SemaTemplateInstantiateDecl.cpp revision 54dabfca850ca9e60e9ffb60003529f868d4d127 
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/ASTContext.h"
14#include "clang/AST/DeclTemplate.h"
15#include "clang/AST/DeclVisitor.h"
16#include "clang/AST/Expr.h"
17#include "llvm/Support/Compiler.h"
18
19using namespace clang;
20
21namespace {
22  class VISIBILITY_HIDDEN TemplateDeclInstantiator
23    : public DeclVisitor<TemplateDeclInstantiator, Decl *> {
24    Sema &SemaRef;
25    DeclContext *Owner;
26    const TemplateArgumentList &TemplateArgs;
27
28  public:
29    typedef Sema::OwningExprResult OwningExprResult;
30
31    TemplateDeclInstantiator(Sema &SemaRef, DeclContext *Owner,
32                             const TemplateArgumentList &TemplateArgs)
33      : SemaRef(SemaRef), Owner(Owner), TemplateArgs(TemplateArgs) { }
34
35    // FIXME: Once we get closer to completion, replace these
36    // manually-written declarations with automatically-generated ones
37    // from clang/AST/DeclNodes.def.
38    Decl *VisitTranslationUnitDecl(TranslationUnitDecl *D);
39    Decl *VisitNamespaceDecl(NamespaceDecl *D);
40    Decl *VisitTypedefDecl(TypedefDecl *D);
41    Decl *VisitVarDecl(VarDecl *D);
42    Decl *VisitFieldDecl(FieldDecl *D);
43    Decl *VisitStaticAssertDecl(StaticAssertDecl *D);
44    Decl *VisitEnumDecl(EnumDecl *D);
45    Decl *VisitEnumConstantDecl(EnumConstantDecl *D);
46    Decl *VisitCXXRecordDecl(CXXRecordDecl *D);
47    Decl *VisitCXXMethodDecl(CXXMethodDecl *D);
48    Decl *VisitCXXConstructorDecl(CXXConstructorDecl *D);
49    Decl *VisitCXXDestructorDecl(CXXDestructorDecl *D);
50    Decl *VisitCXXConversionDecl(CXXConversionDecl *D);
51    ParmVarDecl *VisitParmVarDecl(ParmVarDecl *D);
52    Decl *VisitOriginalParmVarDecl(OriginalParmVarDecl *D);
53
54    // Base case. FIXME: Remove once we can instantiate everything.
55    Decl *VisitDecl(Decl *) {
56      assert(false && "Template instantiation of unknown declaration kind!");
57      return 0;
58    }
59
60    // Helper functions for instantiating methods.
61    QualType InstantiateFunctionType(FunctionDecl *D,
62                             llvm::SmallVectorImpl<ParmVarDecl *> &Params);
63    bool InitMethodInstantiation(CXXMethodDecl *New, CXXMethodDecl *Tmpl);
64  };
65}
66
67Decl *
68TemplateDeclInstantiator::VisitTranslationUnitDecl(TranslationUnitDecl *D) {
69  assert(false && "Translation units cannot be instantiated");
70  return D;
71}
72
73Decl *
74TemplateDeclInstantiator::VisitNamespaceDecl(NamespaceDecl *D) {
75  assert(false && "Namespaces cannot be instantiated");
76  return D;
77}
78
79Decl *TemplateDeclInstantiator::VisitTypedefDecl(TypedefDecl *D) {
80  bool Invalid = false;
81  QualType T = D->getUnderlyingType();
82  if (T->isDependentType()) {
83    T = SemaRef.InstantiateType(T, TemplateArgs,
84                                D->getLocation(), D->getDeclName());
85    if (T.isNull()) {
86      Invalid = true;
87      T = SemaRef.Context.IntTy;
88    }
89  }
90
91  // Create the new typedef
92  TypedefDecl *Typedef
93    = TypedefDecl::Create(SemaRef.Context, Owner, D->getLocation(),
94                          D->getIdentifier(), T);
95  if (Invalid)
96    Typedef->setInvalidDecl();
97
98  Owner->addDecl(SemaRef.Context, Typedef);
99  return Typedef;
100}
101
102Decl *TemplateDeclInstantiator::VisitVarDecl(VarDecl *D) {
103  // Instantiate the type of the declaration
104  QualType T = SemaRef.InstantiateType(D->getType(), TemplateArgs,
105                                       D->getTypeSpecStartLoc(),
106                                       D->getDeclName());
107  if (T.isNull())
108    return 0;
109
110  // Build the instantiataed declaration
111  VarDecl *Var = VarDecl::Create(SemaRef.Context, Owner,
112                                 D->getLocation(), D->getIdentifier(),
113                                 T, D->getStorageClass(),
114                                 D->getTypeSpecStartLoc());
115  Var->setThreadSpecified(D->isThreadSpecified());
116  Var->setCXXDirectInitializer(D->hasCXXDirectInitializer());
117  Var->setDeclaredInCondition(D->isDeclaredInCondition());
118
119  // FIXME: In theory, we could have a previous declaration for
120  // variables that are not static data members.
