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 static Sema::TemplateDeductionResult
95 DeduceTemplateArgumentsByTypeMatch(Sema &S,
96 TemplateParameterList *TemplateParams,
99 TemplateDeductionInfo &Info,
100 SmallVectorImpl<DeducedTemplateArgument> &
103 bool PartialOrdering = false);
105 static Sema::TemplateDeductionResult
106 DeduceTemplateArguments(Sema &S,
107 TemplateParameterList *TemplateParams,
108 const TemplateArgument *Params, unsigned NumParams,
109 const TemplateArgument *Args, unsigned NumArgs,
110 TemplateDeductionInfo &Info,
111 SmallVectorImpl<DeducedTemplateArgument> &Deduced);
113 /// \brief If the given expression is of a form that permits the deduction
114 /// of a non-type template parameter, return the declaration of that
115 /// non-type template parameter.
116 static NonTypeTemplateParmDecl *getDeducedParameterFromExpr(Expr *E) {
117 // If we are within an alias template, the expression may have undergone
118 // any number of parameter substitutions already.
120 if (ImplicitCastExpr *IC = dyn_cast<ImplicitCastExpr>(E))
121 E = IC->getSubExpr();
122 else if (SubstNonTypeTemplateParmExpr *Subst =
123 dyn_cast<SubstNonTypeTemplateParmExpr>(E))
124 E = Subst->getReplacement();
129 if (DeclRefExpr *DRE = dyn_cast<DeclRefExpr>(E))
130 return dyn_cast<NonTypeTemplateParmDecl>(DRE->getDecl());
135 /// \brief Determine whether two declaration pointers refer to the same
137 static bool isSameDeclaration(Decl *X, Decl *Y) {
138 if (NamedDecl *NX = dyn_cast<NamedDecl>(X))
139 X = NX->getUnderlyingDecl();
140 if (NamedDecl *NY = dyn_cast<NamedDecl>(Y))
141 Y = NY->getUnderlyingDecl();
143 return X->getCanonicalDecl() == Y->getCanonicalDecl();
146 /// \brief Verify that the given, deduced template arguments are compatible.
148 /// \returns The deduced template argument, or a NULL template argument if
149 /// the deduced template arguments were incompatible.
150 static DeducedTemplateArgument
151 checkDeducedTemplateArguments(ASTContext &Context,
152 const DeducedTemplateArgument &X,
153 const DeducedTemplateArgument &Y) {
154 // We have no deduction for one or both of the arguments; they're compatible.
160 switch (X.getKind()) {
161 case TemplateArgument::Null:
162 llvm_unreachable("Non-deduced template arguments handled above");
164 case TemplateArgument::Type:
165 // If two template type arguments have the same type, they're compatible.
166 if (Y.getKind() == TemplateArgument::Type &&
167 Context.hasSameType(X.getAsType(), Y.getAsType()))
170 return DeducedTemplateArgument();
172 case TemplateArgument::Integral:
173 // If we deduced a constant in one case and either a dependent expression or
174 // declaration in another case, keep the integral constant.
175 // If both are integral constants with the same value, keep that value.
176 if (Y.getKind() == TemplateArgument::Expression ||
177 Y.getKind() == TemplateArgument::Declaration ||
178 (Y.getKind() == TemplateArgument::Integral &&
179 hasSameExtendedValue(X.getAsIntegral(), Y.getAsIntegral())))
180 return DeducedTemplateArgument(X,
181 X.wasDeducedFromArrayBound() &&
182 Y.wasDeducedFromArrayBound());
184 // All other combinations are incompatible.
185 return DeducedTemplateArgument();
187 case TemplateArgument::Template:
188 if (Y.getKind() == TemplateArgument::Template &&
189 Context.hasSameTemplateName(X.getAsTemplate(), Y.getAsTemplate()))
192 // All other combinations are incompatible.
193 return DeducedTemplateArgument();
195 case TemplateArgument::TemplateExpansion:
196 if (Y.getKind() == TemplateArgument::TemplateExpansion &&
197 Context.hasSameTemplateName(X.getAsTemplateOrTemplatePattern(),
198 Y.getAsTemplateOrTemplatePattern()))
201 // All other combinations are incompatible.
202 return DeducedTemplateArgument();
204 case TemplateArgument::Expression:
205 // If we deduced a dependent expression in one case and either an integral
206 // constant or a declaration in another case, keep the integral constant
208 if (Y.getKind() == TemplateArgument::Integral ||
209 Y.getKind() == TemplateArgument::Declaration)
210 return DeducedTemplateArgument(Y, X.wasDeducedFromArrayBound() &&
211 Y.wasDeducedFromArrayBound());
213 if (Y.getKind() == TemplateArgument::Expression) {
214 // Compare the expressions for equality
215 llvm::FoldingSetNodeID ID1, ID2;
216 X.getAsExpr()->Profile(ID1, Context, true);
217 Y.getAsExpr()->Profile(ID2, Context, true);
222 // All other combinations are incompatible.
223 return DeducedTemplateArgument();
225 case TemplateArgument::Declaration:
226 // If we deduced a declaration and a dependent expression, keep the
228 if (Y.getKind() == TemplateArgument::Expression)
231 // If we deduced a declaration and an integral constant, keep the
232 // integral constant.
233 if (Y.getKind() == TemplateArgument::Integral)
236 // If we deduced two declarations, make sure they they refer to the
238 if (Y.getKind() == TemplateArgument::Declaration &&
239 isSameDeclaration(X.getAsDecl(), Y.getAsDecl()))
242 // All other combinations are incompatible.
243 return DeducedTemplateArgument();
245 case TemplateArgument::NullPtr:
246 // If we deduced a null pointer and a dependent expression, keep the
248 if (Y.getKind() == TemplateArgument::Expression)
251 // If we deduced a null pointer and an integral constant, keep the
252 // integral constant.
253 if (Y.getKind() == TemplateArgument::Integral)
256 // If we deduced two null pointers, make sure they have the same type.
257 if (Y.getKind() == TemplateArgument::NullPtr &&
258 Context.hasSameType(X.getNullPtrType(), Y.getNullPtrType()))
261 // All other combinations are incompatible.
262 return DeducedTemplateArgument();
264 case TemplateArgument::Pack:
265 if (Y.getKind() != TemplateArgument::Pack ||
266 X.pack_size() != Y.pack_size())
267 return DeducedTemplateArgument();
269 for (TemplateArgument::pack_iterator XA = X.pack_begin(),
270 XAEnd = X.pack_end(),
272 XA != XAEnd; ++XA, ++YA) {
273 // FIXME: Do we need to merge the results together here?
274 if (checkDeducedTemplateArguments(Context,
275 DeducedTemplateArgument(*XA, X.wasDeducedFromArrayBound()),
276 DeducedTemplateArgument(*YA, Y.wasDeducedFromArrayBound()))
278 return DeducedTemplateArgument();
284 llvm_unreachable("Invalid TemplateArgument Kind!");
287 /// \brief Deduce the value of the given non-type template parameter
288 /// from the given constant.
289 static Sema::TemplateDeductionResult
290 DeduceNonTypeTemplateArgument(Sema &S,
291 NonTypeTemplateParmDecl *NTTP,
292 llvm::APSInt Value, QualType ValueType,
293 bool DeducedFromArrayBound,
294 TemplateDeductionInfo &Info,
295 SmallVectorImpl<DeducedTemplateArgument> &Deduced) {
296 assert(NTTP->getDepth() == 0 &&
297 "Cannot deduce non-type template argument with depth > 0");
299 DeducedTemplateArgument NewDeduced(S.Context, Value, ValueType,
300 DeducedFromArrayBound);
301 DeducedTemplateArgument Result = checkDeducedTemplateArguments(S.Context,
302 Deduced[NTTP->getIndex()],
304 if (Result.isNull()) {
306 Info.FirstArg = Deduced[NTTP->getIndex()];
307 Info.SecondArg = NewDeduced;
308 return Sema::TDK_Inconsistent;
311 Deduced[NTTP->getIndex()] = Result;
312 return Sema::TDK_Success;
315 /// \brief Deduce the value of the given non-type template parameter
316 /// from the given type- or value-dependent expression.
318 /// \returns true if deduction succeeded, false otherwise.
319 static Sema::TemplateDeductionResult
320 DeduceNonTypeTemplateArgument(Sema &S,
321 NonTypeTemplateParmDecl *NTTP,
323 TemplateDeductionInfo &Info,
324 SmallVectorImpl<DeducedTemplateArgument> &Deduced) {
325 assert(NTTP->getDepth() == 0 &&
326 "Cannot deduce non-type template argument with depth > 0");
327 assert((Value->isTypeDependent() || Value->isValueDependent()) &&
328 "Expression template argument must be type- or value-dependent.");
330 DeducedTemplateArgument NewDeduced(Value);
331 DeducedTemplateArgument Result = checkDeducedTemplateArguments(S.Context,
332 Deduced[NTTP->getIndex()],
335 if (Result.isNull()) {
337 Info.FirstArg = Deduced[NTTP->getIndex()];
338 Info.SecondArg = NewDeduced;
339 return Sema::TDK_Inconsistent;
342 Deduced[NTTP->getIndex()] = Result;
343 return Sema::TDK_Success;
346 /// \brief Deduce the value of the given non-type template parameter
347 /// from the given declaration.
349 /// \returns true if deduction succeeded, false otherwise.
350 static Sema::TemplateDeductionResult
351 DeduceNonTypeTemplateArgument(Sema &S,
352 NonTypeTemplateParmDecl *NTTP,
354 TemplateDeductionInfo &Info,
355 SmallVectorImpl<DeducedTemplateArgument> &Deduced) {
356 assert(NTTP->getDepth() == 0 &&
357 "Cannot deduce non-type template argument with depth > 0");
359 D = D ? cast<ValueDecl>(D->getCanonicalDecl()) : nullptr;
360 TemplateArgument New(D, NTTP->getType());
361 DeducedTemplateArgument NewDeduced(New);
362 DeducedTemplateArgument Result = checkDeducedTemplateArguments(S.Context,
363 Deduced[NTTP->getIndex()],
365 if (Result.isNull()) {
367 Info.FirstArg = Deduced[NTTP->getIndex()];
368 Info.SecondArg = NewDeduced;
369 return Sema::TDK_Inconsistent;
372 Deduced[NTTP->getIndex()] = Result;
373 return Sema::TDK_Success;
376 static Sema::TemplateDeductionResult
377 DeduceTemplateArguments(Sema &S,
378 TemplateParameterList *TemplateParams,
381 TemplateDeductionInfo &Info,
382 SmallVectorImpl<DeducedTemplateArgument> &Deduced) {
383 TemplateDecl *ParamDecl = Param.getAsTemplateDecl();
385 // The parameter type is dependent and is not a template template parameter,
386 // so there is nothing that we can deduce.
387 return Sema::TDK_Success;
390 if (TemplateTemplateParmDecl *TempParam
391 = dyn_cast<TemplateTemplateParmDecl>(ParamDecl)) {
392 DeducedTemplateArgument NewDeduced(S.Context.getCanonicalTemplateName(Arg));
393 DeducedTemplateArgument Result = checkDeducedTemplateArguments(S.Context,
394 Deduced[TempParam->getIndex()],
396 if (Result.isNull()) {
397 Info.Param = TempParam;
398 Info.FirstArg = Deduced[TempParam->getIndex()];
399 Info.SecondArg = NewDeduced;
400 return Sema::TDK_Inconsistent;
403 Deduced[TempParam->getIndex()] = Result;
404 return Sema::TDK_Success;
407 // Verify that the two template names are equivalent.
408 if (S.Context.hasSameTemplateName(Param, Arg))
409 return Sema::TDK_Success;
411 // Mismatch of non-dependent template parameter to argument.
412 Info.FirstArg = TemplateArgument(Param);
413 Info.SecondArg = TemplateArgument(Arg);
414 return Sema::TDK_NonDeducedMismatch;
417 /// \brief Deduce the template arguments by comparing the template parameter
418 /// type (which is a template-id) with the template argument type.
420 /// \param S the Sema
422 /// \param TemplateParams the template parameters that we are deducing
424 /// \param Param the parameter type
426 /// \param Arg the argument type
428 /// \param Info information about the template argument deduction itself
430 /// \param Deduced the deduced template arguments
432 /// \returns the result of template argument deduction so far. Note that a
433 /// "success" result means that template argument deduction has not yet failed,
434 /// but it may still fail, later, for other reasons.
435 static Sema::TemplateDeductionResult
436 DeduceTemplateArguments(Sema &S,
437 TemplateParameterList *TemplateParams,
438 const TemplateSpecializationType *Param,
440 TemplateDeductionInfo &Info,
441 SmallVectorImpl<DeducedTemplateArgument> &Deduced) {
442 assert(Arg.isCanonical() && "Argument type must be canonical");
444 // Check whether the template argument is a dependent template-id.
445 if (const TemplateSpecializationType *SpecArg
446 = dyn_cast<TemplateSpecializationType>(Arg)) {
447 // Perform template argument deduction for the template name.
448 if (Sema::TemplateDeductionResult Result
449 = DeduceTemplateArguments(S, TemplateParams,
450 Param->getTemplateName(),
451 SpecArg->getTemplateName(),
456 // Perform template argument deduction on each template
457 // argument. Ignore any missing/extra arguments, since they could be
458 // filled in by default arguments.
459 return DeduceTemplateArguments(S, TemplateParams,
460 Param->getArgs(), Param->getNumArgs(),
461 SpecArg->getArgs(), SpecArg->getNumArgs(),
465 // If the argument type is a class template specialization, we
466 // perform template argument deduction using its template
468 const RecordType *RecordArg = dyn_cast<RecordType>(Arg);
470 Info.FirstArg = TemplateArgument(QualType(Param, 0));
471 Info.SecondArg = TemplateArgument(Arg);
472 return Sema::TDK_NonDeducedMismatch;
475 ClassTemplateSpecializationDecl *SpecArg
476 = dyn_cast<ClassTemplateSpecializationDecl>(RecordArg->getDecl());
478 Info.FirstArg = TemplateArgument(QualType(Param, 0));
479 Info.SecondArg = TemplateArgument(Arg);
480 return Sema::TDK_NonDeducedMismatch;
483 // Perform template argument deduction for the template name.
484 if (Sema::TemplateDeductionResult Result
485 = DeduceTemplateArguments(S,
487 Param->getTemplateName(),
488 TemplateName(SpecArg->getSpecializedTemplate()),
492 // Perform template argument deduction for the template arguments.
493 return DeduceTemplateArguments(S, TemplateParams,
494 Param->getArgs(), Param->getNumArgs(),
495 SpecArg->getTemplateArgs().data(),
496 SpecArg->getTemplateArgs().size(),
500 /// \brief Determines whether the given type is an opaque type that
501 /// might be more qualified when instantiated.
502 static bool IsPossiblyOpaquelyQualifiedType(QualType T) {
503 switch (T->getTypeClass()) {
504 case Type::TypeOfExpr:
506 case Type::DependentName:
508 case Type::UnresolvedUsing:
509 case Type::TemplateTypeParm:
512 case Type::ConstantArray:
513 case Type::IncompleteArray:
514 case Type::VariableArray:
515 case Type::DependentSizedArray:
516 return IsPossiblyOpaquelyQualifiedType(
517 cast<ArrayType>(T)->getElementType());
524 /// \brief Retrieve the depth and index of a template parameter.
525 static std::pair<unsigned, unsigned>
526 getDepthAndIndex(NamedDecl *ND) {
527 if (TemplateTypeParmDecl *TTP = dyn_cast<TemplateTypeParmDecl>(ND))
528 return std::make_pair(TTP->getDepth(), TTP->getIndex());
530 if (NonTypeTemplateParmDecl *NTTP = dyn_cast<NonTypeTemplateParmDecl>(ND))
531 return std::make_pair(NTTP->getDepth(), NTTP->getIndex());
533 TemplateTemplateParmDecl *TTP = cast<TemplateTemplateParmDecl>(ND);
534 return std::make_pair(TTP->getDepth(), TTP->getIndex());
537 /// \brief Retrieve the depth and index of an unexpanded parameter pack.
538 static std::pair<unsigned, unsigned>
539 getDepthAndIndex(UnexpandedParameterPack UPP) {
540 if (const TemplateTypeParmType *TTP
541 = UPP.first.dyn_cast<const TemplateTypeParmType *>())
542 return std::make_pair(TTP->getDepth(), TTP->getIndex());
544 return getDepthAndIndex(UPP.first.get<NamedDecl *>());
547 /// \brief Helper function to build a TemplateParameter when we don't
548 /// know its type statically.
549 static TemplateParameter makeTemplateParameter(Decl *D) {
550 if (TemplateTypeParmDecl *TTP = dyn_cast<TemplateTypeParmDecl>(D))
551 return TemplateParameter(TTP);
552 if (NonTypeTemplateParmDecl *NTTP = dyn_cast<NonTypeTemplateParmDecl>(D))
553 return TemplateParameter(NTTP);
555 return TemplateParameter(cast<TemplateTemplateParmDecl>(D));
558 /// A pack that we're currently deducing.
559 struct clang::DeducedPack {
560 DeducedPack(unsigned Index) : Index(Index), Outer(nullptr) {}
562 // The index of the pack.
565 // The old value of the pack before we started deducing it.
566 DeducedTemplateArgument Saved;
568 // A deferred value of this pack from an inner deduction, that couldn't be
569 // deduced because this deduction hadn't happened yet.
570 DeducedTemplateArgument DeferredDeduction;
572 // The new value of the pack.
573 SmallVector<DeducedTemplateArgument, 4> New;
575 // The outer deduction for this pack, if any.
580 /// A scope in which we're performing pack deduction.
581 class PackDeductionScope {
583 PackDeductionScope(Sema &S, TemplateParameterList *TemplateParams,
584 SmallVectorImpl<DeducedTemplateArgument> &Deduced,
585 TemplateDeductionInfo &Info, TemplateArgument Pattern)
586 : S(S), TemplateParams(TemplateParams), Deduced(Deduced), Info(Info) {
587 // Compute the set of template parameter indices that correspond to
588 // parameter packs expanded by the pack expansion.
590 llvm::SmallBitVector SawIndices(TemplateParams->size());
591 SmallVector<UnexpandedParameterPack, 2> Unexpanded;
592 S.collectUnexpandedParameterPacks(Pattern, Unexpanded);
593 for (unsigned I = 0, N = Unexpanded.size(); I != N; ++I) {
594 unsigned Depth, Index;
595 std::tie(Depth, Index) = getDepthAndIndex(Unexpanded[I]);
596 if (Depth == 0 && !SawIndices[Index]) {
597 SawIndices[Index] = true;
599 // Save the deduced template argument for the parameter pack expanded
600 // by this pack expansion, then clear out the deduction.
601 DeducedPack Pack(Index);
602 Pack.Saved = Deduced[Index];
603 Deduced[Index] = TemplateArgument();
605 Packs.push_back(Pack);
609 assert(!Packs.empty() && "Pack expansion without unexpanded packs?");
611 for (auto &Pack : Packs) {
612 if (Info.PendingDeducedPacks.size() > Pack.Index)
613 Pack.Outer = Info.PendingDeducedPacks[Pack.Index];
615 Info.PendingDeducedPacks.resize(Pack.Index + 1);
616 Info.PendingDeducedPacks[Pack.Index] = &Pack;
618 if (S.CurrentInstantiationScope) {
619 // If the template argument pack was explicitly specified, add that to
620 // the set of deduced arguments.
621 const TemplateArgument *ExplicitArgs;
622 unsigned NumExplicitArgs;
623 NamedDecl *PartiallySubstitutedPack =
624 S.CurrentInstantiationScope->getPartiallySubstitutedPack(
625 &ExplicitArgs, &NumExplicitArgs);
626 if (PartiallySubstitutedPack &&
627 getDepthAndIndex(PartiallySubstitutedPack).second == Pack.Index)
628 Pack.New.append(ExplicitArgs, ExplicitArgs + NumExplicitArgs);
633 ~PackDeductionScope() {
634 for (auto &Pack : Packs)
635 Info.PendingDeducedPacks[Pack.Index] = Pack.Outer;
638 /// Move to deducing the next element in each pack that is being deduced.
639 void nextPackElement() {
640 // Capture the deduced template arguments for each parameter pack expanded
641 // by this pack expansion, add them to the list of arguments we've deduced
642 // for that pack, then clear out the deduced argument.
643 for (auto &Pack : Packs) {
644 DeducedTemplateArgument &DeducedArg = Deduced[Pack.Index];
645 if (!DeducedArg.isNull()) {
646 Pack.New.push_back(DeducedArg);
647 DeducedArg = DeducedTemplateArgument();
652 /// \brief Finish template argument deduction for a set of argument packs,
653 /// producing the argument packs and checking for consistency with prior
655 Sema::TemplateDeductionResult finish(bool HasAnyArguments) {
656 // Build argument packs for each of the parameter packs expanded by this
658 for (auto &Pack : Packs) {
659 // Put back the old value for this pack.
660 Deduced[Pack.Index] = Pack.Saved;
662 // Build or find a new value for this pack.
663 DeducedTemplateArgument NewPack;
664 if (HasAnyArguments && Pack.New.empty()) {
665 if (Pack.DeferredDeduction.isNull()) {
666 // We were not able to deduce anything for this parameter pack
667 // (because it only appeared in non-deduced contexts), so just
668 // restore the saved argument pack.
672 NewPack = Pack.DeferredDeduction;
673 Pack.DeferredDeduction = TemplateArgument();
674 } else if (Pack.New.empty()) {
675 // If we deduced an empty argument pack, create it now.
676 NewPack = DeducedTemplateArgument(TemplateArgument::getEmptyPack());
678 TemplateArgument *ArgumentPack =
679 new (S.Context) TemplateArgument[Pack.New.size()];
680 std::copy(Pack.New.begin(), Pack.New.end(), ArgumentPack);
681 NewPack = DeducedTemplateArgument(
682 TemplateArgument(llvm::makeArrayRef(ArgumentPack, Pack.New.size())),
683 Pack.New[0].wasDeducedFromArrayBound());
686 // Pick where we're going to put the merged pack.
687 DeducedTemplateArgument *Loc;
689 if (Pack.Outer->DeferredDeduction.isNull()) {
690 // Defer checking this pack until we have a complete pack to compare
692 Pack.Outer->DeferredDeduction = NewPack;
695 Loc = &Pack.Outer->DeferredDeduction;
697 Loc = &Deduced[Pack.Index];
700 // Check the new pack matches any previous value.
701 DeducedTemplateArgument OldPack = *Loc;
702 DeducedTemplateArgument Result =
703 checkDeducedTemplateArguments(S.Context, OldPack, NewPack);
705 // If we deferred a deduction of this pack, check that one now too.
706 if (!Result.isNull() && !Pack.DeferredDeduction.isNull()) {
708 NewPack = Pack.DeferredDeduction;
709 Result = checkDeducedTemplateArguments(S.Context, OldPack, NewPack);
712 if (Result.isNull()) {
714 makeTemplateParameter(TemplateParams->getParam(Pack.Index));
715 Info.FirstArg = OldPack;
716 Info.SecondArg = NewPack;
717 return Sema::TDK_Inconsistent;
723 return Sema::TDK_Success;
728 TemplateParameterList *TemplateParams;
729 SmallVectorImpl<DeducedTemplateArgument> &Deduced;
730 TemplateDeductionInfo &Info;
732 SmallVector<DeducedPack, 2> Packs;
736 /// \brief Deduce the template arguments by comparing the list of parameter
737 /// types to the list of argument types, as in the parameter-type-lists of
738 /// function types (C++ [temp.deduct.type]p10).
740 /// \param S The semantic analysis object within which we are deducing
742 /// \param TemplateParams The template parameters that we are deducing
744 /// \param Params The list of parameter types
746 /// \param NumParams The number of types in \c Params
748 /// \param Args The list of argument types
750 /// \param NumArgs The number of types in \c Args
752 /// \param Info information about the template argument deduction itself
754 /// \param Deduced the deduced template arguments
756 /// \param TDF bitwise OR of the TemplateDeductionFlags bits that describe
757 /// how template argument deduction is performed.
759 /// \param PartialOrdering If true, we are performing template argument
760 /// deduction for during partial ordering for a call
761 /// (C++0x [temp.deduct.partial]).
763 /// \returns the result of template argument deduction so far. Note that a
764 /// "success" result means that template argument deduction has not yet failed,
765 /// but it may still fail, later, for other reasons.
