1 //===- NestedNameSpecifier.cpp - C++ nested name specifiers ---------------===//
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 //
10 //  This file defines the NestedNameSpecifier class, which represents
11 //  a C++ nested-name-specifier.
12 //
13 //===----------------------------------------------------------------------===//
14 
15 #include "clang/AST/NestedNameSpecifier.h"
16 #include "clang/AST/ASTContext.h"
17 #include "clang/AST/Decl.h"
18 #include "clang/AST/DeclCXX.h"
19 #include "clang/AST/PrettyPrinter.h"
20 #include "clang/AST/TemplateName.h"
21 #include "clang/AST/Type.h"
22 #include "clang/AST/TypeLoc.h"
23 #include "clang/Basic/LLVM.h"
24 #include "clang/Basic/LangOptions.h"
25 #include "clang/Basic/SourceLocation.h"
26 #include "llvm/ADT/FoldingSet.h"
27 #include "llvm/ADT/SmallVector.h"
28 #include "llvm/Support/Casting.h"
29 #include "llvm/Support/Compiler.h"
30 #include "llvm/Support/ErrorHandling.h"
31 #include "llvm/Support/raw_ostream.h"
32 #include <algorithm>
33 #include <cassert>
34 #include <cstdlib>
35 #include <cstring>
36 
37 using namespace clang;
38 
39 NestedNameSpecifier *
40 NestedNameSpecifier::FindOrInsert(const ASTContext &Context,
41                                   const NestedNameSpecifier &Mockup) {
42   llvm::FoldingSetNodeID ID;
43   Mockup.Profile(ID);
44 
45   void *InsertPos = nullptr;
46   NestedNameSpecifier *NNS
47     = Context.NestedNameSpecifiers.FindNodeOrInsertPos(ID, InsertPos);
48   if (!NNS) {
49     NNS =
50         new (Context, alignof(NestedNameSpecifier)) NestedNameSpecifier(Mockup);
51     Context.NestedNameSpecifiers.InsertNode(NNS, InsertPos);
52   }
53 
54   return NNS;
55 }
56 
57 NestedNameSpecifier *
58 NestedNameSpecifier::Create(const ASTContext &Context,
59                             NestedNameSpecifier *Prefix, IdentifierInfo *II) {
60   assert(II && "Identifier cannot be NULL");
61   assert((!Prefix || Prefix->isDependent()) && "Prefix must be dependent");
62 
63   NestedNameSpecifier Mockup;
64   Mockup.Prefix.setPointer(Prefix);
65   Mockup.Prefix.setInt(StoredIdentifier);
66   Mockup.Specifier = II;
67   return FindOrInsert(Context, Mockup);
68 }
69 
70 NestedNameSpecifier *
71 NestedNameSpecifier::Create(const ASTContext &Context,
72                             NestedNameSpecifier *Prefix,
73                             const NamespaceDecl *NS) {
74   assert(NS && "Namespace cannot be NULL");
75   assert((!Prefix ||
76           (Prefix->getAsType() == nullptr &&
77            Prefix->getAsIdentifier() == nullptr)) &&
78          "Broken nested name specifier");
79   NestedNameSpecifier Mockup;
80   Mockup.Prefix.setPointer(Prefix);
81   Mockup.Prefix.setInt(StoredDecl);
82   Mockup.Specifier = const_cast<NamespaceDecl *>(NS);
83   return FindOrInsert(Context, Mockup);
84 }
85 
86 NestedNameSpecifier *
87 NestedNameSpecifier::Create(const ASTContext &Context,
88                             NestedNameSpecifier *Prefix,
89                             NamespaceAliasDecl *Alias) {
90   assert(Alias && "Namespace alias cannot be NULL");
91   assert((!Prefix ||
92           (Prefix->getAsType() == nullptr &&
93            Prefix->getAsIdentifier() == nullptr)) &&
94          "Broken nested name specifier");
95   NestedNameSpecifier Mockup;
96   Mockup.Prefix.setPointer(Prefix);
97   Mockup.Prefix.setInt(StoredDecl);
98   Mockup.Specifier = Alias;
99   return FindOrInsert(Context, Mockup);
