SemaTemplateInstantiate.cpp revision 193326 
1//===------- SemaTemplateInstantiate.cpp - C++ Template Instantiation ------===/
2//
3//                     The LLVM Compiler Infrastructure
4//
5// This file is distributed under the University of Illinois Open Source
6// License. See LICENSE.TXT for details.
7//===----------------------------------------------------------------------===/
8//
9//  This file implements C++ template instantiation.
10//
11//===----------------------------------------------------------------------===/
12
13#include "Sema.h"
14#include "clang/AST/ASTConsumer.h"
15#include "clang/AST/ASTContext.h"
16#include "clang/AST/Expr.h"
17#include "clang/AST/DeclTemplate.h"
18#include "clang/Parse/DeclSpec.h"
19#include "clang/Basic/LangOptions.h"
20#include "llvm/Support/Compiler.h"
21
22using namespace clang;
23
24//===----------------------------------------------------------------------===/
25// Template Instantiation Support
26//===----------------------------------------------------------------------===/
27
28/// \brief Retrieve the template argument list that should be used to
29/// instantiate the given declaration.
30const TemplateArgumentList &
31Sema::getTemplateInstantiationArgs(NamedDecl *D) {
32  if (ClassTemplateSpecializationDecl *Spec
33        = dyn_cast<ClassTemplateSpecializationDecl>(D))
34    return Spec->getTemplateArgs();
35
36  DeclContext *EnclosingTemplateCtx = D->getDeclContext();
37  while (!isa<ClassTemplateSpecializationDecl>(EnclosingTemplateCtx)) {
38    assert(!EnclosingTemplateCtx->isFileContext() &&
39           "Tried to get the instantiation arguments of a non-template");
40    EnclosingTemplateCtx = EnclosingTemplateCtx->getParent();
41  }
42
43  ClassTemplateSpecializationDecl *EnclosingTemplate
44    = cast<ClassTemplateSpecializationDecl>(EnclosingTemplateCtx);
45  return EnclosingTemplate->getTemplateArgs();
46}
47
48Sema::InstantiatingTemplate::
49InstantiatingTemplate(Sema &SemaRef, SourceLocation PointOfInstantiation,
50                      Decl *Entity,
51                      SourceRange InstantiationRange)
52  :  SemaRef(SemaRef) {
53
54  Invalid = CheckInstantiationDepth(PointOfInstantiation,
55                                    InstantiationRange);
56  if (!Invalid) {
57    ActiveTemplateInstantiation Inst;
58    Inst.Kind = ActiveTemplateInstantiation::TemplateInstantiation;
59    Inst.PointOfInstantiation = PointOfInstantiation;
60    Inst.Entity = reinterpret_cast<uintptr_t>(Entity);
61    Inst.TemplateArgs = 0;
62    Inst.NumTemplateArgs = 0;
63    Inst.InstantiationRange = InstantiationRange;
64    SemaRef.ActiveTemplateInstantiations.push_back(Inst);
65    Invalid = false;
66  }
67}
68
69Sema::InstantiatingTemplate::InstantiatingTemplate(Sema &SemaRef,
70                                         SourceLocation PointOfInstantiation,
71                                         TemplateDecl *Template,
72                                         const TemplateArgument *TemplateArgs,
73                                         unsigned NumTemplateArgs,
74                                         SourceRange InstantiationRange)
75  : SemaRef(SemaRef) {
76
77  Invalid = CheckInstantiationDepth(PointOfInstantiation,
78                                    InstantiationRange);
79  if (!Invalid) {
80    ActiveTemplateInstantiation Inst;
81    Inst.Kind
82      = ActiveTemplateInstantiation::DefaultTemplateArgumentInstantiation;
83    Inst.PointOfInstantiation = PointOfInstantiation;
84    Inst.Entity = reinterpret_cast<uintptr_t>(Template);
85    Inst.TemplateArgs = TemplateArgs;
86    Inst.NumTemplateArgs = NumTemplateArgs;
87    Inst.InstantiationRange = InstantiationRange;
88    SemaRef.ActiveTemplateInstantiations.push_back(Inst);
89    Invalid = false;
90  }
91}
92
93void Sema::InstantiatingTemplate::Clear() {
94  if (!Invalid) {
95    SemaRef.ActiveTemplateInstantiations.pop_back();
96    Invalid = true;
97  }
98}
99
100bool Sema::InstantiatingTemplate::CheckInstantiationDepth(
101                                        SourceLocation PointOfInstantiation,
102                                           SourceRange InstantiationRange) {
103  if (SemaRef.ActiveTemplateInstantiations.size()
104       <= SemaRef.getLangOptions().InstantiationDepth)
105    return false;
106
107  SemaRef.Diag(PointOfInstantiation,
108               diag::err_template_recursion_depth_exceeded)
109    << SemaRef.getLangOptions().InstantiationDepth
110    << InstantiationRange;
111  SemaRef.Diag(PointOfInstantiation, diag::note_template_recursion_depth)
112    << SemaRef.getLangOptions().InstantiationDepth;
113  return true;
114}
115
116/// \brief Prints the current instantiation stack through a series of
117/// notes.