766 static Sema::TemplateDeductionResult
767 DeduceTemplateArguments(Sema &S,
768 TemplateParameterList *TemplateParams,
769 const QualType *Params, unsigned NumParams,
770 const QualType *Args, unsigned NumArgs,
771 TemplateDeductionInfo &Info,
772 SmallVectorImpl<DeducedTemplateArgument> &Deduced,
774 bool PartialOrdering = false) {
775 // Fast-path check to see if we have too many/too few arguments.
776 if (NumParams != NumArgs &&
777 !(NumParams && isa<PackExpansionType>(Params[NumParams - 1])) &&
778 !(NumArgs && isa<PackExpansionType>(Args[NumArgs - 1])))
779 return Sema::TDK_MiscellaneousDeductionFailure;
781 // C++0x [temp.deduct.type]p10:
782 // Similarly, if P has a form that contains (T), then each parameter type
783 // Pi of the respective parameter-type- list of P is compared with the
784 // corresponding parameter type Ai of the corresponding parameter-type-list
786 unsigned ArgIdx = 0, ParamIdx = 0;
787 for (; ParamIdx != NumParams; ++ParamIdx) {
788 // Check argument types.
789 const PackExpansionType *Expansion
790 = dyn_cast<PackExpansionType>(Params[ParamIdx]);
792 // Simple case: compare the parameter and argument types at this point.
794 // Make sure we have an argument.
795 if (ArgIdx >= NumArgs)
796 return Sema::TDK_MiscellaneousDeductionFailure;
798 if (isa<PackExpansionType>(Args[ArgIdx])) {
799 // C++0x [temp.deduct.type]p22:
800 // If the original function parameter associated with A is a function
801 // parameter pack and the function parameter associated with P is not
802 // a function parameter pack, then template argument deduction fails.
803 return Sema::TDK_MiscellaneousDeductionFailure;
806 if (Sema::TemplateDeductionResult Result
807 = DeduceTemplateArgumentsByTypeMatch(S, TemplateParams,
808 Params[ParamIdx], Args[ArgIdx],
817 // C++0x [temp.deduct.type]p5:
818 // The non-deduced contexts are:
819 // - A function parameter pack that does not occur at the end of the
820 // parameter-declaration-clause.
821 if (ParamIdx + 1 < NumParams)
822 return Sema::TDK_Success;
824 // C++0x [temp.deduct.type]p10:
825 // If the parameter-declaration corresponding to Pi is a function
826 // parameter pack, then the type of its declarator- id is compared with
827 // each remaining parameter type in the parameter-type-list of A. Each
828 // comparison deduces template arguments for subsequent positions in the
829 // template parameter packs expanded by the function parameter pack.
831 QualType Pattern = Expansion->getPattern();
832 PackDeductionScope PackScope(S, TemplateParams, Deduced, Info, Pattern);
834 bool HasAnyArguments = false;
835 for (; ArgIdx < NumArgs; ++ArgIdx) {
836 HasAnyArguments = true;
838 // Deduce template arguments from the pattern.
839 if (Sema::TemplateDeductionResult Result
840 = DeduceTemplateArgumentsByTypeMatch(S, TemplateParams, Pattern,
841 Args[ArgIdx], Info, Deduced,
842 TDF, PartialOrdering))
845 PackScope.nextPackElement();
848 // Build argument packs for each of the parameter packs expanded by this
850 if (auto Result = PackScope.finish(HasAnyArguments))
854 // Make sure we don't have any extra arguments.
855 if (ArgIdx < NumArgs)
856 return Sema::TDK_MiscellaneousDeductionFailure;
858 return Sema::TDK_Success;
861 /// \brief Determine whether the parameter has qualifiers that are either
862 /// inconsistent with or a superset of the argument's qualifiers.
863 static bool hasInconsistentOrSupersetQualifiersOf(QualType ParamType,
865 Qualifiers ParamQs = ParamType.getQualifiers();
866 Qualifiers ArgQs = ArgType.getQualifiers();
868 if (ParamQs == ArgQs)
871 // Mismatched (but not missing) Objective-C GC attributes.
872 if (ParamQs.getObjCGCAttr() != ArgQs.getObjCGCAttr() &&
873 ParamQs.hasObjCGCAttr())
876 // Mismatched (but not missing) address spaces.
877 if (ParamQs.getAddressSpace() != ArgQs.getAddressSpace() &&
878 ParamQs.hasAddressSpace())
881 // Mismatched (but not missing) Objective-C lifetime qualifiers.
882 if (ParamQs.getObjCLifetime() != ArgQs.getObjCLifetime() &&
883 ParamQs.hasObjCLifetime())
886 // CVR qualifier superset.
887 return (ParamQs.getCVRQualifiers() != ArgQs.getCVRQualifiers()) &&
888 ((ParamQs.getCVRQualifiers() | ArgQs.getCVRQualifiers())
889 == ParamQs.getCVRQualifiers());
892 /// \brief Compare types for equality with respect to possibly compatible
893 /// function types (noreturn adjustment, implicit calling conventions). If any
894 /// of parameter and argument is not a function, just perform type comparison.
896 /// \param Param the template parameter type.
898 /// \param Arg the argument type.
899 bool Sema::isSameOrCompatibleFunctionType(CanQualType Param,
901 const FunctionType *ParamFunction = Param->getAs<FunctionType>(),
902 *ArgFunction = Arg->getAs<FunctionType>();
904 // Just compare if not functions.
905 if (!ParamFunction || !ArgFunction)
908 // Noreturn adjustment.
909 QualType AdjustedParam;
910 if (IsNoReturnConversion(Param, Arg, AdjustedParam))
911 return Arg == Context.getCanonicalType(AdjustedParam);
913 // FIXME: Compatible calling conventions.
918 /// \brief Deduce the template arguments by comparing the parameter type and
919 /// the argument type (C++ [temp.deduct.type]).
921 /// \param S the semantic analysis object within which we are deducing
923 /// \param TemplateParams the template parameters that we are deducing
925 /// \param ParamIn the parameter type
927 /// \param ArgIn the argument type
929 /// \param Info information about the template argument deduction itself
931 /// \param Deduced the deduced template arguments
933 /// \param TDF bitwise OR of the TemplateDeductionFlags bits that describe
934 /// how template argument deduction is performed.
936 /// \param PartialOrdering Whether we're performing template argument deduction
937 /// in the context of partial ordering (C++0x [temp.deduct.partial]).
939 /// \returns the result of template argument deduction so far. Note that a
940 /// "success" result means that template argument deduction has not yet failed,
941 /// but it may still fail, later, for other reasons.
942 static Sema::TemplateDeductionResult
943 DeduceTemplateArgumentsByTypeMatch(Sema &S,
944 TemplateParameterList *TemplateParams,
945 QualType ParamIn, QualType ArgIn,
946 TemplateDeductionInfo &Info,
947 SmallVectorImpl<DeducedTemplateArgument> &Deduced,
949 bool PartialOrdering) {
950 // We only want to look at the canonical types, since typedefs and
951 // sugar are not part of template argument deduction.
952 QualType Param = S.Context.getCanonicalType(ParamIn);
953 QualType Arg = S.Context.getCanonicalType(ArgIn);
955 // If the argument type is a pack expansion, look at its pattern.
956 // This isn't explicitly called out
957 if (const PackExpansionType *ArgExpansion
958 = dyn_cast<PackExpansionType>(Arg))
959 Arg = ArgExpansion->getPattern();
961 if (PartialOrdering) {
962 // C++11 [temp.deduct.partial]p5:
963 // Before the partial ordering is done, certain transformations are
964 // performed on the types used for partial ordering:
965 // - If P is a reference type, P is replaced by the type referred to.
966 const ReferenceType *ParamRef = Param->getAs<ReferenceType>();
968 Param = ParamRef->getPointeeType();
970 // - If A is a reference type, A is replaced by the type referred to.
971 const ReferenceType *ArgRef = Arg->getAs<ReferenceType>();
973 Arg = ArgRef->getPointeeType();
975 if (ParamRef && ArgRef && S.Context.hasSameUnqualifiedType(Param, Arg)) {
976 // C++11 [temp.deduct.partial]p9:
977 // If, for a given type, deduction succeeds in both directions (i.e.,
978 // the types are identical after the transformations above) and both
979 // P and A were reference types [...]:
980 // - if [one type] was an lvalue reference and [the other type] was
981 // not, [the other type] is not considered to be at least as
982 // specialized as [the first type]
983 // - if [one type] is more cv-qualified than [the other type],
984 // [the other type] is not considered to be at least as specialized
985 // as [the first type]
986 // Objective-C ARC adds:
987 // - [one type] has non-trivial lifetime, [the other type] has
988 // __unsafe_unretained lifetime, and the types are otherwise
991 // A is "considered to be at least as specialized" as P iff deduction
992 // succeeds, so we model this as a deduction failure. Note that
993 // [the first type] is P and [the other type] is A here; the standard
994 // gets this backwards.
995 Qualifiers ParamQuals = Param.getQualifiers();
996 Qualifiers ArgQuals = Arg.getQualifiers();
997 if ((ParamRef->isLValueReferenceType() &&
998 !ArgRef->isLValueReferenceType()) ||
999 ParamQuals.isStrictSupersetOf(ArgQuals) ||
1000 (ParamQuals.hasNonTrivialObjCLifetime() &&
1001 ArgQuals.getObjCLifetime() == Qualifiers::OCL_ExplicitNone &&
1002 ParamQuals.withoutObjCLifetime() ==
1003 ArgQuals.withoutObjCLifetime())) {
1004 Info.FirstArg = TemplateArgument(ParamIn);
1005 Info.SecondArg = TemplateArgument(ArgIn);
1006 return Sema::TDK_NonDeducedMismatch;
1010 // C++11 [temp.deduct.partial]p7:
1011 // Remove any top-level cv-qualifiers:
1012 // - If P is a cv-qualified type, P is replaced by the cv-unqualified
1014 Param = Param.getUnqualifiedType();
1015 // - If A is a cv-qualified type, A is replaced by the cv-unqualified
1017 Arg = Arg.getUnqualifiedType();
1019 // C++0x [temp.deduct.call]p4 bullet 1:
1020 // - If the original P is a reference type, the deduced A (i.e., the type
1021 // referred to by the reference) can be more cv-qualified than the
1023 if (TDF & TDF_ParamWithReferenceType) {
1025 QualType UnqualParam = S.Context.getUnqualifiedArrayType(Param, Quals);
1026 Quals.setCVRQualifiers(Quals.getCVRQualifiers() &
1027 Arg.getCVRQualifiers());
1028 Param = S.Context.getQualifiedType(UnqualParam, Quals);
1031 if ((TDF & TDF_TopLevelParameterTypeList) && !Param->isFunctionType()) {
1032 // C++0x [temp.deduct.type]p10:
1033 // If P and A are function types that originated from deduction when
1034 // taking the address of a function template (14.8.2.2) or when deducing
1035 // template arguments from a function declaration (14.8.2.6) and Pi and
1036 // Ai are parameters of the top-level parameter-type-list of P and A,
1037 // respectively, Pi is adjusted if it is an rvalue reference to a
1038 // cv-unqualified template parameter and Ai is an lvalue reference, in
1039 // which case the type of Pi is changed to be the template parameter
1040 // type (i.e., T&& is changed to simply T). [ Note: As a result, when
1041 // Pi is T&& and Ai is X&, the adjusted Pi will be T, causing T to be
1042 // deduced as X&. - end note ]
1043 TDF &= ~TDF_TopLevelParameterTypeList;
1045 if (const RValueReferenceType *ParamRef
1046 = Param->getAs<RValueReferenceType>()) {
1047 if (isa<TemplateTypeParmType>(ParamRef->getPointeeType()) &&
1048 !ParamRef->getPointeeType().getQualifiers())
1049 if (Arg->isLValueReferenceType())
1050 Param = ParamRef->getPointeeType();
1055 // C++ [temp.deduct.type]p9:
1056 // A template type argument T, a template template argument TT or a
1057 // template non-type argument i can be deduced if P and A have one of
1058 // the following forms:
1062 if (const TemplateTypeParmType *TemplateTypeParm
1063 = Param->getAs<TemplateTypeParmType>()) {
1064 // Just skip any attempts to deduce from a placeholder type.
1065 if (Arg->isPlaceholderType())
1066 return Sema::TDK_Success;
1068 unsigned Index = TemplateTypeParm->getIndex();
1069 bool RecanonicalizeArg = false;
1071 // If the argument type is an array type, move the qualifiers up to the
1072 // top level, so they can be matched with the qualifiers on the parameter.
1073 if (isa<ArrayType>(Arg)) {
1075 Arg = S.Context.getUnqualifiedArrayType(Arg, Quals);
1077 Arg = S.Context.getQualifiedType(Arg, Quals);
1078 RecanonicalizeArg = true;
1082 // The argument type can not be less qualified than the parameter
1084 if (!(TDF & TDF_IgnoreQualifiers) &&
1085 hasInconsistentOrSupersetQualifiersOf(Param, Arg)) {
1086 Info.Param = cast<TemplateTypeParmDecl>(TemplateParams->getParam(Index));
1087 Info.FirstArg = TemplateArgument(Param);
1088 Info.SecondArg = TemplateArgument(Arg);
1089 return Sema::TDK_Underqualified;
1092 assert(TemplateTypeParm->getDepth() == 0 && "Can't deduce with depth > 0");
1093 assert(Arg != S.Context.OverloadTy && "Unresolved overloaded function");
1094 QualType DeducedType = Arg;
1096 // Remove any qualifiers on the parameter from the deduced type.
1097 // We checked the qualifiers for consistency above.
1098 Qualifiers DeducedQs = DeducedType.getQualifiers();
1099 Qualifiers ParamQs = Param.getQualifiers();
1100 DeducedQs.removeCVRQualifiers(ParamQs.getCVRQualifiers());
1101 if (ParamQs.hasObjCGCAttr())
1102 DeducedQs.removeObjCGCAttr();
1103 if (ParamQs.hasAddressSpace())
1104 DeducedQs.removeAddressSpace();
1105 if (ParamQs.hasObjCLifetime())
1106 DeducedQs.removeObjCLifetime();
1109 // If template deduction would produce a lifetime qualifier on a type
1110 // that is not a lifetime type, template argument deduction fails.
1111 if (ParamQs.hasObjCLifetime() && !DeducedType->isObjCLifetimeType() &&
1112 !DeducedType->isDependentType()) {
1113 Info.Param = cast<TemplateTypeParmDecl>(TemplateParams->getParam(Index));
1114 Info.FirstArg = TemplateArgument(Param);
1115 Info.SecondArg = TemplateArgument(Arg);
1116 return Sema::TDK_Underqualified;
1120 // If template deduction would produce an argument type with lifetime type
1121 // but no lifetime qualifier, the __strong lifetime qualifier is inferred.
1122 if (S.getLangOpts().ObjCAutoRefCount &&
1123 DeducedType->isObjCLifetimeType() &&
1124 !DeducedQs.hasObjCLifetime())
1125 DeducedQs.setObjCLifetime(Qualifiers::OCL_Strong);
1127 DeducedType = S.Context.getQualifiedType(DeducedType.getUnqualifiedType(),
1130 if (RecanonicalizeArg)
1131 DeducedType = S.Context.getCanonicalType(DeducedType);
1133 DeducedTemplateArgument NewDeduced(DeducedType);
1134 DeducedTemplateArgument Result = checkDeducedTemplateArguments(S.Context,
1137 if (Result.isNull()) {
1138 Info.Param = cast<TemplateTypeParmDecl>(TemplateParams->getParam(Index));
1139 Info.FirstArg = Deduced[Index];
1140 Info.SecondArg = NewDeduced;
1141 return Sema::TDK_Inconsistent;
1144 Deduced[Index] = Result;
1145 return Sema::TDK_Success;
1148 // Set up the template argument deduction information for a failure.
1149 Info.FirstArg = TemplateArgument(ParamIn);
1150 Info.SecondArg = TemplateArgument(ArgIn);
1152 // If the parameter is an already-substituted template parameter
1153 // pack, do nothing: we don't know which of its arguments to look
1154 // at, so we have to wait until all of the parameter packs in this
1155 // expansion have arguments.
1156 if (isa<SubstTemplateTypeParmPackType>(Param))
1157 return Sema::TDK_Success;
1159 // Check the cv-qualifiers on the parameter and argument types.
1160 CanQualType CanParam = S.Context.getCanonicalType(Param);
1161 CanQualType CanArg = S.Context.getCanonicalType(Arg);
1162 if (!(TDF & TDF_IgnoreQualifiers)) {
1163 if (TDF & TDF_ParamWithReferenceType) {
1164 if (hasInconsistentOrSupersetQualifiersOf(Param, Arg))
1165 return Sema::TDK_NonDeducedMismatch;
1166 } else if (!IsPossiblyOpaquelyQualifiedType(Param)) {
1167 if (Param.getCVRQualifiers() != Arg.getCVRQualifiers())
1168 return Sema::TDK_NonDeducedMismatch;
1171 // If the parameter type is not dependent, there is nothing to deduce.
1172 if (!Param->isDependentType()) {
1173 if (!(TDF & TDF_SkipNonDependent)) {
1174 bool NonDeduced = (TDF & TDF_InOverloadResolution)?
1175 !S.isSameOrCompatibleFunctionType(CanParam, CanArg) :
1178 return Sema::TDK_NonDeducedMismatch;
1181 return Sema::TDK_Success;
1183 } else if (!Param->isDependentType()) {
1184 CanQualType ParamUnqualType = CanParam.getUnqualifiedType(),
1185 ArgUnqualType = CanArg.getUnqualifiedType();
1186 bool Success = (TDF & TDF_InOverloadResolution)?
1187 S.isSameOrCompatibleFunctionType(ParamUnqualType,
1189 ParamUnqualType == ArgUnqualType;
1191 return Sema::TDK_Success;
1194 switch (Param->getTypeClass()) {
1195 // Non-canonical types cannot appear here.
1196 #define NON_CANONICAL_TYPE(Class, Base) \
1197 case Type::Class: llvm_unreachable("deducing non-canonical type: " #Class);
1198 #define TYPE(Class, Base)
1199 #include "clang/AST/TypeNodes.def"
1201 case Type::TemplateTypeParm:
1202 case Type::SubstTemplateTypeParmPack:
1203 llvm_unreachable("Type nodes handled above");
1205 // These types cannot be dependent, so simply check whether the types are
1208 case Type::VariableArray:
1210 case Type::FunctionNoProto:
1213 case Type::ObjCObject:
1214 case Type::ObjCInterface:
1215 case Type::ObjCObjectPointer: {
1216 if (TDF & TDF_SkipNonDependent)
1217 return Sema::TDK_Success;
1219 if (TDF & TDF_IgnoreQualifiers) {
1220 Param = Param.getUnqualifiedType();
1221 Arg = Arg.getUnqualifiedType();
1224 return Param == Arg? Sema::TDK_Success : Sema::TDK_NonDeducedMismatch;
1227 // _Complex T [placeholder extension]
1229 if (const ComplexType *ComplexArg = Arg->getAs<ComplexType>())
1230 return DeduceTemplateArgumentsByTypeMatch(S, TemplateParams,
1231 cast<ComplexType>(Param)->getElementType(),
1232 ComplexArg->getElementType(),
1233 Info, Deduced, TDF);
1235 return Sema::TDK_NonDeducedMismatch;
1237 // _Atomic T [extension]
1239 if (const AtomicType *AtomicArg = Arg->getAs<AtomicType>())
1240 return DeduceTemplateArgumentsByTypeMatch(S, TemplateParams,
1241 cast<AtomicType>(Param)->getValueType(),
1242 AtomicArg->getValueType(),
1243 Info, Deduced, TDF);
1245 return Sema::TDK_NonDeducedMismatch;
1248 case Type::Pointer: {
1249 QualType PointeeType;
1250 if (const PointerType *PointerArg = Arg->getAs<PointerType>()) {
1251 PointeeType = PointerArg->getPointeeType();
1252 } else if (const ObjCObjectPointerType *PointerArg
1253 = Arg->getAs<ObjCObjectPointerType>()) {
1254 PointeeType = PointerArg->getPointeeType();
1256 return Sema::TDK_NonDeducedMismatch;
1259 unsigned SubTDF = TDF & (TDF_IgnoreQualifiers | TDF_DerivedClass);
1260 return DeduceTemplateArgumentsByTypeMatch(S, TemplateParams,
1261 cast<PointerType>(Param)->getPointeeType(),
1263 Info, Deduced, SubTDF);
1267 case Type::LValueReference: {
1268 const LValueReferenceType *ReferenceArg =
1269 Arg->getAs<LValueReferenceType>();
1271 return Sema::TDK_NonDeducedMismatch;
1273 return DeduceTemplateArgumentsByTypeMatch(S, TemplateParams,
1274 cast<LValueReferenceType>(Param)->getPointeeType(),
1275 ReferenceArg->getPointeeType(), Info, Deduced, 0);
1279 case Type::RValueReference: {
1280 const RValueReferenceType *ReferenceArg =
1281 Arg->getAs<RValueReferenceType>();
1283 return Sema::TDK_NonDeducedMismatch;
1285 return DeduceTemplateArgumentsByTypeMatch(S, TemplateParams,
1286 cast<RValueReferenceType>(Param)->getPointeeType(),
1287 ReferenceArg->getPointeeType(),
1291 // T [] (implied, but not stated explicitly)
1292 case Type::IncompleteArray: {
1293 const IncompleteArrayType *IncompleteArrayArg =
1294 S.Context.getAsIncompleteArrayType(Arg);
1295 if (!IncompleteArrayArg)
1296 return Sema::TDK_NonDeducedMismatch;
1298 unsigned SubTDF = TDF & TDF_IgnoreQualifiers;
1299 return DeduceTemplateArgumentsByTypeMatch(S, TemplateParams,
1300 S.Context.getAsIncompleteArrayType(Param)->getElementType(),
1301 IncompleteArrayArg->getElementType(),
1302 Info, Deduced, SubTDF);
1305 // T [integer-constant]
1306 case Type::ConstantArray: {
1307 const ConstantArrayType *ConstantArrayArg =
1308 S.Context.getAsConstantArrayType(Arg);
1309 if (!ConstantArrayArg)
1310 return Sema::TDK_NonDeducedMismatch;
1312 const ConstantArrayType *ConstantArrayParm =
1313 S.Context.getAsConstantArrayType(Param);
1314 if (ConstantArrayArg->getSize() != ConstantArrayParm->getSize())
1315 return Sema::TDK_NonDeducedMismatch;
1317 unsigned SubTDF = TDF & TDF_IgnoreQualifiers;
1318 return DeduceTemplateArgumentsByTypeMatch(S, TemplateParams,
1319 ConstantArrayParm->getElementType(),
1320 ConstantArrayArg->getElementType(),
1321 Info, Deduced, SubTDF);
1325 case Type::DependentSizedArray: {
1326 const ArrayType *ArrayArg = S.Context.getAsArrayType(Arg);
1328 return Sema::TDK_NonDeducedMismatch;
1330 unsigned SubTDF = TDF & TDF_IgnoreQualifiers;
1332 // Check the element type of the arrays
1333 const DependentSizedArrayType *DependentArrayParm
1334 = S.Context.getAsDependentSizedArrayType(Param);
1335 if (Sema::TemplateDeductionResult Result
1336 = DeduceTemplateArgumentsByTypeMatch(S, TemplateParams,
1337 DependentArrayParm->getElementType(),
1338 ArrayArg->getElementType(),
1339 Info, Deduced, SubTDF))
1342 // Determine the array bound is something we can deduce.
1343 NonTypeTemplateParmDecl *NTTP
1344 = getDeducedParameterFromExpr(DependentArrayParm->getSizeExpr());
1346 return Sema::TDK_Success;
1348 // We can perform template argument deduction for the given non-type
1349 // template parameter.