121  bool Redeclaration = false;
122  SemaRef.CheckVariableDeclaration(Var, 0, Redeclaration);
123  Owner->addDecl(SemaRef.Context, Var);
124
125  if (D->getInit()) {
126    OwningExprResult Init
127      = SemaRef.InstantiateExpr(D->getInit(), TemplateArgs);
128    if (Init.isInvalid())
129      Var->setInvalidDecl();
130    else
131      SemaRef.AddInitializerToDecl(Sema::DeclPtrTy::make(Var), move(Init),
132                                   D->hasCXXDirectInitializer());
133  }
134
135  return Var;
136}
137
138Decl *TemplateDeclInstantiator::VisitFieldDecl(FieldDecl *D) {
139  bool Invalid = false;
140  QualType T = D->getType();
141  if (T->isDependentType())  {
142    T = SemaRef.InstantiateType(T, TemplateArgs,
143                                D->getLocation(), D->getDeclName());
144    if (!T.isNull() && T->isFunctionType()) {
145      // C++ [temp.arg.type]p3:
146      //   If a declaration acquires a function type through a type
147      //   dependent on a template-parameter and this causes a
148      //   declaration that does not use the syntactic form of a
149      //   function declarator to have function type, the program is
150      //   ill-formed.
151      SemaRef.Diag(D->getLocation(), diag::err_field_instantiates_to_function)
152        << T;
153      T = QualType();
154      Invalid = true;
155    }
156  }
157
158  Expr *BitWidth = D->getBitWidth();
159  if (Invalid)
160    BitWidth = 0;
161  else if (BitWidth) {
162    OwningExprResult InstantiatedBitWidth
163      = SemaRef.InstantiateExpr(BitWidth, TemplateArgs);
164    if (InstantiatedBitWidth.isInvalid()) {
165      Invalid = true;
166      BitWidth = 0;
167    } else
168      BitWidth = InstantiatedBitWidth.takeAs<Expr>();
169  }
170
171  FieldDecl *Field = SemaRef.CheckFieldDecl(D->getDeclName(), T,
172                                            cast<RecordDecl>(Owner),
173                                            D->getLocation(),
174                                            D->isMutable(),
175                                            BitWidth,
176                                            D->getAccess(),
177                                            0);
178  if (Field) {
179    if (Invalid)
180      Field->setInvalidDecl();
181
182    Owner->addDecl(SemaRef.Context, Field);
183  }
184
185  return Field;
186}
187
188Decl *TemplateDeclInstantiator::VisitStaticAssertDecl(StaticAssertDecl *D) {
189  Expr *AssertExpr = D->getAssertExpr();
190
191  OwningExprResult InstantiatedAssertExpr
192    = SemaRef.InstantiateExpr(AssertExpr, TemplateArgs);
193  if (InstantiatedAssertExpr.isInvalid())
194    return 0;
195
196  OwningExprResult Message = SemaRef.Clone(D->getMessage());
197  Decl *StaticAssert
198    = SemaRef.ActOnStaticAssertDeclaration(D->getLocation(),
199                                           move(InstantiatedAssertExpr),
200                                           move(Message)).getAs<Decl>();
201  return StaticAssert;
202}
203
204Decl *TemplateDeclInstantiator::VisitEnumDecl(EnumDecl *D) {
205  EnumDecl *Enum = EnumDecl::Create(SemaRef.Context, Owner,
206                                    D->getLocation(), D->getIdentifier(),
207                                    /*PrevDecl=*/0);
208  Enum->setAccess(D->getAccess());
209  Owner->addDecl(SemaRef.Context, Enum);
210  Enum->startDefinition();
211
212  llvm::SmallVector<Sema::DeclPtrTy, 16> Enumerators;
213
214  EnumConstantDecl *LastEnumConst = 0;
215  for (EnumDecl::enumerator_iterator EC = D->enumerator_begin(SemaRef.Context),
216         ECEnd = D->enumerator_end(SemaRef.Context);
217       EC != ECEnd; ++EC) {
218    // The specified value for the enumerator.
