither is better than the other
4358 // C++0x [temp.deduct.partial]p10:
4359 // If for each type being considered a given template is at least as
4360 // specialized for all types and more specialized for some set of types and
4361 // the other template is not more specialized for any types or is not at
4362 // least as specialized for any types, then the given template is more
4363 // specialized than the other template. Otherwise, neither template is more
4364 // specialized than the other.
4367 for (unsigned I = 0, N = RefParamComparisons.size(); I != N; ++I) {
4368 // C++0x [temp.deduct.partial]p9:
4369 // If, for a given type, deduction succeeds in both directions (i.e., the
4370 // types are identical after the transformations above) and both P and A
4371 // were reference types (before being replaced with the type referred to
4374 // -- if the type from the argument template was an lvalue reference
4375 // and the type from the parameter template was not, the argument
4376 // type is considered to be more specialized than the other;
4378 if (!RefParamComparisons[I].ArgIsRvalueRef &&
4379 RefParamComparisons[I].ParamIsRvalueRef) {
4384 } else if (!RefParamComparisons[I].ParamIsRvalueRef &&
4385 RefParamComparisons[I].ArgIsRvalueRef) {
4392 // -- if the type from the argument template is more cv-qualified than
4393 // the type from the parameter template (as described above), the
4394 // argument type is considered to be more specialized than the
4395 // other; otherwise,
4396 switch (RefParamComparisons[I].Qualifiers) {
4397 case NeitherMoreQualified:
4400 case ParamMoreQualified:
4406 case ArgMoreQualified:
4413 // -- neither type is more specialized than the other.
4416 assert(!(Better1 && Better2) && "Should have broken out in the loop above");
4422 // FIXME: This mimics what GCC implements, but doesn't match up with the
4423 // proposed resolution for core issue 692. This area needs to be sorted out,
4424 // but for now we attempt to maintain compatibility.
4425 bool Variadic1 = isVariadicFunctionTemplate(FT1);
4426 bool Variadic2 = isVariadicFunctionTemplate(FT2);
4427 if (Variadic1 != Variadic2)
4428 return Variadic1? FT2 : FT1;
4433 /// \brief Determine if the two templates are equivalent.
4434 static bool isSameTemplate(TemplateDecl *T1, TemplateDecl *T2) {
4441 return T1->getCanonicalDecl() == T2->getCanonicalDecl();
4444 /// \brief Retrieve the most specialized of the given function template
4445 /// specializations.
4447 /// \param SpecBegin the start iterator of the function template
4448 /// specializations that we will be comparing.
4450 /// \param SpecEnd the end iterator of the function template
4451 /// specializations, paired with \p SpecBegin.
4453 /// \param Loc the location where the ambiguity or no-specializations
4454 /// diagnostic should occur.
4456 /// \param NoneDiag partial diagnostic used to diagnose cases where there are
4457 /// no matching candidates.
4459 /// \param AmbigDiag partial diagnostic used to diagnose an ambiguity, if one
4462 /// \param CandidateDiag partial diagnostic used for each function template
4463 /// specialization that is a candidate in the ambiguous ordering. One parameter
4464 /// in this diagnostic should be unbound, which will correspond to the string
4465 /// describing the template arguments for the function template specialization.
4467 /// \returns the most specialized function template specialization, if
4468 /// found. Otherwise, returns SpecEnd.
4469 UnresolvedSetIterator Sema::getMostSpecialized(
4470 UnresolvedSetIterator SpecBegin, UnresolvedSetIterator SpecEnd,
4471 TemplateSpecCandidateSet &FailedCandidates,
4472 SourceLocation Loc, const PartialDiagnostic &NoneDiag,
4473 const PartialDiagnostic &AmbigDiag, const PartialDiagnostic &CandidateDiag,
4474 bool Complain, QualType TargetType) {
4475 if (SpecBegin == SpecEnd) {
4477 Diag(Loc, NoneDiag);
4478 FailedCandidates.NoteCandidates(*this, Loc);
4483 if (SpecBegin + 1 == SpecEnd)
4486 // Find the function template that is better than all of the templates it
4487 // has been compared to.
