SemaTemplateInstantiateDecl.cpp revision 9060d0e1f3cf3feccdc9022a33b79b4063fe7cd4 
1//===--- SemaTemplateInstantiateDecl.cpp - C++ Template Decl 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 for declarations.
10//
11//===----------------------------------------------------------------------===/
12#include "Sema.h"
13#include "clang/AST/ASTConsumer.h"
14#include "clang/AST/ASTContext.h"
15#include "clang/AST/DeclTemplate.h"
16#include "clang/AST/DeclVisitor.h"
17#include "clang/AST/Expr.h"
18#include "llvm/Support/Compiler.h"
19
20using namespace clang;
21
22namespace {
23  class VISIBILITY_HIDDEN TemplateDeclInstantiator
24    : public DeclVisitor<TemplateDeclInstantiator, Decl *> {
25    Sema &SemaRef;
26    DeclContext *Owner;
27    const TemplateArgumentList &TemplateArgs;
28
29  public:
30    typedef Sema::OwningExprResult OwningExprResult;
31
32    TemplateDeclInstantiator(Sema &SemaRef, DeclContext *Owner,
33                             const TemplateArgumentList &TemplateArgs)
34      : SemaRef(SemaRef), Owner(Owner), TemplateArgs(TemplateArgs) { }
35
36    // FIXME: Once we get closer to completion, replace these manually-written
37    // declarations with automatically-generated ones from
38    // clang/AST/DeclNodes.def.
39    Decl *VisitTranslationUnitDecl(TranslationUnitDecl *D);
40    Decl *VisitNamespaceDecl(NamespaceDecl *D);
41    Decl *VisitTypedefDecl(TypedefDecl *D);
42    Decl *VisitVarDecl(VarDecl *D);
43    Decl *VisitFieldDecl(FieldDecl *D);
44    Decl *VisitStaticAssertDecl(StaticAssertDecl *D);
45    Decl *VisitEnumDecl(EnumDecl *D);
46    Decl *VisitEnumConstantDecl(EnumConstantDecl *D);
47    Decl *VisitFunctionDecl(FunctionDecl *D);
48    Decl *VisitCXXRecordDecl(CXXRecordDecl *D);
49    Decl *VisitCXXMethodDecl(CXXMethodDecl *D);
50    Decl *VisitCXXConstructorDecl(CXXConstructorDecl *D);
51    Decl *VisitCXXDestructorDecl(CXXDestructorDecl *D);
52    Decl *VisitCXXConversionDecl(CXXConversionDecl *D);
53    ParmVarDecl *VisitParmVarDecl(ParmVarDecl *D);
54    Decl *VisitOriginalParmVarDecl(OriginalParmVarDecl *D);
55
56    // Base case. FIXME: Remove once we can instantiate everything.
57    Decl *VisitDecl(Decl *) {
58      assert(false && "Template instantiation of unknown declaration kind!");
59      return 0;
60    }
61
62    // Helper functions for instantiating methods.
63    QualType InstantiateFunctionType(FunctionDecl *D,
64                             llvm::SmallVectorImpl<ParmVarDecl *> &Params);
65    bool InitFunctionInstantiation(FunctionDecl *New, FunctionDecl *Tmpl);
66    bool InitMethodInstantiation(CXXMethodDecl *New, CXXMethodDecl *Tmpl);
67  };
68}
69
70Decl *
71TemplateDeclInstantiator::VisitTranslationUnitDecl(TranslationUnitDecl *D) {
72  assert(false && "Translation units cannot be instantiated");
73  return D;
74}
75
76Decl *
77TemplateDeclInstantiator::VisitNamespaceDecl(NamespaceDecl *D) {
78  assert(false && "Namespaces cannot be instantiated");
79  return D;
80}
81
82Decl *TemplateDeclInstantiator::VisitTypedefDecl(TypedefDecl *D) {
83  bool Invalid = false;
84  QualType T = D->getUnderlyingType();
85  if (T->isDependentType()) {
86    T = SemaRef.InstantiateType(T, TemplateArgs,
87                                D->getLocation(), D->getDeclName());
88    if (T.isNull()) {
89      Invalid = true;
90      T = SemaRef.Context.IntTy;
91    }
92  }
93
94  // Create the new typedef
95  TypedefDecl *Typedef
96    = TypedefDecl::Create(SemaRef.Context, Owner, D->getLocation(),
97                          D->getIdentifier(), T);
98  if (Invalid)
99    Typedef->setInvalidDecl();
100
101  Owner->addDecl(Typedef);
102
103  return Typedef;
104}
105
106Decl *TemplateDeclInstantiator::VisitVarDecl(VarDecl *D) {
107  // Instantiate the type of the declaration
108  QualType T = SemaRef.InstantiateType(D->getType(), TemplateArgs,
109                                       D->getTypeSpecStartLoc(),
110                                       D->getDeclName());
111  if (T.isNull())
112    return 0;
113
114  // Build the instantiated declaration
115  VarDecl *Var = VarDecl::Create(SemaRef.Context, Owner,
116                                 D->getLocation(), D->getIdentifier(),
117                                 T, D->getStorageClass(),
118                                 D->getTypeSpecStartLoc());
119  Var->setThreadSpecified(D->isThreadSpecified());
120  Var->setCXXDirectInitializer(D->hasCXXDirectInitializer());
121  Var->setDeclaredInCondition(D->isDeclaredInCondition());
122
123  // FIXME: In theory, we could have a previous declaration for variables that
124  // are not static data members.
