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
27 using 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.
36 class 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
IdDeclInfoPoolIdentifierResolver::IdDeclInfoMap::IdDeclInfoPool46 IdDeclInfoPool(IdDeclInfoPool *Next) : Next(Next) {}
47 };
48
49 IdDeclInfoPool *CurPool = nullptr;
50 unsigned int CurIndex = POOL_SIZE;
51
52 public:
53 IdDeclInfoMap() = default;
54
~IdDeclInfoMap()55 ~IdDeclInfoMap() {
56 IdDeclInfoPool *Cur = CurPool;
57 while (IdDeclInfoPool *P = Cur) {
58 Cur = Cur->Next;
59 delete P;
60 }
61 }
62
63 /// Returns the IdDeclInfo associated to the DeclarationName.
64 /// It creates a new IdDeclInfo if one was not created before for this id.
65 IdDeclInfo &operator[](DeclarationName Name);
66 };
67
68 //===----------------------------------------------------------------------===//
69 // IdDeclInfo Implementation
70 //===----------------------------------------------------------------------===//
71
72 /// RemoveDecl - Remove the decl from the scope chain.
73 /// The decl must already be part of the decl chain.
RemoveDecl(NamedDecl * D)74 void IdentifierResolver::IdDeclInfo::RemoveDecl(NamedDecl *D) {
75 for (DeclsTy::iterator I = Decls.end(); I != Decls.begin(); --I) {
76 if (D == *(I-1)) {
77 Decls.erase(I-1);
78 return;
79 }
80 }
81
82 llvm_unreachable("Didn't find this decl on its identifier's chain!");
83 }
84
85 //===----------------------------------------------------------------------===//
86 // IdentifierResolver Implementation
87 //===----------------------------------------------------------------------===//
88
IdentifierResolver(Preprocessor & PP)89 IdentifierResolver::IdentifierResolver(Preprocessor &PP)
90 : LangOpt(PP.getLangOpts()), PP(PP), IdDeclInfos(new IdDeclInfoMap) {}
91
~IdentifierResolver()92 IdentifierResolver::~IdentifierResolver() {
93 delete IdDeclInfos;
94 }
95
96 /// isDeclInScope - If 'Ctx' is a function/method, isDeclInScope returns true
97 /// if 'D' is in Scope 'S', otherwise 'S' is ignored and isDeclInScope returns
98 /// true if 'D' belongs to the given declaration context.
isDeclInScope(Decl * D,DeclContext * Ctx,Scope * S,bool AllowInlineNamespace) const99 bool IdentifierResolver::isDeclInScope(Decl *D, DeclContext *Ctx, Scope *S,
100 bool AllowInlineNamespace) const {
101 Ctx = Ctx->getRedeclContext();
102
103 if (Ctx->isFunctionOrMethod() || (S && S->isFunctionPrototypeScope())) {
104 // Ignore the scopes associated within transparent declaration contexts.
105 while (S->getEntity() && S->getEntity()->isTransparentContext())
106 S = S->getParent();
107
108 if (S->isDeclScope(D))
109 return true;
110 if (LangOpt.CPlusPlus) {
111 // C++ 3.3.2p3:
112 // The name declared in a catch exception-declaration is local to the
113 // handler and shall not be redeclared in the outermost block of the
114 // handler.
115 // C++ 3.3.2p4:
116 // Names declared in the for-init-statement, and in the condition of if,
117 // while, for, and switch statements are local to the if, while, for, or
118 // switch statement (including the controlled statement), and shall not be
119 // redeclared in a subsequent condition of that statement nor in the
120 // outermost block (or, for the if statement, any of the outermost blocks)
121 // of the controlled statement.
122 //
123 assert(S->getParent() && "No TUScope?");
124 if (S->getParent()->getFlags() & Scope::ControlScope) {
125 S = S->getParent();
126 if (S->isDeclScope(D))
127 return true;
128 }
129 if (S->getFlags() & Scope::FnTryCatchScope)
130 return S->getParent()->isDeclScope(D);
131 }
132 return false;
133 }
134
135 // FIXME: If D is a local extern declaration, this check doesn't make sense;
136 // we should be checking its lexical context instead in that case, because
137 // that is its scope.
138 DeclContext *DCtx = D->getDeclContext()->getRedeclContext();
139 return AllowInlineNamespace ? Ctx->InEnclosingNamespaceSetOf(DCtx)
140 : Ctx->Equals(DCtx);
141 }
142
143 /// AddDecl - Link the decl to its shadowed decl chain.