4488 UnresolvedSetIterator Best = SpecBegin;
4489 FunctionTemplateDecl *BestTemplate
4490 = cast<FunctionDecl>(*Best)->getPrimaryTemplate();
4491 assert(BestTemplate && "Not a function template specialization?");
4492 for (UnresolvedSetIterator I = SpecBegin + 1; I != SpecEnd; ++I) {
4493 FunctionTemplateDecl *Challenger
4494 = cast<FunctionDecl>(*I)->getPrimaryTemplate();
4495 assert(Challenger && "Not a function template specialization?");
4496 if (isSameTemplate(getMoreSpecializedTemplate(BestTemplate, Challenger,
4497 Loc, TPOC_Other, 0, 0),
4500 BestTemplate = Challenger;
4504 // Make sure that the "best" function template is more specialized than all
4506 bool Ambiguous = false;
4507 for (UnresolvedSetIterator I = SpecBegin; I != SpecEnd; ++I) {
4508 FunctionTemplateDecl *Challenger
4509 = cast<FunctionDecl>(*I)->getPrimaryTemplate();
4511 !isSameTemplate(getMoreSpecializedTemplate(BestTemplate, Challenger,
4512 Loc, TPOC_Other, 0, 0),
4520 // We found an answer. Return it.
4524 // Diagnose the ambiguity.
4526 Diag(Loc, AmbigDiag);
4528 // FIXME: Can we order the candidates in some sane way?
4529 for (UnresolvedSetIterator I = SpecBegin; I != SpecEnd; ++I) {
4530 PartialDiagnostic PD = CandidateDiag;
4531 PD << getTemplateArgumentBindingsText(
4532 cast<FunctionDecl>(*I)->getPrimaryTemplate()->getTemplateParameters(),
4533 *cast<FunctionDecl>(*I)->getTemplateSpecializationArgs());
4534 if (!TargetType.isNull())
4535 HandleFunctionTypeMismatch(PD, cast<FunctionDecl>(*I)->getType(),
4537 Diag((*I)->getLocation(), PD);
4544 /// \brief Returns the more specialized class template partial specialization
4545 /// according to the rules of partial ordering of class template partial
4546 /// specializations (C++ [temp.class.order]).
4548 /// \param PS1 the first class template partial specialization
4550 /// \param PS2 the second class template partial specialization
4552 /// \returns the more specialized class template partial specialization. If
4553 /// neither partial specialization is more specialized, returns NULL.
4554 ClassTemplatePartialSpecializationDecl *
4555 Sema::getMoreSpecializedPartialSpecialization(
4556 ClassTemplatePartialSpecializationDecl *PS1,
4557 ClassTemplatePartialSpecializationDecl *PS2,
4558 SourceLocation Loc) {
4559 // C++ [temp.class.order]p1:
4560 // For two class template partial specializations, the first is at least as
4561 // specialized as the second if, given the following rewrite to two
4562 // function templates, the first function template is at least as
4563 // specialized as the second according to the ordering rules for function
4564 // templates (14.6.6.2):
4565 // - the first function template has the same template parameters as the
4566 // first partial specialization and has a single function parameter
4567 // whose type is a class template specialization with the template
4568 // arguments of the first partial specialization, and
4569 // - the second function template has the same template parameters as the
4570 // second partial specialization and has a single function parameter
4571 // whose type is a class template specialization with the template
4572 // arguments of the second partial specialization.
