xref: /freebsd/contrib/llvm-project/clang/lib/AST/NestedNameSpecifier.cpp (revision 48daf251932bd09f2dc1356aa1cf72b043f1f892) 
1 //===- NestedNameSpecifier.cpp - C++ nested name specifiers ---------------===//
2 //
3 // Part of the LLVM Project, under the Apache License v2.0 with LLVM Exceptions.
4 // See https://llvm.org/LICENSE.txt for license information.
5 // SPDX-License-Identifier: Apache-2.0 WITH LLVM-exception
6 //
7 //===----------------------------------------------------------------------===//
8 //
9 //  This file defines the NestedNameSpecifier class, which represents
10 //  a C++ nested-name-specifier.
11 //
12 //===----------------------------------------------------------------------===//
13 
14 #include "clang/AST/NestedNameSpecifier.h"
15 #include "clang/AST/ASTContext.h"
16 #include "clang/AST/Decl.h"
17 #include "clang/AST/DeclCXX.h"
18 #include "clang/AST/DeclTemplate.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 NestedNameSpecifier::print(raw_ostream &OS, const PrintingPolicy &Policy,
274                                 bool ResolveTemplateArguments) const {
275   if (getPrefix())
276     getPrefix()->print(OS, Policy);
277 
278   switch (getKind()) {
279   case Identifier:
280     OS << getAsIdentifier()->getName();
281     break;
282 
283   case Namespace:
284     if (getAsNamespace()->isAnonymousNamespace())
285       return;
286 
287     OS << getAsNamespace()->getName();
288     break;
289 
290   case NamespaceAlias:
291     OS << getAsNamespaceAlias()->getName();
292     break;
293 
294   case Global:
295     break;
296 
297   case Super:
298     OS << "__super";
299     break;
300 
301   case TypeSpecWithTemplate:
302     OS << "template ";
303     // Fall through to print the type.
304     LLVM_FALLTHROUGH;
305 
306   case TypeSpec: {
307     const auto *Record =
308             dyn_cast_or_null<ClassTemplateSpecializationDecl>(getAsRecordDecl());
309     if (ResolveTemplateArguments && Record) {
310         // Print the type trait with resolved template parameters.
311         Record->printName(OS);
312         printTemplateArgumentList(OS, Record->getTemplateArgs().asArray(),
313                                   Policy);
314         break;
315     }
316     const Type *T = getAsType();
317 
318     PrintingPolicy InnerPolicy(Policy);
319     InnerPolicy.SuppressScope = true;
320 
321     // Nested-name-specifiers are intended to contain minimally-qualified
322     // types. An actual ElaboratedType will not occur, since we'll store
323     // just the type that is referred to in the nested-name-specifier (e.g.,
324     // a TypedefType, TagType, etc.). However, when we are dealing with
325     // dependent template-id types (e.g., Outer<T>::template Inner<U>),
326     // the type requires its own nested-name-specifier for uniqueness, so we
327     // suppress that nested-name-specifier during printing.
328     assert(!isa<ElaboratedType>(T) &&
329            "Elaborated type in nested-name-specifier");
330     if (const TemplateSpecializationType *SpecType
331           = dyn_cast<TemplateSpecializationType>(T)) {
332       // Print the template name without its corresponding
333       // nested-name-specifier.
334       SpecType->getTemplateName().print(OS, InnerPolicy, true);
335 
336       // Print the template argument list.
