1 //===- SemaTemplate.h - C++ Templates ---------------------------*- C++ -*-===//
2 //
3 // Part of the LLVM Project, under the Apache License v2.0 with LLVM Exceptions.
4 // See https://llvm.org/LICENSE.txt for license information.
5 // SPDX-License-Identifier: Apache-2.0 WITH LLVM-exception
6 //===----------------------------------------------------------------------===//
7 //
8 // This file provides types used in the semantic analysis of C++ templates.
9 //
10 //===----------------------------------------------------------------------===//
11 
12 #ifndef LLVM_CLANG_SEMA_TEMPLATE_H
13 #define LLVM_CLANG_SEMA_TEMPLATE_H
14 
15 #include "clang/AST/DeclTemplate.h"
16 #include "clang/AST/DeclVisitor.h"
17 #include "clang/AST/TemplateBase.h"
18 #include "clang/AST/Type.h"
19 #include "clang/Basic/LLVM.h"
20 #include "clang/Sema/Sema.h"
21 #include "llvm/ADT/ArrayRef.h"
22 #include "llvm/ADT/DenseMap.h"
23 #include "llvm/ADT/PointerUnion.h"
24 #include "llvm/ADT/SmallVector.h"
25 #include <cassert>
26 #include <optional>
27 #include <utility>
28 
29 namespace clang {
30 
31 class ASTContext;
32 class BindingDecl;
33 class CXXMethodDecl;
34 class Decl;
35 class DeclaratorDecl;
36 class DeclContext;
37 class EnumDecl;
38 class FunctionDecl;
39 class NamedDecl;
40 class ParmVarDecl;
41 class TagDecl;
42 class TypedefNameDecl;
43 class TypeSourceInfo;
44 class VarDecl;
45 
46 /// The kind of template substitution being performed.
47 enum class TemplateSubstitutionKind : char {
48   /// We are substituting template parameters for template arguments in order
49   /// to form a template specialization.
50   Specialization,
51   /// We are substituting template parameters for (typically) other template
52   /// parameters in order to rewrite a declaration as a different declaration
53   /// (for example, when forming a deduction guide from a constructor).
54   Rewrite,
55 };
56 
57   /// Data structure that captures multiple levels of template argument
58   /// lists for use in template instantiation.
59   ///
60   /// Multiple levels of template arguments occur when instantiating the
61   /// definitions of member templates. For example:
62   ///
63   /// \code
64   /// template<typename T>
65   /// struct X {
66   ///   template<T Value>
67   ///   struct Y {
68   ///     void f();
69   ///   };
70   /// };
71   /// \endcode
72   ///
73   /// When instantiating X<int>::Y<17>::f, the multi-level template argument
74   /// list will contain a template argument list (int) at depth 0 and a
75   /// template argument list (17) at depth 1.
76   class MultiLevelTemplateArgumentList {
77     /// The template argument list at a certain template depth
78 
79     using ArgList = ArrayRef<TemplateArgument>;
80     struct ArgumentListLevel {
81       llvm::PointerIntPair<Decl *, 1, bool> AssociatedDeclAndFinal;
82       ArgList Args;
83     };
84     using ContainerType = SmallVector<ArgumentListLevel, 4>;
85 
86     using ArgListsIterator = ContainerType::iterator;
87     using ConstArgListsIterator = ContainerType::const_iterator;
88 
89     /// The template argument lists, stored from the innermost template
90     /// argument list (first) to the outermost template argument list (last).
91     ContainerType TemplateArgumentLists;
92 
93     /// The number of outer levels of template arguments that are not
94     /// being substituted.
95     unsigned NumRetainedOuterLevels = 0;
96 
97     /// The kind of substitution described by this argument list.
98     TemplateSubstitutionKind Kind = TemplateSubstitutionKind::Specialization;
99 
100   public:
101     /// Construct an empty set of template argument lists.
102     MultiLevelTemplateArgumentList() = default;
103 
104     /// Construct a single-level template argument list.