118void Sema::PrintInstantiationStack() {
119  for (llvm::SmallVector<ActiveTemplateInstantiation, 16>::reverse_iterator
120         Active = ActiveTemplateInstantiations.rbegin(),
121         ActiveEnd = ActiveTemplateInstantiations.rend();
122       Active != ActiveEnd;
123       ++Active) {
124    switch (Active->Kind) {
125    case ActiveTemplateInstantiation::TemplateInstantiation: {
126      Decl *D = reinterpret_cast<Decl *>(Active->Entity);
127      if (CXXRecordDecl *Record = dyn_cast<CXXRecordDecl>(D)) {
128        unsigned DiagID = diag::note_template_member_class_here;
129        if (isa<ClassTemplateSpecializationDecl>(Record))
130          DiagID = diag::note_template_class_instantiation_here;
131        Diags.Report(FullSourceLoc(Active->PointOfInstantiation, SourceMgr),
132                     DiagID)
133          << Context.getTypeDeclType(Record)
134          << Active->InstantiationRange;
135      } else {
136        FunctionDecl *Function = cast<FunctionDecl>(D);
137        unsigned DiagID = diag::note_template_member_function_here;
138        // FIXME: check for a function template
139        Diags.Report(FullSourceLoc(Active->PointOfInstantiation, SourceMgr),
140                     DiagID)
141          << Function
142          << Active->InstantiationRange;
143      }
144      break;
145    }
146
147    case ActiveTemplateInstantiation::DefaultTemplateArgumentInstantiation: {
148      TemplateDecl *Template = cast<TemplateDecl>((Decl *)Active->Entity);
149      std::string TemplateArgsStr
150        = TemplateSpecializationType::PrintTemplateArgumentList(
151                                                      Active->TemplateArgs,
152                                                      Active->NumTemplateArgs,
153                                                      Context.PrintingPolicy);
154      Diags.Report(FullSourceLoc(Active->PointOfInstantiation, SourceMgr),
155                   diag::note_default_arg_instantiation_here)
156        << (Template->getNameAsString() + TemplateArgsStr)
157        << Active->InstantiationRange;
158      break;
159    }
160    }
161  }
162}
163
164//===----------------------------------------------------------------------===/
165// Template Instantiation for Types
166//===----------------------------------------------------------------------===/
167namespace {
168  class VISIBILITY_HIDDEN TemplateTypeInstantiator {
169    Sema &SemaRef;
170    const TemplateArgumentList &TemplateArgs;
171    SourceLocation Loc;
172    DeclarationName Entity;
173
174  public:
175    TemplateTypeInstantiator(Sema &SemaRef,
176                             const TemplateArgumentList &TemplateArgs,
177                             SourceLocation Loc,
178                             DeclarationName Entity)
179      : SemaRef(SemaRef), TemplateArgs(TemplateArgs),
180        Loc(Loc), Entity(Entity) { }
181
182    QualType operator()(QualType T) const { return Instantiate(T); }
183
184    QualType Instantiate(QualType T) const;
185
186    // Declare instantiate functions for each type.
187#define TYPE(Class, Base)                                       \
188    QualType Instantiate##Class##Type(const Class##Type *T,     \
189                                      unsigned Quals) const;
190#define ABSTRACT_TYPE(Class, Base)
191#include "clang/AST/TypeNodes.def"
192  };
193}
194
195QualType
196TemplateTypeInstantiator::InstantiateExtQualType(const ExtQualType *T,
197                                                 unsigned Quals) const {
198  // FIXME: Implement this
199  assert(false && "Cannot instantiate ExtQualType yet");
200  return QualType();
201}
202
203QualType
204TemplateTypeInstantiator::InstantiateBuiltinType(const BuiltinType *T,
205                                                 unsigned Quals) const {
206  assert(false && "Builtin types are not dependent and cannot be instantiated");
207  return QualType(T, Quals);
208}
209
210QualType
211TemplateTypeInstantiator::
212InstantiateFixedWidthIntType(const FixedWidthIntType *T, unsigned Quals) const {
213  // FIXME: Implement this
214  assert(false && "Cannot instantiate FixedWidthIntType yet");
215  return QualType();
216}
217
218QualType
219TemplateTypeInstantiator::InstantiateComplexType(const ComplexType *T,
220                                                 unsigned Quals) const {
221  // FIXME: Implement this
222  assert(false && "Cannot instantiate ComplexType yet");
223  return QualType();
224}
225
226QualType
227TemplateTypeInstantiator::InstantiatePointerType(const PointerType *T,
228                                                 unsigned Quals) const {
229  QualType PointeeType = Instantiate(T->getPointeeType());
230  if (PointeeType.isNull())
231    return QualType();
232
233  return SemaRef.BuildPointerType(PointeeType, Quals, Loc, Entity);
234}
235
236QualType
237TemplateTypeInstantiator::InstantiateBlockPointerType(const BlockPointerType *T,
238                                                      unsigned Quals) const {
239  // FIXME: Implement this
240  assert(false && "Cannot instantiate BlockPointerType yet");
241  return QualType();
242}
243
244QualType
245TemplateTypeInstantiator::InstantiateLValueReferenceType(
246    const LValueReferenceType *T, unsigned Quals) const {
247  QualType ReferentType = Instantiate(T->getPointeeType());
248  if (ReferentType.isNull())
249    return QualType();
250
251  return SemaRef.BuildReferenceType(ReferentType, true, Quals, Loc, Entity);
252}
253
254QualType
255TemplateTypeInstantiator::InstantiateRValueReferenceType(
256    const RValueReferenceType *T, unsigned Quals) const {
257  QualType ReferentType = Instantiate(T->getPointeeType());
258  if (ReferentType.isNull())
259    return QualType();
260
261  return SemaRef.BuildReferenceType(ReferentType, false, Quals, Loc, Entity);
262}
263
264QualType
265TemplateTypeInstantiator::
266InstantiateMemberPointerType(const MemberPointerType *T,
267                             unsigned Quals) const {
268  // FIXME: Implement this
269  assert(false && "Cannot instantiate MemberPointerType yet");
270  return QualType();
271}
272
273QualType
274TemplateTypeInstantiator::
275InstantiateConstantArrayType(const ConstantArrayType *T,
276                             unsigned Quals) const {
277  QualType ElementType = Instantiate(T->getElementType());
278  if (ElementType.isNull())
279    return ElementType;
280
281  // Build a temporary integer literal to specify the size for
282  // BuildArrayType. Since we have already checked the size as part of
283  // creating the dependent array type in the first place, we know
284  // there aren't any errors. However, we do need to determine what
285  // C++ type to give the size expression.
