SemaTemplateInstantiate.cpp revision 538fccb44c521f5f26e7aa4cebf6a55284e28b3d 
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 "clang/Sema/SemaInternal.h"
14#include "TreeTransform.h"
15#include "clang/AST/ASTConsumer.h"
16#include "clang/AST/ASTContext.h"
17#include "clang/AST/DeclTemplate.h"
18#include "clang/AST/Expr.h"
19#include "clang/Basic/LangOptions.h"
20#include "clang/Sema/DeclSpec.h"
21#include "clang/Sema/Initialization.h"
22#include "clang/Sema/Lookup.h"
23#include "clang/Sema/Template.h"
24#include "clang/Sema/TemplateDeduction.h"
25
26using namespace clang;
27using namespace sema;
28
29//===----------------------------------------------------------------------===/
30// Template Instantiation Support
31//===----------------------------------------------------------------------===/
32
33/// \brief Retrieve the template argument list(s) that should be used to
34/// instantiate the definition of the given declaration.
35///
36/// \param D the declaration for which we are computing template instantiation
37/// arguments.
38///
39/// \param Innermost if non-NULL, the innermost template argument list.
40///
41/// \param RelativeToPrimary true if we should get the template
42/// arguments relative to the primary template, even when we're
43/// dealing with a specialization. This is only relevant for function
44/// template specializations.
45///
46/// \param Pattern If non-NULL, indicates the pattern from which we will be
47/// instantiating the definition of the given declaration, \p D. This is
48/// used to determine the proper set of template instantiation arguments for
49/// friend function template specializations.
50MultiLevelTemplateArgumentList
51Sema::getTemplateInstantiationArgs(NamedDecl *D,
52                                   const TemplateArgumentList *Innermost,
53                                   bool RelativeToPrimary,
54                                   const FunctionDecl *Pattern) {
55  // Accumulate the set of template argument lists in this structure.
56  MultiLevelTemplateArgumentList Result;
57
58  if (Innermost)
59    Result.addOuterTemplateArguments(Innermost);
60
61  DeclContext *Ctx = dyn_cast<DeclContext>(D);
62  if (!Ctx) {
63    Ctx = D->getDeclContext();
64
65    // If we have a template template parameter with translation unit context,
66    // then we're performing substitution into a default template argument of
67    // this template template parameter before we've constructed the template
68    // that will own this template template parameter. In this case, we
69    // use empty template parameter lists for all of the outer templates
70    // to avoid performing any substitutions.
71    if (Ctx->isTranslationUnit()) {
72      if (TemplateTemplateParmDecl *TTP
73                                      = dyn_cast<TemplateTemplateParmDecl>(D)) {
74        for (unsigned I = 0, N = TTP->getDepth() + 1; I != N; ++I)
75          Result.addOuterTemplateArguments(None);
76        return Result;
77      }
78    }
79  }
80
81  while (!Ctx->isFileContext()) {
82    // Add template arguments from a class template instantiation.
83    if (ClassTemplateSpecializationDecl *Spec
84          = dyn_cast<ClassTemplateSpecializationDecl>(Ctx)) {
85      // We're done when we hit an explicit specialization.
86      if (Spec->getSpecializationKind() == TSK_ExplicitSpecialization &&
87          !isa<ClassTemplatePartialSpecializationDecl>(Spec))
88        break;
89
90      Result.addOuterTemplateArguments(&Spec->getTemplateInstantiationArgs());
91
92      // If this class template specialization was instantiated from a
93      // specialized member that is a class template, we're done.
94      assert(Spec->getSpecializedTemplate() && "No class template?");
95      if (Spec->getSpecializedTemplate()->isMemberSpecialization())
96        break;
97    }
98    // Add template arguments from a function template specialization.
99    else if (FunctionDecl *Function = dyn_cast<FunctionDecl>(Ctx)) {
100      if (!RelativeToPrimary &&
101          (Function->getTemplateSpecializationKind() ==
102                                                  TSK_ExplicitSpecialization &&
103           !Function->getClassScopeSpecializationPattern()))
104        break;
105
106      if (const TemplateArgumentList *TemplateArgs
107            = Function->getTemplateSpecializationArgs()) {
108        // Add the template arguments for this specialization.
109        Result.addOuterTemplateArguments(TemplateArgs);
110
111        // If this function was instantiated from a specialized member that is
112        // a function template, we're done.
113        assert(Function->getPrimaryTemplate() && "No function template?");
114        if (Function->getPrimaryTemplate()->isMemberSpecialization())
115          break;
116      } else if (FunctionTemplateDecl *FunTmpl
117                                   = Function->getDescribedFunctionTemplate()) {
118        // Add the "injected" template arguments.
119        Result.addOuterTemplateArguments(FunTmpl->getInjectedTemplateArgs());
120      }
121
122      // If this is a friend declaration and it declares an entity at
123      // namespace scope, take arguments from its lexical parent
124      // instead of its semantic parent, unless of course the pattern we're
125      // instantiating actually comes from the file's context!
126      if (Function->getFriendObjectKind() &&
127          Function->getDeclContext()->isFileContext() &&
128          (!Pattern || !Pattern->getLexicalDeclContext()->isFileContext())) {
129        Ctx = Function->getLexicalDeclContext();
130        RelativeToPrimary = false;
131        continue;
132      }
133    } else if (CXXRecordDecl *Rec = dyn_cast<CXXRecordDecl>(Ctx)) {
134      if (ClassTemplateDecl *ClassTemplate = Rec->getDescribedClassTemplate()) {
135        QualType T = ClassTemplate->getInjectedClassNameSpecialization();
136        const TemplateSpecializationType *TST =
137            cast<TemplateSpecializationType>(Context.getCanonicalType(T));
138        Result.addOuterTemplateArguments(
139            llvm::makeArrayRef(TST->getArgs(), TST->getNumArgs()));
140        if (ClassTemplate->isMemberSpecialization())
141          break;
142      }
143    }
144
145    Ctx = Ctx->getParent();
146    RelativeToPrimary = false;
147  }
148
149  return Result;
150}
151
152bool Sema::ActiveTemplateInstantiation::isInstantiationRecord() const {
153  switch (Kind) {
154  case TemplateInstantiation:
155  case ExceptionSpecInstantiation:
156  case DefaultTemplateArgumentInstantiation:
157  case DefaultFunctionArgumentInstantiation:
158  case ExplicitTemplateArgumentSubstitution:
159  case DeducedTemplateArgumentSubstitution:
160  case PriorTemplateArgumentSubstitution:
161    return true;
162
163  case DefaultTemplateArgumentChecking:
164    return false;
165  }
166
167  llvm_unreachable("Invalid InstantiationKind!");
168}
169
170Sema::InstantiatingTemplate::
171InstantiatingTemplate(Sema &SemaRef, SourceLocation PointOfInstantiation,
172                      Decl *Entity,
173                      SourceRange InstantiationRange)
174  : SemaRef(SemaRef),
175    SavedInNonInstantiationSFINAEContext(
176                                        SemaRef.InNonInstantiationSFINAEContext)
177{
178  Invalid = CheckInstantiationDepth(PointOfInstantiation,
179                                    InstantiationRange);
180  if (!Invalid) {
181    ActiveTemplateInstantiation Inst;
182    Inst.Kind = ActiveTemplateInstantiation::TemplateInstantiation;
183    Inst.PointOfInstantiation = PointOfInstantiation;
184    Inst.Entity = Entity;
185    Inst.TemplateArgs = 0;
186    Inst.NumTemplateArgs = 0;
187    Inst.InstantiationRange = InstantiationRange;
188    SemaRef.InNonInstantiationSFINAEContext = false;
189    SemaRef.ActiveTemplateInstantiations.push_back(Inst);
190  }
191}
192
193Sema::InstantiatingTemplate::
194InstantiatingTemplate(Sema &SemaRef, SourceLocation PointOfInstantiation,
195                      FunctionDecl *Entity, ExceptionSpecification,
196                      SourceRange InstantiationRange)
197  : SemaRef(SemaRef),
198    SavedInNonInstantiationSFINAEContext(
199                                        SemaRef.InNonInstantiationSFINAEContext)
200{
201  Invalid = CheckInstantiationDepth(PointOfInstantiation,
202                                    InstantiationRange);
203  if (!Invalid) {
204    ActiveTemplateInstantiation Inst;
205    Inst.Kind = ActiveTemplateInstantiation::ExceptionSpecInstantiation;
206    Inst.PointOfInstantiation = PointOfInstantiation;
207    Inst.Entity = Entity;
208    Inst.TemplateArgs = 0;
209    Inst.NumTemplateArgs = 0;
210    Inst.InstantiationRange = InstantiationRange;
211    SemaRef.InNonInstantiationSFINAEContext = false;
212    SemaRef.ActiveTemplateInstantiations.push_back(Inst);
213  }
214}
215
216Sema::InstantiatingTemplate::
217InstantiatingTemplate(Sema &SemaRef, SourceLocation PointOfInstantiation,
218                      TemplateDecl *Template,
219                      ArrayRef<TemplateArgument> TemplateArgs,
220                      SourceRange InstantiationRange)
221  : SemaRef(SemaRef),
222    SavedInNonInstantiationSFINAEContext(
223                                     SemaRef.InNonInstantiationSFINAEContext)
224{
225  Invalid = CheckInstantiationDepth(PointOfInstantiation,
226                                    InstantiationRange);
227  if (!Invalid) {
228    ActiveTemplateInstantiation Inst;
229    Inst.Kind
230      = ActiveTemplateInstantiation::DefaultTemplateArgumentInstantiation;
231    Inst.PointOfInstantiation = PointOfInstantiation;
232    Inst.Entity = Template;
233    Inst.TemplateArgs = TemplateArgs.data();
234    Inst.NumTemplateArgs = TemplateArgs.size();
235    Inst.InstantiationRange = InstantiationRange;
236    SemaRef.InNonInstantiationSFINAEContext = false;
237    SemaRef.ActiveTemplateInstantiations.push_back(Inst);
238  }
239}
240
241Sema::InstantiatingTemplate::
242InstantiatingTemplate(Sema &SemaRef, SourceLocation PointOfInstantiation,
243                      FunctionTemplateDecl *FunctionTemplate,
244                      ArrayRef<TemplateArgument> TemplateArgs,
245                      ActiveTemplateInstantiation::InstantiationKind Kind,
246                      sema::TemplateDeductionInfo &DeductionInfo,
247                      SourceRange InstantiationRange)
248  : SemaRef(SemaRef),
249    SavedInNonInstantiationSFINAEContext(
250                                     SemaRef.InNonInstantiationSFINAEContext)
251{
252  Invalid = CheckInstantiationDepth(PointOfInstantiation, InstantiationRange);
253  if (!Invalid) {
254    ActiveTemplateInstantiation Inst;
255    Inst.Kind = Kind;
256    Inst.PointOfInstantiation = PointOfInstantiation;
257    Inst.Entity = FunctionTemplate;
258    Inst.TemplateArgs = TemplateArgs.data();
259    Inst.NumTemplateArgs = TemplateArgs.size();
260    Inst.DeductionInfo = &DeductionInfo;
261    Inst.InstantiationRange = InstantiationRange;
262    SemaRef.InNonInstantiationSFINAEContext = false;
263    SemaRef.ActiveTemplateInstantiations.push_back(Inst);
264
265    if (!Inst.isInstantiationRecord())
266      ++SemaRef.NonInstantiationEntries;
267  }
268}
269
270Sema::InstantiatingTemplate::
271InstantiatingTemplate(Sema &SemaRef, SourceLocation PointOfInstantiation,
272                      ClassTemplatePartialSpecializationDecl *PartialSpec,
273                      ArrayRef<TemplateArgument> TemplateArgs,
274                      sema::TemplateDeductionInfo &DeductionInfo,
275                      SourceRange InstantiationRange)
276  : SemaRef(SemaRef),
277    SavedInNonInstantiationSFINAEContext(
278                                     SemaRef.InNonInstantiationSFINAEContext)
279{
280  Invalid = CheckInstantiationDepth(PointOfInstantiation, InstantiationRange);
281  if (!Invalid) {
282    ActiveTemplateInstantiation Inst;
283    Inst.Kind = ActiveTemplateInstantiation::DeducedTemplateArgumentSubstitution;
284    Inst.PointOfInstantiation = PointOfInstantiation;
285    Inst.Entity = PartialSpec;
286    Inst.TemplateArgs = TemplateArgs.data();
287    Inst.NumTemplateArgs = TemplateArgs.size();
288    Inst.DeductionInfo = &DeductionInfo;
289    Inst.InstantiationRange = InstantiationRange;
290    SemaRef.InNonInstantiationSFINAEContext = false;
291    SemaRef.ActiveTemplateInstantiations.push_back(Inst);
292  }
293}
294
295Sema::InstantiatingTemplate::
296InstantiatingTemplate(Sema &SemaRef, SourceLocation PointOfInstantiation,
297                      ParmVarDecl *Param,
298                      ArrayRef<TemplateArgument> TemplateArgs,
299                      SourceRange InstantiationRange)
300  : SemaRef(SemaRef),
301    SavedInNonInstantiationSFINAEContext(
302                                     SemaRef.InNonInstantiationSFINAEContext)
303{
304  Invalid = CheckInstantiationDepth(PointOfInstantiation, InstantiationRange);
305  if (!Invalid) {
306    ActiveTemplateInstantiation Inst;
307    Inst.Kind
308      = ActiveTemplateInstantiation::DefaultFunctionArgumentInstantiation;
309    Inst.PointOfInstantiation = PointOfInstantiation;
310    Inst.Entity = Param;
311    Inst.TemplateArgs = TemplateArgs.data();
312    Inst.NumTemplateArgs = TemplateArgs.size();
313    Inst.InstantiationRange = InstantiationRange;
314    SemaRef.InNonInstantiationSFINAEContext = false;
315    SemaRef.ActiveTemplateInstantiations.push_back(Inst);
316  }
317}
318
319Sema::InstantiatingTemplate::
320InstantiatingTemplate(Sema &SemaRef, SourceLocation PointOfInstantiation,
321                      NamedDecl *Template, NonTypeTemplateParmDecl *Param,
322                      ArrayRef<TemplateArgument> TemplateArgs,
323                      SourceRange InstantiationRange)
324  : SemaRef(SemaRef),
325    SavedInNonInstantiationSFINAEContext(
326                                     SemaRef.InNonInstantiationSFINAEContext)
327{
328  Invalid = CheckInstantiationDepth(PointOfInstantiation, InstantiationRange);
329  if (!Invalid) {
330    ActiveTemplateInstantiation Inst;
331    Inst.Kind = ActiveTemplateInstantiation::PriorTemplateArgumentSubstitution;
332    Inst.PointOfInstantiation = PointOfInstantiation;
333    Inst.Template = Template;
334    Inst.Entity = Param;
335    Inst.TemplateArgs = TemplateArgs.data();
336    Inst.NumTemplateArgs = TemplateArgs.size();
337    Inst.InstantiationRange = InstantiationRange;
338    SemaRef.InNonInstantiationSFINAEContext = false;
339    SemaRef.ActiveTemplateInstantiations.push_back(Inst);
340  }
341}
342
343Sema::InstantiatingTemplate::
344InstantiatingTemplate(Sema &SemaRef, SourceLocation PointOfInstantiation,
345                      NamedDecl *Template, TemplateTemplateParmDecl *Param,
346                      ArrayRef<TemplateArgument> TemplateArgs,
347                      SourceRange InstantiationRange)
348  : SemaRef(SemaRef),
349    SavedInNonInstantiationSFINAEContext(
350                                     SemaRef.InNonInstantiationSFINAEContext)
351{
352  Invalid = CheckInstantiationDepth(PointOfInstantiation, InstantiationRange);
353  if (!Invalid) {
354    ActiveTemplateInstantiation Inst;
355    Inst.Kind = ActiveTemplateInstantiation::PriorTemplateArgumentSubstitution;
356    Inst.PointOfInstantiation = PointOfInstantiation;
357    Inst.Template = Template;
358    Inst.Entity = Param;
359    Inst.TemplateArgs = TemplateArgs.data();
360    Inst.NumTemplateArgs = TemplateArgs.size();
361    Inst.InstantiationRange = InstantiationRange;
362    SemaRef.InNonInstantiationSFINAEContext = false;
363    SemaRef.ActiveTemplateInstantiations.push_back(Inst);
364  }
365}
366
367Sema::InstantiatingTemplate::
368InstantiatingTemplate(Sema &SemaRef, SourceLocation PointOfInstantiation,
369                      TemplateDecl *Template, NamedDecl *Param,
370                      ArrayRef<TemplateArgument> TemplateArgs,
371                      SourceRange InstantiationRange)
372  : SemaRef(SemaRef),
373    SavedInNonInstantiationSFINAEContext(
374                                     SemaRef.InNonInstantiationSFINAEContext)
375{
376  Invalid = false;
377
378  ActiveTemplateInstantiation Inst;
379  Inst.Kind = ActiveTemplateInstantiation::DefaultTemplateArgumentChecking;
380  Inst.PointOfInstantiation = PointOfInstantiation;
381  Inst.Template = Template;
382  Inst.Entity = Param;
383  Inst.TemplateArgs = TemplateArgs.data();
384  Inst.NumTemplateArgs = TemplateArgs.size();
385  Inst.InstantiationRange = InstantiationRange;
386  SemaRef.InNonInstantiationSFINAEContext = false;
387  SemaRef.ActiveTemplateInstantiations.push_back(Inst);
388
389  assert(!Inst.isInstantiationRecord());
390  ++SemaRef.NonInstantiationEntries;
391}
392
393void Sema::InstantiatingTemplate::Clear() {
394  if (!Invalid) {
395    if (!SemaRef.ActiveTemplateInstantiations.back().isInstantiationRecord()) {
396      assert(SemaRef.NonInstantiationEntries > 0);
397      --SemaRef.NonInstantiationEntries;
398    }
399    SemaRef.InNonInstantiationSFINAEContext
400      = SavedInNonInstantiationSFINAEContext;
401    SemaRef.ActiveTemplateInstantiations.pop_back();
402    Invalid = true;
403  }
404}
405
406bool Sema::InstantiatingTemplate::CheckInstantiationDepth(
407                                        SourceLocation PointOfInstantiation,
408                                           SourceRange InstantiationRange) {
409  assert(SemaRef.NonInstantiationEntries <=
410                                   SemaRef.ActiveTemplateInstantiations.size());
411  if ((SemaRef.ActiveTemplateInstantiations.size() -
412          SemaRef.NonInstantiationEntries)
413        <= SemaRef.getLangOpts().InstantiationDepth)
414    return false;
415
416  SemaRef.Diag(PointOfInstantiation,
417               diag::err_template_recursion_depth_exceeded)
418    << SemaRef.getLangOpts().InstantiationDepth
419    << InstantiationRange;
420  SemaRef.Diag(PointOfInstantiation, diag::note_template_recursion_depth)
421    << SemaRef.getLangOpts().InstantiationDepth;
422  return true;
423}
424
425/// \brief Prints the current instantiation stack through a series of
426/// notes.