4574 // Rather than synthesize function templates, we merely perform the
4575 // equivalent partial ordering by performing deduction directly on
4576 // the template arguments of the class template partial
4577 // specializations. This computation is slightly simpler than the
4578 // general problem of function template partial ordering, because
4579 // class template partial specializations are more constrained. We
4580 // know that every template parameter is deducible from the class
4581 // template partial specialization's template arguments, for
4583 SmallVector<DeducedTemplateArgument, 4> Deduced;
4584 TemplateDeductionInfo Info(Loc);
4586 QualType PT1 = PS1->getInjectedSpecializationType();
4587 QualType PT2 = PS2->getInjectedSpecializationType();
4589 // Determine whether PS1 is at least as specialized as PS2
4590 Deduced.resize(PS2->getTemplateParameters()->size());
4591 bool Better1 = !DeduceTemplateArgumentsByTypeMatch(*this,
4592 PS2->getTemplateParameters(),
4593 PT2, PT1, Info, Deduced, TDF_None,
4594 /*PartialOrdering=*/true,
4595 /*RefParamComparisons=*/nullptr);
4597 SmallVector<TemplateArgument, 4> DeducedArgs(Deduced.begin(),Deduced.end());
4598 InstantiatingTemplate Inst(*this, Loc, PS2, DeducedArgs, Info);
4599 Better1 = !::FinishTemplateArgumentDeduction(
4600 *this, PS2, PS1->getTemplateArgs(), Deduced, Info);
4603 // Determine whether PS2 is at least as specialized as PS1
4605 Deduced.resize(PS1->getTemplateParameters()->size());
4606 bool Better2 = !DeduceTemplateArgumentsByTypeMatch(
4607 *this, PS1->getTemplateParameters(), PT1, PT2, Info, Deduced, TDF_None,
4608 /*PartialOrdering=*/true,
4609 /*RefParamComparisons=*/nullptr);
4611 SmallVector<TemplateArgument, 4> DeducedArgs(Deduced.begin(),
4613 InstantiatingTemplate Inst(*this, Loc, PS1, DeducedArgs, Info);
4614 Better2 = !::FinishTemplateArgumentDeduction(
4615 *this, PS1, PS2->getTemplateArgs(), Deduced, Info);
4618 if (Better1 == Better2)
4621 return Better1 ? PS1 : PS2;
4624 /// TODO: Unify with ClassTemplatePartialSpecializationDecl version?
4625 /// May require unifying ClassTemplate(Partial)SpecializationDecl and
4626 /// VarTemplate(Partial)SpecializationDecl with a new data
4627 /// structure Template(Partial)SpecializationDecl, and
4628 /// using Template(Partial)SpecializationDecl as input type.
4629 VarTemplatePartialSpecializationDecl *
4630 Sema::getMoreSpecializedPartialSpecialization(
4631 VarTemplatePartialSpecializationDecl *PS1,
4632 VarTemplatePartialSpecializationDecl *PS2, SourceLocation Loc) {
4633 SmallVector<DeducedTemplateArgument, 4> Deduced;
4634 TemplateDeductionInfo Info(Loc);
4636 assert(PS1->getSpecializedTemplate() == PS2->getSpecializedTemplate() &&
4637 "the partial specializations being compared should specialize"
4638 " the same template.");
4639 TemplateName Name(PS1->getSpecializedTemplate());