286  llvm::APInt Size = T->getSize();
287  QualType Types[] = {
288    SemaRef.Context.UnsignedCharTy, SemaRef.Context.UnsignedShortTy,
289    SemaRef.Context.UnsignedIntTy, SemaRef.Context.UnsignedLongTy,
290    SemaRef.Context.UnsignedLongLongTy, SemaRef.Context.UnsignedInt128Ty
291  };
292  const unsigned NumTypes = sizeof(Types) / sizeof(QualType);
293  QualType SizeType;
294  for (unsigned I = 0; I != NumTypes; ++I)
295    if (Size.getBitWidth() == SemaRef.Context.getIntWidth(Types[I])) {
296      SizeType = Types[I];
297      break;
298    }
299
300  if (SizeType.isNull())
301    SizeType = SemaRef.Context.getFixedWidthIntType(Size.getBitWidth(), false);
302
303  IntegerLiteral ArraySize(Size, SizeType, Loc);
304  return SemaRef.BuildArrayType(ElementType, T->getSizeModifier(),
305                                &ArraySize, T->getIndexTypeQualifier(),
306                                Loc, Entity);
307}
308
309QualType
310TemplateTypeInstantiator::
311InstantiateIncompleteArrayType(const IncompleteArrayType *T,
312                               unsigned Quals) const {
313  QualType ElementType = Instantiate(T->getElementType());
314  if (ElementType.isNull())
315    return ElementType;
316
317  return SemaRef.BuildArrayType(ElementType, T->getSizeModifier(),
318                                0, T->getIndexTypeQualifier(),
319                                Loc, Entity);
320}
321
322QualType
323TemplateTypeInstantiator::
324InstantiateVariableArrayType(const VariableArrayType *T,
325                             unsigned Quals) const {
326  // FIXME: Implement this
327  assert(false && "Cannot instantiate VariableArrayType yet");
328  return QualType();
329}
330
331QualType
332TemplateTypeInstantiator::
333InstantiateDependentSizedArrayType(const DependentSizedArrayType *T,
334                                   unsigned Quals) const {
335  Expr *ArraySize = T->getSizeExpr();
336  assert(ArraySize->isValueDependent() &&
337         "dependent sized array types must have value dependent size expr");
338
339  // Instantiate the element type if needed
340  QualType ElementType = T->getElementType();
341  if (ElementType->isDependentType()) {
342    ElementType = Instantiate(ElementType);
343    if (ElementType.isNull())
344      return QualType();
345  }
346
347  // Instantiate the size expression
348  Sema::OwningExprResult InstantiatedArraySize =
349    SemaRef.InstantiateExpr(ArraySize, TemplateArgs);
350  if (InstantiatedArraySize.isInvalid())
351    return QualType();
352
353  return SemaRef.BuildArrayType(ElementType, T->getSizeModifier(),
354                                InstantiatedArraySize.takeAs<Expr>(),
355                                T->getIndexTypeQualifier(), Loc, Entity);
356}
357
358QualType
359TemplateTypeInstantiator::InstantiateVectorType(const VectorType *T,
360                                             unsigned Quals) const {
361  // FIXME: Implement this
362  assert(false && "Cannot instantiate VectorType yet");
363  return QualType();
364}
365
366QualType
367TemplateTypeInstantiator::InstantiateExtVectorType(const ExtVectorType *T,
368                                                   unsigned Quals) const {
369  // FIXME: Implement this
370  assert(false && "Cannot instantiate ExtVectorType yet");
371  return QualType();
372}
373
374QualType
375TemplateTypeInstantiator::
376InstantiateFunctionProtoType(const FunctionProtoType *T,
377                             unsigned Quals) const {
378  QualType ResultType = Instantiate(T->getResultType());
379  if (ResultType.isNull())
380    return ResultType;
381
382  llvm::SmallVector<QualType, 4> ParamTypes;
383  for (FunctionProtoType::arg_type_iterator Param = T->arg_type_begin(),
384                                         ParamEnd = T->arg_type_end();
385       Param != ParamEnd; ++Param) {
386    QualType P = Instantiate(*Param);
387    if (P.isNull())
388      return P;
389
390    ParamTypes.push_back(P);
391  }
392
393  return SemaRef.BuildFunctionType(ResultType, &ParamTypes[0],
394                                   ParamTypes.size(),
395                                   T->isVariadic(), T->getTypeQuals(),
396                                   Loc, Entity);
397}
398
399QualType
400TemplateTypeInstantiator::
401InstantiateFunctionNoProtoType(const FunctionNoProtoType *T,
402                               unsigned Quals) const {
403  assert(false && "Functions without prototypes cannot be dependent.");
404  return QualType();
405}
406
407QualType
408TemplateTypeInstantiator::InstantiateTypedefType(const TypedefType *T,
409                                                 unsigned Quals) const {
410  TypedefDecl *Typedef
411    = cast_or_null<TypedefDecl>(