1350 assert(NTTP->getDepth() == 0 &&
1351 "Cannot deduce non-type template argument at depth > 0");
1352 if (const ConstantArrayType *ConstantArrayArg
1353 = dyn_cast<ConstantArrayType>(ArrayArg)) {
1354 llvm::APSInt Size(ConstantArrayArg->getSize());
1355 return DeduceNonTypeTemplateArgument(S, NTTP, Size,
1356 S.Context.getSizeType(),
1357 /*ArrayBound=*/true,
1360 if (const DependentSizedArrayType *DependentArrayArg
1361 = dyn_cast<DependentSizedArrayType>(ArrayArg))
1362 if (DependentArrayArg->getSizeExpr())
1363 return DeduceNonTypeTemplateArgument(S, NTTP,
1364 DependentArrayArg->getSizeExpr(),
1367 // Incomplete type does not match a dependently-sized array type
1368 return Sema::TDK_NonDeducedMismatch;
1374 case Type::FunctionProto: {
1375 unsigned SubTDF = TDF & TDF_TopLevelParameterTypeList;
1376 const FunctionProtoType *FunctionProtoArg =
1377 dyn_cast<FunctionProtoType>(Arg);
1378 if (!FunctionProtoArg)
1379 return Sema::TDK_NonDeducedMismatch;
1381 const FunctionProtoType *FunctionProtoParam =
1382 cast<FunctionProtoType>(Param);
1384 if (FunctionProtoParam->getTypeQuals()
1385 != FunctionProtoArg->getTypeQuals() ||
1386 FunctionProtoParam->getRefQualifier()
1387 != FunctionProtoArg->getRefQualifier() ||
1388 FunctionProtoParam->isVariadic() != FunctionProtoArg->isVariadic())
1389 return Sema::TDK_NonDeducedMismatch;
1391 // Check return types.
1392 if (Sema::TemplateDeductionResult Result =
1393 DeduceTemplateArgumentsByTypeMatch(
1394 S, TemplateParams, FunctionProtoParam->getReturnType(),
1395 FunctionProtoArg->getReturnType(), Info, Deduced, 0))
1398 return DeduceTemplateArguments(
1399 S, TemplateParams, FunctionProtoParam->param_type_begin(),
1400 FunctionProtoParam->getNumParams(),
1401 FunctionProtoArg->param_type_begin(),
1402 FunctionProtoArg->getNumParams(), Info, Deduced, SubTDF);
1405 case Type::InjectedClassName: {
1406 // Treat a template's injected-class-name as if the template
1407 // specialization type had been used.
1408 Param = cast<InjectedClassNameType>(Param)
1409 ->getInjectedSpecializationType();
1410 assert(isa<TemplateSpecializationType>(Param) &&
1411 "injected class name is not a template specialization type");
1415 // template-name<T> (where template-name refers to a class template)
1420 case Type::TemplateSpecialization: {
1421 const TemplateSpecializationType *SpecParam
1422 = cast<TemplateSpecializationType>(Param);
1424 // Try to deduce template arguments from the template-id.
1425 Sema::TemplateDeductionResult Result
1426 = DeduceTemplateArguments(S, TemplateParams, SpecParam, Arg,
1429 if (Result && (TDF & TDF_DerivedClass)) {
1430 // C++ [temp.deduct.call]p3b3:
1431 // If P is a class, and P has the form template-id, then A can be a
1432 // derived class of the deduced A. Likewise, if P is a pointer to a
1433 // class of the form template-id, A can be a pointer to a derived
1434 // class pointed to by the deduced A.
1436 // More importantly:
1437 // These alternatives are considered only if type deduction would
1439 if (const RecordType *RecordT = Arg->getAs<RecordType>()) {
1440 // We cannot inspect base classes as part of deduction when the type
1441 // is incomplete, so either instantiate any templates necessary to
1442 // complete the type, or skip over it if it cannot be completed.
1443 if (!S.isCompleteType(Info.getLocation(), Arg))
1446 // Use data recursion to crawl through the list of base classes.
1447 // Visited contains the set of nodes we have already visited, while
1448 // ToVisit is our stack of records that we still need to visit.
1449 llvm::SmallPtrSet<const RecordType *, 8> Visited;
1450 SmallVector<const RecordType *, 8> ToVisit;
1451 ToVisit.push_back(RecordT);
1452 bool Successful = false;
1453 SmallVector<DeducedTemplateArgument, 8> DeducedOrig(Deduced.begin(),
1455 while (!ToVisit.empty()) {
1456 // Retrieve the next class in the inheritance hierarchy.
1457 const RecordType *NextT = ToVisit.pop_back_val();
1459 // If we have already seen this type, skip it.
1460 if (!Visited.insert(NextT).second)
1463 // If this is a base class, try to perform template argument
1464 // deduction from it.
1465 if (NextT != RecordT) {
1466 TemplateDeductionInfo BaseInfo(Info.getLocation());
1467 Sema::TemplateDeductionResult BaseResult
1468 = DeduceTemplateArguments(S, TemplateParams, SpecParam,
1469 QualType(NextT, 0), BaseInfo,
1472 // If template argument deduction for this base was successful,
1473 // note that we had some success. Otherwise, ignore any deductions
1474 // from this base class.
1475 if (BaseResult == Sema::TDK_Success) {
1477 DeducedOrig.clear();
1478 DeducedOrig.append(Deduced.begin(), Deduced.end());
1479 Info.Param = BaseInfo.Param;
1480 Info.FirstArg = BaseInfo.FirstArg;
1481 Info.SecondArg = BaseInfo.SecondArg;
1484 Deduced = DeducedOrig;
1487 // Visit base classes
1488 CXXRecordDecl *Next = cast<CXXRecordDecl>(NextT->getDecl());
1489 for (const auto &Base : Next->bases()) {
1490 assert(Base.getType()->isRecordType() &&
1491 "Base class that isn't a record?");
1492 ToVisit.push_back(Base.getType()->getAs<RecordType>());
1497 return Sema::TDK_Success;
1509 // type (type::*)(T)
1514 case Type::MemberPointer: {
1515 const MemberPointerType *MemPtrParam = cast<MemberPointerType>(Param);
1516 const MemberPointerType *MemPtrArg = dyn_cast<MemberPointerType>(Arg);
1518 return Sema::TDK_NonDeducedMismatch;
1520 QualType ParamPointeeType = MemPtrParam->getPointeeType();
1521 if (ParamPointeeType->isFunctionType())
1522 S.adjustMemberFunctionCC(ParamPointeeType, /*IsStatic=*/true,
1523 /*IsCtorOrDtor=*/false, Info.getLocation());
1524 QualType ArgPointeeType = MemPtrArg->getPointeeType();
1525 if (ArgPointeeType->isFunctionType())
1526 S.adjustMemberFunctionCC(ArgPointeeType, /*IsStatic=*/true,
1527 /*IsCtorOrDtor=*/false, Info.getLocation());
1529 if (Sema::TemplateDeductionResult Result
1530 = DeduceTemplateArgumentsByTypeMatch(S, TemplateParams,
1534 TDF & TDF_IgnoreQualifiers))
1537 return DeduceTemplateArgumentsByTypeMatch(S, TemplateParams,
1538 QualType(MemPtrParam->getClass(), 0),
1539 QualType(MemPtrArg->getClass(), 0),
1541 TDF & TDF_IgnoreQualifiers);
1544 // (clang extension)
1549 case Type::BlockPointer: {
1550 const BlockPointerType *BlockPtrParam = cast<BlockPointerType>(Param);
1551 const BlockPointerType *BlockPtrArg = dyn_cast<BlockPointerType>(Arg);
1554 return Sema::TDK_NonDeducedMismatch;
1556 return DeduceTemplateArgumentsByTypeMatch(S, TemplateParams,
1557 BlockPtrParam->getPointeeType(),
1558 BlockPtrArg->getPointeeType(),
1562 // (clang extension)
1564 // T __attribute__(((ext_vector_type(<integral constant>))))
1565 case Type::ExtVector: {
1566 const ExtVectorType *VectorParam = cast<ExtVectorType>(Param);
1567 if (const ExtVectorType *VectorArg = dyn_cast<ExtVectorType>(Arg)) {
1568 // Make sure that the vectors have the same number of elements.
1569 if (VectorParam->getNumElements() != VectorArg->getNumElements())
1570 return Sema::TDK_NonDeducedMismatch;
1572 // Perform deduction on the element types.
1573 return DeduceTemplateArgumentsByTypeMatch(S, TemplateParams,
1574 VectorParam->getElementType(),
1575 VectorArg->getElementType(),
1576 Info, Deduced, TDF);
1579 if (const DependentSizedExtVectorType *VectorArg
1580 = dyn_cast<DependentSizedExtVectorType>(Arg)) {
1581 // We can't check the number of elements, since the argument has a
1582 // dependent number of elements. This can only occur during partial
1585 // Perform deduction on the element types.
1586 return DeduceTemplateArgumentsByTypeMatch(S, TemplateParams,
1587 VectorParam->getElementType(),
1588 VectorArg->getElementType(),
1589 Info, Deduced, TDF);
1592 return Sema::TDK_NonDeducedMismatch;
1595 // (clang extension)
1597 // T __attribute__(((ext_vector_type(N))))
1598 case Type::DependentSizedExtVector: {
1599 const DependentSizedExtVectorType *VectorParam
1600 = cast<DependentSizedExtVectorType>(Param);
1602 if (const ExtVectorType *VectorArg = dyn_cast<ExtVectorType>(Arg)) {
1603 // Perform deduction on the element types.
1604 if (Sema::TemplateDeductionResult Result
1605 = DeduceTemplateArgumentsByTypeMatch(S, TemplateParams,
1606 VectorParam->getElementType(),
1607 VectorArg->getElementType(),
1608 Info, Deduced, TDF))
1611 // Perform deduction on the vector size, if we can.
1612 NonTypeTemplateParmDecl *NTTP
1613 = getDeducedParameterFromExpr(VectorParam->getSizeExpr());
1615 return Sema::TDK_Success;
1617 llvm::APSInt ArgSize(S.Context.getTypeSize(S.Context.IntTy), false);
1618 ArgSize = VectorArg->getNumElements();
1619 return DeduceNonTypeTemplateArgument(S, NTTP, ArgSize, S.Context.IntTy,
1620 false, Info, Deduced);
1623 if (const DependentSizedExtVectorType *VectorArg
1624 = dyn_cast<DependentSizedExtVectorType>(Arg)) {
1625 // Perform deduction on the element types.
1626 if (Sema::TemplateDeductionResult Result
1627 = DeduceTemplateArgumentsByTypeMatch(S, TemplateParams,
1628 VectorParam->getElementType(),
1629 VectorArg->getElementType(),
1630 Info, Deduced, TDF))
1633 // Perform deduction on the vector size, if we can.
1634 NonTypeTemplateParmDecl *NTTP
1635 = getDeducedParameterFromExpr(VectorParam->getSizeExpr());
1637 return Sema::TDK_Success;
1639 return DeduceNonTypeTemplateArgument(S, NTTP, VectorArg->getSizeExpr(),
1643 return Sema::TDK_NonDeducedMismatch;
1646 case Type::TypeOfExpr:
1648 case Type::DependentName:
1649 case Type::UnresolvedUsing:
1650 case Type::Decltype:
1651 case Type::UnaryTransform:
1653 case Type::DependentTemplateSpecialization:
1654 case Type::PackExpansion:
1655 // No template argument deduction for these types
1656 return Sema::TDK_Success;
1659 llvm_unreachable("Invalid Type Class!");
1662 static Sema::TemplateDeductionResult
1663 DeduceTemplateArguments(Sema &S,
1664 TemplateParameterList *TemplateParams,
1665 const TemplateArgument &Param,
1666 TemplateArgument Arg,
1667 TemplateDeductionInfo &Info,
1668 SmallVectorImpl<DeducedTemplateArgument> &Deduced) {
1669 // If the template argument is a pack expansion, perform template argument
1670 // deduction against the pattern of that expansion. This only occurs during
1671 // partial ordering.
1672 if (Arg.isPackExpansion())
1673 Arg = Arg.getPackExpansionPattern();
1675 switch (Param.getKind()) {
1676 case TemplateArgument::Null:
1677 llvm_unreachable("Null template argument in parameter list");
1679 case TemplateArgument::Type:
1680 if (Arg.getKind() == TemplateArgument::Type)
1681 return DeduceTemplateArgumentsByTypeMatch(S, TemplateParams,
1685 Info.FirstArg = Param;
1686 Info.SecondArg = Arg;
1687 return Sema::TDK_NonDeducedMismatch;
1689 case TemplateArgument::Template:
1690 if (Arg.getKind() == TemplateArgument::Template)
1691 return DeduceTemplateArguments(S, TemplateParams,
1692 Param.getAsTemplate(),
1693 Arg.getAsTemplate(), Info, Deduced);
1694 Info.FirstArg = Param;
1695 Info.SecondArg = Arg;
1696 return Sema::TDK_NonDeducedMismatch;
1698 case TemplateArgument::TemplateExpansion:
1699 llvm_unreachable("caller should handle pack expansions");
1701 case TemplateArgument::Declaration:
1702 if (Arg.getKind() == TemplateArgument::Declaration &&
1703 isSameDeclaration(Param.getAsDecl(), Arg.getAsDecl()))
1704 return Sema::TDK_Success;
1706 Info.FirstArg = Param;
1707 Info.SecondArg = Arg;
1708 return Sema::TDK_NonDeducedMismatch;
1710 case TemplateArgument::NullPtr:
1711 if (Arg.getKind() == TemplateArgument::NullPtr &&
1712 S.Context.hasSameType(Param.getNullPtrType(), Arg.getNullPtrType()))
1713 return Sema::TDK_Success;
1715 Info.FirstArg = Param;
1716 Info.SecondArg = Arg;
1717 return Sema::TDK_NonDeducedMismatch;
1719 case TemplateArgument::Integral:
1720 if (Arg.getKind() == TemplateArgument::Integral) {
1721 if (hasSameExtendedValue(Param.getAsIntegral(), Arg.getAsIntegral()))
1722 return Sema::TDK_Success;
1724 Info.FirstArg = Param;
1725 Info.SecondArg = Arg;
1726 return Sema::TDK_NonDeducedMismatch;
1729 if (Arg.getKind() == TemplateArgument::Expression) {
1730 Info.FirstArg = Param;
1731 Info.SecondArg = Arg;
1732 return Sema::TDK_NonDeducedMismatch;
1735 Info.FirstArg = Param;
1736 Info.SecondArg = Arg;
1737 return Sema::TDK_NonDeducedMismatch;
1739 case TemplateArgument::Expression: {
1740 if (NonTypeTemplateParmDecl *NTTP
1741 = getDeducedParameterFromExpr(Param.getAsExpr())) {
1742 if (Arg.getKind() == TemplateArgument::Integral)
1743 return DeduceNonTypeTemplateArgument(S, NTTP,
1744 Arg.getAsIntegral(),
1745 Arg.getIntegralType(),
1746 /*ArrayBound=*/false,
1748 if (Arg.getKind() == TemplateArgument::Expression)
1749 return DeduceNonTypeTemplateArgument(S, NTTP, Arg.getAsExpr(),
1751 if (Arg.getKind() == TemplateArgument::Declaration)
1752 return DeduceNonTypeTemplateArgument(S, NTTP, Arg.getAsDecl(),
1755 Info.FirstArg = Param;
1756 Info.SecondArg = Arg;
1757 return Sema::TDK_NonDeducedMismatch;
1760 // Can't deduce anything, but that's okay.
1761 return Sema::TDK_Success;
1763 case TemplateArgument::Pack:
1764 llvm_unreachable("Argument packs should be expanded by the caller!");
1767 llvm_unreachable("Invalid TemplateArgument Kind!");
1770 /// \brief Determine whether there is a template argument to be used for
1773 /// This routine "expands" argument packs in-place, overriding its input
1774 /// parameters so that \c Args[ArgIdx] will be the available template argument.
1776 /// \returns true if there is another template argument (which will be at
1777 /// \c Args[ArgIdx]), false otherwise.
1778 static bool hasTemplateArgumentForDeduction(const TemplateArgument *&Args,
1780 unsigned &NumArgs) {
1781 if (ArgIdx == NumArgs)
1784 const TemplateArgument &Arg = Args[ArgIdx];
1785 if (Arg.getKind() != TemplateArgument::Pack)
1788 assert(ArgIdx == NumArgs - 1 && "Pack not at the end of argument list?");
1789 Args = Arg.pack_begin();
1790 NumArgs = Arg.pack_size();
1792 return ArgIdx < NumArgs;
1795 /// \brief Determine whether the given set of template arguments has a pack
1796 /// expansion that is not the last template argument.
1797 static bool hasPackExpansionBeforeEnd(const TemplateArgument *Args,
1799 unsigned ArgIdx = 0;
1800 while (ArgIdx < NumArgs) {
1801 const TemplateArgument &Arg = Args[ArgIdx];
1803 // Unwrap argument packs.
1804 if (Args[ArgIdx].getKind() == TemplateArgument::Pack) {
1805 Args = Arg.pack_begin();
1806 NumArgs = Arg.pack_size();
1812 if (ArgIdx == NumArgs)
1815 if (Arg.isPackExpansion())
1822 static Sema::TemplateDeductionResult
1823 DeduceTemplateArguments(Sema &S,
1824 TemplateParameterList *TemplateParams,
1825 const TemplateArgument *Params, unsigned NumParams,
1826 const TemplateArgument *Args, unsigned NumArgs,
1827 TemplateDeductionInfo &Info,
1828 SmallVectorImpl<DeducedTemplateArgument> &Deduced) {
1829 // C++0x [temp.deduct.type]p9:
1830 // If the template argument list of P contains a pack expansion that is not
1831 // the last template argument, the entire template argument list is a
1832 // non-deduced context.
1833 if (hasPackExpansionBeforeEnd(Params, NumParams))
1834 return Sema::TDK_Success;
1836 // C++0x [temp.deduct.type]p9:
1837 // If P has a form that contains <T> or <i>, then each argument Pi of the
1838 // respective template argument list P is compared with the corresponding
1839 // argument Ai of the corresponding template argument list of A.
1840 unsigned ArgIdx = 0, ParamIdx = 0;
1841 for (; hasTemplateArgumentForDeduction(Params, ParamIdx, NumParams);
1843 if (!Params[ParamIdx].isPackExpansion()) {
1844 // The simple case: deduce template arguments by matching Pi and Ai.
1846 // Check whether we have enough arguments.
1847 if (!hasTemplateArgumentForDeduction(Args, ArgIdx, NumArgs))
1848 return Sema::TDK_Success;
1850 if (Args[ArgIdx].isPackExpansion()) {
1851 // FIXME: We follow the logic of C++0x [temp.deduct.type]p22 here,
1852 // but applied to pack expansions that are template arguments.
1853 return Sema::TDK_MiscellaneousDeductionFailure;
1856 // Perform deduction for this Pi/Ai pair.
1857 if (Sema::TemplateDeductionResult Result
1858 = DeduceTemplateArguments(S, TemplateParams,
1859 Params[ParamIdx], Args[ArgIdx],
1863 // Move to the next argument.
1868 // The parameter is a pack expansion.
1870 // C++0x [temp.deduct.type]p9:
1871 // If Pi is a pack expansion, then the pattern of Pi is compared with
1872 // each remaining argument in the template argument list of A. Each
1873 // comparison deduces template arguments for subsequent positions in the
1874 // template parameter packs expanded by Pi.
1875 TemplateArgument Pattern = Params[ParamIdx].getPackExpansionPattern();
1877 // FIXME: If there are no remaining arguments, we can bail out early
1878 // and set any deduced parameter packs to an empty argument pack.
1879 // The latter part of this is a (minor) correctness issue.
1881 // Prepare to deduce the packs within the pattern.
1882 PackDeductionScope PackScope(S, TemplateParams, Deduced, Info, Pattern);
1884 // Keep track of the deduced template arguments for each parameter pack
1885 // expanded by this pack expansion (the outer index) and for each
1886 // template argument (the inner SmallVectors).
1887 bool HasAnyArguments = false;
1888 for (; hasTemplateArgumentForDeduction(Args, ArgIdx, NumArgs); ++ArgIdx) {
1889 HasAnyArguments = true;
1891 // Deduce template arguments from the pattern.
1892 if (Sema::TemplateDeductionResult Result
1893 = DeduceTemplateArguments(S, TemplateParams, Pattern, Args[ArgIdx],
1897 PackScope.nextPackElement();
1900 // Build argument packs for each of the parameter packs expanded by this
1902 if (auto Result = PackScope.finish(HasAnyArguments))
1906 return Sema::TDK_Success;
1909 static Sema::TemplateDeductionResult
1910 DeduceTemplateArguments(Sema &S,
1911 TemplateParameterList *TemplateParams,
1912 const TemplateArgumentList &ParamList,
1913 const TemplateArgumentList &ArgList,
1914 TemplateDeductionInfo &Info,
1915 SmallVectorImpl<DeducedTemplateArgument> &Deduced) {
1916 return DeduceTemplateArguments(S, TemplateParams,
1917 ParamList.data(), ParamList.size(),
1918 ArgList.data(), ArgList.size(),
1922 /// \brief Determine whether two template arguments are the same.
1923 static bool isSameTemplateArg(ASTContext &Context,
1924 const TemplateArgument &X,
1925 const TemplateArgument &Y) {
1926 if (X.getKind() != Y.getKind())
1929 switch (X.getKind()) {
1930 case TemplateArgument::Null:
1931 llvm_unreachable("Comparing NULL template argument");
1933 case TemplateArgument::Type:
1934 return Context.getCanonicalType(X.getAsType()) ==
1935 Context.getCanonicalType(Y.getAsType());
1937 case TemplateArgument::Declaration:
1938 return isSameDeclaration(X.getAsDecl(), Y.getAsDecl());
1940 case TemplateArgument::NullPtr:
1941 return Context.hasSameType(X.getNullPtrType(), Y.getNullPtrType());
1943 case TemplateArgument::Template:
1944 case TemplateArgument::TemplateExpansion:
1945 return Context.getCanonicalTemplateName(
1946 X.getAsTemplateOrTemplatePattern()).getAsVoidPointer() ==
1947 Context.getCanonicalTemplateName(
1948 Y.getAsTemplateOrTemplatePattern()).getAsVoidPointer();
1950 case TemplateArgument::Integral:
1951 return X.getAsIntegral() == Y.getAsIntegral();
1953 case TemplateArgument::Expression: {
1954 llvm::FoldingSetNodeID XID, YID;
1955 X.getAsExpr()->Profile(XID, Context, true);
1956 Y.getAsExpr()->Profile(YID, Context, true);
1960 case TemplateArgument::Pack:
1961 if (X.pack_size() != Y.pack_size())
1964 for (TemplateArgument::pack_iterator XP = X.pack_begin(),
1965 XPEnd = X.pack_end(),
1966 YP = Y.pack_begin();
1967 XP != XPEnd; ++XP, ++YP)
1968 if (!isSameTemplateArg(Context, *XP, *YP))
1974 llvm_unreachable("Invalid TemplateArgument Kind!");
1977 /// \brief Allocate a TemplateArgumentLoc where all locations have
1978 /// been initialized to the given location.
1980 /// \param S The semantic analysis object.
1982 /// \param Arg The template argument we are producing template argument
1983 /// location information for.
1985 /// \param NTTPType For a declaration template argument, the type of
1986 /// the non-type template parameter that corresponds to this template
1989 /// \param Loc The source location to use for the resulting template
1991 static TemplateArgumentLoc
1992 getTrivialTemplateArgumentLoc(Sema &S,
1993 const TemplateArgument &Arg,
1995 SourceLocation Loc) {
1996 switch (Arg.getKind()) {
1997 case TemplateArgument::Null:
1998 llvm_unreachable("Can't get a NULL template argument here");
2000 case TemplateArgument::Type:
2001 return TemplateArgumentLoc(Arg,
2002 S.Context.getTrivialTypeSourceInfo(Arg.getAsType(), Loc));
2004 case TemplateArgument::Declaration: {
2006 = S.BuildExpressionFromDeclTemplateArgument(Arg, NTTPType, Loc)
2008 return TemplateArgumentLoc(TemplateArgument(E), E);
2011 case TemplateArgument::NullPtr: {
2013 = S.BuildExpressionFromDeclTemplateArgument(Arg, NTTPType, Loc)
2015 return TemplateArgumentLoc(TemplateArgument(NTTPType, /*isNullPtr*/true),
2019 case TemplateArgument::Integral: {
2021 = S.BuildExpressionFromIntegralTemplateArgument(Arg, Loc).getAs<Expr>();
2022 return TemplateArgumentLoc(TemplateArgument(E), E);
2025 case TemplateArgument::Template:
2026 case TemplateArgument::TemplateExpansion: {
2027 NestedNameSpecifierLocBuilder Builder;
2028 TemplateName Template = Arg.getAsTemplate();
2029 if (DependentTemplateName *DTN = Template.getAsDependentTemplateName())
2030 Builder.MakeTrivial(S.Context, DTN->getQualifier(), Loc);
2031 else if (QualifiedTemplateName *QTN =
2032 Template.getAsQualifiedTemplateName())
2033 Builder.MakeTrivial(S.Context, QTN->getQualifier(), Loc);
2035 if (Arg.getKind() == TemplateArgument::Template)
2036 return TemplateArgumentLoc(Arg,
2037 Builder.getWithLocInContext(S.Context),
2041 return TemplateArgumentLoc(Arg, Builder.getWithLocInContext(S.Context),
2045 case TemplateArgument::Expression:
2046 return TemplateArgumentLoc(Arg, Arg.getAsExpr());
2048 case TemplateArgument::Pack:
2049 return TemplateArgumentLoc(Arg, TemplateArgumentLocInfo());
2052 llvm_unreachable("Invalid TemplateArgument Kind!");
2056 /// \brief Convert the given deduced template argument and add it to the set of
2057 /// fully-converted template arguments.
