1 //===------- SemaTemplateDeduction.cpp - Template Argument Deduction ------===/
3 // The LLVM Compiler Infrastructure
5 // This file is distributed under the University of Illinois Open Source
6 // License. See LICENSE.TXT for details.
7 //===----------------------------------------------------------------------===/
9 // This file implements C++ template argument deduction.
11 //===----------------------------------------------------------------------===/
13 #include "clang/Sema/TemplateDeduction.h"
14 #include "TreeTransform.h"
15 #include "clang/AST/ASTContext.h"
16 #include "clang/AST/ASTLambda.h"
17 #include "clang/AST/DeclObjC.h"
18 #include "clang/AST/DeclTemplate.h"
19 #include "clang/AST/Expr.h"
20 #include "clang/AST/ExprCXX.h"
21 #include "clang/AST/StmtVisitor.h"
22 #include "clang/AST/TypeOrdering.h"
23 #include "clang/Sema/DeclSpec.h"
24 #include "clang/Sema/Sema.h"
25 #include "clang/Sema/Template.h"
26 #include "llvm/ADT/SmallBitVector.h"
31 /// \brief Various flags that control template argument deduction.
33 /// These flags can be bitwise-OR'd together.
34 enum TemplateDeductionFlags {
35 /// \brief No template argument deduction flags, which indicates the
36 /// strictest results for template argument deduction (as used for, e.g.,
37 /// matching class template partial specializations).
39 /// \brief Within template argument deduction from a function call, we are
40 /// matching with a parameter type for which the original parameter was
42 TDF_ParamWithReferenceType = 0x1,
43 /// \brief Within template argument deduction from a function call, we
44 /// are matching in a case where we ignore cv-qualifiers.
45 TDF_IgnoreQualifiers = 0x02,
46 /// \brief Within template argument deduction from a function call,
47 /// we are matching in a case where we can perform template argument
48 /// deduction from a template-id of a derived class of the argument type.
49 TDF_DerivedClass = 0x04,
50 /// \brief Allow non-dependent types to differ, e.g., when performing
51 /// template argument deduction from a function call where conversions
53 TDF_SkipNonDependent = 0x08,
54 /// \brief Whether we are performing template argument deduction for
55 /// parameters and arguments in a top-level template argument
56 TDF_TopLevelParameterTypeList = 0x10,
57 /// \brief Within template argument deduction from overload resolution per
58 /// C++ [over.over] allow matching function types that are compatible in
59 /// terms of noreturn and default calling convention adjustments.
60 TDF_InOverloadResolution = 0x20
64 using namespace clang;
66 /// \brief Compare two APSInts, extending and switching the sign as
67 /// necessary to compare their values regardless of underlying type.
68 static bool hasSameExtendedValue(llvm::APSInt X, llvm::APSInt Y) {
69 if (Y.getBitWidth() > X.getBitWidth())
70 X = X.extend(Y.getBitWidth());
71 else if (Y.getBitWidth() < X.getBitWidth())
72 Y = Y.extend(X.getBitWidth());
74 // If there is a signedness mismatch, correct it.
75 if (X.isSigned() != Y.isSigned()) {
76 // If the signed value is negative, then the values cannot be the same.
77 if ((Y.isSigned() && Y.isNegative()) || (X.isSigned() && X.isNegative()))
87 static Sema::TemplateDeductionResult
88 DeduceTemplateArguments(Sema &S,
89 TemplateParameterList *TemplateParams,
90 const TemplateArgument &Param,
92 TemplateDeductionInfo &Info,
93 SmallVectorImpl<DeducedTemplateArgument> &Deduced);
95 static Sema::TemplateDeductionResult
96 DeduceTemplateArgumentsByTypeMatch(Sema &S,
97 TemplateParameterList *TemplateParams,
100 TemplateDeductionInfo &Info,
101 SmallVectorImpl<DeducedTemplateArgument> &
104 bool PartialOrdering = false,
105 bool DeducedFromArrayBound = false);
107 static Sema::TemplateDeductionResult
108 DeduceTemplateArguments(Sema &S, TemplateParameterList *TemplateParams,
109 ArrayRef<TemplateArgument> Params,
110 ArrayRef<TemplateArgument> Args,
111 TemplateDeductionInfo &Info,
112 SmallVectorImpl<DeducedTemplateArgument> &Deduced,
113 bool NumberOfArgumentsMustMatch);
115 static void MarkUsedTemplateParameters(ASTContext &Ctx,
116 const TemplateArgument &TemplateArg,
117 bool OnlyDeduced, unsigned Depth,
118 llvm::SmallBitVector &Used);
120 static void MarkUsedTemplateParameters(ASTContext &Ctx, QualType T,
121 bool OnlyDeduced, unsigned Level,
122 llvm::SmallBitVector &Deduced);
124 /// \brief If the given expression is of a form that permits the deduction
125 /// of a non-type template parameter, return the declaration of that
126 /// non-type template parameter.
127 static NonTypeTemplateParmDecl *
128 getDeducedParameterFromExpr(TemplateDeductionInfo &Info, Expr *E) {
129 // If we are within an alias template, the expression may have undergone
130 // any number of parameter substitutions already.
132 if (ImplicitCastExpr *IC = dyn_cast<ImplicitCastExpr>(E))
133 E = IC->getSubExpr();
134 else if (SubstNonTypeTemplateParmExpr *Subst =
135 dyn_cast<SubstNonTypeTemplateParmExpr>(E))
136 E = Subst->getReplacement();
141 if (DeclRefExpr *DRE = dyn_cast<DeclRefExpr>(E))
142 if (auto *NTTP = dyn_cast<NonTypeTemplateParmDecl>(DRE->getDecl()))
143 if (NTTP->getDepth() == Info.getDeducedDepth())
149 /// \brief Determine whether two declaration pointers refer to the same
151 static bool isSameDeclaration(Decl *X, Decl *Y) {
152 if (NamedDecl *NX = dyn_cast<NamedDecl>(X))
153 X = NX->getUnderlyingDecl();
154 if (NamedDecl *NY = dyn_cast<NamedDecl>(Y))
155 Y = NY->getUnderlyingDecl();
157 return X->getCanonicalDecl() == Y->getCanonicalDecl();
160 /// \brief Verify that the given, deduced template arguments are compatible.
162 /// \returns The deduced template argument, or a NULL template argument if
163 /// the deduced template arguments were incompatible.
164 static DeducedTemplateArgument
165 checkDeducedTemplateArguments(ASTContext &Context,
166 const DeducedTemplateArgument &X,
167 const DeducedTemplateArgument &Y) {
168 // We have no deduction for one or both of the arguments; they're compatible.
174 // If we have two non-type template argument values deduced for the same
175 // parameter, they must both match the type of the parameter, and thus must
176 // match each other's type. As we're only keeping one of them, we must check
177 // for that now. The exception is that if either was deduced from an array
178 // bound, the type is permitted to differ.
179 if (!X.wasDeducedFromArrayBound() && !Y.wasDeducedFromArrayBound()) {
180 QualType XType = X.getNonTypeTemplateArgumentType();
181 if (!XType.isNull()) {
182 QualType YType = Y.getNonTypeTemplateArgumentType();
183 if (YType.isNull() || !Context.hasSameType(XType, YType))
184 return DeducedTemplateArgument();
188 switch (X.getKind()) {
189 case TemplateArgument::Null:
190 llvm_unreachable("Non-deduced template arguments handled above");
192 case TemplateArgument::Type:
193 // If two template type arguments have the same type, they're compatible.
194 if (Y.getKind() == TemplateArgument::Type &&
195 Context.hasSameType(X.getAsType(), Y.getAsType()))
198 // If one of the two arguments was deduced from an array bound, the other
200 if (X.wasDeducedFromArrayBound() != Y.wasDeducedFromArrayBound())
201 return X.wasDeducedFromArrayBound() ? Y : X;
203 // The arguments are not compatible.
204 return DeducedTemplateArgument();
206 case TemplateArgument::Integral:
207 // If we deduced a constant in one case and either a dependent expression or
208 // declaration in another case, keep the integral constant.
209 // If both are integral constants with the same value, keep that value.
210 if (Y.getKind() == TemplateArgument::Expression ||
211 Y.getKind() == TemplateArgument::Declaration ||
212 (Y.getKind() == TemplateArgument::Integral &&
213 hasSameExtendedValue(X.getAsIntegral(), Y.getAsIntegral())))
214 return X.wasDeducedFromArrayBound() ? Y : X;
216 // All other combinations are incompatible.
217 return DeducedTemplateArgument();
219 case TemplateArgument::Template:
220 if (Y.getKind() == TemplateArgument::Template &&
221 Context.hasSameTemplateName(X.getAsTemplate(), Y.getAsTemplate()))
224 // All other combinations are incompatible.
225 return DeducedTemplateArgument();
227 case TemplateArgument::TemplateExpansion:
228 if (Y.getKind() == TemplateArgument::TemplateExpansion &&
229 Context.hasSameTemplateName(X.getAsTemplateOrTemplatePattern(),
230 Y.getAsTemplateOrTemplatePattern()))
233 // All other combinations are incompatible.
234 return DeducedTemplateArgument();
236 case TemplateArgument::Expression: {
237 if (Y.getKind() != TemplateArgument::Expression)
238 return checkDeducedTemplateArguments(Context, Y, X);
240 // Compare the expressions for equality
241 llvm::FoldingSetNodeID ID1, ID2;
242 X.getAsExpr()->Profile(ID1, Context, true);
243 Y.getAsExpr()->Profile(ID2, Context, true);
245 return X.wasDeducedFromArrayBound() ? Y : X;
247 // Differing dependent expressions are incompatible.
248 return DeducedTemplateArgument();
251 case TemplateArgument::Declaration:
252 assert(!X.wasDeducedFromArrayBound());
254 // If we deduced a declaration and a dependent expression, keep the
256 if (Y.getKind() == TemplateArgument::Expression)
259 // If we deduced a declaration and an integral constant, keep the
260 // integral constant and whichever type did not come from an array
262 if (Y.getKind() == TemplateArgument::Integral) {
263 if (Y.wasDeducedFromArrayBound())
264 return TemplateArgument(Context, Y.getAsIntegral(),
265 X.getParamTypeForDecl());
269 // If we deduced two declarations, make sure they they refer to the
271 if (Y.getKind() == TemplateArgument::Declaration &&
272 isSameDeclaration(X.getAsDecl(), Y.getAsDecl()))
275 // All other combinations are incompatible.
276 return DeducedTemplateArgument();
278 case TemplateArgument::NullPtr:
279 // If we deduced a null pointer and a dependent expression, keep the
281 if (Y.getKind() == TemplateArgument::Expression)
284 // If we deduced a null pointer and an integral constant, keep the
285 // integral constant.
286 if (Y.getKind() == TemplateArgument::Integral)
289 // If we deduced two null pointers, they are the same.
290 if (Y.getKind() == TemplateArgument::NullPtr)
293 // All other combinations are incompatible.
294 return DeducedTemplateArgument();
296 case TemplateArgument::Pack:
297 if (Y.getKind() != TemplateArgument::Pack ||
298 X.pack_size() != Y.pack_size())
299 return DeducedTemplateArgument();
301 llvm::SmallVector<TemplateArgument, 8> NewPack;
302 for (TemplateArgument::pack_iterator XA = X.pack_begin(),
303 XAEnd = X.pack_end(),
305 XA != XAEnd; ++XA, ++YA) {
306 TemplateArgument Merged = checkDeducedTemplateArguments(
307 Context, DeducedTemplateArgument(*XA, X.wasDeducedFromArrayBound()),
308 DeducedTemplateArgument(*YA, Y.wasDeducedFromArrayBound()));
310 return DeducedTemplateArgument();
311 NewPack.push_back(Merged);
314 return DeducedTemplateArgument(
315 TemplateArgument::CreatePackCopy(Context, NewPack),
316 X.wasDeducedFromArrayBound() && Y.wasDeducedFromArrayBound());
319 llvm_unreachable("Invalid TemplateArgument Kind!");
322 /// \brief Deduce the value of the given non-type template parameter
323 /// as the given deduced template argument. All non-type template parameter
324 /// deduction is funneled through here.
325 static Sema::TemplateDeductionResult DeduceNonTypeTemplateArgument(
326 Sema &S, TemplateParameterList *TemplateParams,
327 NonTypeTemplateParmDecl *NTTP, const DeducedTemplateArgument &NewDeduced,
328 QualType ValueType, TemplateDeductionInfo &Info,
329 SmallVectorImpl<DeducedTemplateArgument> &Deduced) {
330 assert(NTTP->getDepth() == Info.getDeducedDepth() &&
331 "deducing non-type template argument with wrong depth");
333 DeducedTemplateArgument Result = checkDeducedTemplateArguments(
334 S.Context, Deduced[NTTP->getIndex()], NewDeduced);
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 if (!S.getLangOpts().CPlusPlus1z)
344 return Sema::TDK_Success;
346 if (NTTP->isExpandedParameterPack())
347 // FIXME: We may still need to deduce parts of the type here! But we
348 // don't have any way to find which slice of the type to use, and the
349 // type stored on the NTTP itself is nonsense. Perhaps the type of an
350 // expanded NTTP should be a pack expansion type?
351 return Sema::TDK_Success;
353 // Get the type of the parameter for deduction.
354 QualType ParamType = NTTP->getType();
355 if (auto *Expansion = dyn_cast<PackExpansionType>(ParamType))
356 ParamType = Expansion->getPattern();
358 // FIXME: It's not clear how deduction of a parameter of reference
359 // type from an argument (of non-reference type) should be performed.
360 // For now, we just remove reference types from both sides and let
361 // the final check for matching types sort out the mess.
362 return DeduceTemplateArgumentsByTypeMatch(
363 S, TemplateParams, ParamType.getNonReferenceType(),
364 ValueType.getNonReferenceType(), Info, Deduced, TDF_SkipNonDependent,
365 /*PartialOrdering=*/false,
366 /*ArrayBound=*/NewDeduced.wasDeducedFromArrayBound());
369 /// \brief Deduce the value of the given non-type template parameter
370 /// from the given integral constant.
371 static Sema::TemplateDeductionResult DeduceNonTypeTemplateArgument(
372 Sema &S, TemplateParameterList *TemplateParams,
373 NonTypeTemplateParmDecl *NTTP, const llvm::APSInt &Value,
374 QualType ValueType, bool DeducedFromArrayBound, TemplateDeductionInfo &Info,
375 SmallVectorImpl<DeducedTemplateArgument> &Deduced) {
376 return DeduceNonTypeTemplateArgument(
377 S, TemplateParams, NTTP,
378 DeducedTemplateArgument(S.Context, Value, ValueType,
379 DeducedFromArrayBound),
380 ValueType, Info, Deduced);
383 /// \brief Deduce the value of the given non-type template parameter
384 /// from the given null pointer template argument type.
385 static Sema::TemplateDeductionResult DeduceNullPtrTemplateArgument(
386 Sema &S, TemplateParameterList *TemplateParams,
387 NonTypeTemplateParmDecl *NTTP, QualType NullPtrType,
388 TemplateDeductionInfo &Info,
389 SmallVectorImpl<DeducedTemplateArgument> &Deduced) {
391 S.ImpCastExprToType(new (S.Context) CXXNullPtrLiteralExpr(
392 S.Context.NullPtrTy, NTTP->getLocation()),
393 NullPtrType, CK_NullToPointer)
395 return DeduceNonTypeTemplateArgument(S, TemplateParams, NTTP,
396 DeducedTemplateArgument(Value),
397 Value->getType(), Info, Deduced);
400 /// \brief Deduce the value of the given non-type template parameter
401 /// from the given type- or value-dependent expression.
403 /// \returns true if deduction succeeded, false otherwise.
404 static Sema::TemplateDeductionResult DeduceNonTypeTemplateArgument(
405 Sema &S, TemplateParameterList *TemplateParams,
406 NonTypeTemplateParmDecl *NTTP, Expr *Value, TemplateDeductionInfo &Info,
407 SmallVectorImpl<DeducedTemplateArgument> &Deduced) {
408 return DeduceNonTypeTemplateArgument(S, TemplateParams, NTTP,
409 DeducedTemplateArgument(Value),
410 Value->getType(), Info, Deduced);
413 /// \brief Deduce the value of the given non-type template parameter
414 /// from the given declaration.
416 /// \returns true if deduction succeeded, false otherwise.
417 static Sema::TemplateDeductionResult DeduceNonTypeTemplateArgument(
418 Sema &S, TemplateParameterList *TemplateParams,
419 NonTypeTemplateParmDecl *NTTP, ValueDecl *D, QualType T,
420 TemplateDeductionInfo &Info,
421 SmallVectorImpl<DeducedTemplateArgument> &Deduced) {
422 D = D ? cast<ValueDecl>(D->getCanonicalDecl()) : nullptr;
423 TemplateArgument New(D, T);
424 return DeduceNonTypeTemplateArgument(
425 S, TemplateParams, NTTP, DeducedTemplateArgument(New), T, Info, Deduced);
428 static Sema::TemplateDeductionResult
429 DeduceTemplateArguments(Sema &S,
430 TemplateParameterList *TemplateParams,
433 TemplateDeductionInfo &Info,
434 SmallVectorImpl<DeducedTemplateArgument> &Deduced) {
435 TemplateDecl *ParamDecl = Param.getAsTemplateDecl();
437 // The parameter type is dependent and is not a template template parameter,
438 // so there is nothing that we can deduce.
439 return Sema::TDK_Success;
442 if (TemplateTemplateParmDecl *TempParam
443 = dyn_cast<TemplateTemplateParmDecl>(ParamDecl)) {
444 // If we're not deducing at this depth, there's nothing to deduce.
445 if (TempParam->getDepth() != Info.getDeducedDepth())
446 return Sema::TDK_Success;
448 DeducedTemplateArgument NewDeduced(S.Context.getCanonicalTemplateName(Arg));
449 DeducedTemplateArgument Result = checkDeducedTemplateArguments(S.Context,
450 Deduced[TempParam->getIndex()],
452 if (Result.isNull()) {
453 Info.Param = TempParam;
454 Info.FirstArg = Deduced[TempParam->getIndex()];
455 Info.SecondArg = NewDeduced;
456 return Sema::TDK_Inconsistent;
459 Deduced[TempParam->getIndex()] = Result;
460 return Sema::TDK_Success;
463 // Verify that the two template names are equivalent.
464 if (S.Context.hasSameTemplateName(Param, Arg))
465 return Sema::TDK_Success;
467 // Mismatch of non-dependent template parameter to argument.
468 Info.FirstArg = TemplateArgument(Param);
469 Info.SecondArg = TemplateArgument(Arg);
470 return Sema::TDK_NonDeducedMismatch;
473 /// \brief Deduce the template arguments by comparing the template parameter
474 /// type (which is a template-id) with the template argument type.
476 /// \param S the Sema
478 /// \param TemplateParams the template parameters that we are deducing
480 /// \param Param the parameter type
482 /// \param Arg the argument type
484 /// \param Info information about the template argument deduction itself
486 /// \param Deduced the deduced template arguments
488 /// \returns the result of template argument deduction so far. Note that a
489 /// "success" result means that template argument deduction has not yet failed,
490 /// but it may still fail, later, for other reasons.
491 static Sema::TemplateDeductionResult
492 DeduceTemplateArguments(Sema &S,
493 TemplateParameterList *TemplateParams,
494 const TemplateSpecializationType *Param,
496 TemplateDeductionInfo &Info,
497 SmallVectorImpl<DeducedTemplateArgument> &Deduced) {
498 assert(Arg.isCanonical() && "Argument type must be canonical");
500 // Check whether the template argument is a dependent template-id.
501 if (const TemplateSpecializationType *SpecArg
502 = dyn_cast<TemplateSpecializationType>(Arg)) {
503 // Perform template argument deduction for the template name.
504 if (Sema::TemplateDeductionResult Result
505 = DeduceTemplateArguments(S, TemplateParams,
506 Param->getTemplateName(),
507 SpecArg->getTemplateName(),
512 // Perform template argument deduction on each template
513 // argument. Ignore any missing/extra arguments, since they could be
514 // filled in by default arguments.
515 return DeduceTemplateArguments(S, TemplateParams,
516 Param->template_arguments(),
517 SpecArg->template_arguments(), Info, Deduced,
518 /*NumberOfArgumentsMustMatch=*/false);
521 // If the argument type is a class template specialization, we
522 // perform template argument deduction using its template
524 const RecordType *RecordArg = dyn_cast<RecordType>(Arg);
526 Info.FirstArg = TemplateArgument(QualType(Param, 0));
527 Info.SecondArg = TemplateArgument(Arg);
528 return Sema::TDK_NonDeducedMismatch;
531 ClassTemplateSpecializationDecl *SpecArg
532 = dyn_cast<ClassTemplateSpecializationDecl>(RecordArg->getDecl());
534 Info.FirstArg = TemplateArgument(QualType(Param, 0));
535 Info.SecondArg = TemplateArgument(Arg);
536 return Sema::TDK_NonDeducedMismatch;
539 // Perform template argument deduction for the template name.
540 if (Sema::TemplateDeductionResult Result
541 = DeduceTemplateArguments(S,
543 Param->getTemplateName(),
544 TemplateName(SpecArg->getSpecializedTemplate()),
548 // Perform template argument deduction for the template arguments.
549 return DeduceTemplateArguments(S, TemplateParams, Param->template_arguments(),
550 SpecArg->getTemplateArgs().asArray(), Info,
551 Deduced, /*NumberOfArgumentsMustMatch=*/true);
554 /// \brief Determines whether the given type is an opaque type that
555 /// might be more qualified when instantiated.
556 static bool IsPossiblyOpaquelyQualifiedType(QualType T) {
557 switch (T->getTypeClass()) {
558 case Type::TypeOfExpr:
560 case Type::DependentName:
562 case Type::UnresolvedUsing:
563 case Type::TemplateTypeParm:
566 case Type::ConstantArray:
567 case Type::IncompleteArray:
568 case Type::VariableArray:
569 case Type::DependentSizedArray:
570 return IsPossiblyOpaquelyQualifiedType(
571 cast<ArrayType>(T)->getElementType());
578 /// \brief Retrieve the depth and index of a template parameter.
579 static std::pair<unsigned, unsigned>
580 getDepthAndIndex(NamedDecl *ND) {
581 if (TemplateTypeParmDecl *TTP = dyn_cast<TemplateTypeParmDecl>(ND))
582 return std::make_pair(TTP->getDepth(), TTP->getIndex());
584 if (NonTypeTemplateParmDecl *NTTP = dyn_cast<NonTypeTemplateParmDecl>(ND))
585 return std::make_pair(NTTP->getDepth(), NTTP->getIndex());
587 TemplateTemplateParmDecl *TTP = cast<TemplateTemplateParmDecl>(ND);
588 return std::make_pair(TTP->getDepth(), TTP->getIndex());
591 /// \brief Retrieve the depth and index of an unexpanded parameter pack.
592 static std::pair<unsigned, unsigned>
593 getDepthAndIndex(UnexpandedParameterPack UPP) {
594 if (const TemplateTypeParmType *TTP
595 = UPP.first.dyn_cast<const TemplateTypeParmType *>())
596 return std::make_pair(TTP->getDepth(), TTP->getIndex());
598 return getDepthAndIndex(UPP.first.get<NamedDecl *>());
601 /// \brief Helper function to build a TemplateParameter when we don't
602 /// know its type statically.
603 static TemplateParameter makeTemplateParameter(Decl *D) {
604 if (TemplateTypeParmDecl *TTP = dyn_cast<TemplateTypeParmDecl>(D))
605 return TemplateParameter(TTP);
606 if (NonTypeTemplateParmDecl *NTTP = dyn_cast<NonTypeTemplateParmDecl>(D))
607 return TemplateParameter(NTTP);
609 return TemplateParameter(cast<TemplateTemplateParmDecl>(D));
612 /// A pack that we're currently deducing.
613 struct clang::DeducedPack {
614 DeducedPack(unsigned Index) : Index(Index), Outer(nullptr) {}
616 // The index of the pack.
619 // The old value of the pack before we started deducing it.
620 DeducedTemplateArgument Saved;
622 // A deferred value of this pack from an inner deduction, that couldn't be
623 // deduced because this deduction hadn't happened yet.
624 DeducedTemplateArgument DeferredDeduction;
626 // The new value of the pack.
627 SmallVector<DeducedTemplateArgument, 4> New;
629 // The outer deduction for this pack, if any.
634 /// A scope in which we're performing pack deduction.
635 class PackDeductionScope {
637 PackDeductionScope(Sema &S, TemplateParameterList *TemplateParams,
638 SmallVectorImpl<DeducedTemplateArgument> &Deduced,
639 TemplateDeductionInfo &Info, TemplateArgument Pattern)
640 : S(S), TemplateParams(TemplateParams), Deduced(Deduced), Info(Info) {
641 // Dig out the partially-substituted pack, if there is one.
642 const TemplateArgument *PartialPackArgs = nullptr;
643 unsigned NumPartialPackArgs = 0;
644 std::pair<unsigned, unsigned> PartialPackDepthIndex(-1u, -1u);
645 if (auto *Scope = S.CurrentInstantiationScope)
646 if (auto *Partial = Scope->getPartiallySubstitutedPack(
647 &PartialPackArgs, &NumPartialPackArgs))
648 PartialPackDepthIndex = getDepthAndIndex(Partial);
650 // Compute the set of template parameter indices that correspond to
651 // parameter packs expanded by the pack expansion.
653 llvm::SmallBitVector SawIndices(TemplateParams->size());
655 auto AddPack = [&](unsigned Index) {
656 if (SawIndices[Index])
658 SawIndices[Index] = true;
660 // Save the deduced template argument for the parameter pack expanded
661 // by this pack expansion, then clear out the deduction.
662 DeducedPack Pack(Index);
663 Pack.Saved = Deduced[Index];
664 Deduced[Index] = TemplateArgument();
666 Packs.push_back(Pack);
669 // First look for unexpanded packs in the pattern.
670 SmallVector<UnexpandedParameterPack, 2> Unexpanded;
671 S.collectUnexpandedParameterPacks(Pattern, Unexpanded);
672 for (unsigned I = 0, N = Unexpanded.size(); I != N; ++I) {
673 unsigned Depth, Index;
674 std::tie(Depth, Index) = getDepthAndIndex(Unexpanded[I]);
675 if (Depth == Info.getDeducedDepth())
678 assert(!Packs.empty() && "Pack expansion without unexpanded packs?");
680 // This pack expansion will have been partially expanded iff the only
681 // unexpanded parameter pack within it is the partially-substituted pack.
682 IsPartiallyExpanded =
684 PartialPackDepthIndex ==
685 std::make_pair(Info.getDeducedDepth(), Packs.front().Index);
687 // Skip over the pack elements that were expanded into separate arguments.
688 if (IsPartiallyExpanded)
689 PackElements += NumPartialPackArgs;
691 // We can also have deduced template parameters that do not actually
692 // appear in the pattern, but can be deduced by it (the type of a non-type
693 // template parameter pack, in particular). These won't have prevented us
694 // from partially expanding the pack.