105     MultiLevelTemplateArgumentList(Decl *D, ArgList Args, bool Final) {
106       addOuterTemplateArguments(D, Args, Final);
107     }
108 
109     void setKind(TemplateSubstitutionKind K) { Kind = K; }
110 
111     /// Determine the kind of template substitution being performed.
112     TemplateSubstitutionKind getKind() const { return Kind; }
113 
114     /// Determine whether we are rewriting template parameters rather than
115     /// substituting for them. If so, we should not leave references to the
116     /// original template parameters behind.
117     bool isRewrite() const {
118       return Kind == TemplateSubstitutionKind::Rewrite;
119     }
120 
121     /// Determine the number of levels in this template argument
122     /// list.
123     unsigned getNumLevels() const {
124       return TemplateArgumentLists.size() + NumRetainedOuterLevels;
125     }
126 
127     /// Determine the number of substituted levels in this template
128     /// argument list.
129     unsigned getNumSubstitutedLevels() const {
130       return TemplateArgumentLists.size();
131     }
132 
133     // Determine the number of substituted args at 'Depth'.
134     unsigned getNumSubsitutedArgs(unsigned Depth) const {
135       assert(NumRetainedOuterLevels <= Depth && Depth < getNumLevels());
136       return TemplateArgumentLists[getNumLevels() - Depth - 1].Args.size();
137     }
138 
139     unsigned getNumRetainedOuterLevels() const {
140       return NumRetainedOuterLevels;
141     }
142 
143     /// Determine how many of the \p OldDepth outermost template parameter
144     /// lists would be removed by substituting these arguments.
145     unsigned getNewDepth(unsigned OldDepth) const {
146       if (OldDepth < NumRetainedOuterLevels)
147         return OldDepth;
148       if (OldDepth < getNumLevels())
149         return NumRetainedOuterLevels;
150       return OldDepth - TemplateArgumentLists.size();
151     }
152 
153     /// Retrieve the template argument at a given depth and index.
154     const TemplateArgument &operator()(unsigned Depth, unsigned Index) const {
155       assert(NumRetainedOuterLevels <= Depth && Depth < getNumLevels());
156       assert(Index <
157              TemplateArgumentLists[getNumLevels() - Depth - 1].Args.size());
158       return TemplateArgumentLists[getNumLevels() - Depth - 1].Args[Index];
159     }
160 
161     /// A template-like entity which owns the whole pattern being substituted.
162     /// This will usually own a set of template parameters, or in some
163     /// cases might even be a template parameter itself.
164     std::pair<Decl *, bool> getAssociatedDecl(unsigned Depth) const {
165       assert(NumRetainedOuterLevels <= Depth && Depth < getNumLevels());
166       auto AD = TemplateArgumentLists[getNumLevels() - Depth - 1]
167                     .AssociatedDeclAndFinal;
168       return {AD.getPointer(), AD.getInt()};
169     }
170 
171     /// Determine whether there is a non-NULL template argument at the
172     /// given depth and index.
173     ///
174     /// There must exist a template argument list at the given depth.
175     bool hasTemplateArgument(unsigned Depth, unsigned Index) const {
176       assert(Depth < getNumLevels());
177 
178       if (Depth < NumRetainedOuterLevels)
179         return false;
180 
181       if (Index >=
182           TemplateArgumentLists[getNumLevels() - Depth - 1].Args.size())
183         return false;
184 
185       return !(*this)(Depth, Index).isNull();
186     }
187 
188     bool isAnyArgInstantiationDependent() const {
189       for (ArgumentListLevel ListLevel : TemplateArgumentLists)
190         for (const TemplateArgument &TA : ListLevel.Args)
191           if (TA.isInstantiationDependent())
192             return true;
193       return false;
194     }
195 
196     /// Clear out a specific template argument.
