1//===- IdentifierResolver.cpp - Lexical Scope Name lookup -----------------===//
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 implements the IdentifierResolver class, which is used for lexical
10// scoped lookup, based on declaration names.
11//
12//===----------------------------------------------------------------------===//
13
14#include "clang/Sema/IdentifierResolver.h"
15#include "clang/AST/Decl.h"
16#include "clang/AST/DeclBase.h"
17#include "clang/AST/DeclarationName.h"
18#include "clang/Basic/IdentifierTable.h"
19#include "clang/Basic/LangOptions.h"
20#include "clang/Lex/ExternalPreprocessorSource.h"
21#include "clang/Lex/Preprocessor.h"
22#include "clang/Sema/Scope.h"
23#include "llvm/Support/ErrorHandling.h"
24#include <cassert>
25#include <cstdint>
26
27using namespace clang;
28
29//===----------------------------------------------------------------------===//
30// IdDeclInfoMap class
31//===----------------------------------------------------------------------===//
32
33/// IdDeclInfoMap - Associates IdDeclInfos with declaration names.
34/// Allocates 'pools' (vectors of IdDeclInfos) to avoid allocating each
35/// individual IdDeclInfo to heap.
36class IdentifierResolver::IdDeclInfoMap {
37  static const unsigned int POOL_SIZE = 512;
38
39  /// We use our own linked-list implementation because it is sadly
40  /// impossible to add something to a pre-C++0x STL container without
41  /// a completely unnecessary copy.
42  struct IdDeclInfoPool {
43    IdDeclInfoPool *Next;
44    IdDeclInfo Pool[POOL_SIZE];
45
46    IdDeclInfoPool(IdDeclInfoPool *Next) : Next(Next) {}
47  };
48
49  IdDeclInfoPool *CurPool = nullptr;
50  unsigned int CurIndex = POOL_SIZE;
51
52public:
53  IdDeclInfoMap() = default;
54
55  ~IdDeclInfoMap() {
56    IdDeclInfoPool *Cur = CurPool;
57    while (IdDeclInfoPool *P = Cur) {
58      Cur = Cur->Next;
59      delete P;
60    }
61  }
62
63  IdDeclInfoMap(const IdDeclInfoMap &) = delete;
64  IdDeclInfoMap &operator=(const IdDeclInfoMap &) = delete;
65
66  /// Returns the IdDeclInfo associated to the DeclarationName.
67  /// It creates a new IdDeclInfo if one was not created before for this id.
68  IdDeclInfo &operator[](DeclarationName Name);
69};
70
71//===----------------------------------------------------------------------===//
72// IdDeclInfo Implementation
73//===----------------------------------------------------------------------===//
74
75/// RemoveDecl - Remove the decl from the scope chain.
76/// The decl must already be part of the decl chain.
77void IdentifierResolver::IdDeclInfo::RemoveDecl(NamedDecl *D) {
78  for (DeclsTy::iterator I = Decls.end(); I != Decls.begin(); --I) {
79    if (D == *(I-1)) {
80      Decls.erase(I-1);
81      return;
82    }
83  }
84
85  llvm_unreachable("Didn't find this decl on its identifier's chain!");
86}
87
88//===----------------------------------------------------------------------===//
89// IdentifierResolver Implementation
90//===----------------------------------------------------------------------===//
91
92IdentifierResolver::IdentifierResolver(Preprocessor &PP)
93    : LangOpt(PP.getLangOpts()), PP(PP), IdDeclInfos(new IdDeclInfoMap) {}
94
95IdentifierResolver::~IdentifierResolver() {
96  delete IdDeclInfos;
97}
98
99/// isDeclInScope - If 'Ctx' is a function/method, isDeclInScope returns true
100/// if 'D' is in Scope 'S', otherwise 'S' is ignored and isDeclInScope returns
101/// true if 'D' belongs to the given declaration context.
102bool IdentifierResolver::isDeclInScope(Decl *D, DeclContext *Ctx, Scope *S,
103                                       bool AllowInlineNamespace) const {
104  Ctx = Ctx->getRedeclContext();
105  // The names for HLSL cbuffer/tbuffers only used by the CPU-side
106  // reflection API which supports querying bindings. It will not have name
107  // conflict with other Decls.