695 llvm::SmallBitVector Used(TemplateParams->size());
696 MarkUsedTemplateParameters(S.Context, Pattern, /*OnlyDeduced*/true,
697 Info.getDeducedDepth(), Used);
698 for (int Index = Used.find_first(); Index != -1;
699 Index = Used.find_next(Index))
700 if (TemplateParams->getParam(Index)->isParameterPack())
704 for (auto &Pack : Packs) {
705 if (Info.PendingDeducedPacks.size() > Pack.Index)
706 Pack.Outer = Info.PendingDeducedPacks[Pack.Index];
708 Info.PendingDeducedPacks.resize(Pack.Index + 1);
709 Info.PendingDeducedPacks[Pack.Index] = &Pack;
711 if (PartialPackDepthIndex ==
712 std::make_pair(Info.getDeducedDepth(), Pack.Index)) {
713 Pack.New.append(PartialPackArgs, PartialPackArgs + NumPartialPackArgs);
714 // We pre-populate the deduced value of the partially-substituted
715 // pack with the specified value. This is not entirely correct: the
716 // value is supposed to have been substituted, not deduced, but the
717 // cases where this is observable require an exact type match anyway.
719 // FIXME: If we could represent a "depth i, index j, pack elem k"
720 // parameter, we could substitute the partially-substituted pack
721 // everywhere and avoid this.
722 if (Pack.New.size() > PackElements)
723 Deduced[Pack.Index] = Pack.New[PackElements];
728 ~PackDeductionScope() {
729 for (auto &Pack : Packs)
730 Info.PendingDeducedPacks[Pack.Index] = Pack.Outer;
733 /// Determine whether this pack has already been partially expanded into a
734 /// sequence of (prior) function parameters / template arguments.
735 bool isPartiallyExpanded() { return IsPartiallyExpanded; }
737 /// Move to deducing the next element in each pack that is being deduced.
738 void nextPackElement() {
739 // Capture the deduced template arguments for each parameter pack expanded
740 // by this pack expansion, add them to the list of arguments we've deduced
741 // for that pack, then clear out the deduced argument.
742 for (auto &Pack : Packs) {
743 DeducedTemplateArgument &DeducedArg = Deduced[Pack.Index];
744 if (!Pack.New.empty() || !DeducedArg.isNull()) {
745 while (Pack.New.size() < PackElements)
746 Pack.New.push_back(DeducedTemplateArgument());
747 if (Pack.New.size() == PackElements)
748 Pack.New.push_back(DeducedArg);
750 Pack.New[PackElements] = DeducedArg;
751 DeducedArg = Pack.New.size() > PackElements + 1
752 ? Pack.New[PackElements + 1]
753 : DeducedTemplateArgument();
759 /// \brief Finish template argument deduction for a set of argument packs,
760 /// producing the argument packs and checking for consistency with prior
762 Sema::TemplateDeductionResult finish() {
763 // Build argument packs for each of the parameter packs expanded by this
765 for (auto &Pack : Packs) {
766 // Put back the old value for this pack.
767 Deduced[Pack.Index] = Pack.Saved;
769 // Build or find a new value for this pack.
770 DeducedTemplateArgument NewPack;
771 if (PackElements && Pack.New.empty()) {
772 if (Pack.DeferredDeduction.isNull()) {
773 // We were not able to deduce anything for this parameter pack
774 // (because it only appeared in non-deduced contexts), so just
775 // restore the saved argument pack.
779 NewPack = Pack.DeferredDeduction;
780 Pack.DeferredDeduction = TemplateArgument();
781 } else if (Pack.New.empty()) {
782 // If we deduced an empty argument pack, create it now.
783 NewPack = DeducedTemplateArgument(TemplateArgument::getEmptyPack());
785 TemplateArgument *ArgumentPack =
786 new (S.Context) TemplateArgument[Pack.New.size()];
787 std::copy(Pack.New.begin(), Pack.New.end(), ArgumentPack);
788 NewPack = DeducedTemplateArgument(
789 TemplateArgument(llvm::makeArrayRef(ArgumentPack, Pack.New.size())),
790 // FIXME: This is wrong, it's possible that some pack elements are
791 // deduced from an array bound and others are not:
792 // template<typename ...T, T ...V> void g(const T (&...p)[V]);
793 // g({1, 2, 3}, {{}, {}});
794 // ... should deduce T = {int, size_t (from array bound)}.
795 Pack.New[0].wasDeducedFromArrayBound());
798 // Pick where we're going to put the merged pack.
799 DeducedTemplateArgument *Loc;
801 if (Pack.Outer->DeferredDeduction.isNull()) {
802 // Defer checking this pack until we have a complete pack to compare
804 Pack.Outer->DeferredDeduction = NewPack;
807 Loc = &Pack.Outer->DeferredDeduction;
809 Loc = &Deduced[Pack.Index];
812 // Check the new pack matches any previous value.
813 DeducedTemplateArgument OldPack = *Loc;
814 DeducedTemplateArgument Result =
815 checkDeducedTemplateArguments(S.Context, OldPack, NewPack);
817 // If we deferred a deduction of this pack, check that one now too.
818 if (!Result.isNull() && !Pack.DeferredDeduction.isNull()) {
820 NewPack = Pack.DeferredDeduction;
821 Result = checkDeducedTemplateArguments(S.Context, OldPack, NewPack);
824 if (Result.isNull()) {
826 makeTemplateParameter(TemplateParams->getParam(Pack.Index));
827 Info.FirstArg = OldPack;
828 Info.SecondArg = NewPack;
829 return Sema::TDK_Inconsistent;
835 return Sema::TDK_Success;
840 TemplateParameterList *TemplateParams;
841 SmallVectorImpl<DeducedTemplateArgument> &Deduced;
842 TemplateDeductionInfo &Info;
843 unsigned PackElements = 0;
844 bool IsPartiallyExpanded = false;
846 SmallVector<DeducedPack, 2> Packs;
850 /// \brief Deduce the template arguments by comparing the list of parameter
851 /// types to the list of argument types, as in the parameter-type-lists of
852 /// function types (C++ [temp.deduct.type]p10).
854 /// \param S The semantic analysis object within which we are deducing
856 /// \param TemplateParams The template parameters that we are deducing
858 /// \param Params The list of parameter types
860 /// \param NumParams The number of types in \c Params
862 /// \param Args The list of argument types
864 /// \param NumArgs The number of types in \c Args
866 /// \param Info information about the template argument deduction itself
868 /// \param Deduced the deduced template arguments
870 /// \param TDF bitwise OR of the TemplateDeductionFlags bits that describe
871 /// how template argument deduction is performed.
873 /// \param PartialOrdering If true, we are performing template argument
874 /// deduction for during partial ordering for a call
875 /// (C++0x [temp.deduct.partial]).
877 /// \returns the result of template argument deduction so far. Note that a
878 /// "success" result means that template argument deduction has not yet failed,
879 /// but it may still fail, later, for other reasons.
880 static Sema::TemplateDeductionResult
881 DeduceTemplateArguments(Sema &S,
882 TemplateParameterList *TemplateParams,
883 const QualType *Params, unsigned NumParams,
884 const QualType *Args, unsigned NumArgs,
885 TemplateDeductionInfo &Info,
886 SmallVectorImpl<DeducedTemplateArgument> &Deduced,
888 bool PartialOrdering = false) {
889 // Fast-path check to see if we have too many/too few arguments.
890 if (NumParams != NumArgs &&
891 !(NumParams && isa<PackExpansionType>(Params[NumParams - 1])) &&
892 !(NumArgs && isa<PackExpansionType>(Args[NumArgs - 1])))
893 return Sema::TDK_MiscellaneousDeductionFailure;
895 // C++0x [temp.deduct.type]p10:
896 // Similarly, if P has a form that contains (T), then each parameter type
897 // Pi of the respective parameter-type- list of P is compared with the
898 // corresponding parameter type Ai of the corresponding parameter-type-list
900 unsigned ArgIdx = 0, ParamIdx = 0;
901 for (; ParamIdx != NumParams; ++ParamIdx) {
902 // Check argument types.
903 const PackExpansionType *Expansion
904 = dyn_cast<PackExpansionType>(Params[ParamIdx]);
906 // Simple case: compare the parameter and argument types at this point.
908 // Make sure we have an argument.
909 if (ArgIdx >= NumArgs)
910 return Sema::TDK_MiscellaneousDeductionFailure;
912 if (isa<PackExpansionType>(Args[ArgIdx])) {
913 // C++0x [temp.deduct.type]p22:
914 // If the original function parameter associated with A is a function
915 // parameter pack and the function parameter associated with P is not
916 // a function parameter pack, then template argument deduction fails.
917 return Sema::TDK_MiscellaneousDeductionFailure;
920 if (Sema::TemplateDeductionResult Result
921 = DeduceTemplateArgumentsByTypeMatch(S, TemplateParams,
922 Params[ParamIdx], Args[ArgIdx],
931 // C++0x [temp.deduct.type]p5:
932 // The non-deduced contexts are:
933 // - A function parameter pack that does not occur at the end of the
934 // parameter-declaration-clause.
935 if (ParamIdx + 1 < NumParams)
936 return Sema::TDK_Success;
938 // C++0x [temp.deduct.type]p10:
939 // If the parameter-declaration corresponding to Pi is a function
940 // parameter pack, then the type of its declarator- id is compared with
941 // each remaining parameter type in the parameter-type-list of A. Each
942 // comparison deduces template arguments for subsequent positions in the
943 // template parameter packs expanded by the function parameter pack.
945 QualType Pattern = Expansion->getPattern();
946 PackDeductionScope PackScope(S, TemplateParams, Deduced, Info, Pattern);
948 for (; ArgIdx < NumArgs; ++ArgIdx) {
949 // Deduce template arguments from the pattern.
950 if (Sema::TemplateDeductionResult Result
951 = DeduceTemplateArgumentsByTypeMatch(S, TemplateParams, Pattern,
952 Args[ArgIdx], Info, Deduced,
953 TDF, PartialOrdering))
956 PackScope.nextPackElement();
959 // Build argument packs for each of the parameter packs expanded by this
961 if (auto Result = PackScope.finish())
965 // Make sure we don't have any extra arguments.
966 if (ArgIdx < NumArgs)
967 return Sema::TDK_MiscellaneousDeductionFailure;
969 return Sema::TDK_Success;
972 /// \brief Determine whether the parameter has qualifiers that are either
973 /// inconsistent with or a superset of the argument's qualifiers.
974 static bool hasInconsistentOrSupersetQualifiersOf(QualType ParamType,
976 Qualifiers ParamQs = ParamType.getQualifiers();
977 Qualifiers ArgQs = ArgType.getQualifiers();
979 if (ParamQs == ArgQs)
982 // Mismatched (but not missing) Objective-C GC attributes.
983 if (ParamQs.getObjCGCAttr() != ArgQs.getObjCGCAttr() &&
984 ParamQs.hasObjCGCAttr())
987 // Mismatched (but not missing) address spaces.
988 if (ParamQs.getAddressSpace() != ArgQs.getAddressSpace() &&
989 ParamQs.hasAddressSpace())
992 // Mismatched (but not missing) Objective-C lifetime qualifiers.
993 if (ParamQs.getObjCLifetime() != ArgQs.getObjCLifetime() &&
994 ParamQs.hasObjCLifetime())
997 // CVR qualifier superset.
998 return (ParamQs.getCVRQualifiers() != ArgQs.getCVRQualifiers()) &&
999 ((ParamQs.getCVRQualifiers() | ArgQs.getCVRQualifiers())
1000 == ParamQs.getCVRQualifiers());
1003 /// \brief Compare types for equality with respect to possibly compatible
1004 /// function types (noreturn adjustment, implicit calling conventions). If any
1005 /// of parameter and argument is not a function, just perform type comparison.
1007 /// \param Param the template parameter type.
1009 /// \param Arg the argument type.
1010 bool Sema::isSameOrCompatibleFunctionType(CanQualType Param,
1012 const FunctionType *ParamFunction = Param->getAs<FunctionType>(),
1013 *ArgFunction = Arg->getAs<FunctionType>();
1015 // Just compare if not functions.
1016 if (!ParamFunction || !ArgFunction)
1017 return Param == Arg;
1019 // Noreturn and noexcept adjustment.
1020 QualType AdjustedParam;
1021 if (IsFunctionConversion(Param, Arg, AdjustedParam))
1022 return Arg == Context.getCanonicalType(AdjustedParam);
1024 // FIXME: Compatible calling conventions.
1026 return Param == Arg;
1029 /// Get the index of the first template parameter that was originally from the
1030 /// innermost template-parameter-list. This is 0 except when we concatenate
1031 /// the template parameter lists of a class template and a constructor template
1032 /// when forming an implicit deduction guide.
1033 static unsigned getFirstInnerIndex(FunctionTemplateDecl *FTD) {
1034 auto *Guide = dyn_cast<CXXDeductionGuideDecl>(FTD->getTemplatedDecl());
1035 if (!Guide || !Guide->isImplicit())
1037 return Guide->getDeducedTemplate()->getTemplateParameters()->size();
1040 /// Determine whether a type denotes a forwarding reference.
1041 static bool isForwardingReference(QualType Param, unsigned FirstInnerIndex) {
1042 // C++1z [temp.deduct.call]p3:
1043 // A forwarding reference is an rvalue reference to a cv-unqualified
1044 // template parameter that does not represent a template parameter of a
1046 if (auto *ParamRef = Param->getAs<RValueReferenceType>()) {
1047 if (ParamRef->getPointeeType().getQualifiers())
1049 auto *TypeParm = ParamRef->getPointeeType()->getAs<TemplateTypeParmType>();
1050 return TypeParm && TypeParm->getIndex() >= FirstInnerIndex;
1055 /// \brief Deduce the template arguments by comparing the parameter type and
1056 /// the argument type (C++ [temp.deduct.type]).
1058 /// \param S the semantic analysis object within which we are deducing
1060 /// \param TemplateParams the template parameters that we are deducing
1062 /// \param ParamIn the parameter type
1064 /// \param ArgIn the argument type
1066 /// \param Info information about the template argument deduction itself
1068 /// \param Deduced the deduced template arguments
1070 /// \param TDF bitwise OR of the TemplateDeductionFlags bits that describe
1071 /// how template argument deduction is performed.
1073 /// \param PartialOrdering Whether we're performing template argument deduction
1074 /// in the context of partial ordering (C++0x [temp.deduct.partial]).
1076 /// \returns the result of template argument deduction so far. Note that a
1077 /// "success" result means that template argument deduction has not yet failed,
1078 /// but it may still fail, later, for other reasons.
1079 static Sema::TemplateDeductionResult
1080 DeduceTemplateArgumentsByTypeMatch(Sema &S,
1081 TemplateParameterList *TemplateParams,
1082 QualType ParamIn, QualType ArgIn,
1083 TemplateDeductionInfo &Info,
1084 SmallVectorImpl<DeducedTemplateArgument> &Deduced,
1086 bool PartialOrdering,
1087 bool DeducedFromArrayBound) {
1088 // We only want to look at the canonical types, since typedefs and
1089 // sugar are not part of template argument deduction.
1090 QualType Param = S.Context.getCanonicalType(ParamIn);
1091 QualType Arg = S.Context.getCanonicalType(ArgIn);
1093 // If the argument type is a pack expansion, look at its pattern.
1094 // This isn't explicitly called out
1095 if (const PackExpansionType *ArgExpansion
1096 = dyn_cast<PackExpansionType>(Arg))
1097 Arg = ArgExpansion->getPattern();
1099 if (PartialOrdering) {
1100 // C++11 [temp.deduct.partial]p5:
1101 // Before the partial ordering is done, certain transformations are
1102 // performed on the types used for partial ordering:
1103 // - If P is a reference type, P is replaced by the type referred to.
1104 const ReferenceType *ParamRef = Param->getAs<ReferenceType>();
1106 Param = ParamRef->getPointeeType();
1108 // - If A is a reference type, A is replaced by the type referred to.
1109 const ReferenceType *ArgRef = Arg->getAs<ReferenceType>();
1111 Arg = ArgRef->getPointeeType();
1113 if (ParamRef && ArgRef && S.Context.hasSameUnqualifiedType(Param, Arg)) {
1114 // C++11 [temp.deduct.partial]p9:
1115 // If, for a given type, deduction succeeds in both directions (i.e.,
1116 // the types are identical after the transformations above) and both
1117 // P and A were reference types [...]:
1118 // - if [one type] was an lvalue reference and [the other type] was
1119 // not, [the other type] is not considered to be at least as
1120 // specialized as [the first type]
1121 // - if [one type] is more cv-qualified than [the other type],
1122 // [the other type] is not considered to be at least as specialized
1123 // as [the first type]
1124 // Objective-C ARC adds:
1125 // - [one type] has non-trivial lifetime, [the other type] has
1126 // __unsafe_unretained lifetime, and the types are otherwise
1129 // A is "considered to be at least as specialized" as P iff deduction
1130 // succeeds, so we model this as a deduction failure. Note that
1131 // [the first type] is P and [the other type] is A here; the standard
1132 // gets this backwards.
1133 Qualifiers ParamQuals = Param.getQualifiers();
1134 Qualifiers ArgQuals = Arg.getQualifiers();
1135 if ((ParamRef->isLValueReferenceType() &&
1136 !ArgRef->isLValueReferenceType()) ||
1137 ParamQuals.isStrictSupersetOf(ArgQuals) ||
1138 (ParamQuals.hasNonTrivialObjCLifetime() &&
1139 ArgQuals.getObjCLifetime() == Qualifiers::OCL_ExplicitNone &&
1140 ParamQuals.withoutObjCLifetime() ==
1141 ArgQuals.withoutObjCLifetime())) {
1142 Info.FirstArg = TemplateArgument(ParamIn);
1143 Info.SecondArg = TemplateArgument(ArgIn);
1144 return Sema::TDK_NonDeducedMismatch;
1148 // C++11 [temp.deduct.partial]p7:
1149 // Remove any top-level cv-qualifiers:
1150 // - If P is a cv-qualified type, P is replaced by the cv-unqualified
1152 Param = Param.getUnqualifiedType();
1153 // - If A is a cv-qualified type, A is replaced by the cv-unqualified
1155 Arg = Arg.getUnqualifiedType();
1157 // C++0x [temp.deduct.call]p4 bullet 1:
1158 // - If the original P is a reference type, the deduced A (i.e., the type
1159 // referred to by the reference) can be more cv-qualified than the
1161 if (TDF & TDF_ParamWithReferenceType) {
1163 QualType UnqualParam = S.Context.getUnqualifiedArrayType(Param, Quals);
1164 Quals.setCVRQualifiers(Quals.getCVRQualifiers() &
1165 Arg.getCVRQualifiers());
1166 Param = S.Context.getQualifiedType(UnqualParam, Quals);
1169 if ((TDF & TDF_TopLevelParameterTypeList) && !Param->isFunctionType()) {
1170 // C++0x [temp.deduct.type]p10:
1171 // If P and A are function types that originated from deduction when
1172 // taking the address of a function template (14.8.2.2) or when deducing
1173 // template arguments from a function declaration (14.8.2.6) and Pi and
1174 // Ai are parameters of the top-level parameter-type-list of P and A,
1175 // respectively, Pi is adjusted if it is a forwarding reference and Ai
1176 // is an lvalue reference, in
1177 // which case the type of Pi is changed to be the template parameter
1178 // type (i.e., T&& is changed to simply T). [ Note: As a result, when
1179 // Pi is T&& and Ai is X&, the adjusted Pi will be T, causing T to be
1180 // deduced as X&. - end note ]
1181 TDF &= ~TDF_TopLevelParameterTypeList;
1182 if (isForwardingReference(Param, 0) && Arg->isLValueReferenceType())
1183 Param = Param->getPointeeType();
1187 // C++ [temp.deduct.type]p9:
1188 // A template type argument T, a template template argument TT or a
1189 // template non-type argument i can be deduced if P and A have one of
1190 // the following forms:
1194 if (const TemplateTypeParmType *TemplateTypeParm
1195 = Param->getAs<TemplateTypeParmType>()) {
1196 // Just skip any attempts to deduce from a placeholder type or a parameter
1197 // at a different depth.
1198 if (Arg->isPlaceholderType() ||
1199 Info.getDeducedDepth() != TemplateTypeParm->getDepth())
1200 return Sema::TDK_Success;
1202 unsigned Index = TemplateTypeParm->getIndex();
1203 bool RecanonicalizeArg = false;
1205 // If the argument type is an array type, move the qualifiers up to the
1206 // top level, so they can be matched with the qualifiers on the parameter.
1207 if (isa<ArrayType>(Arg)) {
1209 Arg = S.Context.getUnqualifiedArrayType(Arg, Quals);
1211 Arg = S.Context.getQualifiedType(Arg, Quals);
1212 RecanonicalizeArg = true;
1216 // The argument type can not be less qualified than the parameter
1218 if (!(TDF & TDF_IgnoreQualifiers) &&
1219 hasInconsistentOrSupersetQualifiersOf(Param, Arg)) {
1220 Info.Param = cast<TemplateTypeParmDecl>(TemplateParams->getParam(Index));
1221 Info.FirstArg = TemplateArgument(Param);
1222 Info.SecondArg = TemplateArgument(Arg);
1223 return Sema::TDK_Underqualified;
1226 assert(TemplateTypeParm->getDepth() == Info.getDeducedDepth() &&
1227 "saw template type parameter with wrong depth");
1228 assert(Arg != S.Context.OverloadTy && "Unresolved overloaded function");
1229 QualType DeducedType = Arg;
1231 // Remove any qualifiers on the parameter from the deduced type.
1232 // We checked the qualifiers for consistency above.
1233 Qualifiers DeducedQs = DeducedType.getQualifiers();
1234 Qualifiers ParamQs = Param.getQualifiers();
1235 DeducedQs.removeCVRQualifiers(ParamQs.getCVRQualifiers());
1236 if (ParamQs.hasObjCGCAttr())
1237 DeducedQs.removeObjCGCAttr();
1238 if (ParamQs.hasAddressSpace())
1239 DeducedQs.removeAddressSpace();
1240 if (ParamQs.hasObjCLifetime())
1241 DeducedQs.removeObjCLifetime();
1244 // If template deduction would produce a lifetime qualifier on a type
1245 // that is not a lifetime type, template argument deduction fails.
1246 if (ParamQs.hasObjCLifetime() && !DeducedType->isObjCLifetimeType() &&
1247 !DeducedType->isDependentType()) {
1248 Info.Param = cast<TemplateTypeParmDecl>(TemplateParams->getParam(Index));
1249 Info.FirstArg = TemplateArgument(Param);
1250 Info.SecondArg = TemplateArgument(Arg);
1251 return Sema::TDK_Underqualified;
1255 // If template deduction would produce an argument type with lifetime type
1256 // but no lifetime qualifier, the __strong lifetime qualifier is inferred.
1257 if (S.getLangOpts().ObjCAutoRefCount &&
1258 DeducedType->isObjCLifetimeType() &&
1259 !DeducedQs.hasObjCLifetime())
1260 DeducedQs.setObjCLifetime(Qualifiers::OCL_Strong);
1262 DeducedType = S.Context.getQualifiedType(DeducedType.getUnqualifiedType(),
1265 if (RecanonicalizeArg)
1266 DeducedType = S.Context.getCanonicalType(DeducedType);
1268 DeducedTemplateArgument NewDeduced(DeducedType, DeducedFromArrayBound);
1269 DeducedTemplateArgument Result = checkDeducedTemplateArguments(S.Context,
1272 if (Result.isNull()) {
1273 Info.Param = cast<TemplateTypeParmDecl>(TemplateParams->getParam(Index));
1274 Info.FirstArg = Deduced[Index];
1275 Info.SecondArg = NewDeduced;
1276 return Sema::TDK_Inconsistent;
1279 Deduced[Index] = Result;
1280 return Sema::TDK_Success;
1283 // Set up the template argument deduction information for a failure.
1284 Info.FirstArg = TemplateArgument(ParamIn);
1285 Info.SecondArg = TemplateArgument(ArgIn);
1287 // If the parameter is an already-substituted template parameter
1288 // pack, do nothing: we don't know which of its arguments to look
1289 // at, so we have to wait until all of the parameter packs in this
1290 // expansion have arguments.
1291 if (isa<SubstTemplateTypeParmPackType>(Param))
1292 return Sema::TDK_Success;
1294 // Check the cv-qualifiers on the parameter and argument types.
1295 CanQualType CanParam = S.Context.getCanonicalType(Param);
1296 CanQualType CanArg = S.Context.getCanonicalType(Arg);
1297 if (!(TDF & TDF_IgnoreQualifiers)) {
1298 if (TDF & TDF_ParamWithReferenceType) {
1299 if (hasInconsistentOrSupersetQualifiersOf(Param, Arg))
1300 return Sema::TDK_NonDeducedMismatch;
1301 } else if (!IsPossiblyOpaquelyQualifiedType(Param)) {
1302 if (Param.getCVRQualifiers() != Arg.getCVRQualifiers())
1303 return Sema::TDK_NonDeducedMismatch;
1306 // If the parameter type is not dependent, there is nothing to deduce.
1307 if (!Param->isDependentType()) {
1308 if (!(TDF & TDF_SkipNonDependent)) {
1309 bool NonDeduced = (TDF & TDF_InOverloadResolution)?
1310 !S.isSameOrCompatibleFunctionType(CanParam, CanArg) :
1313 return Sema::TDK_NonDeducedMismatch;
1316 return Sema::TDK_Success;
1318 } else if (!Param->isDependentType()) {
1319 CanQualType ParamUnqualType = CanParam.getUnqualifiedType(),
1320 ArgUnqualType = CanArg.getUnqualifiedType();
1321 bool Success = (TDF & TDF_InOverloadResolution)?
1322 S.isSameOrCompatibleFunctionType(ParamUnqualType,
1324 ParamUnqualType == ArgUnqualType;
1326 return Sema::TDK_Success;
1329 switch (Param->getTypeClass()) {
1330 // Non-canonical types cannot appear here.