427void Sema::PrintInstantiationStack() {
428  // Determine which template instantiations to skip, if any.
429  unsigned SkipStart = ActiveTemplateInstantiations.size(), SkipEnd = SkipStart;
430  unsigned Limit = Diags.getTemplateBacktraceLimit();
431  if (Limit && Limit < ActiveTemplateInstantiations.size()) {
432    SkipStart = Limit / 2 + Limit % 2;
433    SkipEnd = ActiveTemplateInstantiations.size() - Limit / 2;
434  }
435
436  // FIXME: In all of these cases, we need to show the template arguments
437  unsigned InstantiationIdx = 0;
438  for (SmallVector<ActiveTemplateInstantiation, 16>::reverse_iterator
439         Active = ActiveTemplateInstantiations.rbegin(),
440         ActiveEnd = ActiveTemplateInstantiations.rend();
441       Active != ActiveEnd;
442       ++Active, ++InstantiationIdx) {
443    // Skip this instantiation?
444    if (InstantiationIdx >= SkipStart && InstantiationIdx < SkipEnd) {
445      if (InstantiationIdx == SkipStart) {
446        // Note that we're skipping instantiations.
447        Diags.Report(Active->PointOfInstantiation,
448                     diag::note_instantiation_contexts_suppressed)
449          << unsigned(ActiveTemplateInstantiations.size() - Limit);
450      }
451      continue;
452    }
453
454    switch (Active->Kind) {
455    case ActiveTemplateInstantiation::TemplateInstantiation: {
456      Decl *D = Active->Entity;
457      if (CXXRecordDecl *Record = dyn_cast<CXXRecordDecl>(D)) {
458        unsigned DiagID = diag::note_template_member_class_here;
459        if (isa<ClassTemplateSpecializationDecl>(Record))
460          DiagID = diag::note_template_class_instantiation_here;
461        Diags.Report(Active->PointOfInstantiation, DiagID)
462          << Context.getTypeDeclType(Record)
463          << Active->InstantiationRange;
464      } else if (FunctionDecl *Function = dyn_cast<FunctionDecl>(D)) {
465        unsigned DiagID;
466        if (Function->getPrimaryTemplate())
467          DiagID = diag::note_function_template_spec_here;
468        else
469          DiagID = diag::note_template_member_function_here;
470        Diags.Report(Active->PointOfInstantiation, DiagID)
471          << Function
472          << Active->InstantiationRange;
473      } else if (VarDecl *VD = dyn_cast<VarDecl>(D)) {
474        Diags.Report(Active->PointOfInstantiation,
475                     diag::note_template_static_data_member_def_here)
476          << VD
477          << Active->InstantiationRange;
478      } else if (EnumDecl *ED = dyn_cast<EnumDecl>(D)) {
479        Diags.Report(Active->PointOfInstantiation,
480                     diag::note_template_enum_def_here)
481          << ED
482          << Active->InstantiationRange;
483      } else {
484        Diags.Report(Active->PointOfInstantiation,
485                     diag::note_template_type_alias_instantiation_here)
486          << cast<TypeAliasTemplateDecl>(D)
487          << Active->InstantiationRange;
488      }
489      break;
490    }
491
492    case ActiveTemplateInstantiation::DefaultTemplateArgumentInstantiation: {
493      TemplateDecl *Template = cast<TemplateDecl>(Active->Entity);
494      SmallVector<char, 128> TemplateArgsStr;
495      llvm::raw_svector_ostream OS(TemplateArgsStr);
496      Template->printName(OS);
497      TemplateSpecializationType::PrintTemplateArgumentList(OS,
498                                                         Active->TemplateArgs,
499                                                      Active->NumTemplateArgs,
500                                                      getPrintingPolicy());
501      Diags.Report(Active->PointOfInstantiation,
502                   diag::note_default_arg_instantiation_here)
503        << OS.str()
504        << Active->InstantiationRange;
505      break;
506    }
507
508    case ActiveTemplateInstantiation::ExplicitTemplateArgumentSubstitution: {
509      FunctionTemplateDecl *FnTmpl = cast<FunctionTemplateDecl>(Active->Entity);
510      Diags.Report(Active->PointOfInstantiation,
511                   diag::note_explicit_template_arg_substitution_here)
512        << FnTmpl
513        << getTemplateArgumentBindingsText(FnTmpl->getTemplateParameters(),
514                                           Active->TemplateArgs,
515                                           Active->NumTemplateArgs)
516        << Active->InstantiationRange;
517      break;
518    }
519
520    case ActiveTemplateInstantiation::DeducedTemplateArgumentSubstitution:
521      if (ClassTemplatePartialSpecializationDecl *PartialSpec =
522            dyn_cast<ClassTemplatePartialSpecializationDecl>(Active->Entity)) {
523        Diags.Report(Active->PointOfInstantiation,
524                     diag::note_partial_spec_deduct_instantiation_here)
525          << Context.getTypeDeclType(PartialSpec)
526          << getTemplateArgumentBindingsText(
527                                         PartialSpec->getTemplateParameters(),
528                                             Active->TemplateArgs,
529                                             Active->NumTemplateArgs)
530          << Active->InstantiationRange;
531      } else {
532        FunctionTemplateDecl *FnTmpl
533          = cast<FunctionTemplateDecl>(Active->Entity);
534        Diags.Report(Active->PointOfInstantiation,
535                     diag::note_function_template_deduction_instantiation_here)
536          << FnTmpl
537          << getTemplateArgumentBindingsText(FnTmpl->getTemplateParameters(),
538                                             Active->TemplateArgs,
539                                             Active->NumTemplateArgs)
540          << Active->InstantiationRange;
541      }
542      break;
543
544    case ActiveTemplateInstantiation::DefaultFunctionArgumentInstantiation: {
545      ParmVarDecl *Param = cast<ParmVarDecl>(Active->Entity);
546      FunctionDecl *FD = cast<FunctionDecl>(Param->getDeclContext());
547
548      SmallVector<char, 128> TemplateArgsStr;
549      llvm::raw_svector_ostream OS(TemplateArgsStr);
550      FD->printName(OS);
551      TemplateSpecializationType::PrintTemplateArgumentList(OS,
552                                                         Active->TemplateArgs,
553                                                      Active->NumTemplateArgs,
554                                                      getPrintingPolicy());
555      Diags.Report(Active->PointOfInstantiation,
556                   diag::note_default_function_arg_instantiation_here)
557        << OS.str()
558        << Active->InstantiationRange;
559      break;
560    }
561
562    case ActiveTemplateInstantiation::PriorTemplateArgumentSubstitution: {
563      NamedDecl *Parm = cast<NamedDecl>(Active->Entity);
564      std::string Name;
565      if (!Parm->getName().empty())
566        Name = std::string(" '") + Parm->getName().str() + "'";
567
568      TemplateParameterList *TemplateParams = 0;
569      if (TemplateDecl *Template = dyn_cast<TemplateDecl>(Active->Template))
570        TemplateParams = Template->getTemplateParameters();
571      else
572        TemplateParams =
573          cast<ClassTemplatePartialSpecializationDecl>(Active->Template)
574                                                      ->getTemplateParameters();
575      Diags.Report(Active->PointOfInstantiation,
576                   diag::note_prior_template_arg_substitution)
577        << isa<TemplateTemplateParmDecl>(Parm)
578        << Name
579        << getTemplateArgumentBindingsText(TemplateParams,
580                                           Active->TemplateArgs,
581                                           Active->NumTemplateArgs)
582        << Active->InstantiationRange;
583      break;
584    }
585
586    case ActiveTemplateInstantiation::DefaultTemplateArgumentChecking: {
587      TemplateParameterList *TemplateParams = 0;
588      if (TemplateDecl *Template = dyn_cast<TemplateDecl>(Active->Template))
589        TemplateParams = Template->getTemplateParameters();
590      else
591        TemplateParams =
592          cast<ClassTemplatePartialSpecializationDecl>(Active->Template)
593                                                      ->getTemplateParameters();
594
595      Diags.Report(Active->PointOfInstantiation,
596                   diag::note_template_default_arg_checking)
597        << getTemplateArgumentBindingsText(TemplateParams,
598                                           Active->TemplateArgs,
599                                           Active->NumTemplateArgs)
600        << Active->InstantiationRange;
601      break;
602    }
603
604    case ActiveTemplateInstantiation::ExceptionSpecInstantiation:
605      Diags.Report(Active->PointOfInstantiation,
606                   diag::note_template_exception_spec_instantiation_here)
607        << cast<FunctionDecl>(Active->Entity)
608        << Active->InstantiationRange;
609      break;
610    }
611  }
612}
613
614Optional<TemplateDeductionInfo *> Sema::isSFINAEContext() const {
615  if (InNonInstantiationSFINAEContext)
616    return Optional<TemplateDeductionInfo *>(0);
617
618  for (SmallVector<ActiveTemplateInstantiation, 16>::const_reverse_iterator
619         Active = ActiveTemplateInstantiations.rbegin(),
620         ActiveEnd = ActiveTemplateInstantiations.rend();
621       Active != ActiveEnd;
622       ++Active)
623  {
624    switch(Active->Kind) {
625    case ActiveTemplateInstantiation::TemplateInstantiation:
626      // An instantiation of an alias template may or may not be a SFINAE
627      // context, depending on what else is on the stack.
628      if (isa<TypeAliasTemplateDecl>(Active->Entity))
629        break;
630      // Fall through.
631    case ActiveTemplateInstantiation::DefaultFunctionArgumentInstantiation:
632    case ActiveTemplateInstantiation::ExceptionSpecInstantiation:
633      // This is a template instantiation, so there is no SFINAE.
634      return None;
635
636    case ActiveTemplateInstantiation::DefaultTemplateArgumentInstantiation:
637    case ActiveTemplateInstantiation::PriorTemplateArgumentSubstitution:
638    case ActiveTemplateInstantiation::DefaultTemplateArgumentChecking:
639      // A default template argument instantiation and substitution into
640      // template parameters with arguments for prior parameters may or may
641      // not be a SFINAE context; look further up the stack.
642      break;
643
644    case ActiveTemplateInstantiation::ExplicitTemplateArgumentSubstitution:
645    case ActiveTemplateInstantiation::DeducedTemplateArgumentSubstitution:
646      // We're either substitution explicitly-specified template arguments
647      // or deduced template arguments, so SFINAE applies.
648      assert(Active->DeductionInfo && "Missing deduction info pointer");
649      return Active->DeductionInfo;
650    }
651  }
652
653  return None;
654}
655
656/// \brief Retrieve the depth and index of a parameter pack.
657static std::pair<unsigned, unsigned>
658getDepthAndIndex(NamedDecl *ND) {
659  if (TemplateTypeParmDecl *TTP = dyn_cast<TemplateTypeParmDecl>(ND))
660    return std::make_pair(TTP->getDepth(), TTP->getIndex());
661
662  if (NonTypeTemplateParmDecl *NTTP = dyn_cast<NonTypeTemplateParmDecl>(ND))
663    return std::make_pair(NTTP->getDepth(), NTTP->getIndex());
664
665  TemplateTemplateParmDecl *TTP = cast<TemplateTemplateParmDecl>(ND);
666  return std::make_pair(TTP->getDepth(), TTP->getIndex());
667}
668
669//===----------------------------------------------------------------------===/
670// Template Instantiation for Types
671//===----------------------------------------------------------------------===/
672namespace {
673  class TemplateInstantiator : public TreeTransform<TemplateInstantiator> {
674    const MultiLevelTemplateArgumentList &TemplateArgs;
675    SourceLocation Loc;
676    DeclarationName Entity;
677
678  public:
679    typedef TreeTransform<TemplateInstantiator> inherited;
680
681    TemplateInstantiator(Sema &SemaRef,
682                         const MultiLevelTemplateArgumentList &TemplateArgs,
683                         SourceLocation Loc,
684                         DeclarationName Entity)
685      : inherited(SemaRef), TemplateArgs(TemplateArgs), Loc(Loc),
686        Entity(Entity) { }
687
688    /// \brief Determine whether the given type \p T has already been
689    /// transformed.
690    ///
691    /// For the purposes of template instantiation, a type has already been
692    /// transformed if it is NULL or if it is not dependent.
693    bool AlreadyTransformed(QualType T);
694
695    /// \brief Returns the location of the entity being instantiated, if known.
696    SourceLocation getBaseLocation() { return Loc; }
697
698    /// \brief Returns the name of the entity being instantiated, if any.