AddDecl(NamedDecl * D)144 void IdentifierResolver::AddDecl(NamedDecl *D) {
145 DeclarationName Name = D->getDeclName();
146 if (IdentifierInfo *II = Name.getAsIdentifierInfo())
147 updatingIdentifier(*II);
148
149 void *Ptr = Name.getFETokenInfo();
150
151 if (!Ptr) {
152 Name.setFETokenInfo(D);
153 return;
154 }
155
156 IdDeclInfo *IDI;
157
158 if (isDeclPtr(Ptr)) {
159 Name.setFETokenInfo(nullptr);
160 IDI = &(*IdDeclInfos)[Name];
161 NamedDecl *PrevD = static_cast<NamedDecl*>(Ptr);
162 IDI->AddDecl(PrevD);
163 } else
164 IDI = toIdDeclInfo(Ptr);
165
166 IDI->AddDecl(D);
167 }
168
InsertDeclAfter(iterator Pos,NamedDecl * D)169 void IdentifierResolver::InsertDeclAfter(iterator Pos, NamedDecl *D) {
170 DeclarationName Name = D->getDeclName();
171 if (IdentifierInfo *II = Name.getAsIdentifierInfo())
172 updatingIdentifier(*II);
173
174 void *Ptr = Name.getFETokenInfo();
175
176 if (!Ptr) {
177 AddDecl(D);
178 return;
179 }
180
181 if (isDeclPtr(Ptr)) {
182 // We only have a single declaration: insert before or after it,
183 // as appropriate.
184 if (Pos == iterator()) {
185 // Add the new declaration before the existing declaration.
186 NamedDecl *PrevD = static_cast<NamedDecl*>(Ptr);
187 RemoveDecl(PrevD);
188 AddDecl(D);
189 AddDecl(PrevD);
190 } else {
191 // Add new declaration after the existing declaration.
192 AddDecl(D);
193 }
194
195 return;
196 }
197
198 // General case: insert the declaration at the appropriate point in the
199 // list, which already has at least two elements.
200 IdDeclInfo *IDI = toIdDeclInfo(Ptr);
201 if (Pos.isIterator()) {
202 IDI->InsertDecl(Pos.getIterator() + 1, D);
203 } else
204 IDI->InsertDecl(IDI->decls_begin(), D);
205 }
206
207 /// RemoveDecl - Unlink the decl from its shadowed decl chain.
208 /// The decl must already be part of the decl chain.
RemoveDecl(NamedDecl * D)209 void IdentifierResolver::RemoveDecl(NamedDecl *D) {
210 assert(D && "null param passed");
211 DeclarationName Name = D->getDeclName();
212 if (IdentifierInfo *II = Name.getAsIdentifierInfo())
213 updatingIdentifier(*II);
214
215 void *Ptr = Name.getFETokenInfo();
216
217 assert(Ptr && "Didn't find this decl on its identifier's chain!");
218
219 if (isDeclPtr(Ptr)) {
220 assert(D == Ptr && "Didn't find this decl on its identifier's chain!");
221 Name.setFETokenInfo(nullptr);
222 return;
223 }
224
225 return toIdDeclInfo(Ptr)->RemoveDecl(D);
226 }
227
228 /// begin - Returns an iterator for decls with name 'Name'.
229 IdentifierResolver::iterator
begin(DeclarationName Name)230 IdentifierResolver::begin(DeclarationName Name) {
231 if (IdentifierInfo *II = Name.getAsIdentifierInfo())
232 readingIdentifier(*II);
233
234 void *Ptr = Name.getFETokenInfo();
235 if (!Ptr) return end();
236
237 if (isDeclPtr(Ptr))
238 return iterator(static_cast<NamedDecl*>(Ptr));
239
240 IdDeclInfo *IDI = toIdDeclInfo(Ptr);
241
242 IdDeclInfo::DeclsTy::iterator I = IDI->decls_end();
243 if (I != IDI->decls_begin())
244 return iterator(I-1);
245 // No decls found.
246 return end();
247 }
248
249 namespace {
250
251 enum DeclMatchKind {
252 DMK_Different,
253 DMK_Replace,
254 DMK_Ignore
255 };
256
257 } // namespace
258
259 /// Compare two declarations to see whether they are different or,
260 /// if they are the same, whether the new declaration should replace the
261 /// existing declaration.
compareDeclarations(NamedDecl * Existing,NamedDecl * New)262 static DeclMatchKind compareDeclarations(NamedDecl *Existing, NamedDecl *New) {
263 // If the declarations are identical, ignore the new one.
264 if (Existing == New)
265 return DMK_Ignore;
266
267 // If the declarations have different kinds, they're obviously different.
268 if (Existing->getKind() != New->getKind())
269 return DMK_Different;
270
271 // If the declarations are redeclarations of each other, keep the newest one.
272 if (Existing->getCanonicalDecl() == New->getCanonicalDecl()) {
273 // If we're adding an imported declaration, don't replace another imported
274 // declaration.
275 if (Existing->isFromASTFile() && New->isFromASTFile())
276 return DMK_Different;
277
278 // If either of these is the most recent declaration, use it.
279 Decl *MostRecent = Existing->getMostRecentDecl();
280 if (Existing == MostRecent)
281 return DMK_Ignore;
282
283 if (New == MostRecent)
284 return DMK_Replace;
285
286 // If the existing declaration is somewhere in the previous declaration
287 // chain of the new declaration, then prefer the new declaration.