337       printTemplateArgumentList(OS, SpecType->template_arguments(),
338                                 InnerPolicy);
339     } else {
340       // Print the type normally
341       QualType(T, 0).print(OS, InnerPolicy);
342     }
343     break;
344   }
345   }
346 
347   OS << "::";
348 }
349 
350 LLVM_DUMP_METHOD void NestedNameSpecifier::dump(const LangOptions &LO) const {
351   dump(llvm::errs(), LO);
352 }
353 
354 LLVM_DUMP_METHOD void NestedNameSpecifier::dump() const { dump(llvm::errs()); }
355 
356 LLVM_DUMP_METHOD void NestedNameSpecifier::dump(llvm::raw_ostream &OS) const {
357   LangOptions LO;
358   dump(OS, LO);
359 }
360 
361 LLVM_DUMP_METHOD void NestedNameSpecifier::dump(llvm::raw_ostream &OS,
362                                                 const LangOptions &LO) const {
363   print(OS, PrintingPolicy(LO));
364 }
365 
366 unsigned
367 NestedNameSpecifierLoc::getLocalDataLength(NestedNameSpecifier *Qualifier) {
368   assert(Qualifier && "Expected a non-NULL qualifier");
369 
370   // Location of the trailing '::'.
371   unsigned Length = sizeof(unsigned);
372 
373   switch (Qualifier->getKind()) {
374   case NestedNameSpecifier::Global:
375     // Nothing more to add.
376     break;
377 
378   case NestedNameSpecifier::Identifier:
379   case NestedNameSpecifier::Namespace:
380   case NestedNameSpecifier::NamespaceAlias:
381   case NestedNameSpecifier::Super:
382     // The location of the identifier or namespace name.
383     Length += sizeof(unsigned);
384     break;
385 
386   case NestedNameSpecifier::TypeSpecWithTemplate:
387   case NestedNameSpecifier::TypeSpec:
388     // The "void*" that points at the TypeLoc data.
389     // Note: the 'template' keyword is part of the TypeLoc.
390     Length += sizeof(void *);
391     break;
392   }
393 
394   return Length;
395 }
396 
397 unsigned
398 NestedNameSpecifierLoc::getDataLength(NestedNameSpecifier *Qualifier) {
399   unsigned Length = 0;
400   for (; Qualifier; Qualifier = Qualifier->getPrefix())
401     Length += getLocalDataLength(Qualifier);
402   return Length;
403 }
404 
405 /// Load a (possibly unaligned) source location from a given address
406 /// and offset.
407 static SourceLocation LoadSourceLocation(void *Data, unsigned Offset) {
408   unsigned Raw;
409   memcpy(&Raw, static_cast<char *>(Data) + Offset, sizeof(unsigned));
410   return SourceLocation::getFromRawEncoding(Raw);
411 }
412 
413 /// Load a (possibly unaligned) pointer from a given address and
414 /// offset.
415 static void *LoadPointer(void *Data, unsigned Offset) {
416   void *Result;
417   memcpy(&Result, static_cast<char *>(Data) + Offset, sizeof(void*));
418   return Result;
419 }
420 
421 SourceRange NestedNameSpecifierLoc::getSourceRange() const {
422   if (!Qualifier)
423     return SourceRange();
424 
425   NestedNameSpecifierLoc First = *this;
426   while (NestedNameSpecifierLoc Prefix = First.getPrefix())
427     First = Prefix;
428 
429   return SourceRange(First.getLocalSourceRange().getBegin(),
430                      getLocalSourceRange().getEnd());
431 }
432 
433 SourceRange NestedNameSpecifierLoc::getLocalSourceRange() const {
434   if (!Qualifier)
435     return SourceRange();
436 
437   unsigned Offset = getDataLength(Qualifier->getPrefix());
438   switch (Qualifier->getKind()) {
439   case NestedNameSpecifier::Global:
440     return LoadSourceLocation(Data, Offset);
441 
442   case NestedNameSpecifier::Identifier:
443   case NestedNameSpecifier::Namespace:
444   case NestedNameSpecifier::NamespaceAlias:
445   case NestedNameSpecifier::Super:
446     return SourceRange(LoadSourceLocation(Data, Offset),
447                        LoadSourceLocation(Data, Offset + sizeof(unsigned)));
448 
449   case NestedNameSpecifier::TypeSpecWithTemplate:
450   case NestedNameSpecifier::TypeSpec: {
451     // The "void*" that points at the TypeLoc data.