100 }
101 
102 NestedNameSpecifier *
103 NestedNameSpecifier::Create(const ASTContext &Context,
104                             NestedNameSpecifier *Prefix,
105                             bool Template, const Type *T) {
106   assert(T && "Type cannot be NULL");
107   NestedNameSpecifier Mockup;
108   Mockup.Prefix.setPointer(Prefix);
109   Mockup.Prefix.setInt(Template? StoredTypeSpecWithTemplate : StoredTypeSpec);
110   Mockup.Specifier = const_cast<Type*>(T);
111   return FindOrInsert(Context, Mockup);
112 }
113 
114 NestedNameSpecifier *
115 NestedNameSpecifier::Create(const ASTContext &Context, IdentifierInfo *II) {
116   assert(II && "Identifier cannot be NULL");
117   NestedNameSpecifier Mockup;
118   Mockup.Prefix.setPointer(nullptr);
119   Mockup.Prefix.setInt(StoredIdentifier);
120   Mockup.Specifier = II;
121   return FindOrInsert(Context, Mockup);
122 }
123 
124 NestedNameSpecifier *
125 NestedNameSpecifier::GlobalSpecifier(const ASTContext &Context) {
126   if (!Context.GlobalNestedNameSpecifier)
127     Context.GlobalNestedNameSpecifier =
128         new (Context, alignof(NestedNameSpecifier)) NestedNameSpecifier();
129   return Context.GlobalNestedNameSpecifier;
130 }
131 
132 NestedNameSpecifier *
133 NestedNameSpecifier::SuperSpecifier(const ASTContext &Context,
134                                     CXXRecordDecl *RD) {
135   NestedNameSpecifier Mockup;
136   Mockup.Prefix.setPointer(nullptr);
137   Mockup.Prefix.setInt(StoredDecl);
138   Mockup.Specifier = RD;
139   return FindOrInsert(Context, Mockup);
140 }
141 
142 NestedNameSpecifier::SpecifierKind NestedNameSpecifier::getKind() const {
143   if (!Specifier)
144     return Global;
145 
146   switch (Prefix.getInt()) {
147   case StoredIdentifier:
148     return Identifier;
149 
150   case StoredDecl: {
151     NamedDecl *ND = static_cast<NamedDecl *>(Specifier);
152     if (isa<CXXRecordDecl>(ND))
153       return Super;
154     return isa<NamespaceDecl>(ND) ? Namespace : NamespaceAlias;
155   }
156 
157   case StoredTypeSpec:
158     return TypeSpec;
159 
160   case StoredTypeSpecWithTemplate:
161     return TypeSpecWithTemplate;
162   }
163 
164   llvm_unreachable("Invalid NNS Kind!");
165 }
166 
167 /// Retrieve the namespace stored in this nested name specifier.
168 NamespaceDecl *NestedNameSpecifier::getAsNamespace() const {
169   if (Prefix.getInt() == StoredDecl)
170     return dyn_cast<NamespaceDecl>(static_cast<NamedDecl *>(Specifier));
171 
172   return nullptr;
173 }
174 
175 /// Retrieve the namespace alias stored in this nested name specifier.
176 NamespaceAliasDecl *NestedNameSpecifier::getAsNamespaceAlias() const {
177   if (Prefix.getInt() == StoredDecl)
178     return dyn_cast<NamespaceAliasDecl>(static_cast<NamedDecl *>(Specifier));
179 
180   return nullptr;
181 }
182 
183 /// Retrieve the record declaration stored in this nested name specifier.
184 CXXRecordDecl *NestedNameSpecifier::getAsRecordDecl() const {
185   switch (Prefix.getInt()) {
186   case StoredIdentifier:
187     return nullptr;
188 
189   case StoredDecl:
190     return dyn_cast<CXXRecordDecl>(static_cast<NamedDecl *>(Specifier));
191 
192   case StoredTypeSpec:
193   case StoredTypeSpecWithTemplate:
194     return getAsType()->getAsCXXRecordDecl();
195   }
196 
197   llvm_unreachable("Invalid NNS Kind!");
198 }
199 
200 /// Whether this nested name specifier refers to a dependent
201 /// type or not.