412                           SemaRef.InstantiateCurrentDeclRef(T->getDecl()));
413  if (!Typedef)
414    return QualType();
415
416  return SemaRef.Context.getTypeDeclType(Typedef);
417}
418
419QualType
420TemplateTypeInstantiator::InstantiateTypeOfExprType(const TypeOfExprType *T,
421                                                    unsigned Quals) const {
422  Sema::OwningExprResult E
423    = SemaRef.InstantiateExpr(T->getUnderlyingExpr(), TemplateArgs);
424  if (E.isInvalid())
425    return QualType();
426
427  return SemaRef.Context.getTypeOfExprType(E.takeAs<Expr>());
428}
429
430QualType
431TemplateTypeInstantiator::InstantiateTypeOfType(const TypeOfType *T,
432                                                unsigned Quals) const {
433  QualType Underlying = Instantiate(T->getUnderlyingType());
434  if (Underlying.isNull())
435    return QualType();
436
437  return SemaRef.Context.getTypeOfType(Underlying);
438}
439
440QualType
441TemplateTypeInstantiator::InstantiateRecordType(const RecordType *T,
442                                                unsigned Quals) const {
443  RecordDecl *Record
444    = cast_or_null<RecordDecl>(SemaRef.InstantiateCurrentDeclRef(T->getDecl()));
445  if (!Record)
446    return QualType();
447
448  return SemaRef.Context.getTypeDeclType(Record);
449}
450
451QualType
452TemplateTypeInstantiator::InstantiateEnumType(const EnumType *T,
453                                              unsigned Quals) const {
454  EnumDecl *Enum
455    = cast_or_null<EnumDecl>(SemaRef.InstantiateCurrentDeclRef(T->getDecl()));
456  if (!Enum)
457    return QualType();
458
459  return SemaRef.Context.getTypeDeclType(Enum);
460}
461
462QualType
463TemplateTypeInstantiator::
464InstantiateTemplateTypeParmType(const TemplateTypeParmType *T,
465                                unsigned Quals) const {
466  if (T->getDepth() == 0) {
467    // Replace the template type parameter with its corresponding
468    // template argument.
469    assert(TemplateArgs[T->getIndex()].getKind() == TemplateArgument::Type &&
470           "Template argument kind mismatch");
471    QualType Result = TemplateArgs[T->getIndex()].getAsType();
472    if (Result.isNull() || !Quals)
473      return Result;
474
475    // C++ [dcl.ref]p1:
476    //   [...] Cv-qualified references are ill-formed except when
477    //   the cv-qualifiers are introduced through the use of a
478    //   typedef (7.1.3) or of a template type argument (14.3), in
479    //   which case the cv-qualifiers are ignored.
480    if (Quals && Result->isReferenceType())
481      Quals = 0;
482
483    return QualType(Result.getTypePtr(), Quals | Result.getCVRQualifiers());
484  }
485
486  // The template type parameter comes from an inner template (e.g.,
487  // the template parameter list of a member template inside the
488  // template we are instantiating). Create a new template type
489  // parameter with the template "level" reduced by one.
490  return SemaRef.Context.getTemplateTypeParmType(T->getDepth() - 1,
491                                                 T->getIndex(),
492                                                 T->getName())
493    .getQualifiedType(Quals);
494}
495
496QualType
497TemplateTypeInstantiator::
498InstantiateTemplateSpecializationType(
499                                  const TemplateSpecializationType *T,
500                                  unsigned Quals) const {
501  llvm::SmallVector<TemplateArgument, 4> InstantiatedTemplateArgs;
502  InstantiatedTemplateArgs.reserve(T->getNumArgs());
503  for (TemplateSpecializationType::iterator Arg = T->begin(), ArgEnd = T->end();
504       Arg != ArgEnd; ++Arg) {
505    switch (Arg->getKind()) {
506    case TemplateArgument::Type: {
507      QualType T = SemaRef.InstantiateType(Arg->getAsType(),
508                                           TemplateArgs,
509                                           Arg->getLocation(),
510                                           DeclarationName());
511      if (T.isNull())
512        return QualType();
513
514      InstantiatedTemplateArgs.push_back(
515                                TemplateArgument(Arg->getLocation(), T));
516      break;
517    }
518
519    case TemplateArgument::Declaration:
520    case TemplateArgument::Integral:
521      InstantiatedTemplateArgs.push_back(*Arg);
522      break;
523
524    case TemplateArgument::Expression:
525      Sema::OwningExprResult E
526        = SemaRef.InstantiateExpr(Arg->getAsExpr(), TemplateArgs);
527      if (E.isInvalid())
528        return QualType();
529      InstantiatedTemplateArgs.push_back(E.takeAs<Expr>());
530      break;
531    }
532  }
533
534  // FIXME: We're missing the locations of the template name, '<', and '>'.