2059 ConvertDeducedTemplateArgument(Sema &S, NamedDecl *Param,
2060 DeducedTemplateArgument Arg,
2061 NamedDecl *Template,
2063 unsigned ArgumentPackIndex,
2064 TemplateDeductionInfo &Info,
2065 bool InFunctionTemplate,
2066 SmallVectorImpl<TemplateArgument> &Output) {
2067 if (Arg.getKind() == TemplateArgument::Pack) {
2068 // This is a template argument pack, so check each of its arguments against
2069 // the template parameter.
2070 SmallVector<TemplateArgument, 2> PackedArgsBuilder;
2071 for (const auto &P : Arg.pack_elements()) {
2072 // When converting the deduced template argument, append it to the
2073 // general output list. We need to do this so that the template argument
2074 // checking logic has all of the prior template arguments available.
2075 DeducedTemplateArgument InnerArg(P);
2076 InnerArg.setDeducedFromArrayBound(Arg.wasDeducedFromArrayBound());
2077 if (ConvertDeducedTemplateArgument(S, Param, InnerArg, Template,
2078 NTTPType, PackedArgsBuilder.size(),
2079 Info, InFunctionTemplate, Output))
2082 // Move the converted template argument into our argument pack.
2083 PackedArgsBuilder.push_back(Output.pop_back_val());
2086 // Create the resulting argument pack.
2088 TemplateArgument::CreatePackCopy(S.Context, PackedArgsBuilder));
2092 // Convert the deduced template argument into a template
2093 // argument that we can check, almost as if the user had written
2094 // the template argument explicitly.
2095 TemplateArgumentLoc ArgLoc = getTrivialTemplateArgumentLoc(S, Arg, NTTPType,
2096 Info.getLocation());
2098 // Check the template argument, converting it as necessary.
2099 return S.CheckTemplateArgument(Param, ArgLoc,
2101 Template->getLocation(),
2102 Template->getSourceRange().getEnd(),
2106 ? (Arg.wasDeducedFromArrayBound()
2107 ? Sema::CTAK_DeducedFromArrayBound
2108 : Sema::CTAK_Deduced)
2109 : Sema::CTAK_Specified);
2112 /// Complete template argument deduction for a class template partial
2114 static Sema::TemplateDeductionResult
2115 FinishTemplateArgumentDeduction(Sema &S,
2116 ClassTemplatePartialSpecializationDecl *Partial,
2117 const TemplateArgumentList &TemplateArgs,
2118 SmallVectorImpl<DeducedTemplateArgument> &Deduced,
2119 TemplateDeductionInfo &Info) {
2120 // Unevaluated SFINAE context.
2121 EnterExpressionEvaluationContext Unevaluated(S, Sema::Unevaluated);
2122 Sema::SFINAETrap Trap(S);
2124 Sema::ContextRAII SavedContext(S, Partial);
2126 // C++ [temp.deduct.type]p2:
2127 // [...] or if any template argument remains neither deduced nor
2128 // explicitly specified, template argument deduction fails.
2129 SmallVector<TemplateArgument, 4> Builder;
2130 TemplateParameterList *PartialParams = Partial->getTemplateParameters();
2131 for (unsigned I = 0, N = PartialParams->size(); I != N; ++I) {
2132 NamedDecl *Param = PartialParams->getParam(I);
2133 if (Deduced[I].isNull()) {
2134 Info.Param = makeTemplateParameter(Param);
2135 return Sema::TDK_Incomplete;
2138 // We have deduced this argument, so it still needs to be
2139 // checked and converted.
2141 // First, for a non-type template parameter type that is
2142 // initialized by a declaration, we need the type of the
2143 // corresponding non-type template parameter.
2145 if (NonTypeTemplateParmDecl *NTTP
2146 = dyn_cast<NonTypeTemplateParmDecl>(Param)) {
2147 NTTPType = NTTP->getType();
2148 if (NTTPType->isDependentType()) {
2149 TemplateArgumentList TemplateArgs(TemplateArgumentList::OnStack,
2150 Builder.data(), Builder.size());
2151 NTTPType = S.SubstType(NTTPType,
2152 MultiLevelTemplateArgumentList(TemplateArgs),
2153 NTTP->getLocation(),
2154 NTTP->getDeclName());
2155 if (NTTPType.isNull()) {
2156 Info.Param = makeTemplateParameter(Param);
2157 // FIXME: These template arguments are temporary. Free them!
2158 Info.reset(TemplateArgumentList::CreateCopy(S.Context,
2161 return Sema::TDK_SubstitutionFailure;
2166 if (ConvertDeducedTemplateArgument(S, Param, Deduced[I],
2167 Partial, NTTPType, 0, Info, false,
2169 Info.Param = makeTemplateParameter(Param);
2170 // FIXME: These template arguments are temporary. Free them!
2171 Info.reset(TemplateArgumentList::CreateCopy(S.Context, Builder.data(),
2173 return Sema::TDK_SubstitutionFailure;
2177 // Form the template argument list from the deduced template arguments.
2178 TemplateArgumentList *DeducedArgumentList
2179 = TemplateArgumentList::CreateCopy(S.Context, Builder.data(),
2182 Info.reset(DeducedArgumentList);
2184 // Substitute the deduced template arguments into the template
2185 // arguments of the class template partial specialization, and
2186 // verify that the instantiated template arguments are both valid
2187 // and are equivalent to the template arguments originally provided
2188 // to the class template.
2189 LocalInstantiationScope InstScope(S);
2190 ClassTemplateDecl *ClassTemplate = Partial->getSpecializedTemplate();
2191 const ASTTemplateArgumentListInfo *PartialTemplArgInfo
2192 = Partial->getTemplateArgsAsWritten();
2193 const TemplateArgumentLoc *PartialTemplateArgs
2194 = PartialTemplArgInfo->getTemplateArgs();
2196 TemplateArgumentListInfo InstArgs(PartialTemplArgInfo->LAngleLoc,
2197 PartialTemplArgInfo->RAngleLoc);
2199 if (S.Subst(PartialTemplateArgs, PartialTemplArgInfo->NumTemplateArgs,
2200 InstArgs, MultiLevelTemplateArgumentList(*DeducedArgumentList))) {
2201 unsigned ArgIdx = InstArgs.size(), ParamIdx = ArgIdx;
2202 if (ParamIdx >= Partial->getTemplateParameters()->size())
2203 ParamIdx = Partial->getTemplateParameters()->size() - 1;
2206 = const_cast<NamedDecl *>(
2207 Partial->getTemplateParameters()->getParam(ParamIdx));
2208 Info.Param = makeTemplateParameter(Param);
2209 Info.FirstArg = PartialTemplateArgs[ArgIdx].getArgument();
2210 return Sema::TDK_SubstitutionFailure;
2213 SmallVector<TemplateArgument, 4> ConvertedInstArgs;
2214 if (S.CheckTemplateArgumentList(ClassTemplate, Partial->getLocation(),
2215 InstArgs, false, ConvertedInstArgs))
2216 return Sema::TDK_SubstitutionFailure;
2218 TemplateParameterList *TemplateParams
2219 = ClassTemplate->getTemplateParameters();
2220 for (unsigned I = 0, E = TemplateParams->size(); I != E; ++I) {
2221 TemplateArgument InstArg = ConvertedInstArgs.data()[I];
2222 if (!isSameTemplateArg(S.Context, TemplateArgs[I], InstArg)) {
2223 Info.Param = makeTemplateParameter(TemplateParams->getParam(I));
2224 Info.FirstArg = TemplateArgs[I];
2225 Info.SecondArg = InstArg;
2226 return Sema::TDK_NonDeducedMismatch;
2230 if (Trap.hasErrorOccurred())
2231 return Sema::TDK_SubstitutionFailure;
2233 return Sema::TDK_Success;
2236 /// \brief Perform template argument deduction to determine whether
2237 /// the given template arguments match the given class template
2238 /// partial specialization per C++ [temp.class.spec.match].
2239 Sema::TemplateDeductionResult
2240 Sema::DeduceTemplateArguments(ClassTemplatePartialSpecializationDecl *Partial,
2241 const TemplateArgumentList &TemplateArgs,
2242 TemplateDeductionInfo &Info) {
2243 if (Partial->isInvalidDecl())
2246 // C++ [temp.class.spec.match]p2:
2247 // A partial specialization matches a given actual template
2248 // argument list if the template arguments of the partial
2249 // specialization can be deduced from the actual template argument
2252 // Unevaluated SFINAE context.
2253 EnterExpressionEvaluationContext Unevaluated(*this, Sema::Unevaluated);
2254 SFINAETrap Trap(*this);
2256 SmallVector<DeducedTemplateArgument, 4> Deduced;
2257 Deduced.resize(Partial->getTemplateParameters()->size());
2258 if (TemplateDeductionResult Result
2259 = ::DeduceTemplateArguments(*this,
2260 Partial->getTemplateParameters(),
2261 Partial->getTemplateArgs(),
2262 TemplateArgs, Info, Deduced))
2265 SmallVector<TemplateArgument, 4> DeducedArgs(Deduced.begin(), Deduced.end());
2266 InstantiatingTemplate Inst(*this, Info.getLocation(), Partial, DeducedArgs,
2268 if (Inst.isInvalid())
2269 return TDK_InstantiationDepth;
2271 if (Trap.hasErrorOccurred())
2272 return Sema::TDK_SubstitutionFailure;
2274 return ::FinishTemplateArgumentDeduction(*this, Partial, TemplateArgs,
2278 /// Complete template argument deduction for a variable template partial
2280 /// TODO: Unify with ClassTemplatePartialSpecializationDecl version?
2281 /// May require unifying ClassTemplate(Partial)SpecializationDecl and
2282 /// VarTemplate(Partial)SpecializationDecl with a new data
2283 /// structure Template(Partial)SpecializationDecl, and
2284 /// using Template(Partial)SpecializationDecl as input type.
2285 static Sema::TemplateDeductionResult FinishTemplateArgumentDeduction(
2286 Sema &S, VarTemplatePartialSpecializationDecl *Partial,
2287 const TemplateArgumentList &TemplateArgs,
2288 SmallVectorImpl<DeducedTemplateArgument> &Deduced,
2289 TemplateDeductionInfo &Info) {
2290 // Unevaluated SFINAE context.
2291 EnterExpressionEvaluationContext Unevaluated(S, Sema::Unevaluated);
2292 Sema::SFINAETrap Trap(S);
2294 // C++ [temp.deduct.type]p2:
2295 // [...] or if any template argument remains neither deduced nor
2296 // explicitly specified, template argument deduction fails.
2297 SmallVector<TemplateArgument, 4> Builder;
2298 TemplateParameterList *PartialParams = Partial->getTemplateParameters();
2299 for (unsigned I = 0, N = PartialParams->size(); I != N; ++I) {
2300 NamedDecl *Param = PartialParams->getParam(I);
2301 if (Deduced[I].isNull()) {
2302 Info.Param = makeTemplateParameter(Param);
2303 return Sema::TDK_Incomplete;
2306 // We have deduced this argument, so it still needs to be
2307 // checked and converted.
2309 // First, for a non-type template parameter type that is
2310 // initialized by a declaration, we need the type of the
2311 // corresponding non-type template parameter.
2313 if (NonTypeTemplateParmDecl *NTTP =
2314 dyn_cast<NonTypeTemplateParmDecl>(Param)) {
2315 NTTPType = NTTP->getType();
2316 if (NTTPType->isDependentType()) {
2317 TemplateArgumentList TemplateArgs(TemplateArgumentList::OnStack,
2318 Builder.data(), Builder.size());
2320 S.SubstType(NTTPType, MultiLevelTemplateArgumentList(TemplateArgs),
2321 NTTP->getLocation(), NTTP->getDeclName());
2322 if (NTTPType.isNull()) {
2323 Info.Param = makeTemplateParameter(Param);
2324 // FIXME: These template arguments are temporary. Free them!
2325 Info.reset(TemplateArgumentList::CreateCopy(S.Context, Builder.data(),
2327 return Sema::TDK_SubstitutionFailure;
2332 if (ConvertDeducedTemplateArgument(S, Param, Deduced[I], Partial, NTTPType,
2333 0, Info, false, Builder)) {
2334 Info.Param = makeTemplateParameter(Param);
2335 // FIXME: These template arguments are temporary. Free them!
2336 Info.reset(TemplateArgumentList::CreateCopy(S.Context, Builder.data(),
2338 return Sema::TDK_SubstitutionFailure;
2342 // Form the template argument list from the deduced template arguments.
2343 TemplateArgumentList *DeducedArgumentList = TemplateArgumentList::CreateCopy(
2344 S.Context, Builder.data(), Builder.size());
2346 Info.reset(DeducedArgumentList);
2348 // Substitute the deduced template arguments into the template
2349 // arguments of the class template partial specialization, and
2350 // verify that the instantiated template arguments are both valid
2351 // and are equivalent to the template arguments originally provided
2352 // to the class template.
2353 LocalInstantiationScope InstScope(S);
2354 VarTemplateDecl *VarTemplate = Partial->getSpecializedTemplate();
2355 const ASTTemplateArgumentListInfo *PartialTemplArgInfo
2356 = Partial->getTemplateArgsAsWritten();
2357 const TemplateArgumentLoc *PartialTemplateArgs
2358 = PartialTemplArgInfo->getTemplateArgs();
2360 TemplateArgumentListInfo InstArgs(PartialTemplArgInfo->LAngleLoc,
2361 PartialTemplArgInfo->RAngleLoc);
2363 if (S.Subst(PartialTemplateArgs, PartialTemplArgInfo->NumTemplateArgs,
2364 InstArgs, MultiLevelTemplateArgumentList(*DeducedArgumentList))) {
2365 unsigned ArgIdx = InstArgs.size(), ParamIdx = ArgIdx;
2366 if (ParamIdx >= Partial->getTemplateParameters()->size())
2367 ParamIdx = Partial->getTemplateParameters()->size() - 1;
2369 Decl *Param = const_cast<NamedDecl *>(
2370 Partial->getTemplateParameters()->getParam(ParamIdx));
2371 Info.Param = makeTemplateParameter(Param);
2372 Info.FirstArg = PartialTemplateArgs[ArgIdx].getArgument();
2373 return Sema::TDK_SubstitutionFailure;
2375 SmallVector<TemplateArgument, 4> ConvertedInstArgs;
2376 if (S.CheckTemplateArgumentList(VarTemplate, Partial->getLocation(), InstArgs,
2377 false, ConvertedInstArgs))
2378 return Sema::TDK_SubstitutionFailure;
2380 TemplateParameterList *TemplateParams = VarTemplate->getTemplateParameters();
2381 for (unsigned I = 0, E = TemplateParams->size(); I != E; ++I) {
2382 TemplateArgument InstArg = ConvertedInstArgs.data()[I];
2383 if (!isSameTemplateArg(S.Context, TemplateArgs[I], InstArg)) {
2384 Info.Param = makeTemplateParameter(TemplateParams->getParam(I));
2385 Info.FirstArg = TemplateArgs[I];
2386 Info.SecondArg = InstArg;
2387 return Sema::TDK_NonDeducedMismatch;
2391 if (Trap.hasErrorOccurred())
2392 return Sema::TDK_SubstitutionFailure;
2394 return Sema::TDK_Success;
2397 /// \brief Perform template argument deduction to determine whether
2398 /// the given template arguments match the given variable template
2399 /// partial specialization per C++ [temp.class.spec.match].
2400 /// TODO: Unify with ClassTemplatePartialSpecializationDecl version?
2401 /// May require unifying ClassTemplate(Partial)SpecializationDecl and
2402 /// VarTemplate(Partial)SpecializationDecl with a new data
2403 /// structure Template(Partial)SpecializationDecl, and
2404 /// using Template(Partial)SpecializationDecl as input type.
2405 Sema::TemplateDeductionResult
2406 Sema::DeduceTemplateArguments(VarTemplatePartialSpecializationDecl *Partial,
2407 const TemplateArgumentList &TemplateArgs,
2408 TemplateDeductionInfo &Info) {
2409 if (Partial->isInvalidDecl())
2412 // C++ [temp.class.spec.match]p2:
2413 // A partial specialization matches a given actual template
2414 // argument list if the template arguments of the partial
2415 // specialization can be deduced from the actual template argument
2418 // Unevaluated SFINAE context.
2419 EnterExpressionEvaluationContext Unevaluated(*this, Sema::Unevaluated);
2420 SFINAETrap Trap(*this);
2422 SmallVector<DeducedTemplateArgument, 4> Deduced;
2423 Deduced.resize(Partial->getTemplateParameters()->size());
2424 if (TemplateDeductionResult Result = ::DeduceTemplateArguments(
2425 *this, Partial->getTemplateParameters(), Partial->getTemplateArgs(),
2426 TemplateArgs, Info, Deduced))
2429 SmallVector<TemplateArgument, 4> DeducedArgs(Deduced.begin(), Deduced.end());
2430 InstantiatingTemplate Inst(*this, Info.getLocation(), Partial, DeducedArgs,
2432 if (Inst.isInvalid())
2433 return TDK_InstantiationDepth;
2435 if (Trap.hasErrorOccurred())
2436 return Sema::TDK_SubstitutionFailure;
2438 return ::FinishTemplateArgumentDeduction(*this, Partial, TemplateArgs,
2442 /// \brief Determine whether the given type T is a simple-template-id type.
2443 static bool isSimpleTemplateIdType(QualType T) {
2444 if (const TemplateSpecializationType *Spec
2445 = T->getAs<TemplateSpecializationType>())
2446 return Spec->getTemplateName().getAsTemplateDecl() != nullptr;
2451 /// \brief Substitute the explicitly-provided template arguments into the
2452 /// given function template according to C++ [temp.arg.explicit].
2454 /// \param FunctionTemplate the function template into which the explicit
2455 /// template arguments will be substituted.
2457 /// \param ExplicitTemplateArgs the explicitly-specified template
2460 /// \param Deduced the deduced template arguments, which will be populated
2461 /// with the converted and checked explicit template arguments.
2463 /// \param ParamTypes will be populated with the instantiated function
2466 /// \param FunctionType if non-NULL, the result type of the function template
2467 /// will also be instantiated and the pointed-to value will be updated with
2468 /// the instantiated function type.
2470 /// \param Info if substitution fails for any reason, this object will be
2471 /// populated with more information about the failure.
2473 /// \returns TDK_Success if substitution was successful, or some failure
2475 Sema::TemplateDeductionResult
2476 Sema::SubstituteExplicitTemplateArguments(
2477 FunctionTemplateDecl *FunctionTemplate,
2478 TemplateArgumentListInfo &ExplicitTemplateArgs,
2479 SmallVectorImpl<DeducedTemplateArgument> &Deduced,
2480 SmallVectorImpl<QualType> &ParamTypes,
2481 QualType *FunctionType,
2482 TemplateDeductionInfo &Info) {
2483 FunctionDecl *Function = FunctionTemplate->getTemplatedDecl();
2484 TemplateParameterList *TemplateParams
2485 = FunctionTemplate->getTemplateParameters();
2487 if (ExplicitTemplateArgs.size() == 0) {
2488 // No arguments to substitute; just copy over the parameter types and
2489 // fill in the function type.
2490 for (auto P : Function->params())
2491 ParamTypes.push_back(P->getType());
2494 *FunctionType = Function->getType();
2498 // Unevaluated SFINAE context.
2499 EnterExpressionEvaluationContext Unevaluated(*this, Sema::Unevaluated);
2500 SFINAETrap Trap(*this);
2502 // C++ [temp.arg.explicit]p3:
2503 // Template arguments that are present shall be specified in the
2504 // declaration order of their corresponding template-parameters. The
2505 // template argument list shall not specify more template-arguments than
2506 // there are corresponding template-parameters.
2507 SmallVector<TemplateArgument, 4> Builder;
2509 // Enter a new template instantiation context where we check the
2510 // explicitly-specified template arguments against this function template,
2511 // and then substitute them into the function parameter types.
2512 SmallVector<TemplateArgument, 4> DeducedArgs(Deduced.begin(), Deduced.end());
2513 InstantiatingTemplate Inst(*this, Info.getLocation(), FunctionTemplate,
2515 ActiveTemplateInstantiation::ExplicitTemplateArgumentSubstitution,
2517 if (Inst.isInvalid())
2518 return TDK_InstantiationDepth;
2520 if (CheckTemplateArgumentList(FunctionTemplate,
2522 ExplicitTemplateArgs,
2524 Builder) || Trap.hasErrorOccurred()) {
2525 unsigned Index = Builder.size();
2526 if (Index >= TemplateParams->size())
2527 Index = TemplateParams->size() - 1;
2528 Info.Param = makeTemplateParameter(TemplateParams->getParam(Index));
2529 return TDK_InvalidExplicitArguments;
2532 // Form the template argument list from the explicitly-specified
2533 // template arguments.
2534 TemplateArgumentList *ExplicitArgumentList
2535 = TemplateArgumentList::CreateCopy(Context, Builder.data(), Builder.size());
2536 Info.reset(ExplicitArgumentList);
2538 // Template argument deduction and the final substitution should be
2539 // done in the context of the templated declaration. Explicit
2540 // argument substitution, on the other hand, needs to happen in the
2542 ContextRAII SavedContext(*this, FunctionTemplate->getTemplatedDecl());
2544 // If we deduced template arguments for a template parameter pack,
2545 // note that the template argument pack is partially substituted and record
2546 // the explicit template arguments. They'll be used as part of deduction
2547 // for this template parameter pack.
2548 for (unsigned I = 0, N = Builder.size(); I != N; ++I) {
2549 const TemplateArgument &Arg = Builder[I];
2550 if (Arg.getKind() == TemplateArgument::Pack) {
2551 CurrentInstantiationScope->SetPartiallySubstitutedPack(
2552 TemplateParams->getParam(I),
2559 const FunctionProtoType *Proto
2560 = Function->getType()->getAs<FunctionProtoType>();
2561 assert(Proto && "Function template does not have a prototype?");
2563 // Isolate our substituted parameters from our caller.
2564 LocalInstantiationScope InstScope(*this, /*MergeWithOuterScope*/true);
2566 // Instantiate the types of each of the function parameters given the
2567 // explicitly-specified template arguments. If the function has a trailing
2568 // return type, substitute it after the arguments to ensure we substitute
2569 // in lexical order.
2570 if (Proto->hasTrailingReturn()) {
2571 if (SubstParmTypes(Function->getLocation(),
2572 Function->param_begin(), Function->getNumParams(),
2573 MultiLevelTemplateArgumentList(*ExplicitArgumentList),
2575 return TDK_SubstitutionFailure;
2578 // Instantiate the return type.
2579 QualType ResultType;
2581 // C++11 [expr.prim.general]p3:
2582 // If a declaration declares a member function or member function
2583 // template of a class X, the expression this is a prvalue of type
2584 // "pointer to cv-qualifier-seq X" between the optional cv-qualifer-seq
2585 // and the end of the function-definition, member-declarator, or
2587 unsigned ThisTypeQuals = 0;
2588 CXXRecordDecl *ThisContext = nullptr;
2589 if (CXXMethodDecl *Method = dyn_cast<CXXMethodDecl>(Function)) {
2590 ThisContext = Method->getParent();
2591 ThisTypeQuals = Method->getTypeQualifiers();
2594 CXXThisScopeRAII ThisScope(*this, ThisContext, ThisTypeQuals,
2595 getLangOpts().CPlusPlus11);
2598 SubstType(Proto->getReturnType(),
2599 MultiLevelTemplateArgumentList(*ExplicitArgumentList),
2600 Function->getTypeSpecStartLoc(), Function->getDeclName());
2601 if (ResultType.isNull() || Trap.hasErrorOccurred())
2602 return TDK_SubstitutionFailure;
2605 // Instantiate the types of each of the function parameters given the
2606 // explicitly-specified template arguments if we didn't do so earlier.