125  bool Redeclaration = false;
126  SemaRef.CheckVariableDeclaration(Var, 0, Redeclaration);
127  Owner->addDecl(Var);
128
129  if (D->getInit()) {
130    OwningExprResult Init
131      = SemaRef.InstantiateExpr(D->getInit(), TemplateArgs);
132    if (Init.isInvalid())
133      Var->setInvalidDecl();
134    else
135      SemaRef.AddInitializerToDecl(Sema::DeclPtrTy::make(Var), move(Init),
136                                   D->hasCXXDirectInitializer());
137  } else {
138    // FIXME: Call ActOnUninitializedDecl? (Not always)
139  }
140
141  return Var;
142}
143
144Decl *TemplateDeclInstantiator::VisitFieldDecl(FieldDecl *D) {
145  bool Invalid = false;
146  QualType T = D->getType();
147  if (T->isDependentType())  {
148    T = SemaRef.InstantiateType(T, TemplateArgs,
149                                D->getLocation(), D->getDeclName());
150    if (!T.isNull() && T->isFunctionType()) {
151      // C++ [temp.arg.type]p3:
152      //   If a declaration acquires a function type through a type
153      //   dependent on a template-parameter and this causes a
154      //   declaration that does not use the syntactic form of a
155      //   function declarator to have function type, the program is
156      //   ill-formed.
157      SemaRef.Diag(D->getLocation(), diag::err_field_instantiates_to_function)
158        << T;
159      T = QualType();
160      Invalid = true;
161    }
162  }
163
164  Expr *BitWidth = D->getBitWidth();
165  if (Invalid)
166    BitWidth = 0;
167  else if (BitWidth) {
168    // The bit-width expression is not potentially evaluated.
169    EnterExpressionEvaluationContext Unevaluated(SemaRef, Action::Unevaluated);
170
171    OwningExprResult InstantiatedBitWidth
172      = SemaRef.InstantiateExpr(BitWidth, TemplateArgs);
173    if (InstantiatedBitWidth.isInvalid()) {
174      Invalid = true;
175      BitWidth = 0;
176    } else
177      BitWidth = InstantiatedBitWidth.takeAs<Expr>();
178  }
179
180  FieldDecl *Field = SemaRef.CheckFieldDecl(D->getDeclName(), T,
181                                            cast<RecordDecl>(Owner),
182                                            D->getLocation(),
183                                            D->isMutable(),
184                                            BitWidth,
185                                            D->getTypeSpecStartLoc(),
186                                            D->getAccess(),
187                                            0);
188  if (Field) {
189    if (Invalid)
190      Field->setInvalidDecl();
191
192    Owner->addDecl(Field);
193  }
194
195  return Field;
196}
197
198Decl *TemplateDeclInstantiator::VisitStaticAssertDecl(StaticAssertDecl *D) {
199  Expr *AssertExpr = D->getAssertExpr();
200
201  // The expression in a static assertion is not potentially evaluated.
202  EnterExpressionEvaluationContext Unevaluated(SemaRef, Action::Unevaluated);
203
204  OwningExprResult InstantiatedAssertExpr
205    = SemaRef.InstantiateExpr(AssertExpr, TemplateArgs);
206  if (InstantiatedAssertExpr.isInvalid())
207    return 0;
208
209  OwningExprResult Message = SemaRef.Clone(D->getMessage());
210  Decl *StaticAssert
211    = SemaRef.ActOnStaticAssertDeclaration(D->getLocation(),
212                                           move(InstantiatedAssertExpr),
213                                           move(Message)).getAs<Decl>();
214  return StaticAssert;
215}
216
217Decl *TemplateDeclInstantiator::VisitEnumDecl(EnumDecl *D) {
218  EnumDecl *Enum = EnumDecl::Create(SemaRef.Context, Owner,
219                                    D->getLocation(), D->getIdentifier(),
220                                    D->getTagKeywordLoc(),
221                                    /*PrevDecl=*/0);
222  Enum->setInstantiationOfMemberEnum(D);
223  Enum->setAccess(D->getAccess());
224  Owner->addDecl(Enum);
225  Enum->startDefinition();
226
227  llvm::SmallVector<Sema::DeclPtrTy, 4> Enumerators;
228
229  EnumConstantDecl *LastEnumConst = 0;
230  for (EnumDecl::enumerator_iterator EC = D->enumerator_begin(),
231         ECEnd = D->enumerator_end();
232       EC != ECEnd; ++EC) {
233    // The specified value for the enumerator.