197     void setArgument(unsigned Depth, unsigned Index,
198                      TemplateArgument Arg) {
199       assert(NumRetainedOuterLevels <= Depth && Depth < getNumLevels());
200       assert(Index <
201              TemplateArgumentLists[getNumLevels() - Depth - 1].Args.size());
202       const_cast<TemplateArgument &>(
203           TemplateArgumentLists[getNumLevels() - Depth - 1].Args[Index]) = Arg;
204     }
205 
206     /// Add a new outmost level to the multi-level template argument
207     /// list.
208     /// A 'Final' substitution means that Subst* nodes won't be built
209     /// for the replacements.
210     void addOuterTemplateArguments(Decl *AssociatedDecl, ArgList Args,
211                                    bool Final) {
212       assert(!NumRetainedOuterLevels &&
213              "substituted args outside retained args?");
214       assert(getKind() == TemplateSubstitutionKind::Specialization);
215       TemplateArgumentLists.push_back(
216           {{AssociatedDecl ? AssociatedDecl->getCanonicalDecl() : nullptr,
217             Final},
218            Args});
219     }
220 
221     void addOuterTemplateArguments(ArgList Args) {
222       assert(!NumRetainedOuterLevels &&
223              "substituted args outside retained args?");
224       assert(getKind() == TemplateSubstitutionKind::Rewrite);
225       TemplateArgumentLists.push_back({{}, Args});
226     }
227 
228     void addOuterTemplateArguments(std::nullopt_t) {
229       assert(!NumRetainedOuterLevels &&
230              "substituted args outside retained args?");
231       TemplateArgumentLists.push_back({});
232     }
233 
234     /// Replaces the current 'innermost' level with the provided argument list.
235     /// This is useful for type deduction cases where we need to get the entire
236     /// list from the AST, but then add the deduced innermost list.
237     void replaceInnermostTemplateArguments(Decl *AssociatedDecl, ArgList Args) {
238       assert((!TemplateArgumentLists.empty() || NumRetainedOuterLevels) &&
239              "Replacing in an empty list?");
240 
241       if (!TemplateArgumentLists.empty()) {
242         assert((TemplateArgumentLists[0].AssociatedDeclAndFinal.getPointer() ||
243                 TemplateArgumentLists[0].AssociatedDeclAndFinal.getPointer() ==
244                     AssociatedDecl) &&
245                "Trying to change incorrect declaration?");
246         TemplateArgumentLists[0].Args = Args;
247       } else {
248         --NumRetainedOuterLevels;
249         TemplateArgumentLists.push_back(
250             {{AssociatedDecl, /*Final=*/false}, Args});
251       }
252     }
253 
254     /// Add an outermost level that we are not substituting. We have no
255     /// arguments at this level, and do not remove it from the depth of inner
256     /// template parameters that we instantiate.
257     void addOuterRetainedLevel() {
258       ++NumRetainedOuterLevels;
259     }
260     void addOuterRetainedLevels(unsigned Num) {
261       NumRetainedOuterLevels += Num;
262     }
263 
264     /// Retrieve the innermost template argument list.
265     const ArgList &getInnermost() const {
266       return TemplateArgumentLists.front().Args;
267     }
268     /// Retrieve the outermost template argument list.
269     const ArgList &getOutermost() const {
270       return TemplateArgumentLists.back().Args;
271     }
272     ArgListsIterator begin() { return TemplateArgumentLists.begin(); }
273     ConstArgListsIterator begin() const {
274       return TemplateArgumentLists.begin();
275     }
276     ArgListsIterator end() { return TemplateArgumentLists.end(); }
277     ConstArgListsIterator end() const { return TemplateArgumentLists.end(); }
278 
279     LLVM_DUMP_METHOD void dump() const {
280       LangOptions LO;
281       LO.CPlusPlus = true;
282       LO.Bool = true;
283       PrintingPolicy PP(LO);
284       llvm::errs() << "NumRetainedOuterLevels: " << NumRetainedOuterLevels
285                    << "\n";
286       for (unsigned Depth = NumRetainedOuterLevels; Depth < getNumLevels();
287            ++Depth) {
288         llvm::errs() << Depth << ": ";
289         printTemplateArgumentList(
290             llvm::errs(),
291             TemplateArgumentLists[getNumLevels() - Depth - 1].Args, PP);
292         llvm::errs() << "\n";
293       }
294     }
295   };
296 
297   /// The context in which partial ordering of function templates occurs.