219    OwningExprResult Value = SemaRef.Owned((Expr *)0);
220    if (Expr *UninstValue = EC->getInitExpr())
221      Value = SemaRef.InstantiateExpr(UninstValue, TemplateArgs);
222
223    // Drop the initial value and continue.
224    bool isInvalid = false;
225    if (Value.isInvalid()) {
226      Value = SemaRef.Owned((Expr *)0);
227      isInvalid = true;
228    }
229
230    EnumConstantDecl *EnumConst
231      = SemaRef.CheckEnumConstant(Enum, LastEnumConst,
232                                  EC->getLocation(), EC->getIdentifier(),
233                                  move(Value));
234
235    if (isInvalid) {
236      if (EnumConst)
237        EnumConst->setInvalidDecl();
238      Enum->setInvalidDecl();
239    }
240
241    if (EnumConst) {
242      Enum->addDecl(SemaRef.Context, EnumConst);
243      Enumerators.push_back(Sema::DeclPtrTy::make(EnumConst));
244      LastEnumConst = EnumConst;
245    }
246  }
247
248  SemaRef.ActOnEnumBody(Enum->getLocation(), Sema::DeclPtrTy::make(Enum),
249                        &Enumerators[0], Enumerators.size());
250
251  return Enum;
252}
253
254Decl *TemplateDeclInstantiator::VisitEnumConstantDecl(EnumConstantDecl *D) {
255  assert(false && "EnumConstantDecls can only occur within EnumDecls.");
256  return 0;
257}
258
259Decl *TemplateDeclInstantiator::VisitCXXRecordDecl(CXXRecordDecl *D) {
260  CXXRecordDecl *PrevDecl = 0;
261  if (D->isInjectedClassName())
262    PrevDecl = cast<CXXRecordDecl>(Owner);
263
264  CXXRecordDecl *Record
265    = CXXRecordDecl::Create(SemaRef.Context, D->getTagKind(), Owner,
266                            D->getLocation(), D->getIdentifier(), PrevDecl);
267  Record->setImplicit(D->isImplicit());
268  Record->setAccess(D->getAccess());
269  if (!D->isInjectedClassName())
270    Record->setInstantiationOfMemberClass(D);
271
272  Owner->addDecl(SemaRef.Context, Record);
273  return Record;
274}
275
276Decl *TemplateDeclInstantiator::VisitCXXMethodDecl(CXXMethodDecl *D) {
277  // Only handle actual methods; we'll deal with constructors,
278  // destructors, etc. separately.
279  if (D->getKind() != Decl::CXXMethod)
280    return 0;
281
282  Sema::LocalInstantiationScope Scope(SemaRef);
283
284  llvm::SmallVector<ParmVarDecl *, 16> Params;
285  QualType T = InstantiateFunctionType(D, Params);
286  if (T.isNull())
287    return 0;
288
289  // Build the instantiated method declaration.
290  CXXRecordDecl *Record = cast<CXXRecordDecl>(Owner);
291  CXXMethodDecl *Method
292    = CXXMethodDecl::Create(SemaRef.Context, Record, D->getLocation(),
293                            D->getDeclName(), T, D->isStatic(),
294                            D->isInline());
295  Method->setInstantiationOfMemberFunction(D);
296
297  // Attach the parameters
298  for (unsigned P = 0; P < Params.size(); ++P)
299    Params[P]->setOwningFunction(Method);
300  Method->setParams(SemaRef.Context, &Params[0], Params.size());
301
302  if (InitMethodInstantiation(Method, D))
303    Method->setInvalidDecl();
304
305  NamedDecl *PrevDecl
306    = SemaRef.LookupQualifiedName(Owner, Method->getDeclName(),
307                                  Sema::LookupOrdinaryName, true);
308  // In C++, the previous declaration we find might be a tag type
309  // (class or enum). In this case, the new declaration will hide the
310  // tag type. Note that this does does not apply if we're declaring a
311  // typedef (C++ [dcl.typedef]p4).