2607 if (!Proto->hasTrailingReturn() &&
2608 SubstParmTypes(Function->getLocation(),
2609 Function->param_begin(), Function->getNumParams(),
2610 MultiLevelTemplateArgumentList(*ExplicitArgumentList),
2612 return TDK_SubstitutionFailure;
2615 *FunctionType = BuildFunctionType(ResultType, ParamTypes,
2616 Function->getLocation(),
2617 Function->getDeclName(),
2618 Proto->getExtProtoInfo());
2619 if (FunctionType->isNull() || Trap.hasErrorOccurred())
2620 return TDK_SubstitutionFailure;
2623 // C++ [temp.arg.explicit]p2:
2624 // Trailing template arguments that can be deduced (14.8.2) may be
2625 // omitted from the list of explicit template-arguments. If all of the
2626 // template arguments can be deduced, they may all be omitted; in this
2627 // case, the empty template argument list <> itself may also be omitted.
2629 // Take all of the explicitly-specified arguments and put them into
2630 // the set of deduced template arguments. Explicitly-specified
2631 // parameter packs, however, will be set to NULL since the deduction
2632 // mechanisms handle explicitly-specified argument packs directly.
2633 Deduced.reserve(TemplateParams->size());
2634 for (unsigned I = 0, N = ExplicitArgumentList->size(); I != N; ++I) {
2635 const TemplateArgument &Arg = ExplicitArgumentList->get(I);
2636 if (Arg.getKind() == TemplateArgument::Pack)
2637 Deduced.push_back(DeducedTemplateArgument());
2639 Deduced.push_back(Arg);
2645 /// \brief Check whether the deduced argument type for a call to a function
2646 /// template matches the actual argument type per C++ [temp.deduct.call]p4.
2648 CheckOriginalCallArgDeduction(Sema &S, Sema::OriginalCallArg OriginalArg,
2649 QualType DeducedA) {
2650 ASTContext &Context = S.Context;
2652 QualType A = OriginalArg.OriginalArgType;
2653 QualType OriginalParamType = OriginalArg.OriginalParamType;
2655 // Check for type equality (top-level cv-qualifiers are ignored).
2656 if (Context.hasSameUnqualifiedType(A, DeducedA))
2659 // Strip off references on the argument types; they aren't needed for
2660 // the following checks.
2661 if (const ReferenceType *DeducedARef = DeducedA->getAs<ReferenceType>())
2662 DeducedA = DeducedARef->getPointeeType();
2663 if (const ReferenceType *ARef = A->getAs<ReferenceType>())
2664 A = ARef->getPointeeType();
2666 // C++ [temp.deduct.call]p4:
2667 // [...] However, there are three cases that allow a difference:
2668 // - If the original P is a reference type, the deduced A (i.e., the
2669 // type referred to by the reference) can be more cv-qualified than
2670 // the transformed A.
2671 if (const ReferenceType *OriginalParamRef
2672 = OriginalParamType->getAs<ReferenceType>()) {
2673 // We don't want to keep the reference around any more.
2674 OriginalParamType = OriginalParamRef->getPointeeType();
2676 Qualifiers AQuals = A.getQualifiers();
2677 Qualifiers DeducedAQuals = DeducedA.getQualifiers();
2679 // Under Objective-C++ ARC, the deduced type may have implicitly
2680 // been given strong or (when dealing with a const reference)
2681 // unsafe_unretained lifetime. If so, update the original
2682 // qualifiers to include this lifetime.
2683 if (S.getLangOpts().ObjCAutoRefCount &&
2684 ((DeducedAQuals.getObjCLifetime() == Qualifiers::OCL_Strong &&
2685 AQuals.getObjCLifetime() == Qualifiers::OCL_None) ||
2686 (DeducedAQuals.hasConst() &&
2687 DeducedAQuals.getObjCLifetime() == Qualifiers::OCL_ExplicitNone))) {
2688 AQuals.setObjCLifetime(DeducedAQuals.getObjCLifetime());
2691 if (AQuals == DeducedAQuals) {
2692 // Qualifiers match; there's nothing to do.
2693 } else if (!DeducedAQuals.compatiblyIncludes(AQuals)) {
2696 // Qualifiers are compatible, so have the argument type adopt the
2697 // deduced argument type's qualifiers as if we had performed the
2698 // qualification conversion.
2699 A = Context.getQualifiedType(A.getUnqualifiedType(), DeducedAQuals);
2703 // - The transformed A can be another pointer or pointer to member
2704 // type that can be converted to the deduced A via a qualification
2707 // Also allow conversions which merely strip [[noreturn]] from function types
2708 // (recursively) as an extension.
2709 // FIXME: Currently, this doesn't play nicely with qualification conversions.
2710 bool ObjCLifetimeConversion = false;
2712 if ((A->isAnyPointerType() || A->isMemberPointerType()) &&
2713 (S.IsQualificationConversion(A, DeducedA, false,
2714 ObjCLifetimeConversion) ||
2715 S.IsNoReturnConversion(A, DeducedA, ResultTy)))
2719 // - If P is a class and P has the form simple-template-id, then the
2720 // transformed A can be a derived class of the deduced A. [...]
2721 // [...] Likewise, if P is a pointer to a class of the form
2722 // simple-template-id, the transformed A can be a pointer to a
2723 // derived class pointed to by the deduced A.
2724 if (const PointerType *OriginalParamPtr
2725 = OriginalParamType->getAs<PointerType>()) {
2726 if (const PointerType *DeducedAPtr = DeducedA->getAs<PointerType>()) {
2727 if (const PointerType *APtr = A->getAs<PointerType>()) {
2728 if (A->getPointeeType()->isRecordType()) {
2729 OriginalParamType = OriginalParamPtr->getPointeeType();
2730 DeducedA = DeducedAPtr->getPointeeType();
2731 A = APtr->getPointeeType();
2737 if (Context.hasSameUnqualifiedType(A, DeducedA))
2740 if (A->isRecordType() && isSimpleTemplateIdType(OriginalParamType) &&
2741 S.IsDerivedFrom(SourceLocation(), A, DeducedA))
2747 /// \brief Finish template argument deduction for a function template,
2748 /// checking the deduced template arguments for completeness and forming
2749 /// the function template specialization.
2751 /// \param OriginalCallArgs If non-NULL, the original call arguments against
2752 /// which the deduced argument types should be compared.
2753 Sema::TemplateDeductionResult
2754 Sema::FinishTemplateArgumentDeduction(FunctionTemplateDecl *FunctionTemplate,
2755 SmallVectorImpl<DeducedTemplateArgument> &Deduced,
2756 unsigned NumExplicitlySpecified,
2757 FunctionDecl *&Specialization,
2758 TemplateDeductionInfo &Info,
2759 SmallVectorImpl<OriginalCallArg> const *OriginalCallArgs,
2760 bool PartialOverloading) {
2761 TemplateParameterList *TemplateParams
2762 = FunctionTemplate->getTemplateParameters();
2764 // Unevaluated SFINAE context.
2765 EnterExpressionEvaluationContext Unevaluated(*this, Sema::Unevaluated);
2766 SFINAETrap Trap(*this);
2768 // Enter a new template instantiation context while we instantiate the
2769 // actual function declaration.
2770 SmallVector<TemplateArgument, 4> DeducedArgs(Deduced.begin(), Deduced.end());
2771 InstantiatingTemplate Inst(*this, Info.getLocation(), FunctionTemplate,
2773 ActiveTemplateInstantiation::DeducedTemplateArgumentSubstitution,
2775 if (Inst.isInvalid())
2776 return TDK_InstantiationDepth;
2778 ContextRAII SavedContext(*this, FunctionTemplate->getTemplatedDecl());
2780 // C++ [temp.deduct.type]p2:
2781 // [...] or if any template argument remains neither deduced nor
2782 // explicitly specified, template argument deduction fails.
2783 SmallVector<TemplateArgument, 4> Builder;
2784 for (unsigned I = 0, N = TemplateParams->size(); I != N; ++I) {
2785 NamedDecl *Param = TemplateParams->getParam(I);
2787 if (!Deduced[I].isNull()) {
2788 if (I < NumExplicitlySpecified) {
2789 // We have already fully type-checked and converted this
2790 // argument, because it was explicitly-specified. Just record the
2791 // presence of this argument.
2792 Builder.push_back(Deduced[I]);
2793 // We may have had explicitly-specified template arguments for a
2794 // template parameter pack (that may or may not have been extended
2795 // via additional deduced arguments).
2796 if (Param->isParameterPack() && CurrentInstantiationScope) {
2797 if (CurrentInstantiationScope->getPartiallySubstitutedPack() ==
2799 // Forget the partially-substituted pack; its substitution is now
2801 CurrentInstantiationScope->ResetPartiallySubstitutedPack();
2806 // We have deduced this argument, so it still needs to be
2807 // checked and converted.
2809 // First, for a non-type template parameter type that is
2810 // initialized by a declaration, we need the type of the
2811 // corresponding non-type template parameter.
2813 if (NonTypeTemplateParmDecl *NTTP
2814 = dyn_cast<NonTypeTemplateParmDecl>(Param)) {
2815 NTTPType = NTTP->getType();
2816 if (NTTPType->isDependentType()) {
2817 TemplateArgumentList TemplateArgs(TemplateArgumentList::OnStack,
2818 Builder.data(), Builder.size());
2819 NTTPType = SubstType(NTTPType,
2820 MultiLevelTemplateArgumentList(TemplateArgs),
2821 NTTP->getLocation(),
2822 NTTP->getDeclName());
2823 if (NTTPType.isNull()) {
2824 Info.Param = makeTemplateParameter(Param);
2825 // FIXME: These template arguments are temporary. Free them!
2826 Info.reset(TemplateArgumentList::CreateCopy(Context,
2829 return TDK_SubstitutionFailure;
2834 if (ConvertDeducedTemplateArgument(*this, Param, Deduced[I],
2835 FunctionTemplate, NTTPType, 0, Info,
2837 Info.Param = makeTemplateParameter(Param);
2838 // FIXME: These template arguments are temporary. Free them!
2839 Info.reset(TemplateArgumentList::CreateCopy(Context, Builder.data(),
2841 return TDK_SubstitutionFailure;
2847 // C++0x [temp.arg.explicit]p3:
2848 // A trailing template parameter pack (14.5.3) not otherwise deduced will
2849 // be deduced to an empty sequence of template arguments.
2850 // FIXME: Where did the word "trailing" come from?
2851 if (Param->isTemplateParameterPack()) {
2852 // We may have had explicitly-specified template arguments for this
2853 // template parameter pack. If so, our empty deduction extends the
2854 // explicitly-specified set (C++0x [temp.arg.explicit]p9).
2855 const TemplateArgument *ExplicitArgs;
2856 unsigned NumExplicitArgs;
2857 if (CurrentInstantiationScope &&
2858 CurrentInstantiationScope->getPartiallySubstitutedPack(&ExplicitArgs,
2861 Builder.push_back(TemplateArgument(
2862 llvm::makeArrayRef(ExplicitArgs, NumExplicitArgs)));
2864 // Forget the partially-substituted pack; it's substitution is now
2866 CurrentInstantiationScope->ResetPartiallySubstitutedPack();
2868 Builder.push_back(TemplateArgument::getEmptyPack());
2873 // Substitute into the default template argument, if available.
2874 bool HasDefaultArg = false;
2875 TemplateArgumentLoc DefArg
2876 = SubstDefaultTemplateArgumentIfAvailable(FunctionTemplate,
2877 FunctionTemplate->getLocation(),
2878 FunctionTemplate->getSourceRange().getEnd(),
2880 Builder, HasDefaultArg);
2882 // If there was no default argument, deduction is incomplete.
2883 if (DefArg.getArgument().isNull()) {
2884 Info.Param = makeTemplateParameter(
2885 const_cast<NamedDecl *>(TemplateParams->getParam(I)));
2886 Info.reset(TemplateArgumentList::CreateCopy(Context, Builder.data(),
2888 if (PartialOverloading) break;
2890 return HasDefaultArg ? TDK_SubstitutionFailure : TDK_Incomplete;
2893 // Check whether we can actually use the default argument.
2894 if (CheckTemplateArgument(Param, DefArg,
2896 FunctionTemplate->getLocation(),
2897 FunctionTemplate->getSourceRange().getEnd(),
2900 Info.Param = makeTemplateParameter(
2901 const_cast<NamedDecl *>(TemplateParams->getParam(I)));
2902 // FIXME: These template arguments are temporary. Free them!
2903 Info.reset(TemplateArgumentList::CreateCopy(Context, Builder.data(),
2905 return TDK_SubstitutionFailure;
2908 // If we get here, we successfully used the default template argument.
2911 // Form the template argument list from the deduced template arguments.
2912 TemplateArgumentList *DeducedArgumentList
2913 = TemplateArgumentList::CreateCopy(Context, Builder.data(), Builder.size());
2914 Info.reset(DeducedArgumentList);
2916 // Substitute the deduced template arguments into the function template
2917 // declaration to produce the function template specialization.
2918 DeclContext *Owner = FunctionTemplate->getDeclContext();
2919 if (FunctionTemplate->getFriendObjectKind())
2920 Owner = FunctionTemplate->getLexicalDeclContext();
2921 Specialization = cast_or_null<FunctionDecl>(
2922 SubstDecl(FunctionTemplate->getTemplatedDecl(), Owner,
2923 MultiLevelTemplateArgumentList(*DeducedArgumentList)));
2924 if (!Specialization || Specialization->isInvalidDecl())
2925 return TDK_SubstitutionFailure;
2927 assert(Specialization->getPrimaryTemplate()->getCanonicalDecl() ==
2928 FunctionTemplate->getCanonicalDecl());
2930 // If the template argument list is owned by the function template
2931 // specialization, release it.
2932 if (Specialization->getTemplateSpecializationArgs() == DeducedArgumentList &&
2933 !Trap.hasErrorOccurred())
2936 // There may have been an error that did not prevent us from constructing a
2937 // declaration. Mark the declaration invalid and return with a substitution
2939 if (Trap.hasErrorOccurred()) {
2940 Specialization->setInvalidDecl(true);
2941 return TDK_SubstitutionFailure;
2944 if (OriginalCallArgs) {
2945 // C++ [temp.deduct.call]p4:
2946 // In general, the deduction process attempts to find template argument
2947 // values that will make the deduced A identical to A (after the type A
2948 // is transformed as described above). [...]
2949 for (unsigned I = 0, N = OriginalCallArgs->size(); I != N; ++I) {
2950 OriginalCallArg OriginalArg = (*OriginalCallArgs)[I];
2951 unsigned ParamIdx = OriginalArg.ArgIdx;
2953 if (ParamIdx >= Specialization->getNumParams())
2956 QualType DeducedA = Specialization->getParamDecl(ParamIdx)->getType();
2957 if (CheckOriginalCallArgDeduction(*this, OriginalArg, DeducedA)) {
2958 Info.FirstArg = TemplateArgument(DeducedA);
2959 Info.SecondArg = TemplateArgument(OriginalArg.OriginalArgType);
2960 Info.CallArgIndex = OriginalArg.ArgIdx;
2961 return TDK_DeducedMismatch;
2966 // If we suppressed any diagnostics while performing template argument
2967 // deduction, and if we haven't already instantiated this declaration,
2968 // keep track of these diagnostics. They'll be emitted if this specialization
2969 // is actually used.
2970 if (Info.diag_begin() != Info.diag_end()) {
2971 SuppressedDiagnosticsMap::iterator
2972 Pos = SuppressedDiagnostics.find(Specialization->getCanonicalDecl());
2973 if (Pos == SuppressedDiagnostics.end())
2974 SuppressedDiagnostics[Specialization->getCanonicalDecl()]
2975 .append(Info.diag_begin(), Info.diag_end());
2981 /// Gets the type of a function for template-argument-deducton
2982 /// purposes when it's considered as part of an overload set.
2983 static QualType GetTypeOfFunction(Sema &S, const OverloadExpr::FindResult &R,
2985 // We may need to deduce the return type of the function now.
2986 if (S.getLangOpts().CPlusPlus14 && Fn->getReturnType()->isUndeducedType() &&
2987 S.DeduceReturnType(Fn, R.Expression->getExprLoc(), /*Diagnose*/ false))
2990 if (CXXMethodDecl *Method = dyn_cast<CXXMethodDecl>(Fn))
2991 if (Method->isInstance()) {
2992 // An instance method that's referenced in a form that doesn't
2993 // look like a member pointer is just invalid.
2994 if (!R.HasFormOfMemberPointer) return QualType();
2996 return S.Context.getMemberPointerType(Fn->getType(),
2997 S.Context.getTypeDeclType(Method->getParent()).getTypePtr());
3000 if (!R.IsAddressOfOperand) return Fn->getType();
3001 return S.Context.getPointerType(Fn->getType());
3004 /// Apply the deduction rules for overload sets.
3006 /// \return the null type if this argument should be treated as an
3007 /// undeduced context
3009 ResolveOverloadForDeduction(Sema &S, TemplateParameterList *TemplateParams,
3010 Expr *Arg, QualType ParamType,
3011 bool ParamWasReference) {
3013 OverloadExpr::FindResult R = OverloadExpr::find(Arg);
3015 OverloadExpr *Ovl = R.Expression;
3017 // C++0x [temp.deduct.call]p4
3019 if (ParamWasReference)
3020 TDF |= TDF_ParamWithReferenceType;
3021 if (R.IsAddressOfOperand)
3022 TDF |= TDF_IgnoreQualifiers;
3024 // C++0x [temp.deduct.call]p6:
3025 // When P is a function type, pointer to function type, or pointer
3026 // to member function type:
3028 if (!ParamType->isFunctionType() &&
3029 !ParamType->isFunctionPointerType() &&
3030 !ParamType->isMemberFunctionPointerType()) {
3031 if (Ovl->hasExplicitTemplateArgs()) {
3032 // But we can still look for an explicit specialization.
3033 if (FunctionDecl *ExplicitSpec
3034 = S.ResolveSingleFunctionTemplateSpecialization(Ovl))
3035 return GetTypeOfFunction(S, R, ExplicitSpec);
3041 // Gather the explicit template arguments, if any.
3042 TemplateArgumentListInfo ExplicitTemplateArgs;
3043 if (Ovl->hasExplicitTemplateArgs())
3044 Ovl->copyTemplateArgumentsInto(ExplicitTemplateArgs);
3046 for (UnresolvedSetIterator I = Ovl->decls_begin(),
3047 E = Ovl->decls_end(); I != E; ++I) {
3048 NamedDecl *D = (*I)->getUnderlyingDecl();
3050 if (FunctionTemplateDecl *FunTmpl = dyn_cast<FunctionTemplateDecl>(D)) {
3051 // - If the argument is an overload set containing one or more
3052 // function templates, the parameter is treated as a
3053 // non-deduced context.
3054 if (!Ovl->hasExplicitTemplateArgs())
3057 // Otherwise, see if we can resolve a function type
3058 FunctionDecl *Specialization = nullptr;
3059 TemplateDeductionInfo Info(Ovl->getNameLoc());
3060 if (S.DeduceTemplateArguments(FunTmpl, &ExplicitTemplateArgs,
3061 Specialization, Info))
3067 FunctionDecl *Fn = cast<FunctionDecl>(D);
3068 QualType ArgType = GetTypeOfFunction(S, R, Fn);
3069 if (ArgType.isNull()) continue;
3071 // Function-to-pointer conversion.
3072 if (!ParamWasReference && ParamType->isPointerType() &&
3073 ArgType->isFunctionType())
3074 ArgType = S.Context.getPointerType(ArgType);
3076 // - If the argument is an overload set (not containing function
3077 // templates), trial argument deduction is attempted using each
3078 // of the members of the set. If deduction succeeds for only one
3079 // of the overload set members, that member is used as the
3080 // argument value for the deduction. If deduction succeeds for
3081 // more than one member of the overload set the parameter is
3082 // treated as a non-deduced context.
3084 // We do all of this in a fresh context per C++0x [temp.deduct.type]p2:
3085 // Type deduction is done independently for each P/A pair, and
3086 // the deduced template argument values are then combined.
3087 // So we do not reject deductions which were made elsewhere.
3088 SmallVector<DeducedTemplateArgument, 8>
3089 Deduced(TemplateParams->size());
3090 TemplateDeductionInfo Info(Ovl->getNameLoc());
3091 Sema::TemplateDeductionResult Result
3092 = DeduceTemplateArgumentsByTypeMatch(S, TemplateParams, ParamType,
3093 ArgType, Info, Deduced, TDF);
3094 if (Result) continue;
3095 if (!Match.isNull()) return QualType();
3102 /// \brief Perform the adjustments to the parameter and argument types
3103 /// described in C++ [temp.deduct.call].
3105 /// \returns true if the caller should not attempt to perform any template
3106 /// argument deduction based on this P/A pair because the argument is an
3107 /// overloaded function set that could not be resolved.
3108 static bool AdjustFunctionParmAndArgTypesForDeduction(Sema &S,
3109 TemplateParameterList *TemplateParams,
3110 QualType &ParamType,
3114 // C++0x [temp.deduct.call]p3:
3115 // If P is a cv-qualified type, the top level cv-qualifiers of P's type
3116 // are ignored for type deduction.
3117 if (ParamType.hasQualifiers())
3118 ParamType = ParamType.getUnqualifiedType();
3120 // [...] If P is a reference type, the type referred to by P is
3121 // used for type deduction.
3122 const ReferenceType *ParamRefType = ParamType->getAs<ReferenceType>();
3124 ParamType = ParamRefType->getPointeeType();
3126 // Overload sets usually make this parameter an undeduced context,
3127 // but there are sometimes special circumstances. Typically
3128 // involving a template-id-expr.
3129 if (ArgType == S.Context.OverloadTy) {
3130 ArgType = ResolveOverloadForDeduction(S, TemplateParams,
3132 ParamRefType != nullptr);
3133 if (ArgType.isNull())
3138 // If the argument has incomplete array type, try to complete its type.
3139 if (ArgType->isIncompleteArrayType()) {
3140 S.completeExprArrayBound(Arg);
3141 ArgType = Arg->getType();
3144 // C++0x [temp.deduct.call]p3:
3145 // If P is an rvalue reference to a cv-unqualified template
3146 // parameter and the argument is an lvalue, the type "lvalue
3147 // reference to A" is used in place of A for type deduction.
3148 if (ParamRefType->isRValueReferenceType() &&
3149 !ParamType.getQualifiers() &&
3150 isa<TemplateTypeParmType>(ParamType) &&
3152 ArgType = S.Context.getLValueReferenceType(ArgType);
3154 // C++ [temp.deduct.call]p2:
3155 // If P is not a reference type:
3156 // - If A is an array type, the pointer type produced by the
3157 // array-to-pointer standard conversion (4.2) is used in place of
3158 // A for type deduction; otherwise,
3159 if (ArgType->isArrayType())
3160 ArgType = S.Context.getArrayDecayedType(ArgType);
3161 // - If A is a function type, the pointer type produced by the
3162 // function-to-pointer standard conversion (4.3) is used in place
3163 // of A for type deduction; otherwise,
3164 else if (ArgType->isFunctionType())
3165 ArgType = S.Context.getPointerType(ArgType);
3167 // - If A is a cv-qualified type, the top level cv-qualifiers of A's
3168 // type are ignored for type deduction.
3169 ArgType = ArgType.getUnqualifiedType();
3173 // C++0x [temp.deduct.call]p4:
3174 // In general, the deduction process attempts to find template argument
3175 // values that will make the deduced A identical to A (after the type A
3176 // is transformed as described above). [...]
3177 TDF = TDF_SkipNonDependent;
3179 // - If the original P is a reference type, the deduced A (i.e., the
3180 // type referred to by the reference) can be more cv-qualified than
3181 // the transformed A.
3183 TDF |= TDF_ParamWithReferenceType;
3184 // - The transformed A can be another pointer or pointer to member
3185 // type that can be converted to the deduced A via a qualification
3186 // conversion (4.4).