535
536  TemplateName Name = SemaRef.InstantiateTemplateName(T->getTemplateName(),
537                                                      Loc,
538                                                      TemplateArgs);
539
540  return SemaRef.CheckTemplateIdType(Name, Loc, SourceLocation(),
541                                     &InstantiatedTemplateArgs[0],
542                                     InstantiatedTemplateArgs.size(),
543                                     SourceLocation());
544}
545
546QualType
547TemplateTypeInstantiator::
548InstantiateQualifiedNameType(const QualifiedNameType *T,
549                             unsigned Quals) const {
550  // When we instantiated a qualified name type, there's no point in
551  // keeping the qualification around in the instantiated result. So,
552  // just instantiate the named type.
553  return (*this)(T->getNamedType());
554}
555
556QualType
557TemplateTypeInstantiator::
558InstantiateTypenameType(const TypenameType *T, unsigned Quals) const {
559  if (const TemplateSpecializationType *TemplateId = T->getTemplateId()) {
560    // When the typename type refers to a template-id, the template-id
561    // is dependent and has enough information to instantiate the
562    // result of the typename type. Since we don't care about keeping
563    // the spelling of the typename type in template instantiations,
564    // we just instantiate the template-id.
565    return InstantiateTemplateSpecializationType(TemplateId, Quals);
566  }
567
568  NestedNameSpecifier *NNS
569    = SemaRef.InstantiateNestedNameSpecifier(T->getQualifier(),
570                                             SourceRange(Loc),
571                                             TemplateArgs);
572  if (!NNS)
573    return QualType();
574
575  return SemaRef.CheckTypenameType(NNS, *T->getIdentifier(), SourceRange(Loc));
576}
577
578QualType
579TemplateTypeInstantiator::
580InstantiateObjCInterfaceType(const ObjCInterfaceType *T,
581                             unsigned Quals) const {
582  assert(false && "Objective-C types cannot be dependent");
583  return QualType();
584}
585
586QualType
587TemplateTypeInstantiator::
588InstantiateObjCQualifiedInterfaceType(const ObjCQualifiedInterfaceType *T,
589                                      unsigned Quals) const {
590  assert(false && "Objective-C types cannot be dependent");
591  return QualType();
592}
593
594QualType
595TemplateTypeInstantiator::
596InstantiateObjCQualifiedIdType(const ObjCQualifiedIdType *T,
597                               unsigned Quals) const {
598  assert(false && "Objective-C types cannot be dependent");
599  return QualType();
600}
601
602/// \brief The actual implementation of Sema::InstantiateType().
603QualType TemplateTypeInstantiator::Instantiate(QualType T) const {
604  // If T is not a dependent type, there is nothing to do.
605  if (!T->isDependentType())
606    return T;
607
608  switch (T->getTypeClass()) {
609#define TYPE(Class, Base)                                               \
610  case Type::Class:                                                     \
611    return Instantiate##Class##Type(cast<Class##Type>(T.getTypePtr()),  \
612                                    T.getCVRQualifiers());
613#define ABSTRACT_TYPE(Class, Base)
614#include "clang/AST/TypeNodes.def"
615  }
616
617  assert(false && "Not all types have been decoded for instantiation");
618  return QualType();
619}
620
621/// \brief Instantiate the type T with a given set of template arguments.
622///
623/// This routine substitutes the given template arguments into the
624/// type T and produces the instantiated type.
625///
626/// \param T the type into which the template arguments will be
627/// substituted. If this type is not dependent, it will be returned
628/// immediately.
629///
630/// \param TemplateArgs the template arguments that will be
631/// substituted for the top-level template parameters within T.
632///
633/// \param Loc the location in the source code where this substitution
634/// is being performed. It will typically be the location of the
635/// declarator (if we're instantiating the type of some declaration)
636/// or the location of the type in the source code (if, e.g., we're
637/// instantiating the type of a cast expression).
638///
639/// \param Entity the name of the entity associated with a declaration
640/// being instantiated (if any). May be empty to indicate that there
641/// is no such entity (if, e.g., this is a type that occurs as part of
642/// a cast expression) or that the entity has no name (e.g., an
643/// unnamed function parameter).
644///
645/// \returns If the instantiation succeeds, the instantiated
646/// type. Otherwise, produces diagnostics and returns a NULL type.
647QualType Sema::InstantiateType(QualType T,
648                               const TemplateArgumentList &TemplateArgs,
649                               SourceLocation Loc, DeclarationName Entity) {
650  assert(!ActiveTemplateInstantiations.empty() &&
651         "Cannot perform an instantiation without some context on the "
652         "instantiation stack");
653
654  // If T is not a dependent type, there is nothing to do.
655  if (!T->isDependentType())
656    return T;
657
658  TemplateTypeInstantiator Instantiator(*this, TemplateArgs, Loc, Entity);
659  return Instantiator(T);
660}
661
662/// \brief Instantiate the base class specifiers of the given class
663/// template specialization.