312  if (PrevDecl && PrevDecl->getIdentifierNamespace() == Decl::IDNS_Tag)
313    PrevDecl = 0;
314  bool Redeclaration = false;
315  bool OverloadableAttrRequired = false;
316  SemaRef.CheckFunctionDeclaration(Method, PrevDecl, Redeclaration,
317                                   /*FIXME:*/OverloadableAttrRequired);
318
319  if (!Method->isInvalidDecl() || !PrevDecl)
320    Owner->addDecl(SemaRef.Context, Method);
321  return Method;
322}
323
324Decl *TemplateDeclInstantiator::VisitCXXConstructorDecl(CXXConstructorDecl *D) {
325  Sema::LocalInstantiationScope Scope(SemaRef);
326
327  llvm::SmallVector<ParmVarDecl *, 16> Params;
328  QualType T = InstantiateFunctionType(D, Params);
329  if (T.isNull())
330    return 0;
331
332  // Build the instantiated method declaration.
333  CXXRecordDecl *Record = cast<CXXRecordDecl>(Owner);
334  QualType ClassTy = SemaRef.Context.getTypeDeclType(Record);
335  DeclarationName Name
336    = SemaRef.Context.DeclarationNames.getCXXConstructorName(ClassTy);
337  CXXConstructorDecl *Constructor
338    = CXXConstructorDecl::Create(SemaRef.Context, Record, D->getLocation(),
339                                 Name, T, D->isExplicit(), D->isInline(),
340                                 false);
341  Constructor->setInstantiationOfMemberFunction(D);
342
343  // Attach the parameters
344  for (unsigned P = 0; P < Params.size(); ++P)
345    Params[P]->setOwningFunction(Constructor);
346  Constructor->setParams(SemaRef.Context, &Params[0], Params.size());
347
348  if (InitMethodInstantiation(Constructor, D))
349    Constructor->setInvalidDecl();
350
351  NamedDecl *PrevDecl
352    = SemaRef.LookupQualifiedName(Owner, Name, Sema::LookupOrdinaryName, true);
353
354  // In C++, the previous declaration we find might be a tag type
355  // (class or enum). In this case, the new declaration will hide the
356  // tag type. Note that this does does not apply if we're declaring a
357  // typedef (C++ [dcl.typedef]p4).
358  if (PrevDecl && PrevDecl->getIdentifierNamespace() == Decl::IDNS_Tag)
359    PrevDecl = 0;
360  bool Redeclaration = false;
361  bool OverloadableAttrRequired = false;
362  SemaRef.CheckFunctionDeclaration(Constructor, PrevDecl, Redeclaration,
363                                   /*FIXME:*/OverloadableAttrRequired);
364
365  Owner->addDecl(SemaRef.Context, Constructor);
366  return Constructor;
367}
368
369Decl *TemplateDeclInstantiator::VisitCXXDestructorDecl(CXXDestructorDecl *D) {
370  Sema::LocalInstantiationScope Scope(SemaRef);
371
372  llvm::SmallVector<ParmVarDecl *, 16> Params;
373  QualType T = InstantiateFunctionType(D, Params);
374  if (T.isNull())
375    return 0;
376  assert(Params.size() == 0 && "Destructor with parameters?");
377
378  // Build the instantiated destructor declaration.
379  CXXRecordDecl *Record = cast<CXXRecordDecl>(Owner);
380  QualType ClassTy = SemaRef.Context.getTypeDeclType(Record);
381  CXXDestructorDecl *Destructor
382    = CXXDestructorDecl::Create(SemaRef.Context, Record,
383                                D->getLocation(),
384             SemaRef.Context.DeclarationNames.getCXXDestructorName(ClassTy),
385                                T, D->isInline(), false);
386  Destructor->setInstantiationOfMemberFunction(D);
387  if (InitMethodInstantiation(Destructor, D))
388    Destructor->setInvalidDecl();
389
390  bool Redeclaration = false;
391  bool OverloadableAttrRequired = false;
392  NamedDecl *PrevDecl = 0;
393  SemaRef.CheckFunctionDeclaration(Destructor, PrevDecl, Redeclaration,
394                                   /*FIXME:*/OverloadableAttrRequired);
395  Owner->addDecl(SemaRef.Context, Destructor);
396  return Destructor;
397}
398
399Decl *TemplateDeclInstantiator::VisitCXXConversionDecl(CXXConversionDecl *D) {
400  Sema::LocalInstantiationScope Scope(SemaRef);
401
402  llvm::SmallVector<ParmVarDecl *, 16> Params;
403  QualType T = InstantiateFunctionType(D, Params);
404  if (T.isNull())
405    return 0;
406  assert(Params.size() == 0 && "Destructor with parameters?");
407
408  // Build the instantiated conversion declaration.