699    DeclarationName getBaseEntity() { return Entity; }
700
701    /// \brief Sets the "base" location and entity when that
702    /// information is known based on another transformation.
703    void setBase(SourceLocation Loc, DeclarationName Entity) {
704      this->Loc = Loc;
705      this->Entity = Entity;
706    }
707
708    bool TryExpandParameterPacks(SourceLocation EllipsisLoc,
709                                 SourceRange PatternRange,
710                             llvm::ArrayRef<UnexpandedParameterPack> Unexpanded,
711                                 bool &ShouldExpand,
712                                 bool &RetainExpansion,
713                                 Optional<unsigned> &NumExpansions) {
714      return getSema().CheckParameterPacksForExpansion(EllipsisLoc,
715                                                       PatternRange, Unexpanded,
716                                                       TemplateArgs,
717                                                       ShouldExpand,
718                                                       RetainExpansion,
719                                                       NumExpansions);
720    }
721
722    void ExpandingFunctionParameterPack(ParmVarDecl *Pack) {
723      SemaRef.CurrentInstantiationScope->MakeInstantiatedLocalArgPack(Pack);
724    }
725
726    TemplateArgument ForgetPartiallySubstitutedPack() {
727      TemplateArgument Result;
728      if (NamedDecl *PartialPack
729            = SemaRef.CurrentInstantiationScope->getPartiallySubstitutedPack()){
730        MultiLevelTemplateArgumentList &TemplateArgs
731          = const_cast<MultiLevelTemplateArgumentList &>(this->TemplateArgs);
732        unsigned Depth, Index;
733        llvm::tie(Depth, Index) = getDepthAndIndex(PartialPack);
734        if (TemplateArgs.hasTemplateArgument(Depth, Index)) {
735          Result = TemplateArgs(Depth, Index);
736          TemplateArgs.setArgument(Depth, Index, TemplateArgument());
737        }
738      }
739
740      return Result;
741    }
742
743    void RememberPartiallySubstitutedPack(TemplateArgument Arg) {
744      if (Arg.isNull())
745        return;
746
747      if (NamedDecl *PartialPack
748            = SemaRef.CurrentInstantiationScope->getPartiallySubstitutedPack()){
749        MultiLevelTemplateArgumentList &TemplateArgs
750        = const_cast<MultiLevelTemplateArgumentList &>(this->TemplateArgs);
751        unsigned Depth, Index;
752        llvm::tie(Depth, Index) = getDepthAndIndex(PartialPack);
753        TemplateArgs.setArgument(Depth, Index, Arg);
754      }
755    }
756
757    /// \brief Transform the given declaration by instantiating a reference to
758    /// this declaration.
759    Decl *TransformDecl(SourceLocation Loc, Decl *D);
760
761    void transformAttrs(Decl *Old, Decl *New) {
762      SemaRef.InstantiateAttrs(TemplateArgs, Old, New);
763    }
764
765    void transformedLocalDecl(Decl *Old, Decl *New) {
766      SemaRef.CurrentInstantiationScope->InstantiatedLocal(Old, New);
767    }
768
769    /// \brief Transform the definition of the given declaration by
770    /// instantiating it.
771    Decl *TransformDefinition(SourceLocation Loc, Decl *D);
772
773    /// \brief Transform the first qualifier within a scope by instantiating the
774    /// declaration.
775    NamedDecl *TransformFirstQualifierInScope(NamedDecl *D, SourceLocation Loc);
776
777    /// \brief Rebuild the exception declaration and register the declaration
778    /// as an instantiated local.
779    VarDecl *RebuildExceptionDecl(VarDecl *ExceptionDecl,
780                                  TypeSourceInfo *Declarator,
781                                  SourceLocation StartLoc,
782                                  SourceLocation NameLoc,
783                                  IdentifierInfo *Name);
784
785    /// \brief Rebuild the Objective-C exception declaration and register the
786    /// declaration as an instantiated local.
787    VarDecl *RebuildObjCExceptionDecl(VarDecl *ExceptionDecl,
788                                      TypeSourceInfo *TSInfo, QualType T);
789
790    /// \brief Check for tag mismatches when instantiating an
791    /// elaborated type.
792    QualType RebuildElaboratedType(SourceLocation KeywordLoc,
793                                   ElaboratedTypeKeyword Keyword,
794                                   NestedNameSpecifierLoc QualifierLoc,
795                                   QualType T);
796
797    TemplateName TransformTemplateName(CXXScopeSpec &SS,
798                                       TemplateName Name,
799                                       SourceLocation NameLoc,
800                                       QualType ObjectType = QualType(),
801                                       NamedDecl *FirstQualifierInScope = 0);
802
803    ExprResult TransformPredefinedExpr(PredefinedExpr *E);
804    ExprResult TransformDeclRefExpr(DeclRefExpr *E);
805    ExprResult TransformCXXDefaultArgExpr(CXXDefaultArgExpr *E);
806
807    ExprResult TransformTemplateParmRefExpr(DeclRefExpr *E,
808                                            NonTypeTemplateParmDecl *D);
809    ExprResult TransformSubstNonTypeTemplateParmPackExpr(
810                                           SubstNonTypeTemplateParmPackExpr *E);
811
812    /// \brief Rebuild a DeclRefExpr for a ParmVarDecl reference.
813    ExprResult RebuildParmVarDeclRefExpr(ParmVarDecl *PD, SourceLocation Loc);
814
815    /// \brief Transform a reference to a function parameter pack.
816    ExprResult TransformFunctionParmPackRefExpr(DeclRefExpr *E,
817                                                ParmVarDecl *PD);
818
819    /// \brief Transform a FunctionParmPackExpr which was built when we couldn't
820    /// expand a function parameter pack reference which refers to an expanded
821    /// pack.
822    ExprResult TransformFunctionParmPackExpr(FunctionParmPackExpr *E);
823
824    QualType TransformFunctionProtoType(TypeLocBuilder &TLB,
825                                        FunctionProtoTypeLoc TL);
826    QualType TransformFunctionProtoType(TypeLocBuilder &TLB,
827                                        FunctionProtoTypeLoc TL,
828                                        CXXRecordDecl *ThisContext,
829                                        unsigned ThisTypeQuals);
830
831    ParmVarDecl *TransformFunctionTypeParam(ParmVarDecl *OldParm,
832                                            int indexAdjustment,
833                                            Optional<unsigned> NumExpansions,
834                                            bool ExpectParameterPack);
835
836    /// \brief Transforms a template type parameter type by performing
837    /// substitution of the corresponding template type argument.
838    QualType TransformTemplateTypeParmType(TypeLocBuilder &TLB,
839                                           TemplateTypeParmTypeLoc TL);
840
841    /// \brief Transforms an already-substituted template type parameter pack
842    /// into either itself (if we aren't substituting into its pack expansion)
843    /// or the appropriate substituted argument.
844    QualType TransformSubstTemplateTypeParmPackType(TypeLocBuilder &TLB,
845                                           SubstTemplateTypeParmPackTypeLoc TL);
846
847    ExprResult TransformCallExpr(CallExpr *CE) {
848      getSema().CallsUndergoingInstantiation.push_back(CE);
849      ExprResult Result =
850          TreeTransform<TemplateInstantiator>::TransformCallExpr(CE);
851      getSema().CallsUndergoingInstantiation.pop_back();
852      return Result;
853    }
854
855    ExprResult TransformLambdaExpr(LambdaExpr *E) {
856      LocalInstantiationScope Scope(SemaRef, /*CombineWithOuterScope=*/true);
857      return TreeTransform<TemplateInstantiator>::TransformLambdaExpr(E);
858    }
859
860    ExprResult TransformLambdaScope(LambdaExpr *E,
861                                    CXXMethodDecl *CallOperator) {
862      CallOperator->setInstantiationOfMemberFunction(E->getCallOperator(),
863                                                     TSK_ImplicitInstantiation);
864      return TreeTransform<TemplateInstantiator>::
865         TransformLambdaScope(E, CallOperator);
866    }
867
868  private:
869    ExprResult transformNonTypeTemplateParmRef(NonTypeTemplateParmDecl *parm,
870                                               SourceLocation loc,
871                                               TemplateArgument arg);
872  };
873}
874
875bool TemplateInstantiator::AlreadyTransformed(QualType T) {
876  if (T.isNull())
877    return true;
878
879  if (T->isInstantiationDependentType() || T->isVariablyModifiedType())
880    return false;
881
882  getSema().MarkDeclarationsReferencedInType(Loc, T);
883  return true;
884}
885
886Decl *TemplateInstantiator::TransformDecl(SourceLocation Loc, Decl *D) {
887  if (!D)
888    return 0;
889
890  if (TemplateTemplateParmDecl *TTP = dyn_cast<TemplateTemplateParmDecl>(D)) {
891    if (TTP->getDepth() < TemplateArgs.getNumLevels()) {
892      // If the corresponding template argument is NULL or non-existent, it's
893      // because we are performing instantiation from explicitly-specified
894      // template arguments in a function template, but there were some
895      // arguments left unspecified.
896      if (!TemplateArgs.hasTemplateArgument(TTP->getDepth(),
897                                            TTP->getPosition()))
898        return D;
899
900      TemplateArgument Arg = TemplateArgs(TTP->getDepth(), TTP->getPosition());
901
902      if (TTP->isParameterPack()) {
903        assert(Arg.getKind() == TemplateArgument::Pack &&
904               "Missing argument pack");
905
906        assert(getSema().ArgumentPackSubstitutionIndex >= 0);
907        assert(getSema().ArgumentPackSubstitutionIndex < (int)Arg.pack_size());
908        Arg = Arg.pack_begin()[getSema().ArgumentPackSubstitutionIndex];
909      }
910
911      TemplateName Template = Arg.getAsTemplate();
912      assert(!Template.isNull() && Template.getAsTemplateDecl() &&
913             "Wrong kind of template template argument");
914      return Template.getAsTemplateDecl();
915    }
916
917    // Fall through to find the instantiated declaration for this template
918    // template parameter.
919  }
920
921  return SemaRef.FindInstantiatedDecl(Loc, cast<NamedDecl>(D), TemplateArgs);
922}
923
924Decl *TemplateInstantiator::TransformDefinition(SourceLocation Loc, Decl *D) {
925  Decl *Inst = getSema().SubstDecl(D, getSema().CurContext, TemplateArgs);
926  if (!Inst)
927    return 0;
928
929  getSema().CurrentInstantiationScope->InstantiatedLocal(D, Inst);
930  return Inst;
931}
932
933NamedDecl *
934TemplateInstantiator::TransformFirstQualifierInScope(NamedDecl *D,
935                                                     SourceLocation Loc) {
936  // If the first part of the nested-name-specifier was a template type
937  // parameter, instantiate that type parameter down to a tag type.
938  if (TemplateTypeParmDecl *TTPD = dyn_cast_or_null<TemplateTypeParmDecl>(D)) {
939    const TemplateTypeParmType *TTP
940      = cast<TemplateTypeParmType>(getSema().Context.getTypeDeclType(TTPD));
941
942    if (TTP->getDepth() < TemplateArgs.getNumLevels()) {
943      // FIXME: This needs testing w/ member access expressions.
944      TemplateArgument Arg = TemplateArgs(TTP->getDepth(), TTP->getIndex());
945
946      if (TTP->isParameterPack()) {
947        assert(Arg.getKind() == TemplateArgument::Pack &&
948               "Missing argument pack");
949
950        if (getSema().ArgumentPackSubstitutionIndex == -1)
951          return 0;
952
953        assert(getSema().ArgumentPackSubstitutionIndex < (int)Arg.pack_size());
954        Arg = Arg.pack_begin()[getSema().ArgumentPackSubstitutionIndex];
955      }
956
957      QualType T = Arg.getAsType();
958      if (T.isNull())
959        return cast_or_null<NamedDecl>(TransformDecl(Loc, D));
960
961      if (const TagType *Tag = T->getAs<TagType>())
962        return Tag->getDecl();
963
964      // The resulting type is not a tag; complain.
965      getSema().Diag(Loc, diag::err_nested_name_spec_non_tag) << T;
966      return 0;
967    }
968  }
969
970  return cast_or_null<NamedDecl>(TransformDecl(Loc, D));
971}
972
973VarDecl *
974TemplateInstantiator::RebuildExceptionDecl(VarDecl *ExceptionDecl,
975                                           TypeSourceInfo *Declarator,
976                                           SourceLocation StartLoc,
977                                           SourceLocation NameLoc,
978                                           IdentifierInfo *Name) {
979  VarDecl *Var = inherited::RebuildExceptionDecl(ExceptionDecl, Declarator,
980                                                 StartLoc, NameLoc, Name);
981  if (Var)
982    getSema().CurrentInstantiationScope->InstantiatedLocal(ExceptionDecl, Var);
983  return Var;
984}
985
986VarDecl *TemplateInstantiator::RebuildObjCExceptionDecl(VarDecl *ExceptionDecl,
987                                                        TypeSourceInfo *TSInfo,
988                                                        QualType T) {
989  VarDecl *Var = inherited::RebuildObjCExceptionDecl(ExceptionDecl, TSInfo, T);
990  if (Var)
991    getSema().CurrentInstantiationScope->InstantiatedLocal(ExceptionDecl, Var);
992  return Var;
993}
994
995QualType
996TemplateInstantiator::RebuildElaboratedType(SourceLocation KeywordLoc,
997                                            ElaboratedTypeKeyword Keyword,
998                                            NestedNameSpecifierLoc QualifierLoc,
999                                            QualType T) {
1000  if (const TagType *TT = T->getAs<TagType>()) {
1001    TagDecl* TD = TT->getDecl();
1002
1003    SourceLocation TagLocation = KeywordLoc;
1004
1005    IdentifierInfo *Id = TD->getIdentifier();
1006
1007    // TODO: should we even warn on struct/class mismatches for this?  Seems
1008    // like it's likely to produce a lot of spurious errors.
1009    if (Id && Keyword != ETK_None && Keyword != ETK_Typename) {
1010      TagTypeKind Kind = TypeWithKeyword::getTagTypeKindForKeyword(Keyword);
1011      if (!SemaRef.isAcceptableTagRedeclaration(TD, Kind, /*isDefinition*/false,
1012                                                TagLocation, *Id)) {
1013        SemaRef.Diag(TagLocation, diag::err_use_with_wrong_tag)
1014          << Id
1015          << FixItHint::CreateReplacement(SourceRange(TagLocation),
1016                                          TD->getKindName());
1017        SemaRef.Diag(TD->getLocation(), diag::note_previous_use);
1018      }
1019    }
1020  }
1021
1022  return TreeTransform<TemplateInstantiator>::RebuildElaboratedType(KeywordLoc,
1023                                                                    Keyword,
1024                                                                  QualifierLoc,
1025                                                                    T);
1026}
1027
1028TemplateName TemplateInstantiator::TransformTemplateName(CXXScopeSpec &SS,
1029                                                         TemplateName Name,
1030                                                         SourceLocation NameLoc,
1031                                                         QualType ObjectType,
1032                                             NamedDecl *FirstQualifierInScope) {
1033  if (TemplateTemplateParmDecl *TTP
1034       = dyn_cast_or_null<TemplateTemplateParmDecl>(Name.getAsTemplateDecl())) {
1035    if (TTP->getDepth() < TemplateArgs.getNumLevels()) {
1036      // If the corresponding template argument is NULL or non-existent, it's
1037      // because we are performing instantiation from explicitly-specified
1038      // template arguments in a function template, but there were some
1039      // arguments left unspecified.