202 bool NestedNameSpecifier::isDependent() const {
203   switch (getKind()) {
204   case Identifier:
205     // Identifier specifiers always represent dependent types
206     return true;
207 
208   case Namespace:
209   case NamespaceAlias:
210   case Global:
211     return false;
212 
213   case Super: {
214     CXXRecordDecl *RD = static_cast<CXXRecordDecl *>(Specifier);
215     for (const auto &Base : RD->bases())
216       if (Base.getType()->isDependentType())
217         return true;
218 
219     return false;
220   }
221 
222   case TypeSpec:
223   case TypeSpecWithTemplate:
224     return getAsType()->isDependentType();
225   }
226 
227   llvm_unreachable("Invalid NNS Kind!");
228 }
229 
230 /// Whether this nested name specifier refers to a dependent
231 /// type or not.
232 bool NestedNameSpecifier::isInstantiationDependent() const {
233   switch (getKind()) {
234   case Identifier:
235     // Identifier specifiers always represent dependent types
236     return true;
237 
238   case Namespace:
239   case NamespaceAlias:
240   case Global:
241   case Super:
242     return false;
243 
244   case TypeSpec:
245   case TypeSpecWithTemplate:
246     return getAsType()->isInstantiationDependentType();
247   }
248 
249   llvm_unreachable("Invalid NNS Kind!");
250 }
251 
252 bool NestedNameSpecifier::containsUnexpandedParameterPack() const {
253   switch (getKind()) {
254   case Identifier:
255     return getPrefix() && getPrefix()->containsUnexpandedParameterPack();
256 
257   case Namespace:
258   case NamespaceAlias:
259   case Global:
260   case Super:
261     return false;
262 
263   case TypeSpec:
264   case TypeSpecWithTemplate:
265     return getAsType()->containsUnexpandedParameterPack();
266   }
267 
268   llvm_unreachable("Invalid NNS Kind!");
269 }
270 
271 /// Print this nested name specifier to the given output
272 /// stream.
273 void
274 NestedNameSpecifier::print(raw_ostream &OS,
275                            const PrintingPolicy &Policy) const {
276   if (getPrefix())
277     getPrefix()->print(OS, Policy);
278 
279   switch (getKind()) {
280   case Identifier:
281     OS << getAsIdentifier()->getName();
282     break;
283 
284   case Namespace:
285     if (getAsNamespace()->isAnonymousNamespace())
286       return;
287 
288     OS << getAsNamespace()->getName();
289     break;
290 
291   case NamespaceAlias:
292     OS << getAsNamespaceAlias()->getName();
293     break;
294 
295   case Global:
296     break;
297 
298   case Super:
299     OS << "__super";
300     break;
301 
302   case TypeSpecWithTemplate:
303     OS << "template ";
304     // Fall through to print the type.
305     LLVM_FALLTHROUGH;
306 
307   case TypeSpec: {
308     const Type *T = getAsType();
309 
310     PrintingPolicy InnerPolicy(Policy);
311     InnerPolicy.SuppressScope = true;
312 
313     // Nested-name-specifiers are intended to contain minimally-qualified
314     // types. An actual ElaboratedType will not occur, since we'll store
315     // just the type that is referred to in the nested-name-specifier (e.g.,
316     // a TypedefType, TagType, etc.). However, when we are dealing with
317     // dependent template-id types (e.g., Outer<T>::template Inner<U>),
318     // the type requires its own nested-name-specifier for uniqueness, so we
319     // suppress that nested-name-specifier during printing.
320     assert(!isa<ElaboratedType>(T) &&
321            "Elaborated type in nested-name-specifier");
322     if (const TemplateSpecializationType *SpecType
323           = dyn_cast<TemplateSpecializationType>(T)) {
324       // Print the template name without its corresponding
325       // nested-name-specifier.