298   enum TPOC {
299     /// Partial ordering of function templates for a function call.
300     TPOC_Call,
301 
302     /// Partial ordering of function templates for a call to a
303     /// conversion function.
304     TPOC_Conversion,
305 
306     /// Partial ordering of function templates in other contexts, e.g.,
307     /// taking the address of a function template or matching a function
308     /// template specialization to a function template.
309     TPOC_Other
310   };
311 
312   // This is lame but unavoidable in a world without forward
313   // declarations of enums.  The alternatives are to either pollute
314   // Sema.h (by including this file) or sacrifice type safety (by
315   // making Sema.h declare things as enums).
316   class TemplatePartialOrderingContext {
317     TPOC Value;
318 
319   public:
320     TemplatePartialOrderingContext(TPOC Value) : Value(Value) {}
321 
322     operator TPOC() const { return Value; }
323   };
324 
325   /// Captures a template argument whose value has been deduced
326   /// via c++ template argument deduction.
327   class DeducedTemplateArgument : public TemplateArgument {
328     /// For a non-type template argument, whether the value was
329     /// deduced from an array bound.
330     bool DeducedFromArrayBound = false;
331 
332   public:
333     DeducedTemplateArgument() = default;
334 
335     DeducedTemplateArgument(const TemplateArgument &Arg,
336                             bool DeducedFromArrayBound = false)
337         : TemplateArgument(Arg), DeducedFromArrayBound(DeducedFromArrayBound) {}
338 
339     /// Construct an integral non-type template argument that
340     /// has been deduced, possibly from an array bound.
341     DeducedTemplateArgument(ASTContext &Ctx,
342                             const llvm::APSInt &Value,
343                             QualType ValueType,
344                             bool DeducedFromArrayBound)
345         : TemplateArgument(Ctx, Value, ValueType),
346           DeducedFromArrayBound(DeducedFromArrayBound) {}
347 
348     /// For a non-type template argument, determine whether the
349     /// template argument was deduced from an array bound.
350     bool wasDeducedFromArrayBound() const { return DeducedFromArrayBound; }
351 
352     /// Specify whether the given non-type template argument
353     /// was deduced from an array bound.
354     void setDeducedFromArrayBound(bool Deduced) {
355       DeducedFromArrayBound = Deduced;
356     }
357   };
358 
359   /// A stack-allocated class that identifies which local
360   /// variable declaration instantiations are present in this scope.
361   ///
362   /// A new instance of this class type will be created whenever we
363   /// instantiate a new function declaration, which will have its own
364   /// set of parameter declarations.
365   class LocalInstantiationScope {
366   public:
367     /// A set of declarations.
368     using DeclArgumentPack = SmallVector<VarDecl *, 4>;
369 
370   private:
371     /// Reference to the semantic analysis that is performing
372     /// this template instantiation.
373     Sema &SemaRef;
374 
375     using LocalDeclsMap =
376         llvm::SmallDenseMap<const Decl *,
377                             llvm::PointerUnion<Decl *, DeclArgumentPack *>, 4>;
378 
379     /// A mapping from local declarations that occur
380     /// within a template to their instantiations.
381     ///
382     /// This mapping is used during instantiation to keep track of,
383     /// e.g., function parameter and variable declarations. For example,
384     /// given:
385     ///
386     /// \code
387     ///   template<typename T> T add(T x, T y) { return x + y; }
388     /// \endcode
389     ///
390     /// when we instantiate add<int>, we will introduce a mapping from
391     /// the ParmVarDecl for 'x' that occurs in the template to the
392     /// instantiated ParmVarDecl for 'x'.