452     // Note: the 'template' keyword is part of the TypeLoc.
453     void *TypeData = LoadPointer(Data, Offset);
454     TypeLoc TL(Qualifier->getAsType(), TypeData);
455     return SourceRange(TL.getBeginLoc(),
456                        LoadSourceLocation(Data, Offset + sizeof(void*)));
457   }
458   }
459 
460   llvm_unreachable("Invalid NNS Kind!");
461 }
462 
463 TypeLoc NestedNameSpecifierLoc::getTypeLoc() const {
464   if (Qualifier->getKind() != NestedNameSpecifier::TypeSpec &&
465       Qualifier->getKind() != NestedNameSpecifier::TypeSpecWithTemplate)
466     return TypeLoc();
467 
468   // The "void*" that points at the TypeLoc data.
469   unsigned Offset = getDataLength(Qualifier->getPrefix());
470   void *TypeData = LoadPointer(Data, Offset);
471   return TypeLoc(Qualifier->getAsType(), TypeData);
472 }
473 
474 static void Append(char *Start, char *End, char *&Buffer, unsigned &BufferSize,
475                    unsigned &BufferCapacity) {
476   if (Start == End)
477     return;
478 
479   if (BufferSize + (End - Start) > BufferCapacity) {
480     // Reallocate the buffer.
481     unsigned NewCapacity = std::max(
482         (unsigned)(BufferCapacity ? BufferCapacity * 2 : sizeof(void *) * 2),
483         (unsigned)(BufferSize + (End - Start)));
484     char *NewBuffer = static_cast<char *>(llvm::safe_malloc(NewCapacity));
485     if (BufferCapacity) {
486       memcpy(NewBuffer, Buffer, BufferSize);
487       free(Buffer);
488     }
489     Buffer = NewBuffer;
490     BufferCapacity = NewCapacity;
491   }
492   assert(Buffer && Start && End && End > Start && "Illegal memory buffer copy");
493   memcpy(Buffer + BufferSize, Start, End - Start);
494   BufferSize += End - Start;
495 }
496 
497 /// Save a source location to the given buffer.
498 static void SaveSourceLocation(SourceLocation Loc, char *&Buffer,
499                                unsigned &BufferSize, unsigned &BufferCapacity) {
500   unsigned Raw = Loc.getRawEncoding();
501   Append(reinterpret_cast<char *>(&Raw),
502          reinterpret_cast<char *>(&Raw) + sizeof(unsigned),
503          Buffer, BufferSize, BufferCapacity);
504 }
505 
506 /// Save a pointer to the given buffer.
507 static void SavePointer(void *Ptr, char *&Buffer, unsigned &BufferSize,
508                         unsigned &BufferCapacity) {
509   Append(reinterpret_cast<char *>(&Ptr),
510          reinterpret_cast<char *>(&Ptr) + sizeof(void *),
511          Buffer, BufferSize, BufferCapacity);
512 }
513 
514 NestedNameSpecifierLocBuilder::
515 NestedNameSpecifierLocBuilder(const NestedNameSpecifierLocBuilder &Other)
516     : Representation(Other.Representation) {
517   if (!Other.Buffer)
518     return;
519 
520   if (Other.BufferCapacity == 0) {
521     // Shallow copy is okay.
522     Buffer = Other.Buffer;
523     BufferSize = Other.BufferSize;
524     return;
525   }
526 
527   // Deep copy
528   Append(Other.Buffer, Other.Buffer + Other.BufferSize, Buffer, BufferSize,
529          BufferCapacity);
530 }
531 
532 NestedNameSpecifierLocBuilder &
533 NestedNameSpecifierLocBuilder::
534 operator=(const NestedNameSpecifierLocBuilder &Other) {
535   Representation = Other.Representation;
536 
537   if (Buffer && Other.Buffer && BufferCapacity >= Other.BufferSize) {
538     // Re-use our storage.