4640 TemplateName CanonTemplate = Context.getCanonicalTemplateName(Name);
4641 QualType PT1 = Context.getTemplateSpecializationType(
4642 CanonTemplate, PS1->getTemplateArgs().data(),
4643 PS1->getTemplateArgs().size());
4644 QualType PT2 = Context.getTemplateSpecializationType(
4645 CanonTemplate, PS2->getTemplateArgs().data(),
4646 PS2->getTemplateArgs().size());
4648 // Determine whether PS1 is at least as specialized as PS2
4649 Deduced.resize(PS2->getTemplateParameters()->size());
4650 bool Better1 = !DeduceTemplateArgumentsByTypeMatch(
4651 *this, PS2->getTemplateParameters(), PT2, PT1, Info, Deduced, TDF_None,
4652 /*PartialOrdering=*/true,
4653 /*RefParamComparisons=*/nullptr);
4655 SmallVector<TemplateArgument, 4> DeducedArgs(Deduced.begin(),
4657 InstantiatingTemplate Inst(*this, Loc, PS2, DeducedArgs, Info);
4658 Better1 = !::FinishTemplateArgumentDeduction(*this, PS2,
4659 PS1->getTemplateArgs(),
4663 // Determine whether PS2 is at least as specialized as PS1
4665 Deduced.resize(PS1->getTemplateParameters()->size());
4666 bool Better2 = !DeduceTemplateArgumentsByTypeMatch(*this,
4667 PS1->getTemplateParameters(),
4668 PT1, PT2, Info, Deduced, TDF_None,
4669 /*PartialOrdering=*/true,
4670 /*RefParamComparisons=*/nullptr);
4672 SmallVector<TemplateArgument, 4> DeducedArgs(Deduced.begin(),Deduced.end());
4673 InstantiatingTemplate Inst(*this, Loc, PS1, DeducedArgs, Info);
4674 Better2 = !::FinishTemplateArgumentDeduction(*this, PS1,
4675 PS2->getTemplateArgs(),
4679 if (Better1 == Better2)
4682 return Better1? PS1 : PS2;
4686 MarkUsedTemplateParameters(ASTContext &Ctx,
4687 const TemplateArgument &TemplateArg,
4690 llvm::SmallBitVector &Used);
4692 /// \brief Mark the template parameters that are used by the given
4695 MarkUsedTemplateParameters(ASTContext &Ctx,
4699 llvm::SmallBitVector &Used) {
4700 // We can deduce from a pack expansion.
4701 if (const PackExpansionExpr *Expansion = dyn_cast<PackExpansionExpr>(E))
4702 E = Expansion->getPattern();
4704 // Skip through any implicit casts we added while type-checking, and any
4705 // substitutions performed by template alias expansion.
4707 if (const ImplicitCastExpr *ICE = dyn_cast<ImplicitCastExpr>(E))
4708 E = ICE->getSubExpr();
4709 else if (const SubstNonTypeTemplateParmExpr *Subst =
4710 dyn_cast<SubstNonTypeTemplateParmExpr>(E))
4711 E = Subst->getReplacement();
4716 // FIXME: if !OnlyDeduced, we have to walk the whole subexpression to
4717 // find other occurrences of template parameters.
4718 const DeclRefExpr *DRE = dyn_cast<DeclRefExpr>(E);
4722 const NonTypeTemplateParmDecl *NTTP
4723 = dyn_cast<NonTypeTemplateParmDecl>(DRE->getDecl());
4727 if (NTTP->getDepth() == Depth)
4728 Used[NTTP->getIndex()] = true;
4731 /// \brief Mark the template parameters that are used by the given
4732 /// nested name specifier.