3187 if (ArgType->isPointerType() || ArgType->isMemberPointerType() ||
3188 ArgType->isObjCObjectPointerType())
3189 TDF |= TDF_IgnoreQualifiers;
3190 // - If P is a class and P has the form simple-template-id, then the
3191 // transformed A can be a derived class of the deduced A. Likewise,
3192 // if P is a pointer to a class of the form simple-template-id, the
3193 // transformed A can be a pointer to a derived class pointed to by
3195 if (isSimpleTemplateIdType(ParamType) ||
3196 (isa<PointerType>(ParamType) &&
3197 isSimpleTemplateIdType(
3198 ParamType->getAs<PointerType>()->getPointeeType())))
3199 TDF |= TDF_DerivedClass;
3205 hasDeducibleTemplateParameters(Sema &S, FunctionTemplateDecl *FunctionTemplate,
3208 static Sema::TemplateDeductionResult DeduceTemplateArgumentByListElement(
3209 Sema &S, TemplateParameterList *TemplateParams, QualType ParamType,
3210 Expr *Arg, TemplateDeductionInfo &Info,
3211 SmallVectorImpl<DeducedTemplateArgument> &Deduced, unsigned TDF);
3213 /// \brief Attempt template argument deduction from an initializer list
3214 /// deemed to be an argument in a function call.
3216 DeduceFromInitializerList(Sema &S, TemplateParameterList *TemplateParams,
3217 QualType AdjustedParamType, InitListExpr *ILE,
3218 TemplateDeductionInfo &Info,
3219 SmallVectorImpl<DeducedTemplateArgument> &Deduced,
3220 unsigned TDF, Sema::TemplateDeductionResult &Result) {
3222 // [temp.deduct.call] p1 (post CWG-1591)
3223 // If removing references and cv-qualifiers from P gives
3224 // std::initializer_list<P0> or P0[N] for some P0 and N and the argument is a
3225 // non-empty initializer list (8.5.4), then deduction is performed instead for
3226 // each element of the initializer list, taking P0 as a function template
3227 // parameter type and the initializer element as its argument, and in the
3228 // P0[N] case, if N is a non-type template parameter, N is deduced from the
3229 // length of the initializer list. Otherwise, an initializer list argument
3230 // causes the parameter to be considered a non-deduced context
3232 const bool IsConstSizedArray = AdjustedParamType->isConstantArrayType();
3234 const bool IsDependentSizedArray =
3235 !IsConstSizedArray && AdjustedParamType->isDependentSizedArrayType();
3237 QualType ElTy; // The element type of the std::initializer_list or the array.
3239 const bool IsSTDList = !IsConstSizedArray && !IsDependentSizedArray &&
3240 S.isStdInitializerList(AdjustedParamType, &ElTy);
3242 if (!IsConstSizedArray && !IsDependentSizedArray && !IsSTDList)
3245 Result = Sema::TDK_Success;
3246 // If we are not deducing against the 'T' in a std::initializer_list<T> then
3247 // deduce against the 'T' in T[N].
3248 if (ElTy.isNull()) {
3250 ElTy = S.Context.getAsArrayType(AdjustedParamType)->getElementType();
3252 // Deduction only needs to be done for dependent types.
3253 if (ElTy->isDependentType()) {
3254 for (Expr *E : ILE->inits()) {
3255 if ((Result = DeduceTemplateArgumentByListElement(S, TemplateParams, ElTy,
3256 E, Info, Deduced, TDF)))
3260 if (IsDependentSizedArray) {
3261 const DependentSizedArrayType *ArrTy =
3262 S.Context.getAsDependentSizedArrayType(AdjustedParamType);
3263 // Determine the array bound is something we can deduce.
3264 if (NonTypeTemplateParmDecl *NTTP =
3265 getDeducedParameterFromExpr(ArrTy->getSizeExpr())) {
3266 // We can perform template argument deduction for the given non-type
3267 // template parameter.
3268 assert(NTTP->getDepth() == 0 &&
3269 "Cannot deduce non-type template argument at depth > 0");
3270 llvm::APInt Size(S.Context.getIntWidth(NTTP->getType()),
3271 ILE->getNumInits());
3273 Result = DeduceNonTypeTemplateArgument(
3274 S, NTTP, llvm::APSInt(Size), NTTP->getType(),
3275 /*ArrayBound=*/true, Info, Deduced);
3281 /// \brief Perform template argument deduction by matching a parameter type
3282 /// against a single expression, where the expression is an element of
3283 /// an initializer list that was originally matched against a parameter
3284 /// of type \c initializer_list\<ParamType\>.
3285 static Sema::TemplateDeductionResult
3286 DeduceTemplateArgumentByListElement(Sema &S,
3287 TemplateParameterList *TemplateParams,
3288 QualType ParamType, Expr *Arg,
3289 TemplateDeductionInfo &Info,
3290 SmallVectorImpl<DeducedTemplateArgument> &Deduced,
3292 // Handle the case where an init list contains another init list as the
3294 if (InitListExpr *ILE = dyn_cast<InitListExpr>(Arg)) {
3295 Sema::TemplateDeductionResult Result;
3296 if (!DeduceFromInitializerList(S, TemplateParams,
3297 ParamType.getNonReferenceType(), ILE, Info,
3298 Deduced, TDF, Result))
3299 return Sema::TDK_Success; // Just ignore this expression.
3304 // For all other cases, just match by type.
3305 QualType ArgType = Arg->getType();
3306 if (AdjustFunctionParmAndArgTypesForDeduction(S, TemplateParams, ParamType,
3307 ArgType, Arg, TDF)) {
3308 Info.Expression = Arg;
3309 return Sema::TDK_FailedOverloadResolution;
3311 return DeduceTemplateArgumentsByTypeMatch(S, TemplateParams, ParamType,
3312 ArgType, Info, Deduced, TDF);
3315 /// \brief Perform template argument deduction from a function call
3316 /// (C++ [temp.deduct.call]).
3318 /// \param FunctionTemplate the function template for which we are performing
3319 /// template argument deduction.
3321 /// \param ExplicitTemplateArgs the explicit template arguments provided
3324 /// \param Args the function call arguments
3326 /// \param Specialization if template argument deduction was successful,
3327 /// this will be set to the function template specialization produced by
3328 /// template argument deduction.
3330 /// \param Info the argument will be updated to provide additional information
3331 /// about template argument deduction.
3333 /// \returns the result of template argument deduction.
3334 Sema::TemplateDeductionResult Sema::DeduceTemplateArguments(
3335 FunctionTemplateDecl *FunctionTemplate,
3336 TemplateArgumentListInfo *ExplicitTemplateArgs, ArrayRef<Expr *> Args,
3337 FunctionDecl *&Specialization, TemplateDeductionInfo &Info,
3338 bool PartialOverloading) {
3339 if (FunctionTemplate->isInvalidDecl())
3342 FunctionDecl *Function = FunctionTemplate->getTemplatedDecl();
3343 unsigned NumParams = Function->getNumParams();
3345 // C++ [temp.deduct.call]p1:
3346 // Template argument deduction is done by comparing each function template
3347 // parameter type (call it P) with the type of the corresponding argument
3348 // of the call (call it A) as described below.
3349 unsigned CheckArgs = Args.size();
3350 if (Args.size() < Function->getMinRequiredArguments() && !PartialOverloading)
3351 return TDK_TooFewArguments;
3352 else if (TooManyArguments(NumParams, Args.size(), PartialOverloading)) {
3353 const FunctionProtoType *Proto
3354 = Function->getType()->getAs<FunctionProtoType>();
3355 if (Proto->isTemplateVariadic())
3357 else if (Proto->isVariadic())
3358 CheckArgs = NumParams;
3360 return TDK_TooManyArguments;
3363 // The types of the parameters from which we will perform template argument
3365 LocalInstantiationScope InstScope(*this);
3366 TemplateParameterList *TemplateParams
3367 = FunctionTemplate->getTemplateParameters();
3368 SmallVector<DeducedTemplateArgument, 4> Deduced;
3369 SmallVector<QualType, 4> ParamTypes;
3370 unsigned NumExplicitlySpecified = 0;
3371 if (ExplicitTemplateArgs) {
3372 TemplateDeductionResult Result =
3373 SubstituteExplicitTemplateArguments(FunctionTemplate,
3374 *ExplicitTemplateArgs,
3382 NumExplicitlySpecified = Deduced.size();
3384 // Just fill in the parameter types from the function declaration.
3385 for (unsigned I = 0; I != NumParams; ++I)
3386 ParamTypes.push_back(Function->getParamDecl(I)->getType());
3389 // Deduce template arguments from the function parameters.
3390 Deduced.resize(TemplateParams->size());
3391 unsigned ArgIdx = 0;
3392 SmallVector<OriginalCallArg, 4> OriginalCallArgs;
3393 for (unsigned ParamIdx = 0, NumParamTypes = ParamTypes.size();
3394 ParamIdx != NumParamTypes; ++ParamIdx) {
3395 QualType OrigParamType = ParamTypes[ParamIdx];
3396 QualType ParamType = OrigParamType;
3398 const PackExpansionType *ParamExpansion
3399 = dyn_cast<PackExpansionType>(ParamType);
3400 if (!ParamExpansion) {
3401 // Simple case: matching a function parameter to a function argument.
3402 if (ArgIdx >= CheckArgs)
3405 Expr *Arg = Args[ArgIdx++];
3406 QualType ArgType = Arg->getType();
3409 if (AdjustFunctionParmAndArgTypesForDeduction(*this, TemplateParams,
3410 ParamType, ArgType, Arg,
3414 // If we have nothing to deduce, we're done.
3415 if (!hasDeducibleTemplateParameters(*this, FunctionTemplate, ParamType))
3418 // If the argument is an initializer list ...
3419 if (InitListExpr *ILE = dyn_cast<InitListExpr>(Arg)) {
3420 TemplateDeductionResult Result;
3421 // Removing references was already done.
3422 if (!DeduceFromInitializerList(*this, TemplateParams, ParamType, ILE,
3423 Info, Deduced, TDF, Result))
3428 // Don't track the argument type, since an initializer list has none.
3432 // Keep track of the argument type and corresponding parameter index,
3433 // so we can check for compatibility between the deduced A and A.
3434 OriginalCallArgs.push_back(OriginalCallArg(OrigParamType, ArgIdx-1,
3437 if (TemplateDeductionResult Result
3438 = DeduceTemplateArgumentsByTypeMatch(*this, TemplateParams,
3440 Info, Deduced, TDF))
3446 // C++0x [temp.deduct.call]p1:
3447 // For a function parameter pack that occurs at the end of the
3448 // parameter-declaration-list, the type A of each remaining argument of
3449 // the call is compared with the type P of the declarator-id of the
3450 // function parameter pack. Each comparison deduces template arguments
3451 // for subsequent positions in the template parameter packs expanded by
3452 // the function parameter pack. For a function parameter pack that does
3453 // not occur at the end of the parameter-declaration-list, the type of
3454 // the parameter pack is a non-deduced context.
3455 if (ParamIdx + 1 < NumParamTypes)
3458 QualType ParamPattern = ParamExpansion->getPattern();
3459 PackDeductionScope PackScope(*this, TemplateParams, Deduced, Info,
3462 bool HasAnyArguments = false;
3463 for (; ArgIdx < Args.size(); ++ArgIdx) {
3464 HasAnyArguments = true;
3466 QualType OrigParamType = ParamPattern;
3467 ParamType = OrigParamType;
3468 Expr *Arg = Args[ArgIdx];
3469 QualType ArgType = Arg->getType();
3472 if (AdjustFunctionParmAndArgTypesForDeduction(*this, TemplateParams,
3473 ParamType, ArgType, Arg,
3475 // We can't actually perform any deduction for this argument, so stop
3476 // deduction at this point.
3481 // As above, initializer lists need special handling.
3482 if (InitListExpr *ILE = dyn_cast<InitListExpr>(Arg)) {
3483 TemplateDeductionResult Result;
3484 if (!DeduceFromInitializerList(*this, TemplateParams, ParamType, ILE,
3485 Info, Deduced, TDF, Result)) {
3494 // Keep track of the argument type and corresponding argument index,
3495 // so we can check for compatibility between the deduced A and A.
3496 if (hasDeducibleTemplateParameters(*this, FunctionTemplate, ParamType))
3497 OriginalCallArgs.push_back(OriginalCallArg(OrigParamType, ArgIdx,
3500 if (TemplateDeductionResult Result
3501 = DeduceTemplateArgumentsByTypeMatch(*this, TemplateParams,
3502 ParamType, ArgType, Info,
3507 PackScope.nextPackElement();
3510 // Build argument packs for each of the parameter packs expanded by this
3512 if (auto Result = PackScope.finish(HasAnyArguments))
3515 // After we've matching against a parameter pack, we're done.
3519 return FinishTemplateArgumentDeduction(FunctionTemplate, Deduced,
3520 NumExplicitlySpecified, Specialization,
3521 Info, &OriginalCallArgs,
3522 PartialOverloading);
3525 QualType Sema::adjustCCAndNoReturn(QualType ArgFunctionType,
3526 QualType FunctionType) {
3527 if (ArgFunctionType.isNull())
3528 return ArgFunctionType;
3530 const FunctionProtoType *FunctionTypeP =
3531 FunctionType->castAs<FunctionProtoType>();
3532 CallingConv CC = FunctionTypeP->getCallConv();
3533 bool NoReturn = FunctionTypeP->getNoReturnAttr();
3534 const FunctionProtoType *ArgFunctionTypeP =
3535 ArgFunctionType->getAs<FunctionProtoType>();
3536 if (ArgFunctionTypeP->getCallConv() == CC &&
3537 ArgFunctionTypeP->getNoReturnAttr() == NoReturn)
3538 return ArgFunctionType;
3540 FunctionType::ExtInfo EI = ArgFunctionTypeP->getExtInfo().withCallingConv(CC);
3541 EI = EI.withNoReturn(NoReturn);
3543 cast<FunctionProtoType>(Context.adjustFunctionType(ArgFunctionTypeP, EI));
3544 return QualType(ArgFunctionTypeP, 0);
3547 /// \brief Deduce template arguments when taking the address of a function
3548 /// template (C++ [temp.deduct.funcaddr]) or matching a specialization to
3551 /// \param FunctionTemplate the function template for which we are performing
3552 /// template argument deduction.
3554 /// \param ExplicitTemplateArgs the explicitly-specified template
3557 /// \param ArgFunctionType the function type that will be used as the
3558 /// "argument" type (A) when performing template argument deduction from the
3559 /// function template's function type. This type may be NULL, if there is no
3560 /// argument type to compare against, in C++0x [temp.arg.explicit]p3.
3562 /// \param Specialization if template argument deduction was successful,
3563 /// this will be set to the function template specialization produced by
3564 /// template argument deduction.
3566 /// \param Info the argument will be updated to provide additional information
3567 /// about template argument deduction.
3569 /// \returns the result of template argument deduction.
3570 Sema::TemplateDeductionResult
3571 Sema::DeduceTemplateArguments(FunctionTemplateDecl *FunctionTemplate,
3572 TemplateArgumentListInfo *ExplicitTemplateArgs,
3573 QualType ArgFunctionType,
3574 FunctionDecl *&Specialization,
3575 TemplateDeductionInfo &Info,
3576 bool InOverloadResolution) {
3577 if (FunctionTemplate->isInvalidDecl())
3580 FunctionDecl *Function = FunctionTemplate->getTemplatedDecl();
3581 TemplateParameterList *TemplateParams
3582 = FunctionTemplate->getTemplateParameters();
3583 QualType FunctionType = Function->getType();
3584 if (!InOverloadResolution)
3585 ArgFunctionType = adjustCCAndNoReturn(ArgFunctionType, FunctionType);
3587 // Substitute any explicit template arguments.
3588 LocalInstantiationScope InstScope(*this);
3589 SmallVector<DeducedTemplateArgument, 4> Deduced;
3590 unsigned NumExplicitlySpecified = 0;
3591 SmallVector<QualType, 4> ParamTypes;
3592 if (ExplicitTemplateArgs) {
3593 if (TemplateDeductionResult Result
3594 = SubstituteExplicitTemplateArguments(FunctionTemplate,
3595 *ExplicitTemplateArgs,
3596 Deduced, ParamTypes,
3597 &FunctionType, Info))
3600 NumExplicitlySpecified = Deduced.size();
3603 // Unevaluated SFINAE context.
3604 EnterExpressionEvaluationContext Unevaluated(*this, Sema::Unevaluated);
3605 SFINAETrap Trap(*this);
3607 Deduced.resize(TemplateParams->size());
3609 // If the function has a deduced return type, substitute it for a dependent
3610 // type so that we treat it as a non-deduced context in what follows.
3611 bool HasDeducedReturnType = false;
3612 if (getLangOpts().CPlusPlus14 && InOverloadResolution &&
3613 Function->getReturnType()->getContainedAutoType()) {
3614 FunctionType = SubstAutoType(FunctionType, Context.DependentTy);
3615 HasDeducedReturnType = true;
3618 if (!ArgFunctionType.isNull()) {
3619 unsigned TDF = TDF_TopLevelParameterTypeList;
3620 if (InOverloadResolution) TDF |= TDF_InOverloadResolution;
3621 // Deduce template arguments from the function type.
3622 if (TemplateDeductionResult Result
3623 = DeduceTemplateArgumentsByTypeMatch(*this, TemplateParams,
3624 FunctionType, ArgFunctionType,
3625 Info, Deduced, TDF))
3629 if (TemplateDeductionResult Result
3630 = FinishTemplateArgumentDeduction(FunctionTemplate, Deduced,
3631 NumExplicitlySpecified,
3632 Specialization, Info))
3635 // If the function has a deduced return type, deduce it now, so we can check
3636 // that the deduced function type matches the requested type.
3637 if (HasDeducedReturnType &&
3638 Specialization->getReturnType()->isUndeducedType() &&
3639 DeduceReturnType(Specialization, Info.getLocation(), false))
3640 return TDK_MiscellaneousDeductionFailure;
3642 // If the requested function type does not match the actual type of the
3643 // specialization with respect to arguments of compatible pointer to function
3644 // types, template argument deduction fails.
3645 if (!ArgFunctionType.isNull()) {
3646 if (InOverloadResolution && !isSameOrCompatibleFunctionType(
3647 Context.getCanonicalType(Specialization->getType()),
3648 Context.getCanonicalType(ArgFunctionType)))
3649 return TDK_MiscellaneousDeductionFailure;
3650 else if(!InOverloadResolution &&
3651 !Context.hasSameType(Specialization->getType(), ArgFunctionType))
3652 return TDK_MiscellaneousDeductionFailure;
3658 /// \brief Given a function declaration (e.g. a generic lambda conversion
3659 /// function) that contains an 'auto' in its result type, substitute it
3660 /// with TypeToReplaceAutoWith. Be careful to pass in the type you want
3661 /// to replace 'auto' with and not the actual result type you want
3662 /// to set the function to.
3664 SubstAutoWithinFunctionReturnType(FunctionDecl *F,
3665 QualType TypeToReplaceAutoWith, Sema &S) {
3666 assert(!TypeToReplaceAutoWith->getContainedAutoType());
3667 QualType AutoResultType = F->getReturnType();
3668 assert(AutoResultType->getContainedAutoType());
3669 QualType DeducedResultType = S.SubstAutoType(AutoResultType,
3670 TypeToReplaceAutoWith);
3671 S.Context.adjustDeducedFunctionResultType(F, DeducedResultType);
3674 /// \brief Given a specialized conversion operator of a generic lambda
3675 /// create the corresponding specializations of the call operator and
3676 /// the static-invoker. If the return type of the call operator is auto,
3677 /// deduce its return type and check if that matches the
3678 /// return type of the destination function ptr.
3680 static inline Sema::TemplateDeductionResult
3681 SpecializeCorrespondingLambdaCallOperatorAndInvoker(
3682 CXXConversionDecl *ConversionSpecialized,
3683 SmallVectorImpl<DeducedTemplateArgument> &DeducedArguments,
3684 QualType ReturnTypeOfDestFunctionPtr,
3685 TemplateDeductionInfo &TDInfo,
3688 CXXRecordDecl *LambdaClass = ConversionSpecialized->getParent();
3689 assert(LambdaClass && LambdaClass->isGenericLambda());
3691 CXXMethodDecl *CallOpGeneric = LambdaClass->getLambdaCallOperator();
3692 QualType CallOpResultType = CallOpGeneric->getReturnType();
3693 const bool GenericLambdaCallOperatorHasDeducedReturnType =
3694 CallOpResultType->getContainedAutoType();
3696 FunctionTemplateDecl *CallOpTemplate =
3697 CallOpGeneric->getDescribedFunctionTemplate();
3699 FunctionDecl *CallOpSpecialized = nullptr;
3700 // Use the deduced arguments of the conversion function, to specialize our
3701 // generic lambda's call operator.
3702 if (Sema::TemplateDeductionResult Result
3703 = S.FinishTemplateArgumentDeduction(CallOpTemplate,
3705 0, CallOpSpecialized, TDInfo))
3708 // If we need to deduce the return type, do so (instantiates the callop).
3709 if (GenericLambdaCallOperatorHasDeducedReturnType &&
3710 CallOpSpecialized->getReturnType()->isUndeducedType())
3711 S.DeduceReturnType(CallOpSpecialized,
3712 CallOpSpecialized->getPointOfInstantiation(),
3715 // Check to see if the return type of the destination ptr-to-function
3716 // matches the return type of the call operator.
3717 if (!S.Context.hasSameType(CallOpSpecialized->getReturnType(),
3718 ReturnTypeOfDestFunctionPtr))
3719 return Sema::TDK_NonDeducedMismatch;
3720 // Since we have succeeded in matching the source and destination
3721 // ptr-to-functions (now including return type), and have successfully
3722 // specialized our corresponding call operator, we are ready to
3723 // specialize the static invoker with the deduced arguments of our
3725 FunctionDecl *InvokerSpecialized = nullptr;
3726 FunctionTemplateDecl *InvokerTemplate = LambdaClass->
3727 getLambdaStaticInvoker()->getDescribedFunctionTemplate();
3730 Sema::TemplateDeductionResult LLVM_ATTRIBUTE_UNUSED Result =
3732 S.FinishTemplateArgumentDeduction(InvokerTemplate, DeducedArguments, 0,
3733 InvokerSpecialized, TDInfo);
3734 assert(Result == Sema::TDK_Success &&
3735 "If the call operator succeeded so should the invoker!");
3736 // Set the result type to match the corresponding call operator
3737 // specialization's result type.
3738 if (GenericLambdaCallOperatorHasDeducedReturnType &&
3739 InvokerSpecialized->getReturnType()->isUndeducedType()) {
3740 // Be sure to get the type to replace 'auto' with and not
3741 // the full result type of the call op specialization
3742 // to substitute into the 'auto' of the invoker and conversion
3745 // int* (*fp)(int*) = [](auto* a) -> auto* { return a; };
3746 // We don't want to subst 'int*' into 'auto' to get int**.
3748 QualType TypeToReplaceAutoWith = CallOpSpecialized->getReturnType()
3749 ->getContainedAutoType()
3751 SubstAutoWithinFunctionReturnType(InvokerSpecialized,
3752 TypeToReplaceAutoWith, S);
3753 SubstAutoWithinFunctionReturnType(ConversionSpecialized,
3754 TypeToReplaceAutoWith, S);
3757 // Ensure that static invoker doesn't have a const qualifier.
3758 // FIXME: When creating the InvokerTemplate in SemaLambda.cpp
3759 // do not use the CallOperator's TypeSourceInfo which allows
3760 // the const qualifier to leak through.
3761 const FunctionProtoType *InvokerFPT = InvokerSpecialized->
3762 getType().getTypePtr()->castAs<FunctionProtoType>();
3763 FunctionProtoType::ExtProtoInfo EPI = InvokerFPT->getExtProtoInfo();
3765 InvokerSpecialized->setType(S.Context.getFunctionType(
3766 InvokerFPT->getReturnType(), InvokerFPT->getParamTypes(), EPI));
3767 return Sema::TDK_Success;
3769 /// \brief Deduce template arguments for a templated conversion
3770 /// function (C++ [temp.deduct.conv]) and, if successful, produce a
3771 /// conversion function template specialization.
3772 Sema::TemplateDeductionResult
3773 Sema::DeduceTemplateArguments(FunctionTemplateDecl *ConversionTemplate,
3775 CXXConversionDecl *&Specialization,
3776 TemplateDeductionInfo &Info) {
3777 if (ConversionTemplate->isInvalidDecl())
3780 CXXConversionDecl *ConversionGeneric
3781 = cast<CXXConversionDecl>(ConversionTemplate->getTemplatedDecl());
3783 QualType FromType = ConversionGeneric->getConversionType();
3785 // Canonicalize the types for deduction.