1040      if (!TemplateArgs.hasTemplateArgument(TTP->getDepth(),
1041                                            TTP->getPosition()))
1042        return Name;
1043
1044      TemplateArgument Arg = TemplateArgs(TTP->getDepth(), TTP->getPosition());
1045
1046      if (TTP->isParameterPack()) {
1047        assert(Arg.getKind() == TemplateArgument::Pack &&
1048               "Missing argument pack");
1049
1050        if (getSema().ArgumentPackSubstitutionIndex == -1) {
1051          // We have the template argument pack to substitute, but we're not
1052          // actually expanding the enclosing pack expansion yet. So, just
1053          // keep the entire argument pack.
1054          return getSema().Context.getSubstTemplateTemplateParmPack(TTP, Arg);
1055        }
1056
1057        assert(getSema().ArgumentPackSubstitutionIndex < (int)Arg.pack_size());
1058        Arg = Arg.pack_begin()[getSema().ArgumentPackSubstitutionIndex];
1059      }
1060
1061      TemplateName Template = Arg.getAsTemplate();
1062      assert(!Template.isNull() && "Null template template argument");
1063
1064      // We don't ever want to substitute for a qualified template name, since
1065      // the qualifier is handled separately. So, look through the qualified
1066      // template name to its underlying declaration.
1067      if (QualifiedTemplateName *QTN = Template.getAsQualifiedTemplateName())
1068        Template = TemplateName(QTN->getTemplateDecl());
1069
1070      Template = getSema().Context.getSubstTemplateTemplateParm(TTP, Template);
1071      return Template;
1072    }
1073  }
1074
1075  if (SubstTemplateTemplateParmPackStorage *SubstPack
1076      = Name.getAsSubstTemplateTemplateParmPack()) {
1077    if (getSema().ArgumentPackSubstitutionIndex == -1)
1078      return Name;
1079
1080    const TemplateArgument &ArgPack = SubstPack->getArgumentPack();
1081    assert(getSema().ArgumentPackSubstitutionIndex < (int)ArgPack.pack_size() &&
1082           "Pack substitution index out-of-range");
1083    return ArgPack.pack_begin()[getSema().ArgumentPackSubstitutionIndex]
1084    .getAsTemplate();
1085  }
1086
1087  return inherited::TransformTemplateName(SS, Name, NameLoc, ObjectType,
1088                                          FirstQualifierInScope);
1089}
1090
1091ExprResult
1092TemplateInstantiator::TransformPredefinedExpr(PredefinedExpr *E) {
1093  if (!E->isTypeDependent())
1094    return SemaRef.Owned(E);
1095
1096  FunctionDecl *currentDecl = getSema().getCurFunctionDecl();
1097  assert(currentDecl && "Must have current function declaration when "
1098                        "instantiating.");
1099
1100  PredefinedExpr::IdentType IT = E->getIdentType();
1101
1102  unsigned Length = PredefinedExpr::ComputeName(IT, currentDecl).length();
1103
1104  llvm::APInt LengthI(32, Length + 1);
1105  QualType ResTy;
1106  if (IT == PredefinedExpr::LFunction)
1107    ResTy = getSema().Context.WideCharTy.withConst();
1108  else
1109    ResTy = getSema().Context.CharTy.withConst();
1110  ResTy = getSema().Context.getConstantArrayType(ResTy, LengthI,
1111                                                 ArrayType::Normal, 0);
1112  PredefinedExpr *PE =
1113    new (getSema().Context) PredefinedExpr(E->getLocation(), ResTy, IT);
1114  return getSema().Owned(PE);
1115}
1116
1117ExprResult
1118TemplateInstantiator::TransformTemplateParmRefExpr(DeclRefExpr *E,
1119                                               NonTypeTemplateParmDecl *NTTP) {
1120  // If the corresponding template argument is NULL or non-existent, it's
1121  // because we are performing instantiation from explicitly-specified
1122  // template arguments in a function template, but there were some
1123  // arguments left unspecified.
1124  if (!TemplateArgs.hasTemplateArgument(NTTP->getDepth(),
1125                                        NTTP->getPosition()))
1126    return SemaRef.Owned(E);
1127
1128  TemplateArgument Arg = TemplateArgs(NTTP->getDepth(), NTTP->getPosition());
1129  if (NTTP->isParameterPack()) {
1130    assert(Arg.getKind() == TemplateArgument::Pack &&
1131           "Missing argument pack");
1132
1133    if (getSema().ArgumentPackSubstitutionIndex == -1) {
1134      // We have an argument pack, but we can't select a particular argument
1135      // out of it yet. Therefore, we'll build an expression to hold on to that
1136      // argument pack.
1137      QualType TargetType = SemaRef.SubstType(NTTP->getType(), TemplateArgs,
1138                                              E->getLocation(),
1139                                              NTTP->getDeclName());
1140      if (TargetType.isNull())
1141        return ExprError();
1142
1143      return new (SemaRef.Context) SubstNonTypeTemplateParmPackExpr(TargetType,
1144                                                                    NTTP,
1145                                                              E->getLocation(),
1146                                                                    Arg);
1147    }
1148
1149    assert(getSema().ArgumentPackSubstitutionIndex < (int)Arg.pack_size());
1150    Arg = Arg.pack_begin()[getSema().ArgumentPackSubstitutionIndex];
1151  }
1152
1153  return transformNonTypeTemplateParmRef(NTTP, E->getLocation(), Arg);
1154}
1155
1156ExprResult TemplateInstantiator::transformNonTypeTemplateParmRef(
1157                                                 NonTypeTemplateParmDecl *parm,
1158                                                 SourceLocation loc,
1159                                                 TemplateArgument arg) {
1160  ExprResult result;
1161  QualType type;
1162
1163  // If the argument is a pack expansion, the parameter must actually be a
1164  // parameter pack, and we should substitute the pattern itself, producing
1165  // an expression which contains an unexpanded parameter pack.
1166  if (arg.isPackExpansion()) {
1167    assert(parm->isParameterPack() && "pack expansion for non-pack");
1168    arg = arg.getPackExpansionPattern();
1169  }
1170
1171  // The template argument itself might be an expression, in which
1172  // case we just return that expression.
1173  if (arg.getKind() == TemplateArgument::Expression) {
1174    Expr *argExpr = arg.getAsExpr();
1175    result = SemaRef.Owned(argExpr);
1176    type = argExpr->getType();
1177
1178  } else if (arg.getKind() == TemplateArgument::Declaration ||
1179             arg.getKind() == TemplateArgument::NullPtr) {
1180    ValueDecl *VD;
1181    if (arg.getKind() == TemplateArgument::Declaration) {
1182      VD = cast<ValueDecl>(arg.getAsDecl());
1183
1184      // Find the instantiation of the template argument.  This is
1185      // required for nested templates.
1186      VD = cast_or_null<ValueDecl>(
1187             getSema().FindInstantiatedDecl(loc, VD, TemplateArgs));
1188      if (!VD)
1189        return ExprError();
1190    } else {
1191      // Propagate NULL template argument.
1192      VD = 0;
1193    }
1194
1195    // Derive the type we want the substituted decl to have.  This had
1196    // better be non-dependent, or these checks will have serious problems.
1197    if (parm->isExpandedParameterPack()) {
1198      type = parm->getExpansionType(SemaRef.ArgumentPackSubstitutionIndex);
1199    } else if (parm->isParameterPack() &&
1200               isa<PackExpansionType>(parm->getType())) {
1201      type = SemaRef.SubstType(
1202                        cast<PackExpansionType>(parm->getType())->getPattern(),
1203                                     TemplateArgs, loc, parm->getDeclName());
1204    } else {
1205      type = SemaRef.SubstType(parm->getType(), TemplateArgs,
1206                               loc, parm->getDeclName());
1207    }
1208    assert(!type.isNull() && "type substitution failed for param type");
1209    assert(!type->isDependentType() && "param type still dependent");
1210    result = SemaRef.BuildExpressionFromDeclTemplateArgument(arg, type, loc);
1211
1212    if (!result.isInvalid()) type = result.get()->getType();
1213  } else {
1214    result = SemaRef.BuildExpressionFromIntegralTemplateArgument(arg, loc);
1215
1216    // Note that this type can be different from the type of 'result',
1217    // e.g. if it's an enum type.
1218    type = arg.getIntegralType();
1219  }
1220  if (result.isInvalid()) return ExprError();
1221
1222  Expr *resultExpr = result.take();
1223  return SemaRef.Owned(new (SemaRef.Context)
1224                SubstNonTypeTemplateParmExpr(type,
1225                                             resultExpr->getValueKind(),
1226                                             loc, parm, resultExpr));
1227}
1228
1229ExprResult
1230TemplateInstantiator::TransformSubstNonTypeTemplateParmPackExpr(
1231                                          SubstNonTypeTemplateParmPackExpr *E) {
1232  if (getSema().ArgumentPackSubstitutionIndex == -1) {
1233    // We aren't expanding the parameter pack, so just return ourselves.
1234    return getSema().Owned(E);
1235  }
1236
1237  const TemplateArgument &ArgPack = E->getArgumentPack();
1238  unsigned Index = (unsigned)getSema().ArgumentPackSubstitutionIndex;
1239  assert(Index < ArgPack.pack_size() && "Substitution index out-of-range");
1240
1241  const TemplateArgument &Arg = ArgPack.pack_begin()[Index];
1242  return transformNonTypeTemplateParmRef(E->getParameterPack(),
1243                                         E->getParameterPackLocation(),
1244                                         Arg);
1245}
1246
1247ExprResult
1248TemplateInstantiator::RebuildParmVarDeclRefExpr(ParmVarDecl *PD,
1249                                                SourceLocation Loc) {
1250  DeclarationNameInfo NameInfo(PD->getDeclName(), Loc);
1251  return getSema().BuildDeclarationNameExpr(CXXScopeSpec(), NameInfo, PD);
1252}
1253
1254ExprResult
1255TemplateInstantiator::TransformFunctionParmPackExpr(FunctionParmPackExpr *E) {
1256  if (getSema().ArgumentPackSubstitutionIndex != -1) {
1257    // We can expand this parameter pack now.
1258    ParmVarDecl *D = E->getExpansion(getSema().ArgumentPackSubstitutionIndex);
1259    ValueDecl *VD = cast_or_null<ValueDecl>(TransformDecl(E->getExprLoc(), D));
1260    if (!VD)
1261      return ExprError();
1262    return RebuildParmVarDeclRefExpr(cast<ParmVarDecl>(VD), E->getExprLoc());
1263  }
1264
1265  QualType T = TransformType(E->getType());
1266  if (T.isNull())
1267    return ExprError();
1268
1269  // Transform each of the parameter expansions into the corresponding
1270  // parameters in the instantiation of the function decl.
1271  SmallVector<Decl *, 8> Parms;
1272  Parms.reserve(E->getNumExpansions());
1273  for (FunctionParmPackExpr::iterator I = E->begin(), End = E->end();
1274       I != End; ++I) {
1275    ParmVarDecl *D =
1276        cast_or_null<ParmVarDecl>(TransformDecl(E->getExprLoc(), *I));
1277    if (!D)
1278      return ExprError();
1279    Parms.push_back(D);
1280  }
1281
1282  return FunctionParmPackExpr::Create(getSema().Context, T,
1283                                      E->getParameterPack(),
1284                                      E->getParameterPackLocation(), Parms);
1285}
1286
1287ExprResult
1288TemplateInstantiator::TransformFunctionParmPackRefExpr(DeclRefExpr *E,
1289                                                       ParmVarDecl *PD) {
1290  typedef LocalInstantiationScope::DeclArgumentPack DeclArgumentPack;
1291  llvm::PointerUnion<Decl *, DeclArgumentPack *> *Found
1292    = getSema().CurrentInstantiationScope->findInstantiationOf(PD);
1293  assert(Found && "no instantiation for parameter pack");
1294
1295  Decl *TransformedDecl;
1296  if (DeclArgumentPack *Pack = Found->dyn_cast<DeclArgumentPack *>()) {
1297    // If this is a reference to a function parameter pack which we can substitute
1298    // but can't yet expand, build a FunctionParmPackExpr for it.
1299    if (getSema().ArgumentPackSubstitutionIndex == -1) {
1300      QualType T = TransformType(E->getType());
1301      if (T.isNull())
1302        return ExprError();
1303      return FunctionParmPackExpr::Create(getSema().Context, T, PD,
1304                                          E->getExprLoc(), *Pack);
1305    }
1306
1307    TransformedDecl = (*Pack)[getSema().ArgumentPackSubstitutionIndex];
1308  } else {
1309    TransformedDecl = Found->get<Decl*>();
1310  }
1311
1312  // We have either an unexpanded pack or a specific expansion.
1313  return RebuildParmVarDeclRefExpr(cast<ParmVarDecl>(TransformedDecl),
1314                                   E->getExprLoc());
1315}
1316
1317ExprResult
1318TemplateInstantiator::TransformDeclRefExpr(DeclRefExpr *E) {
1319  NamedDecl *D = E->getDecl();
1320
1321  // Handle references to non-type template parameters and non-type template
1322  // parameter packs.
1323  if (NonTypeTemplateParmDecl *NTTP = dyn_cast<NonTypeTemplateParmDecl>(D)) {
1324    if (NTTP->getDepth() < TemplateArgs.getNumLevels())
1325      return TransformTemplateParmRefExpr(E, NTTP);
1326
1327    // We have a non-type template parameter that isn't fully substituted;
1328    // FindInstantiatedDecl will find it in the local instantiation scope.
1329  }
1330
1331  // Handle references to function parameter packs.
1332  if (ParmVarDecl *PD = dyn_cast<ParmVarDecl>(D))
1333    if (PD->isParameterPack())
1334      return TransformFunctionParmPackRefExpr(E, PD);
1335
1336  return TreeTransform<TemplateInstantiator>::TransformDeclRefExpr(E);
1337}
1338
1339ExprResult TemplateInstantiator::TransformCXXDefaultArgExpr(
1340    CXXDefaultArgExpr *E) {
1341  assert(!cast<FunctionDecl>(E->getParam()->getDeclContext())->
1342             getDescribedFunctionTemplate() &&
1343         "Default arg expressions are never formed in dependent cases.");
1344  return SemaRef.BuildCXXDefaultArgExpr(E->getUsedLocation(),
1345                           cast<FunctionDecl>(E->getParam()->getDeclContext()),
1346                                        E->getParam());
1347}
1348
1349QualType TemplateInstantiator::TransformFunctionProtoType(TypeLocBuilder &TLB,
1350                                                      FunctionProtoTypeLoc TL) {
1351  // We need a local instantiation scope for this function prototype.
1352  LocalInstantiationScope Scope(SemaRef, /*CombineWithOuterScope=*/true);
1353  return inherited::TransformFunctionProtoType(TLB, TL);
1354}
1355
1356QualType TemplateInstantiator::TransformFunctionProtoType(TypeLocBuilder &TLB,
1357                                 FunctionProtoTypeLoc TL,
1358                                 CXXRecordDecl *ThisContext,
1359                                 unsigned ThisTypeQuals) {
1360  // We need a local instantiation scope for this function prototype.
1361  LocalInstantiationScope Scope(SemaRef, /*CombineWithOuterScope=*/true);
1362  return inherited::TransformFunctionProtoType(TLB, TL, ThisContext,
1363                                               ThisTypeQuals);
1364}
1365
1366ParmVarDecl *
1367TemplateInstantiator::TransformFunctionTypeParam(ParmVarDecl *OldParm,
1368                                                 int indexAdjustment,
1369                                               Optional<unsigned> NumExpansions,
1370                                                 bool ExpectParameterPack) {
1371  return SemaRef.SubstParmVarDecl(OldParm, TemplateArgs, indexAdjustment,
1372                                  NumExpansions, ExpectParameterPack);
1373}
1374
1375QualType
1376TemplateInstantiator::TransformTemplateTypeParmType(TypeLocBuilder &TLB,
1377                                                TemplateTypeParmTypeLoc TL) {
1378  const TemplateTypeParmType *T = TL.getTypePtr();
1379  if (T->getDepth() < TemplateArgs.getNumLevels()) {
1380    // Replace the template type parameter with its corresponding
1381    // template argument.