393     ///
394     /// For a parameter pack, the local instantiation scope may contain a
395     /// set of instantiated parameters. This is stored as a DeclArgumentPack
396     /// pointer.
397     LocalDeclsMap LocalDecls;
398 
399     /// The set of argument packs we've allocated.
400     SmallVector<DeclArgumentPack *, 1> ArgumentPacks;
401 
402     /// The outer scope, which contains local variable
403     /// definitions from some other instantiation (that may not be
404     /// relevant to this particular scope).
405     LocalInstantiationScope *Outer;
406 
407     /// Whether we have already exited this scope.
408     bool Exited = false;
409 
410     /// Whether to combine this scope with the outer scope, such that
411     /// lookup will search our outer scope.
412     bool CombineWithOuterScope;
413 
414     /// If non-NULL, the template parameter pack that has been
415     /// partially substituted per C++0x [temp.arg.explicit]p9.
416     NamedDecl *PartiallySubstitutedPack = nullptr;
417 
418     /// If \c PartiallySubstitutedPack is non-null, the set of
419     /// explicitly-specified template arguments in that pack.
420     const TemplateArgument *ArgsInPartiallySubstitutedPack;
421 
422     /// If \c PartiallySubstitutedPack, the number of
423     /// explicitly-specified template arguments in
424     /// ArgsInPartiallySubstitutedPack.
425     unsigned NumArgsInPartiallySubstitutedPack;
426 
427   public:
428     LocalInstantiationScope(Sema &SemaRef, bool CombineWithOuterScope = false)
429         : SemaRef(SemaRef), Outer(SemaRef.CurrentInstantiationScope),
430           CombineWithOuterScope(CombineWithOuterScope) {
431       SemaRef.CurrentInstantiationScope = this;
432     }
433 
434     LocalInstantiationScope(const LocalInstantiationScope &) = delete;
435     LocalInstantiationScope &
436     operator=(const LocalInstantiationScope &) = delete;
437 
438     ~LocalInstantiationScope() {
439       Exit();
440     }
441 
442     const Sema &getSema() const { return SemaRef; }
443 
444     /// Exit this local instantiation scope early.
445     void Exit() {
446       if (Exited)
447         return;
448 
449       for (unsigned I = 0, N = ArgumentPacks.size(); I != N; ++I)
450         delete ArgumentPacks[I];
451 
452       SemaRef.CurrentInstantiationScope = Outer;
453       Exited = true;
454     }
455 
456     /// Clone this scope, and all outer scopes, down to the given
457     /// outermost scope.
458     LocalInstantiationScope *cloneScopes(LocalInstantiationScope *Outermost) {
459       if (this == Outermost) return this;
460 
461       // Save the current scope from SemaRef since the LocalInstantiationScope
462       // will overwrite it on construction
463       LocalInstantiationScope *oldScope = SemaRef.CurrentInstantiationScope;
464 
465       LocalInstantiationScope *newScope =
466         new LocalInstantiationScope(SemaRef, CombineWithOuterScope);
467 
468       newScope->Outer = nullptr;
469       if (Outer)
470         newScope->Outer = Outer->cloneScopes(Outermost);
471 
472       newScope->PartiallySubstitutedPack = PartiallySubstitutedPack;
473       newScope->ArgsInPartiallySubstitutedPack = ArgsInPartiallySubstitutedPack;
474       newScope->NumArgsInPartiallySubstitutedPack =
475         NumArgsInPartiallySubstitutedPack;
476 
477       for (LocalDeclsMap::iterator I = LocalDecls.begin(), E = LocalDecls.end();
478            I != E; ++I) {
479         const Decl *D = I->first;
480         llvm::PointerUnion<Decl *, DeclArgumentPack *> &Stored =
481           newScope->LocalDecls[D];
482         if (I->second.is<Decl *>()) {
483           Stored = I->second.get<Decl *>();
484         } else {
485           DeclArgumentPack *OldPack = I->second.get<DeclArgumentPack *>();
486           DeclArgumentPack *NewPack = new DeclArgumentPack(*OldPack);
487           Stored = NewPack;
488           newScope->ArgumentPacks.push_back(NewPack);
489         }
490       }
491       // Restore the saved scope to SemaRef
492       SemaRef.CurrentInstantiationScope = oldScope;
493       return newScope;
494     }
495 
496     /// deletes the given scope, and all outer scopes, down to the
497     /// given outermost scope.