1331 #define NON_CANONICAL_TYPE(Class, Base) \
1332 case Type::Class: llvm_unreachable("deducing non-canonical type: " #Class);
1333 #define TYPE(Class, Base)
1334 #include "clang/AST/TypeNodes.def"
1336 case Type::TemplateTypeParm:
1337 case Type::SubstTemplateTypeParmPack:
1338 llvm_unreachable("Type nodes handled above");
1340 // These types cannot be dependent, so simply check whether the types are
1343 case Type::VariableArray:
1345 case Type::FunctionNoProto:
1348 case Type::ObjCObject:
1349 case Type::ObjCInterface:
1350 case Type::ObjCObjectPointer: {
1351 if (TDF & TDF_SkipNonDependent)
1352 return Sema::TDK_Success;
1354 if (TDF & TDF_IgnoreQualifiers) {
1355 Param = Param.getUnqualifiedType();
1356 Arg = Arg.getUnqualifiedType();
1359 return Param == Arg? Sema::TDK_Success : Sema::TDK_NonDeducedMismatch;
1362 // _Complex T [placeholder extension]
1364 if (const ComplexType *ComplexArg = Arg->getAs<ComplexType>())
1365 return DeduceTemplateArgumentsByTypeMatch(S, TemplateParams,
1366 cast<ComplexType>(Param)->getElementType(),
1367 ComplexArg->getElementType(),
1368 Info, Deduced, TDF);
1370 return Sema::TDK_NonDeducedMismatch;
1372 // _Atomic T [extension]
1374 if (const AtomicType *AtomicArg = Arg->getAs<AtomicType>())
1375 return DeduceTemplateArgumentsByTypeMatch(S, TemplateParams,
1376 cast<AtomicType>(Param)->getValueType(),
1377 AtomicArg->getValueType(),
1378 Info, Deduced, TDF);
1380 return Sema::TDK_NonDeducedMismatch;
1383 case Type::Pointer: {
1384 QualType PointeeType;
1385 if (const PointerType *PointerArg = Arg->getAs<PointerType>()) {
1386 PointeeType = PointerArg->getPointeeType();
1387 } else if (const ObjCObjectPointerType *PointerArg
1388 = Arg->getAs<ObjCObjectPointerType>()) {
1389 PointeeType = PointerArg->getPointeeType();
1391 return Sema::TDK_NonDeducedMismatch;
1394 unsigned SubTDF = TDF & (TDF_IgnoreQualifiers | TDF_DerivedClass);
1395 return DeduceTemplateArgumentsByTypeMatch(S, TemplateParams,
1396 cast<PointerType>(Param)->getPointeeType(),
1398 Info, Deduced, SubTDF);
1402 case Type::LValueReference: {
1403 const LValueReferenceType *ReferenceArg =
1404 Arg->getAs<LValueReferenceType>();
1406 return Sema::TDK_NonDeducedMismatch;
1408 return DeduceTemplateArgumentsByTypeMatch(S, TemplateParams,
1409 cast<LValueReferenceType>(Param)->getPointeeType(),
1410 ReferenceArg->getPointeeType(), Info, Deduced, 0);
1414 case Type::RValueReference: {
1415 const RValueReferenceType *ReferenceArg =
1416 Arg->getAs<RValueReferenceType>();
1418 return Sema::TDK_NonDeducedMismatch;
1420 return DeduceTemplateArgumentsByTypeMatch(S, TemplateParams,
1421 cast<RValueReferenceType>(Param)->getPointeeType(),
1422 ReferenceArg->getPointeeType(),
1426 // T [] (implied, but not stated explicitly)
1427 case Type::IncompleteArray: {
1428 const IncompleteArrayType *IncompleteArrayArg =
1429 S.Context.getAsIncompleteArrayType(Arg);
1430 if (!IncompleteArrayArg)
1431 return Sema::TDK_NonDeducedMismatch;
1433 unsigned SubTDF = TDF & TDF_IgnoreQualifiers;
1434 return DeduceTemplateArgumentsByTypeMatch(S, TemplateParams,
1435 S.Context.getAsIncompleteArrayType(Param)->getElementType(),
1436 IncompleteArrayArg->getElementType(),
1437 Info, Deduced, SubTDF);
1440 // T [integer-constant]
1441 case Type::ConstantArray: {
1442 const ConstantArrayType *ConstantArrayArg =
1443 S.Context.getAsConstantArrayType(Arg);
1444 if (!ConstantArrayArg)
1445 return Sema::TDK_NonDeducedMismatch;
1447 const ConstantArrayType *ConstantArrayParm =
1448 S.Context.getAsConstantArrayType(Param);
1449 if (ConstantArrayArg->getSize() != ConstantArrayParm->getSize())
1450 return Sema::TDK_NonDeducedMismatch;
1452 unsigned SubTDF = TDF & TDF_IgnoreQualifiers;
1453 return DeduceTemplateArgumentsByTypeMatch(S, TemplateParams,
1454 ConstantArrayParm->getElementType(),
1455 ConstantArrayArg->getElementType(),
1456 Info, Deduced, SubTDF);
1460 case Type::DependentSizedArray: {
1461 const ArrayType *ArrayArg = S.Context.getAsArrayType(Arg);
1463 return Sema::TDK_NonDeducedMismatch;
1465 unsigned SubTDF = TDF & TDF_IgnoreQualifiers;
1467 // Check the element type of the arrays
1468 const DependentSizedArrayType *DependentArrayParm
1469 = S.Context.getAsDependentSizedArrayType(Param);
1470 if (Sema::TemplateDeductionResult Result
1471 = DeduceTemplateArgumentsByTypeMatch(S, TemplateParams,
1472 DependentArrayParm->getElementType(),
1473 ArrayArg->getElementType(),
1474 Info, Deduced, SubTDF))
1477 // Determine the array bound is something we can deduce.
1478 NonTypeTemplateParmDecl *NTTP
1479 = getDeducedParameterFromExpr(Info, DependentArrayParm->getSizeExpr());
1481 return Sema::TDK_Success;
1483 // We can perform template argument deduction for the given non-type
1484 // template parameter.
1485 assert(NTTP->getDepth() == Info.getDeducedDepth() &&
1486 "saw non-type template parameter with wrong depth");
1487 if (const ConstantArrayType *ConstantArrayArg
1488 = dyn_cast<ConstantArrayType>(ArrayArg)) {
1489 llvm::APSInt Size(ConstantArrayArg->getSize());
1490 return DeduceNonTypeTemplateArgument(S, TemplateParams, NTTP, Size,
1491 S.Context.getSizeType(),
1492 /*ArrayBound=*/true,
1495 if (const DependentSizedArrayType *DependentArrayArg
1496 = dyn_cast<DependentSizedArrayType>(ArrayArg))
1497 if (DependentArrayArg->getSizeExpr())
1498 return DeduceNonTypeTemplateArgument(S, TemplateParams, NTTP,
1499 DependentArrayArg->getSizeExpr(),
1502 // Incomplete type does not match a dependently-sized array type
1503 return Sema::TDK_NonDeducedMismatch;
1509 case Type::FunctionProto: {
1510 unsigned SubTDF = TDF & TDF_TopLevelParameterTypeList;
1511 const FunctionProtoType *FunctionProtoArg =
1512 dyn_cast<FunctionProtoType>(Arg);
1513 if (!FunctionProtoArg)
1514 return Sema::TDK_NonDeducedMismatch;
1516 const FunctionProtoType *FunctionProtoParam =
1517 cast<FunctionProtoType>(Param);
1519 if (FunctionProtoParam->getTypeQuals()
1520 != FunctionProtoArg->getTypeQuals() ||
1521 FunctionProtoParam->getRefQualifier()
1522 != FunctionProtoArg->getRefQualifier() ||
1523 FunctionProtoParam->isVariadic() != FunctionProtoArg->isVariadic())
1524 return Sema::TDK_NonDeducedMismatch;
1526 // Check return types.
1527 if (Sema::TemplateDeductionResult Result =
1528 DeduceTemplateArgumentsByTypeMatch(
1529 S, TemplateParams, FunctionProtoParam->getReturnType(),
1530 FunctionProtoArg->getReturnType(), Info, Deduced, 0))
1533 return DeduceTemplateArguments(
1534 S, TemplateParams, FunctionProtoParam->param_type_begin(),
1535 FunctionProtoParam->getNumParams(),
1536 FunctionProtoArg->param_type_begin(),
1537 FunctionProtoArg->getNumParams(), Info, Deduced, SubTDF);
1540 case Type::InjectedClassName: {
1541 // Treat a template's injected-class-name as if the template
1542 // specialization type had been used.
1543 Param = cast<InjectedClassNameType>(Param)
1544 ->getInjectedSpecializationType();
1545 assert(isa<TemplateSpecializationType>(Param) &&
1546 "injected class name is not a template specialization type");
1550 // template-name<T> (where template-name refers to a class template)
1555 case Type::TemplateSpecialization: {
1556 const TemplateSpecializationType *SpecParam =
1557 cast<TemplateSpecializationType>(Param);
1559 // When Arg cannot be a derived class, we can just try to deduce template
1560 // arguments from the template-id.
1561 const RecordType *RecordT = Arg->getAs<RecordType>();
1562 if (!(TDF & TDF_DerivedClass) || !RecordT)
1563 return DeduceTemplateArguments(S, TemplateParams, SpecParam, Arg, Info,
1566 SmallVector<DeducedTemplateArgument, 8> DeducedOrig(Deduced.begin(),
1569 Sema::TemplateDeductionResult Result = DeduceTemplateArguments(
1570 S, TemplateParams, SpecParam, Arg, Info, Deduced);
1572 if (Result == Sema::TDK_Success)
1575 // We cannot inspect base classes as part of deduction when the type
1576 // is incomplete, so either instantiate any templates necessary to
1577 // complete the type, or skip over it if it cannot be completed.
1578 if (!S.isCompleteType(Info.getLocation(), Arg))
1581 // C++14 [temp.deduct.call] p4b3:
1582 // If P is a class and P has the form simple-template-id, then the
1583 // transformed A can be a derived class of the deduced A. Likewise if
1584 // P is a pointer to a class of the form simple-template-id, the
1585 // transformed A can be a pointer to a derived class pointed to by the
1588 // These alternatives are considered only if type deduction would
1589 // otherwise fail. If they yield more than one possible deduced A, the
1590 // type deduction fails.
1592 // Reset the incorrectly deduced argument from above.
1593 Deduced = DeducedOrig;
1595 // Use data recursion to crawl through the list of base classes.
1596 // Visited contains the set of nodes we have already visited, while
1597 // ToVisit is our stack of records that we still need to visit.
1598 llvm::SmallPtrSet<const RecordType *, 8> Visited;
1599 SmallVector<const RecordType *, 8> ToVisit;
1600 ToVisit.push_back(RecordT);
1601 bool Successful = false;
1602 SmallVector<DeducedTemplateArgument, 8> SuccessfulDeduced;
1603 while (!ToVisit.empty()) {
1604 // Retrieve the next class in the inheritance hierarchy.
1605 const RecordType *NextT = ToVisit.pop_back_val();
1607 // If we have already seen this type, skip it.
1608 if (!Visited.insert(NextT).second)
1611 // If this is a base class, try to perform template argument
1612 // deduction from it.
1613 if (NextT != RecordT) {
1614 TemplateDeductionInfo BaseInfo(Info.getLocation());
1615 Sema::TemplateDeductionResult BaseResult =
1616 DeduceTemplateArguments(S, TemplateParams, SpecParam,
1617 QualType(NextT, 0), BaseInfo, Deduced);
1619 // If template argument deduction for this base was successful,
1620 // note that we had some success. Otherwise, ignore any deductions
1621 // from this base class.
1622 if (BaseResult == Sema::TDK_Success) {
1623 // If we've already seen some success, then deduction fails due to
1624 // an ambiguity (temp.deduct.call p5).
1626 return Sema::TDK_MiscellaneousDeductionFailure;
1629 std::swap(SuccessfulDeduced, Deduced);
1631 Info.Param = BaseInfo.Param;
1632 Info.FirstArg = BaseInfo.FirstArg;
1633 Info.SecondArg = BaseInfo.SecondArg;
1636 Deduced = DeducedOrig;
1639 // Visit base classes
1640 CXXRecordDecl *Next = cast<CXXRecordDecl>(NextT->getDecl());
1641 for (const auto &Base : Next->bases()) {
1642 assert(Base.getType()->isRecordType() &&
1643 "Base class that isn't a record?");
1644 ToVisit.push_back(Base.getType()->getAs<RecordType>());
1649 std::swap(SuccessfulDeduced, Deduced);
1650 return Sema::TDK_Success;
1660 // type (type::*)(T)
1665 case Type::MemberPointer: {
1666 const MemberPointerType *MemPtrParam = cast<MemberPointerType>(Param);
1667 const MemberPointerType *MemPtrArg = dyn_cast<MemberPointerType>(Arg);
1669 return Sema::TDK_NonDeducedMismatch;
1671 QualType ParamPointeeType = MemPtrParam->getPointeeType();
1672 if (ParamPointeeType->isFunctionType())
1673 S.adjustMemberFunctionCC(ParamPointeeType, /*IsStatic=*/true,
1674 /*IsCtorOrDtor=*/false, Info.getLocation());
1675 QualType ArgPointeeType = MemPtrArg->getPointeeType();
1676 if (ArgPointeeType->isFunctionType())
1677 S.adjustMemberFunctionCC(ArgPointeeType, /*IsStatic=*/true,
1678 /*IsCtorOrDtor=*/false, Info.getLocation());
1680 if (Sema::TemplateDeductionResult Result
1681 = DeduceTemplateArgumentsByTypeMatch(S, TemplateParams,
1685 TDF & TDF_IgnoreQualifiers))
1688 return DeduceTemplateArgumentsByTypeMatch(S, TemplateParams,
1689 QualType(MemPtrParam->getClass(), 0),
1690 QualType(MemPtrArg->getClass(), 0),
1692 TDF & TDF_IgnoreQualifiers);
1695 // (clang extension)
1700 case Type::BlockPointer: {
1701 const BlockPointerType *BlockPtrParam = cast<BlockPointerType>(Param);
1702 const BlockPointerType *BlockPtrArg = dyn_cast<BlockPointerType>(Arg);
1705 return Sema::TDK_NonDeducedMismatch;
1707 return DeduceTemplateArgumentsByTypeMatch(S, TemplateParams,
1708 BlockPtrParam->getPointeeType(),
1709 BlockPtrArg->getPointeeType(),
1713 // (clang extension)
1715 // T __attribute__(((ext_vector_type(<integral constant>))))
1716 case Type::ExtVector: {
1717 const ExtVectorType *VectorParam = cast<ExtVectorType>(Param);
1718 if (const ExtVectorType *VectorArg = dyn_cast<ExtVectorType>(Arg)) {
1719 // Make sure that the vectors have the same number of elements.
1720 if (VectorParam->getNumElements() != VectorArg->getNumElements())
1721 return Sema::TDK_NonDeducedMismatch;
1723 // Perform deduction on the element types.
1724 return DeduceTemplateArgumentsByTypeMatch(S, TemplateParams,
1725 VectorParam->getElementType(),
1726 VectorArg->getElementType(),
1727 Info, Deduced, TDF);
1730 if (const DependentSizedExtVectorType *VectorArg
1731 = dyn_cast<DependentSizedExtVectorType>(Arg)) {
1732 // We can't check the number of elements, since the argument has a
1733 // dependent number of elements. This can only occur during partial
1736 // Perform deduction on the element types.
1737 return DeduceTemplateArgumentsByTypeMatch(S, TemplateParams,
1738 VectorParam->getElementType(),
1739 VectorArg->getElementType(),
1740 Info, Deduced, TDF);
1743 return Sema::TDK_NonDeducedMismatch;
1746 // (clang extension)
1748 // T __attribute__(((ext_vector_type(N))))
1749 case Type::DependentSizedExtVector: {
1750 const DependentSizedExtVectorType *VectorParam
1751 = cast<DependentSizedExtVectorType>(Param);
1753 if (const ExtVectorType *VectorArg = dyn_cast<ExtVectorType>(Arg)) {
1754 // Perform deduction on the element types.
1755 if (Sema::TemplateDeductionResult Result
1756 = DeduceTemplateArgumentsByTypeMatch(S, TemplateParams,
1757 VectorParam->getElementType(),
1758 VectorArg->getElementType(),
1759 Info, Deduced, TDF))
1762 // Perform deduction on the vector size, if we can.
1763 NonTypeTemplateParmDecl *NTTP
1764 = getDeducedParameterFromExpr(Info, VectorParam->getSizeExpr());
1766 return Sema::TDK_Success;
1768 llvm::APSInt ArgSize(S.Context.getTypeSize(S.Context.IntTy), false);
1769 ArgSize = VectorArg->getNumElements();
1770 // Note that we use the "array bound" rules here; just like in that
1771 // case, we don't have any particular type for the vector size, but
1772 // we can provide one if necessary.
1773 return DeduceNonTypeTemplateArgument(S, TemplateParams, NTTP, ArgSize,
1774 S.Context.IntTy, true, Info,
1778 if (const DependentSizedExtVectorType *VectorArg
1779 = dyn_cast<DependentSizedExtVectorType>(Arg)) {
1780 // Perform deduction on the element types.
1781 if (Sema::TemplateDeductionResult Result
1782 = DeduceTemplateArgumentsByTypeMatch(S, TemplateParams,
1783 VectorParam->getElementType(),
1784 VectorArg->getElementType(),
1785 Info, Deduced, TDF))
1788 // Perform deduction on the vector size, if we can.
1789 NonTypeTemplateParmDecl *NTTP
1790 = getDeducedParameterFromExpr(Info, VectorParam->getSizeExpr());
1792 return Sema::TDK_Success;
1794 return DeduceNonTypeTemplateArgument(S, TemplateParams, NTTP,
1795 VectorArg->getSizeExpr(),
1799 return Sema::TDK_NonDeducedMismatch;
1802 case Type::TypeOfExpr:
1804 case Type::DependentName:
1805 case Type::UnresolvedUsing:
1806 case Type::Decltype:
1807 case Type::UnaryTransform:
1809 case Type::DeducedTemplateSpecialization:
1810 case Type::DependentTemplateSpecialization:
1811 case Type::PackExpansion:
1813 // No template argument deduction for these types
1814 return Sema::TDK_Success;
1817 llvm_unreachable("Invalid Type Class!");
1820 static Sema::TemplateDeductionResult
1821 DeduceTemplateArguments(Sema &S,
1822 TemplateParameterList *TemplateParams,
1823 const TemplateArgument &Param,
1824 TemplateArgument Arg,
1825 TemplateDeductionInfo &Info,
1826 SmallVectorImpl<DeducedTemplateArgument> &Deduced) {
1827 // If the template argument is a pack expansion, perform template argument
1828 // deduction against the pattern of that expansion. This only occurs during
1829 // partial ordering.
1830 if (Arg.isPackExpansion())
1831 Arg = Arg.getPackExpansionPattern();
1833 switch (Param.getKind()) {
1834 case TemplateArgument::Null:
1835 llvm_unreachable("Null template argument in parameter list");
1837 case TemplateArgument::Type:
1838 if (Arg.getKind() == TemplateArgument::Type)
1839 return DeduceTemplateArgumentsByTypeMatch(S, TemplateParams,
1843 Info.FirstArg = Param;
1844 Info.SecondArg = Arg;
1845 return Sema::TDK_NonDeducedMismatch;
1847 case TemplateArgument::Template:
1848 if (Arg.getKind() == TemplateArgument::Template)
1849 return DeduceTemplateArguments(S, TemplateParams,
1850 Param.getAsTemplate(),
1851 Arg.getAsTemplate(), Info, Deduced);
1852 Info.FirstArg = Param;
1853 Info.SecondArg = Arg;
1854 return Sema::TDK_NonDeducedMismatch;
1856 case TemplateArgument::TemplateExpansion:
1857 llvm_unreachable("caller should handle pack expansions");
1859 case TemplateArgument::Declaration:
1860 if (Arg.getKind() == TemplateArgument::Declaration &&
1861 isSameDeclaration(Param.getAsDecl(), Arg.getAsDecl()))
1862 return Sema::TDK_Success;
1864 Info.FirstArg = Param;
1865 Info.SecondArg = Arg;
1866 return Sema::TDK_NonDeducedMismatch;
1868 case TemplateArgument::NullPtr:
1869 if (Arg.getKind() == TemplateArgument::NullPtr &&
1870 S.Context.hasSameType(Param.getNullPtrType(), Arg.getNullPtrType()))
1871 return Sema::TDK_Success;
1873 Info.FirstArg = Param;
1874 Info.SecondArg = Arg;
1875 return Sema::TDK_NonDeducedMismatch;
1877 case TemplateArgument::Integral:
1878 if (Arg.getKind() == TemplateArgument::Integral) {
1879 if (hasSameExtendedValue(Param.getAsIntegral(), Arg.getAsIntegral()))
1880 return Sema::TDK_Success;
1882 Info.FirstArg = Param;
1883 Info.SecondArg = Arg;
1884 return Sema::TDK_NonDeducedMismatch;
1887 if (Arg.getKind() == TemplateArgument::Expression) {
1888 Info.FirstArg = Param;
1889 Info.SecondArg = Arg;
1890 return Sema::TDK_NonDeducedMismatch;
1893 Info.FirstArg = Param;
1894 Info.SecondArg = Arg;
1895 return Sema::TDK_NonDeducedMismatch;
1897 case TemplateArgument::Expression: {
1898 if (NonTypeTemplateParmDecl *NTTP
1899 = getDeducedParameterFromExpr(Info, Param.getAsExpr())) {
1900 if (Arg.getKind() == TemplateArgument::Integral)
1901 return DeduceNonTypeTemplateArgument(S, TemplateParams, NTTP,
1902 Arg.getAsIntegral(),
1903 Arg.getIntegralType(),
1904 /*ArrayBound=*/false,
1906 if (Arg.getKind() == TemplateArgument::NullPtr)
1907 return DeduceNullPtrTemplateArgument(S, TemplateParams, NTTP,
1908 Arg.getNullPtrType(),
1910 if (Arg.getKind() == TemplateArgument::Expression)
1911 return DeduceNonTypeTemplateArgument(S, TemplateParams, NTTP,
1912 Arg.getAsExpr(), Info, Deduced);
1913 if (Arg.getKind() == TemplateArgument::Declaration)
1914 return DeduceNonTypeTemplateArgument(S, TemplateParams, NTTP,
1916 Arg.getParamTypeForDecl(),
1919 Info.FirstArg = Param;
1920 Info.SecondArg = Arg;
1921 return Sema::TDK_NonDeducedMismatch;
1924 // Can't deduce anything, but that's okay.
1925 return Sema::TDK_Success;
1927 case TemplateArgument::Pack:
1928 llvm_unreachable("Argument packs should be expanded by the caller!");
1931 llvm_unreachable("Invalid TemplateArgument Kind!");
1934 /// \brief Determine whether there is a template argument to be used for
1937 /// This routine "expands" argument packs in-place, overriding its input
1938 /// parameters so that \c Args[ArgIdx] will be the available template argument.
1940 /// \returns true if there is another template argument (which will be at
1941 /// \c Args[ArgIdx]), false otherwise.
1942 static bool hasTemplateArgumentForDeduction(ArrayRef<TemplateArgument> &Args,
1944 if (ArgIdx == Args.size())
1947 const TemplateArgument &Arg = Args[ArgIdx];
1948 if (Arg.getKind() != TemplateArgument::Pack)
1951 assert(ArgIdx == Args.size() - 1 && "Pack not at the end of argument list?");
1952 Args = Arg.pack_elements();
1954 return ArgIdx < Args.size();
1957 /// \brief Determine whether the given set of template arguments has a pack
1958 /// expansion that is not the last template argument.
1959 static bool hasPackExpansionBeforeEnd(ArrayRef<TemplateArgument> Args) {
1960 bool FoundPackExpansion = false;
1961 for (const auto &A : Args) {
1962 if (FoundPackExpansion)
1965 if (A.getKind() == TemplateArgument::Pack)
1966 return hasPackExpansionBeforeEnd(A.pack_elements());
1968 if (A.isPackExpansion())
1969 FoundPackExpansion = true;
1975 static Sema::TemplateDeductionResult
1976 DeduceTemplateArguments(Sema &S, TemplateParameterList *TemplateParams,
1977 ArrayRef<TemplateArgument> Params,
1978 ArrayRef<TemplateArgument> Args,
1979 TemplateDeductionInfo &Info,
1980 SmallVectorImpl<DeducedTemplateArgument> &Deduced,
1981 bool NumberOfArgumentsMustMatch) {
1982 // C++0x [temp.deduct.type]p9:
1983 // If the template argument list of P contains a pack expansion that is not
1984 // the last template argument, the entire template argument list is a
1985 // non-deduced context.
1986 if (hasPackExpansionBeforeEnd(Params))
1987 return Sema::TDK_Success;
1989 // C++0x [temp.deduct.type]p9:
1990 // If P has a form that contains <T> or <i>, then each argument Pi of the
1991 // respective template argument list P is compared with the corresponding
1992 // argument Ai of the corresponding template argument list of A.
1993 unsigned ArgIdx = 0, ParamIdx = 0;
1994 for (; hasTemplateArgumentForDeduction(Params, ParamIdx); ++ParamIdx) {
1995 if (!Params[ParamIdx].isPackExpansion()) {
1996 // The simple case: deduce template arguments by matching Pi and Ai.
1998 // Check whether we have enough arguments.
1999 if (!hasTemplateArgumentForDeduction(Args, ArgIdx))
2000 return NumberOfArgumentsMustMatch
2001 ? Sema::TDK_MiscellaneousDeductionFailure
2002 : Sema::TDK_Success;
2004 // C++1z [temp.deduct.type]p9:
2005 // During partial ordering, if Ai was originally a pack expansion [and]
2006 // Pi is not a pack expansion, template argument deduction fails.
2007 if (Args[ArgIdx].isPackExpansion())
2008 return Sema::TDK_MiscellaneousDeductionFailure;
2010 // Perform deduction for this Pi/Ai pair.
2011 if (Sema::TemplateDeductionResult Result
2012 = DeduceTemplateArguments(S, TemplateParams,
2013 Params[ParamIdx], Args[ArgIdx],
2017 // Move to the next argument.
2022 // The parameter is a pack expansion.
2024 // C++0x [temp.deduct.type]p9:
2025 // If Pi is a pack expansion, then the pattern of Pi is compared with
2026 // each remaining argument in the template argument list of A. Each
2027 // comparison deduces template arguments for subsequent positions in the
2028 // template parameter packs expanded by Pi.
2029 TemplateArgument Pattern = Params[ParamIdx].getPackExpansionPattern();
2031 // FIXME: If there are no remaining arguments, we can bail out early
2032 // and set any deduced parameter packs to an empty argument pack.
2033 // The latter part of this is a (minor) correctness issue.
2035 // Prepare to deduce the packs within the pattern.
2036 PackDeductionScope PackScope(S, TemplateParams, Deduced, Info, Pattern);
2038 // Keep track of the deduced template arguments for each parameter pack
2039 // expanded by this pack expansion (the outer index) and for each
2040 // template argument (the inner SmallVectors).
2041 for (; hasTemplateArgumentForDeduction(Args, ArgIdx); ++ArgIdx) {
2042 // Deduce template arguments from the pattern.
2043 if (Sema::TemplateDeductionResult Result
2044 = DeduceTemplateArguments(S, TemplateParams, Pattern, Args[ArgIdx],
2048 PackScope.nextPackElement();
2051 // Build argument packs for each of the parameter packs expanded by this
2053 if (auto Result = PackScope.finish())
2057 return Sema::TDK_Success;
2060 static Sema::TemplateDeductionResult
2061 DeduceTemplateArguments(Sema &S,
2062 TemplateParameterList *TemplateParams,
2063 const TemplateArgumentList &ParamList,
2064 const TemplateArgumentList &ArgList,
2065 TemplateDeductionInfo &Info,
2066 SmallVectorImpl<DeducedTemplateArgument> &Deduced) {
2067 return DeduceTemplateArguments(S, TemplateParams, ParamList.asArray(),
2068 ArgList.asArray(), Info, Deduced,
2069 /*NumberOfArgumentsMustMatch*/false);
2072 /// \brief Determine whether two template arguments are the same.
2073 static bool isSameTemplateArg(ASTContext &Context,
2075 const TemplateArgument &Y,
2076 bool PackExpansionMatchesPack = false) {
2077 // If we're checking deduced arguments (X) against original arguments (Y),
2078 // we will have flattened packs to non-expansions in X.