234    OwningExprResult Value = SemaRef.Owned((Expr *)0);
235    if (Expr *UninstValue = EC->getInitExpr()) {
236      // The enumerator's value expression is not potentially evaluated.
237      EnterExpressionEvaluationContext Unevaluated(SemaRef,
238                                                   Action::Unevaluated);
239
240      Value = SemaRef.InstantiateExpr(UninstValue, TemplateArgs);
241    }
242
243    // Drop the initial value and continue.
244    bool isInvalid = false;
245    if (Value.isInvalid()) {
246      Value = SemaRef.Owned((Expr *)0);
247      isInvalid = true;
248    }
249
250    EnumConstantDecl *EnumConst
251      = SemaRef.CheckEnumConstant(Enum, LastEnumConst,
252                                  EC->getLocation(), EC->getIdentifier(),
253                                  move(Value));
254
255    if (isInvalid) {
256      if (EnumConst)
257        EnumConst->setInvalidDecl();
258      Enum->setInvalidDecl();
259    }
260
261    if (EnumConst) {
262      Enum->addDecl(EnumConst);
263      Enumerators.push_back(Sema::DeclPtrTy::make(EnumConst));
264      LastEnumConst = EnumConst;
265    }
266  }
267
268  // FIXME: Fixup LBraceLoc and RBraceLoc
269  SemaRef.ActOnEnumBody(Enum->getLocation(), SourceLocation(), SourceLocation(),
270                        Sema::DeclPtrTy::make(Enum),
271                        &Enumerators[0], Enumerators.size());
272
273  return Enum;
274}
275
276Decl *TemplateDeclInstantiator::VisitEnumConstantDecl(EnumConstantDecl *D) {
277  assert(false && "EnumConstantDecls can only occur within EnumDecls.");
278  return 0;
279}
280
281Decl *TemplateDeclInstantiator::VisitCXXRecordDecl(CXXRecordDecl *D) {
282  CXXRecordDecl *PrevDecl = 0;
283  if (D->isInjectedClassName())
284    PrevDecl = cast<CXXRecordDecl>(Owner);
285
286  CXXRecordDecl *Record
287    = CXXRecordDecl::Create(SemaRef.Context, D->getTagKind(), Owner,
288                            D->getLocation(), D->getIdentifier(),
289                            D->getTagKeywordLoc(), PrevDecl);
290  Record->setImplicit(D->isImplicit());
291  Record->setAccess(D->getAccess());
292  if (!D->isInjectedClassName())
293    Record->setInstantiationOfMemberClass(D);
294
295  Owner->addDecl(Record);
296  return Record;
297}
298
299Decl *TemplateDeclInstantiator::VisitFunctionDecl(FunctionDecl *D) {
300  // Check whether there is already a function template specialization for
301  // this declaration.
302  FunctionTemplateDecl *FunctionTemplate = D->getDescribedFunctionTemplate();
303  void *InsertPos = 0;
304  if (FunctionTemplate) {
305    llvm::FoldingSetNodeID ID;
306    FunctionTemplateSpecializationInfo::Profile(ID,
307                                          TemplateArgs.getFlatArgumentList(),
308                                                TemplateArgs.flat_size());
309
310    FunctionTemplateSpecializationInfo *Info
311      = FunctionTemplate->getSpecializations().FindNodeOrInsertPos(ID,
312                                                                   InsertPos);
313
314    // If we already have a function template specialization, return it.
315    if (Info)
316      return Info->Function;
317  }
318
319  Sema::LocalInstantiationScope Scope(SemaRef);
320
321  llvm::SmallVector<ParmVarDecl *, 4> Params;
322  QualType T = InstantiateFunctionType(D, Params);
323  if (T.isNull())
324    return 0;
325
326  // Build the instantiated method declaration.
327  FunctionDecl *Function
328    = FunctionDecl::Create(SemaRef.Context, Owner, D->getLocation(),
329                           D->getDeclName(), T, D->getStorageClass(),
330                           D->isInline(), D->hasWrittenPrototype(),
331                           D->getTypeSpecStartLoc());
332
333  // FIXME: friend functions
334
335  // Attach the parameters
336  for (unsigned P = 0; P < Params.size(); ++P)
337    Params[P]->setOwningFunction(Function);
338  Function->setParams(SemaRef.Context, Params.data(), Params.size());
339
340  if (InitFunctionInstantiation(Function, D))
341    Function->setInvalidDecl();
342
343  bool Redeclaration = false;
344  bool OverloadableAttrRequired = false;
345  NamedDecl *PrevDecl = 0;
346  SemaRef.CheckFunctionDeclaration(Function, PrevDecl, Redeclaration,
347                                   /*FIXME:*/OverloadableAttrRequired);
348
349  if (FunctionTemplate) {
350    // Record this function template specialization.