4734 MarkUsedTemplateParameters(ASTContext &Ctx,
4735 NestedNameSpecifier *NNS,
4738 llvm::SmallBitVector &Used) {
4742 MarkUsedTemplateParameters(Ctx, NNS->getPrefix(), OnlyDeduced, Depth,
4744 MarkUsedTemplateParameters(Ctx, QualType(NNS->getAsType(), 0),
4745 OnlyDeduced, Depth, Used);
4748 /// \brief Mark the template parameters that are used by the given
4751 MarkUsedTemplateParameters(ASTContext &Ctx,
4755 llvm::SmallBitVector &Used) {
4756 if (TemplateDecl *Template = Name.getAsTemplateDecl()) {
4757 if (TemplateTemplateParmDecl *TTP
4758 = dyn_cast<TemplateTemplateParmDecl>(Template)) {
4759 if (TTP->getDepth() == Depth)
4760 Used[TTP->getIndex()] = true;
4765 if (QualifiedTemplateName *QTN = Name.getAsQualifiedTemplateName())
4766 MarkUsedTemplateParameters(Ctx, QTN->getQualifier(), OnlyDeduced,
4768 if (DependentTemplateName *DTN = Name.getAsDependentTemplateName())
4769 MarkUsedTemplateParameters(Ctx, DTN->getQualifier(), OnlyDeduced,
4773 /// \brief Mark the template parameters that are used by the given
4776 MarkUsedTemplateParameters(ASTContext &Ctx, QualType T,
4779 llvm::SmallBitVector &Used) {
4783 // Non-dependent types have nothing deducible
4784 if (!T->isDependentType())
4787 T = Ctx.getCanonicalType(T);
4788 switch (T->getTypeClass()) {
4790 MarkUsedTemplateParameters(Ctx,
4791 cast<PointerType>(T)->getPointeeType(),
4797 case Type::BlockPointer:
4798 MarkUsedTemplateParameters(Ctx,
4799 cast<BlockPointerType>(T)->getPointeeType(),
4805 case Type::LValueReference:
4806 case Type::RValueReference:
4807 MarkUsedTemplateParameters(Ctx,
4808 cast<ReferenceType>(T)->getPointeeType(),
4814 case Type::MemberPointer: {
4815 const MemberPointerType *MemPtr = cast<MemberPointerType>(T.getTypePtr());
4816 MarkUsedTemplateParameters(Ctx, MemPtr->getPointeeType(), OnlyDeduced,
4818 MarkUsedTemplateParameters(Ctx, QualType(MemPtr->getClass(), 0),
4819 OnlyDeduced, Depth, Used);
4823 case Type::DependentSizedArray:
4824 MarkUsedTemplateParameters(Ctx,
4825 cast<DependentSizedArrayType>(T)->getSizeExpr(),
4826 OnlyDeduced, Depth, Used);
4827 // Fall through to check the element type
4829 case Type::ConstantArray:
4830 case Type::IncompleteArray:
4831 MarkUsedTemplateParameters(Ctx,
4832 cast<ArrayType>(T)->getElementType(),
4833 OnlyDeduced, Depth, Used);
4837 case Type::ExtVector:
4838 MarkUsedTemplateParameters(Ctx,
4839 cast<VectorType>(T)->getElementType(),
4840 OnlyDeduced, Depth, Used);
4843 case Type::DependentSizedExtVector: {
4844 const DependentSizedExtVectorType *VecType
4845 = cast<DependentSizedExtVectorType>(T);
4846 MarkUsedTemplateParameters(Ctx, VecType->getElementType(), OnlyDeduced,
4848 MarkUsedTemplateParameters(Ctx, VecType->getSizeExpr(), OnlyDeduced,
4853 case Type::FunctionProto: {
4854 const FunctionProtoType *Proto = cast<FunctionProtoType>(T);
4855 MarkUsedTemplateParameters(Ctx, Proto->getReturnType(), OnlyDeduced, Depth,
4857 for (unsigned I = 0, N = Proto->getNumParams(); I != N; ++I)
4858 MarkUsedTemplateParameters(Ctx, Proto->getParamType(I), OnlyDeduced,
4863 case Type::TemplateTypeParm: {
4864 const TemplateTypeParmType *TTP = cast<TemplateTypeParmType>(T);
4865 if (TTP->getDepth() == Depth)
4866 Used[TTP->getIndex()] = true;
4870 case Type::SubstTemplateTypeParmPack: {
4871 const SubstTemplateTypeParmPackType *Subst
4872 = cast<SubstTemplateTypeParmPackType>(T);
4873 MarkUsedTemplateParameters(Ctx,
4874 QualType(Subst->getReplacedParameter(), 0),
4875 OnlyDeduced, Depth, Used);
4876 MarkUsedTemplateParameters(Ctx, Subst->getArgumentPack(),
4877 OnlyDeduced, Depth, Used);
4881 case Type::InjectedClassName:
4882 T = cast<InjectedClassNameType>(T)->getInjectedSpecializationType();
4885 case Type::TemplateSpecialization: {
4886 const TemplateSpecializationType *Spec
4887 = cast<TemplateSpecializationType>(T);
4888 MarkUsedTemplateParameters(Ctx, Spec->getTemplateName(), OnlyDeduced,
4891 // C++0x [temp.deduct.type]p9:
4892 // If the template argument list of P contains a pack expansion that is
4893 // not the last template argument, the entire template argument list is a
4894 // non-deduced context.