664///
665/// Produces a diagnostic and returns true on error, returns false and
666/// attaches the instantiated base classes to the class template
667/// specialization if successful.
668bool
669Sema::InstantiateBaseSpecifiers(CXXRecordDecl *Instantiation,
670                                CXXRecordDecl *Pattern,
671                                const TemplateArgumentList &TemplateArgs) {
672  bool Invalid = false;
673  llvm::SmallVector<CXXBaseSpecifier*, 4> InstantiatedBases;
674  for (ClassTemplateSpecializationDecl::base_class_iterator
675         Base = Pattern->bases_begin(), BaseEnd = Pattern->bases_end();
676       Base != BaseEnd; ++Base) {
677    if (!Base->getType()->isDependentType()) {
678      // FIXME: Allocate via ASTContext
679      InstantiatedBases.push_back(new CXXBaseSpecifier(*Base));
680      continue;
681    }
682
683    QualType BaseType = InstantiateType(Base->getType(),
684                                        TemplateArgs,
685                                        Base->getSourceRange().getBegin(),
686                                        DeclarationName());
687    if (BaseType.isNull()) {
688      Invalid = true;
689      continue;
690    }
691
692    if (CXXBaseSpecifier *InstantiatedBase
693          = CheckBaseSpecifier(Instantiation,
694                               Base->getSourceRange(),
695                               Base->isVirtual(),
696                               Base->getAccessSpecifierAsWritten(),
697                               BaseType,
698                               /*FIXME: Not totally accurate */
699                               Base->getSourceRange().getBegin()))
700      InstantiatedBases.push_back(InstantiatedBase);
701    else
702      Invalid = true;
703  }
704
705  if (!Invalid &&
706      AttachBaseSpecifiers(Instantiation, InstantiatedBases.data(),
707                           InstantiatedBases.size()))
708    Invalid = true;
709
710  return Invalid;
711}
712
713/// \brief Instantiate the definition of a class from a given pattern.
714///
715/// \param PointOfInstantiation The point of instantiation within the
716/// source code.
717///
718/// \param Instantiation is the declaration whose definition is being
719/// instantiated. This will be either a class template specialization
720/// or a member class of a class template specialization.
721///
722/// \param Pattern is the pattern from which the instantiation
723/// occurs. This will be either the declaration of a class template or
724/// the declaration of a member class of a class template.
725///
726/// \param TemplateArgs The template arguments to be substituted into
727/// the pattern.
728///
729/// \returns true if an error occurred, false otherwise.
730bool
731Sema::InstantiateClass(SourceLocation PointOfInstantiation,
732                       CXXRecordDecl *Instantiation, CXXRecordDecl *Pattern,
733                       const TemplateArgumentList &TemplateArgs,
734                       bool ExplicitInstantiation) {
735  bool Invalid = false;
736
737  CXXRecordDecl *PatternDef
738    = cast_or_null<CXXRecordDecl>(Pattern->getDefinition(Context));
739  if (!PatternDef) {
740    if (Pattern == Instantiation->getInstantiatedFromMemberClass()) {
741      Diag(PointOfInstantiation,
742           diag::err_implicit_instantiate_member_undefined)
743        << Context.getTypeDeclType(Instantiation);
744      Diag(Pattern->getLocation(), diag::note_member_of_template_here);
745    } else {
746      Diag(PointOfInstantiation, diag::err_template_instantiate_undefined)
747        << ExplicitInstantiation
748        << Context.getTypeDeclType(Instantiation);
749      Diag(Pattern->getLocation(), diag::note_template_decl_here);
750    }
751    return true;
752  }
753  Pattern = PatternDef;
754
755  InstantiatingTemplate Inst(*this, PointOfInstantiation, Instantiation);
756  if (Inst)
757    return true;
758
759  // Enter the scope of this instantiation. We don't use
760  // PushDeclContext because we don't have a scope.
761  DeclContext *PreviousContext = CurContext;
762  CurContext = Instantiation;
763
764  // Start the definition of this instantiation.
765  Instantiation->startDefinition();
766
767  // Instantiate the base class specifiers.
768  if (InstantiateBaseSpecifiers(Instantiation, Pattern, TemplateArgs))
769    Invalid = true;
770
771  llvm::SmallVector<DeclPtrTy, 4> Fields;
772  for (RecordDecl::decl_iterator Member = Pattern->decls_begin(Context),
773         MemberEnd = Pattern->decls_end(Context);
774       Member != MemberEnd; ++Member) {
775    Decl *NewMember = InstantiateDecl(*Member, Instantiation, TemplateArgs);
776    if (NewMember) {
777      if (NewMember->isInvalidDecl())
778        Invalid = true;
779      else if (FieldDecl *Field = dyn_cast<FieldDecl>(NewMember))
780        Fields.push_back(DeclPtrTy::make(Field));
781    } else {
782      // FIXME: Eventually, a NULL return will mean that one of the
783      // instantiations was a semantic disaster, and we'll want to set Invalid =
784      // true. For now, we expect to skip some members that we can't yet handle.
785    }
786  }
787
788  // Finish checking fields.
789  ActOnFields(0, Instantiation->getLocation(), DeclPtrTy::make(Instantiation),
790              Fields.data(), Fields.size(), SourceLocation(), SourceLocation(),
791              0);
792
793  // Add any implicitly-declared members that we might need.