351    Function->setFunctionTemplateSpecialization(SemaRef.Context,
352                                                FunctionTemplate,
353                                                &TemplateArgs,
354                                                InsertPos);
355   }
356
357  return Function;
358}
359
360Decl *TemplateDeclInstantiator::VisitCXXMethodDecl(CXXMethodDecl *D) {
361  // FIXME: Look for existing, explicit specializations.
362  Sema::LocalInstantiationScope Scope(SemaRef);
363
364  llvm::SmallVector<ParmVarDecl *, 4> Params;
365  QualType T = InstantiateFunctionType(D, Params);
366  if (T.isNull())
367    return 0;
368
369  // Build the instantiated method declaration.
370  CXXRecordDecl *Record = cast<CXXRecordDecl>(Owner);
371  CXXMethodDecl *Method
372    = CXXMethodDecl::Create(SemaRef.Context, Record, D->getLocation(),
373                            D->getDeclName(), T, D->isStatic(),
374                            D->isInline());
375  Method->setInstantiationOfMemberFunction(D);
376
377  // Attach the parameters
378  for (unsigned P = 0; P < Params.size(); ++P)
379    Params[P]->setOwningFunction(Method);
380  Method->setParams(SemaRef.Context, Params.data(), Params.size());
381
382  if (InitMethodInstantiation(Method, D))
383    Method->setInvalidDecl();
384
385  NamedDecl *PrevDecl
386    = SemaRef.LookupQualifiedName(Owner, Method->getDeclName(),
387                                  Sema::LookupOrdinaryName, true);
388  // In C++, the previous declaration we find might be a tag type
389  // (class or enum). In this case, the new declaration will hide the
390  // tag type. Note that this does does not apply if we're declaring a
391  // typedef (C++ [dcl.typedef]p4).
392  if (PrevDecl && PrevDecl->getIdentifierNamespace() == Decl::IDNS_Tag)
393    PrevDecl = 0;
394  bool Redeclaration = false;
395  bool OverloadableAttrRequired = false;
396  SemaRef.CheckFunctionDeclaration(Method, PrevDecl, Redeclaration,
397                                   /*FIXME:*/OverloadableAttrRequired);
398
399  if (!Method->isInvalidDecl() || !PrevDecl)
400    Owner->addDecl(Method);
401  return Method;
402}
403
404Decl *TemplateDeclInstantiator::VisitCXXConstructorDecl(CXXConstructorDecl *D) {
405  // FIXME: Look for existing, explicit specializations.
406  Sema::LocalInstantiationScope Scope(SemaRef);
407
408  llvm::SmallVector<ParmVarDecl *, 4> Params;
409  QualType T = InstantiateFunctionType(D, Params);
410  if (T.isNull())
411    return 0;
412
413  // Build the instantiated method declaration.
414  CXXRecordDecl *Record = cast<CXXRecordDecl>(Owner);
415  QualType ClassTy = SemaRef.Context.getTypeDeclType(Record);
416  DeclarationName Name
417    = SemaRef.Context.DeclarationNames.getCXXConstructorName(
418                                 SemaRef.Context.getCanonicalType(ClassTy));
419  CXXConstructorDecl *Constructor
420    = CXXConstructorDecl::Create(SemaRef.Context, Record, D->getLocation(),
421                                 Name, T, D->isExplicit(), D->isInline(),
422                                 false);
423  Constructor->setInstantiationOfMemberFunction(D);
424
425  // Attach the parameters
426  for (unsigned P = 0; P < Params.size(); ++P)
427    Params[P]->setOwningFunction(Constructor);
428  Constructor->setParams(SemaRef.Context, Params.data(), Params.size());
429
430  if (InitMethodInstantiation(Constructor, D))
431    Constructor->setInvalidDecl();
432
433  NamedDecl *PrevDecl
434    = SemaRef.LookupQualifiedName(Owner, Name, Sema::LookupOrdinaryName, true);
435
436  // In C++, the previous declaration we find might be a tag type
437  // (class or enum). In this case, the new declaration will hide the
438  // tag type. Note that this does does not apply if we're declaring a
439  // typedef (C++ [dcl.typedef]p4).
440  if (PrevDecl && PrevDecl->getIdentifierNamespace() == Decl::IDNS_Tag)
441    PrevDecl = 0;
442  bool Redeclaration = false;
443  bool OverloadableAttrRequired = false;
444  SemaRef.CheckFunctionDeclaration(Constructor, PrevDecl, Redeclaration,
445                                   /*FIXME:*/OverloadableAttrRequired);
446
447  Record->addedConstructor(SemaRef.Context, Constructor);
448  Owner->addDecl(Constructor);
449  return Constructor;
450}
451
452Decl *TemplateDeclInstantiator::VisitCXXDestructorDecl(CXXDestructorDecl *D) {
453  // FIXME: Look for existing, explicit specializations.