108  if (LangOpt.HLSL && isa<HLSLBufferDecl>(D))
109    return false;
110  if (Ctx->isFunctionOrMethod() || (S && S->isFunctionPrototypeScope())) {
111    // Ignore the scopes associated within transparent declaration contexts.
112    while (S->getEntity() &&
113           (S->getEntity()->isTransparentContext() ||
114            (!LangOpt.CPlusPlus && isa<RecordDecl>(S->getEntity()))))
115      S = S->getParent();
116
117    if (S->isDeclScope(D))
118      return true;
119    if (LangOpt.CPlusPlus) {
120      // C++ 3.3.2p3:
121      // The name declared in a catch exception-declaration is local to the
122      // handler and shall not be redeclared in the outermost block of the
123      // handler.
124      // C++ 3.3.2p4:
125      // Names declared in the for-init-statement, and in the condition of if,
126      // while, for, and switch statements are local to the if, while, for, or
127      // switch statement (including the controlled statement), and shall not be
128      // redeclared in a subsequent condition of that statement nor in the
129      // outermost block (or, for the if statement, any of the outermost blocks)
130      // of the controlled statement.
131      //
132      assert(S->getParent() && "No TUScope?");
133      // If the current decl is in a lambda, we shouldn't consider this is a
134      // redefinition as lambda has its own scope.
135      if (S->getParent()->isControlScope() && !S->isFunctionScope()) {
136        S = S->getParent();
137        if (S->isDeclScope(D))
138          return true;
139      }
140      if (S->isFnTryCatchScope())
141        return S->getParent()->isDeclScope(D);
142    }
143    return false;
144  }
145
146  // FIXME: If D is a local extern declaration, this check doesn't make sense;
147  // we should be checking its lexical context instead in that case, because
148  // that is its scope.
149  DeclContext *DCtx = D->getDeclContext()->getRedeclContext();
150  return AllowInlineNamespace ? Ctx->InEnclosingNamespaceSetOf(DCtx)
151                              : Ctx->Equals(DCtx);
152}
153
154/// AddDecl - Link the decl to its shadowed decl chain.
155void IdentifierResolver::AddDecl(NamedDecl *D) {
156  DeclarationName Name = D->getDeclName();
157  if (IdentifierInfo *II = Name.getAsIdentifierInfo())
158    updatingIdentifier(*II);
159
160  void *Ptr = Name.getFETokenInfo();
161
162  if (!Ptr) {
163    Name.setFETokenInfo(D);
164    return;
165  }
166
167  IdDeclInfo *IDI;
168
169  if (isDeclPtr(Ptr)) {
170    Name.setFETokenInfo(nullptr);
171    IDI = &(*IdDeclInfos)[Name];
172    NamedDecl *PrevD = static_cast<NamedDecl*>(Ptr);
173    IDI->AddDecl(PrevD);
174  } else
175    IDI = toIdDeclInfo(Ptr);
176
177  IDI->AddDecl(D);
178}
179
180void IdentifierResolver::InsertDeclAfter(iterator Pos, NamedDecl *D) {
181  DeclarationName Name = D->getDeclName();
182  if (IdentifierInfo *II = Name.getAsIdentifierInfo())
183    updatingIdentifier(*II);
184
185  void *Ptr = Name.getFETokenInfo();
186
187  if (!Ptr) {
188    AddDecl(D);
189    return;
190  }
191
192  if (isDeclPtr(Ptr)) {
193    // We only have a single declaration: insert before or after it,
194    // as appropriate.
195    if (Pos == iterator()) {
196      // Add the new declaration before the existing declaration.
197      NamedDecl *PrevD = static_cast<NamedDecl*>(Ptr);
198      RemoveDecl(PrevD);
199      AddDecl(D);
200      AddDecl(PrevD);
201    } else {
202      // Add new declaration after the existing declaration.