4896 hasPackExpansionBeforeEnd(Spec->getArgs(), Spec->getNumArgs()))
4899 for (unsigned I = 0, N = Spec->getNumArgs(); I != N; ++I)
4900 MarkUsedTemplateParameters(Ctx, Spec->getArg(I), OnlyDeduced, Depth,
4907 MarkUsedTemplateParameters(Ctx,
4908 cast<ComplexType>(T)->getElementType(),
4909 OnlyDeduced, Depth, Used);
4914 MarkUsedTemplateParameters(Ctx,
4915 cast<AtomicType>(T)->getValueType(),
4916 OnlyDeduced, Depth, Used);
4919 case Type::DependentName:
4921 MarkUsedTemplateParameters(Ctx,
4922 cast<DependentNameType>(T)->getQualifier(),
4923 OnlyDeduced, Depth, Used);
4926 case Type::DependentTemplateSpecialization: {
4927 const DependentTemplateSpecializationType *Spec
4928 = cast<DependentTemplateSpecializationType>(T);
4930 MarkUsedTemplateParameters(Ctx, Spec->getQualifier(),
4931 OnlyDeduced, Depth, Used);
4933 // C++0x [temp.deduct.type]p9:
4934 // If the template argument list of P contains a pack expansion that is not
4935 // the last template argument, the entire template argument list is a
4936 // non-deduced context.
4938 hasPackExpansionBeforeEnd(Spec->getArgs(), Spec->getNumArgs()))
4941 for (unsigned I = 0, N = Spec->getNumArgs(); I != N; ++I)
4942 MarkUsedTemplateParameters(Ctx, Spec->getArg(I), OnlyDeduced, Depth,
4949 MarkUsedTemplateParameters(Ctx,
4950 cast<TypeOfType>(T)->getUnderlyingType(),
4951 OnlyDeduced, Depth, Used);
4954 case Type::TypeOfExpr:
4956 MarkUsedTemplateParameters(Ctx,
4957 cast<TypeOfExprType>(T)->getUnderlyingExpr(),
4958 OnlyDeduced, Depth, Used);
4961 case Type::Decltype:
4963 MarkUsedTemplateParameters(Ctx,
4964 cast<DecltypeType>(T)->getUnderlyingExpr(),
4965 OnlyDeduced, Depth, Used);
4968 case Type::UnaryTransform:
4970 MarkUsedTemplateParameters(Ctx,
4971 cast<UnaryTransformType>(T)->getUnderlyingType(),
4972 OnlyDeduced, Depth, Used);
4975 case Type::PackExpansion:
4976 MarkUsedTemplateParameters(Ctx,
4977 cast<PackExpansionType>(T)->getPattern(),
4978 OnlyDeduced, Depth, Used);
4982 MarkUsedTemplateParameters(Ctx,
4983 cast<AutoType>(T)->getDeducedType(),
4984 OnlyDeduced, Depth, Used);
4986 // None of these types have any template parameters in them.
4988 case Type::VariableArray:
4989 case Type::FunctionNoProto:
4992 case Type::ObjCInterface:
4993 case Type::ObjCObject:
4994 case Type::ObjCObjectPointer:
4995 case Type::UnresolvedUsing:
4996 #define TYPE(Class, Base)
4997 #define ABSTRACT_TYPE(Class, Base)
4998 #define DEPENDENT_TYPE(Class, Base)
4999 #define NON_CANONICAL_TYPE(Class, Base) case Type::Class:
5000 #include "clang/AST/TypeNodes.def"
5005 /// \brief Mark the template parameters that are used by this
5006 /// template argument.