1382
1383    // If the corresponding template argument is NULL or doesn't exist, it's
1384    // because we are performing instantiation from explicitly-specified
1385    // template arguments in a function template class, but there were some
1386    // arguments left unspecified.
1387    if (!TemplateArgs.hasTemplateArgument(T->getDepth(), T->getIndex())) {
1388      TemplateTypeParmTypeLoc NewTL
1389        = TLB.push<TemplateTypeParmTypeLoc>(TL.getType());
1390      NewTL.setNameLoc(TL.getNameLoc());
1391      return TL.getType();
1392    }
1393
1394    TemplateArgument Arg = TemplateArgs(T->getDepth(), T->getIndex());
1395
1396    if (T->isParameterPack()) {
1397      assert(Arg.getKind() == TemplateArgument::Pack &&
1398             "Missing argument pack");
1399
1400      if (getSema().ArgumentPackSubstitutionIndex == -1) {
1401        // We have the template argument pack, but we're not expanding the
1402        // enclosing pack expansion yet. Just save the template argument
1403        // pack for later substitution.
1404        QualType Result
1405          = getSema().Context.getSubstTemplateTypeParmPackType(T, Arg);
1406        SubstTemplateTypeParmPackTypeLoc NewTL
1407          = TLB.push<SubstTemplateTypeParmPackTypeLoc>(Result);
1408        NewTL.setNameLoc(TL.getNameLoc());
1409        return Result;
1410      }
1411
1412      assert(getSema().ArgumentPackSubstitutionIndex < (int)Arg.pack_size());
1413      Arg = Arg.pack_begin()[getSema().ArgumentPackSubstitutionIndex];
1414    }
1415
1416    assert(Arg.getKind() == TemplateArgument::Type &&
1417           "Template argument kind mismatch");
1418
1419    QualType Replacement = Arg.getAsType();
1420
1421    // TODO: only do this uniquing once, at the start of instantiation.
1422    QualType Result
1423      = getSema().Context.getSubstTemplateTypeParmType(T, Replacement);
1424    SubstTemplateTypeParmTypeLoc NewTL
1425      = TLB.push<SubstTemplateTypeParmTypeLoc>(Result);
1426    NewTL.setNameLoc(TL.getNameLoc());
1427    return Result;
1428  }
1429
1430  // The template type parameter comes from an inner template (e.g.,
1431  // the template parameter list of a member template inside the
1432  // template we are instantiating). Create a new template type
1433  // parameter with the template "level" reduced by one.
1434  TemplateTypeParmDecl *NewTTPDecl = 0;
1435  if (TemplateTypeParmDecl *OldTTPDecl = T->getDecl())
1436    NewTTPDecl = cast_or_null<TemplateTypeParmDecl>(
1437                                  TransformDecl(TL.getNameLoc(), OldTTPDecl));
1438
1439  QualType Result
1440    = getSema().Context.getTemplateTypeParmType(T->getDepth()
1441                                                 - TemplateArgs.getNumLevels(),
1442                                                T->getIndex(),
1443                                                T->isParameterPack(),
1444                                                NewTTPDecl);
1445  TemplateTypeParmTypeLoc NewTL = TLB.push<TemplateTypeParmTypeLoc>(Result);
1446  NewTL.setNameLoc(TL.getNameLoc());
1447  return Result;
1448}
1449
1450QualType
1451TemplateInstantiator::TransformSubstTemplateTypeParmPackType(
1452                                                            TypeLocBuilder &TLB,
1453                                         SubstTemplateTypeParmPackTypeLoc TL) {
1454  if (getSema().ArgumentPackSubstitutionIndex == -1) {
1455    // We aren't expanding the parameter pack, so just return ourselves.
1456    SubstTemplateTypeParmPackTypeLoc NewTL
1457      = TLB.push<SubstTemplateTypeParmPackTypeLoc>(TL.getType());
1458    NewTL.setNameLoc(TL.getNameLoc());
1459    return TL.getType();
1460  }
1461
1462  const TemplateArgument &ArgPack = TL.getTypePtr()->getArgumentPack();
1463  unsigned Index = (unsigned)getSema().ArgumentPackSubstitutionIndex;
1464  assert(Index < ArgPack.pack_size() && "Substitution index out-of-range");
1465
1466  QualType Result = ArgPack.pack_begin()[Index].getAsType();
1467  Result = getSema().Context.getSubstTemplateTypeParmType(
1468                                      TL.getTypePtr()->getReplacedParameter(),
1469                                                          Result);
1470  SubstTemplateTypeParmTypeLoc NewTL
1471    = TLB.push<SubstTemplateTypeParmTypeLoc>(Result);
1472  NewTL.setNameLoc(TL.getNameLoc());
1473  return Result;
1474}
1475
1476/// \brief Perform substitution on the type T with a given set of template
1477/// arguments.
1478///
1479/// This routine substitutes the given template arguments into the
1480/// type T and produces the instantiated type.
1481///
1482/// \param T the type into which the template arguments will be
1483/// substituted. If this type is not dependent, it will be returned
1484/// immediately.
1485///
1486/// \param Args the template arguments that will be
1487/// substituted for the top-level template parameters within T.
1488///
1489/// \param Loc the location in the source code where this substitution
1490/// is being performed. It will typically be the location of the
1491/// declarator (if we're instantiating the type of some declaration)
1492/// or the location of the type in the source code (if, e.g., we're
1493/// instantiating the type of a cast expression).
1494///
1495/// \param Entity the name of the entity associated with a declaration
1496/// being instantiated (if any). May be empty to indicate that there
1497/// is no such entity (if, e.g., this is a type that occurs as part of
1498/// a cast expression) or that the entity has no name (e.g., an
1499/// unnamed function parameter).
1500///
1501/// \returns If the instantiation succeeds, the instantiated
1502/// type. Otherwise, produces diagnostics and returns a NULL type.
1503TypeSourceInfo *Sema::SubstType(TypeSourceInfo *T,
1504                                const MultiLevelTemplateArgumentList &Args,
1505                                SourceLocation Loc,
1506                                DeclarationName Entity) {
1507  assert(!ActiveTemplateInstantiations.empty() &&
1508         "Cannot perform an instantiation without some context on the "
1509         "instantiation stack");
1510
1511  if (!T->getType()->isInstantiationDependentType() &&
1512      !T->getType()->isVariablyModifiedType())
1513    return T;
1514
1515  TemplateInstantiator Instantiator(*this, Args, Loc, Entity);
1516  return Instantiator.TransformType(T);
1517}
1518
1519TypeSourceInfo *Sema::SubstType(TypeLoc TL,
1520                                const MultiLevelTemplateArgumentList &Args,
1521                                SourceLocation Loc,
1522                                DeclarationName Entity) {
1523  assert(!ActiveTemplateInstantiations.empty() &&
1524         "Cannot perform an instantiation without some context on the "
1525         "instantiation stack");
1526
1527  if (TL.getType().isNull())
1528    return 0;
1529
1530  if (!TL.getType()->isInstantiationDependentType() &&
1531      !TL.getType()->isVariablyModifiedType()) {
1532    // FIXME: Make a copy of the TypeLoc data here, so that we can
1533    // return a new TypeSourceInfo. Inefficient!
1534    TypeLocBuilder TLB;
1535    TLB.pushFullCopy(TL);
1536    return TLB.getTypeSourceInfo(Context, TL.getType());
1537  }
1538
1539  TemplateInstantiator Instantiator(*this, Args, Loc, Entity);
1540  TypeLocBuilder TLB;
1541  TLB.reserve(TL.getFullDataSize());
1542  QualType Result = Instantiator.TransformType(TLB, TL);
1543  if (Result.isNull())
1544    return 0;
1545
1546  return TLB.getTypeSourceInfo(Context, Result);
1547}
1548
1549/// Deprecated form of the above.
1550QualType Sema::SubstType(QualType T,
1551                         const MultiLevelTemplateArgumentList &TemplateArgs,
1552                         SourceLocation Loc, DeclarationName Entity) {
1553  assert(!ActiveTemplateInstantiations.empty() &&
1554         "Cannot perform an instantiation without some context on the "
1555         "instantiation stack");
1556
1557  // If T is not a dependent type or a variably-modified type, there
1558  // is nothing to do.
1559  if (!T->isInstantiationDependentType() && !T->isVariablyModifiedType())
1560    return T;
1561
1562  TemplateInstantiator Instantiator(*this, TemplateArgs, Loc, Entity);
1563  return Instantiator.TransformType(T);
1564}
1565
1566static bool NeedsInstantiationAsFunctionType(TypeSourceInfo *T) {
1567  if (T->getType()->isInstantiationDependentType() ||
1568      T->getType()->isVariablyModifiedType())
1569    return true;
1570
1571  TypeLoc TL = T->getTypeLoc().IgnoreParens();
1572  if (!TL.getAs<FunctionProtoTypeLoc>())
1573    return false;
1574
1575  FunctionProtoTypeLoc FP = TL.castAs<FunctionProtoTypeLoc>();
1576  for (unsigned I = 0, E = FP.getNumArgs(); I != E; ++I) {
1577    ParmVarDecl *P = FP.getArg(I);
1578
1579    // The parameter's type as written might be dependent even if the
1580    // decayed type was not dependent.
1581    if (TypeSourceInfo *TSInfo = P->getTypeSourceInfo())
1582      if (TSInfo->getType()->isInstantiationDependentType())
1583        return true;
1584
1585    // TODO: currently we always rebuild expressions.  When we
1586    // properly get lazier about this, we should use the same
1587    // logic to avoid rebuilding prototypes here.
1588    if (P->hasDefaultArg())
1589      return true;
1590  }
1591
1592  return false;
1593}
1594
1595/// A form of SubstType intended specifically for instantiating the
1596/// type of a FunctionDecl.  Its purpose is solely to force the
1597/// instantiation of default-argument expressions.
1598TypeSourceInfo *Sema::SubstFunctionDeclType(TypeSourceInfo *T,
1599                                const MultiLevelTemplateArgumentList &Args,
1600                                SourceLocation Loc,
1601                                DeclarationName Entity,
1602                                CXXRecordDecl *ThisContext,
1603                                unsigned ThisTypeQuals) {
1604  assert(!ActiveTemplateInstantiations.empty() &&
1605         "Cannot perform an instantiation without some context on the "
1606         "instantiation stack");
1607
1608  if (!NeedsInstantiationAsFunctionType(T))
1609    return T;
1610
1611  TemplateInstantiator Instantiator(*this, Args, Loc, Entity);
1612
1613  TypeLocBuilder TLB;
1614
1615  TypeLoc TL = T->getTypeLoc();
1616  TLB.reserve(TL.getFullDataSize());
1617
1618  QualType Result;
1619
1620  if (FunctionProtoTypeLoc Proto = TL.getAs<FunctionProtoTypeLoc>()) {
1621    Result = Instantiator.TransformFunctionProtoType(TLB, Proto, ThisContext,
1622                                                     ThisTypeQuals);
1623  } else {
1624    Result = Instantiator.TransformType(TLB, TL);
1625  }
1626  if (Result.isNull())
1627    return 0;
1628
1629  return TLB.getTypeSourceInfo(Context, Result);
1630}
1631
1632ParmVarDecl *Sema::SubstParmVarDecl(ParmVarDecl *OldParm,
1633                            const MultiLevelTemplateArgumentList &TemplateArgs,
1634                                    int indexAdjustment,
1635                                    Optional<unsigned> NumExpansions,
1636                                    bool ExpectParameterPack) {
1637  TypeSourceInfo *OldDI = OldParm->getTypeSourceInfo();
1638  TypeSourceInfo *NewDI = 0;
1639
1640  TypeLoc OldTL = OldDI->getTypeLoc();
1641  if (PackExpansionTypeLoc ExpansionTL = OldTL.getAs<PackExpansionTypeLoc>()) {
1642
1643    // We have a function parameter pack. Substitute into the pattern of the
1644    // expansion.
1645    NewDI = SubstType(ExpansionTL.getPatternLoc(), TemplateArgs,
1646                      OldParm->getLocation(), OldParm->getDeclName());
1647    if (!NewDI)
1648      return 0;
1649
1650    if (NewDI->getType()->containsUnexpandedParameterPack()) {
1651      // We still have unexpanded parameter packs, which means that
1652      // our function parameter is still a function parameter pack.
1653      // Therefore, make its type a pack expansion type.
1654      NewDI = CheckPackExpansion(NewDI, ExpansionTL.getEllipsisLoc(),
1655                                 NumExpansions);
1656    } else if (ExpectParameterPack) {
1657      // We expected to get a parameter pack but didn't (because the type
1658      // itself is not a pack expansion type), so complain. This can occur when
1659      // the substitution goes through an alias template that "loses" the
1660      // pack expansion.
1661      Diag(OldParm->getLocation(),
1662           diag::err_function_parameter_pack_without_parameter_packs)
1663        << NewDI->getType();
1664      return 0;
1665    }
1666  } else {
1667    NewDI = SubstType(OldDI, TemplateArgs, OldParm->getLocation(),
1668                      OldParm->getDeclName());
1669  }
1670
1671  if (!NewDI)
1672    return 0;
1673
1674  if (NewDI->getType()->isVoidType()) {
1675    Diag(OldParm->getLocation(), diag::err_param_with_void_type);
1676    return 0;
1677  }
1678
1679  ParmVarDecl *NewParm = CheckParameter(Context.getTranslationUnitDecl(),
1680                                        OldParm->getInnerLocStart(),
1681                                        OldParm->getLocation(),
1682                                        OldParm->getIdentifier(),
1683                                        NewDI->getType(), NewDI,
1684                                        OldParm->getStorageClass());
1685  if (!NewParm)
1686    return 0;
1687
1688  // Mark the (new) default argument as uninstantiated (if any).
1689  if (OldParm->hasUninstantiatedDefaultArg()) {
1690    Expr *Arg = OldParm->getUninstantiatedDefaultArg();
1691    NewParm->setUninstantiatedDefaultArg(Arg);
1692  } else if (OldParm->hasUnparsedDefaultArg()) {
1693    NewParm->setUnparsedDefaultArg();
1694    UnparsedDefaultArgInstantiations[OldParm].push_back(NewParm);
1695  } else if (Expr *Arg = OldParm->getDefaultArg())
1696    // FIXME: if we non-lazily instantiated non-dependent default args for
1697    // non-dependent parameter types we could remove a bunch of duplicate
1698    // conversion warnings for such arguments.
1699    NewParm->setUninstantiatedDefaultArg(Arg);
1700
1701  NewParm->setHasInheritedDefaultArg(OldParm->hasInheritedDefaultArg());
1702
1703  if (OldParm->isParameterPack() && !NewParm->isParameterPack()) {
1704    // Add the new parameter to the instantiated parameter pack.
1705    CurrentInstantiationScope->InstantiatedLocalPackArg(OldParm, NewParm);
1706  } else {
1707    // Introduce an Old -> New mapping
1708    CurrentInstantiationScope->InstantiatedLocal(OldParm, NewParm);
1709  }
1710
1711  // FIXME: OldParm may come from a FunctionProtoType, in which case CurContext
1712  // can be anything, is this right ?
1713  NewParm->setDeclContext(CurContext);
1714
1715  NewParm->setScopeInfo(OldParm->getFunctionScopeDepth(),
1716                        OldParm->getFunctionScopeIndex() + indexAdjustment);
1717
1718  InstantiateAttrs(TemplateArgs, OldParm, NewParm);
1719
1720  return NewParm;
1721}
1722
1723/// \brief Substitute the given template arguments into the given set of
1724/// parameters, producing the set of parameter types that would be generated
1725/// from such a substitution.