539     BufferSize = Other.BufferSize;
540     memcpy(Buffer, Other.Buffer, BufferSize);
541     return *this;
542   }
543 
544   // Free our storage, if we have any.
545   if (BufferCapacity) {
546     free(Buffer);
547     BufferCapacity = 0;
548   }
549 
550   if (!Other.Buffer) {
551     // Empty.
552     Buffer = nullptr;
553     BufferSize = 0;
554     return *this;
555   }
556 
557   if (Other.BufferCapacity == 0) {
558     // Shallow copy is okay.
559     Buffer = Other.Buffer;
560     BufferSize = Other.BufferSize;
561     return *this;
562   }
563 
564   // Deep copy.
565   BufferSize = 0;
566   Append(Other.Buffer, Other.Buffer + Other.BufferSize, Buffer, BufferSize,
567          BufferCapacity);
568   return *this;
569 }
570 
571 void NestedNameSpecifierLocBuilder::Extend(ASTContext &Context,
572                                            SourceLocation TemplateKWLoc,
573                                            TypeLoc TL,
574                                            SourceLocation ColonColonLoc) {
575   Representation = NestedNameSpecifier::Create(Context, Representation,
576                                                TemplateKWLoc.isValid(),
577                                                TL.getTypePtr());
578 
579   // Push source-location info into the buffer.
580   SavePointer(TL.getOpaqueData(), Buffer, BufferSize, BufferCapacity);
581   SaveSourceLocation(ColonColonLoc, Buffer, BufferSize, BufferCapacity);
582 }
583 
584 void NestedNameSpecifierLocBuilder::Extend(ASTContext &Context,
585                                            IdentifierInfo *Identifier,
586                                            SourceLocation IdentifierLoc,
587                                            SourceLocation ColonColonLoc) {
588   Representation = NestedNameSpecifier::Create(Context, Representation,
589                                                Identifier);
590 
591   // Push source-location info into the buffer.
592   SaveSourceLocation(IdentifierLoc, Buffer, BufferSize, BufferCapacity);
593   SaveSourceLocation(ColonColonLoc, Buffer, BufferSize, BufferCapacity);
594 }
595 
596 void NestedNameSpecifierLocBuilder::Extend(ASTContext &Context,
597                                            NamespaceDecl *Namespace,
598                                            SourceLocation NamespaceLoc,
599                                            SourceLocation ColonColonLoc) {
600   Representation = NestedNameSpecifier::Create(Context, Representation,
601                                                Namespace);
602 
603   // Push source-location info into the buffer.
604   SaveSourceLocation(NamespaceLoc, Buffer, BufferSize, BufferCapacity);
605   SaveSourceLocation(ColonColonLoc, Buffer, BufferSize, BufferCapacity);
606 }
607 
608 void NestedNameSpecifierLocBuilder::Extend(ASTContext &Context,
609                                            NamespaceAliasDecl *Alias,
610                                            SourceLocation AliasLoc,
611                                            SourceLocation ColonColonLoc) {
612   Representation = NestedNameSpecifier::Create(Context, Representation, Alias);
613 
614   // Push source-location info into the buffer.
615   SaveSourceLocation(AliasLoc, Buffer, BufferSize, BufferCapacity);
616   SaveSourceLocation(ColonColonLoc, Buffer, BufferSize, BufferCapacity);
617 }
618 
619 void NestedNameSpecifierLocBuilder::MakeGlobal(ASTContext &Context,
620                                                SourceLocation ColonColonLoc) {
621   assert(!Representation && "Already have a nested-name-specifier!?");
622   Representation = NestedNameSpecifier::GlobalSpecifier(Context);
623 
624   // Push source-location info into the buffer.