454  Sema::LocalInstantiationScope Scope(SemaRef);
455
456  llvm::SmallVector<ParmVarDecl *, 4> Params;
457  QualType T = InstantiateFunctionType(D, Params);
458  if (T.isNull())
459    return 0;
460  assert(Params.size() == 0 && "Destructor with parameters?");
461
462  // Build the instantiated destructor declaration.
463  CXXRecordDecl *Record = cast<CXXRecordDecl>(Owner);
464  QualType ClassTy =
465    SemaRef.Context.getCanonicalType(SemaRef.Context.getTypeDeclType(Record));
466  CXXDestructorDecl *Destructor
467    = CXXDestructorDecl::Create(SemaRef.Context, Record,
468                                D->getLocation(),
469             SemaRef.Context.DeclarationNames.getCXXDestructorName(ClassTy),
470                                T, D->isInline(), false);
471  Destructor->setInstantiationOfMemberFunction(D);
472  if (InitMethodInstantiation(Destructor, D))
473    Destructor->setInvalidDecl();
474
475  bool Redeclaration = false;
476  bool OverloadableAttrRequired = false;
477  NamedDecl *PrevDecl = 0;
478  SemaRef.CheckFunctionDeclaration(Destructor, PrevDecl, Redeclaration,
479                                   /*FIXME:*/OverloadableAttrRequired);
480  Owner->addDecl(Destructor);
481  return Destructor;
482}
483
484Decl *TemplateDeclInstantiator::VisitCXXConversionDecl(CXXConversionDecl *D) {
485  // FIXME: Look for existing, explicit specializations.
486  Sema::LocalInstantiationScope Scope(SemaRef);
487
488  llvm::SmallVector<ParmVarDecl *, 4> Params;
489  QualType T = InstantiateFunctionType(D, Params);
490  if (T.isNull())
491    return 0;
492  assert(Params.size() == 0 && "Destructor with parameters?");
493
494  // Build the instantiated conversion declaration.
495  CXXRecordDecl *Record = cast<CXXRecordDecl>(Owner);
496  QualType ClassTy = SemaRef.Context.getTypeDeclType(Record);
497  QualType ConvTy
498    = SemaRef.Context.getCanonicalType(T->getAsFunctionType()->getResultType());
499  CXXConversionDecl *Conversion
500    = CXXConversionDecl::Create(SemaRef.Context, Record,
501                                D->getLocation(),
502         SemaRef.Context.DeclarationNames.getCXXConversionFunctionName(ConvTy),
503                                T, D->isInline(), D->isExplicit());
504  Conversion->setInstantiationOfMemberFunction(D);
505  if (InitMethodInstantiation(Conversion, D))
506    Conversion->setInvalidDecl();
507
508  bool Redeclaration = false;
509  bool OverloadableAttrRequired = false;
510  NamedDecl *PrevDecl = 0;
511  SemaRef.CheckFunctionDeclaration(Conversion, PrevDecl, Redeclaration,
512                                   /*FIXME:*/OverloadableAttrRequired);
513  Owner->addDecl(Conversion);
514  return Conversion;
515}
516
517ParmVarDecl *TemplateDeclInstantiator::VisitParmVarDecl(ParmVarDecl *D) {
518  QualType OrigT = SemaRef.InstantiateType(D->getOriginalType(), TemplateArgs,
519                                           D->getLocation(), D->getDeclName());
520  if (OrigT.isNull())
521    return 0;
522
523  QualType T = SemaRef.adjustParameterType(OrigT);
524
525  if (D->getDefaultArg()) {
526    // FIXME: Leave a marker for "uninstantiated" default
527    // arguments. They only get instantiated on demand at the call
528    // site.
529    unsigned DiagID = SemaRef.Diags.getCustomDiagID(Diagnostic::Warning,
530        "sorry, dropping default argument during template instantiation");
531    SemaRef.Diag(D->getDefaultArg()->getSourceRange().getBegin(), DiagID)
532      << D->getDefaultArg()->getSourceRange();
533  }
534
535  // Allocate the parameter
536  ParmVarDecl *Param = 0;
537  if (T == OrigT)
538    Param = ParmVarDecl::Create(SemaRef.Context, Owner, D->getLocation(),
539                                D->getIdentifier(), T, D->getStorageClass(),
540                                0);
541  else
542    Param = OriginalParmVarDecl::Create(SemaRef.Context, Owner,
543                                        D->getLocation(), D->getIdentifier(),
544                                        T, OrigT, D->getStorageClass(), 0);
545
546  // Note: we don't try to instantiate function parameters until after
547  // we've instantiated the function's type. Therefore, we don't have
548  // to check for 'void' parameter types here.
549  SemaRef.CurrentInstantiationScope->InstantiatedLocal(D, Param);
550  return Param;
551}
552
553Decl *
554TemplateDeclInstantiator::VisitOriginalParmVarDecl(OriginalParmVarDecl *D) {
555  // Since parameter types can decay either before or after
556  // instantiation, we simply treat OriginalParmVarDecls as
557  // ParmVarDecls the same way, and create one or the other depending
558  // on what happens after template instantiation.