498     static void deleteScopes(LocalInstantiationScope *Scope,
499                              LocalInstantiationScope *Outermost) {
500       while (Scope && Scope != Outermost) {
501         LocalInstantiationScope *Out = Scope->Outer;
502         delete Scope;
503         Scope = Out;
504       }
505     }
506 
507     /// Find the instantiation of the declaration D within the current
508     /// instantiation scope.
509     ///
510     /// \param D The declaration whose instantiation we are searching for.
511     ///
512     /// \returns A pointer to the declaration or argument pack of declarations
513     /// to which the declaration \c D is instantiated, if found. Otherwise,
514     /// returns NULL.
515     llvm::PointerUnion<Decl *, DeclArgumentPack *> *
516     findInstantiationOf(const Decl *D);
517 
518     void InstantiatedLocal(const Decl *D, Decl *Inst);
519     void InstantiatedLocalPackArg(const Decl *D, VarDecl *Inst);
520     void MakeInstantiatedLocalArgPack(const Decl *D);
521 
522     /// Note that the given parameter pack has been partially substituted
523     /// via explicit specification of template arguments
524     /// (C++0x [temp.arg.explicit]p9).
525     ///
526     /// \param Pack The parameter pack, which will always be a template
527     /// parameter pack.
528     ///
529     /// \param ExplicitArgs The explicitly-specified template arguments provided
530     /// for this parameter pack.
531     ///
532     /// \param NumExplicitArgs The number of explicitly-specified template
533     /// arguments provided for this parameter pack.
534     void SetPartiallySubstitutedPack(NamedDecl *Pack,
535                                      const TemplateArgument *ExplicitArgs,
536                                      unsigned NumExplicitArgs);
537 
538     /// Reset the partially-substituted pack when it is no longer of
539     /// interest.
540     void ResetPartiallySubstitutedPack() {
541       assert(PartiallySubstitutedPack && "No partially-substituted pack");
542       PartiallySubstitutedPack = nullptr;
543       ArgsInPartiallySubstitutedPack = nullptr;
544       NumArgsInPartiallySubstitutedPack = 0;
545     }
546 
547     /// Retrieve the partially-substitued template parameter pack.
548     ///
549     /// If there is no partially-substituted parameter pack, returns NULL.
550     NamedDecl *
551     getPartiallySubstitutedPack(const TemplateArgument **ExplicitArgs = nullptr,
552                                 unsigned *NumExplicitArgs = nullptr) const;
553 
554     /// Determine whether D is a pack expansion created in this scope.
555     bool isLocalPackExpansion(const Decl *D);
556   };
557 
558   class TemplateDeclInstantiator
559     : public DeclVisitor<TemplateDeclInstantiator, Decl *>
560   {
561     Sema &SemaRef;
562     Sema::ArgumentPackSubstitutionIndexRAII SubstIndex;
563     DeclContext *Owner;
564     const MultiLevelTemplateArgumentList &TemplateArgs;
565     Sema::LateInstantiatedAttrVec* LateAttrs = nullptr;
566     LocalInstantiationScope *StartingScope = nullptr;
567     bool EvaluateConstraints = true;
568 
569     /// A list of out-of-line class template partial
570     /// specializations that will need to be instantiated after the
571     /// enclosing class's instantiation is complete.