5008 MarkUsedTemplateParameters(ASTContext &Ctx,
5009 const TemplateArgument &TemplateArg,
5012 llvm::SmallBitVector &Used) {
5013 switch (TemplateArg.getKind()) {
5014 case TemplateArgument::Null:
5015 case TemplateArgument::Integral:
5016 case TemplateArgument::Declaration:
5019 case TemplateArgument::NullPtr:
5020 MarkUsedTemplateParameters(Ctx, TemplateArg.getNullPtrType(), OnlyDeduced,
5024 case TemplateArgument::Type:
5025 MarkUsedTemplateParameters(Ctx, TemplateArg.getAsType(), OnlyDeduced,
5029 case TemplateArgument::Template:
5030 case TemplateArgument::TemplateExpansion:
5031 MarkUsedTemplateParameters(Ctx,
5032 TemplateArg.getAsTemplateOrTemplatePattern(),
5033 OnlyDeduced, Depth, Used);
5036 case TemplateArgument::Expression:
5037 MarkUsedTemplateParameters(Ctx, TemplateArg.getAsExpr(), OnlyDeduced,
5041 case TemplateArgument::Pack:
5042 for (const auto &P : TemplateArg.pack_elements())
5043 MarkUsedTemplateParameters(Ctx, P, OnlyDeduced, Depth, Used);
5048 /// \brief Mark which template parameters can be deduced from a given
5049 /// template argument list.
5051 /// \param TemplateArgs the template argument list from which template
5052 /// parameters will be deduced.
5054 /// \param Used a bit vector whose elements will be set to \c true
5055 /// to indicate when the corresponding template parameter will be
5058 Sema::MarkUsedTemplateParameters(const TemplateArgumentList &TemplateArgs,
5059 bool OnlyDeduced, unsigned Depth,
5060 llvm::SmallBitVector &Used) {
5061 // C++0x [temp.deduct.type]p9:
5062 // If the template argument list of P contains a pack expansion that is not
5063 // the last template argument, the entire template argument list is a
5064 // non-deduced context.
5066 hasPackExpansionBeforeEnd(TemplateArgs.data(), TemplateArgs.size()))
5069 for (unsigned I = 0, N = TemplateArgs.size(); I != N; ++I)
5070 ::MarkUsedTemplateParameters(Context, TemplateArgs[I], OnlyDeduced,
5074 /// \brief Marks all of the template parameters that will be deduced by a
5075 /// call to the given function template.
5076 void Sema::MarkDeducedTemplateParameters(
5077 ASTContext &Ctx, const FunctionTemplateDecl *FunctionTemplate,
5078 llvm::SmallBitVector &Deduced) {
5079 TemplateParameterList *TemplateParams
5080 = FunctionTemplate->getTemplateParameters();
5082 Deduced.resize(TemplateParams->size());
5084 FunctionDecl *Function = FunctionTemplate->getTemplatedDecl();
5085 for (unsigned I = 0, N = Function->getNumParams(); I != N; ++I)
5086 ::MarkUsedTemplateParameters(Ctx, Function->getParamDecl(I)->getType(),
5087 true, TemplateParams->getDepth(), Deduced);
5090 bool hasDeducibleTemplateParameters(Sema &S,
5091 FunctionTemplateDecl *FunctionTemplate,
5093 if (!T->isDependentType())
5096 TemplateParameterList *TemplateParams
5097 = FunctionTemplate->getTemplateParameters();
5098 llvm::SmallBitVector Deduced(TemplateParams->size());
5099 ::MarkUsedTemplateParameters(S.Context, T, true, TemplateParams->getDepth(),
5102 return Deduced.any();