2079 if (PackExpansionMatchesPack && X.isPackExpansion() && !Y.isPackExpansion())
2080 X = X.getPackExpansionPattern();
2082 if (X.getKind() != Y.getKind())
2085 switch (X.getKind()) {
2086 case TemplateArgument::Null:
2087 llvm_unreachable("Comparing NULL template argument");
2089 case TemplateArgument::Type:
2090 return Context.getCanonicalType(X.getAsType()) ==
2091 Context.getCanonicalType(Y.getAsType());
2093 case TemplateArgument::Declaration:
2094 return isSameDeclaration(X.getAsDecl(), Y.getAsDecl());
2096 case TemplateArgument::NullPtr:
2097 return Context.hasSameType(X.getNullPtrType(), Y.getNullPtrType());
2099 case TemplateArgument::Template:
2100 case TemplateArgument::TemplateExpansion:
2101 return Context.getCanonicalTemplateName(
2102 X.getAsTemplateOrTemplatePattern()).getAsVoidPointer() ==
2103 Context.getCanonicalTemplateName(
2104 Y.getAsTemplateOrTemplatePattern()).getAsVoidPointer();
2106 case TemplateArgument::Integral:
2107 return hasSameExtendedValue(X.getAsIntegral(), Y.getAsIntegral());
2109 case TemplateArgument::Expression: {
2110 llvm::FoldingSetNodeID XID, YID;
2111 X.getAsExpr()->Profile(XID, Context, true);
2112 Y.getAsExpr()->Profile(YID, Context, true);
2116 case TemplateArgument::Pack:
2117 if (X.pack_size() != Y.pack_size())
2120 for (TemplateArgument::pack_iterator XP = X.pack_begin(),
2121 XPEnd = X.pack_end(),
2122 YP = Y.pack_begin();
2123 XP != XPEnd; ++XP, ++YP)
2124 if (!isSameTemplateArg(Context, *XP, *YP, PackExpansionMatchesPack))
2130 llvm_unreachable("Invalid TemplateArgument Kind!");
2133 /// \brief Allocate a TemplateArgumentLoc where all locations have
2134 /// been initialized to the given location.
2136 /// \param Arg The template argument we are producing template argument
2137 /// location information for.
2139 /// \param NTTPType For a declaration template argument, the type of
2140 /// the non-type template parameter that corresponds to this template
2141 /// argument. Can be null if no type sugar is available to add to the
2142 /// type from the template argument.
2144 /// \param Loc The source location to use for the resulting template
2147 Sema::getTrivialTemplateArgumentLoc(const TemplateArgument &Arg,
2148 QualType NTTPType, SourceLocation Loc) {
2149 switch (Arg.getKind()) {
2150 case TemplateArgument::Null:
2151 llvm_unreachable("Can't get a NULL template argument here");
2153 case TemplateArgument::Type:
2154 return TemplateArgumentLoc(
2155 Arg, Context.getTrivialTypeSourceInfo(Arg.getAsType(), Loc));
2157 case TemplateArgument::Declaration: {
2158 if (NTTPType.isNull())
2159 NTTPType = Arg.getParamTypeForDecl();
2160 Expr *E = BuildExpressionFromDeclTemplateArgument(Arg, NTTPType, Loc)
2162 return TemplateArgumentLoc(TemplateArgument(E), E);
2165 case TemplateArgument::NullPtr: {
2166 if (NTTPType.isNull())
2167 NTTPType = Arg.getNullPtrType();
2168 Expr *E = BuildExpressionFromDeclTemplateArgument(Arg, NTTPType, Loc)
2170 return TemplateArgumentLoc(TemplateArgument(NTTPType, /*isNullPtr*/true),
2174 case TemplateArgument::Integral: {
2176 BuildExpressionFromIntegralTemplateArgument(Arg, Loc).getAs<Expr>();
2177 return TemplateArgumentLoc(TemplateArgument(E), E);
2180 case TemplateArgument::Template:
2181 case TemplateArgument::TemplateExpansion: {
2182 NestedNameSpecifierLocBuilder Builder;
2183 TemplateName Template = Arg.getAsTemplate();
2184 if (DependentTemplateName *DTN = Template.getAsDependentTemplateName())
2185 Builder.MakeTrivial(Context, DTN->getQualifier(), Loc);
2186 else if (QualifiedTemplateName *QTN =
2187 Template.getAsQualifiedTemplateName())
2188 Builder.MakeTrivial(Context, QTN->getQualifier(), Loc);
2190 if (Arg.getKind() == TemplateArgument::Template)
2191 return TemplateArgumentLoc(Arg, Builder.getWithLocInContext(Context),
2194 return TemplateArgumentLoc(Arg, Builder.getWithLocInContext(Context),
2198 case TemplateArgument::Expression:
2199 return TemplateArgumentLoc(Arg, Arg.getAsExpr());
2201 case TemplateArgument::Pack:
2202 return TemplateArgumentLoc(Arg, TemplateArgumentLocInfo());
2205 llvm_unreachable("Invalid TemplateArgument Kind!");
2209 /// \brief Convert the given deduced template argument and add it to the set of
2210 /// fully-converted template arguments.
2212 ConvertDeducedTemplateArgument(Sema &S, NamedDecl *Param,
2213 DeducedTemplateArgument Arg,
2214 NamedDecl *Template,
2215 TemplateDeductionInfo &Info,
2217 SmallVectorImpl<TemplateArgument> &Output) {
2218 auto ConvertArg = [&](DeducedTemplateArgument Arg,
2219 unsigned ArgumentPackIndex) {
2220 // Convert the deduced template argument into a template
2221 // argument that we can check, almost as if the user had written
2222 // the template argument explicitly.
2223 TemplateArgumentLoc ArgLoc =
2224 S.getTrivialTemplateArgumentLoc(Arg, QualType(), Info.getLocation());
2226 // Check the template argument, converting it as necessary.
2227 return S.CheckTemplateArgument(
2228 Param, ArgLoc, Template, Template->getLocation(),
2229 Template->getSourceRange().getEnd(), ArgumentPackIndex, Output,
2231 ? (Arg.wasDeducedFromArrayBound() ? Sema::CTAK_DeducedFromArrayBound
2232 : Sema::CTAK_Deduced)
2233 : Sema::CTAK_Specified);
2236 if (Arg.getKind() == TemplateArgument::Pack) {
2237 // This is a template argument pack, so check each of its arguments against
2238 // the template parameter.
2239 SmallVector<TemplateArgument, 2> PackedArgsBuilder;
2240 for (const auto &P : Arg.pack_elements()) {
2241 // When converting the deduced template argument, append it to the
2242 // general output list. We need to do this so that the template argument
2243 // checking logic has all of the prior template arguments available.
2244 DeducedTemplateArgument InnerArg(P);
2245 InnerArg.setDeducedFromArrayBound(Arg.wasDeducedFromArrayBound());
2246 assert(InnerArg.getKind() != TemplateArgument::Pack &&
2247 "deduced nested pack");
2249 // We deduced arguments for some elements of this pack, but not for
2250 // all of them. This happens if we get a conditionally-non-deduced
2251 // context in a pack expansion (such as an overload set in one of the
2253 S.Diag(Param->getLocation(),
2254 diag::err_template_arg_deduced_incomplete_pack)
2258 if (ConvertArg(InnerArg, PackedArgsBuilder.size()))
2261 // Move the converted template argument into our argument pack.
2262 PackedArgsBuilder.push_back(Output.pop_back_val());
2265 // If the pack is empty, we still need to substitute into the parameter
2266 // itself, in case that substitution fails.
2267 if (PackedArgsBuilder.empty()) {
2268 LocalInstantiationScope Scope(S);
2269 TemplateArgumentList TemplateArgs(TemplateArgumentList::OnStack, Output);
2270 MultiLevelTemplateArgumentList Args(TemplateArgs);
2272 if (auto *NTTP = dyn_cast<NonTypeTemplateParmDecl>(Param)) {
2273 Sema::InstantiatingTemplate Inst(S, Template->getLocation(), Template,
2275 Template->getSourceRange());
2276 if (Inst.isInvalid() ||
2277 S.SubstType(NTTP->getType(), Args, NTTP->getLocation(),
2278 NTTP->getDeclName()).isNull())
2280 } else if (auto *TTP = dyn_cast<TemplateTemplateParmDecl>(Param)) {
2281 Sema::InstantiatingTemplate Inst(S, Template->getLocation(), Template,
2283 Template->getSourceRange());
2284 if (Inst.isInvalid() || !S.SubstDecl(TTP, S.CurContext, Args))
2287 // For type parameters, no substitution is ever required.
2290 // Create the resulting argument pack.
2292 TemplateArgument::CreatePackCopy(S.Context, PackedArgsBuilder));
2296 return ConvertArg(Arg, 0);
2299 // FIXME: This should not be a template, but
2300 // ClassTemplatePartialSpecializationDecl sadly does not derive from
2302 template<typename TemplateDeclT>
2303 static Sema::TemplateDeductionResult ConvertDeducedTemplateArguments(
2304 Sema &S, TemplateDeclT *Template, bool IsDeduced,
2305 SmallVectorImpl<DeducedTemplateArgument> &Deduced,
2306 TemplateDeductionInfo &Info, SmallVectorImpl<TemplateArgument> &Builder,
2307 LocalInstantiationScope *CurrentInstantiationScope = nullptr,
2308 unsigned NumAlreadyConverted = 0, bool PartialOverloading = false) {
2309 TemplateParameterList *TemplateParams = Template->getTemplateParameters();
2311 for (unsigned I = 0, N = TemplateParams->size(); I != N; ++I) {
2312 NamedDecl *Param = TemplateParams->getParam(I);
2314 if (!Deduced[I].isNull()) {
2315 if (I < NumAlreadyConverted) {
2316 // We may have had explicitly-specified template arguments for a
2317 // template parameter pack (that may or may not have been extended
2318 // via additional deduced arguments).
2319 if (Param->isParameterPack() && CurrentInstantiationScope &&
2320 CurrentInstantiationScope->getPartiallySubstitutedPack() == Param) {
2321 // Forget the partially-substituted pack; its substitution is now
2323 CurrentInstantiationScope->ResetPartiallySubstitutedPack();
2324 // We still need to check the argument in case it was extended by
2327 // We have already fully type-checked and converted this
2328 // argument, because it was explicitly-specified. Just record the
2329 // presence of this argument.
2330 Builder.push_back(Deduced[I]);
2335 // We may have deduced this argument, so it still needs to be
2336 // checked and converted.
2337 if (ConvertDeducedTemplateArgument(S, Param, Deduced[I], Template, Info,
2338 IsDeduced, Builder)) {
2339 Info.Param = makeTemplateParameter(Param);
2340 // FIXME: These template arguments are temporary. Free them!
2341 Info.reset(TemplateArgumentList::CreateCopy(S.Context, Builder));
2342 return Sema::TDK_SubstitutionFailure;
2348 // C++0x [temp.arg.explicit]p3:
2349 // A trailing template parameter pack (14.5.3) not otherwise deduced will
2350 // be deduced to an empty sequence of template arguments.
2351 // FIXME: Where did the word "trailing" come from?
2352 if (Param->isTemplateParameterPack()) {
2353 // We may have had explicitly-specified template arguments for this
2354 // template parameter pack. If so, our empty deduction extends the
2355 // explicitly-specified set (C++0x [temp.arg.explicit]p9).
2356 const TemplateArgument *ExplicitArgs;
2357 unsigned NumExplicitArgs;
2358 if (CurrentInstantiationScope &&
2359 CurrentInstantiationScope->getPartiallySubstitutedPack(
2360 &ExplicitArgs, &NumExplicitArgs) == Param) {
2361 Builder.push_back(TemplateArgument(
2362 llvm::makeArrayRef(ExplicitArgs, NumExplicitArgs)));
2364 // Forget the partially-substituted pack; its substitution is now
2366 CurrentInstantiationScope->ResetPartiallySubstitutedPack();
2368 // Go through the motions of checking the empty argument pack against
2369 // the parameter pack.
2370 DeducedTemplateArgument DeducedPack(TemplateArgument::getEmptyPack());
2371 if (ConvertDeducedTemplateArgument(S, Param, DeducedPack, Template,
2372 Info, IsDeduced, Builder)) {
2373 Info.Param = makeTemplateParameter(Param);
2374 // FIXME: These template arguments are temporary. Free them!
2375 Info.reset(TemplateArgumentList::CreateCopy(S.Context, Builder));
2376 return Sema::TDK_SubstitutionFailure;
2382 // Substitute into the default template argument, if available.
2383 bool HasDefaultArg = false;
2384 TemplateDecl *TD = dyn_cast<TemplateDecl>(Template);
2386 assert(isa<ClassTemplatePartialSpecializationDecl>(Template));
2387 return Sema::TDK_Incomplete;
2390 TemplateArgumentLoc DefArg = S.SubstDefaultTemplateArgumentIfAvailable(
2391 TD, TD->getLocation(), TD->getSourceRange().getEnd(), Param, Builder,
2394 // If there was no default argument, deduction is incomplete.
2395 if (DefArg.getArgument().isNull()) {
2396 Info.Param = makeTemplateParameter(
2397 const_cast<NamedDecl *>(TemplateParams->getParam(I)));
2398 Info.reset(TemplateArgumentList::CreateCopy(S.Context, Builder));
2399 if (PartialOverloading) break;
2401 return HasDefaultArg ? Sema::TDK_SubstitutionFailure
2402 : Sema::TDK_Incomplete;
2405 // Check whether we can actually use the default argument.
2406 if (S.CheckTemplateArgument(Param, DefArg, TD, TD->getLocation(),
2407 TD->getSourceRange().getEnd(), 0, Builder,
2408 Sema::CTAK_Specified)) {
2409 Info.Param = makeTemplateParameter(
2410 const_cast<NamedDecl *>(TemplateParams->getParam(I)));
2411 // FIXME: These template arguments are temporary. Free them!
2412 Info.reset(TemplateArgumentList::CreateCopy(S.Context, Builder));
2413 return Sema::TDK_SubstitutionFailure;
2416 // If we get here, we successfully used the default template argument.
2419 return Sema::TDK_Success;
2422 static DeclContext *getAsDeclContextOrEnclosing(Decl *D) {
2423 if (auto *DC = dyn_cast<DeclContext>(D))
2425 return D->getDeclContext();
2428 template<typename T> struct IsPartialSpecialization {
2429 static constexpr bool value = false;
2432 struct IsPartialSpecialization<ClassTemplatePartialSpecializationDecl> {
2433 static constexpr bool value = true;
2436 struct IsPartialSpecialization<VarTemplatePartialSpecializationDecl> {
2437 static constexpr bool value = true;
2440 /// Complete template argument deduction for a partial specialization.
2441 template <typename T>
2442 static typename std::enable_if<IsPartialSpecialization<T>::value,
2443 Sema::TemplateDeductionResult>::type
2444 FinishTemplateArgumentDeduction(
2445 Sema &S, T *Partial, bool IsPartialOrdering,
2446 const TemplateArgumentList &TemplateArgs,
2447 SmallVectorImpl<DeducedTemplateArgument> &Deduced,
2448 TemplateDeductionInfo &Info) {
2449 // Unevaluated SFINAE context.
2450 EnterExpressionEvaluationContext Unevaluated(
2451 S, Sema::ExpressionEvaluationContext::Unevaluated);
2452 Sema::SFINAETrap Trap(S);
2454 Sema::ContextRAII SavedContext(S, getAsDeclContextOrEnclosing(Partial));
2456 // C++ [temp.deduct.type]p2:
2457 // [...] or if any template argument remains neither deduced nor
2458 // explicitly specified, template argument deduction fails.
2459 SmallVector<TemplateArgument, 4> Builder;
2460 if (auto Result = ConvertDeducedTemplateArguments(
2461 S, Partial, IsPartialOrdering, Deduced, Info, Builder))
2464 // Form the template argument list from the deduced template arguments.
2465 TemplateArgumentList *DeducedArgumentList
2466 = TemplateArgumentList::CreateCopy(S.Context, Builder);
2468 Info.reset(DeducedArgumentList);
2470 // Substitute the deduced template arguments into the template
2471 // arguments of the class template partial specialization, and
2472 // verify that the instantiated template arguments are both valid
2473 // and are equivalent to the template arguments originally provided
2474 // to the class template.
2475 LocalInstantiationScope InstScope(S);
2476 auto *Template = Partial->getSpecializedTemplate();
2477 const ASTTemplateArgumentListInfo *PartialTemplArgInfo =
2478 Partial->getTemplateArgsAsWritten();
2479 const TemplateArgumentLoc *PartialTemplateArgs =
2480 PartialTemplArgInfo->getTemplateArgs();
2482 TemplateArgumentListInfo InstArgs(PartialTemplArgInfo->LAngleLoc,
2483 PartialTemplArgInfo->RAngleLoc);
2485 if (S.Subst(PartialTemplateArgs, PartialTemplArgInfo->NumTemplateArgs,
2486 InstArgs, MultiLevelTemplateArgumentList(*DeducedArgumentList))) {
2487 unsigned ArgIdx = InstArgs.size(), ParamIdx = ArgIdx;
2488 if (ParamIdx >= Partial->getTemplateParameters()->size())
2489 ParamIdx = Partial->getTemplateParameters()->size() - 1;
2491 Decl *Param = const_cast<NamedDecl *>(
2492 Partial->getTemplateParameters()->getParam(ParamIdx));
2493 Info.Param = makeTemplateParameter(Param);
2494 Info.FirstArg = PartialTemplateArgs[ArgIdx].getArgument();
2495 return Sema::TDK_SubstitutionFailure;
2498 SmallVector<TemplateArgument, 4> ConvertedInstArgs;
2499 if (S.CheckTemplateArgumentList(Template, Partial->getLocation(), InstArgs,
2500 false, ConvertedInstArgs))
2501 return Sema::TDK_SubstitutionFailure;
2503 TemplateParameterList *TemplateParams = Template->getTemplateParameters();
2504 for (unsigned I = 0, E = TemplateParams->size(); I != E; ++I) {
2505 TemplateArgument InstArg = ConvertedInstArgs.data()[I];
2506 if (!isSameTemplateArg(S.Context, TemplateArgs[I], InstArg)) {
2507 Info.Param = makeTemplateParameter(TemplateParams->getParam(I));
2508 Info.FirstArg = TemplateArgs[I];
2509 Info.SecondArg = InstArg;
2510 return Sema::TDK_NonDeducedMismatch;
2514 if (Trap.hasErrorOccurred())
2515 return Sema::TDK_SubstitutionFailure;
2517 return Sema::TDK_Success;
2520 /// Complete template argument deduction for a class or variable template,
2521 /// when partial ordering against a partial specialization.
2522 // FIXME: Factor out duplication with partial specialization version above.
2523 static Sema::TemplateDeductionResult FinishTemplateArgumentDeduction(
2524 Sema &S, TemplateDecl *Template, bool PartialOrdering,
2525 const TemplateArgumentList &TemplateArgs,
2526 SmallVectorImpl<DeducedTemplateArgument> &Deduced,
2527 TemplateDeductionInfo &Info) {
2528 // Unevaluated SFINAE context.
2529 EnterExpressionEvaluationContext Unevaluated(
2530 S, Sema::ExpressionEvaluationContext::Unevaluated);
2531 Sema::SFINAETrap Trap(S);
2533 Sema::ContextRAII SavedContext(S, getAsDeclContextOrEnclosing(Template));
2535 // C++ [temp.deduct.type]p2:
2536 // [...] or if any template argument remains neither deduced nor
2537 // explicitly specified, template argument deduction fails.
2538 SmallVector<TemplateArgument, 4> Builder;
2539 if (auto Result = ConvertDeducedTemplateArguments(
2540 S, Template, /*IsDeduced*/PartialOrdering, Deduced, Info, Builder))
2543 // Check that we produced the correct argument list.
2544 TemplateParameterList *TemplateParams = Template->getTemplateParameters();
2545 for (unsigned I = 0, E = TemplateParams->size(); I != E; ++I) {
2546 TemplateArgument InstArg = Builder[I];
2547 if (!isSameTemplateArg(S.Context, TemplateArgs[I], InstArg,
2548 /*PackExpansionMatchesPack*/true)) {
2549 Info.Param = makeTemplateParameter(TemplateParams->getParam(I));
2550 Info.FirstArg = TemplateArgs[I];
2551 Info.SecondArg = InstArg;
2552 return Sema::TDK_NonDeducedMismatch;
2556 if (Trap.hasErrorOccurred())
2557 return Sema::TDK_SubstitutionFailure;
2559 return Sema::TDK_Success;
2563 /// \brief Perform template argument deduction to determine whether
2564 /// the given template arguments match the given class template
2565 /// partial specialization per C++ [temp.class.spec.match].
2566 Sema::TemplateDeductionResult
2567 Sema::DeduceTemplateArguments(ClassTemplatePartialSpecializationDecl *Partial,
2568 const TemplateArgumentList &TemplateArgs,
2569 TemplateDeductionInfo &Info) {
2570 if (Partial->isInvalidDecl())
2573 // C++ [temp.class.spec.match]p2:
2574 // A partial specialization matches a given actual template
2575 // argument list if the template arguments of the partial
2576 // specialization can be deduced from the actual template argument
2579 // Unevaluated SFINAE context.
2580 EnterExpressionEvaluationContext Unevaluated(
2581 *this, Sema::ExpressionEvaluationContext::Unevaluated);
2582 SFINAETrap Trap(*this);
2584 SmallVector<DeducedTemplateArgument, 4> Deduced;
2585 Deduced.resize(Partial->getTemplateParameters()->size());
2586 if (TemplateDeductionResult Result
2587 = ::DeduceTemplateArguments(*this,
2588 Partial->getTemplateParameters(),
2589 Partial->getTemplateArgs(),
2590 TemplateArgs, Info, Deduced))
2593 SmallVector<TemplateArgument, 4> DeducedArgs(Deduced.begin(), Deduced.end());
2594 InstantiatingTemplate Inst(*this, Info.getLocation(), Partial, DeducedArgs,
2596 if (Inst.isInvalid())
2597 return TDK_InstantiationDepth;
2599 if (Trap.hasErrorOccurred())
2600 return Sema::TDK_SubstitutionFailure;
2602 return ::FinishTemplateArgumentDeduction(
2603 *this, Partial, /*PartialOrdering=*/false, TemplateArgs, Deduced, Info);
2606 /// \brief Perform template argument deduction to determine whether
2607 /// the given template arguments match the given variable template
2608 /// partial specialization per C++ [temp.class.spec.match].
2609 Sema::TemplateDeductionResult
2610 Sema::DeduceTemplateArguments(VarTemplatePartialSpecializationDecl *Partial,
2611 const TemplateArgumentList &TemplateArgs,
2612 TemplateDeductionInfo &Info) {
2613 if (Partial->isInvalidDecl())
2616 // C++ [temp.class.spec.match]p2:
2617 // A partial specialization matches a given actual template
2618 // argument list if the template arguments of the partial
2619 // specialization can be deduced from the actual template argument
2622 // Unevaluated SFINAE context.
2623 EnterExpressionEvaluationContext Unevaluated(
2624 *this, Sema::ExpressionEvaluationContext::Unevaluated);
2625 SFINAETrap Trap(*this);
2627 SmallVector<DeducedTemplateArgument, 4> Deduced;
2628 Deduced.resize(Partial->getTemplateParameters()->size());
2629 if (TemplateDeductionResult Result = ::DeduceTemplateArguments(
2630 *this, Partial->getTemplateParameters(), Partial->getTemplateArgs(),
2631 TemplateArgs, Info, Deduced))
2634 SmallVector<TemplateArgument, 4> DeducedArgs(Deduced.begin(), Deduced.end());
2635 InstantiatingTemplate Inst(*this, Info.getLocation(), Partial, DeducedArgs,
2637 if (Inst.isInvalid())
2638 return TDK_InstantiationDepth;
2640 if (Trap.hasErrorOccurred())
2641 return Sema::TDK_SubstitutionFailure;
2643 return ::FinishTemplateArgumentDeduction(
2644 *this, Partial, /*PartialOrdering=*/false, TemplateArgs, Deduced, Info);
2647 /// \brief Determine whether the given type T is a simple-template-id type.
2648 static bool isSimpleTemplateIdType(QualType T) {
2649 if (const TemplateSpecializationType *Spec
2650 = T->getAs<TemplateSpecializationType>())
2651 return Spec->getTemplateName().getAsTemplateDecl() != nullptr;
2656 /// \brief Substitute the explicitly-provided template arguments into the
2657 /// given function template according to C++ [temp.arg.explicit].
2659 /// \param FunctionTemplate the function template into which the explicit
2660 /// template arguments will be substituted.
2662 /// \param ExplicitTemplateArgs the explicitly-specified template
2665 /// \param Deduced the deduced template arguments, which will be populated
2666 /// with the converted and checked explicit template arguments.
2668 /// \param ParamTypes will be populated with the instantiated function
2671 /// \param FunctionType if non-NULL, the result type of the function template
2672 /// will also be instantiated and the pointed-to value will be updated with
2673 /// the instantiated function type.
2675 /// \param Info if substitution fails for any reason, this object will be
2676 /// populated with more information about the failure.
2678 /// \returns TDK_Success if substitution was successful, or some failure
2680 Sema::TemplateDeductionResult
2681 Sema::SubstituteExplicitTemplateArguments(
2682 FunctionTemplateDecl *FunctionTemplate,
2683 TemplateArgumentListInfo &ExplicitTemplateArgs,
2684 SmallVectorImpl<DeducedTemplateArgument> &Deduced,
2685 SmallVectorImpl<QualType> &ParamTypes,
2686 QualType *FunctionType,
2687 TemplateDeductionInfo &Info) {
2688 FunctionDecl *Function = FunctionTemplate->getTemplatedDecl();
2689 TemplateParameterList *TemplateParams
2690 = FunctionTemplate->getTemplateParameters();
2692 if (ExplicitTemplateArgs.size() == 0) {
2693 // No arguments to substitute; just copy over the parameter types and
2694 // fill in the function type.
2695 for (auto P : Function->parameters())
2696 ParamTypes.push_back(P->getType());
2699 *FunctionType = Function->getType();
2703 // Unevaluated SFINAE context.
2704 EnterExpressionEvaluationContext Unevaluated(
2705 *this, Sema::ExpressionEvaluationContext::Unevaluated);
2706 SFINAETrap Trap(*this);
2708 // C++ [temp.arg.explicit]p3:
2709 // Template arguments that are present shall be specified in the
2710 // declaration order of their corresponding template-parameters. The
2711 // template argument list shall not specify more template-arguments than
2712 // there are corresponding template-parameters.
2713 SmallVector<TemplateArgument, 4> Builder;
2715 // Enter a new template instantiation context where we check the
2716 // explicitly-specified template arguments against this function template,
2717 // and then substitute them into the function parameter types.
2718 SmallVector<TemplateArgument, 4> DeducedArgs;
2719 InstantiatingTemplate Inst(
2720 *this, Info.getLocation(), FunctionTemplate, DeducedArgs,
2721 CodeSynthesisContext::ExplicitTemplateArgumentSubstitution, Info);
2722 if (Inst.isInvalid())
2723 return TDK_InstantiationDepth;
2725 if (CheckTemplateArgumentList(FunctionTemplate, SourceLocation(),
2726 ExplicitTemplateArgs, true, Builder, false) ||
2727 Trap.hasErrorOccurred()) {
2728 unsigned Index = Builder.size();
2729 if (Index >= TemplateParams->size())
2730 Index = TemplateParams->size() - 1;
2731 Info.Param = makeTemplateParameter(TemplateParams->getParam(Index));
2732 return TDK_InvalidExplicitArguments;
2735 // Form the template argument list from the explicitly-specified
2736 // template arguments.