326       SpecType->getTemplateName().print(OS, InnerPolicy, true);
327 
328       // Print the template argument list.
329       printTemplateArgumentList(OS, SpecType->template_arguments(),
330                                 InnerPolicy);
331     } else {
332       // Print the type normally
333       QualType(T, 0).print(OS, InnerPolicy);
334     }
335     break;
336   }
337   }
338 
339   OS << "::";
340 }
341 
342 LLVM_DUMP_METHOD void NestedNameSpecifier::dump(const LangOptions &LO) const {
343   dump(llvm::errs(), LO);
344 }
345 
346 LLVM_DUMP_METHOD void NestedNameSpecifier::dump() const { dump(llvm::errs()); }
347 
348 LLVM_DUMP_METHOD void NestedNameSpecifier::dump(llvm::raw_ostream &OS) const {
349   LangOptions LO;
350   dump(OS, LO);
351 }
352 
353 LLVM_DUMP_METHOD void NestedNameSpecifier::dump(llvm::raw_ostream &OS,
354                                                 const LangOptions &LO) const {
355   print(OS, PrintingPolicy(LO));
356 }
357 
358 unsigned
359 NestedNameSpecifierLoc::getLocalDataLength(NestedNameSpecifier *Qualifier) {
360   assert(Qualifier && "Expected a non-NULL qualifier");
361 
362   // Location of the trailing '::'.
363   unsigned Length = sizeof(unsigned);
364 
365   switch (Qualifier->getKind()) {
366   case NestedNameSpecifier::Global:
367     // Nothing more to add.
368     break;
369 
370   case NestedNameSpecifier::Identifier:
371   case NestedNameSpecifier::Namespace:
372   case NestedNameSpecifier::NamespaceAlias:
373   case NestedNameSpecifier::Super:
374     // The location of the identifier or namespace name.
375     Length += sizeof(unsigned);
376     break;
377 
378   case NestedNameSpecifier::TypeSpecWithTemplate:
379   case NestedNameSpecifier::TypeSpec:
380     // The "void*" that points at the TypeLoc data.
381     // Note: the 'template' keyword is part of the TypeLoc.
382     Length += sizeof(void *);
383     break;
384   }
385 
386   return Length;
387 }
388 
389 unsigned
390 NestedNameSpecifierLoc::getDataLength(NestedNameSpecifier *Qualifier) {
391   unsigned Length = 0;
392   for (; Qualifier; Qualifier = Qualifier->getPrefix())
393     Length += getLocalDataLength(Qualifier);
394   return Length;
395 }
396 
397 /// Load a (possibly unaligned) source location from a given address
398 /// and offset.
399 static SourceLocation LoadSourceLocation(void *Data, unsigned Offset) {
400   unsigned Raw;
401   memcpy(&Raw, static_cast<char *>(Data) + Offset, sizeof(unsigned));
402   return SourceLocation::getFromRawEncoding(Raw);
403 }
404 
405 /// Load a (possibly unaligned) pointer from a given address and
406 /// offset.
407 static void *LoadPointer(void *Data, unsigned Offset) {
408   void *Result;
409   memcpy(&Result, static_cast<char *>(Data) + Offset, sizeof(void*));
410   return Result;
411 }
412 
413 SourceRange NestedNameSpecifierLoc::getSourceRange() const {
414   if (!Qualifier)
415     return SourceRange();
416 
417   NestedNameSpecifierLoc First = *this;
418   while (NestedNameSpecifierLoc Prefix = First.getPrefix())
419     First = Prefix;
420 
421   return SourceRange(First.getLocalSourceRange().getBegin(),
422                      getLocalSourceRange().getEnd());
423 }
424 
425 SourceRange NestedNameSpecifierLoc::getLocalSourceRange() const {
426   if (!Qualifier)
427     return SourceRange();
428 
429   unsigned Offset = getDataLength(Qualifier->getPrefix());
430   switch (Qualifier->getKind()) {
431   case NestedNameSpecifier::Global:
432     return LoadSourceLocation(Data, Offset);
433 
434   case NestedNameSpecifier::Identifier:
435   case NestedNameSpecifier::Namespace:
436   case NestedNameSpecifier::NamespaceAlias:
437   case NestedNameSpecifier::Super:
438     return SourceRange(LoadSourceLocation(Data, Offset),
439                        LoadSourceLocation(Data, Offset + sizeof(unsigned)));
440 
441   case NestedNameSpecifier::TypeSpecWithTemplate:
442   case NestedNameSpecifier::TypeSpec: {
443     // The "void*" that points at the TypeLoc data.