409  CXXRecordDecl *Record = cast<CXXRecordDecl>(Owner);
410  QualType ClassTy = SemaRef.Context.getTypeDeclType(Record);
411  QualType ConvTy
412    = SemaRef.Context.getCanonicalType(T->getAsFunctionType()->getResultType());
413  CXXConversionDecl *Conversion
414    = CXXConversionDecl::Create(SemaRef.Context, Record,
415                                D->getLocation(),
416         SemaRef.Context.DeclarationNames.getCXXConversionFunctionName(ConvTy),
417                                T, D->isInline(), D->isExplicit());
418  Conversion->setInstantiationOfMemberFunction(D);
419  if (InitMethodInstantiation(Conversion, D))
420    Conversion->setInvalidDecl();
421
422  bool Redeclaration = false;
423  bool OverloadableAttrRequired = false;
424  NamedDecl *PrevDecl = 0;
425  SemaRef.CheckFunctionDeclaration(Conversion, PrevDecl, Redeclaration,
426                                   /*FIXME:*/OverloadableAttrRequired);
427  Owner->addDecl(SemaRef.Context, Conversion);
428  return Conversion;
429}
430
431ParmVarDecl *TemplateDeclInstantiator::VisitParmVarDecl(ParmVarDecl *D) {
432  QualType OrigT = SemaRef.InstantiateType(D->getOriginalType(), TemplateArgs,
433                                           D->getLocation(), D->getDeclName());
434  if (OrigT.isNull())
435    return 0;
436
437  QualType T = SemaRef.adjustParameterType(OrigT);
438
439  if (D->getDefaultArg()) {
440    // FIXME: Leave a marker for "uninstantiated" default
441    // arguments. They only get instantiated on demand at the call
442    // site.
443    unsigned DiagID = SemaRef.Diags.getCustomDiagID(Diagnostic::Warning,
444        "sorry, dropping default argument during template instantiation");
445    SemaRef.Diag(D->getDefaultArg()->getSourceRange().getBegin(), DiagID)
446      << D->getDefaultArg()->getSourceRange();
447  }
448
449  // Allocate the parameter
450  ParmVarDecl *Param = 0;
451  if (T == OrigT)
452    Param = ParmVarDecl::Create(SemaRef.Context, Owner, D->getLocation(),
453                                D->getIdentifier(), T, D->getStorageClass(),
454                                0);
455  else
456    Param = OriginalParmVarDecl::Create(SemaRef.Context, Owner,
457                                        D->getLocation(), D->getIdentifier(),
458                                        T, OrigT, D->getStorageClass(), 0);
459
460  // Note: we don't try to instantiate function parameters until after
461  // we've instantiated the function's type. Therefore, we don't have
462  // to check for 'void' parameter types here.
463  SemaRef.CurrentInstantiationScope->InstantiatedLocal(D, Param);
464  return Param;
465}
466
467Decl *
468TemplateDeclInstantiator::VisitOriginalParmVarDecl(OriginalParmVarDecl *D) {
469  // Since parameter types can decay either before or after
470  // instantiation, we simply treat OriginalParmVarDecls as
471  // ParmVarDecls the same way, and create one or the other depending
472  // on what happens after template instantiation.
473  return VisitParmVarDecl(D);
474}
475
476Decl *Sema::InstantiateDecl(Decl *D, DeclContext *Owner,
477                            const TemplateArgumentList &TemplateArgs) {
478  TemplateDeclInstantiator Instantiator(*this, Owner, TemplateArgs);
479  return Instantiator.Visit(D);
480}
481
482/// \brief Instantiates the type of the given function, including
483/// instantiating all of the function parameters.
484///
485/// \param D The function that we will be instantiated
486///
487/// \param Params the instantiated parameter declarations
488
489/// \returns the instantiated function's type if successfull, a NULL
490/// type if there was an error.