794  AddImplicitlyDeclaredMembersToClass(Instantiation);
795
796  // Exit the scope of this instantiation.
797  CurContext = PreviousContext;
798
799  if (!Invalid)
800    Consumer.HandleTagDeclDefinition(Instantiation);
801
802  // If this is an explicit instantiation, instantiate our members, too.
803  if (!Invalid && ExplicitInstantiation) {
804    Inst.Clear();
805    InstantiateClassMembers(PointOfInstantiation, Instantiation, TemplateArgs);
806  }
807
808  return Invalid;
809}
810
811bool
812Sema::InstantiateClassTemplateSpecialization(
813                           ClassTemplateSpecializationDecl *ClassTemplateSpec,
814                           bool ExplicitInstantiation) {
815  // Perform the actual instantiation on the canonical declaration.
816  ClassTemplateSpec = cast<ClassTemplateSpecializationDecl>(
817                               Context.getCanonicalDecl(ClassTemplateSpec));
818
819  // We can only instantiate something that hasn't already been
820  // instantiated or specialized. Fail without any diagnostics: our
821  // caller will provide an error message.
822  if (ClassTemplateSpec->getSpecializationKind() != TSK_Undeclared)
823    return true;
824
825  ClassTemplateDecl *Template = ClassTemplateSpec->getSpecializedTemplate();
826  CXXRecordDecl *Pattern = Template->getTemplatedDecl();
827  const TemplateArgumentList *TemplateArgs
828    = &ClassTemplateSpec->getTemplateArgs();
829
830  // Determine whether any class template partial specializations
831  // match the given template arguments.
832  llvm::SmallVector<ClassTemplatePartialSpecializationDecl *, 4> Matched;
833  for (llvm::FoldingSet<ClassTemplatePartialSpecializationDecl>::iterator
834         Partial = Template->getPartialSpecializations().begin(),
835         PartialEnd = Template->getPartialSpecializations().end();
836       Partial != PartialEnd;
837       ++Partial) {
838    if (DeduceTemplateArguments(&*Partial, ClassTemplateSpec->getTemplateArgs()))
839      Matched.push_back(&*Partial);
840  }
841
842  if (Matched.size() == 1) {
843    Pattern = Matched[0];
844    // FIXME: set TemplateArgs to the template arguments of the
845    // partial specialization, instantiated with the deduced template
846    // arguments.
847  } else if (Matched.size() > 1) {
848    // FIXME: Implement partial ordering of class template partial
849    // specializations.
850    Diag(ClassTemplateSpec->getLocation(),
851         diag::unsup_template_partial_spec_ordering);
852  }
853
854  // Note that this is an instantiation.
855  ClassTemplateSpec->setSpecializationKind(
856                        ExplicitInstantiation? TSK_ExplicitInstantiation
857                                             : TSK_ImplicitInstantiation);
858
859  return InstantiateClass(ClassTemplateSpec->getLocation(),
860                          ClassTemplateSpec, Pattern, *TemplateArgs,
861                          ExplicitInstantiation);
862}
863
864/// \brief Instantiate the definitions of all of the member of the
865/// given class, which is an instantiation of a class template or a
866/// member class of a template.
867void
868Sema::InstantiateClassMembers(SourceLocation PointOfInstantiation,
869                              CXXRecordDecl *Instantiation,
870                              const TemplateArgumentList &TemplateArgs) {
871  for (DeclContext::decl_iterator D = Instantiation->decls_begin(Context),
872                               DEnd = Instantiation->decls_end(Context);
873       D != DEnd; ++D) {
874    if (FunctionDecl *Function = dyn_cast<FunctionDecl>(*D)) {
875      if (!Function->getBody(Context))
876        InstantiateFunctionDefinition(PointOfInstantiation, Function);
877    } else if (VarDecl *Var = dyn_cast<VarDecl>(*D)) {
878      const VarDecl *Def = 0;
879      if (!Var->getDefinition(Def))
880        InstantiateVariableDefinition(Var);
881    } else if (CXXRecordDecl *Record = dyn_cast<CXXRecordDecl>(*D)) {
882      if (!Record->isInjectedClassName() && !Record->getDefinition(Context)) {
883        assert(Record->getInstantiatedFromMemberClass() &&
884               "Missing instantiated-from-template information");
885        InstantiateClass(PointOfInstantiation, Record,
886                         Record->getInstantiatedFromMemberClass(),
887                         TemplateArgs, true);
888      }
889    }
890  }
891}
892
893/// \brief Instantiate the definitions of all of the members of the
894/// given class template specialization, which was named as part of an
895/// explicit instantiation.
896void Sema::InstantiateClassTemplateSpecializationMembers(
897                                           SourceLocation PointOfInstantiation,
898                          ClassTemplateSpecializationDecl *ClassTemplateSpec) {
899  // C++0x [temp.explicit]p7:
900  //   An explicit instantiation that names a class template
901  //   specialization is an explicit instantion of the same kind
902  //   (declaration or definition) of each of its members (not
903  //   including members inherited from base classes) that has not
904  //   been previously explicitly specialized in the translation unit
905  //   containing the explicit instantiation, except as described
906  //   below.
907  InstantiateClassMembers(PointOfInstantiation, ClassTemplateSpec,
908                          ClassTemplateSpec->getTemplateArgs());
909}
910
911/// \brief Instantiate a nested-name-specifier.