625   SaveSourceLocation(ColonColonLoc, Buffer, BufferSize, BufferCapacity);
626 }
627 
628 void NestedNameSpecifierLocBuilder::MakeSuper(ASTContext &Context,
629                                               CXXRecordDecl *RD,
630                                               SourceLocation SuperLoc,
631                                               SourceLocation ColonColonLoc) {
632   Representation = NestedNameSpecifier::SuperSpecifier(Context, RD);
633 
634   // Push source-location info into the buffer.
635   SaveSourceLocation(SuperLoc, Buffer, BufferSize, BufferCapacity);
636   SaveSourceLocation(ColonColonLoc, Buffer, BufferSize, BufferCapacity);
637 }
638 
639 void NestedNameSpecifierLocBuilder::MakeTrivial(ASTContext &Context,
640                                                 NestedNameSpecifier *Qualifier,
641                                                 SourceRange R) {
642   Representation = Qualifier;
643 
644   // Construct bogus (but well-formed) source information for the
645   // nested-name-specifier.
646   BufferSize = 0;
647   SmallVector<NestedNameSpecifier *, 4> Stack;
648   for (NestedNameSpecifier *NNS = Qualifier; NNS; NNS = NNS->getPrefix())
649     Stack.push_back(NNS);
650   while (!Stack.empty()) {
651     NestedNameSpecifier *NNS = Stack.pop_back_val();
652     switch (NNS->getKind()) {
653       case NestedNameSpecifier::Identifier:
654       case NestedNameSpecifier::Namespace:
655       case NestedNameSpecifier::NamespaceAlias:
656         SaveSourceLocation(R.getBegin(), Buffer, BufferSize, BufferCapacity);
657         break;
658 
659       case NestedNameSpecifier::TypeSpec:
660       case NestedNameSpecifier::TypeSpecWithTemplate: {
661         TypeSourceInfo *TSInfo
662         = Context.getTrivialTypeSourceInfo(QualType(NNS->getAsType(), 0),
663                                            R.getBegin());
664         SavePointer(TSInfo->getTypeLoc().getOpaqueData(), Buffer, BufferSize,
665                     BufferCapacity);
666         break;
667       }
668 
669       case NestedNameSpecifier::Global:
670       case NestedNameSpecifier::Super:
671         break;
672     }
673 
674     // Save the location of the '::'.
675     SaveSourceLocation(Stack.empty()? R.getEnd() : R.getBegin(),
676                        Buffer, BufferSize, BufferCapacity);
677   }
678 }
679 
680 void NestedNameSpecifierLocBuilder::Adopt(NestedNameSpecifierLoc Other) {
681   if (BufferCapacity)
682     free(Buffer);
683 
684   if (!Other) {
685     Representation = nullptr;
686     BufferSize = 0;
687     return;
688   }
689 
690   // Rather than copying the data (which is wasteful), "adopt" the
691   // pointer (which points into the ASTContext) but set the capacity to zero to
692   // indicate that we don't own it.
693   Representation = Other.getNestedNameSpecifier();
694   Buffer = static_cast<char *>(Other.getOpaqueData());
695   BufferSize = Other.getDataLength();
696   BufferCapacity = 0;
697 }
698 
699 NestedNameSpecifierLoc
700 NestedNameSpecifierLocBuilder::getWithLocInContext(ASTContext &Context) const {
701   if (!Representation)
702     return NestedNameSpecifierLoc();
703 
704   // If we adopted our data pointer from elsewhere in the AST context, there's
705   // no need to copy the memory.
706   if (BufferCapacity == 0)
707     return NestedNameSpecifierLoc(Representation, Buffer);
708 
709   // FIXME: After copying the source-location information, should we free
710   // our (temporary) buffer and adopt the ASTContext-allocated memory?
711   // Doing so would optimize repeated calls to getWithLocInContext().
712   void *Mem = Context.Allocate(BufferSize, alignof(void *));
713   memcpy(Mem, Buffer, BufferSize);
714   return NestedNameSpecifierLoc(Representation, Mem);
715 }
716