491QualType
492TemplateDeclInstantiator::InstantiateFunctionType(FunctionDecl *D,
493                              llvm::SmallVectorImpl<ParmVarDecl *> &Params) {
494  bool InvalidDecl = false;
495
496  // Instantiate the function parameters
497  TemplateDeclInstantiator ParamInstantiator(SemaRef, 0, TemplateArgs);
498  llvm::SmallVector<QualType, 16> ParamTys;
499  for (FunctionDecl::param_iterator P = D->param_begin(),
500                                 PEnd = D->param_end();
501       P != PEnd; ++P) {
502    if (ParmVarDecl *PInst = ParamInstantiator.VisitParmVarDecl(*P)) {
503      if (PInst->getType()->isVoidType()) {
504        SemaRef.Diag(PInst->getLocation(), diag::err_param_with_void_type);
505        PInst->setInvalidDecl();
506      }
507      else if (SemaRef.RequireNonAbstractType(PInst->getLocation(),
508                                              PInst->getType(),
509                                              diag::err_abstract_type_in_decl,
510                                              Sema::AbstractParamType))
511        PInst->setInvalidDecl();
512
513      Params.push_back(PInst);
514      ParamTys.push_back(PInst->getType());
515
516      if (PInst->isInvalidDecl())
517        InvalidDecl = true;
518    } else
519      InvalidDecl = true;
520  }
521
522  // FIXME: Deallocate dead declarations.
523  if (InvalidDecl)
524    return QualType();
525
526  const FunctionProtoType *Proto = D->getType()->getAsFunctionProtoType();
527  assert(Proto && "Missing prototype?");
528  QualType ResultType
529    = SemaRef.InstantiateType(Proto->getResultType(), TemplateArgs,
530                              D->getLocation(), D->getDeclName());
531  if (ResultType.isNull())
532    return QualType();
533
534  return SemaRef.BuildFunctionType(ResultType, &ParamTys[0], ParamTys.size(),
535                                   Proto->isVariadic(), Proto->getTypeQuals(),
536                                   D->getLocation(), D->getDeclName());
537}
538
539/// \brief Initializes common fields of an instantiated method
540/// declaration (New) from the corresponding fields of its template
541/// (Tmpl).
542///
543/// \returns true if there was an error
544bool
545TemplateDeclInstantiator::InitMethodInstantiation(CXXMethodDecl *New,
546                                                  CXXMethodDecl *Tmpl) {
547  CXXRecordDecl *Record = cast<CXXRecordDecl>(Owner);
548  New->setAccess(Tmpl->getAccess());
549  if (Tmpl->isVirtualAsWritten()) {
550    New->setVirtualAsWritten(true);
551    Record->setAggregate(false);
552    Record->setPOD(false);
553    Record->setPolymorphic(true);
554  }
555  if (Tmpl->isDeleted())
556    New->setDeleted();
557  if (Tmpl->isPure()) {
558    New->setPure();
559    Record->setAbstract(true);
560  }
561
562  // FIXME: attributes
563  // FIXME: New needs a pointer to Tmpl
564  return false;
565}
566
567/// \brief Instantiate the definition of the given function from its
568/// template.
569///
570/// \param Function the already-instantiated declaration of a
571/// function.
572void Sema::InstantiateFunctionDefinition(FunctionDecl *Function) {
573  // FIXME: make this work for function template specializations, too.
574
575  if (Function->isInvalidDecl())
576    return;
577
578  // Find the function body that we'll be substituting.
579  const FunctionDecl *PatternDecl
580    = Function->getInstantiatedFromMemberFunction();
581  Stmt *Pattern = 0;
582  if (PatternDecl)
583    Pattern = PatternDecl->getBody(Context, PatternDecl);
584
585  if (!Pattern)
586    return;
587
588  // Introduce a new scope where local variable instantiations will be
589  // recorded.
590  LocalInstantiationScope Scope(*this);
591
592  // Introduce the instantiated function parameters into the local
593  // instantiation scope.
594  for (unsigned I = 0, N = PatternDecl->getNumParams(); I != N; ++I)
595    Scope.InstantiatedLocal(PatternDecl->getParamDecl(I),
596                            Function->getParamDecl(I));
597
598  // Instantiate the function body.
599  OwningStmtResult Body
600    = InstantiateStmt(Pattern, getTemplateInstantiationArgs(Function));
601  if (Body.isInvalid())
602    Function->setInvalidDecl(true);
603  else
604    Function->setBody(Body.takeAs<Stmt>());
605}
606
607/// \brief Instantiate the definition of the given variable from its
608/// template.
609///
610/// \param Var the already-instantiated declaration of a variable.
611void Sema::InstantiateVariableDefinition(VarDecl *Var) {
612  // FIXME: Implement this!
613}
614