2737 TemplateArgumentList *ExplicitArgumentList
2738 = TemplateArgumentList::CreateCopy(Context, Builder);
2739 Info.reset(ExplicitArgumentList);
2741 // Template argument deduction and the final substitution should be
2742 // done in the context of the templated declaration. Explicit
2743 // argument substitution, on the other hand, needs to happen in the
2745 ContextRAII SavedContext(*this, FunctionTemplate->getTemplatedDecl());
2747 // If we deduced template arguments for a template parameter pack,
2748 // note that the template argument pack is partially substituted and record
2749 // the explicit template arguments. They'll be used as part of deduction
2750 // for this template parameter pack.
2751 for (unsigned I = 0, N = Builder.size(); I != N; ++I) {
2752 const TemplateArgument &Arg = Builder[I];
2753 if (Arg.getKind() == TemplateArgument::Pack) {
2754 CurrentInstantiationScope->SetPartiallySubstitutedPack(
2755 TemplateParams->getParam(I),
2762 const FunctionProtoType *Proto
2763 = Function->getType()->getAs<FunctionProtoType>();
2764 assert(Proto && "Function template does not have a prototype?");
2766 // Isolate our substituted parameters from our caller.
2767 LocalInstantiationScope InstScope(*this, /*MergeWithOuterScope*/true);
2769 ExtParameterInfoBuilder ExtParamInfos;
2771 // Instantiate the types of each of the function parameters given the
2772 // explicitly-specified template arguments. If the function has a trailing
2773 // return type, substitute it after the arguments to ensure we substitute
2774 // in lexical order.
2775 if (Proto->hasTrailingReturn()) {
2776 if (SubstParmTypes(Function->getLocation(), Function->parameters(),
2777 Proto->getExtParameterInfosOrNull(),
2778 MultiLevelTemplateArgumentList(*ExplicitArgumentList),
2779 ParamTypes, /*params*/ nullptr, ExtParamInfos))
2780 return TDK_SubstitutionFailure;
2783 // Instantiate the return type.
2784 QualType ResultType;
2786 // C++11 [expr.prim.general]p3:
2787 // If a declaration declares a member function or member function
2788 // template of a class X, the expression this is a prvalue of type
2789 // "pointer to cv-qualifier-seq X" between the optional cv-qualifer-seq
2790 // and the end of the function-definition, member-declarator, or
2792 unsigned ThisTypeQuals = 0;
2793 CXXRecordDecl *ThisContext = nullptr;
2794 if (CXXMethodDecl *Method = dyn_cast<CXXMethodDecl>(Function)) {
2795 ThisContext = Method->getParent();
2796 ThisTypeQuals = Method->getTypeQualifiers();
2799 CXXThisScopeRAII ThisScope(*this, ThisContext, ThisTypeQuals,
2800 getLangOpts().CPlusPlus11);
2803 SubstType(Proto->getReturnType(),
2804 MultiLevelTemplateArgumentList(*ExplicitArgumentList),
2805 Function->getTypeSpecStartLoc(), Function->getDeclName());
2806 if (ResultType.isNull() || Trap.hasErrorOccurred())
2807 return TDK_SubstitutionFailure;
2810 // Instantiate the types of each of the function parameters given the
2811 // explicitly-specified template arguments if we didn't do so earlier.
2812 if (!Proto->hasTrailingReturn() &&
2813 SubstParmTypes(Function->getLocation(), Function->parameters(),
2814 Proto->getExtParameterInfosOrNull(),
2815 MultiLevelTemplateArgumentList(*ExplicitArgumentList),
2816 ParamTypes, /*params*/ nullptr, ExtParamInfos))
2817 return TDK_SubstitutionFailure;
2820 auto EPI = Proto->getExtProtoInfo();
2821 EPI.ExtParameterInfos = ExtParamInfos.getPointerOrNull(ParamTypes.size());
2822 *FunctionType = BuildFunctionType(ResultType, ParamTypes,
2823 Function->getLocation(),
2824 Function->getDeclName(),
2826 if (FunctionType->isNull() || Trap.hasErrorOccurred())
2827 return TDK_SubstitutionFailure;
2830 // C++ [temp.arg.explicit]p2:
2831 // Trailing template arguments that can be deduced (14.8.2) may be
2832 // omitted from the list of explicit template-arguments. If all of the
2833 // template arguments can be deduced, they may all be omitted; in this
2834 // case, the empty template argument list <> itself may also be omitted.
2836 // Take all of the explicitly-specified arguments and put them into
2837 // the set of deduced template arguments. Explicitly-specified
2838 // parameter packs, however, will be set to NULL since the deduction
2839 // mechanisms handle explicitly-specified argument packs directly.
2840 Deduced.reserve(TemplateParams->size());
2841 for (unsigned I = 0, N = ExplicitArgumentList->size(); I != N; ++I) {
2842 const TemplateArgument &Arg = ExplicitArgumentList->get(I);
2843 if (Arg.getKind() == TemplateArgument::Pack)
2844 Deduced.push_back(DeducedTemplateArgument());
2846 Deduced.push_back(Arg);
2852 /// \brief Check whether the deduced argument type for a call to a function
2853 /// template matches the actual argument type per C++ [temp.deduct.call]p4.
2855 CheckOriginalCallArgDeduction(Sema &S, Sema::OriginalCallArg OriginalArg,
2856 QualType DeducedA) {
2857 ASTContext &Context = S.Context;
2859 QualType A = OriginalArg.OriginalArgType;
2860 QualType OriginalParamType = OriginalArg.OriginalParamType;
2862 // Check for type equality (top-level cv-qualifiers are ignored).
2863 if (Context.hasSameUnqualifiedType(A, DeducedA))
2866 // Strip off references on the argument types; they aren't needed for
2867 // the following checks.
2868 if (const ReferenceType *DeducedARef = DeducedA->getAs<ReferenceType>())
2869 DeducedA = DeducedARef->getPointeeType();
2870 if (const ReferenceType *ARef = A->getAs<ReferenceType>())
2871 A = ARef->getPointeeType();
2873 // C++ [temp.deduct.call]p4:
2874 // [...] However, there are three cases that allow a difference:
2875 // - If the original P is a reference type, the deduced A (i.e., the
2876 // type referred to by the reference) can be more cv-qualified than
2877 // the transformed A.
2878 if (const ReferenceType *OriginalParamRef
2879 = OriginalParamType->getAs<ReferenceType>()) {
2880 // We don't want to keep the reference around any more.
2881 OriginalParamType = OriginalParamRef->getPointeeType();
2883 // FIXME: Resolve core issue (no number yet): if the original P is a
2884 // reference type and the transformed A is function type "noexcept F",
2885 // the deduced A can be F.
2887 if (A->isFunctionType() && S.IsFunctionConversion(A, DeducedA, Tmp))
2890 Qualifiers AQuals = A.getQualifiers();
2891 Qualifiers DeducedAQuals = DeducedA.getQualifiers();
2893 // Under Objective-C++ ARC, the deduced type may have implicitly
2894 // been given strong or (when dealing with a const reference)
2895 // unsafe_unretained lifetime. If so, update the original
2896 // qualifiers to include this lifetime.
2897 if (S.getLangOpts().ObjCAutoRefCount &&
2898 ((DeducedAQuals.getObjCLifetime() == Qualifiers::OCL_Strong &&
2899 AQuals.getObjCLifetime() == Qualifiers::OCL_None) ||
2900 (DeducedAQuals.hasConst() &&
2901 DeducedAQuals.getObjCLifetime() == Qualifiers::OCL_ExplicitNone))) {
2902 AQuals.setObjCLifetime(DeducedAQuals.getObjCLifetime());
2905 if (AQuals == DeducedAQuals) {
2906 // Qualifiers match; there's nothing to do.
2907 } else if (!DeducedAQuals.compatiblyIncludes(AQuals)) {
2910 // Qualifiers are compatible, so have the argument type adopt the
2911 // deduced argument type's qualifiers as if we had performed the
2912 // qualification conversion.
2913 A = Context.getQualifiedType(A.getUnqualifiedType(), DeducedAQuals);
2917 // - The transformed A can be another pointer or pointer to member
2918 // type that can be converted to the deduced A via a function pointer
2919 // conversion and/or a qualification conversion.
2921 // Also allow conversions which merely strip __attribute__((noreturn)) from
2922 // function types (recursively).
2923 bool ObjCLifetimeConversion = false;
2925 if ((A->isAnyPointerType() || A->isMemberPointerType()) &&
2926 (S.IsQualificationConversion(A, DeducedA, false,
2927 ObjCLifetimeConversion) ||
2928 S.IsFunctionConversion(A, DeducedA, ResultTy)))
2931 // - If P is a class and P has the form simple-template-id, then the
2932 // transformed A can be a derived class of the deduced A. [...]
2933 // [...] Likewise, if P is a pointer to a class of the form
2934 // simple-template-id, the transformed A can be a pointer to a
2935 // derived class pointed to by the deduced A.
2936 if (const PointerType *OriginalParamPtr
2937 = OriginalParamType->getAs<PointerType>()) {
2938 if (const PointerType *DeducedAPtr = DeducedA->getAs<PointerType>()) {
2939 if (const PointerType *APtr = A->getAs<PointerType>()) {
2940 if (A->getPointeeType()->isRecordType()) {
2941 OriginalParamType = OriginalParamPtr->getPointeeType();
2942 DeducedA = DeducedAPtr->getPointeeType();
2943 A = APtr->getPointeeType();
2949 if (Context.hasSameUnqualifiedType(A, DeducedA))
2952 if (A->isRecordType() && isSimpleTemplateIdType(OriginalParamType) &&
2953 S.IsDerivedFrom(SourceLocation(), A, DeducedA))
2959 /// Find the pack index for a particular parameter index in an instantiation of
2960 /// a function template with specific arguments.
2962 /// \return The pack index for whichever pack produced this parameter, or -1
2963 /// if this was not produced by a parameter. Intended to be used as the
2964 /// ArgumentPackSubstitutionIndex for further substitutions.
2965 // FIXME: We should track this in OriginalCallArgs so we don't need to
2966 // reconstruct it here.
2967 static unsigned getPackIndexForParam(Sema &S,
2968 FunctionTemplateDecl *FunctionTemplate,
2969 const MultiLevelTemplateArgumentList &Args,
2970 unsigned ParamIdx) {
2972 for (auto *PD : FunctionTemplate->getTemplatedDecl()->parameters()) {
2973 if (PD->isParameterPack()) {
2974 unsigned NumExpansions =
2975 S.getNumArgumentsInExpansion(PD->getType(), Args).getValueOr(1);
2976 if (Idx + NumExpansions > ParamIdx)
2977 return ParamIdx - Idx;
2978 Idx += NumExpansions;
2980 if (Idx == ParamIdx)
2981 return -1; // Not a pack expansion
2986 llvm_unreachable("parameter index would not be produced from template");
2989 /// \brief Finish template argument deduction for a function template,
2990 /// checking the deduced template arguments for completeness and forming
2991 /// the function template specialization.
2993 /// \param OriginalCallArgs If non-NULL, the original call arguments against
2994 /// which the deduced argument types should be compared.
2995 Sema::TemplateDeductionResult Sema::FinishTemplateArgumentDeduction(
2996 FunctionTemplateDecl *FunctionTemplate,
2997 SmallVectorImpl<DeducedTemplateArgument> &Deduced,
2998 unsigned NumExplicitlySpecified, FunctionDecl *&Specialization,
2999 TemplateDeductionInfo &Info,
3000 SmallVectorImpl<OriginalCallArg> const *OriginalCallArgs,
3001 bool PartialOverloading, llvm::function_ref<bool()> CheckNonDependent) {
3002 // Unevaluated SFINAE context.
3003 EnterExpressionEvaluationContext Unevaluated(
3004 *this, Sema::ExpressionEvaluationContext::Unevaluated);
3005 SFINAETrap Trap(*this);
3007 // Enter a new template instantiation context while we instantiate the
3008 // actual function declaration.
3009 SmallVector<TemplateArgument, 4> DeducedArgs(Deduced.begin(), Deduced.end());
3010 InstantiatingTemplate Inst(
3011 *this, Info.getLocation(), FunctionTemplate, DeducedArgs,
3012 CodeSynthesisContext::DeducedTemplateArgumentSubstitution, Info);
3013 if (Inst.isInvalid())
3014 return TDK_InstantiationDepth;
3016 ContextRAII SavedContext(*this, FunctionTemplate->getTemplatedDecl());
3018 // C++ [temp.deduct.type]p2:
3019 // [...] or if any template argument remains neither deduced nor
3020 // explicitly specified, template argument deduction fails.
3021 SmallVector<TemplateArgument, 4> Builder;
3022 if (auto Result = ConvertDeducedTemplateArguments(
3023 *this, FunctionTemplate, /*IsDeduced*/true, Deduced, Info, Builder,
3024 CurrentInstantiationScope, NumExplicitlySpecified,
3025 PartialOverloading))
3028 // C++ [temp.deduct.call]p10: [DR1391]
3029 // If deduction succeeds for all parameters that contain
3030 // template-parameters that participate in template argument deduction,
3031 // and all template arguments are explicitly specified, deduced, or
3032 // obtained from default template arguments, remaining parameters are then
3033 // compared with the corresponding arguments. For each remaining parameter
3034 // P with a type that was non-dependent before substitution of any
3035 // explicitly-specified template arguments, if the corresponding argument
3036 // A cannot be implicitly converted to P, deduction fails.
3037 if (CheckNonDependent())
3038 return TDK_NonDependentConversionFailure;
3040 // Form the template argument list from the deduced template arguments.
3041 TemplateArgumentList *DeducedArgumentList
3042 = TemplateArgumentList::CreateCopy(Context, Builder);
3043 Info.reset(DeducedArgumentList);
3045 // Substitute the deduced template arguments into the function template
3046 // declaration to produce the function template specialization.
3047 DeclContext *Owner = FunctionTemplate->getDeclContext();
3048 if (FunctionTemplate->getFriendObjectKind())
3049 Owner = FunctionTemplate->getLexicalDeclContext();
3050 MultiLevelTemplateArgumentList SubstArgs(*DeducedArgumentList);
3051 Specialization = cast_or_null<FunctionDecl>(
3052 SubstDecl(FunctionTemplate->getTemplatedDecl(), Owner, SubstArgs));
3053 if (!Specialization || Specialization->isInvalidDecl())
3054 return TDK_SubstitutionFailure;
3056 assert(Specialization->getPrimaryTemplate()->getCanonicalDecl() ==
3057 FunctionTemplate->getCanonicalDecl());
3059 // If the template argument list is owned by the function template
3060 // specialization, release it.
3061 if (Specialization->getTemplateSpecializationArgs() == DeducedArgumentList &&
3062 !Trap.hasErrorOccurred())
3065 // There may have been an error that did not prevent us from constructing a
3066 // declaration. Mark the declaration invalid and return with a substitution
3068 if (Trap.hasErrorOccurred()) {
3069 Specialization->setInvalidDecl(true);
3070 return TDK_SubstitutionFailure;
3073 if (OriginalCallArgs) {
3074 // C++ [temp.deduct.call]p4:
3075 // In general, the deduction process attempts to find template argument
3076 // values that will make the deduced A identical to A (after the type A
3077 // is transformed as described above). [...]
3078 llvm::SmallDenseMap<std::pair<unsigned, QualType>, QualType> DeducedATypes;
3079 for (unsigned I = 0, N = OriginalCallArgs->size(); I != N; ++I) {
3080 OriginalCallArg OriginalArg = (*OriginalCallArgs)[I];
3082 auto ParamIdx = OriginalArg.ArgIdx;
3083 if (ParamIdx >= Specialization->getNumParams())
3084 // FIXME: This presumably means a pack ended up smaller than we
3085 // expected while deducing. Should this not result in deduction
3086 // failure? Can it even happen?
3090 if (!OriginalArg.DecomposedParam) {
3091 // P is one of the function parameters, just look up its substituted
3093 DeducedA = Specialization->getParamDecl(ParamIdx)->getType();
3095 // P is a decomposed element of a parameter corresponding to a
3096 // braced-init-list argument. Substitute back into P to find the
3098 QualType &CacheEntry =
3099 DeducedATypes[{ParamIdx, OriginalArg.OriginalParamType}];
3100 if (CacheEntry.isNull()) {
3101 ArgumentPackSubstitutionIndexRAII PackIndex(
3102 *this, getPackIndexForParam(*this, FunctionTemplate, SubstArgs,
3105 SubstType(OriginalArg.OriginalParamType, SubstArgs,
3106 Specialization->getTypeSpecStartLoc(),
3107 Specialization->getDeclName());
3109 DeducedA = CacheEntry;
3112 if (CheckOriginalCallArgDeduction(*this, OriginalArg, DeducedA)) {
3113 Info.FirstArg = TemplateArgument(DeducedA);
3114 Info.SecondArg = TemplateArgument(OriginalArg.OriginalArgType);
3115 Info.CallArgIndex = OriginalArg.ArgIdx;
3116 return OriginalArg.DecomposedParam ? TDK_DeducedMismatchNested
3117 : TDK_DeducedMismatch;
3122 // If we suppressed any diagnostics while performing template argument
3123 // deduction, and if we haven't already instantiated this declaration,
3124 // keep track of these diagnostics. They'll be emitted if this specialization
3125 // is actually used.
3126 if (Info.diag_begin() != Info.diag_end()) {
3127 SuppressedDiagnosticsMap::iterator
3128 Pos = SuppressedDiagnostics.find(Specialization->getCanonicalDecl());
3129 if (Pos == SuppressedDiagnostics.end())
3130 SuppressedDiagnostics[Specialization->getCanonicalDecl()]
3131 .append(Info.diag_begin(), Info.diag_end());
3137 /// Gets the type of a function for template-argument-deducton
3138 /// purposes when it's considered as part of an overload set.
3139 static QualType GetTypeOfFunction(Sema &S, const OverloadExpr::FindResult &R,
3141 // We may need to deduce the return type of the function now.
3142 if (S.getLangOpts().CPlusPlus14 && Fn->getReturnType()->isUndeducedType() &&
3143 S.DeduceReturnType(Fn, R.Expression->getExprLoc(), /*Diagnose*/ false))
3146 if (CXXMethodDecl *Method = dyn_cast<CXXMethodDecl>(Fn))
3147 if (Method->isInstance()) {
3148 // An instance method that's referenced in a form that doesn't
3149 // look like a member pointer is just invalid.
3150 if (!R.HasFormOfMemberPointer) return QualType();
3152 return S.Context.getMemberPointerType(Fn->getType(),
3153 S.Context.getTypeDeclType(Method->getParent()).getTypePtr());
3156 if (!R.IsAddressOfOperand) return Fn->getType();
3157 return S.Context.getPointerType(Fn->getType());
3160 /// Apply the deduction rules for overload sets.
3162 /// \return the null type if this argument should be treated as an
3163 /// undeduced context
3165 ResolveOverloadForDeduction(Sema &S, TemplateParameterList *TemplateParams,
3166 Expr *Arg, QualType ParamType,
3167 bool ParamWasReference) {
3169 OverloadExpr::FindResult R = OverloadExpr::find(Arg);
3171 OverloadExpr *Ovl = R.Expression;
3173 // C++0x [temp.deduct.call]p4
3175 if (ParamWasReference)
3176 TDF |= TDF_ParamWithReferenceType;
3177 if (R.IsAddressOfOperand)
3178 TDF |= TDF_IgnoreQualifiers;
3180 // C++0x [temp.deduct.call]p6:
3181 // When P is a function type, pointer to function type, or pointer
3182 // to member function type:
3184 if (!ParamType->isFunctionType() &&
3185 !ParamType->isFunctionPointerType() &&
3186 !ParamType->isMemberFunctionPointerType()) {
3187 if (Ovl->hasExplicitTemplateArgs()) {
3188 // But we can still look for an explicit specialization.
3189 if (FunctionDecl *ExplicitSpec
3190 = S.ResolveSingleFunctionTemplateSpecialization(Ovl))
3191 return GetTypeOfFunction(S, R, ExplicitSpec);
3195 if (FunctionDecl *Viable =
3196 S.resolveAddressOfOnlyViableOverloadCandidate(Arg, DAP))
3197 return GetTypeOfFunction(S, R, Viable);
3202 // Gather the explicit template arguments, if any.
3203 TemplateArgumentListInfo ExplicitTemplateArgs;
3204 if (Ovl->hasExplicitTemplateArgs())
3205 Ovl->copyTemplateArgumentsInto(ExplicitTemplateArgs);
3207 for (UnresolvedSetIterator I = Ovl->decls_begin(),
3208 E = Ovl->decls_end(); I != E; ++I) {
3209 NamedDecl *D = (*I)->getUnderlyingDecl();
3211 if (FunctionTemplateDecl *FunTmpl = dyn_cast<FunctionTemplateDecl>(D)) {
3212 // - If the argument is an overload set containing one or more
3213 // function templates, the parameter is treated as a
3214 // non-deduced context.
3215 if (!Ovl->hasExplicitTemplateArgs())
3218 // Otherwise, see if we can resolve a function type
3219 FunctionDecl *Specialization = nullptr;
3220 TemplateDeductionInfo Info(Ovl->getNameLoc());
3221 if (S.DeduceTemplateArguments(FunTmpl, &ExplicitTemplateArgs,
3222 Specialization, Info))
3228 FunctionDecl *Fn = cast<FunctionDecl>(D);
3229 QualType ArgType = GetTypeOfFunction(S, R, Fn);
3230 if (ArgType.isNull()) continue;
3232 // Function-to-pointer conversion.
3233 if (!ParamWasReference && ParamType->isPointerType() &&
3234 ArgType->isFunctionType())
3235 ArgType = S.Context.getPointerType(ArgType);
3237 // - If the argument is an overload set (not containing function
3238 // templates), trial argument deduction is attempted using each
3239 // of the members of the set. If deduction succeeds for only one
3240 // of the overload set members, that member is used as the
3241 // argument value for the deduction. If deduction succeeds for
3242 // more than one member of the overload set the parameter is
3243 // treated as a non-deduced context.
3245 // We do all of this in a fresh context per C++0x [temp.deduct.type]p2:
3246 // Type deduction is done independently for each P/A pair, and
3247 // the deduced template argument values are then combined.
3248 // So we do not reject deductions which were made elsewhere.
3249 SmallVector<DeducedTemplateArgument, 8>
3250 Deduced(TemplateParams->size());
3251 TemplateDeductionInfo Info(Ovl->getNameLoc());
3252 Sema::TemplateDeductionResult Result
3253 = DeduceTemplateArgumentsByTypeMatch(S, TemplateParams, ParamType,
3254 ArgType, Info, Deduced, TDF);
3255 if (Result) continue;
3256 if (!Match.isNull()) return QualType();
3263 /// \brief Perform the adjustments to the parameter and argument types
3264 /// described in C++ [temp.deduct.call].
3266 /// \returns true if the caller should not attempt to perform any template
3267 /// argument deduction based on this P/A pair because the argument is an
3268 /// overloaded function set that could not be resolved.
3269 static bool AdjustFunctionParmAndArgTypesForDeduction(
3270 Sema &S, TemplateParameterList *TemplateParams, unsigned FirstInnerIndex,
3271 QualType &ParamType, QualType &ArgType, Expr *Arg, unsigned &TDF) {
3272 // C++0x [temp.deduct.call]p3:
3273 // If P is a cv-qualified type, the top level cv-qualifiers of P's type
3274 // are ignored for type deduction.
3275 if (ParamType.hasQualifiers())
3276 ParamType = ParamType.getUnqualifiedType();
3278 // [...] If P is a reference type, the type referred to by P is
3279 // used for type deduction.
3280 const ReferenceType *ParamRefType = ParamType->getAs<ReferenceType>();
3282 ParamType = ParamRefType->getPointeeType();
3284 // Overload sets usually make this parameter an undeduced context,
3285 // but there are sometimes special circumstances. Typically
3286 // involving a template-id-expr.
3287 if (ArgType == S.Context.OverloadTy) {
3288 ArgType = ResolveOverloadForDeduction(S, TemplateParams,
3290 ParamRefType != nullptr);
3291 if (ArgType.isNull())
3296 // If the argument has incomplete array type, try to complete its type.
3297 if (ArgType->isIncompleteArrayType()) {
3298 S.completeExprArrayBound(Arg);
3299 ArgType = Arg->getType();
3302 // C++1z [temp.deduct.call]p3:
3303 // If P is a forwarding reference and the argument is an lvalue, the type
3304 // "lvalue reference to A" is used in place of A for type deduction.
3305 if (isForwardingReference(QualType(ParamRefType, 0), FirstInnerIndex) &&
3307 ArgType = S.Context.getLValueReferenceType(ArgType);
3309 // C++ [temp.deduct.call]p2:
3310 // If P is not a reference type:
3311 // - If A is an array type, the pointer type produced by the
3312 // array-to-pointer standard conversion (4.2) is used in place of
3313 // A for type deduction; otherwise,
3314 if (ArgType->isArrayType())
3315 ArgType = S.Context.getArrayDecayedType(ArgType);
3316 // - If A is a function type, the pointer type produced by the
3317 // function-to-pointer standard conversion (4.3) is used in place
3318 // of A for type deduction; otherwise,
3319 else if (ArgType->isFunctionType())
3320 ArgType = S.Context.getPointerType(ArgType);
3322 // - If A is a cv-qualified type, the top level cv-qualifiers of A's
3323 // type are ignored for type deduction.
3324 ArgType = ArgType.getUnqualifiedType();
3328 // C++0x [temp.deduct.call]p4:
3329 // In general, the deduction process attempts to find template argument
3330 // values that will make the deduced A identical to A (after the type A
3331 // is transformed as described above). [...]
3332 TDF = TDF_SkipNonDependent;
3334 // - If the original P is a reference type, the deduced A (i.e., the
3335 // type referred to by the reference) can be more cv-qualified than
3336 // the transformed A.
3338 TDF |= TDF_ParamWithReferenceType;
3339 // - The transformed A can be another pointer or pointer to member
3340 // type that can be converted to the deduced A via a qualification
3341 // conversion (4.4).
3342 if (ArgType->isPointerType() || ArgType->isMemberPointerType() ||
3343 ArgType->isObjCObjectPointerType())
3344 TDF |= TDF_IgnoreQualifiers;
3345 // - If P is a class and P has the form simple-template-id, then the
3346 // transformed A can be a derived class of the deduced A. Likewise,
3347 // if P is a pointer to a class of the form simple-template-id, the
3348 // transformed A can be a pointer to a derived class pointed to by
3350 if (isSimpleTemplateIdType(ParamType) ||
3351 (isa<PointerType>(ParamType) &&
3352 isSimpleTemplateIdType(
3353 ParamType->getAs<PointerType>()->getPointeeType())))
3354 TDF |= TDF_DerivedClass;
3360 hasDeducibleTemplateParameters(Sema &S, FunctionTemplateDecl *FunctionTemplate,
3363 static Sema::TemplateDeductionResult DeduceTemplateArgumentsFromCallArgument(
3364 Sema &S, TemplateParameterList *TemplateParams, unsigned FirstInnerIndex,
3365 QualType ParamType, Expr *Arg, TemplateDeductionInfo &Info,
3366 SmallVectorImpl<DeducedTemplateArgument> &Deduced,
3367 SmallVectorImpl<Sema::OriginalCallArg> &OriginalCallArgs,
3368 bool DecomposedParam, unsigned ArgIdx, unsigned TDF);
3370 /// \brief Attempt template argument deduction from an initializer list
3371 /// deemed to be an argument in a function call.