559  return VisitParmVarDecl(D);
560}
561
562Decl *Sema::InstantiateDecl(Decl *D, DeclContext *Owner,
563                            const TemplateArgumentList &TemplateArgs) {
564  TemplateDeclInstantiator Instantiator(*this, Owner, TemplateArgs);
565  return Instantiator.Visit(D);
566}
567
568/// \brief Instantiates the type of the given function, including
569/// instantiating all of the function parameters.
570///
571/// \param D The function that we will be instantiated
572///
573/// \param Params the instantiated parameter declarations
574
575/// \returns the instantiated function's type if successfull, a NULL
576/// type if there was an error.
577QualType
578TemplateDeclInstantiator::InstantiateFunctionType(FunctionDecl *D,
579                              llvm::SmallVectorImpl<ParmVarDecl *> &Params) {
580  bool InvalidDecl = false;
581
582  // Instantiate the function parameters
583  TemplateDeclInstantiator ParamInstantiator(SemaRef, 0, TemplateArgs);
584  llvm::SmallVector<QualType, 4> ParamTys;
585  for (FunctionDecl::param_iterator P = D->param_begin(),
586                                 PEnd = D->param_end();
587       P != PEnd; ++P) {
588    if (ParmVarDecl *PInst = ParamInstantiator.VisitParmVarDecl(*P)) {
589      if (PInst->getType()->isVoidType()) {
590        SemaRef.Diag(PInst->getLocation(), diag::err_param_with_void_type);
591        PInst->setInvalidDecl();
592      }
593      else if (SemaRef.RequireNonAbstractType(PInst->getLocation(),
594                                              PInst->getType(),
595                                              diag::err_abstract_type_in_decl,
596                                              Sema::AbstractParamType))
597        PInst->setInvalidDecl();
598
599      Params.push_back(PInst);
600      ParamTys.push_back(PInst->getType());
601
602      if (PInst->isInvalidDecl())
603        InvalidDecl = true;
604    } else
605      InvalidDecl = true;
606  }
607
608  // FIXME: Deallocate dead declarations.
609  if (InvalidDecl)
610    return QualType();
611
612  const FunctionProtoType *Proto = D->getType()->getAsFunctionProtoType();
613  assert(Proto && "Missing prototype?");
614  QualType ResultType
615    = SemaRef.InstantiateType(Proto->getResultType(), TemplateArgs,
616                              D->getLocation(), D->getDeclName());
617  if (ResultType.isNull())
618    return QualType();
619
620  return SemaRef.BuildFunctionType(ResultType, ParamTys.data(), ParamTys.size(),
621                                   Proto->isVariadic(), Proto->getTypeQuals(),
622                                   D->getLocation(), D->getDeclName());
623}
624
625/// \brief Initializes the common fields of an instantiation function
626/// declaration (New) from the corresponding fields of its template (Tmpl).
627///
628/// \returns true if there was an error
629bool
630TemplateDeclInstantiator::InitFunctionInstantiation(FunctionDecl *New,
631                                                    FunctionDecl *Tmpl) {
632  if (Tmpl->isDeleted())
633    New->setDeleted();
634
635  // If we are performing substituting explicitly-specified template arguments
636  // or deduced template arguments into a function template and we reach this
637  // point, we are now past the point where SFINAE applies and have committed
638  // to keeping the new function template specialization. We therefore
639  // convert the active template instantiation for the function template
640  // into a template instantiation for this specific function template
641  // specialization, which is not a SFINAE context, so that we diagnose any
642  // further errors in the declaration itself.
643  typedef Sema::ActiveTemplateInstantiation ActiveInstType;
644  ActiveInstType &ActiveInst = SemaRef.ActiveTemplateInstantiations.back();
645  if (ActiveInst.Kind == ActiveInstType::ExplicitTemplateArgumentSubstitution ||
646      ActiveInst.Kind == ActiveInstType::DeducedTemplateArgumentSubstitution) {
647    if (FunctionTemplateDecl *FunTmpl
648          = dyn_cast<FunctionTemplateDecl>((Decl *)ActiveInst.Entity)) {
649      assert(FunTmpl->getTemplatedDecl() == Tmpl &&
650             "Deduction from the wrong function template?");
651      (void) FunTmpl;
652      ActiveInst.Kind = ActiveInstType::TemplateInstantiation;
653      ActiveInst.Entity = reinterpret_cast<uintptr_t>(New);
654    }
655  }
656
657  return false;
658}
659
660/// \brief Initializes common fields of an instantiated method
661/// declaration (New) from the corresponding fields of its template
662/// (Tmpl).