288 for (auto RD : New->redecls()) {
289 if (RD == Existing)
290 return DMK_Replace;
291
292 if (RD->isCanonicalDecl())
293 break;
294 }
295
296 return DMK_Ignore;
297 }
298
299 return DMK_Different;
300 }
301
tryAddTopLevelDecl(NamedDecl * D,DeclarationName Name)302 bool IdentifierResolver::tryAddTopLevelDecl(NamedDecl *D, DeclarationName Name){
303 if (IdentifierInfo *II = Name.getAsIdentifierInfo())
304 readingIdentifier(*II);
305
306 void *Ptr = Name.getFETokenInfo();
307
308 if (!Ptr) {
309 Name.setFETokenInfo(D);
310 return true;
311 }
312
313 IdDeclInfo *IDI;
314
315 if (isDeclPtr(Ptr)) {
316 NamedDecl *PrevD = static_cast<NamedDecl*>(Ptr);
317
318 switch (compareDeclarations(PrevD, D)) {
319 case DMK_Different:
320 break;
321
322 case DMK_Ignore:
323 return false;
324
325 case DMK_Replace:
326 Name.setFETokenInfo(D);
327 return true;
328 }
329
330 Name.setFETokenInfo(nullptr);
331 IDI = &(*IdDeclInfos)[Name];
332
333 // If the existing declaration is not visible in translation unit scope,
334 // then add the new top-level declaration first.
335 if (!PrevD->getDeclContext()->getRedeclContext()->isTranslationUnit()) {
336 IDI->AddDecl(D);
337 IDI->AddDecl(PrevD);
338 } else {
339 IDI->AddDecl(PrevD);
340 IDI->AddDecl(D);
341 }
342 return true;
343 }
344
345 IDI = toIdDeclInfo(Ptr);
346
347 // See whether this declaration is identical to any existing declarations.
348 // If not, find the right place to insert it.
349 for (IdDeclInfo::DeclsTy::iterator I = IDI->decls_begin(),
350 IEnd = IDI->decls_end();
351 I != IEnd; ++I) {
352
353 switch (compareDeclarations(*I, D)) {
354 case DMK_Different:
355 break;
356
357 case DMK_Ignore:
358 return false;
359
360 case DMK_Replace:
361 *I = D;
362 return true;
363 }
364
365 if (!(*I)->getDeclContext()->getRedeclContext()->isTranslationUnit()) {
366 // We've found a declaration that is not visible from the translation
367 // unit (it's in an inner scope). Insert our declaration here.
368 IDI->InsertDecl(I, D);
369 return true;
370 }
371 }
372
373 // Add the declaration to the end.
374 IDI->AddDecl(D);
375 return true;
376 }
377
readingIdentifier(IdentifierInfo & II)378 void IdentifierResolver::readingIdentifier(IdentifierInfo &II) {
379 if (II.isOutOfDate())
380 PP.getExternalSource()->updateOutOfDateIdentifier(II);
381 }
382
updatingIdentifier(IdentifierInfo & II)383 void IdentifierResolver::updatingIdentifier(IdentifierInfo &II) {
384 if (II.isOutOfDate())
385 PP.getExternalSource()->updateOutOfDateIdentifier(II);
386
387 if (II.isFromAST())
388 II.setFETokenInfoChangedSinceDeserialization();
389 }
390
391 //===----------------------------------------------------------------------===//
392 // IdDeclInfoMap Implementation
393 //===----------------------------------------------------------------------===//
394
395 /// Returns the IdDeclInfo associated to the DeclarationName.
396 /// It creates a new IdDeclInfo if one was not created before for this id.
397 IdentifierResolver::IdDeclInfo &
operator [](DeclarationName Name)398 IdentifierResolver::IdDeclInfoMap::operator[](DeclarationName Name) {
399 void *Ptr = Name.getFETokenInfo();
400
401 if (Ptr) return *toIdDeclInfo(Ptr);
402
403 if (CurIndex == POOL_SIZE) {
404 CurPool = new IdDeclInfoPool(CurPool);
405 CurIndex = 0;
406 }
407 IdDeclInfo *IDI = &CurPool->Pool[CurIndex];
408 Name.setFETokenInfo(reinterpret_cast<void*>(
409 reinterpret_cast<uintptr_t>(IDI) | 0x1)
410 );
411 ++CurIndex;
412 return *IDI;
413 }
414
incrementSlowCase()415 void IdentifierResolver::iterator::incrementSlowCase() {
416 NamedDecl *D = **this;
417 void *InfoPtr = D->getDeclName().getFETokenInfo();
418 assert(!isDeclPtr(InfoPtr) && "Decl with wrong id ?");
419 IdDeclInfo *Info = toIdDeclInfo(InfoPtr);
420
421 BaseIter I = getIterator();
422 if (I != Info->decls_begin())
423 *this = iterator(I-1);
424 else // No more decls.
425 *this = iterator();
426 }
427