3372 static Sema::TemplateDeductionResult DeduceFromInitializerList(
3373 Sema &S, TemplateParameterList *TemplateParams, QualType AdjustedParamType,
3374 InitListExpr *ILE, TemplateDeductionInfo &Info,
3375 SmallVectorImpl<DeducedTemplateArgument> &Deduced,
3376 SmallVectorImpl<Sema::OriginalCallArg> &OriginalCallArgs, unsigned ArgIdx,
3378 // C++ [temp.deduct.call]p1: (CWG 1591)
3379 // If removing references and cv-qualifiers from P gives
3380 // std::initializer_list<P0> or P0[N] for some P0 and N and the argument is
3381 // a non-empty initializer list, then deduction is performed instead for
3382 // each element of the initializer list, taking P0 as a function template
3383 // parameter type and the initializer element as its argument
3385 // We've already removed references and cv-qualifiers here.
3386 if (!ILE->getNumInits())
3387 return Sema::TDK_Success;
3390 auto *ArrTy = S.Context.getAsArrayType(AdjustedParamType);
3392 ElTy = ArrTy->getElementType();
3393 else if (!S.isStdInitializerList(AdjustedParamType, &ElTy)) {
3394 // Otherwise, an initializer list argument causes the parameter to be
3395 // considered a non-deduced context
3396 return Sema::TDK_Success;
3399 // Deduction only needs to be done for dependent types.
3400 if (ElTy->isDependentType()) {
3401 for (Expr *E : ILE->inits()) {
3402 if (auto Result = DeduceTemplateArgumentsFromCallArgument(
3403 S, TemplateParams, 0, ElTy, E, Info, Deduced, OriginalCallArgs, true,
3409 // in the P0[N] case, if N is a non-type template parameter, N is deduced
3410 // from the length of the initializer list.
3411 if (auto *DependentArrTy = dyn_cast_or_null<DependentSizedArrayType>(ArrTy)) {
3412 // Determine the array bound is something we can deduce.
3413 if (NonTypeTemplateParmDecl *NTTP =
3414 getDeducedParameterFromExpr(Info, DependentArrTy->getSizeExpr())) {
3415 // We can perform template argument deduction for the given non-type
3416 // template parameter.
3417 // C++ [temp.deduct.type]p13:
3418 // The type of N in the type T[N] is std::size_t.
3419 QualType T = S.Context.getSizeType();
3420 llvm::APInt Size(S.Context.getIntWidth(T), ILE->getNumInits());
3421 if (auto Result = DeduceNonTypeTemplateArgument(
3422 S, TemplateParams, NTTP, llvm::APSInt(Size), T,
3423 /*ArrayBound=*/true, Info, Deduced))
3428 return Sema::TDK_Success;
3431 /// \brief Perform template argument deduction per [temp.deduct.call] for a
3432 /// single parameter / argument pair.
3433 static Sema::TemplateDeductionResult DeduceTemplateArgumentsFromCallArgument(
3434 Sema &S, TemplateParameterList *TemplateParams, unsigned FirstInnerIndex,
3435 QualType ParamType, Expr *Arg, TemplateDeductionInfo &Info,
3436 SmallVectorImpl<DeducedTemplateArgument> &Deduced,
3437 SmallVectorImpl<Sema::OriginalCallArg> &OriginalCallArgs,
3438 bool DecomposedParam, unsigned ArgIdx, unsigned TDF) {
3439 QualType ArgType = Arg->getType();
3440 QualType OrigParamType = ParamType;
3442 // If P is a reference type [...]
3443 // If P is a cv-qualified type [...]
3444 if (AdjustFunctionParmAndArgTypesForDeduction(
3445 S, TemplateParams, FirstInnerIndex, ParamType, ArgType, Arg, TDF))
3446 return Sema::TDK_Success;
3448 // If [...] the argument is a non-empty initializer list [...]
3449 if (InitListExpr *ILE = dyn_cast<InitListExpr>(Arg))
3450 return DeduceFromInitializerList(S, TemplateParams, ParamType, ILE, Info,
3451 Deduced, OriginalCallArgs, ArgIdx, TDF);
3453 // [...] the deduction process attempts to find template argument values
3454 // that will make the deduced A identical to A
3456 // Keep track of the argument type and corresponding parameter index,
3457 // so we can check for compatibility between the deduced A and A.
3458 OriginalCallArgs.push_back(
3459 Sema::OriginalCallArg(OrigParamType, DecomposedParam, ArgIdx, ArgType));
3460 return DeduceTemplateArgumentsByTypeMatch(S, TemplateParams, ParamType,
3461 ArgType, Info, Deduced, TDF);
3464 /// \brief Perform template argument deduction from a function call
3465 /// (C++ [temp.deduct.call]).
3467 /// \param FunctionTemplate the function template for which we are performing
3468 /// template argument deduction.
3470 /// \param ExplicitTemplateArgs the explicit template arguments provided
3473 /// \param Args the function call arguments
3475 /// \param Specialization if template argument deduction was successful,
3476 /// this will be set to the function template specialization produced by
3477 /// template argument deduction.
3479 /// \param Info the argument will be updated to provide additional information
3480 /// about template argument deduction.
3482 /// \param CheckNonDependent A callback to invoke to check conversions for
3483 /// non-dependent parameters, between deduction and substitution, per DR1391.
3484 /// If this returns true, substitution will be skipped and we return
3485 /// TDK_NonDependentConversionFailure. The callback is passed the parameter
3486 /// types (after substituting explicit template arguments).
3488 /// \returns the result of template argument deduction.
3489 Sema::TemplateDeductionResult Sema::DeduceTemplateArguments(
3490 FunctionTemplateDecl *FunctionTemplate,
3491 TemplateArgumentListInfo *ExplicitTemplateArgs, ArrayRef<Expr *> Args,
3492 FunctionDecl *&Specialization, TemplateDeductionInfo &Info,
3493 bool PartialOverloading,
3494 llvm::function_ref<bool(ArrayRef<QualType>)> CheckNonDependent) {
3495 if (FunctionTemplate->isInvalidDecl())
3498 FunctionDecl *Function = FunctionTemplate->getTemplatedDecl();
3499 unsigned NumParams = Function->getNumParams();
3501 unsigned FirstInnerIndex = getFirstInnerIndex(FunctionTemplate);
3503 // C++ [temp.deduct.call]p1:
3504 // Template argument deduction is done by comparing each function template
3505 // parameter type (call it P) with the type of the corresponding argument
3506 // of the call (call it A) as described below.
3507 if (Args.size() < Function->getMinRequiredArguments() && !PartialOverloading)
3508 return TDK_TooFewArguments;
3509 else if (TooManyArguments(NumParams, Args.size(), PartialOverloading)) {
3510 const FunctionProtoType *Proto
3511 = Function->getType()->getAs<FunctionProtoType>();
3512 if (Proto->isTemplateVariadic())
3514 else if (!Proto->isVariadic())
3515 return TDK_TooManyArguments;
3518 // The types of the parameters from which we will perform template argument
3520 LocalInstantiationScope InstScope(*this);
3521 TemplateParameterList *TemplateParams
3522 = FunctionTemplate->getTemplateParameters();
3523 SmallVector<DeducedTemplateArgument, 4> Deduced;
3524 SmallVector<QualType, 8> ParamTypes;
3525 unsigned NumExplicitlySpecified = 0;
3526 if (ExplicitTemplateArgs) {
3527 TemplateDeductionResult Result =
3528 SubstituteExplicitTemplateArguments(FunctionTemplate,
3529 *ExplicitTemplateArgs,
3537 NumExplicitlySpecified = Deduced.size();
3539 // Just fill in the parameter types from the function declaration.
3540 for (unsigned I = 0; I != NumParams; ++I)
3541 ParamTypes.push_back(Function->getParamDecl(I)->getType());
3544 SmallVector<OriginalCallArg, 8> OriginalCallArgs;
3546 // Deduce an argument of type ParamType from an expression with index ArgIdx.
3547 auto DeduceCallArgument = [&](QualType ParamType, unsigned ArgIdx) {
3548 // C++ [demp.deduct.call]p1: (DR1391)
3549 // Template argument deduction is done by comparing each function template
3550 // parameter that contains template-parameters that participate in
3551 // template argument deduction ...
3552 if (!hasDeducibleTemplateParameters(*this, FunctionTemplate, ParamType))
3553 return Sema::TDK_Success;
3555 // ... with the type of the corresponding argument
3556 return DeduceTemplateArgumentsFromCallArgument(
3557 *this, TemplateParams, FirstInnerIndex, ParamType, Args[ArgIdx], Info, Deduced,
3558 OriginalCallArgs, /*Decomposed*/false, ArgIdx, /*TDF*/ 0);
3561 // Deduce template arguments from the function parameters.
3562 Deduced.resize(TemplateParams->size());
3563 SmallVector<QualType, 8> ParamTypesForArgChecking;
3564 for (unsigned ParamIdx = 0, NumParamTypes = ParamTypes.size(), ArgIdx = 0;
3565 ParamIdx != NumParamTypes; ++ParamIdx) {
3566 QualType ParamType = ParamTypes[ParamIdx];
3568 const PackExpansionType *ParamExpansion =
3569 dyn_cast<PackExpansionType>(ParamType);
3570 if (!ParamExpansion) {
3571 // Simple case: matching a function parameter to a function argument.
3572 if (ArgIdx >= Args.size())
3575 ParamTypesForArgChecking.push_back(ParamType);
3576 if (auto Result = DeduceCallArgument(ParamType, ArgIdx++))
3582 QualType ParamPattern = ParamExpansion->getPattern();
3583 PackDeductionScope PackScope(*this, TemplateParams, Deduced, Info,
3586 // C++0x [temp.deduct.call]p1:
3587 // For a function parameter pack that occurs at the end of the
3588 // parameter-declaration-list, the type A of each remaining argument of
3589 // the call is compared with the type P of the declarator-id of the
3590 // function parameter pack. Each comparison deduces template arguments
3591 // for subsequent positions in the template parameter packs expanded by
3592 // the function parameter pack. When a function parameter pack appears
3593 // in a non-deduced context [not at the end of the list], the type of
3594 // that parameter pack is never deduced.
3596 // FIXME: The above rule allows the size of the parameter pack to change
3597 // after we skip it (in the non-deduced case). That makes no sense, so
3598 // we instead notionally deduce the pack against N arguments, where N is
3599 // the length of the explicitly-specified pack if it's expanded by the
3600 // parameter pack and 0 otherwise, and we treat each deduction as a
3601 // non-deduced context.
3602 if (ParamIdx + 1 == NumParamTypes) {
3603 for (; ArgIdx < Args.size(); PackScope.nextPackElement(), ++ArgIdx) {
3604 ParamTypesForArgChecking.push_back(ParamPattern);
3605 if (auto Result = DeduceCallArgument(ParamPattern, ArgIdx))
3609 // If the parameter type contains an explicitly-specified pack that we
3610 // could not expand, skip the number of parameters notionally created
3611 // by the expansion.
3612 Optional<unsigned> NumExpansions = ParamExpansion->getNumExpansions();
3613 if (NumExpansions && !PackScope.isPartiallyExpanded()) {
3614 for (unsigned I = 0; I != *NumExpansions && ArgIdx < Args.size();
3616 ParamTypesForArgChecking.push_back(ParamPattern);
3617 // FIXME: Should we add OriginalCallArgs for these? What if the
3618 // corresponding argument is a list?
3619 PackScope.nextPackElement();
3624 // Build argument packs for each of the parameter packs expanded by this
3626 if (auto Result = PackScope.finish())
3630 return FinishTemplateArgumentDeduction(
3631 FunctionTemplate, Deduced, NumExplicitlySpecified, Specialization, Info,
3632 &OriginalCallArgs, PartialOverloading,
3633 [&]() { return CheckNonDependent(ParamTypesForArgChecking); });
3636 QualType Sema::adjustCCAndNoReturn(QualType ArgFunctionType,
3637 QualType FunctionType,
3638 bool AdjustExceptionSpec) {
3639 if (ArgFunctionType.isNull())
3640 return ArgFunctionType;
3642 const FunctionProtoType *FunctionTypeP =
3643 FunctionType->castAs<FunctionProtoType>();
3644 const FunctionProtoType *ArgFunctionTypeP =
3645 ArgFunctionType->getAs<FunctionProtoType>();
3647 FunctionProtoType::ExtProtoInfo EPI = ArgFunctionTypeP->getExtProtoInfo();
3648 bool Rebuild = false;
3650 CallingConv CC = FunctionTypeP->getCallConv();
3651 if (EPI.ExtInfo.getCC() != CC) {
3652 EPI.ExtInfo = EPI.ExtInfo.withCallingConv(CC);
3656 bool NoReturn = FunctionTypeP->getNoReturnAttr();
3657 if (EPI.ExtInfo.getNoReturn() != NoReturn) {
3658 EPI.ExtInfo = EPI.ExtInfo.withNoReturn(NoReturn);
3662 if (AdjustExceptionSpec && (FunctionTypeP->hasExceptionSpec() ||
3663 ArgFunctionTypeP->hasExceptionSpec())) {
3664 EPI.ExceptionSpec = FunctionTypeP->getExtProtoInfo().ExceptionSpec;
3669 return ArgFunctionType;
3671 return Context.getFunctionType(ArgFunctionTypeP->getReturnType(),
3672 ArgFunctionTypeP->getParamTypes(), EPI);
3675 /// \brief Deduce template arguments when taking the address of a function
3676 /// template (C++ [temp.deduct.funcaddr]) or matching a specialization to
3679 /// \param FunctionTemplate the function template for which we are performing
3680 /// template argument deduction.
3682 /// \param ExplicitTemplateArgs the explicitly-specified template
3685 /// \param ArgFunctionType the function type that will be used as the
3686 /// "argument" type (A) when performing template argument deduction from the
3687 /// function template's function type. This type may be NULL, if there is no
3688 /// argument type to compare against, in C++0x [temp.arg.explicit]p3.
3690 /// \param Specialization if template argument deduction was successful,
3691 /// this will be set to the function template specialization produced by
3692 /// template argument deduction.
3694 /// \param Info the argument will be updated to provide additional information
3695 /// about template argument deduction.
3697 /// \param IsAddressOfFunction If \c true, we are deducing as part of taking
3698 /// the address of a function template per [temp.deduct.funcaddr] and
3699 /// [over.over]. If \c false, we are looking up a function template
3700 /// specialization based on its signature, per [temp.deduct.decl].
3702 /// \returns the result of template argument deduction.
3703 Sema::TemplateDeductionResult Sema::DeduceTemplateArguments(
3704 FunctionTemplateDecl *FunctionTemplate,
3705 TemplateArgumentListInfo *ExplicitTemplateArgs, QualType ArgFunctionType,
3706 FunctionDecl *&Specialization, TemplateDeductionInfo &Info,
3707 bool IsAddressOfFunction) {
3708 if (FunctionTemplate->isInvalidDecl())
3711 FunctionDecl *Function = FunctionTemplate->getTemplatedDecl();
3712 TemplateParameterList *TemplateParams
3713 = FunctionTemplate->getTemplateParameters();
3714 QualType FunctionType = Function->getType();
3716 // When taking the address of a function, we require convertibility of
3717 // the resulting function type. Otherwise, we allow arbitrary mismatches
3718 // of calling convention, noreturn, and noexcept.
3719 if (!IsAddressOfFunction)
3720 ArgFunctionType = adjustCCAndNoReturn(ArgFunctionType, FunctionType,
3721 /*AdjustExceptionSpec*/true);
3723 // Substitute any explicit template arguments.
3724 LocalInstantiationScope InstScope(*this);
3725 SmallVector<DeducedTemplateArgument, 4> Deduced;
3726 unsigned NumExplicitlySpecified = 0;
3727 SmallVector<QualType, 4> ParamTypes;
3728 if (ExplicitTemplateArgs) {
3729 if (TemplateDeductionResult Result
3730 = SubstituteExplicitTemplateArguments(FunctionTemplate,
3731 *ExplicitTemplateArgs,
3732 Deduced, ParamTypes,
3733 &FunctionType, Info))
3736 NumExplicitlySpecified = Deduced.size();
3739 // Unevaluated SFINAE context.
3740 EnterExpressionEvaluationContext Unevaluated(
3741 *this, Sema::ExpressionEvaluationContext::Unevaluated);
3742 SFINAETrap Trap(*this);
3744 Deduced.resize(TemplateParams->size());
3746 // If the function has a deduced return type, substitute it for a dependent
3747 // type so that we treat it as a non-deduced context in what follows. If we
3748 // are looking up by signature, the signature type should also have a deduced
3749 // return type, which we instead expect to exactly match.
3750 bool HasDeducedReturnType = false;
3751 if (getLangOpts().CPlusPlus14 && IsAddressOfFunction &&
3752 Function->getReturnType()->getContainedAutoType()) {
3753 FunctionType = SubstAutoType(FunctionType, Context.DependentTy);
3754 HasDeducedReturnType = true;
3757 if (!ArgFunctionType.isNull()) {
3758 unsigned TDF = TDF_TopLevelParameterTypeList;
3759 if (IsAddressOfFunction)
3760 TDF |= TDF_InOverloadResolution;
3761 // Deduce template arguments from the function type.
3762 if (TemplateDeductionResult Result
3763 = DeduceTemplateArgumentsByTypeMatch(*this, TemplateParams,
3764 FunctionType, ArgFunctionType,
3765 Info, Deduced, TDF))
3769 if (TemplateDeductionResult Result
3770 = FinishTemplateArgumentDeduction(FunctionTemplate, Deduced,
3771 NumExplicitlySpecified,
3772 Specialization, Info))
3775 // If the function has a deduced return type, deduce it now, so we can check
3776 // that the deduced function type matches the requested type.
3777 if (HasDeducedReturnType &&
3778 Specialization->getReturnType()->isUndeducedType() &&
3779 DeduceReturnType(Specialization, Info.getLocation(), false))
3780 return TDK_MiscellaneousDeductionFailure;
3782 // If the function has a dependent exception specification, resolve it now,
3783 // so we can check that the exception specification matches.
3784 auto *SpecializationFPT =
3785 Specialization->getType()->castAs<FunctionProtoType>();
3786 if (getLangOpts().CPlusPlus1z &&
3787 isUnresolvedExceptionSpec(SpecializationFPT->getExceptionSpecType()) &&
3788 !ResolveExceptionSpec(Info.getLocation(), SpecializationFPT))
3789 return TDK_MiscellaneousDeductionFailure;
3791 // Adjust the exception specification of the argument again to match the
3792 // substituted and resolved type we just formed. (Calling convention and
3793 // noreturn can't be dependent, so we don't actually need this for them
3795 QualType SpecializationType = Specialization->getType();
3796 if (!IsAddressOfFunction)
3797 ArgFunctionType = adjustCCAndNoReturn(ArgFunctionType, SpecializationType,
3798 /*AdjustExceptionSpec*/true);
3800 // If the requested function type does not match the actual type of the
3801 // specialization with respect to arguments of compatible pointer to function
3802 // types, template argument deduction fails.
3803 if (!ArgFunctionType.isNull()) {
3804 if (IsAddressOfFunction &&
3805 !isSameOrCompatibleFunctionType(
3806 Context.getCanonicalType(SpecializationType),
3807 Context.getCanonicalType(ArgFunctionType)))
3808 return TDK_MiscellaneousDeductionFailure;
3810 if (!IsAddressOfFunction &&
3811 !Context.hasSameType(SpecializationType, ArgFunctionType))
3812 return TDK_MiscellaneousDeductionFailure;
3818 /// \brief Given a function declaration (e.g. a generic lambda conversion
3819 /// function) that contains an 'auto' in its result type, substitute it
3820 /// with TypeToReplaceAutoWith. Be careful to pass in the type you want
3821 /// to replace 'auto' with and not the actual result type you want
3822 /// to set the function to.
3824 SubstAutoWithinFunctionReturnType(FunctionDecl *F,
3825 QualType TypeToReplaceAutoWith, Sema &S) {
3826 assert(!TypeToReplaceAutoWith->getContainedAutoType());
3827 QualType AutoResultType = F->getReturnType();
3828 assert(AutoResultType->getContainedAutoType());
3829 QualType DeducedResultType = S.SubstAutoType(AutoResultType,
3830 TypeToReplaceAutoWith);
3831 S.Context.adjustDeducedFunctionResultType(F, DeducedResultType);
3834 /// \brief Given a specialized conversion operator of a generic lambda
3835 /// create the corresponding specializations of the call operator and
3836 /// the static-invoker. If the return type of the call operator is auto,
3837 /// deduce its return type and check if that matches the
3838 /// return type of the destination function ptr.
3840 static inline Sema::TemplateDeductionResult
3841 SpecializeCorrespondingLambdaCallOperatorAndInvoker(
3842 CXXConversionDecl *ConversionSpecialized,
3843 SmallVectorImpl<DeducedTemplateArgument> &DeducedArguments,
3844 QualType ReturnTypeOfDestFunctionPtr,
3845 TemplateDeductionInfo &TDInfo,
3848 CXXRecordDecl *LambdaClass = ConversionSpecialized->getParent();
3849 assert(LambdaClass && LambdaClass->isGenericLambda());
3851 CXXMethodDecl *CallOpGeneric = LambdaClass->getLambdaCallOperator();
3852 QualType CallOpResultType = CallOpGeneric->getReturnType();
3853 const bool GenericLambdaCallOperatorHasDeducedReturnType =
3854 CallOpResultType->getContainedAutoType();
3856 FunctionTemplateDecl *CallOpTemplate =
3857 CallOpGeneric->getDescribedFunctionTemplate();
3859 FunctionDecl *CallOpSpecialized = nullptr;
3860 // Use the deduced arguments of the conversion function, to specialize our
3861 // generic lambda's call operator.
3862 if (Sema::TemplateDeductionResult Result
3863 = S.FinishTemplateArgumentDeduction(CallOpTemplate,
3865 0, CallOpSpecialized, TDInfo))
3868 // If we need to deduce the return type, do so (instantiates the callop).
3869 if (GenericLambdaCallOperatorHasDeducedReturnType &&
3870 CallOpSpecialized->getReturnType()->isUndeducedType())
3871 S.DeduceReturnType(CallOpSpecialized,
3872 CallOpSpecialized->getPointOfInstantiation(),
3875 // Check to see if the return type of the destination ptr-to-function
3876 // matches the return type of the call operator.
3877 if (!S.Context.hasSameType(CallOpSpecialized->getReturnType(),
3878 ReturnTypeOfDestFunctionPtr))
3879 return Sema::TDK_NonDeducedMismatch;
3880 // Since we have succeeded in matching the source and destination
3881 // ptr-to-functions (now including return type), and have successfully
3882 // specialized our corresponding call operator, we are ready to
3883 // specialize the static invoker with the deduced arguments of our
3885 FunctionDecl *InvokerSpecialized = nullptr;
3886 FunctionTemplateDecl *InvokerTemplate = LambdaClass->
3887 getLambdaStaticInvoker()->getDescribedFunctionTemplate();
3890 Sema::TemplateDeductionResult LLVM_ATTRIBUTE_UNUSED Result =
3892 S.FinishTemplateArgumentDeduction(InvokerTemplate, DeducedArguments, 0,
3893 InvokerSpecialized, TDInfo);
3894 assert(Result == Sema::TDK_Success &&
3895 "If the call operator succeeded so should the invoker!");
3896 // Set the result type to match the corresponding call operator
3897 // specialization's result type.
3898 if (GenericLambdaCallOperatorHasDeducedReturnType &&
3899 InvokerSpecialized->getReturnType()->isUndeducedType()) {
3900 // Be sure to get the type to replace 'auto' with and not
3901 // the full result type of the call op specialization
3902 // to substitute into the 'auto' of the invoker and conversion
3905 // int* (*fp)(int*) = [](auto* a) -> auto* { return a; };
3906 // We don't want to subst 'int*' into 'auto' to get int**.
3908 QualType TypeToReplaceAutoWith = CallOpSpecialized->getReturnType()
3909 ->getContainedAutoType()
3911 SubstAutoWithinFunctionReturnType(InvokerSpecialized,
3912 TypeToReplaceAutoWith, S);
3913 SubstAutoWithinFunctionReturnType(ConversionSpecialized,
3914 TypeToReplaceAutoWith, S);
3917 // Ensure that static invoker doesn't have a const qualifier.
3918 // FIXME: When creating the InvokerTemplate in SemaLambda.cpp
3919 // do not use the CallOperator's TypeSourceInfo which allows
3920 // the const qualifier to leak through.
3921 const FunctionProtoType *InvokerFPT = InvokerSpecialized->
3922 getType().getTypePtr()->castAs<FunctionProtoType>();
3923 FunctionProtoType::ExtProtoInfo EPI = InvokerFPT->getExtProtoInfo();
3925 InvokerSpecialized->setType(S.Context.getFunctionType(
3926 InvokerFPT->getReturnType(), InvokerFPT->getParamTypes(), EPI));
3927 return Sema::TDK_Success;
3929 /// \brief Deduce template arguments for a templated conversion
3930 /// function (C++ [temp.deduct.conv]) and, if successful, produce a
3931 /// conversion function template specialization.
3932 Sema::TemplateDeductionResult
3933 Sema::DeduceTemplateArguments(FunctionTemplateDecl *ConversionTemplate,
3935 CXXConversionDecl *&Specialization,
3936 TemplateDeductionInfo &Info) {
3937 if (ConversionTemplate->isInvalidDecl())
3940 CXXConversionDecl *ConversionGeneric
3941 = cast<CXXConversionDecl>(ConversionTemplate->getTemplatedDecl());
3943 QualType FromType = ConversionGeneric->getConversionType();
3945 // Canonicalize the types for deduction.
3946 QualType P = Context.getCanonicalType(FromType);
3947 QualType A = Context.getCanonicalType(ToType);
3949 // C++0x [temp.deduct.conv]p2:
3950 // If P is a reference type, the type referred to by P is used for
3952 if (const ReferenceType *PRef = P->getAs<ReferenceType>())
3953 P = PRef->getPointeeType();
3955 // C++0x [temp.deduct.conv]p4:
3956 // [...] If A is a reference type, the type referred to by A is used
3957 // for type deduction.
3958 if (const ReferenceType *ARef = A->getAs<ReferenceType>())
3959 A = ARef->getPointeeType().getUnqualifiedType();
3960 // C++ [temp.deduct.conv]p3:
3962 // If A is not a reference type:
3964 assert(!A->isReferenceType() && "Reference types were handled above");
3966 // - If P is an array type, the pointer type produced by the
3967 // array-to-pointer standard conversion (4.2) is used in place
3968 // of P for type deduction; otherwise,
3969 if (P->isArrayType())
3970 P = Context.getArrayDecayedType(P);
3971 // - If P is a function type, the pointer type produced by the
3972 // function-to-pointer standard conversion (4.3) is used in
3973 // place of P for type deduction; otherwise,
3974 else if (P->isFunctionType())
3975 P = Context.getPointerType(P);
3976 // - If P is a cv-qualified type, the top level cv-qualifiers of
3977 // P's type are ignored for type deduction.
3979 P = P.getUnqualifiedType();
3981 // C++0x [temp.deduct.conv]p4:
3982 // If A is a cv-qualified type, the top level cv-qualifiers of A's
3983 // type are ignored for type deduction. If A is a reference type, the type
3984 // referred to by A is used for type deduction.