444     // Note: the 'template' keyword is part of the TypeLoc.
445     void *TypeData = LoadPointer(Data, Offset);
446     TypeLoc TL(Qualifier->getAsType(), TypeData);
447     return SourceRange(TL.getBeginLoc(),
448                        LoadSourceLocation(Data, Offset + sizeof(void*)));
449   }
450   }
451 
452   llvm_unreachable("Invalid NNS Kind!");
453 }
454 
455 TypeLoc NestedNameSpecifierLoc::getTypeLoc() const {
456   assert((Qualifier->getKind() == NestedNameSpecifier::TypeSpec ||
457           Qualifier->getKind() == NestedNameSpecifier::TypeSpecWithTemplate) &&
458          "Nested-name-specifier location is not a type");
459 
460   // The "void*" that points at the TypeLoc data.
461   unsigned Offset = getDataLength(Qualifier->getPrefix());
462   void *TypeData = LoadPointer(Data, Offset);
463   return TypeLoc(Qualifier->getAsType(), TypeData);
464 }
465 
466 static void Append(char *Start, char *End, char *&Buffer, unsigned &BufferSize,
467               unsigned &BufferCapacity) {
468   if (Start == End)
469     return;
470 
471   if (BufferSize + (End - Start) > BufferCapacity) {
472     // Reallocate the buffer.
473     unsigned NewCapacity = std::max(
474         (unsigned)(BufferCapacity ? BufferCapacity * 2 : sizeof(void *) * 2),
475         (unsigned)(BufferSize + (End - Start)));
476     char *NewBuffer = static_cast<char *>(llvm::safe_malloc(NewCapacity));
477     if (BufferCapacity) {
478       memcpy(NewBuffer, Buffer, BufferSize);
479       free(Buffer);
480     }
481     Buffer = NewBuffer;
482     BufferCapacity = NewCapacity;
483   }
484 
485   memcpy(Buffer + BufferSize, Start, End - Start);
486   BufferSize += End-Start;
487 }
488 
489 /// Save a source location to the given buffer.
490 static void SaveSourceLocation(SourceLocation Loc, char *&Buffer,
491                                unsigned &BufferSize, unsigned &BufferCapacity) {
492   unsigned Raw = Loc.getRawEncoding();
493   Append(reinterpret_cast<char *>(&Raw),
494          reinterpret_cast<char *>(&Raw) + sizeof(unsigned),
495          Buffer, BufferSize, BufferCapacity);
496 }
497 
498 /// Save a pointer to the given buffer.
499 static void SavePointer(void *Ptr, char *&Buffer, unsigned &BufferSize,
500                         unsigned &BufferCapacity) {
501   Append(reinterpret_cast<char *>(&Ptr),
502          reinterpret_cast<char *>(&Ptr) + sizeof(void *),
503          Buffer, BufferSize, BufferCapacity);
504 }
505 
506 NestedNameSpecifierLocBuilder::
507 NestedNameSpecifierLocBuilder(const NestedNameSpecifierLocBuilder &Other)
508     : Representation(Other.Representation) {
509   if (!Other.Buffer)
510     return;
511 
512   if (Other.BufferCapacity == 0) {
513     // Shallow copy is okay.