912NestedNameSpecifier *
913Sema::InstantiateNestedNameSpecifier(NestedNameSpecifier *NNS,
914                                     SourceRange Range,
915                                     const TemplateArgumentList &TemplateArgs) {
916  // Instantiate the prefix of this nested name specifier.
917  NestedNameSpecifier *Prefix = NNS->getPrefix();
918  if (Prefix) {
919    Prefix = InstantiateNestedNameSpecifier(Prefix, Range, TemplateArgs);
920    if (!Prefix)
921      return 0;
922  }
923
924  switch (NNS->getKind()) {
925  case NestedNameSpecifier::Identifier: {
926    assert(Prefix &&
927           "Can't have an identifier nested-name-specifier with no prefix");
928    CXXScopeSpec SS;
929    // FIXME: The source location information is all wrong.
930    SS.setRange(Range);
931    SS.setScopeRep(Prefix);
932    return static_cast<NestedNameSpecifier *>(
933                                 ActOnCXXNestedNameSpecifier(0, SS,
934                                                             Range.getEnd(),
935                                                             Range.getEnd(),
936                                                    *NNS->getAsIdentifier()));
937    break;
938  }
939
940  case NestedNameSpecifier::Namespace:
941  case NestedNameSpecifier::Global:
942    return NNS;
943
944  case NestedNameSpecifier::TypeSpecWithTemplate:
945  case NestedNameSpecifier::TypeSpec: {
946    QualType T = QualType(NNS->getAsType(), 0);
947    if (!T->isDependentType())
948      return NNS;
949
950    T = InstantiateType(T, TemplateArgs, Range.getBegin(), DeclarationName());
951    if (T.isNull())
952      return 0;
953
954    if (T->isRecordType() ||
955        (getLangOptions().CPlusPlus0x && T->isEnumeralType())) {
956      assert(T.getCVRQualifiers() == 0 && "Can't get cv-qualifiers here");
957      return NestedNameSpecifier::Create(Context, Prefix,
958                 NNS->getKind() == NestedNameSpecifier::TypeSpecWithTemplate,
959                                         T.getTypePtr());
960    }
961
962    Diag(Range.getBegin(), diag::err_nested_name_spec_non_tag) << T;
963    return 0;
964  }
965  }
966
967  // Required to silence a GCC warning
968  return 0;
969}
970
971TemplateName
972Sema::InstantiateTemplateName(TemplateName Name, SourceLocation Loc,
973                              const TemplateArgumentList &TemplateArgs) {
974  if (TemplateTemplateParmDecl *TTP
975        = dyn_cast_or_null<TemplateTemplateParmDecl>(
976                                                 Name.getAsTemplateDecl())) {
977    assert(TTP->getDepth() == 0 &&
978           "Cannot reduce depth of a template template parameter");
979    assert(TemplateArgs[TTP->getPosition()].getAsDecl() &&
980           "Wrong kind of template template argument");
981    ClassTemplateDecl *ClassTemplate
982      = dyn_cast<ClassTemplateDecl>(
983                               TemplateArgs[TTP->getPosition()].getAsDecl());
984    assert(ClassTemplate && "Expected a class template");
985    if (QualifiedTemplateName *QTN = Name.getAsQualifiedTemplateName()) {
986      NestedNameSpecifier *NNS
987        = InstantiateNestedNameSpecifier(QTN->getQualifier(),
988                                         /*FIXME=*/SourceRange(Loc),
989                                         TemplateArgs);
990      if (NNS)
991        return Context.getQualifiedTemplateName(NNS,
992                                                QTN->hasTemplateKeyword(),
993                                                ClassTemplate);
994    }
995
996    return TemplateName(ClassTemplate);
997  } else if (DependentTemplateName *DTN = Name.getAsDependentTemplateName()) {
998    NestedNameSpecifier *NNS
999      = InstantiateNestedNameSpecifier(DTN->getQualifier(),
1000                                       /*FIXME=*/SourceRange(Loc),
1001                                       TemplateArgs);
1002
1003    if (!NNS) // FIXME: Not the best recovery strategy.
1004      return Name;
1005
1006    if (NNS->isDependent())
1007      return Context.getDependentTemplateName(NNS, DTN->getName());
1008
1009    // Somewhat redundant with ActOnDependentTemplateName.
1010    CXXScopeSpec SS;
1011    SS.setRange(SourceRange(Loc));
1012    SS.setScopeRep(NNS);
1013    TemplateTy Template;
1014    TemplateNameKind TNK = isTemplateName(*DTN->getName(), 0, Template, &SS);
1015    if (TNK == TNK_Non_template) {
1016      Diag(Loc, diag::err_template_kw_refers_to_non_template)
1017        << DTN->getName();
1018      return Name;
1019    } else if (TNK == TNK_Function_template) {
1020      Diag(Loc, diag::err_template_kw_refers_to_non_template)
1021        << DTN->getName();
1022      return Name;
1023    }
1024
1025    return Template.getAsVal<TemplateName>();
1026  }
1027
1028
1029
1030  // FIXME: Even if we're referring to a Decl that isn't a template template
1031  // parameter, we may need to instantiate the outer contexts of that
1032  // Decl. However, this won't be needed until we implement member templates.
1033  return Name;
1034}
1035