572     SmallVector<std::pair<ClassTemplateDecl *,
573                                 ClassTemplatePartialSpecializationDecl *>, 4>
574       OutOfLinePartialSpecs;
575 
576     /// A list of out-of-line variable template partial
577     /// specializations that will need to be instantiated after the
578     /// enclosing variable's instantiation is complete.
579     /// FIXME: Verify that this is needed.
580     SmallVector<
581         std::pair<VarTemplateDecl *, VarTemplatePartialSpecializationDecl *>, 4>
582     OutOfLineVarPartialSpecs;
583 
584   public:
585     TemplateDeclInstantiator(Sema &SemaRef, DeclContext *Owner,
586                              const MultiLevelTemplateArgumentList &TemplateArgs)
587         : SemaRef(SemaRef),
588           SubstIndex(SemaRef, SemaRef.ArgumentPackSubstitutionIndex),
589           Owner(Owner), TemplateArgs(TemplateArgs) {}
590 
591     void setEvaluateConstraints(bool B) {
592       EvaluateConstraints = B;
593     }
594     bool getEvaluateConstraints() {
595       return EvaluateConstraints;
596     }
597 
598 // Define all the decl visitors using DeclNodes.inc
599 #define DECL(DERIVED, BASE) \
600     Decl *Visit ## DERIVED ## Decl(DERIVED ## Decl *D);
601 #define ABSTRACT_DECL(DECL)
602 
603 // Decls which never appear inside a class or function.
604 #define OBJCCONTAINER(DERIVED, BASE)
605 #define FILESCOPEASM(DERIVED, BASE)
606 #define TOPLEVELSTMT(DERIVED, BASE)
607 #define IMPORT(DERIVED, BASE)
608 #define EXPORT(DERIVED, BASE)
609 #define LINKAGESPEC(DERIVED, BASE)
610 #define OBJCCOMPATIBLEALIAS(DERIVED, BASE)
611 #define OBJCMETHOD(DERIVED, BASE)
612 #define OBJCTYPEPARAM(DERIVED, BASE)
613 #define OBJCIVAR(DERIVED, BASE)
614 #define OBJCPROPERTY(DERIVED, BASE)
615 #define OBJCPROPERTYIMPL(DERIVED, BASE)
616 #define EMPTY(DERIVED, BASE)
617 #define LIFETIMEEXTENDEDTEMPORARY(DERIVED, BASE)
618 
619     // Decls which use special-case instantiation code.
620 #define BLOCK(DERIVED, BASE)
621 #define CAPTURED(DERIVED, BASE)
622 #define IMPLICITPARAM(DERIVED, BASE)
623 
624 #include "clang/AST/DeclNodes.inc"
625 
626     enum class RewriteKind { None, RewriteSpaceshipAsEqualEqual };
627 
628     void adjustForRewrite(RewriteKind RK, FunctionDecl *Orig, QualType &T,
629                           TypeSourceInfo *&TInfo,
630                           DeclarationNameInfo &NameInfo);
631 
632     // A few supplemental visitor functions.
633     Decl *VisitCXXMethodDecl(CXXMethodDecl *D,
634                              TemplateParameterList *TemplateParams,
635                              RewriteKind RK = RewriteKind::None);
636     Decl *VisitFunctionDecl(FunctionDecl *D,
637                             TemplateParameterList *TemplateParams,
638                             RewriteKind RK = RewriteKind::None);
639     Decl *VisitDecl(Decl *D);
640     Decl *VisitVarDecl(VarDecl *D, bool InstantiatingVarTemplate,
641                        ArrayRef<BindingDecl *> *Bindings = nullptr);
642     Decl *VisitBaseUsingDecls(BaseUsingDecl *D, BaseUsingDecl *Inst,
643                               LookupResult *Lookup);
644 
645     // Enable late instantiation of attributes.  Late instantiated attributes
646     // will be stored in LA.
647     void enableLateAttributeInstantiation(Sema::LateInstantiatedAttrVec *LA) {
648       LateAttrs = LA;
649       StartingScope = SemaRef.CurrentInstantiationScope;
650     }
651 
652     // Disable late instantiation of attributes.