514     Buffer = Other.Buffer;
515     BufferSize = Other.BufferSize;
516     return;
517   }
518 
519   // Deep copy
520   Append(Other.Buffer, Other.Buffer + Other.BufferSize, Buffer, BufferSize,
521          BufferCapacity);
522 }
523 
524 NestedNameSpecifierLocBuilder &
525 NestedNameSpecifierLocBuilder::
526 operator=(const NestedNameSpecifierLocBuilder &Other) {
527   Representation = Other.Representation;
528 
529   if (Buffer && Other.Buffer && BufferCapacity >= Other.BufferSize) {
530     // Re-use our storage.
531     BufferSize = Other.BufferSize;
532     memcpy(Buffer, Other.Buffer, BufferSize);
533     return *this;
534   }
535 
536   // Free our storage, if we have any.
537   if (BufferCapacity) {
538     free(Buffer);
539     BufferCapacity = 0;
540   }
541 
542   if (!Other.Buffer) {
543     // Empty.
544     Buffer = nullptr;
545     BufferSize = 0;
546     return *this;
547   }
548 
549   if (Other.BufferCapacity == 0) {
550     // Shallow copy is okay.
551     Buffer = Other.Buffer;
552     BufferSize = Other.BufferSize;
553     return *this;
554   }
555 
556   // Deep copy.
557   BufferSize = 0;
558   Append(Other.Buffer, Other.Buffer + Other.BufferSize, Buffer, BufferSize,
559          BufferCapacity);
560   return *this;
561 }
562 
563 void NestedNameSpecifierLocBuilder::Extend(ASTContext &Context,
564                                            SourceLocation TemplateKWLoc,
565                                            TypeLoc TL,
566                                            SourceLocation ColonColonLoc) {
567   Representation = NestedNameSpecifier::Create(Context, Representation,
568                                                TemplateKWLoc.isValid(),
569                                                TL.getTypePtr());
570 
571   // Push source-location info into the buffer.
572   SavePointer(TL.getOpaqueData(), Buffer, BufferSize, BufferCapacity);
573   SaveSourceLocation(ColonColonLoc, Buffer, BufferSize, BufferCapacity);
574 }
575 
576 void NestedNameSpecifierLocBuilder::Extend(ASTContext &Context,
577                                            IdentifierInfo *Identifier,
578                                            SourceLocation IdentifierLoc,
579                                            SourceLocation ColonColonLoc) {
580   Representation = NestedNameSpecifier::Create(Context, Representation,
581                                                Identifier);
582 
583   // Push source-location info into the buffer.
584   SaveSourceLocation(IdentifierLoc, Buffer, BufferSize, BufferCapacity);
585   SaveSourceLocation(ColonColonLoc, Buffer, BufferSize, BufferCapacity);
586 }
587 
588 void NestedNameSpecifierLocBuilder::Extend(ASTContext &Context,
589                                            NamespaceDecl *Namespace,
590                                            SourceLocation NamespaceLoc,
591                                            SourceLocation ColonColonLoc) {
592   Representation = NestedNameSpecifier::Create(Context, Representation,
593                                                Namespace);
594 
595   // Push source-location info into the buffer.
596   SaveSourceLocation(NamespaceLoc, Buffer, BufferSize, BufferCapacity);
597   SaveSourceLocation(ColonColonLoc, Buffer, BufferSize, BufferCapacity);
598 }
599 
600 void NestedNameSpecifierLocBuilder::Extend(ASTContext &Context,
601                                            NamespaceAliasDecl *Alias,
602                                            SourceLocation AliasLoc,
603                                            SourceLocation ColonColonLoc) {
604   Representation = NestedNameSpecifier::Create(Context, Representation, Alias);
605 
606   // Push source-location info into the buffer.
607   SaveSourceLocation(AliasLoc, Buffer, BufferSize, BufferCapacity);
608   SaveSourceLocation(ColonColonLoc, Buffer, BufferSize, BufferCapacity);
609 }
610 
611 void NestedNameSpecifierLocBuilder::MakeGlobal(ASTContext &Context,
612                                                SourceLocation ColonColonLoc) {
613   assert(!Representation && "Already have a nested-name-specifier!?");
614   Representation = NestedNameSpecifier::GlobalSpecifier(Context);
615 
616   // Push source-location info into the buffer.