1726bool Sema::SubstParmTypes(SourceLocation Loc,
1727                          ParmVarDecl **Params, unsigned NumParams,
1728                          const MultiLevelTemplateArgumentList &TemplateArgs,
1729                          SmallVectorImpl<QualType> &ParamTypes,
1730                          SmallVectorImpl<ParmVarDecl *> *OutParams) {
1731  assert(!ActiveTemplateInstantiations.empty() &&
1732         "Cannot perform an instantiation without some context on the "
1733         "instantiation stack");
1734
1735  TemplateInstantiator Instantiator(*this, TemplateArgs, Loc,
1736                                    DeclarationName());
1737  return Instantiator.TransformFunctionTypeParams(Loc, Params, NumParams, 0,
1738                                                  ParamTypes, OutParams);
1739}
1740
1741/// \brief Perform substitution on the base class specifiers of the
1742/// given class template specialization.
1743///
1744/// Produces a diagnostic and returns true on error, returns false and
1745/// attaches the instantiated base classes to the class template
1746/// specialization if successful.
1747bool
1748Sema::SubstBaseSpecifiers(CXXRecordDecl *Instantiation,
1749                          CXXRecordDecl *Pattern,
1750                          const MultiLevelTemplateArgumentList &TemplateArgs) {
1751  bool Invalid = false;
1752  SmallVector<CXXBaseSpecifier*, 4> InstantiatedBases;
1753  for (ClassTemplateSpecializationDecl::base_class_iterator
1754         Base = Pattern->bases_begin(), BaseEnd = Pattern->bases_end();
1755       Base != BaseEnd; ++Base) {
1756    if (!Base->getType()->isDependentType()) {
1757      if (const CXXRecordDecl *RD = Base->getType()->getAsCXXRecordDecl()) {
1758        if (RD->isInvalidDecl())
1759          Instantiation->setInvalidDecl();
1760      }
1761      InstantiatedBases.push_back(new (Context) CXXBaseSpecifier(*Base));
1762      continue;
1763    }
1764
1765    SourceLocation EllipsisLoc;
1766    TypeSourceInfo *BaseTypeLoc;
1767    if (Base->isPackExpansion()) {
1768      // This is a pack expansion. See whether we should expand it now, or
1769      // wait until later.
1770      SmallVector<UnexpandedParameterPack, 2> Unexpanded;
1771      collectUnexpandedParameterPacks(Base->getTypeSourceInfo()->getTypeLoc(),
1772                                      Unexpanded);
1773      bool ShouldExpand = false;
1774      bool RetainExpansion = false;
1775      Optional<unsigned> NumExpansions;
1776      if (CheckParameterPacksForExpansion(Base->getEllipsisLoc(),
1777                                          Base->getSourceRange(),
1778                                          Unexpanded,
1779                                          TemplateArgs, ShouldExpand,
1780                                          RetainExpansion,
1781                                          NumExpansions)) {
1782        Invalid = true;
1783        continue;
1784      }
1785
1786      // If we should expand this pack expansion now, do so.
1787      if (ShouldExpand) {
1788        for (unsigned I = 0; I != *NumExpansions; ++I) {
1789            Sema::ArgumentPackSubstitutionIndexRAII SubstIndex(*this, I);
1790
1791          TypeSourceInfo *BaseTypeLoc = SubstType(Base->getTypeSourceInfo(),
1792                                                  TemplateArgs,
1793                                              Base->getSourceRange().getBegin(),
1794                                                  DeclarationName());
1795          if (!BaseTypeLoc) {
1796            Invalid = true;
1797            continue;
1798          }
1799
1800          if (CXXBaseSpecifier *InstantiatedBase
1801                = CheckBaseSpecifier(Instantiation,
1802                                     Base->getSourceRange(),
1803                                     Base->isVirtual(),
1804                                     Base->getAccessSpecifierAsWritten(),
1805                                     BaseTypeLoc,
1806                                     SourceLocation()))
1807            InstantiatedBases.push_back(InstantiatedBase);
1808          else
1809            Invalid = true;
1810        }
1811
1812        continue;
1813      }
1814
1815      // The resulting base specifier will (still) be a pack expansion.
1816      EllipsisLoc = Base->getEllipsisLoc();
1817      Sema::ArgumentPackSubstitutionIndexRAII SubstIndex(*this, -1);
1818      BaseTypeLoc = SubstType(Base->getTypeSourceInfo(),
1819                              TemplateArgs,
1820                              Base->getSourceRange().getBegin(),
1821                              DeclarationName());
1822    } else {
1823      BaseTypeLoc = SubstType(Base->getTypeSourceInfo(),
1824                              TemplateArgs,
1825                              Base->getSourceRange().getBegin(),
1826                              DeclarationName());
1827    }
1828
1829    if (!BaseTypeLoc) {
1830      Invalid = true;
1831      continue;
1832    }
1833
1834    if (CXXBaseSpecifier *InstantiatedBase
1835          = CheckBaseSpecifier(Instantiation,
1836                               Base->getSourceRange(),
1837                               Base->isVirtual(),
1838                               Base->getAccessSpecifierAsWritten(),
1839                               BaseTypeLoc,
1840                               EllipsisLoc))
1841      InstantiatedBases.push_back(InstantiatedBase);
1842    else
1843      Invalid = true;
1844  }
1845
1846  if (!Invalid &&
1847      AttachBaseSpecifiers(Instantiation, InstantiatedBases.data(),
1848                           InstantiatedBases.size()))
1849    Invalid = true;
1850
1851  return Invalid;
1852}
1853
1854// Defined via #include from SemaTemplateInstantiateDecl.cpp
1855namespace clang {
1856  namespace sema {
1857    Attr *instantiateTemplateAttribute(const Attr *At, ASTContext &C, Sema &S,
1858                            const MultiLevelTemplateArgumentList &TemplateArgs);
1859  }
1860}
1861
1862/// Determine whether we would be unable to instantiate this template (because
1863/// it either has no definition, or is in the process of being instantiated).
1864static bool DiagnoseUninstantiableTemplate(Sema &S,
1865                                           SourceLocation PointOfInstantiation,
1866                                           TagDecl *Instantiation,
1867                                           bool InstantiatedFromMember,
1868                                           TagDecl *Pattern,
1869                                           TagDecl *PatternDef,
1870                                           TemplateSpecializationKind TSK,
1871                                           bool Complain = true) {
1872  if (PatternDef && !PatternDef->isBeingDefined())
1873    return false;
1874
1875  if (!Complain || (PatternDef && PatternDef->isInvalidDecl())) {
1876    // Say nothing
1877  } else if (PatternDef) {
1878    assert(PatternDef->isBeingDefined());
1879    S.Diag(PointOfInstantiation,
1880           diag::err_template_instantiate_within_definition)
1881      << (TSK != TSK_ImplicitInstantiation)
1882      << S.Context.getTypeDeclType(Instantiation);
1883    // Not much point in noting the template declaration here, since
1884    // we're lexically inside it.
1885    Instantiation->setInvalidDecl();
1886  } else if (InstantiatedFromMember) {
1887    S.Diag(PointOfInstantiation,
1888           diag::err_implicit_instantiate_member_undefined)
1889      << S.Context.getTypeDeclType(Instantiation);
1890    S.Diag(Pattern->getLocation(), diag::note_member_of_template_here);
1891  } else {
1892    S.Diag(PointOfInstantiation, diag::err_template_instantiate_undefined)
1893      << (TSK != TSK_ImplicitInstantiation)
1894      << S.Context.getTypeDeclType(Instantiation);
1895    S.Diag(Pattern->getLocation(), diag::note_template_decl_here);
1896  }
1897
1898  // In general, Instantiation isn't marked invalid to get more than one
1899  // error for multiple undefined instantiations. But the code that does
1900  // explicit declaration -> explicit definition conversion can't handle
1901  // invalid declarations, so mark as invalid in that case.
1902  if (TSK == TSK_ExplicitInstantiationDeclaration)
1903    Instantiation->setInvalidDecl();
1904  return true;
1905}
1906
1907/// \brief Instantiate the definition of a class from a given pattern.
1908///
1909/// \param PointOfInstantiation The point of instantiation within the
1910/// source code.
1911///
1912/// \param Instantiation is the declaration whose definition is being
1913/// instantiated. This will be either a class template specialization
1914/// or a member class of a class template specialization.
1915///
1916/// \param Pattern is the pattern from which the instantiation
1917/// occurs. This will be either the declaration of a class template or
1918/// the declaration of a member class of a class template.
1919///
1920/// \param TemplateArgs The template arguments to be substituted into
1921/// the pattern.
1922///
1923/// \param TSK the kind of implicit or explicit instantiation to perform.
1924///
1925/// \param Complain whether to complain if the class cannot be instantiated due
1926/// to the lack of a definition.
1927///
1928/// \returns true if an error occurred, false otherwise.
1929bool
1930Sema::InstantiateClass(SourceLocation PointOfInstantiation,
1931                       CXXRecordDecl *Instantiation, CXXRecordDecl *Pattern,
1932                       const MultiLevelTemplateArgumentList &TemplateArgs,
1933                       TemplateSpecializationKind TSK,
1934                       bool Complain) {
1935  CXXRecordDecl *PatternDef
1936    = cast_or_null<CXXRecordDecl>(Pattern->getDefinition());
1937  if (DiagnoseUninstantiableTemplate(*this, PointOfInstantiation, Instantiation,
1938                                Instantiation->getInstantiatedFromMemberClass(),
1939                                     Pattern, PatternDef, TSK, Complain))
1940    return true;
1941  Pattern = PatternDef;
1942
1943  // \brief Record the point of instantiation.
1944  if (MemberSpecializationInfo *MSInfo
1945        = Instantiation->getMemberSpecializationInfo()) {
1946    MSInfo->setTemplateSpecializationKind(TSK);
1947    MSInfo->setPointOfInstantiation(PointOfInstantiation);
1948  } else if (ClassTemplateSpecializationDecl *Spec
1949        = dyn_cast<ClassTemplateSpecializationDecl>(Instantiation)) {
1950    Spec->setTemplateSpecializationKind(TSK);
1951    Spec->setPointOfInstantiation(PointOfInstantiation);
1952  }
1953
1954  InstantiatingTemplate Inst(*this, PointOfInstantiation, Instantiation);
1955  if (Inst)
1956    return true;
1957
1958  // Enter the scope of this instantiation. We don't use
1959  // PushDeclContext because we don't have a scope.
1960  ContextRAII SavedContext(*this, Instantiation);
1961  EnterExpressionEvaluationContext EvalContext(*this,
1962                                               Sema::PotentiallyEvaluated);
1963
1964  // If this is an instantiation of a local class, merge this local
1965  // instantiation scope with the enclosing scope. Otherwise, every
1966  // instantiation of a class has its own local instantiation scope.
1967  bool MergeWithParentScope = !Instantiation->isDefinedOutsideFunctionOrMethod();
1968  LocalInstantiationScope Scope(*this, MergeWithParentScope);
1969
1970  // Pull attributes from the pattern onto the instantiation.
1971  InstantiateAttrs(TemplateArgs, Pattern, Instantiation);
1972
1973  // Start the definition of this instantiation.
1974  Instantiation->startDefinition();
1975
1976  Instantiation->setTagKind(Pattern->getTagKind());
1977
1978  // Do substitution on the base class specifiers.
1979  if (SubstBaseSpecifiers(Instantiation, Pattern, TemplateArgs))
1980    Instantiation->setInvalidDecl();
1981
1982  TemplateDeclInstantiator Instantiator(*this, Instantiation, TemplateArgs);
1983  SmallVector<Decl*, 4> Fields;
1984  SmallVector<std::pair<FieldDecl*, FieldDecl*>, 4>
1985    FieldsWithMemberInitializers;
1986  // Delay instantiation of late parsed attributes.
1987  LateInstantiatedAttrVec LateAttrs;
1988  Instantiator.enableLateAttributeInstantiation(&LateAttrs);
1989
1990  for (RecordDecl::decl_iterator Member = Pattern->decls_begin(),
1991         MemberEnd = Pattern->decls_end();
1992       Member != MemberEnd; ++Member) {
1993    // Don't instantiate members not belonging in this semantic context.
1994    // e.g. for:
1995    // @code
1996    //    template <int i> class A {
1997    //      class B *g;
1998    //    };
1999    // @endcode
2000    // 'class B' has the template as lexical context but semantically it is
2001    // introduced in namespace scope.
2002    if ((*Member)->getDeclContext() != Pattern)
2003      continue;
2004
2005    if ((*Member)->isInvalidDecl()) {
2006      Instantiation->setInvalidDecl();
2007      continue;
2008    }
2009
2010    Decl *NewMember = Instantiator.Visit(*Member);
2011    if (NewMember) {
2012      if (FieldDecl *Field = dyn_cast<FieldDecl>(NewMember)) {
2013        Fields.push_back(Field);
2014        FieldDecl *OldField = cast<FieldDecl>(*Member);
2015        if (OldField->getInClassInitializer())
2016          FieldsWithMemberInitializers.push_back(std::make_pair(OldField,
2017                                                                Field));
2018      } else if (EnumDecl *Enum = dyn_cast<EnumDecl>(NewMember)) {
2019        // C++11 [temp.inst]p1: The implicit instantiation of a class template
2020        // specialization causes the implicit instantiation of the definitions
2021        // of unscoped member enumerations.
2022        // Record a point of instantiation for this implicit instantiation.
2023        if (TSK == TSK_ImplicitInstantiation && !Enum->isScoped() &&
2024            Enum->isCompleteDefinition()) {
2025          MemberSpecializationInfo *MSInfo =Enum->getMemberSpecializationInfo();
2026          assert(MSInfo && "no spec info for member enum specialization");
2027          MSInfo->setTemplateSpecializationKind(TSK_ImplicitInstantiation);
2028          MSInfo->setPointOfInstantiation(PointOfInstantiation);
2029        }
2030      } else if (StaticAssertDecl *SA = dyn_cast<StaticAssertDecl>(NewMember)) {
2031        if (SA->isFailed()) {
2032          // A static_assert failed. Bail out; instantiating this
2033          // class is probably not meaningful.
2034          Instantiation->setInvalidDecl();
2035          break;
2036        }
2037      }
2038
2039      if (NewMember->isInvalidDecl())
2040        Instantiation->setInvalidDecl();
2041    } else {
2042      // FIXME: Eventually, a NULL return will mean that one of the
2043      // instantiations was a semantic disaster, and we'll want to mark the
2044      // declaration invalid.
2045      // For now, we expect to skip some members that we can't yet handle.
2046    }
2047  }
2048
2049  // Finish checking fields.
2050  ActOnFields(0, Instantiation->getLocation(), Instantiation, Fields,
2051              SourceLocation(), SourceLocation(), 0);
2052  CheckCompletedCXXClass(Instantiation);
2053
2054  // Attach any in-class member initializers now the class is complete.
2055  // FIXME: We are supposed to defer instantiating these until they are needed.
2056  if (!FieldsWithMemberInitializers.empty()) {
2057    // C++11 [expr.prim.general]p4:
2058    //   Otherwise, if a member-declarator declares a non-static data member
2059    //  (9.2) of a class X, the expression this is a prvalue of type "pointer
2060    //  to X" within the optional brace-or-equal-initializer. It shall not
2061    //  appear elsewhere in the member-declarator.