3786 QualType P = Context.getCanonicalType(FromType);
3787 QualType A = Context.getCanonicalType(ToType);
3789 // C++0x [temp.deduct.conv]p2:
3790 // If P is a reference type, the type referred to by P is used for
3792 if (const ReferenceType *PRef = P->getAs<ReferenceType>())
3793 P = PRef->getPointeeType();
3795 // C++0x [temp.deduct.conv]p4:
3796 // [...] If A is a reference type, the type referred to by A is used
3797 // for type deduction.
3798 if (const ReferenceType *ARef = A->getAs<ReferenceType>())
3799 A = ARef->getPointeeType().getUnqualifiedType();
3800 // C++ [temp.deduct.conv]p3:
3802 // If A is not a reference type:
3804 assert(!A->isReferenceType() && "Reference types were handled above");
3806 // - If P is an array type, the pointer type produced by the
3807 // array-to-pointer standard conversion (4.2) is used in place
3808 // of P for type deduction; otherwise,
3809 if (P->isArrayType())
3810 P = Context.getArrayDecayedType(P);
3811 // - If P is a function type, the pointer type produced by the
3812 // function-to-pointer standard conversion (4.3) is used in
3813 // place of P for type deduction; otherwise,
3814 else if (P->isFunctionType())
3815 P = Context.getPointerType(P);
3816 // - If P is a cv-qualified type, the top level cv-qualifiers of
3817 // P's type are ignored for type deduction.
3819 P = P.getUnqualifiedType();
3821 // C++0x [temp.deduct.conv]p4:
3822 // If A is a cv-qualified type, the top level cv-qualifiers of A's
3823 // type are ignored for type deduction. If A is a reference type, the type
3824 // referred to by A is used for type deduction.
3825 A = A.getUnqualifiedType();
3828 // Unevaluated SFINAE context.
3829 EnterExpressionEvaluationContext Unevaluated(*this, Sema::Unevaluated);
3830 SFINAETrap Trap(*this);
3832 // C++ [temp.deduct.conv]p1:
3833 // Template argument deduction is done by comparing the return
3834 // type of the template conversion function (call it P) with the
3835 // type that is required as the result of the conversion (call it
3836 // A) as described in 14.8.2.4.
3837 TemplateParameterList *TemplateParams
3838 = ConversionTemplate->getTemplateParameters();
3839 SmallVector<DeducedTemplateArgument, 4> Deduced;
3840 Deduced.resize(TemplateParams->size());
3842 // C++0x [temp.deduct.conv]p4:
3843 // In general, the deduction process attempts to find template
3844 // argument values that will make the deduced A identical to
3845 // A. However, there are two cases that allow a difference:
3847 // - If the original A is a reference type, A can be more
3848 // cv-qualified than the deduced A (i.e., the type referred to
3849 // by the reference)
3850 if (ToType->isReferenceType())
3851 TDF |= TDF_ParamWithReferenceType;
3852 // - The deduced A can be another pointer or pointer to member
3853 // type that can be converted to A via a qualification
3856 // (C++0x [temp.deduct.conv]p6 clarifies that this only happens when
3857 // both P and A are pointers or member pointers. In this case, we
3858 // just ignore cv-qualifiers completely).
3859 if ((P->isPointerType() && A->isPointerType()) ||
3860 (P->isMemberPointerType() && A->isMemberPointerType()))
3861 TDF |= TDF_IgnoreQualifiers;
3862 if (TemplateDeductionResult Result
3863 = DeduceTemplateArgumentsByTypeMatch(*this, TemplateParams,
3864 P, A, Info, Deduced, TDF))
3867 // Create an Instantiation Scope for finalizing the operator.
3868 LocalInstantiationScope InstScope(*this);
3869 // Finish template argument deduction.
3870 FunctionDecl *ConversionSpecialized = nullptr;
3871 TemplateDeductionResult Result
3872 = FinishTemplateArgumentDeduction(ConversionTemplate, Deduced, 0,
3873 ConversionSpecialized, Info);
3874 Specialization = cast_or_null<CXXConversionDecl>(ConversionSpecialized);
3876 // If the conversion operator is being invoked on a lambda closure to convert
3877 // to a ptr-to-function, use the deduced arguments from the conversion
3878 // function to specialize the corresponding call operator.
3879 // e.g., int (*fp)(int) = [](auto a) { return a; };
3880 if (Result == TDK_Success && isLambdaConversionOperator(ConversionGeneric)) {
3882 // Get the return type of the destination ptr-to-function we are converting
3883 // to. This is necessary for matching the lambda call operator's return
3884 // type to that of the destination ptr-to-function's return type.
3885 assert(A->isPointerType() &&
3886 "Can only convert from lambda to ptr-to-function");
3887 const FunctionType *ToFunType =
3888 A->getPointeeType().getTypePtr()->getAs<FunctionType>();
3889 const QualType DestFunctionPtrReturnType = ToFunType->getReturnType();
3891 // Create the corresponding specializations of the call operator and
3892 // the static-invoker; and if the return type is auto,
3893 // deduce the return type and check if it matches the
3894 // DestFunctionPtrReturnType.
3896 // auto L = [](auto a) { return f(a); };
3897 // int (*fp)(int) = L;
3898 // char (*fp2)(int) = L; <-- Not OK.
3900 Result = SpecializeCorrespondingLambdaCallOperatorAndInvoker(
3901 Specialization, Deduced, DestFunctionPtrReturnType,
3907 /// \brief Deduce template arguments for a function template when there is
3908 /// nothing to deduce against (C++0x [temp.arg.explicit]p3).
3910 /// \param FunctionTemplate the function template for which we are performing
3911 /// template argument deduction.
3913 /// \param ExplicitTemplateArgs the explicitly-specified template
3916 /// \param Specialization if template argument deduction was successful,
3917 /// this will be set to the function template specialization produced by
3918 /// template argument deduction.
3920 /// \param Info the argument will be updated to provide additional information
3921 /// about template argument deduction.
3923 /// \returns the result of template argument deduction.
3924 Sema::TemplateDeductionResult
3925 Sema::DeduceTemplateArguments(FunctionTemplateDecl *FunctionTemplate,
3926 TemplateArgumentListInfo *ExplicitTemplateArgs,
3927 FunctionDecl *&Specialization,
3928 TemplateDeductionInfo &Info,
3929 bool InOverloadResolution) {
3930 return DeduceTemplateArguments(FunctionTemplate, ExplicitTemplateArgs,
3931 QualType(), Specialization, Info,
3932 InOverloadResolution);
3936 /// Substitute the 'auto' type specifier within a type for a given replacement
3938 class SubstituteAutoTransform :
3939 public TreeTransform<SubstituteAutoTransform> {
3940 QualType Replacement;
3942 SubstituteAutoTransform(Sema &SemaRef, QualType Replacement)
3943 : TreeTransform<SubstituteAutoTransform>(SemaRef),
3944 Replacement(Replacement) {}
3946 QualType TransformAutoType(TypeLocBuilder &TLB, AutoTypeLoc TL) {
3947 // If we're building the type pattern to deduce against, don't wrap the
3948 // substituted type in an AutoType. Certain template deduction rules
3949 // apply only when a template type parameter appears directly (and not if
3950 // the parameter is found through desugaring). For instance:
3951 // auto &&lref = lvalue;
3952 // must transform into "rvalue reference to T" not "rvalue reference to
3953 // auto type deduced as T" in order for [temp.deduct.call]p3 to apply.
3954 if (!Replacement.isNull() && isa<TemplateTypeParmType>(Replacement)) {
3955 QualType Result = Replacement;
3956 TemplateTypeParmTypeLoc NewTL =
3957 TLB.push<TemplateTypeParmTypeLoc>(Result);
3958 NewTL.setNameLoc(TL.getNameLoc());
3962 !Replacement.isNull() && Replacement->isDependentType();
3964 SemaRef.Context.getAutoType(Dependent ? QualType() : Replacement,
3965 TL.getTypePtr()->getKeyword(),
3967 AutoTypeLoc NewTL = TLB.push<AutoTypeLoc>(Result);
3968 NewTL.setNameLoc(TL.getNameLoc());
3973 ExprResult TransformLambdaExpr(LambdaExpr *E) {
3974 // Lambdas never need to be transformed.
3978 QualType Apply(TypeLoc TL) {
3979 // Create some scratch storage for the transformed type locations.
3980 // FIXME: We're just going to throw this information away. Don't build it.
3982 TLB.reserve(TL.getFullDataSize());
3983 return TransformType(TLB, TL);
3988 Sema::DeduceAutoResult
3989 Sema::DeduceAutoType(TypeSourceInfo *Type, Expr *&Init, QualType &Result) {
3990 return DeduceAutoType(Type->getTypeLoc(), Init, Result);
3993 /// \brief Deduce the type for an auto type-specifier (C++11 [dcl.spec.auto]p6)
3995 /// \param Type the type pattern using the auto type-specifier.
3996 /// \param Init the initializer for the variable whose type is to be deduced.
3997 /// \param Result if type deduction was successful, this will be set to the
3999 Sema::DeduceAutoResult
4000 Sema::DeduceAutoType(TypeLoc Type, Expr *&Init, QualType &Result) {
4001 if (Init->getType()->isNonOverloadPlaceholderType()) {
4002 ExprResult NonPlaceholder = CheckPlaceholderExpr(Init);
4003 if (NonPlaceholder.isInvalid())
4004 return DAR_FailedAlreadyDiagnosed;
4005 Init = NonPlaceholder.get();
4008 if (Init->isTypeDependent() || Type.getType()->isDependentType()) {
4009 Result = SubstituteAutoTransform(*this, Context.DependentTy).Apply(Type);
4010 assert(!Result.isNull() && "substituting DependentTy can't fail");
4011 return DAR_Succeeded;
4014 // If this is a 'decltype(auto)' specifier, do the decltype dance.
4015 // Since 'decltype(auto)' can only occur at the top of the type, we
4016 // don't need to go digging for it.
4017 if (const AutoType *AT = Type.getType()->getAs<AutoType>()) {
4018 if (AT->isDecltypeAuto()) {
4019 if (isa<InitListExpr>(Init)) {
4020 Diag(Init->getLocStart(), diag::err_decltype_auto_initializer_list);
4021 return DAR_FailedAlreadyDiagnosed;
4024 QualType Deduced = BuildDecltypeType(Init, Init->getLocStart(), false);
4025 if (Deduced.isNull())
4026 return DAR_FailedAlreadyDiagnosed;
4027 // FIXME: Support a non-canonical deduced type for 'auto'.
4028 Deduced = Context.getCanonicalType(Deduced);
4029 Result = SubstituteAutoTransform(*this, Deduced).Apply(Type);
4030 if (Result.isNull())
4031 return DAR_FailedAlreadyDiagnosed;
4032 return DAR_Succeeded;
4033 } else if (!getLangOpts().CPlusPlus) {
4034 if (isa<InitListExpr>(Init)) {
4035 Diag(Init->getLocStart(), diag::err_auto_init_list_from_c);
4036 return DAR_FailedAlreadyDiagnosed;
4041 SourceLocation Loc = Init->getExprLoc();
4043 LocalInstantiationScope InstScope(*this);
4045 // Build template<class TemplParam> void Func(FuncParam);
4046 TemplateTypeParmDecl *TemplParam =
4047 TemplateTypeParmDecl::Create(Context, nullptr, SourceLocation(), Loc, 0, 0,
4048 nullptr, false, false);
4049 QualType TemplArg = QualType(TemplParam->getTypeForDecl(), 0);
4050 NamedDecl *TemplParamPtr = TemplParam;
4051 FixedSizeTemplateParameterListStorage<1> TemplateParamsSt(
4052 Loc, Loc, TemplParamPtr, Loc);
4054 QualType FuncParam = SubstituteAutoTransform(*this, TemplArg).Apply(Type);
4055 assert(!FuncParam.isNull() &&
4056 "substituting template parameter for 'auto' failed");
4058 // Deduce type of TemplParam in Func(Init)
4059 SmallVector<DeducedTemplateArgument, 1> Deduced;
4061 QualType InitType = Init->getType();
4064 TemplateDeductionInfo Info(Loc);
4066 InitListExpr *InitList = dyn_cast<InitListExpr>(Init);
4068 for (unsigned i = 0, e = InitList->getNumInits(); i < e; ++i) {
4069 if (DeduceTemplateArgumentByListElement(*this, TemplateParamsSt.get(),
4070 TemplArg, InitList->getInit(i),
4071 Info, Deduced, TDF))
4075 if (!getLangOpts().CPlusPlus && Init->refersToBitField()) {
4076 Diag(Loc, diag::err_auto_bitfield);
4077 return DAR_FailedAlreadyDiagnosed;
4080 if (AdjustFunctionParmAndArgTypesForDeduction(
4081 *this, TemplateParamsSt.get(), FuncParam, InitType, Init, TDF))
4084 if (DeduceTemplateArgumentsByTypeMatch(*this, TemplateParamsSt.get(),
4085 FuncParam, InitType, Info, Deduced,
4090 if (Deduced[0].getKind() != TemplateArgument::Type)
4093 QualType DeducedType = Deduced[0].getAsType();
4096 DeducedType = BuildStdInitializerList(DeducedType, Loc);
4097 if (DeducedType.isNull())
4098 return DAR_FailedAlreadyDiagnosed;
4101 Result = SubstituteAutoTransform(*this, DeducedType).Apply(Type);
4102 if (Result.isNull())
4103 return DAR_FailedAlreadyDiagnosed;
4105 // Check that the deduced argument type is compatible with the original
4106 // argument type per C++ [temp.deduct.call]p4.
4107 if (!InitList && !Result.isNull() &&
4108 CheckOriginalCallArgDeduction(*this,
4109 Sema::OriginalCallArg(FuncParam,0,InitType),
4111 Result = QualType();
4115 return DAR_Succeeded;
4118 QualType Sema::SubstAutoType(QualType TypeWithAuto,
4119 QualType TypeToReplaceAuto) {
4120 return SubstituteAutoTransform(*this, TypeToReplaceAuto).
4121 TransformType(TypeWithAuto);
4124 TypeSourceInfo* Sema::SubstAutoTypeSourceInfo(TypeSourceInfo *TypeWithAuto,
4125 QualType TypeToReplaceAuto) {
4126 return SubstituteAutoTransform(*this, TypeToReplaceAuto).
4127 TransformType(TypeWithAuto);
4130 void Sema::DiagnoseAutoDeductionFailure(VarDecl *VDecl, Expr *Init) {
4131 if (isa<InitListExpr>(Init))
4132 Diag(VDecl->getLocation(),
4133 VDecl->isInitCapture()
4134 ? diag::err_init_capture_deduction_failure_from_init_list
4135 : diag::err_auto_var_deduction_failure_from_init_list)
4136 << VDecl->getDeclName() << VDecl->getType() << Init->getSourceRange();
4138 Diag(VDecl->getLocation(),
4139 VDecl->isInitCapture() ? diag::err_init_capture_deduction_failure
4140 : diag::err_auto_var_deduction_failure)
4141 << VDecl->getDeclName() << VDecl->getType() << Init->getType()
4142 << Init->getSourceRange();
4145 bool Sema::DeduceReturnType(FunctionDecl *FD, SourceLocation Loc,
4147 assert(FD->getReturnType()->isUndeducedType());
4149 if (FD->getTemplateInstantiationPattern())
4150 InstantiateFunctionDefinition(Loc, FD);
4152 bool StillUndeduced = FD->getReturnType()->isUndeducedType();
4153 if (StillUndeduced && Diagnose && !FD->isInvalidDecl()) {
4154 Diag(Loc, diag::err_auto_fn_used_before_defined) << FD;
4155 Diag(FD->getLocation(), diag::note_callee_decl) << FD;
4158 return StillUndeduced;
4162 MarkUsedTemplateParameters(ASTContext &Ctx, QualType T,
4165 llvm::SmallBitVector &Deduced);
4167 /// \brief If this is a non-static member function,
4169 AddImplicitObjectParameterType(ASTContext &Context,
4170 CXXMethodDecl *Method,
4171 SmallVectorImpl<QualType> &ArgTypes) {
4172 // C++11 [temp.func.order]p3:
4173 // [...] The new parameter is of type "reference to cv A," where cv are
4174 // the cv-qualifiers of the function template (if any) and A is
4175 // the class of which the function template is a member.
4177 // The standard doesn't say explicitly, but we pick the appropriate kind of
4178 // reference type based on [over.match.funcs]p4.
4179 QualType ArgTy = Context.getTypeDeclType(Method->getParent());
4180 ArgTy = Context.getQualifiedType(ArgTy,
4181 Qualifiers::fromCVRMask(Method->getTypeQualifiers()));
4182 if (Method->getRefQualifier() == RQ_RValue)
4183 ArgTy = Context.getRValueReferenceType(ArgTy);
4185 ArgTy = Context.getLValueReferenceType(ArgTy);
4186 ArgTypes.push_back(ArgTy);
4189 /// \brief Determine whether the function template \p FT1 is at least as
4190 /// specialized as \p FT2.
4191 static bool isAtLeastAsSpecializedAs(Sema &S,
4193 FunctionTemplateDecl *FT1,
4194 FunctionTemplateDecl *FT2,
4195 TemplatePartialOrderingContext TPOC,
4196 unsigned NumCallArguments1) {
4197 FunctionDecl *FD1 = FT1->getTemplatedDecl();
4198 FunctionDecl *FD2 = FT2->getTemplatedDecl();
4199 const FunctionProtoType *Proto1 = FD1->getType()->getAs<FunctionProtoType>();
4200 const FunctionProtoType *Proto2 = FD2->getType()->getAs<FunctionProtoType>();
4202 assert(Proto1 && Proto2 && "Function templates must have prototypes");
4203 TemplateParameterList *TemplateParams = FT2->getTemplateParameters();
4204 SmallVector<DeducedTemplateArgument, 4> Deduced;
4205 Deduced.resize(TemplateParams->size());
4207 // C++0x [temp.deduct.partial]p3:
4208 // The types used to determine the ordering depend on the context in which
4209 // the partial ordering is done:
4210 TemplateDeductionInfo Info(Loc);
4211 SmallVector<QualType, 4> Args2;
4214 // - In the context of a function call, the function parameter types are
4216 CXXMethodDecl *Method1 = dyn_cast<CXXMethodDecl>(FD1);
4217 CXXMethodDecl *Method2 = dyn_cast<CXXMethodDecl>(FD2);
4219 // C++11 [temp.func.order]p3:
4220 // [...] If only one of the function templates is a non-static
4221 // member, that function template is considered to have a new
4222 // first parameter inserted in its function parameter list. The
4223 // new parameter is of type "reference to cv A," where cv are
4224 // the cv-qualifiers of the function template (if any) and A is
4225 // the class of which the function template is a member.
4227 // Note that we interpret this to mean "if one of the function
4228 // templates is a non-static member and the other is a non-member";
4229 // otherwise, the ordering rules for static functions against non-static
4230 // functions don't make any sense.
4232 // C++98/03 doesn't have this provision but we've extended DR532 to cover
4233 // it as wording was broken prior to it.
4234 SmallVector<QualType, 4> Args1;
4236 unsigned NumComparedArguments = NumCallArguments1;
4238 if (!Method2 && Method1 && !Method1->isStatic()) {
4239 // Compare 'this' from Method1 against first parameter from Method2.
4240 AddImplicitObjectParameterType(S.Context, Method1, Args1);
4241 ++NumComparedArguments;
4242 } else if (!Method1 && Method2 && !Method2->isStatic()) {
4243 // Compare 'this' from Method2 against first parameter from Method1.
4244 AddImplicitObjectParameterType(S.Context, Method2, Args2);
4247 Args1.insert(Args1.end(), Proto1->param_type_begin(),
4248 Proto1->param_type_end());
4249 Args2.insert(Args2.end(), Proto2->param_type_begin(),
4250 Proto2->param_type_end());
4252 // C++ [temp.func.order]p5:
4253 // The presence of unused ellipsis and default arguments has no effect on
4254 // the partial ordering of function templates.
4255 if (Args1.size() > NumComparedArguments)
4256 Args1.resize(NumComparedArguments);
4257 if (Args2.size() > NumComparedArguments)
4258 Args2.resize(NumComparedArguments);
4259 if (DeduceTemplateArguments(S, TemplateParams, Args2.data(), Args2.size(),
4260 Args1.data(), Args1.size(), Info, Deduced,
4261 TDF_None, /*PartialOrdering=*/true))
4267 case TPOC_Conversion:
4268 // - In the context of a call to a conversion operator, the return types
4269 // of the conversion function templates are used.
4270 if (DeduceTemplateArgumentsByTypeMatch(
4271 S, TemplateParams, Proto2->getReturnType(), Proto1->getReturnType(),
4272 Info, Deduced, TDF_None,
4273 /*PartialOrdering=*/true))
4278 // - In other contexts (14.6.6.2) the function template's function type
4280 if (DeduceTemplateArgumentsByTypeMatch(S, TemplateParams,
4281 FD2->getType(), FD1->getType(),
4282 Info, Deduced, TDF_None,
4283 /*PartialOrdering=*/true))
4288 // C++0x [temp.deduct.partial]p11:
4289 // In most cases, all template parameters must have values in order for
4290 // deduction to succeed, but for partial ordering purposes a template
4291 // parameter may remain without a value provided it is not used in the
4292 // types being used for partial ordering. [ Note: a template parameter used
4293 // in a non-deduced context is considered used. -end note]
4294 unsigned ArgIdx = 0, NumArgs = Deduced.size();
4295 for (; ArgIdx != NumArgs; ++ArgIdx)
4296 if (Deduced[ArgIdx].isNull())
4299 if (ArgIdx == NumArgs) {
4300 // All template arguments were deduced. FT1 is at least as specialized
4305 // Figure out which template parameters were used.
4306 llvm::SmallBitVector UsedParameters(TemplateParams->size());
4309 for (unsigned I = 0, N = Args2.size(); I != N; ++I)
4310 ::MarkUsedTemplateParameters(S.Context, Args2[I], false,
4311 TemplateParams->getDepth(),
4315 case TPOC_Conversion:
4316 ::MarkUsedTemplateParameters(S.Context, Proto2->getReturnType(), false,
4317 TemplateParams->getDepth(), UsedParameters);
4321 ::MarkUsedTemplateParameters(S.Context, FD2->getType(), false,
4322 TemplateParams->getDepth(),
4327 for (; ArgIdx != NumArgs; ++ArgIdx)
4328 // If this argument had no value deduced but was used in one of the types
4329 // used for partial ordering, then deduction fails.
4330 if (Deduced[ArgIdx].isNull() && UsedParameters[ArgIdx])
4336 /// \brief Determine whether this a function template whose parameter-type-list
4337 /// ends with a function parameter pack.
4338 static bool isVariadicFunctionTemplate(FunctionTemplateDecl *FunTmpl) {
4339 FunctionDecl *Function = FunTmpl->getTemplatedDecl();
4340 unsigned NumParams = Function->getNumParams();
4344 ParmVarDecl *Last = Function->getParamDecl(NumParams - 1);
4345 if (!Last->isParameterPack())
4348 // Make sure that no previous parameter is a parameter pack.
4349 while (--NumParams > 0) {
4350 if (Function->getParamDecl(NumParams - 1)->isParameterPack())
4357 /// \brief Returns the more specialized function template according
4358 /// to the rules of function template partial ordering (C++ [temp.func.order]).
4360 /// \param FT1 the first function template
4362 /// \param FT2 the second function template
4364 /// \param TPOC the context in which we are performing partial ordering of
4365 /// function templates.
4367 /// \param NumCallArguments1 The number of arguments in the call to FT1, used
4368 /// only when \c TPOC is \c TPOC_Call.
4370 /// \param NumCallArguments2 The number of arguments in the call to FT2, used
4371 /// only when \c TPOC is \c TPOC_Call.
4373 /// \returns the more specialized function template. If neither
4374 /// template is more specialized, returns NULL.
4375 FunctionTemplateDecl *
4376 Sema::getMoreSpecializedTemplate(FunctionTemplateDecl *FT1,
4377 FunctionTemplateDecl *FT2,
4379 TemplatePartialOrderingContext TPOC,
4380 unsigned NumCallArguments1,
4381 unsigned NumCallArguments2) {
4382 bool Better1 = isAtLeastAsSpecializedAs(*this, Loc, FT1, FT2, TPOC,
4384 bool Better2 = isAtLeastAsSpecializedAs(*this, Loc, FT2, FT1, TPOC,
4387 if (Better1 != Better2) // We have a clear winner
4388 return Better1 ? FT1 : FT2;
4390 if (!Better1 && !Better2) // Neither is better than the other
4393 // FIXME: This mimics what GCC implements, but doesn't match up with the
4394 // proposed resolution for core issue 692. This area needs to be sorted out,
4395 // but for now we attempt to maintain compatibility.