663///
664/// \returns true if there was an error
665bool
666TemplateDeclInstantiator::InitMethodInstantiation(CXXMethodDecl *New,
667                                                  CXXMethodDecl *Tmpl) {
668  if (InitFunctionInstantiation(New, Tmpl))
669    return true;
670
671  CXXRecordDecl *Record = cast<CXXRecordDecl>(Owner);
672  New->setAccess(Tmpl->getAccess());
673  if (Tmpl->isVirtualAsWritten()) {
674    New->setVirtualAsWritten(true);
675    Record->setAggregate(false);
676    Record->setPOD(false);
677    Record->setPolymorphic(true);
678  }
679  if (Tmpl->isPure()) {
680    New->setPure();
681    Record->setAbstract(true);
682  }
683
684  // FIXME: attributes
685  // FIXME: New needs a pointer to Tmpl
686  return false;
687}
688
689/// \brief Instantiate the definition of the given function from its
690/// template.
691///
692/// \param PointOfInstantiation the point at which the instantiation was
693/// required. Note that this is not precisely a "point of instantiation"
694/// for the function, but it's close.
695///
696/// \param Function the already-instantiated declaration of a
697/// function template specialization or member function of a class template
698/// specialization.
699///
700/// \param Recursive if true, recursively instantiates any functions that
701/// are required by this instantiation.
702void Sema::InstantiateFunctionDefinition(SourceLocation PointOfInstantiation,
703                                         FunctionDecl *Function,
704                                         bool Recursive) {
705  if (Function->isInvalidDecl())
706    return;
707
708  assert(!Function->getBody() && "Already instantiated!");
709
710  // Find the function body that we'll be substituting.
711  const FunctionDecl *PatternDecl = 0;
712  if (FunctionTemplateDecl *Primary = Function->getPrimaryTemplate())
713    PatternDecl = Primary->getTemplatedDecl();
714  else
715    PatternDecl = Function->getInstantiatedFromMemberFunction();
716  Stmt *Pattern = 0;
717  if (PatternDecl)
718    Pattern = PatternDecl->getBody(PatternDecl);
719
720  if (!Pattern)
721    return;
722
723  InstantiatingTemplate Inst(*this, PointOfInstantiation, Function);
724  if (Inst)
725    return;
726
727  // If we're performing recursive template instantiation, create our own
728  // queue of pending implicit instantiations that we will instantiate later,
729  // while we're still within our own instantiation context.
730  std::deque<PendingImplicitInstantiation> SavedPendingImplicitInstantiations;
731  if (Recursive)
732    PendingImplicitInstantiations.swap(SavedPendingImplicitInstantiations);
733
734  ActOnStartOfFunctionDef(0, DeclPtrTy::make(Function));
735
736  // Introduce a new scope where local variable instantiations will be
737  // recorded.
738  LocalInstantiationScope Scope(*this);
739
740  // Introduce the instantiated function parameters into the local
741  // instantiation scope.
742  for (unsigned I = 0, N = PatternDecl->getNumParams(); I != N; ++I)
743    Scope.InstantiatedLocal(PatternDecl->getParamDecl(I),
744                            Function->getParamDecl(I));
745
746  // Enter the scope of this instantiation. We don't use
747  // PushDeclContext because we don't have a scope.
748  DeclContext *PreviousContext = CurContext;
749  CurContext = Function;
750
751  // Instantiate the function body.
752  OwningStmtResult Body
753    = InstantiateStmt(Pattern, getTemplateInstantiationArgs(Function));
754
755  ActOnFinishFunctionBody(DeclPtrTy::make(Function), move(Body),
756                          /*IsInstantiation=*/true);
757
758  CurContext = PreviousContext;
759
760  DeclGroupRef DG(Function);
761  Consumer.HandleTopLevelDecl(DG);
762
763  if (Recursive) {
764    // Instantiate any pending implicit instantiations found during the
765    // instantiation of this template.
766    PerformPendingImplicitInstantiations();
767
768    // Restore the set of pending implicit instantiations.
769    PendingImplicitInstantiations.swap(SavedPendingImplicitInstantiations);
770  }
771}
772
773/// \brief Instantiate the definition of the given variable from its
774/// template.
775///
776/// \param Var the already-instantiated declaration of a variable.
777void Sema::InstantiateVariableDefinition(VarDecl *Var) {
778  // FIXME: Implement this!
779}
780
781static bool isInstantiationOf(ASTContext &Ctx, NamedDecl *D, Decl *Other) {
782  if (D->getKind() != Other->getKind())
783    return false;
784
785  if (CXXRecordDecl *Record = dyn_cast<CXXRecordDecl>(Other))
786    return Record->getInstantiatedFromMemberClass()->getCanonicalDecl()
787             == D->getCanonicalDecl();
788
789  if (FunctionDecl *Function = dyn_cast<FunctionDecl>(Other))
790    return Function->getInstantiatedFromMemberFunction()->getCanonicalDecl()
791             == D->getCanonicalDecl();
792
793  if (EnumDecl *Enum = dyn_cast<EnumDecl>(Other))
794    return Enum->getInstantiatedFromMemberEnum()->getCanonicalDecl()
795             == D->getCanonicalDecl();
796
797  // FIXME: How can we find instantiations of anonymous unions?