2062    CXXThisScopeRAII ThisScope(*this, Instantiation, (unsigned)0);
2063
2064    for (unsigned I = 0, N = FieldsWithMemberInitializers.size(); I != N; ++I) {
2065      FieldDecl *OldField = FieldsWithMemberInitializers[I].first;
2066      FieldDecl *NewField = FieldsWithMemberInitializers[I].second;
2067      Expr *OldInit = OldField->getInClassInitializer();
2068
2069      ExprResult NewInit = SubstInitializer(OldInit, TemplateArgs,
2070                                            /*CXXDirectInit=*/false);
2071      if (NewInit.isInvalid())
2072        NewField->setInvalidDecl();
2073      else {
2074        Expr *Init = NewInit.take();
2075        assert(Init && "no-argument initializer in class");
2076        assert(!isa<ParenListExpr>(Init) && "call-style init in class");
2077        ActOnCXXInClassMemberInitializer(NewField, Init->getLocStart(), Init);
2078      }
2079    }
2080  }
2081  // Instantiate late parsed attributes, and attach them to their decls.
2082  // See Sema::InstantiateAttrs
2083  for (LateInstantiatedAttrVec::iterator I = LateAttrs.begin(),
2084       E = LateAttrs.end(); I != E; ++I) {
2085    assert(CurrentInstantiationScope == Instantiator.getStartingScope());
2086    CurrentInstantiationScope = I->Scope;
2087
2088    // Allow 'this' within late-parsed attributes.
2089    NamedDecl *ND = dyn_cast<NamedDecl>(I->NewDecl);
2090    CXXRecordDecl *ThisContext =
2091        dyn_cast_or_null<CXXRecordDecl>(ND->getDeclContext());
2092    CXXThisScopeRAII ThisScope(*this, ThisContext, /*TypeQuals*/0,
2093                               ND && ND->isCXXInstanceMember());
2094
2095    Attr *NewAttr =
2096      instantiateTemplateAttribute(I->TmplAttr, Context, *this, TemplateArgs);
2097    I->NewDecl->addAttr(NewAttr);
2098    LocalInstantiationScope::deleteScopes(I->Scope,
2099                                          Instantiator.getStartingScope());
2100  }
2101  Instantiator.disableLateAttributeInstantiation();
2102  LateAttrs.clear();
2103
2104  ActOnFinishDelayedMemberInitializers(Instantiation);
2105
2106  if (TSK == TSK_ImplicitInstantiation) {
2107    Instantiation->setLocation(Pattern->getLocation());
2108    Instantiation->setLocStart(Pattern->getInnerLocStart());
2109    Instantiation->setRBraceLoc(Pattern->getRBraceLoc());
2110  }
2111
2112  if (!Instantiation->isInvalidDecl()) {
2113    // Perform any dependent diagnostics from the pattern.
2114    PerformDependentDiagnostics(Pattern, TemplateArgs);
2115
2116    // Instantiate any out-of-line class template partial
2117    // specializations now.
2118    for (TemplateDeclInstantiator::delayed_partial_spec_iterator
2119              P = Instantiator.delayed_partial_spec_begin(),
2120           PEnd = Instantiator.delayed_partial_spec_end();
2121         P != PEnd; ++P) {
2122      if (!Instantiator.InstantiateClassTemplatePartialSpecialization(
2123                                                                P->first,
2124                                                                P->second)) {
2125        Instantiation->setInvalidDecl();
2126        break;
2127      }
2128    }
2129  }
2130
2131  // Exit the scope of this instantiation.
2132  SavedContext.pop();
2133
2134  if (!Instantiation->isInvalidDecl()) {
2135    Consumer.HandleTagDeclDefinition(Instantiation);
2136
2137    // Always emit the vtable for an explicit instantiation definition
2138    // of a polymorphic class template specialization.
2139    if (TSK == TSK_ExplicitInstantiationDefinition)
2140      MarkVTableUsed(PointOfInstantiation, Instantiation, true);
2141  }
2142
2143  return Instantiation->isInvalidDecl();
2144}
2145
2146/// \brief Instantiate the definition of an enum from a given pattern.
2147///
2148/// \param PointOfInstantiation The point of instantiation within the
2149///        source code.
2150/// \param Instantiation is the declaration whose definition is being
2151///        instantiated. This will be a member enumeration of a class
2152///        temploid specialization, or a local enumeration within a
2153///        function temploid specialization.
2154/// \param Pattern The templated declaration from which the instantiation
2155///        occurs.
2156/// \param TemplateArgs The template arguments to be substituted into
2157///        the pattern.
2158/// \param TSK The kind of implicit or explicit instantiation to perform.
2159///
2160/// \return \c true if an error occurred, \c false otherwise.
2161bool Sema::InstantiateEnum(SourceLocation PointOfInstantiation,
2162                           EnumDecl *Instantiation, EnumDecl *Pattern,
2163                           const MultiLevelTemplateArgumentList &TemplateArgs,
2164                           TemplateSpecializationKind TSK) {
2165  EnumDecl *PatternDef = Pattern->getDefinition();
2166  if (DiagnoseUninstantiableTemplate(*this, PointOfInstantiation, Instantiation,
2167                                 Instantiation->getInstantiatedFromMemberEnum(),
2168                                     Pattern, PatternDef, TSK,/*Complain*/true))
2169    return true;
2170  Pattern = PatternDef;
2171
2172  // Record the point of instantiation.
2173  if (MemberSpecializationInfo *MSInfo
2174        = Instantiation->getMemberSpecializationInfo()) {
2175    MSInfo->setTemplateSpecializationKind(TSK);
2176    MSInfo->setPointOfInstantiation(PointOfInstantiation);
2177  }
2178
2179  InstantiatingTemplate Inst(*this, PointOfInstantiation, Instantiation);
2180  if (Inst)
2181    return true;
2182
2183  // Enter the scope of this instantiation. We don't use
2184  // PushDeclContext because we don't have a scope.
2185  ContextRAII SavedContext(*this, Instantiation);
2186  EnterExpressionEvaluationContext EvalContext(*this,
2187                                               Sema::PotentiallyEvaluated);
2188
2189  LocalInstantiationScope Scope(*this, /*MergeWithParentScope*/true);
2190
2191  // Pull attributes from the pattern onto the instantiation.
2192  InstantiateAttrs(TemplateArgs, Pattern, Instantiation);
2193
2194  TemplateDeclInstantiator Instantiator(*this, Instantiation, TemplateArgs);
2195  Instantiator.InstantiateEnumDefinition(Instantiation, Pattern);
2196
2197  // Exit the scope of this instantiation.
2198  SavedContext.pop();
2199
2200  return Instantiation->isInvalidDecl();
2201}
2202
2203namespace {
2204  /// \brief A partial specialization whose template arguments have matched
2205  /// a given template-id.
2206  struct PartialSpecMatchResult {
2207    ClassTemplatePartialSpecializationDecl *Partial;
2208    TemplateArgumentList *Args;
2209  };
2210}
2211
2212bool
2213Sema::InstantiateClassTemplateSpecialization(
2214                           SourceLocation PointOfInstantiation,
2215                           ClassTemplateSpecializationDecl *ClassTemplateSpec,
2216                           TemplateSpecializationKind TSK,
2217                           bool Complain) {
2218  // Perform the actual instantiation on the canonical declaration.
2219  ClassTemplateSpec = cast<ClassTemplateSpecializationDecl>(
2220                                         ClassTemplateSpec->getCanonicalDecl());
2221
2222  // Check whether we have already instantiated or specialized this class
2223  // template specialization.
2224  if (ClassTemplateSpec->getSpecializationKind() != TSK_Undeclared) {
2225    if (ClassTemplateSpec->getSpecializationKind() ==
2226          TSK_ExplicitInstantiationDeclaration &&
2227        TSK == TSK_ExplicitInstantiationDefinition) {
2228      // An explicit instantiation definition follows an explicit instantiation
2229      // declaration (C++0x [temp.explicit]p10); go ahead and perform the
2230      // explicit instantiation.
2231      ClassTemplateSpec->setSpecializationKind(TSK);
2232
2233      // If this is an explicit instantiation definition, mark the
2234      // vtable as used.
2235      if (TSK == TSK_ExplicitInstantiationDefinition &&
2236          !ClassTemplateSpec->isInvalidDecl())
2237        MarkVTableUsed(PointOfInstantiation, ClassTemplateSpec, true);
2238
2239      return false;
2240    }
2241
2242    // We can only instantiate something that hasn't already been
2243    // instantiated or specialized. Fail without any diagnostics: our
2244    // caller will provide an error message.
2245    return true;
2246  }
2247
2248  if (ClassTemplateSpec->isInvalidDecl())
2249    return true;
2250
2251  ClassTemplateDecl *Template = ClassTemplateSpec->getSpecializedTemplate();
2252  CXXRecordDecl *Pattern = 0;
2253
2254  // C++ [temp.class.spec.match]p1:
2255  //   When a class template is used in a context that requires an
2256  //   instantiation of the class, it is necessary to determine
2257  //   whether the instantiation is to be generated using the primary
2258  //   template or one of the partial specializations. This is done by
2259  //   matching the template arguments of the class template
2260  //   specialization with the template argument lists of the partial
2261  //   specializations.
2262  typedef PartialSpecMatchResult MatchResult;
2263  SmallVector<MatchResult, 4> Matched;
2264  SmallVector<ClassTemplatePartialSpecializationDecl *, 4> PartialSpecs;
2265  Template->getPartialSpecializations(PartialSpecs);
2266  for (unsigned I = 0, N = PartialSpecs.size(); I != N; ++I) {
2267    ClassTemplatePartialSpecializationDecl *Partial = PartialSpecs[I];
2268    TemplateDeductionInfo Info(PointOfInstantiation);
2269    if (TemplateDeductionResult Result
2270          = DeduceTemplateArguments(Partial,
2271                                    ClassTemplateSpec->getTemplateArgs(),
2272                                    Info)) {
2273      // FIXME: Store the failed-deduction information for use in
2274      // diagnostics, later.
2275      (void)Result;
2276    } else {
2277      Matched.push_back(PartialSpecMatchResult());
2278      Matched.back().Partial = Partial;
2279      Matched.back().Args = Info.take();
2280    }
2281  }
2282
2283  // If we're dealing with a member template where the template parameters
2284  // have been instantiated, this provides the original template parameters
2285  // from which the member template's parameters were instantiated.
2286  SmallVector<const NamedDecl *, 4> InstantiatedTemplateParameters;
2287
2288  if (Matched.size() >= 1) {
2289    SmallVector<MatchResult, 4>::iterator Best = Matched.begin();
2290    if (Matched.size() == 1) {
2291      //   -- If exactly one matching specialization is found, the
2292      //      instantiation is generated from that specialization.
2293      // We don't need to do anything for this.
2294    } else {
2295      //   -- If more than one matching specialization is found, the
2296      //      partial order rules (14.5.4.2) are used to determine
2297      //      whether one of the specializations is more specialized
2298      //      than the others. If none of the specializations is more
2299      //      specialized than all of the other matching
2300      //      specializations, then the use of the class template is
2301      //      ambiguous and the program is ill-formed.
2302      for (SmallVector<MatchResult, 4>::iterator P = Best + 1,
2303                                                    PEnd = Matched.end();
2304           P != PEnd; ++P) {
2305        if (getMoreSpecializedPartialSpecialization(P->Partial, Best->Partial,
2306                                                    PointOfInstantiation)
2307              == P->Partial)
2308          Best = P;
2309      }
2310
2311      // Determine if the best partial specialization is more specialized than
2312      // the others.
2313      bool Ambiguous = false;
2314      for (SmallVector<MatchResult, 4>::iterator P = Matched.begin(),
2315                                                    PEnd = Matched.end();
2316           P != PEnd; ++P) {
2317        if (P != Best &&
2318            getMoreSpecializedPartialSpecialization(P->Partial, Best->Partial,
2319                                                    PointOfInstantiation)
2320              != Best->Partial) {
2321          Ambiguous = true;
2322          break;
2323        }
2324      }
2325
2326      if (Ambiguous) {
2327        // Partial ordering did not produce a clear winner. Complain.
2328        ClassTemplateSpec->setInvalidDecl();
2329        Diag(PointOfInstantiation, diag::err_partial_spec_ordering_ambiguous)
2330          << ClassTemplateSpec;
2331
2332        // Print the matching partial specializations.
2333        for (SmallVector<MatchResult, 4>::iterator P = Matched.begin(),
2334                                                      PEnd = Matched.end();
2335             P != PEnd; ++P)
2336          Diag(P->Partial->getLocation(), diag::note_partial_spec_match)
2337            << getTemplateArgumentBindingsText(
2338                                            P->Partial->getTemplateParameters(),
2339                                               *P->Args);
2340
2341        return true;
2342      }
2343    }
2344
2345    // Instantiate using the best class template partial specialization.
2346    ClassTemplatePartialSpecializationDecl *OrigPartialSpec = Best->Partial;
2347    while (OrigPartialSpec->getInstantiatedFromMember()) {
2348      // If we've found an explicit specialization of this class template,
2349      // stop here and use that as the pattern.
2350      if (OrigPartialSpec->isMemberSpecialization())
2351        break;
2352
2353      OrigPartialSpec = OrigPartialSpec->getInstantiatedFromMember();
2354    }
2355
2356    Pattern = OrigPartialSpec;
2357    ClassTemplateSpec->setInstantiationOf(Best->Partial, Best->Args);
2358  } else {
2359    //   -- If no matches are found, the instantiation is generated
2360    //      from the primary template.
2361    ClassTemplateDecl *OrigTemplate = Template;
2362    while (OrigTemplate->getInstantiatedFromMemberTemplate()) {
2363      // If we've found an explicit specialization of this class template,
2364      // stop here and use that as the pattern.
2365      if (OrigTemplate->isMemberSpecialization())
2366        break;
2367
2368      OrigTemplate = OrigTemplate->getInstantiatedFromMemberTemplate();
2369    }
2370
2371    Pattern = OrigTemplate->getTemplatedDecl();
2372  }
2373
2374  bool Result = InstantiateClass(PointOfInstantiation, ClassTemplateSpec,
2375                                 Pattern,
2376                                getTemplateInstantiationArgs(ClassTemplateSpec),
2377                                 TSK,
2378                                 Complain);
2379
2380  return Result;
2381}
2382
2383/// \brief Instantiates the definitions of all of the member
2384/// of the given class, which is an instantiation of a class template
2385/// or a member class of a template.
2386void
2387Sema::InstantiateClassMembers(SourceLocation PointOfInstantiation,
2388                              CXXRecordDecl *Instantiation,
2389                        const MultiLevelTemplateArgumentList &TemplateArgs,
2390                              TemplateSpecializationKind TSK) {
2391  for (DeclContext::decl_iterator D = Instantiation->decls_begin(),
2392                               DEnd = Instantiation->decls_end();
2393       D != DEnd; ++D) {
2394    bool SuppressNew = false;
2395    if (FunctionDecl *Function = dyn_cast<FunctionDecl>(*D)) {
2396      if (FunctionDecl *Pattern
2397            = Function->getInstantiatedFromMemberFunction()) {
2398        MemberSpecializationInfo *MSInfo
2399          = Function->getMemberSpecializationInfo();
2400        assert(MSInfo && "No member specialization information?");
2401        if (MSInfo->getTemplateSpecializationKind()
2402                                                 == TSK_ExplicitSpecialization)
2403          continue;
2404
2405        if (CheckSpecializationInstantiationRedecl(PointOfInstantiation, TSK,
2406                                                   Function,
2407                                        MSInfo->getTemplateSpecializationKind(),
2408                                              MSInfo->getPointOfInstantiation(),
2409                                                   SuppressNew) ||
2410            SuppressNew)
2411          continue;
2412
2413        if (Function->isDefined())
2414          continue;
2415
2416        if (TSK == TSK_ExplicitInstantiationDefinition) {
2417          // C++0x [temp.explicit]p8:
2418          //   An explicit instantiation definition that names a class template
2419          //   specialization explicitly instantiates the class template
2420          //   specialization and is only an explicit instantiation definition
2421          //   of members whose definition is visible at the point of
2422          //   instantiation.