653     void disableLateAttributeInstantiation() {
654       LateAttrs = nullptr;
655       StartingScope = nullptr;
656     }
657 
658     LocalInstantiationScope *getStartingScope() const { return StartingScope; }
659 
660     using delayed_partial_spec_iterator = SmallVectorImpl<std::pair<
661       ClassTemplateDecl *, ClassTemplatePartialSpecializationDecl *>>::iterator;
662 
663     using delayed_var_partial_spec_iterator = SmallVectorImpl<std::pair<
664         VarTemplateDecl *, VarTemplatePartialSpecializationDecl *>>::iterator;
665 
666     /// Return an iterator to the beginning of the set of
667     /// "delayed" partial specializations, which must be passed to
668     /// InstantiateClassTemplatePartialSpecialization once the class
669     /// definition has been completed.
670     delayed_partial_spec_iterator delayed_partial_spec_begin() {
671       return OutOfLinePartialSpecs.begin();
672     }
673 
674     delayed_var_partial_spec_iterator delayed_var_partial_spec_begin() {
675       return OutOfLineVarPartialSpecs.begin();
676     }
677 
678     /// Return an iterator to the end of the set of
679     /// "delayed" partial specializations, which must be passed to
680     /// InstantiateClassTemplatePartialSpecialization once the class
681     /// definition has been completed.
682     delayed_partial_spec_iterator delayed_partial_spec_end() {
683       return OutOfLinePartialSpecs.end();
684     }
685 
686     delayed_var_partial_spec_iterator delayed_var_partial_spec_end() {
687       return OutOfLineVarPartialSpecs.end();
688     }
689 
690     // Helper functions for instantiating methods.
691     TypeSourceInfo *SubstFunctionType(FunctionDecl *D,
692                              SmallVectorImpl<ParmVarDecl *> &Params);
693     bool InitFunctionInstantiation(FunctionDecl *New, FunctionDecl *Tmpl);
694     bool InitMethodInstantiation(CXXMethodDecl *New, CXXMethodDecl *Tmpl);
695 
696     bool SubstDefaultedFunction(FunctionDecl *New, FunctionDecl *Tmpl);
697 
698     TemplateParameterList *
699       SubstTemplateParams(TemplateParameterList *List);
700 
701     bool SubstQualifier(const DeclaratorDecl *OldDecl,
702                         DeclaratorDecl *NewDecl);
703     bool SubstQualifier(const TagDecl *OldDecl,
704                         TagDecl *NewDecl);
705 
706     Decl *VisitVarTemplateSpecializationDecl(
707         VarTemplateDecl *VarTemplate, VarDecl *FromVar,
708         const TemplateArgumentListInfo &TemplateArgsInfo,
709         ArrayRef<TemplateArgument> Converted,
710         VarTemplateSpecializationDecl *PrevDecl = nullptr);
711 
712     Decl *InstantiateTypedefNameDecl(TypedefNameDecl *D, bool IsTypeAlias);
713     ClassTemplatePartialSpecializationDecl *
714     InstantiateClassTemplatePartialSpecialization(
715                                               ClassTemplateDecl *ClassTemplate,
716                            ClassTemplatePartialSpecializationDecl *PartialSpec);
717     VarTemplatePartialSpecializationDecl *
718     InstantiateVarTemplatePartialSpecialization(
719         VarTemplateDecl *VarTemplate,
720         VarTemplatePartialSpecializationDecl *PartialSpec);
721     void InstantiateEnumDefinition(EnumDecl *Enum, EnumDecl *Pattern);
722 
723   private:
724     template<typename T>
725     Decl *instantiateUnresolvedUsingDecl(T *D,
726                                          bool InstantiatingPackElement = false);
727   };
728 
729 } // namespace clang
730 
731 #endif // LLVM_CLANG_SEMA_TEMPLATE_H
732