203      AddDecl(D);
204    }
205
206    return;
207  }
208
209  // General case: insert the declaration at the appropriate point in the
210  // list, which already has at least two elements.
211  IdDeclInfo *IDI = toIdDeclInfo(Ptr);
212  if (Pos.isIterator()) {
213    IDI->InsertDecl(Pos.getIterator() + 1, D);
214  } else
215    IDI->InsertDecl(IDI->decls_begin(), D);
216}
217
218/// RemoveDecl - Unlink the decl from its shadowed decl chain.
219/// The decl must already be part of the decl chain.
220void IdentifierResolver::RemoveDecl(NamedDecl *D) {
221  assert(D && "null param passed");
222  DeclarationName Name = D->getDeclName();
223  if (IdentifierInfo *II = Name.getAsIdentifierInfo())
224    updatingIdentifier(*II);
225
226  void *Ptr = Name.getFETokenInfo();
227
228  assert(Ptr && "Didn't find this decl on its identifier's chain!");
229
230  if (isDeclPtr(Ptr)) {
231    assert(D == Ptr && "Didn't find this decl on its identifier's chain!");
232    Name.setFETokenInfo(nullptr);
233    return;
234  }
235
236  return toIdDeclInfo(Ptr)->RemoveDecl(D);
237}
238
239llvm::iterator_range<IdentifierResolver::iterator>
240IdentifierResolver::decls(DeclarationName Name) {
241  return {begin(Name), end()};
242}
243
244IdentifierResolver::iterator IdentifierResolver::begin(DeclarationName Name) {
245  if (IdentifierInfo *II = Name.getAsIdentifierInfo())
246    readingIdentifier(*II);
247
248  void *Ptr = Name.getFETokenInfo();
249  if (!Ptr) return end();
250
251  if (isDeclPtr(Ptr))
252    return iterator(static_cast<NamedDecl*>(Ptr));
253
254  IdDeclInfo *IDI = toIdDeclInfo(Ptr);
255
256  IdDeclInfo::DeclsTy::iterator I = IDI->decls_end();
257  if (I != IDI->decls_begin())
258    return iterator(I-1);
259  // No decls found.
260  return end();
261}
262
263namespace {
264
265enum DeclMatchKind {
266  DMK_Different,
267  DMK_Replace,
268  DMK_Ignore
269};
270
271} // namespace
272
273/// Compare two declarations to see whether they are different or,
274/// if they are the same, whether the new declaration should replace the
275/// existing declaration.
276static DeclMatchKind compareDeclarations(NamedDecl *Existing, NamedDecl *New) {
277  // If the declarations are identical, ignore the new one.
278  if (Existing == New)
279    return DMK_Ignore;
280
281  // If the declarations have different kinds, they're obviously different.
282  if (Existing->getKind() != New->getKind())
283    return DMK_Different;
284
285  // If the declarations are redeclarations of each other, keep the newest one.
286  if (Existing->getCanonicalDecl() == New->getCanonicalDecl()) {
287    // If we're adding an imported declaration, don't replace another imported
288    // declaration.
289    if (Existing->isFromASTFile() && New->isFromASTFile())
290      return DMK_Different;
291
292    // If either of these is the most recent declaration, use it.
293    Decl *MostRecent = Existing->getMostRecentDecl();
294    if (Existing == MostRecent)
295      return DMK_Ignore;
296
297    if (New == MostRecent)
298      return DMK_Replace;
299
300    // If the existing declaration is somewhere in the previous declaration
301    // chain of the new declaration, then prefer the new declaration.
