clang/lib/Sema/IdentifierResolver.cpp

   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
  46     IdDeclInfoPool(IdDeclInfoPool *Next) : Next(Next) {}
  47   };
  48
  49   IdDeclInfoPool *CurPool = nullptr;
  50   unsigned int CurIndex = POOL_SIZE;
  51
  52 public:
  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.
  77 void 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
  92 IdentifierResolver::IdentifierResolver(Preprocessor &PP)
  93     : LangOpt(PP.getLangOpts()), PP(PP), IdDeclInfos(new IdDeclInfoMap) {}
  94
  95 IdentifierResolver::~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.
 102 bool 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.
 155 void 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
 180 void 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.
 220 void 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
 239 llvm::iterator_range<IdentifierResolver::iterator>
 240 IdentifierResolver::decls(DeclarationName Name) {
 241   return {begin(Name), end()};
 242 }
 243
 244 IdentifierResolver::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
 263 namespace {
 264
 265 enum 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.
 276 static 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
 316 bool 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
 392 void IdentifierResolver::readingIdentifier(IdentifierInfo &II) {
 393   if (II.isOutOfDate())
 394     PP.getExternalSource()->updateOutOfDateIdentifier(II);
 395 }
 396
 397 void 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.
 411 IdentifierResolver::IdDeclInfo &
 412 IdentifierResolver::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
 429 void 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 }