3985 A = A.getUnqualifiedType();
3988 // Unevaluated SFINAE context.
3989 EnterExpressionEvaluationContext Unevaluated(
3990 *this, Sema::ExpressionEvaluationContext::Unevaluated);
3991 SFINAETrap Trap(*this);
3993 // C++ [temp.deduct.conv]p1:
3994 // Template argument deduction is done by comparing the return
3995 // type of the template conversion function (call it P) with the
3996 // type that is required as the result of the conversion (call it
3997 // A) as described in 14.8.2.4.
3998 TemplateParameterList *TemplateParams
3999 = ConversionTemplate->getTemplateParameters();
4000 SmallVector<DeducedTemplateArgument, 4> Deduced;
4001 Deduced.resize(TemplateParams->size());
4003 // C++0x [temp.deduct.conv]p4:
4004 // In general, the deduction process attempts to find template
4005 // argument values that will make the deduced A identical to
4006 // A. However, there are two cases that allow a difference:
4008 // - If the original A is a reference type, A can be more
4009 // cv-qualified than the deduced A (i.e., the type referred to
4010 // by the reference)
4011 if (ToType->isReferenceType())
4012 TDF |= TDF_ParamWithReferenceType;
4013 // - The deduced A can be another pointer or pointer to member
4014 // type that can be converted to A via a qualification
4017 // (C++0x [temp.deduct.conv]p6 clarifies that this only happens when
4018 // both P and A are pointers or member pointers. In this case, we
4019 // just ignore cv-qualifiers completely).
4020 if ((P->isPointerType() && A->isPointerType()) ||
4021 (P->isMemberPointerType() && A->isMemberPointerType()))
4022 TDF |= TDF_IgnoreQualifiers;
4023 if (TemplateDeductionResult Result
4024 = DeduceTemplateArgumentsByTypeMatch(*this, TemplateParams,
4025 P, A, Info, Deduced, TDF))
4028 // Create an Instantiation Scope for finalizing the operator.
4029 LocalInstantiationScope InstScope(*this);
4030 // Finish template argument deduction.
4031 FunctionDecl *ConversionSpecialized = nullptr;
4032 TemplateDeductionResult Result
4033 = FinishTemplateArgumentDeduction(ConversionTemplate, Deduced, 0,
4034 ConversionSpecialized, Info);
4035 Specialization = cast_or_null<CXXConversionDecl>(ConversionSpecialized);
4037 // If the conversion operator is being invoked on a lambda closure to convert
4038 // to a ptr-to-function, use the deduced arguments from the conversion
4039 // function to specialize the corresponding call operator.
4040 // e.g., int (*fp)(int) = [](auto a) { return a; };
4041 if (Result == TDK_Success && isLambdaConversionOperator(ConversionGeneric)) {
4043 // Get the return type of the destination ptr-to-function we are converting
4044 // to. This is necessary for matching the lambda call operator's return
4045 // type to that of the destination ptr-to-function's return type.
4046 assert(A->isPointerType() &&
4047 "Can only convert from lambda to ptr-to-function");
4048 const FunctionType *ToFunType =
4049 A->getPointeeType().getTypePtr()->getAs<FunctionType>();
4050 const QualType DestFunctionPtrReturnType = ToFunType->getReturnType();
4052 // Create the corresponding specializations of the call operator and
4053 // the static-invoker; and if the return type is auto,
4054 // deduce the return type and check if it matches the
4055 // DestFunctionPtrReturnType.
4057 // auto L = [](auto a) { return f(a); };
4058 // int (*fp)(int) = L;
4059 // char (*fp2)(int) = L; <-- Not OK.
4061 Result = SpecializeCorrespondingLambdaCallOperatorAndInvoker(
4062 Specialization, Deduced, DestFunctionPtrReturnType,
4068 /// \brief Deduce template arguments for a function template when there is
4069 /// nothing to deduce against (C++0x [temp.arg.explicit]p3).
4071 /// \param FunctionTemplate the function template for which we are performing
4072 /// template argument deduction.
4074 /// \param ExplicitTemplateArgs the explicitly-specified template
4077 /// \param Specialization if template argument deduction was successful,
4078 /// this will be set to the function template specialization produced by
4079 /// template argument deduction.
4081 /// \param Info the argument will be updated to provide additional information
4082 /// about template argument deduction.
4084 /// \param IsAddressOfFunction If \c true, we are deducing as part of taking
4085 /// the address of a function template in a context where we do not have a
4086 /// target type, per [over.over]. If \c false, we are looking up a function
4087 /// template specialization based on its signature, which only happens when
4088 /// deducing a function parameter type from an argument that is a template-id
4089 /// naming a function template specialization.
4091 /// \returns the result of template argument deduction.
4092 Sema::TemplateDeductionResult Sema::DeduceTemplateArguments(
4093 FunctionTemplateDecl *FunctionTemplate,
4094 TemplateArgumentListInfo *ExplicitTemplateArgs,
4095 FunctionDecl *&Specialization, TemplateDeductionInfo &Info,
4096 bool IsAddressOfFunction) {
4097 return DeduceTemplateArguments(FunctionTemplate, ExplicitTemplateArgs,
4098 QualType(), Specialization, Info,
4099 IsAddressOfFunction);
4103 /// Substitute the 'auto' specifier or deduced template specialization type
4104 /// specifier within a type for a given replacement type.
4105 class SubstituteDeducedTypeTransform :
4106 public TreeTransform<SubstituteDeducedTypeTransform> {
4107 QualType Replacement;
4110 SubstituteDeducedTypeTransform(Sema &SemaRef, QualType Replacement,
4111 bool UseTypeSugar = true)
4112 : TreeTransform<SubstituteDeducedTypeTransform>(SemaRef),
4113 Replacement(Replacement), UseTypeSugar(UseTypeSugar) {}
4115 QualType TransformDesugared(TypeLocBuilder &TLB, DeducedTypeLoc TL) {
4116 assert(isa<TemplateTypeParmType>(Replacement) &&
4117 "unexpected unsugared replacement kind");
4118 QualType Result = Replacement;
4119 TemplateTypeParmTypeLoc NewTL = TLB.push<TemplateTypeParmTypeLoc>(Result);
4120 NewTL.setNameLoc(TL.getNameLoc());
4124 QualType TransformAutoType(TypeLocBuilder &TLB, AutoTypeLoc TL) {
4125 // If we're building the type pattern to deduce against, don't wrap the
4126 // substituted type in an AutoType. Certain template deduction rules
4127 // apply only when a template type parameter appears directly (and not if
4128 // the parameter is found through desugaring). For instance:
4129 // auto &&lref = lvalue;
4130 // must transform into "rvalue reference to T" not "rvalue reference to
4131 // auto type deduced as T" in order for [temp.deduct.call]p3 to apply.
4133 // FIXME: Is this still necessary?
4135 return TransformDesugared(TLB, TL);
4137 QualType Result = SemaRef.Context.getAutoType(
4138 Replacement, TL.getTypePtr()->getKeyword(), Replacement.isNull());
4139 auto NewTL = TLB.push<AutoTypeLoc>(Result);
4140 NewTL.setNameLoc(TL.getNameLoc());
4144 QualType TransformDeducedTemplateSpecializationType(
4145 TypeLocBuilder &TLB, DeducedTemplateSpecializationTypeLoc TL) {
4147 return TransformDesugared(TLB, TL);
4149 QualType Result = SemaRef.Context.getDeducedTemplateSpecializationType(
4150 TL.getTypePtr()->getTemplateName(),
4151 Replacement, Replacement.isNull());
4152 auto NewTL = TLB.push<DeducedTemplateSpecializationTypeLoc>(Result);
4153 NewTL.setNameLoc(TL.getNameLoc());
4157 ExprResult TransformLambdaExpr(LambdaExpr *E) {
4158 // Lambdas never need to be transformed.
4162 QualType Apply(TypeLoc TL) {
4163 // Create some scratch storage for the transformed type locations.
4164 // FIXME: We're just going to throw this information away. Don't build it.
4166 TLB.reserve(TL.getFullDataSize());
4167 return TransformType(TLB, TL);
4172 Sema::DeduceAutoResult
4173 Sema::DeduceAutoType(TypeSourceInfo *Type, Expr *&Init, QualType &Result,
4174 Optional<unsigned> DependentDeductionDepth) {
4175 return DeduceAutoType(Type->getTypeLoc(), Init, Result,
4176 DependentDeductionDepth);
4179 /// \brief Deduce the type for an auto type-specifier (C++11 [dcl.spec.auto]p6)
4181 /// Note that this is done even if the initializer is dependent. (This is
4182 /// necessary to support partial ordering of templates using 'auto'.)
4183 /// A dependent type will be produced when deducing from a dependent type.
4185 /// \param Type the type pattern using the auto type-specifier.
4186 /// \param Init the initializer for the variable whose type is to be deduced.
4187 /// \param Result if type deduction was successful, this will be set to the
4189 /// \param DependentDeductionDepth Set if we should permit deduction in
4190 /// dependent cases. This is necessary for template partial ordering with
4191 /// 'auto' template parameters. The value specified is the template
4192 /// parameter depth at which we should perform 'auto' deduction.
4193 Sema::DeduceAutoResult
4194 Sema::DeduceAutoType(TypeLoc Type, Expr *&Init, QualType &Result,
4195 Optional<unsigned> DependentDeductionDepth) {
4196 if (Init->getType()->isNonOverloadPlaceholderType()) {
4197 ExprResult NonPlaceholder = CheckPlaceholderExpr(Init);
4198 if (NonPlaceholder.isInvalid())
4199 return DAR_FailedAlreadyDiagnosed;
4200 Init = NonPlaceholder.get();
4203 if (!DependentDeductionDepth &&
4204 (Type.getType()->isDependentType() || Init->isTypeDependent())) {
4205 Result = SubstituteDeducedTypeTransform(*this, QualType()).Apply(Type);
4206 assert(!Result.isNull() && "substituting DependentTy can't fail");
4207 return DAR_Succeeded;
4210 // Find the depth of template parameter to synthesize.
4211 unsigned Depth = DependentDeductionDepth.getValueOr(0);
4213 // If this is a 'decltype(auto)' specifier, do the decltype dance.
4214 // Since 'decltype(auto)' can only occur at the top of the type, we
4215 // don't need to go digging for it.
4216 if (const AutoType *AT = Type.getType()->getAs<AutoType>()) {
4217 if (AT->isDecltypeAuto()) {
4218 if (isa<InitListExpr>(Init)) {
4219 Diag(Init->getLocStart(), diag::err_decltype_auto_initializer_list);
4220 return DAR_FailedAlreadyDiagnosed;
4223 QualType Deduced = BuildDecltypeType(Init, Init->getLocStart(), false);
4224 if (Deduced.isNull())
4225 return DAR_FailedAlreadyDiagnosed;
4226 // FIXME: Support a non-canonical deduced type for 'auto'.
4227 Deduced = Context.getCanonicalType(Deduced);
4228 Result = SubstituteDeducedTypeTransform(*this, Deduced).Apply(Type);
4229 if (Result.isNull())
4230 return DAR_FailedAlreadyDiagnosed;
4231 return DAR_Succeeded;
4232 } else if (!getLangOpts().CPlusPlus) {
4233 if (isa<InitListExpr>(Init)) {
4234 Diag(Init->getLocStart(), diag::err_auto_init_list_from_c);
4235 return DAR_FailedAlreadyDiagnosed;
4240 SourceLocation Loc = Init->getExprLoc();
4242 LocalInstantiationScope InstScope(*this);
4244 // Build template<class TemplParam> void Func(FuncParam);
4245 TemplateTypeParmDecl *TemplParam = TemplateTypeParmDecl::Create(
4246 Context, nullptr, SourceLocation(), Loc, Depth, 0, nullptr, false, false);
4247 QualType TemplArg = QualType(TemplParam->getTypeForDecl(), 0);
4248 NamedDecl *TemplParamPtr = TemplParam;
4249 FixedSizeTemplateParameterListStorage<1, false> TemplateParamsSt(
4250 Loc, Loc, TemplParamPtr, Loc, nullptr);
4252 QualType FuncParam =
4253 SubstituteDeducedTypeTransform(*this, TemplArg, /*UseTypeSugar*/false)
4255 assert(!FuncParam.isNull() &&
4256 "substituting template parameter for 'auto' failed");
4258 // Deduce type of TemplParam in Func(Init)
4259 SmallVector<DeducedTemplateArgument, 1> Deduced;
4262 TemplateDeductionInfo Info(Loc, Depth);
4264 // If deduction failed, don't diagnose if the initializer is dependent; it
4265 // might acquire a matching type in the instantiation.
4266 auto DeductionFailed = [&]() -> DeduceAutoResult {
4267 if (Init->isTypeDependent()) {
4268 Result = SubstituteDeducedTypeTransform(*this, QualType()).Apply(Type);
4269 assert(!Result.isNull() && "substituting DependentTy can't fail");
4270 return DAR_Succeeded;
4275 SmallVector<OriginalCallArg, 4> OriginalCallArgs;
4277 InitListExpr *InitList = dyn_cast<InitListExpr>(Init);
4279 // Notionally, we substitute std::initializer_list<T> for 'auto' and deduce
4280 // against that. Such deduction only succeeds if removing cv-qualifiers and
4281 // references results in std::initializer_list<T>.
4282 if (!Type.getType().getNonReferenceType()->getAs<AutoType>())
4285 for (unsigned i = 0, e = InitList->getNumInits(); i < e; ++i) {
4286 if (DeduceTemplateArgumentsFromCallArgument(
4287 *this, TemplateParamsSt.get(), 0, TemplArg, InitList->getInit(i),
4288 Info, Deduced, OriginalCallArgs, /*Decomposed*/ true,
4289 /*ArgIdx*/ 0, /*TDF*/ 0))
4290 return DeductionFailed();
4293 if (!getLangOpts().CPlusPlus && Init->refersToBitField()) {
4294 Diag(Loc, diag::err_auto_bitfield);
4295 return DAR_FailedAlreadyDiagnosed;
4298 if (DeduceTemplateArgumentsFromCallArgument(
4299 *this, TemplateParamsSt.get(), 0, FuncParam, Init, Info, Deduced,
4300 OriginalCallArgs, /*Decomposed*/ false, /*ArgIdx*/ 0, /*TDF*/ 0))
4301 return DeductionFailed();
4304 // Could be null if somehow 'auto' appears in a non-deduced context.
4305 if (Deduced[0].getKind() != TemplateArgument::Type)
4306 return DeductionFailed();
4308 QualType DeducedType = Deduced[0].getAsType();
4311 DeducedType = BuildStdInitializerList(DeducedType, Loc);
4312 if (DeducedType.isNull())
4313 return DAR_FailedAlreadyDiagnosed;
4316 Result = SubstituteDeducedTypeTransform(*this, DeducedType).Apply(Type);
4317 if (Result.isNull())
4318 return DAR_FailedAlreadyDiagnosed;
4320 // Check that the deduced argument type is compatible with the original
4321 // argument type per C++ [temp.deduct.call]p4.
4322 QualType DeducedA = InitList ? Deduced[0].getAsType() : Result;
4323 for (const OriginalCallArg &OriginalArg : OriginalCallArgs) {
4324 assert((bool)InitList == OriginalArg.DecomposedParam &&
4325 "decomposed non-init-list in auto deduction?");
4326 if (CheckOriginalCallArgDeduction(*this, OriginalArg, DeducedA)) {
4327 Result = QualType();
4328 return DeductionFailed();
4332 return DAR_Succeeded;
4335 QualType Sema::SubstAutoType(QualType TypeWithAuto,
4336 QualType TypeToReplaceAuto) {
4337 if (TypeToReplaceAuto->isDependentType())
4338 TypeToReplaceAuto = QualType();
4339 return SubstituteDeducedTypeTransform(*this, TypeToReplaceAuto)
4340 .TransformType(TypeWithAuto);
4343 TypeSourceInfo *Sema::SubstAutoTypeSourceInfo(TypeSourceInfo *TypeWithAuto,
4344 QualType TypeToReplaceAuto) {
4345 if (TypeToReplaceAuto->isDependentType())
4346 TypeToReplaceAuto = QualType();
4347 return SubstituteDeducedTypeTransform(*this, TypeToReplaceAuto)
4348 .TransformType(TypeWithAuto);
4351 QualType Sema::ReplaceAutoType(QualType TypeWithAuto,
4352 QualType TypeToReplaceAuto) {
4353 return SubstituteDeducedTypeTransform(*this, TypeToReplaceAuto,
4354 /*UseTypeSugar*/ false)
4355 .TransformType(TypeWithAuto);
4358 void Sema::DiagnoseAutoDeductionFailure(VarDecl *VDecl, Expr *Init) {
4359 if (isa<InitListExpr>(Init))
4360 Diag(VDecl->getLocation(),
4361 VDecl->isInitCapture()
4362 ? diag::err_init_capture_deduction_failure_from_init_list
4363 : diag::err_auto_var_deduction_failure_from_init_list)
4364 << VDecl->getDeclName() << VDecl->getType() << Init->getSourceRange();
4366 Diag(VDecl->getLocation(),
4367 VDecl->isInitCapture() ? diag::err_init_capture_deduction_failure
4368 : diag::err_auto_var_deduction_failure)
4369 << VDecl->getDeclName() << VDecl->getType() << Init->getType()
4370 << Init->getSourceRange();
4373 bool Sema::DeduceReturnType(FunctionDecl *FD, SourceLocation Loc,
4375 assert(FD->getReturnType()->isUndeducedType());
4377 if (FD->getTemplateInstantiationPattern())
4378 InstantiateFunctionDefinition(Loc, FD);
4380 bool StillUndeduced = FD->getReturnType()->isUndeducedType();
4381 if (StillUndeduced && Diagnose && !FD->isInvalidDecl()) {
4382 Diag(Loc, diag::err_auto_fn_used_before_defined) << FD;
4383 Diag(FD->getLocation(), diag::note_callee_decl) << FD;
4386 return StillUndeduced;
4389 /// \brief If this is a non-static member function,
4391 AddImplicitObjectParameterType(ASTContext &Context,
4392 CXXMethodDecl *Method,
4393 SmallVectorImpl<QualType> &ArgTypes) {
4394 // C++11 [temp.func.order]p3:
4395 // [...] The new parameter is of type "reference to cv A," where cv are
4396 // the cv-qualifiers of the function template (if any) and A is
4397 // the class of which the function template is a member.
4399 // The standard doesn't say explicitly, but we pick the appropriate kind of
4400 // reference type based on [over.match.funcs]p4.
4401 QualType ArgTy = Context.getTypeDeclType(Method->getParent());
4402 ArgTy = Context.getQualifiedType(ArgTy,
4403 Qualifiers::fromCVRMask(Method->getTypeQualifiers()));
4404 if (Method->getRefQualifier() == RQ_RValue)
4405 ArgTy = Context.getRValueReferenceType(ArgTy);
4407 ArgTy = Context.getLValueReferenceType(ArgTy);
4408 ArgTypes.push_back(ArgTy);
4411 /// \brief Determine whether the function template \p FT1 is at least as
4412 /// specialized as \p FT2.
4413 static bool isAtLeastAsSpecializedAs(Sema &S,
4415 FunctionTemplateDecl *FT1,
4416 FunctionTemplateDecl *FT2,
4417 TemplatePartialOrderingContext TPOC,
4418 unsigned NumCallArguments1) {
4419 FunctionDecl *FD1 = FT1->getTemplatedDecl();
4420 FunctionDecl *FD2 = FT2->getTemplatedDecl();
4421 const FunctionProtoType *Proto1 = FD1->getType()->getAs<FunctionProtoType>();
4422 const FunctionProtoType *Proto2 = FD2->getType()->getAs<FunctionProtoType>();
4424 assert(Proto1 && Proto2 && "Function templates must have prototypes");
4425 TemplateParameterList *TemplateParams = FT2->getTemplateParameters();
4426 SmallVector<DeducedTemplateArgument, 4> Deduced;
4427 Deduced.resize(TemplateParams->size());
4429 // C++0x [temp.deduct.partial]p3:
4430 // The types used to determine the ordering depend on the context in which
4431 // the partial ordering is done:
4432 TemplateDeductionInfo Info(Loc);
4433 SmallVector<QualType, 4> Args2;
4436 // - In the context of a function call, the function parameter types are
4438 CXXMethodDecl *Method1 = dyn_cast<CXXMethodDecl>(FD1);
4439 CXXMethodDecl *Method2 = dyn_cast<CXXMethodDecl>(FD2);
4441 // C++11 [temp.func.order]p3:
4442 // [...] If only one of the function templates is a non-static
4443 // member, that function template is considered to have a new
4444 // first parameter inserted in its function parameter list. The
4445 // new parameter is of type "reference to cv A," where cv are
4446 // the cv-qualifiers of the function template (if any) and A is
4447 // the class of which the function template is a member.
4449 // Note that we interpret this to mean "if one of the function
4450 // templates is a non-static member and the other is a non-member";
4451 // otherwise, the ordering rules for static functions against non-static
4452 // functions don't make any sense.
4454 // C++98/03 doesn't have this provision but we've extended DR532 to cover
4455 // it as wording was broken prior to it.
4456 SmallVector<QualType, 4> Args1;
4458 unsigned NumComparedArguments = NumCallArguments1;
4460 if (!Method2 && Method1 && !Method1->isStatic()) {
4461 // Compare 'this' from Method1 against first parameter from Method2.
4462 AddImplicitObjectParameterType(S.Context, Method1, Args1);
4463 ++NumComparedArguments;
4464 } else if (!Method1 && Method2 && !Method2->isStatic()) {
4465 // Compare 'this' from Method2 against first parameter from Method1.
4466 AddImplicitObjectParameterType(S.Context, Method2, Args2);
4469 Args1.insert(Args1.end(), Proto1->param_type_begin(),
4470 Proto1->param_type_end());
4471 Args2.insert(Args2.end(), Proto2->param_type_begin(),
4472 Proto2->param_type_end());
4474 // C++ [temp.func.order]p5:
4475 // The presence of unused ellipsis and default arguments has no effect on
4476 // the partial ordering of function templates.
4477 if (Args1.size() > NumComparedArguments)
4478 Args1.resize(NumComparedArguments);
4479 if (Args2.size() > NumComparedArguments)
4480 Args2.resize(NumComparedArguments);
4481 if (DeduceTemplateArguments(S, TemplateParams, Args2.data(), Args2.size(),
4482 Args1.data(), Args1.size(), Info, Deduced,
4483 TDF_None, /*PartialOrdering=*/true))
4489 case TPOC_Conversion:
4490 // - In the context of a call to a conversion operator, the return types
4491 // of the conversion function templates are used.
4492 if (DeduceTemplateArgumentsByTypeMatch(
4493 S, TemplateParams, Proto2->getReturnType(), Proto1->getReturnType(),
4494 Info, Deduced, TDF_None,
4495 /*PartialOrdering=*/true))
4500 // - In other contexts (14.6.6.2) the function template's function type
4502 if (DeduceTemplateArgumentsByTypeMatch(S, TemplateParams,
4503 FD2->getType(), FD1->getType(),
4504 Info, Deduced, TDF_None,
4505 /*PartialOrdering=*/true))
4510 // C++0x [temp.deduct.partial]p11:
4511 // In most cases, all template parameters must have values in order for
4512 // deduction to succeed, but for partial ordering purposes a template
4513 // parameter may remain without a value provided it is not used in the
4514 // types being used for partial ordering. [ Note: a template parameter used
4515 // in a non-deduced context is considered used. -end note]
4516 unsigned ArgIdx = 0, NumArgs = Deduced.size();
4517 for (; ArgIdx != NumArgs; ++ArgIdx)
4518 if (Deduced[ArgIdx].isNull())
4521 // FIXME: We fail to implement [temp.deduct.type]p1 along this path. We need
4522 // to substitute the deduced arguments back into the template and check that
4523 // we get the right type.
4525 if (ArgIdx == NumArgs) {
4526 // All template arguments were deduced. FT1 is at least as specialized
4531 // Figure out which template parameters were used.
4532 llvm::SmallBitVector UsedParameters(TemplateParams->size());
4535 for (unsigned I = 0, N = Args2.size(); I != N; ++I)
4536 ::MarkUsedTemplateParameters(S.Context, Args2[I], false,
4537 TemplateParams->getDepth(),
4541 case TPOC_Conversion:
4542 ::MarkUsedTemplateParameters(S.Context, Proto2->getReturnType(), false,
4543 TemplateParams->getDepth(), UsedParameters);
4547 ::MarkUsedTemplateParameters(S.Context, FD2->getType(), false,
4548 TemplateParams->getDepth(),
4553 for (; ArgIdx != NumArgs; ++ArgIdx)
4554 // If this argument had no value deduced but was used in one of the types
4555 // used for partial ordering, then deduction fails.
4556 if (Deduced[ArgIdx].isNull() && UsedParameters[ArgIdx])
4562 /// \brief Determine whether this a function template whose parameter-type-list
4563 /// ends with a function parameter pack.
4564 static bool isVariadicFunctionTemplate(FunctionTemplateDecl *FunTmpl) {
4565 FunctionDecl *Function = FunTmpl->getTemplatedDecl();
4566 unsigned NumParams = Function->getNumParams();
4570 ParmVarDecl *Last = Function->getParamDecl(NumParams - 1);
4571 if (!Last->isParameterPack())
4574 // Make sure that no previous parameter is a parameter pack.
4575 while (--NumParams > 0) {
4576 if (Function->getParamDecl(NumParams - 1)->isParameterPack())
4583 /// \brief Returns the more specialized function template according
4584 /// to the rules of function template partial ordering (C++ [temp.func.order]).
4586 /// \param FT1 the first function template
4588 /// \param FT2 the second function template
4590 /// \param TPOC the context in which we are performing partial ordering of
4591 /// function templates.
4593 /// \param NumCallArguments1 The number of arguments in the call to FT1, used
4594 /// only when \c TPOC is \c TPOC_Call.
4596 /// \param NumCallArguments2 The number of arguments in the call to FT2, used
4597 /// only when \c TPOC is \c TPOC_Call.
4599 /// \returns the more specialized function template. If neither
4600 /// template is more specialized, returns NULL.
4601 FunctionTemplateDecl *
4602 Sema::getMoreSpecializedTemplate(FunctionTemplateDecl *FT1,
4603 FunctionTemplateDecl *FT2,
4605 TemplatePartialOrderingContext TPOC,
4606 unsigned NumCallArguments1,
4607 unsigned NumCallArguments2) {
4608 bool Better1 = isAtLeastAsSpecializedAs(*this, Loc, FT1, FT2, TPOC,
4610 bool Better2 = isAtLeastAsSpecializedAs(*this, Loc, FT2, FT1, TPOC,
4613 if (Better1 != Better2) // We have a clear winner
4614 return Better1 ? FT1 : FT2;
4616 if (!Better1 && !Better2) // Neither is better than the other
4619 // FIXME: This mimics what GCC implements, but doesn't match up with the
4620 // proposed resolution for core issue 692. This area needs to be sorted out,
4621 // but for now we attempt to maintain compatibility.
4622 bool Variadic1 = isVariadicFunctionTemplate(FT1);
4623 bool Variadic2 = isVariadicFunctionTemplate(FT2);
4624 if (Variadic1 != Variadic2)
4625 return Variadic1? FT2 : FT1;
4630 /// \brief Determine if the two templates are equivalent.