2423          if (!Pattern->isDefined())
2424            continue;
2425
2426          Function->setTemplateSpecializationKind(TSK, PointOfInstantiation);
2427
2428          InstantiateFunctionDefinition(PointOfInstantiation, Function);
2429        } else {
2430          Function->setTemplateSpecializationKind(TSK, PointOfInstantiation);
2431        }
2432      }
2433    } else if (VarDecl *Var = dyn_cast<VarDecl>(*D)) {
2434      if (Var->isStaticDataMember()) {
2435        MemberSpecializationInfo *MSInfo = Var->getMemberSpecializationInfo();
2436        assert(MSInfo && "No member specialization information?");
2437        if (MSInfo->getTemplateSpecializationKind()
2438                                                 == TSK_ExplicitSpecialization)
2439          continue;
2440
2441        if (CheckSpecializationInstantiationRedecl(PointOfInstantiation, TSK,
2442                                                   Var,
2443                                        MSInfo->getTemplateSpecializationKind(),
2444                                              MSInfo->getPointOfInstantiation(),
2445                                                   SuppressNew) ||
2446            SuppressNew)
2447          continue;
2448
2449        if (TSK == TSK_ExplicitInstantiationDefinition) {
2450          // C++0x [temp.explicit]p8:
2451          //   An explicit instantiation definition that names a class template
2452          //   specialization explicitly instantiates the class template
2453          //   specialization and is only an explicit instantiation definition
2454          //   of members whose definition is visible at the point of
2455          //   instantiation.
2456          if (!Var->getInstantiatedFromStaticDataMember()
2457                                                     ->getOutOfLineDefinition())
2458            continue;
2459
2460          Var->setTemplateSpecializationKind(TSK, PointOfInstantiation);
2461          InstantiateStaticDataMemberDefinition(PointOfInstantiation, Var);
2462        } else {
2463          Var->setTemplateSpecializationKind(TSK, PointOfInstantiation);
2464        }
2465      }
2466    } else if (CXXRecordDecl *Record = dyn_cast<CXXRecordDecl>(*D)) {
2467      // Always skip the injected-class-name, along with any
2468      // redeclarations of nested classes, since both would cause us
2469      // to try to instantiate the members of a class twice.
2470      if (Record->isInjectedClassName() || Record->getPreviousDecl())
2471        continue;
2472
2473      MemberSpecializationInfo *MSInfo = Record->getMemberSpecializationInfo();
2474      assert(MSInfo && "No member specialization information?");
2475
2476      if (MSInfo->getTemplateSpecializationKind()
2477                                                == TSK_ExplicitSpecialization)
2478        continue;
2479
2480      if (CheckSpecializationInstantiationRedecl(PointOfInstantiation, TSK,
2481                                                 Record,
2482                                        MSInfo->getTemplateSpecializationKind(),
2483                                              MSInfo->getPointOfInstantiation(),
2484                                                 SuppressNew) ||
2485          SuppressNew)
2486        continue;
2487
2488      CXXRecordDecl *Pattern = Record->getInstantiatedFromMemberClass();
2489      assert(Pattern && "Missing instantiated-from-template information");
2490
2491      if (!Record->getDefinition()) {
2492        if (!Pattern->getDefinition()) {
2493          // C++0x [temp.explicit]p8:
2494          //   An explicit instantiation definition that names a class template
2495          //   specialization explicitly instantiates the class template
2496          //   specialization and is only an explicit instantiation definition
2497          //   of members whose definition is visible at the point of
2498          //   instantiation.
2499          if (TSK == TSK_ExplicitInstantiationDeclaration) {
2500            MSInfo->setTemplateSpecializationKind(TSK);
2501            MSInfo->setPointOfInstantiation(PointOfInstantiation);
2502          }
2503
2504          continue;
2505        }
2506
2507        InstantiateClass(PointOfInstantiation, Record, Pattern,
2508                         TemplateArgs,
2509                         TSK);
2510      } else {
2511        if (TSK == TSK_ExplicitInstantiationDefinition &&
2512            Record->getTemplateSpecializationKind() ==
2513                TSK_ExplicitInstantiationDeclaration) {
2514          Record->setTemplateSpecializationKind(TSK);
2515          MarkVTableUsed(PointOfInstantiation, Record, true);
2516        }
2517      }
2518
2519      Pattern = cast_or_null<CXXRecordDecl>(Record->getDefinition());
2520      if (Pattern)
2521        InstantiateClassMembers(PointOfInstantiation, Pattern, TemplateArgs,
2522                                TSK);
2523    } else if (EnumDecl *Enum = dyn_cast<EnumDecl>(*D)) {
2524      MemberSpecializationInfo *MSInfo = Enum->getMemberSpecializationInfo();
2525      assert(MSInfo && "No member specialization information?");
2526
2527      if (MSInfo->getTemplateSpecializationKind()
2528            == TSK_ExplicitSpecialization)
2529        continue;
2530
2531      if (CheckSpecializationInstantiationRedecl(
2532            PointOfInstantiation, TSK, Enum,
2533            MSInfo->getTemplateSpecializationKind(),
2534            MSInfo->getPointOfInstantiation(), SuppressNew) ||
2535          SuppressNew)
2536        continue;
2537
2538      if (Enum->getDefinition())
2539        continue;
2540
2541      EnumDecl *Pattern = Enum->getInstantiatedFromMemberEnum();
2542      assert(Pattern && "Missing instantiated-from-template information");
2543
2544      if (TSK == TSK_ExplicitInstantiationDefinition) {
2545        if (!Pattern->getDefinition())
2546          continue;
2547
2548        InstantiateEnum(PointOfInstantiation, Enum, Pattern, TemplateArgs, TSK);
2549      } else {
2550        MSInfo->setTemplateSpecializationKind(TSK);
2551        MSInfo->setPointOfInstantiation(PointOfInstantiation);
2552      }
2553    }
2554  }
2555}
2556
2557/// \brief Instantiate the definitions of all of the members of the
2558/// given class template specialization, which was named as part of an
2559/// explicit instantiation.
2560void
2561Sema::InstantiateClassTemplateSpecializationMembers(
2562                                           SourceLocation PointOfInstantiation,
2563                            ClassTemplateSpecializationDecl *ClassTemplateSpec,
2564                                               TemplateSpecializationKind TSK) {
2565  // C++0x [temp.explicit]p7:
2566  //   An explicit instantiation that names a class template
2567  //   specialization is an explicit instantion of the same kind
2568  //   (declaration or definition) of each of its members (not
2569  //   including members inherited from base classes) that has not
2570  //   been previously explicitly specialized in the translation unit
2571  //   containing the explicit instantiation, except as described
2572  //   below.
2573  InstantiateClassMembers(PointOfInstantiation, ClassTemplateSpec,
2574                          getTemplateInstantiationArgs(ClassTemplateSpec),
2575                          TSK);
2576}
2577
2578StmtResult
2579Sema::SubstStmt(Stmt *S, const MultiLevelTemplateArgumentList &TemplateArgs) {
2580  if (!S)
2581    return Owned(S);
2582
2583  TemplateInstantiator Instantiator(*this, TemplateArgs,
2584                                    SourceLocation(),
2585                                    DeclarationName());
2586  return Instantiator.TransformStmt(S);
2587}
2588
2589ExprResult
2590Sema::SubstExpr(Expr *E, const MultiLevelTemplateArgumentList &TemplateArgs) {
2591  if (!E)
2592    return Owned(E);
2593
2594  TemplateInstantiator Instantiator(*this, TemplateArgs,
2595                                    SourceLocation(),
2596                                    DeclarationName());
2597  return Instantiator.TransformExpr(E);
2598}
2599
2600ExprResult Sema::SubstInitializer(Expr *Init,
2601                          const MultiLevelTemplateArgumentList &TemplateArgs,
2602                          bool CXXDirectInit) {
2603  TemplateInstantiator Instantiator(*this, TemplateArgs,
2604                                    SourceLocation(),
2605                                    DeclarationName());
2606  return Instantiator.TransformInitializer(Init, CXXDirectInit);
2607}
2608
2609bool Sema::SubstExprs(Expr **Exprs, unsigned NumExprs, bool IsCall,
2610                      const MultiLevelTemplateArgumentList &TemplateArgs,
2611                      SmallVectorImpl<Expr *> &Outputs) {
2612  if (NumExprs == 0)
2613    return false;
2614
2615  TemplateInstantiator Instantiator(*this, TemplateArgs,
2616                                    SourceLocation(),
2617                                    DeclarationName());
2618  return Instantiator.TransformExprs(Exprs, NumExprs, IsCall, Outputs);
2619}
2620
2621NestedNameSpecifierLoc
2622Sema::SubstNestedNameSpecifierLoc(NestedNameSpecifierLoc NNS,
2623                        const MultiLevelTemplateArgumentList &TemplateArgs) {
2624  if (!NNS)
2625    return NestedNameSpecifierLoc();
2626
2627  TemplateInstantiator Instantiator(*this, TemplateArgs, NNS.getBeginLoc(),
2628                                    DeclarationName());
2629  return Instantiator.TransformNestedNameSpecifierLoc(NNS);
2630}
2631
2632/// \brief Do template substitution on declaration name info.
2633DeclarationNameInfo
2634Sema::SubstDeclarationNameInfo(const DeclarationNameInfo &NameInfo,
2635                         const MultiLevelTemplateArgumentList &TemplateArgs) {
2636  TemplateInstantiator Instantiator(*this, TemplateArgs, NameInfo.getLoc(),
2637                                    NameInfo.getName());
2638  return Instantiator.TransformDeclarationNameInfo(NameInfo);
2639}
2640
2641TemplateName
2642Sema::SubstTemplateName(NestedNameSpecifierLoc QualifierLoc,
2643                        TemplateName Name, SourceLocation Loc,
2644                        const MultiLevelTemplateArgumentList &TemplateArgs) {
2645  TemplateInstantiator Instantiator(*this, TemplateArgs, Loc,
2646                                    DeclarationName());
2647  CXXScopeSpec SS;
2648  SS.Adopt(QualifierLoc);
2649  return Instantiator.TransformTemplateName(SS, Name, Loc);
2650}
2651
2652bool Sema::Subst(const TemplateArgumentLoc *Args, unsigned NumArgs,
2653                 TemplateArgumentListInfo &Result,
2654                 const MultiLevelTemplateArgumentList &TemplateArgs) {
2655  TemplateInstantiator Instantiator(*this, TemplateArgs, SourceLocation(),
2656                                    DeclarationName());
2657
2658  return Instantiator.TransformTemplateArguments(Args, NumArgs, Result);
2659}
2660
2661
2662static const Decl* getCanonicalParmVarDecl(const Decl *D) {
2663  // When storing ParmVarDecls in the local instantiation scope, we always
2664  // want to use the ParmVarDecl from the canonical function declaration,
2665  // since the map is then valid for any redeclaration or definition of that
2666  // function.
2667  if (const ParmVarDecl *PV = dyn_cast<ParmVarDecl>(D)) {
2668    if (const FunctionDecl *FD = dyn_cast<FunctionDecl>(PV->getDeclContext())) {
2669      unsigned i = PV->getFunctionScopeIndex();
2670      return FD->getCanonicalDecl()->getParamDecl(i);
2671    }
2672  }
2673  return D;
2674}
2675
2676
2677llvm::PointerUnion<Decl *, LocalInstantiationScope::DeclArgumentPack *> *
2678LocalInstantiationScope::findInstantiationOf(const Decl *D) {
2679  D = getCanonicalParmVarDecl(D);
2680  for (LocalInstantiationScope *Current = this; Current;
2681       Current = Current->Outer) {
2682
2683    // Check if we found something within this scope.
2684    const Decl *CheckD = D;
2685    do {
2686      LocalDeclsMap::iterator Found = Current->LocalDecls.find(CheckD);
2687      if (Found != Current->LocalDecls.end())
2688        return &Found->second;
2689
2690      // If this is a tag declaration, it's possible that we need to look for
2691      // a previous declaration.
2692      if (const TagDecl *Tag = dyn_cast<TagDecl>(CheckD))
2693        CheckD = Tag->getPreviousDecl();
2694      else
2695        CheckD = 0;
2696    } while (CheckD);
2697
2698    // If we aren't combined with our outer scope, we're done.
2699    if (!Current->CombineWithOuterScope)
2700      break;
2701  }
2702
2703  // If we didn't find the decl, then we either have a sema bug, or we have a
2704  // forward reference to a label declaration.  Return null to indicate that
2705  // we have an uninstantiated label.
2706  assert(isa<LabelDecl>(D) && "declaration not instantiated in this scope");
2707  return 0;
2708}
2709
2710void LocalInstantiationScope::InstantiatedLocal(const Decl *D, Decl *Inst) {
2711  D = getCanonicalParmVarDecl(D);
2712  llvm::PointerUnion<Decl *, DeclArgumentPack *> &Stored = LocalDecls[D];
2713  if (Stored.isNull())
2714    Stored = Inst;
2715  else if (DeclArgumentPack *Pack = Stored.dyn_cast<DeclArgumentPack *>())
2716    Pack->push_back(Inst);
2717  else
2718    assert(Stored.get<Decl *>() == Inst && "Already instantiated this local");
2719}
2720
2721void LocalInstantiationScope::InstantiatedLocalPackArg(const Decl *D,
2722                                                       Decl *Inst) {
2723  D = getCanonicalParmVarDecl(D);
2724  DeclArgumentPack *Pack = LocalDecls[D].get<DeclArgumentPack *>();
2725  Pack->push_back(Inst);
2726}
2727
2728void LocalInstantiationScope::MakeInstantiatedLocalArgPack(const Decl *D) {
2729  D = getCanonicalParmVarDecl(D);
2730  llvm::PointerUnion<Decl *, DeclArgumentPack *> &Stored = LocalDecls[D];
2731  assert(Stored.isNull() && "Already instantiated this local");
2732  DeclArgumentPack *Pack = new DeclArgumentPack;
2733  Stored = Pack;
2734  ArgumentPacks.push_back(Pack);
2735}
2736
2737void LocalInstantiationScope::SetPartiallySubstitutedPack(NamedDecl *Pack,
2738                                          const TemplateArgument *ExplicitArgs,
2739                                                    unsigned NumExplicitArgs) {
2740  assert((!PartiallySubstitutedPack || PartiallySubstitutedPack == Pack) &&
2741         "Already have a partially-substituted pack");
2742  assert((!PartiallySubstitutedPack
2743          || NumArgsInPartiallySubstitutedPack == NumExplicitArgs) &&
2744         "Wrong number of arguments in partially-substituted pack");
2745  PartiallySubstitutedPack = Pack;
2746  ArgsInPartiallySubstitutedPack = ExplicitArgs;
2747  NumArgsInPartiallySubstitutedPack = NumExplicitArgs;
2748}
2749
2750NamedDecl *LocalInstantiationScope::getPartiallySubstitutedPack(
2751                                         const TemplateArgument **ExplicitArgs,
2752                                              unsigned *NumExplicitArgs) const {
2753  if (ExplicitArgs)
2754    *ExplicitArgs = 0;
2755  if (NumExplicitArgs)
2756    *NumExplicitArgs = 0;
2757
2758  for (const LocalInstantiationScope *Current = this; Current;
2759       Current = Current->Outer) {
2760    if (Current->PartiallySubstitutedPack) {
2761      if (ExplicitArgs)
2762        *ExplicitArgs = Current->ArgsInPartiallySubstitutedPack;
2763      if (NumExplicitArgs)
2764        *NumExplicitArgs = Current->NumArgsInPartiallySubstitutedPack;
2765
2766      return Current->PartiallySubstitutedPack;
2767    }
2768
2769    if (!Current->CombineWithOuterScope)
2770      break;
2771  }
2772
2773  return 0;
2774}
2775