617   SaveSourceLocation(ColonColonLoc, Buffer, BufferSize, BufferCapacity);
618 }
619 
620 void NestedNameSpecifierLocBuilder::MakeSuper(ASTContext &Context,
621                                               CXXRecordDecl *RD,
622                                               SourceLocation SuperLoc,
623                                               SourceLocation ColonColonLoc) {
624   Representation = NestedNameSpecifier::SuperSpecifier(Context, RD);
625 
626   // Push source-location info into the buffer.
627   SaveSourceLocation(SuperLoc, Buffer, BufferSize, BufferCapacity);
628   SaveSourceLocation(ColonColonLoc, Buffer, BufferSize, BufferCapacity);
629 }
630 
631 void NestedNameSpecifierLocBuilder::MakeTrivial(ASTContext &Context,
632                                                 NestedNameSpecifier *Qualifier,
633                                                 SourceRange R) {
634   Representation = Qualifier;
635 
636   // Construct bogus (but well-formed) source information for the
637   // nested-name-specifier.
638   BufferSize = 0;
639   SmallVector<NestedNameSpecifier *, 4> Stack;
640   for (NestedNameSpecifier *NNS = Qualifier; NNS; NNS = NNS->getPrefix())
641     Stack.push_back(NNS);
642   while (!Stack.empty()) {
643     NestedNameSpecifier *NNS = Stack.pop_back_val();
644     switch (NNS->getKind()) {
645       case NestedNameSpecifier::Identifier:
646       case NestedNameSpecifier::Namespace:
647       case NestedNameSpecifier::NamespaceAlias:
648         SaveSourceLocation(R.getBegin(), Buffer, BufferSize, BufferCapacity);
649         break;
650 
651       case NestedNameSpecifier::TypeSpec:
652       case NestedNameSpecifier::TypeSpecWithTemplate: {
653         TypeSourceInfo *TSInfo
654         = Context.getTrivialTypeSourceInfo(QualType(NNS->getAsType(), 0),
655                                            R.getBegin());
656         SavePointer(TSInfo->getTypeLoc().getOpaqueData(), Buffer, BufferSize,
657                     BufferCapacity);
658         break;
659       }
660 
661       case NestedNameSpecifier::Global:
662       case NestedNameSpecifier::Super:
663         break;
664     }
665 
666     // Save the location of the '::'.
667     SaveSourceLocation(Stack.empty()? R.getEnd() : R.getBegin(),
668                        Buffer, BufferSize, BufferCapacity);
669   }
670 }
671 
672 void NestedNameSpecifierLocBuilder::Adopt(NestedNameSpecifierLoc Other) {
673   if (BufferCapacity)
674     free(Buffer);
675 
676   if (!Other) {
677     Representation = nullptr;
678     BufferSize = 0;
679     return;
680   }
681 
682   // Rather than copying the data (which is wasteful), "adopt" the
683   // pointer (which points into the ASTContext) but set the capacity to zero to
684   // indicate that we don't own it.
685   Representation = Other.getNestedNameSpecifier();
686   Buffer = static_cast<char *>(Other.getOpaqueData());
687   BufferSize = Other.getDataLength();
688   BufferCapacity = 0;
689 }
690 
691 NestedNameSpecifierLoc
692 NestedNameSpecifierLocBuilder::getWithLocInContext(ASTContext &Context) const {
693   if (!Representation)
694     return NestedNameSpecifierLoc();
695 
696   // If we adopted our data pointer from elsewhere in the AST context, there's
697   // no need to copy the memory.
698   if (BufferCapacity == 0)
699     return NestedNameSpecifierLoc(Representation, Buffer);
700 
701   // FIXME: After copying the source-location information, should we free
702   // our (temporary) buffer and adopt the ASTContext-allocated memory?
703   // Doing so would optimize repeated calls to getWithLocInContext().
704   void *Mem = Context.Allocate(BufferSize, alignof(void *));
705   memcpy(Mem, Buffer, BufferSize);
706   return NestedNameSpecifierLoc(Representation, Mem);
707 }
708