4631 static bool isSameTemplate(TemplateDecl *T1, TemplateDecl *T2) {
4638 return T1->getCanonicalDecl() == T2->getCanonicalDecl();
4641 /// \brief Retrieve the most specialized of the given function template
4642 /// specializations.
4644 /// \param SpecBegin the start iterator of the function template
4645 /// specializations that we will be comparing.
4647 /// \param SpecEnd the end iterator of the function template
4648 /// specializations, paired with \p SpecBegin.
4650 /// \param Loc the location where the ambiguity or no-specializations
4651 /// diagnostic should occur.
4653 /// \param NoneDiag partial diagnostic used to diagnose cases where there are
4654 /// no matching candidates.
4656 /// \param AmbigDiag partial diagnostic used to diagnose an ambiguity, if one
4659 /// \param CandidateDiag partial diagnostic used for each function template
4660 /// specialization that is a candidate in the ambiguous ordering. One parameter
4661 /// in this diagnostic should be unbound, which will correspond to the string
4662 /// describing the template arguments for the function template specialization.
4664 /// \returns the most specialized function template specialization, if
4665 /// found. Otherwise, returns SpecEnd.
4666 UnresolvedSetIterator Sema::getMostSpecialized(
4667 UnresolvedSetIterator SpecBegin, UnresolvedSetIterator SpecEnd,
4668 TemplateSpecCandidateSet &FailedCandidates,
4669 SourceLocation Loc, const PartialDiagnostic &NoneDiag,
4670 const PartialDiagnostic &AmbigDiag, const PartialDiagnostic &CandidateDiag,
4671 bool Complain, QualType TargetType) {
4672 if (SpecBegin == SpecEnd) {
4674 Diag(Loc, NoneDiag);
4675 FailedCandidates.NoteCandidates(*this, Loc);
4680 if (SpecBegin + 1 == SpecEnd)
4683 // Find the function template that is better than all of the templates it
4684 // has been compared to.
4685 UnresolvedSetIterator Best = SpecBegin;
4686 FunctionTemplateDecl *BestTemplate
4687 = cast<FunctionDecl>(*Best)->getPrimaryTemplate();
4688 assert(BestTemplate && "Not a function template specialization?");
4689 for (UnresolvedSetIterator I = SpecBegin + 1; I != SpecEnd; ++I) {
4690 FunctionTemplateDecl *Challenger
4691 = cast<FunctionDecl>(*I)->getPrimaryTemplate();
4692 assert(Challenger && "Not a function template specialization?");
4693 if (isSameTemplate(getMoreSpecializedTemplate(BestTemplate, Challenger,
4694 Loc, TPOC_Other, 0, 0),
4697 BestTemplate = Challenger;
4701 // Make sure that the "best" function template is more specialized than all
4703 bool Ambiguous = false;
4704 for (UnresolvedSetIterator I = SpecBegin; I != SpecEnd; ++I) {
4705 FunctionTemplateDecl *Challenger
4706 = cast<FunctionDecl>(*I)->getPrimaryTemplate();
4708 !isSameTemplate(getMoreSpecializedTemplate(BestTemplate, Challenger,
4709 Loc, TPOC_Other, 0, 0),
4717 // We found an answer. Return it.
4721 // Diagnose the ambiguity.
4723 Diag(Loc, AmbigDiag);
4725 // FIXME: Can we order the candidates in some sane way?
4726 for (UnresolvedSetIterator I = SpecBegin; I != SpecEnd; ++I) {
4727 PartialDiagnostic PD = CandidateDiag;
4728 const auto *FD = cast<FunctionDecl>(*I);
4729 PD << FD << getTemplateArgumentBindingsText(
4730 FD->getPrimaryTemplate()->getTemplateParameters(),
4731 *FD->getTemplateSpecializationArgs());
4732 if (!TargetType.isNull())
4733 HandleFunctionTypeMismatch(PD, FD->getType(), TargetType);
4734 Diag((*I)->getLocation(), PD);
4741 /// Determine whether one partial specialization, P1, is at least as
4742 /// specialized than another, P2.
4744 /// \tparam TemplateLikeDecl The kind of P2, which must be a
4745 /// TemplateDecl or {Class,Var}TemplatePartialSpecializationDecl.
4746 /// \param T1 The injected-class-name of P1 (faked for a variable template).
4747 /// \param T2 The injected-class-name of P2 (faked for a variable template).
4748 template<typename TemplateLikeDecl>
4749 static bool isAtLeastAsSpecializedAs(Sema &S, QualType T1, QualType T2,
4750 TemplateLikeDecl *P2,
4751 TemplateDeductionInfo &Info) {
4752 // C++ [temp.class.order]p1:
4753 // For two class template partial specializations, the first is at least as
4754 // specialized as the second if, given the following rewrite to two
4755 // function templates, the first function template is at least as
4756 // specialized as the second according to the ordering rules for function
4757 // templates (14.6.6.2):
4758 // - the first function template has the same template parameters as the
4759 // first partial specialization and has a single function parameter
4760 // whose type is a class template specialization with the template
4761 // arguments of the first partial specialization, and
4762 // - the second function template has the same template parameters as the
4763 // second partial specialization and has a single function parameter
4764 // whose type is a class template specialization with the template
4765 // arguments of the second partial specialization.
4767 // Rather than synthesize function templates, we merely perform the
4768 // equivalent partial ordering by performing deduction directly on
4769 // the template arguments of the class template partial
4770 // specializations. This computation is slightly simpler than the
4771 // general problem of function template partial ordering, because
4772 // class template partial specializations are more constrained. We
4773 // know that every template parameter is deducible from the class
4774 // template partial specialization's template arguments, for
4776 SmallVector<DeducedTemplateArgument, 4> Deduced;
4778 // Determine whether P1 is at least as specialized as P2.
4779 Deduced.resize(P2->getTemplateParameters()->size());
4780 if (DeduceTemplateArgumentsByTypeMatch(S, P2->getTemplateParameters(),
4781 T2, T1, Info, Deduced, TDF_None,
4782 /*PartialOrdering=*/true))
4785 SmallVector<TemplateArgument, 4> DeducedArgs(Deduced.begin(),
4787 Sema::InstantiatingTemplate Inst(S, Info.getLocation(), P2, DeducedArgs,
4789 auto *TST1 = T1->castAs<TemplateSpecializationType>();
4790 if (FinishTemplateArgumentDeduction(
4791 S, P2, /*PartialOrdering=*/true,
4792 TemplateArgumentList(TemplateArgumentList::OnStack,
4793 TST1->template_arguments()),
4800 /// \brief Returns the more specialized class template partial specialization
4801 /// according to the rules of partial ordering of class template partial
4802 /// specializations (C++ [temp.class.order]).
4804 /// \param PS1 the first class template partial specialization
4806 /// \param PS2 the second class template partial specialization
4808 /// \returns the more specialized class template partial specialization. If
4809 /// neither partial specialization is more specialized, returns NULL.
4810 ClassTemplatePartialSpecializationDecl *
4811 Sema::getMoreSpecializedPartialSpecialization(
4812 ClassTemplatePartialSpecializationDecl *PS1,
4813 ClassTemplatePartialSpecializationDecl *PS2,
4814 SourceLocation Loc) {
4815 QualType PT1 = PS1->getInjectedSpecializationType();
4816 QualType PT2 = PS2->getInjectedSpecializationType();
4818 TemplateDeductionInfo Info(Loc);
4819 bool Better1 = isAtLeastAsSpecializedAs(*this, PT1, PT2, PS2, Info);
4820 bool Better2 = isAtLeastAsSpecializedAs(*this, PT2, PT1, PS1, Info);
4822 if (Better1 == Better2)
4825 return Better1 ? PS1 : PS2;
4828 bool Sema::isMoreSpecializedThanPrimary(
4829 ClassTemplatePartialSpecializationDecl *Spec, TemplateDeductionInfo &Info) {
4830 ClassTemplateDecl *Primary = Spec->getSpecializedTemplate();
4831 QualType PrimaryT = Primary->getInjectedClassNameSpecialization();
4832 QualType PartialT = Spec->getInjectedSpecializationType();
4833 if (!isAtLeastAsSpecializedAs(*this, PartialT, PrimaryT, Primary, Info))
4835 if (isAtLeastAsSpecializedAs(*this, PrimaryT, PartialT, Spec, Info)) {
4836 Info.clearSFINAEDiagnostic();
4842 VarTemplatePartialSpecializationDecl *
4843 Sema::getMoreSpecializedPartialSpecialization(
4844 VarTemplatePartialSpecializationDecl *PS1,
4845 VarTemplatePartialSpecializationDecl *PS2, SourceLocation Loc) {
4846 // Pretend the variable template specializations are class template
4847 // specializations and form a fake injected class name type for comparison.
4848 assert(PS1->getSpecializedTemplate() == PS2->getSpecializedTemplate() &&
4849 "the partial specializations being compared should specialize"
4850 " the same template.");
4851 TemplateName Name(PS1->getSpecializedTemplate());
4852 TemplateName CanonTemplate = Context.getCanonicalTemplateName(Name);
4853 QualType PT1 = Context.getTemplateSpecializationType(
4854 CanonTemplate, PS1->getTemplateArgs().asArray());
4855 QualType PT2 = Context.getTemplateSpecializationType(
4856 CanonTemplate, PS2->getTemplateArgs().asArray());
4858 TemplateDeductionInfo Info(Loc);
4859 bool Better1 = isAtLeastAsSpecializedAs(*this, PT1, PT2, PS2, Info);
4860 bool Better2 = isAtLeastAsSpecializedAs(*this, PT2, PT1, PS1, Info);
4862 if (Better1 == Better2)
4865 return Better1 ? PS1 : PS2;
4868 bool Sema::isMoreSpecializedThanPrimary(
4869 VarTemplatePartialSpecializationDecl *Spec, TemplateDeductionInfo &Info) {
4870 TemplateDecl *Primary = Spec->getSpecializedTemplate();
4871 // FIXME: Cache the injected template arguments rather than recomputing
4872 // them for each partial specialization.
4873 SmallVector<TemplateArgument, 8> PrimaryArgs;
4874 Context.getInjectedTemplateArgs(Primary->getTemplateParameters(),
4877 TemplateName CanonTemplate =
4878 Context.getCanonicalTemplateName(TemplateName(Primary));
4879 QualType PrimaryT = Context.getTemplateSpecializationType(
4880 CanonTemplate, PrimaryArgs);
4881 QualType PartialT = Context.getTemplateSpecializationType(
4882 CanonTemplate, Spec->getTemplateArgs().asArray());
4883 if (!isAtLeastAsSpecializedAs(*this, PartialT, PrimaryT, Primary, Info))
4885 if (isAtLeastAsSpecializedAs(*this, PrimaryT, PartialT, Spec, Info)) {
4886 Info.clearSFINAEDiagnostic();
4892 bool Sema::isTemplateTemplateParameterAtLeastAsSpecializedAs(
4893 TemplateParameterList *P, TemplateDecl *AArg, SourceLocation Loc) {
4894 // C++1z [temp.arg.template]p4: (DR 150)
4895 // A template template-parameter P is at least as specialized as a
4896 // template template-argument A if, given the following rewrite to two
4897 // function templates...
4899 // Rather than synthesize function templates, we merely perform the
4900 // equivalent partial ordering by performing deduction directly on
4901 // the template parameter lists of the template template parameters.
4903 // Given an invented class template X with the template parameter list of
4904 // A (including default arguments):
4905 TemplateName X = Context.getCanonicalTemplateName(TemplateName(AArg));
4906 TemplateParameterList *A = AArg->getTemplateParameters();
4908 // - Each function template has a single function parameter whose type is
4909 // a specialization of X with template arguments corresponding to the
4910 // template parameters from the respective function template
4911 SmallVector<TemplateArgument, 8> AArgs;
4912 Context.getInjectedTemplateArgs(A, AArgs);
4914 // Check P's arguments against A's parameter list. This will fill in default
4915 // template arguments as needed. AArgs are already correct by construction.
4916 // We can't just use CheckTemplateIdType because that will expand alias
4918 SmallVector<TemplateArgument, 4> PArgs;
4920 SFINAETrap Trap(*this);
4922 Context.getInjectedTemplateArgs(P, PArgs);
4923 TemplateArgumentListInfo PArgList(P->getLAngleLoc(), P->getRAngleLoc());
4924 for (unsigned I = 0, N = P->size(); I != N; ++I) {
4925 // Unwrap packs that getInjectedTemplateArgs wrapped around pack
4926 // expansions, to form an "as written" argument list.
4927 TemplateArgument Arg = PArgs[I];
4928 if (Arg.getKind() == TemplateArgument::Pack) {
4929 assert(Arg.pack_size() == 1 && Arg.pack_begin()->isPackExpansion());
4930 Arg = *Arg.pack_begin();
4932 PArgList.addArgument(getTrivialTemplateArgumentLoc(
4933 Arg, QualType(), P->getParam(I)->getLocation()));
4937 // C++1z [temp.arg.template]p3:
4938 // If the rewrite produces an invalid type, then P is not at least as
4939 // specialized as A.
4940 if (CheckTemplateArgumentList(AArg, Loc, PArgList, false, PArgs) ||
4941 Trap.hasErrorOccurred())
4945 QualType AType = Context.getTemplateSpecializationType(X, AArgs);
4946 QualType PType = Context.getTemplateSpecializationType(X, PArgs);
4948 // ... the function template corresponding to P is at least as specialized
4949 // as the function template corresponding to A according to the partial
4950 // ordering rules for function templates.
4951 TemplateDeductionInfo Info(Loc, A->getDepth());
4952 return isAtLeastAsSpecializedAs(*this, PType, AType, AArg, Info);
4955 /// \brief Mark the template parameters that are used by the given
4958 MarkUsedTemplateParameters(ASTContext &Ctx,
4962 llvm::SmallBitVector &Used) {
4963 // We can deduce from a pack expansion.
4964 if (const PackExpansionExpr *Expansion = dyn_cast<PackExpansionExpr>(E))
4965 E = Expansion->getPattern();
4967 // Skip through any implicit casts we added while type-checking, and any
4968 // substitutions performed by template alias expansion.
4970 if (const ImplicitCastExpr *ICE = dyn_cast<ImplicitCastExpr>(E))
4971 E = ICE->getSubExpr();
4972 else if (const SubstNonTypeTemplateParmExpr *Subst =
4973 dyn_cast<SubstNonTypeTemplateParmExpr>(E))
4974 E = Subst->getReplacement();
4979 // FIXME: if !OnlyDeduced, we have to walk the whole subexpression to
4980 // find other occurrences of template parameters.
4981 const DeclRefExpr *DRE = dyn_cast<DeclRefExpr>(E);
4985 const NonTypeTemplateParmDecl *NTTP
4986 = dyn_cast<NonTypeTemplateParmDecl>(DRE->getDecl());
4990 if (NTTP->getDepth() == Depth)
4991 Used[NTTP->getIndex()] = true;
4993 // In C++1z mode, additional arguments may be deduced from the type of a
4994 // non-type argument.
4995 if (Ctx.getLangOpts().CPlusPlus1z)
4996 MarkUsedTemplateParameters(Ctx, NTTP->getType(), OnlyDeduced, Depth, Used);
4999 /// \brief Mark the template parameters that are used by the given
5000 /// nested name specifier.
5002 MarkUsedTemplateParameters(ASTContext &Ctx,
5003 NestedNameSpecifier *NNS,
5006 llvm::SmallBitVector &Used) {
5010 MarkUsedTemplateParameters(Ctx, NNS->getPrefix(), OnlyDeduced, Depth,
5012 MarkUsedTemplateParameters(Ctx, QualType(NNS->getAsType(), 0),
5013 OnlyDeduced, Depth, Used);
5016 /// \brief Mark the template parameters that are used by the given
5019 MarkUsedTemplateParameters(ASTContext &Ctx,
5023 llvm::SmallBitVector &Used) {
5024 if (TemplateDecl *Template = Name.getAsTemplateDecl()) {
5025 if (TemplateTemplateParmDecl *TTP
5026 = dyn_cast<TemplateTemplateParmDecl>(Template)) {
5027 if (TTP->getDepth() == Depth)
5028 Used[TTP->getIndex()] = true;
5033 if (QualifiedTemplateName *QTN = Name.getAsQualifiedTemplateName())
5034 MarkUsedTemplateParameters(Ctx, QTN->getQualifier(), OnlyDeduced,
5036 if (DependentTemplateName *DTN = Name.getAsDependentTemplateName())
5037 MarkUsedTemplateParameters(Ctx, DTN->getQualifier(), OnlyDeduced,
5041 /// \brief Mark the template parameters that are used by the given
5044 MarkUsedTemplateParameters(ASTContext &Ctx, QualType T,
5047 llvm::SmallBitVector &Used) {
5051 // Non-dependent types have nothing deducible
5052 if (!T->isDependentType())
5055 T = Ctx.getCanonicalType(T);
5056 switch (T->getTypeClass()) {
5058 MarkUsedTemplateParameters(Ctx,
5059 cast<PointerType>(T)->getPointeeType(),
5065 case Type::BlockPointer:
5066 MarkUsedTemplateParameters(Ctx,
5067 cast<BlockPointerType>(T)->getPointeeType(),
5073 case Type::LValueReference:
5074 case Type::RValueReference:
5075 MarkUsedTemplateParameters(Ctx,
5076 cast<ReferenceType>(T)->getPointeeType(),
5082 case Type::MemberPointer: {
5083 const MemberPointerType *MemPtr = cast<MemberPointerType>(T.getTypePtr());
5084 MarkUsedTemplateParameters(Ctx, MemPtr->getPointeeType(), OnlyDeduced,
5086 MarkUsedTemplateParameters(Ctx, QualType(MemPtr->getClass(), 0),
5087 OnlyDeduced, Depth, Used);
5091 case Type::DependentSizedArray:
5092 MarkUsedTemplateParameters(Ctx,
5093 cast<DependentSizedArrayType>(T)->getSizeExpr(),
5094 OnlyDeduced, Depth, Used);
5095 // Fall through to check the element type
5097 case Type::ConstantArray:
5098 case Type::IncompleteArray:
5099 MarkUsedTemplateParameters(Ctx,
5100 cast<ArrayType>(T)->getElementType(),
5101 OnlyDeduced, Depth, Used);
5105 case Type::ExtVector:
5106 MarkUsedTemplateParameters(Ctx,
5107 cast<VectorType>(T)->getElementType(),
5108 OnlyDeduced, Depth, Used);
5111 case Type::DependentSizedExtVector: {
5112 const DependentSizedExtVectorType *VecType
5113 = cast<DependentSizedExtVectorType>(T);
5114 MarkUsedTemplateParameters(Ctx, VecType->getElementType(), OnlyDeduced,
5116 MarkUsedTemplateParameters(Ctx, VecType->getSizeExpr(), OnlyDeduced,
5121 case Type::FunctionProto: {
5122 const FunctionProtoType *Proto = cast<FunctionProtoType>(T);
5123 MarkUsedTemplateParameters(Ctx, Proto->getReturnType(), OnlyDeduced, Depth,
5125 for (unsigned I = 0, N = Proto->getNumParams(); I != N; ++I)
5126 MarkUsedTemplateParameters(Ctx, Proto->getParamType(I), OnlyDeduced,
5131 case Type::TemplateTypeParm: {
5132 const TemplateTypeParmType *TTP = cast<TemplateTypeParmType>(T);
5133 if (TTP->getDepth() == Depth)
5134 Used[TTP->getIndex()] = true;
5138 case Type::SubstTemplateTypeParmPack: {
5139 const SubstTemplateTypeParmPackType *Subst
5140 = cast<SubstTemplateTypeParmPackType>(T);
5141 MarkUsedTemplateParameters(Ctx,
5142 QualType(Subst->getReplacedParameter(), 0),
5143 OnlyDeduced, Depth, Used);
5144 MarkUsedTemplateParameters(Ctx, Subst->getArgumentPack(),
5145 OnlyDeduced, Depth, Used);
5149 case Type::InjectedClassName:
5150 T = cast<InjectedClassNameType>(T)->getInjectedSpecializationType();
5153 case Type::TemplateSpecialization: {
5154 const TemplateSpecializationType *Spec
5155 = cast<TemplateSpecializationType>(T);
5156 MarkUsedTemplateParameters(Ctx, Spec->getTemplateName(), OnlyDeduced,
5159 // C++0x [temp.deduct.type]p9:
5160 // If the template argument list of P contains a pack expansion that is
5161 // not the last template argument, the entire template argument list is a
5162 // non-deduced context.
5164 hasPackExpansionBeforeEnd(Spec->template_arguments()))
5167 for (unsigned I = 0, N = Spec->getNumArgs(); I != N; ++I)
5168 MarkUsedTemplateParameters(Ctx, Spec->getArg(I), OnlyDeduced, Depth,
5175 MarkUsedTemplateParameters(Ctx,
5176 cast<ComplexType>(T)->getElementType(),
5177 OnlyDeduced, Depth, Used);
5182 MarkUsedTemplateParameters(Ctx,
5183 cast<AtomicType>(T)->getValueType(),
5184 OnlyDeduced, Depth, Used);
5187 case Type::DependentName:
5189 MarkUsedTemplateParameters(Ctx,
5190 cast<DependentNameType>(T)->getQualifier(),
5191 OnlyDeduced, Depth, Used);
5194 case Type::DependentTemplateSpecialization: {
5195 // C++14 [temp.deduct.type]p5:
5196 // The non-deduced contexts are:
5197 // -- The nested-name-specifier of a type that was specified using a
5200 // C++14 [temp.deduct.type]p6:
5201 // When a type name is specified in a way that includes a non-deduced
5202 // context, all of the types that comprise that type name are also
5207 const DependentTemplateSpecializationType *Spec
5208 = cast<DependentTemplateSpecializationType>(T);
5210 MarkUsedTemplateParameters(Ctx, Spec->getQualifier(),
5211 OnlyDeduced, Depth, Used);
5213 for (unsigned I = 0, N = Spec->getNumArgs(); I != N; ++I)
5214 MarkUsedTemplateParameters(Ctx, Spec->getArg(I), OnlyDeduced, Depth,
5221 MarkUsedTemplateParameters(Ctx,
5222 cast<TypeOfType>(T)->getUnderlyingType(),
5223 OnlyDeduced, Depth, Used);
5226 case Type::TypeOfExpr:
5228 MarkUsedTemplateParameters(Ctx,
5229 cast<TypeOfExprType>(T)->getUnderlyingExpr(),
5230 OnlyDeduced, Depth, Used);
5233 case Type::Decltype:
5235 MarkUsedTemplateParameters(Ctx,
5236 cast<DecltypeType>(T)->getUnderlyingExpr(),
5237 OnlyDeduced, Depth, Used);
5240 case Type::UnaryTransform:
5242 MarkUsedTemplateParameters(Ctx,
5243 cast<UnaryTransformType>(T)->getUnderlyingType(),
5244 OnlyDeduced, Depth, Used);
5247 case Type::PackExpansion:
5248 MarkUsedTemplateParameters(Ctx,
5249 cast<PackExpansionType>(T)->getPattern(),
5250 OnlyDeduced, Depth, Used);
5254 case Type::DeducedTemplateSpecialization:
5255 MarkUsedTemplateParameters(Ctx,
5256 cast<DeducedType>(T)->getDeducedType(),
5257 OnlyDeduced, Depth, Used);
5259 // None of these types have any template parameters in them.
5261 case Type::VariableArray:
5262 case Type::FunctionNoProto:
5265 case Type::ObjCInterface:
5266 case Type::ObjCObject:
5267 case Type::ObjCObjectPointer:
5268 case Type::UnresolvedUsing:
5270 #define TYPE(Class, Base)
5271 #define ABSTRACT_TYPE(Class, Base)
5272 #define DEPENDENT_TYPE(Class, Base)
5273 #define NON_CANONICAL_TYPE(Class, Base) case Type::Class:
5274 #include "clang/AST/TypeNodes.def"
5279 /// \brief Mark the template parameters that are used by this
5280 /// template argument.
5282 MarkUsedTemplateParameters(ASTContext &Ctx,
5283 const TemplateArgument &TemplateArg,
5286 llvm::SmallBitVector &Used) {
5287 switch (TemplateArg.getKind()) {
5288 case TemplateArgument::Null:
5289 case TemplateArgument::Integral:
5290 case TemplateArgument::Declaration:
5293 case TemplateArgument::NullPtr:
5294 MarkUsedTemplateParameters(Ctx, TemplateArg.getNullPtrType(), OnlyDeduced,
5298 case TemplateArgument::Type:
5299 MarkUsedTemplateParameters(Ctx, TemplateArg.getAsType(), OnlyDeduced,
5303 case TemplateArgument::Template:
5304 case TemplateArgument::TemplateExpansion:
5305 MarkUsedTemplateParameters(Ctx,
5306 TemplateArg.getAsTemplateOrTemplatePattern(),
5307 OnlyDeduced, Depth, Used);
5310 case TemplateArgument::Expression:
5311 MarkUsedTemplateParameters(Ctx, TemplateArg.getAsExpr(), OnlyDeduced,
5315 case TemplateArgument::Pack:
5316 for (const auto &P : TemplateArg.pack_elements())
5317 MarkUsedTemplateParameters(Ctx, P, OnlyDeduced, Depth, Used);
5322 /// \brief Mark which template parameters can be deduced from a given
5323 /// template argument list.
5325 /// \param TemplateArgs the template argument list from which template
5326 /// parameters will be deduced.
5328 /// \param Used a bit vector whose elements will be set to \c true
5329 /// to indicate when the corresponding template parameter will be
5332 Sema::MarkUsedTemplateParameters(const TemplateArgumentList &TemplateArgs,
5333 bool OnlyDeduced, unsigned Depth,
5334 llvm::SmallBitVector &Used) {
5335 // C++0x [temp.deduct.type]p9:
5336 // If the template argument list of P contains a pack expansion that is not
5337 // the last template argument, the entire template argument list is a
5338 // non-deduced context.
5340 hasPackExpansionBeforeEnd(TemplateArgs.asArray()))
5343 for (unsigned I = 0, N = TemplateArgs.size(); I != N; ++I)
5344 ::MarkUsedTemplateParameters(Context, TemplateArgs[I], OnlyDeduced,
5348 /// \brief Marks all of the template parameters that will be deduced by a
5349 /// call to the given function template.
5350 void Sema::MarkDeducedTemplateParameters(
5351 ASTContext &Ctx, const FunctionTemplateDecl *FunctionTemplate,
5352 llvm::SmallBitVector &Deduced) {
5353 TemplateParameterList *TemplateParams
5354 = FunctionTemplate->getTemplateParameters();
5356 Deduced.resize(TemplateParams->size());
5358 FunctionDecl *Function = FunctionTemplate->getTemplatedDecl();
5359 for (unsigned I = 0, N = Function->getNumParams(); I != N; ++I)
5360 ::MarkUsedTemplateParameters(Ctx, Function->getParamDecl(I)->getType(),
5361 true, TemplateParams->getDepth(), Deduced);
5364 bool hasDeducibleTemplateParameters(Sema &S,
5365 FunctionTemplateDecl *FunctionTemplate,
5367 if (!T->isDependentType())
5370 TemplateParameterList *TemplateParams
5371 = FunctionTemplate->getTemplateParameters();
5372 llvm::SmallBitVector Deduced(TemplateParams->size());
5373 ::MarkUsedTemplateParameters(S.Context, T, true, TemplateParams->getDepth(),
5376 return Deduced.any();