302    for (auto *RD : New->redecls()) {
303      if (RD == Existing)
304        return DMK_Replace;
305
306      if (RD->isCanonicalDecl())
307        break;
308    }
309
310    return DMK_Ignore;
311  }
312
313  return DMK_Different;
314}
315
316bool IdentifierResolver::tryAddTopLevelDecl(NamedDecl *D, DeclarationName Name){
317  if (IdentifierInfo *II = Name.getAsIdentifierInfo())
318    readingIdentifier(*II);
319
320  void *Ptr = Name.getFETokenInfo();
321
322  if (!Ptr) {
323    Name.setFETokenInfo(D);
324    return true;
325  }
326
327  IdDeclInfo *IDI;
328
329  if (isDeclPtr(Ptr)) {
330    NamedDecl *PrevD = static_cast<NamedDecl*>(Ptr);
331
332    switch (compareDeclarations(PrevD, D)) {
333    case DMK_Different:
334      break;
335
336    case DMK_Ignore:
337      return false;
338
339    case DMK_Replace:
340      Name.setFETokenInfo(D);
341      return true;
342    }
343
344    Name.setFETokenInfo(nullptr);
345    IDI = &(*IdDeclInfos)[Name];
346
347    // If the existing declaration is not visible in translation unit scope,
348    // then add the new top-level declaration first.
349    if (!PrevD->getDeclContext()->getRedeclContext()->isTranslationUnit()) {
350      IDI->AddDecl(D);
351      IDI->AddDecl(PrevD);
352    } else {
353      IDI->AddDecl(PrevD);
354      IDI->AddDecl(D);
355    }
356    return true;
357  }
358
359  IDI = toIdDeclInfo(Ptr);
360
361  // See whether this declaration is identical to any existing declarations.
362  // If not, find the right place to insert it.
363  for (IdDeclInfo::DeclsTy::iterator I = IDI->decls_begin(),
364                                  IEnd = IDI->decls_end();
365       I != IEnd; ++I) {
366
367    switch (compareDeclarations(*I, D)) {
368    case DMK_Different:
369      break;
370
371    case DMK_Ignore:
372      return false;
373
374    case DMK_Replace:
375      *I = D;
376      return true;
377    }
378
379    if (!(*I)->getDeclContext()->getRedeclContext()->isTranslationUnit()) {
380      // We've found a declaration that is not visible from the translation
381      // unit (it's in an inner scope). Insert our declaration here.
382      IDI->InsertDecl(I, D);
383      return true;
384    }
385  }
386
387  // Add the declaration to the end.
388  IDI->AddDecl(D);
389  return true;
390}
391
392void IdentifierResolver::readingIdentifier(IdentifierInfo &II) {
393  if (II.isOutOfDate())
394    PP.getExternalSource()->updateOutOfDateIdentifier(II);
395}
396
397void IdentifierResolver::updatingIdentifier(IdentifierInfo &II) {
398  if (II.isOutOfDate())
399    PP.getExternalSource()->updateOutOfDateIdentifier(II);
400
401  if (II.isFromAST())
402    II.setFETokenInfoChangedSinceDeserialization();
403}
404
405//===----------------------------------------------------------------------===//
406// IdDeclInfoMap Implementation
407//===----------------------------------------------------------------------===//
408
409/// Returns the IdDeclInfo associated to the DeclarationName.
410/// It creates a new IdDeclInfo if one was not created before for this id.
411IdentifierResolver::IdDeclInfo &
412IdentifierResolver::IdDeclInfoMap::operator[](DeclarationName Name) {
413  void *Ptr = Name.getFETokenInfo();
414
415  if (Ptr) return *toIdDeclInfo(Ptr);
416
417  if (CurIndex == POOL_SIZE) {
418    CurPool = new IdDeclInfoPool(CurPool);
419    CurIndex = 0;
420  }
421  IdDeclInfo *IDI = &CurPool->Pool[CurIndex];
422  Name.setFETokenInfo(reinterpret_cast<void*>(
423                              reinterpret_cast<uintptr_t>(IDI) | 0x1)
424                                                                     );
425  ++CurIndex;
426  return *IDI;
427}
428
429void IdentifierResolver::iterator::incrementSlowCase() {
430  NamedDecl *D = **this;
431  void *InfoPtr = D->getDeclName().getFETokenInfo();
432  assert(!isDeclPtr(InfoPtr) && "Decl with wrong id ?");
433  IdDeclInfo *Info = toIdDeclInfo(InfoPtr);
434
435  BaseIter I = getIterator();
436  if (I != Info->decls_begin())
437    *this = iterator(I-1);
438  else // No more decls.
439    *this = iterator();
440}
441