4396 bool Variadic1 = isVariadicFunctionTemplate(FT1);
4397 bool Variadic2 = isVariadicFunctionTemplate(FT2);
4398 if (Variadic1 != Variadic2)
4399 return Variadic1? FT2 : FT1;
4404 /// \brief Determine if the two templates are equivalent.
4405 static bool isSameTemplate(TemplateDecl *T1, TemplateDecl *T2) {
4412 return T1->getCanonicalDecl() == T2->getCanonicalDecl();
4415 /// \brief Retrieve the most specialized of the given function template
4416 /// specializations.
4418 /// \param SpecBegin the start iterator of the function template
4419 /// specializations that we will be comparing.
4421 /// \param SpecEnd the end iterator of the function template
4422 /// specializations, paired with \p SpecBegin.
4424 /// \param Loc the location where the ambiguity or no-specializations
4425 /// diagnostic should occur.
4427 /// \param NoneDiag partial diagnostic used to diagnose cases where there are
4428 /// no matching candidates.
4430 /// \param AmbigDiag partial diagnostic used to diagnose an ambiguity, if one
4433 /// \param CandidateDiag partial diagnostic used for each function template
4434 /// specialization that is a candidate in the ambiguous ordering. One parameter
4435 /// in this diagnostic should be unbound, which will correspond to the string
4436 /// describing the template arguments for the function template specialization.
4438 /// \returns the most specialized function template specialization, if
4439 /// found. Otherwise, returns SpecEnd.
4440 UnresolvedSetIterator Sema::getMostSpecialized(
4441 UnresolvedSetIterator SpecBegin, UnresolvedSetIterator SpecEnd,
4442 TemplateSpecCandidateSet &FailedCandidates,
4443 SourceLocation Loc, const PartialDiagnostic &NoneDiag,
4444 const PartialDiagnostic &AmbigDiag, const PartialDiagnostic &CandidateDiag,
4445 bool Complain, QualType TargetType) {
4446 if (SpecBegin == SpecEnd) {
4448 Diag(Loc, NoneDiag);
4449 FailedCandidates.NoteCandidates(*this, Loc);
4454 if (SpecBegin + 1 == SpecEnd)
4457 // Find the function template that is better than all of the templates it
4458 // has been compared to.
4459 UnresolvedSetIterator Best = SpecBegin;
4460 FunctionTemplateDecl *BestTemplate
4461 = cast<FunctionDecl>(*Best)->getPrimaryTemplate();
4462 assert(BestTemplate && "Not a function template specialization?");
4463 for (UnresolvedSetIterator I = SpecBegin + 1; I != SpecEnd; ++I) {
4464 FunctionTemplateDecl *Challenger
4465 = cast<FunctionDecl>(*I)->getPrimaryTemplate();
4466 assert(Challenger && "Not a function template specialization?");
4467 if (isSameTemplate(getMoreSpecializedTemplate(BestTemplate, Challenger,
4468 Loc, TPOC_Other, 0, 0),
4471 BestTemplate = Challenger;
4475 // Make sure that the "best" function template is more specialized than all
4477 bool Ambiguous = false;
4478 for (UnresolvedSetIterator I = SpecBegin; I != SpecEnd; ++I) {
4479 FunctionTemplateDecl *Challenger
4480 = cast<FunctionDecl>(*I)->getPrimaryTemplate();
4482 !isSameTemplate(getMoreSpecializedTemplate(BestTemplate, Challenger,
4483 Loc, TPOC_Other, 0, 0),
4491 // We found an answer. Return it.
4495 // Diagnose the ambiguity.
4497 Diag(Loc, AmbigDiag);
4499 // FIXME: Can we order the candidates in some sane way?
4500 for (UnresolvedSetIterator I = SpecBegin; I != SpecEnd; ++I) {
4501 PartialDiagnostic PD = CandidateDiag;
4502 PD << getTemplateArgumentBindingsText(
4503 cast<FunctionDecl>(*I)->getPrimaryTemplate()->getTemplateParameters(),
4504 *cast<FunctionDecl>(*I)->getTemplateSpecializationArgs());
4505 if (!TargetType.isNull())
4506 HandleFunctionTypeMismatch(PD, cast<FunctionDecl>(*I)->getType(),
4508 Diag((*I)->getLocation(), PD);
4515 /// \brief Returns the more specialized class template partial specialization
4516 /// according to the rules of partial ordering of class template partial
4517 /// specializations (C++ [temp.class.order]).
4519 /// \param PS1 the first class template partial specialization
4521 /// \param PS2 the second class template partial specialization
4523 /// \returns the more specialized class template partial specialization. If
4524 /// neither partial specialization is more specialized, returns NULL.
4525 ClassTemplatePartialSpecializationDecl *
4526 Sema::getMoreSpecializedPartialSpecialization(
4527 ClassTemplatePartialSpecializationDecl *PS1,
4528 ClassTemplatePartialSpecializationDecl *PS2,
4529 SourceLocation Loc) {
4530 // C++ [temp.class.order]p1:
4531 // For two class template partial specializations, the first is at least as
4532 // specialized as the second if, given the following rewrite to two
4533 // function templates, the first function template is at least as
4534 // specialized as the second according to the ordering rules for function
4535 // templates (14.6.6.2):
4536 // - the first function template has the same template parameters as the
4537 // first partial specialization and has a single function parameter
4538 // whose type is a class template specialization with the template
4539 // arguments of the first partial specialization, and
4540 // - the second function template has the same template parameters as the
4541 // second partial specialization and has a single function parameter
4542 // whose type is a class template specialization with the template
4543 // arguments of the second partial specialization.
4545 // Rather than synthesize function templates, we merely perform the
4546 // equivalent partial ordering by performing deduction directly on
4547 // the template arguments of the class template partial
4548 // specializations. This computation is slightly simpler than the
4549 // general problem of function template partial ordering, because
4550 // class template partial specializations are more constrained. We
4551 // know that every template parameter is deducible from the class
4552 // template partial specialization's template arguments, for
4554 SmallVector<DeducedTemplateArgument, 4> Deduced;
4555 TemplateDeductionInfo Info(Loc);
4557 QualType PT1 = PS1->getInjectedSpecializationType();
4558 QualType PT2 = PS2->getInjectedSpecializationType();
4560 // Determine whether PS1 is at least as specialized as PS2
4561 Deduced.resize(PS2->getTemplateParameters()->size());
4562 bool Better1 = !DeduceTemplateArgumentsByTypeMatch(*this,
4563 PS2->getTemplateParameters(),
4564 PT2, PT1, Info, Deduced, TDF_None,
4565 /*PartialOrdering=*/true);
4567 SmallVector<TemplateArgument, 4> DeducedArgs(Deduced.begin(),Deduced.end());
4568 InstantiatingTemplate Inst(*this, Loc, PS2, DeducedArgs, Info);
4569 Better1 = !::FinishTemplateArgumentDeduction(
4570 *this, PS2, PS1->getTemplateArgs(), Deduced, Info);
4573 // Determine whether PS2 is at least as specialized as PS1
4575 Deduced.resize(PS1->getTemplateParameters()->size());
4576 bool Better2 = !DeduceTemplateArgumentsByTypeMatch(
4577 *this, PS1->getTemplateParameters(), PT1, PT2, Info, Deduced, TDF_None,
4578 /*PartialOrdering=*/true);
4580 SmallVector<TemplateArgument, 4> DeducedArgs(Deduced.begin(),
4582 InstantiatingTemplate Inst(*this, Loc, PS1, DeducedArgs, Info);
4583 Better2 = !::FinishTemplateArgumentDeduction(
4584 *this, PS1, PS2->getTemplateArgs(), Deduced, Info);
4587 if (Better1 == Better2)
4590 return Better1 ? PS1 : PS2;
4593 /// TODO: Unify with ClassTemplatePartialSpecializationDecl version?
4594 /// May require unifying ClassTemplate(Partial)SpecializationDecl and
4595 /// VarTemplate(Partial)SpecializationDecl with a new data
4596 /// structure Template(Partial)SpecializationDecl, and
4597 /// using Template(Partial)SpecializationDecl as input type.
4598 VarTemplatePartialSpecializationDecl *
4599 Sema::getMoreSpecializedPartialSpecialization(
4600 VarTemplatePartialSpecializationDecl *PS1,
4601 VarTemplatePartialSpecializationDecl *PS2, SourceLocation Loc) {
4602 SmallVector<DeducedTemplateArgument, 4> Deduced;
4603 TemplateDeductionInfo Info(Loc);
4605 assert(PS1->getSpecializedTemplate() == PS2->getSpecializedTemplate() &&
4606 "the partial specializations being compared should specialize"
4607 " the same template.");
4608 TemplateName Name(PS1->getSpecializedTemplate());
4609 TemplateName CanonTemplate = Context.getCanonicalTemplateName(Name);
4610 QualType PT1 = Context.getTemplateSpecializationType(
4611 CanonTemplate, PS1->getTemplateArgs().data(),
4612 PS1->getTemplateArgs().size());
4613 QualType PT2 = Context.getTemplateSpecializationType(
4614 CanonTemplate, PS2->getTemplateArgs().data(),
4615 PS2->getTemplateArgs().size());
4617 // Determine whether PS1 is at least as specialized as PS2
4618 Deduced.resize(PS2->getTemplateParameters()->size());
4619 bool Better1 = !DeduceTemplateArgumentsByTypeMatch(
4620 *this, PS2->getTemplateParameters(), PT2, PT1, Info, Deduced, TDF_None,
4621 /*PartialOrdering=*/true);
4623 SmallVector<TemplateArgument, 4> DeducedArgs(Deduced.begin(),
4625 InstantiatingTemplate Inst(*this, Loc, PS2, DeducedArgs, Info);
4626 Better1 = !::FinishTemplateArgumentDeduction(*this, PS2,
4627 PS1->getTemplateArgs(),
4631 // Determine whether PS2 is at least as specialized as PS1
4633 Deduced.resize(PS1->getTemplateParameters()->size());
4634 bool Better2 = !DeduceTemplateArgumentsByTypeMatch(*this,
4635 PS1->getTemplateParameters(),
4636 PT1, PT2, Info, Deduced, TDF_None,
4637 /*PartialOrdering=*/true);
4639 SmallVector<TemplateArgument, 4> DeducedArgs(Deduced.begin(),Deduced.end());
4640 InstantiatingTemplate Inst(*this, Loc, PS1, DeducedArgs, Info);
4641 Better2 = !::FinishTemplateArgumentDeduction(*this, PS1,
4642 PS2->getTemplateArgs(),
4646 if (Better1 == Better2)
4649 return Better1? PS1 : PS2;
4653 MarkUsedTemplateParameters(ASTContext &Ctx,
4654 const TemplateArgument &TemplateArg,
4657 llvm::SmallBitVector &Used);
4659 /// \brief Mark the template parameters that are used by the given
4662 MarkUsedTemplateParameters(ASTContext &Ctx,
4666 llvm::SmallBitVector &Used) {
4667 // We can deduce from a pack expansion.
4668 if (const PackExpansionExpr *Expansion = dyn_cast<PackExpansionExpr>(E))
4669 E = Expansion->getPattern();
4671 // Skip through any implicit casts we added while type-checking, and any
4672 // substitutions performed by template alias expansion.
4674 if (const ImplicitCastExpr *ICE = dyn_cast<ImplicitCastExpr>(E))
4675 E = ICE->getSubExpr();
4676 else if (const SubstNonTypeTemplateParmExpr *Subst =
4677 dyn_cast<SubstNonTypeTemplateParmExpr>(E))
4678 E = Subst->getReplacement();
4683 // FIXME: if !OnlyDeduced, we have to walk the whole subexpression to
4684 // find other occurrences of template parameters.
4685 const DeclRefExpr *DRE = dyn_cast<DeclRefExpr>(E);
4689 const NonTypeTemplateParmDecl *NTTP
4690 = dyn_cast<NonTypeTemplateParmDecl>(DRE->getDecl());
4694 if (NTTP->getDepth() == Depth)
4695 Used[NTTP->getIndex()] = true;
4698 /// \brief Mark the template parameters that are used by the given
4699 /// nested name specifier.
4701 MarkUsedTemplateParameters(ASTContext &Ctx,
4702 NestedNameSpecifier *NNS,
4705 llvm::SmallBitVector &Used) {
4709 MarkUsedTemplateParameters(Ctx, NNS->getPrefix(), OnlyDeduced, Depth,
4711 MarkUsedTemplateParameters(Ctx, QualType(NNS->getAsType(), 0),
4712 OnlyDeduced, Depth, Used);
4715 /// \brief Mark the template parameters that are used by the given
4718 MarkUsedTemplateParameters(ASTContext &Ctx,
4722 llvm::SmallBitVector &Used) {
4723 if (TemplateDecl *Template = Name.getAsTemplateDecl()) {
4724 if (TemplateTemplateParmDecl *TTP
4725 = dyn_cast<TemplateTemplateParmDecl>(Template)) {
4726 if (TTP->getDepth() == Depth)
4727 Used[TTP->getIndex()] = true;
4732 if (QualifiedTemplateName *QTN = Name.getAsQualifiedTemplateName())
4733 MarkUsedTemplateParameters(Ctx, QTN->getQualifier(), OnlyDeduced,
4735 if (DependentTemplateName *DTN = Name.getAsDependentTemplateName())
4736 MarkUsedTemplateParameters(Ctx, DTN->getQualifier(), OnlyDeduced,
4740 /// \brief Mark the template parameters that are used by the given
4743 MarkUsedTemplateParameters(ASTContext &Ctx, QualType T,
4746 llvm::SmallBitVector &Used) {
4750 // Non-dependent types have nothing deducible
4751 if (!T->isDependentType())
4754 T = Ctx.getCanonicalType(T);
4755 switch (T->getTypeClass()) {
4757 MarkUsedTemplateParameters(Ctx,
4758 cast<PointerType>(T)->getPointeeType(),
4764 case Type::BlockPointer:
4765 MarkUsedTemplateParameters(Ctx,
4766 cast<BlockPointerType>(T)->getPointeeType(),
4772 case Type::LValueReference:
4773 case Type::RValueReference:
4774 MarkUsedTemplateParameters(Ctx,
4775 cast<ReferenceType>(T)->getPointeeType(),
4781 case Type::MemberPointer: {
4782 const MemberPointerType *MemPtr = cast<MemberPointerType>(T.getTypePtr());
4783 MarkUsedTemplateParameters(Ctx, MemPtr->getPointeeType(), OnlyDeduced,
4785 MarkUsedTemplateParameters(Ctx, QualType(MemPtr->getClass(), 0),
4786 OnlyDeduced, Depth, Used);
4790 case Type::DependentSizedArray:
4791 MarkUsedTemplateParameters(Ctx,
4792 cast<DependentSizedArrayType>(T)->getSizeExpr(),
4793 OnlyDeduced, Depth, Used);
4794 // Fall through to check the element type
4796 case Type::ConstantArray:
4797 case Type::IncompleteArray:
4798 MarkUsedTemplateParameters(Ctx,
4799 cast<ArrayType>(T)->getElementType(),
4800 OnlyDeduced, Depth, Used);
4804 case Type::ExtVector:
4805 MarkUsedTemplateParameters(Ctx,
4806 cast<VectorType>(T)->getElementType(),
4807 OnlyDeduced, Depth, Used);
4810 case Type::DependentSizedExtVector: {
4811 const DependentSizedExtVectorType *VecType
4812 = cast<DependentSizedExtVectorType>(T);
4813 MarkUsedTemplateParameters(Ctx, VecType->getElementType(), OnlyDeduced,
4815 MarkUsedTemplateParameters(Ctx, VecType->getSizeExpr(), OnlyDeduced,
4820 case Type::FunctionProto: {
4821 const FunctionProtoType *Proto = cast<FunctionProtoType>(T);
4822 MarkUsedTemplateParameters(Ctx, Proto->getReturnType(), OnlyDeduced, Depth,
4824 for (unsigned I = 0, N = Proto->getNumParams(); I != N; ++I)
4825 MarkUsedTemplateParameters(Ctx, Proto->getParamType(I), OnlyDeduced,
4830 case Type::TemplateTypeParm: {
4831 const TemplateTypeParmType *TTP = cast<TemplateTypeParmType>(T);
4832 if (TTP->getDepth() == Depth)
4833 Used[TTP->getIndex()] = true;
4837 case Type::SubstTemplateTypeParmPack: {
4838 const SubstTemplateTypeParmPackType *Subst
4839 = cast<SubstTemplateTypeParmPackType>(T);
4840 MarkUsedTemplateParameters(Ctx,
4841 QualType(Subst->getReplacedParameter(), 0),
4842 OnlyDeduced, Depth, Used);
4843 MarkUsedTemplateParameters(Ctx, Subst->getArgumentPack(),
4844 OnlyDeduced, Depth, Used);
4848 case Type::InjectedClassName:
4849 T = cast<InjectedClassNameType>(T)->getInjectedSpecializationType();
4852 case Type::TemplateSpecialization: {
4853 const TemplateSpecializationType *Spec
4854 = cast<TemplateSpecializationType>(T);
4855 MarkUsedTemplateParameters(Ctx, Spec->getTemplateName(), OnlyDeduced,
4858 // C++0x [temp.deduct.type]p9:
4859 // If the template argument list of P contains a pack expansion that is
4860 // not the last template argument, the entire template argument list is a
4861 // non-deduced context.
4863 hasPackExpansionBeforeEnd(Spec->getArgs(), Spec->getNumArgs()))
4866 for (unsigned I = 0, N = Spec->getNumArgs(); I != N; ++I)
4867 MarkUsedTemplateParameters(Ctx, Spec->getArg(I), OnlyDeduced, Depth,
4874 MarkUsedTemplateParameters(Ctx,
4875 cast<ComplexType>(T)->getElementType(),
4876 OnlyDeduced, Depth, Used);
4881 MarkUsedTemplateParameters(Ctx,
4882 cast<AtomicType>(T)->getValueType(),
4883 OnlyDeduced, Depth, Used);
4886 case Type::DependentName:
4888 MarkUsedTemplateParameters(Ctx,
4889 cast<DependentNameType>(T)->getQualifier(),
4890 OnlyDeduced, Depth, Used);
4893 case Type::DependentTemplateSpecialization: {
4894 // C++14 [temp.deduct.type]p5:
4895 // The non-deduced contexts are:
4896 // -- The nested-name-specifier of a type that was specified using a
4899 // C++14 [temp.deduct.type]p6:
4900 // When a type name is specified in a way that includes a non-deduced
4901 // context, all of the types that comprise that type name are also
4906 const DependentTemplateSpecializationType *Spec
4907 = cast<DependentTemplateSpecializationType>(T);
4909 MarkUsedTemplateParameters(Ctx, Spec->getQualifier(),
4910 OnlyDeduced, Depth, Used);
4912 for (unsigned I = 0, N = Spec->getNumArgs(); I != N; ++I)
4913 MarkUsedTemplateParameters(Ctx, Spec->getArg(I), OnlyDeduced, Depth,
4920 MarkUsedTemplateParameters(Ctx,
4921 cast<TypeOfType>(T)->getUnderlyingType(),
4922 OnlyDeduced, Depth, Used);
4925 case Type::TypeOfExpr:
4927 MarkUsedTemplateParameters(Ctx,
4928 cast<TypeOfExprType>(T)->getUnderlyingExpr(),
4929 OnlyDeduced, Depth, Used);
4932 case Type::Decltype:
4934 MarkUsedTemplateParameters(Ctx,
4935 cast<DecltypeType>(T)->getUnderlyingExpr(),
4936 OnlyDeduced, Depth, Used);
4939 case Type::UnaryTransform:
4941 MarkUsedTemplateParameters(Ctx,
4942 cast<UnaryTransformType>(T)->getUnderlyingType(),
4943 OnlyDeduced, Depth, Used);
4946 case Type::PackExpansion:
4947 MarkUsedTemplateParameters(Ctx,
4948 cast<PackExpansionType>(T)->getPattern(),
4949 OnlyDeduced, Depth, Used);
4953 MarkUsedTemplateParameters(Ctx,
4954 cast<AutoType>(T)->getDeducedType(),
4955 OnlyDeduced, Depth, Used);
4957 // None of these types have any template parameters in them.
4959 case Type::VariableArray:
4960 case Type::FunctionNoProto:
4963 case Type::ObjCInterface:
4964 case Type::ObjCObject:
4965 case Type::ObjCObjectPointer:
4966 case Type::UnresolvedUsing:
4967 #define TYPE(Class, Base)
4968 #define ABSTRACT_TYPE(Class, Base)
4969 #define DEPENDENT_TYPE(Class, Base)
4970 #define NON_CANONICAL_TYPE(Class, Base) case Type::Class:
4971 #include "clang/AST/TypeNodes.def"
4976 /// \brief Mark the template parameters that are used by this
4977 /// template argument.
4979 MarkUsedTemplateParameters(ASTContext &Ctx,
4980 const TemplateArgument &TemplateArg,
4983 llvm::SmallBitVector &Used) {
4984 switch (TemplateArg.getKind()) {
4985 case TemplateArgument::Null:
4986 case TemplateArgument::Integral:
4987 case TemplateArgument::Declaration:
4990 case TemplateArgument::NullPtr:
4991 MarkUsedTemplateParameters(Ctx, TemplateArg.getNullPtrType(), OnlyDeduced,
4995 case TemplateArgument::Type:
4996 MarkUsedTemplateParameters(Ctx, TemplateArg.getAsType(), OnlyDeduced,
5000 case TemplateArgument::Template:
5001 case TemplateArgument::TemplateExpansion:
5002 MarkUsedTemplateParameters(Ctx,
5003 TemplateArg.getAsTemplateOrTemplatePattern(),
5004 OnlyDeduced, Depth, Used);
5007 case TemplateArgument::Expression:
5008 MarkUsedTemplateParameters(Ctx, TemplateArg.getAsExpr(), OnlyDeduced,
5012 case TemplateArgument::Pack:
5013 for (const auto &P : TemplateArg.pack_elements())
5014 MarkUsedTemplateParameters(Ctx, P, OnlyDeduced, Depth, Used);
5019 /// \brief Mark which template parameters can be deduced from a given
5020 /// template argument list.
5022 /// \param TemplateArgs the template argument list from which template
5023 /// parameters will be deduced.
5025 /// \param Used a bit vector whose elements will be set to \c true
5026 /// to indicate when the corresponding template parameter will be
5029 Sema::MarkUsedTemplateParameters(const TemplateArgumentList &TemplateArgs,
5030 bool OnlyDeduced, unsigned Depth,
5031 llvm::SmallBitVector &Used) {
5032 // C++0x [temp.deduct.type]p9:
5033 // If the template argument list of P contains a pack expansion that is not
5034 // the last template argument, the entire template argument list is a
5035 // non-deduced context.
5037 hasPackExpansionBeforeEnd(TemplateArgs.data(), TemplateArgs.size()))
5040 for (unsigned I = 0, N = TemplateArgs.size(); I != N; ++I)
5041 ::MarkUsedTemplateParameters(Context, TemplateArgs[I], OnlyDeduced,
5045 /// \brief Marks all of the template parameters that will be deduced by a
5046 /// call to the given function template.
5047 void Sema::MarkDeducedTemplateParameters(
5048 ASTContext &Ctx, const FunctionTemplateDecl *FunctionTemplate,
5049 llvm::SmallBitVector &Deduced) {
5050 TemplateParameterList *TemplateParams
5051 = FunctionTemplate->getTemplateParameters();
5053 Deduced.resize(TemplateParams->size());
5055 FunctionDecl *Function = FunctionTemplate->getTemplatedDecl();
5056 for (unsigned I = 0, N = Function->getNumParams(); I != N; ++I)
5057 ::MarkUsedTemplateParameters(Ctx, Function->getParamDecl(I)->getType(),
5058 true, TemplateParams->getDepth(), Deduced);
5061 bool hasDeducibleTemplateParameters(Sema &S,
5062 FunctionTemplateDecl *FunctionTemplate,
5064 if (!T->isDependentType())
5067 TemplateParameterList *TemplateParams
5068 = FunctionTemplate->getTemplateParameters();
5069 llvm::SmallBitVector Deduced(TemplateParams->size());
5070 ::MarkUsedTemplateParameters(S.Context, T, true, TemplateParams->getDepth(),
5073 return Deduced.any();