798
799  return D->getDeclName() && isa<NamedDecl>(Other) &&
800    D->getDeclName() == cast<NamedDecl>(Other)->getDeclName();
801}
802
803template<typename ForwardIterator>
804static NamedDecl *findInstantiationOf(ASTContext &Ctx,
805                                      NamedDecl *D,
806                                      ForwardIterator first,
807                                      ForwardIterator last) {
808  for (; first != last; ++first)
809    if (isInstantiationOf(Ctx, D, *first))
810      return cast<NamedDecl>(*first);
811
812  return 0;
813}
814
815/// \brief Find the instantiation of the given declaration within the
816/// current instantiation.
817///
818/// This routine is intended to be used when \p D is a declaration
819/// referenced from within a template, that needs to mapped into the
820/// corresponding declaration within an instantiation. For example,
821/// given:
822///
823/// \code
824/// template<typename T>
825/// struct X {
826///   enum Kind {
827///     KnownValue = sizeof(T)
828///   };
829///
830///   bool getKind() const { return KnownValue; }
831/// };
832///
833/// template struct X<int>;
834/// \endcode
835///
836/// In the instantiation of X<int>::getKind(), we need to map the
837/// EnumConstantDecl for KnownValue (which refers to
838/// X<T>::<Kind>::KnownValue) to its instantiation
839/// (X<int>::<Kind>::KnownValue). InstantiateCurrentDeclRef() performs
840/// this mapping from within the instantiation of X<int>.
841NamedDecl * Sema::InstantiateCurrentDeclRef(NamedDecl *D) {
842  DeclContext *ParentDC = D->getDeclContext();
843  if (isa<ParmVarDecl>(D) || ParentDC->isFunctionOrMethod()) {
844    // D is a local of some kind. Look into the map of local
845    // declarations to their instantiations.
846    return cast<NamedDecl>(CurrentInstantiationScope->getInstantiationOf(D));
847  }
848
849  if (NamedDecl *ParentDecl = dyn_cast<NamedDecl>(ParentDC)) {
850    ParentDecl = InstantiateCurrentDeclRef(ParentDecl);
851    if (!ParentDecl)
852      return 0;
853
854    ParentDC = cast<DeclContext>(ParentDecl);
855  }
856
857  if (ParentDC != D->getDeclContext()) {
858    // We performed some kind of instantiation in the parent context,
859    // so now we need to look into the instantiated parent context to
860    // find the instantiation of the declaration D.
861    NamedDecl *Result = 0;
862    if (D->getDeclName()) {
863      DeclContext::lookup_result Found = ParentDC->lookup(D->getDeclName());
864      Result = findInstantiationOf(Context, D, Found.first, Found.second);
865    } else {
866      // Since we don't have a name for the entity we're looking for,
867      // our only option is to walk through all of the declarations to
868      // find that name. This will occur in a few cases:
869      //
870      //   - anonymous struct/union within a template
871      //   - unnamed class/struct/union/enum within a template
872      //
873      // FIXME: Find a better way to find these instantiations!
874      Result = findInstantiationOf(Context, D,
875                                   ParentDC->decls_begin(),
876                                   ParentDC->decls_end());
877    }
878    assert(Result && "Unable to find instantiation of declaration!");
879    D = Result;
880  }
881
882  if (CXXRecordDecl *Record = dyn_cast<CXXRecordDecl>(D))
883    if (ClassTemplateDecl *ClassTemplate
884          = Record->getDescribedClassTemplate()) {
885      // When the declaration D was parsed, it referred to the current
886      // instantiation. Therefore, look through the current context,
887      // which contains actual instantiations, to find the
888      // instantiation of the "current instantiation" that D refers
889      // to. Alternatively, we could just instantiate the
890      // injected-class-name with the current template arguments, but
891      // such an instantiation is far more expensive.
892      for (DeclContext *DC = CurContext; !DC->isFileContext();
893           DC = DC->getParent()) {
894        if (ClassTemplateSpecializationDecl *Spec
895              = dyn_cast<ClassTemplateSpecializationDecl>(DC))
896          if (Spec->getSpecializedTemplate()->getCanonicalDecl()
897              == ClassTemplate->getCanonicalDecl())
898            return Spec;
899      }
900
901      assert(false &&
902             "Unable to find declaration for the current instantiation");
903    }
904
905  return D;
906}
907
908/// \brief Performs template instantiation for all implicit template
909/// instantiations we have seen until this point.
910void Sema::PerformPendingImplicitInstantiations() {
911  while (!PendingImplicitInstantiations.empty()) {
912    PendingImplicitInstantiation Inst = PendingImplicitInstantiations.front();
913    PendingImplicitInstantiations.pop_front();
914
915    if (FunctionDecl *Function = dyn_cast<FunctionDecl>(Inst.first))
916      if (!Function->getBody())
917        InstantiateFunctionDefinition(/*FIXME:*/Inst.second, Function, true);
918
919    // FIXME: instantiate static member variables
920  }
921}
922