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() && S->getEntity()->isTransparentContext())
 113       S = S->getParent();
 114
 115     if (S->isDeclScope(D))
 116       return true;
 117     if (LangOpt.CPlusPlus) {
 118       // C++ 3.3.2p3:
 119       // The name declared in a catch exception-declaration is local to the
 120       // handler and shall not be redeclared in the outermost block of the
 121       // handler.
 122       // C++ 3.3.2p4:
 123       // Names declared in the for-init-statement, and in the condition of if,
 124       // while, for, and switch statements are local to the if, while, for, or
 125       // switch statement (including the controlled statement), and shall not be
 126       // redeclared in a subsequent condition of that statement nor in the
 127       // outermost block (or, for the if statement, any of the outermost blocks)
 128       // of the controlled statement.
 129       //
 130       assert(S->getParent() && "No TUScope?");
 131       // If the current decl is in a lambda, we shouldn't consider this is a
 132       // redefinition as lambda has its own scope.
 133       if (S->getParent()->isControlScope() && !S->isFunctionScope()) {
 134         S = S->getParent();
 135         if (S->isDeclScope(D))
 136           return true;
 137       }
 138       if (S->isFnTryCatchScope())
 139         return S->getParent()->isDeclScope(D);
 140     }
 141     return false;
 142   }
 143
 144   // FIXME: If D is a local extern declaration, this check doesn't make sense;
 145   // we should be checking its lexical context instead in that case, because
 146   // that is its scope.
 147   DeclContext *DCtx = D->getDeclContext()->getRedeclContext();
 148   return AllowInlineNamespace ? Ctx->InEnclosingNamespaceSetOf(DCtx)
 149                               : Ctx->Equals(DCtx);
 150 }
 151
 152 /// AddDecl - Link the decl to its shadowed decl chain.
 153 void IdentifierResolver::AddDecl(NamedDecl *D) {
 154   DeclarationName Name = D->getDeclName();
 155   if (IdentifierInfo *II = Name.getAsIdentifierInfo())
 156     updatingIdentifier(*II);
 157
 158   void *Ptr = Name.getFETokenInfo();
 159
 160   if (!Ptr) {
 161     Name.setFETokenInfo(D);
 162     return;
 163   }
 164
 165   IdDeclInfo *IDI;
 166
 167   if (isDeclPtr(Ptr)) {
 168     Name.setFETokenInfo(nullptr);
 169     IDI = &(*IdDeclInfos)[Name];
 170     NamedDecl *PrevD = static_cast<NamedDecl*>(Ptr);
 171     IDI->AddDecl(PrevD);
 172   } else
 173     IDI = toIdDeclInfo(Ptr);
 174
 175   IDI->AddDecl(D);
 176 }
 177
 178 void IdentifierResolver::InsertDeclAfter(iterator Pos, NamedDecl *D) {
 179   DeclarationName Name = D->getDeclName();
 180   if (IdentifierInfo *II = Name.getAsIdentifierInfo())
 181     updatingIdentifier(*II);
 182
 183   void *Ptr = Name.getFETokenInfo();
 184
 185   if (!Ptr) {
 186     AddDecl(D);
 187     return;
 188   }
 189
 190   if (isDeclPtr(Ptr)) {
 191     // We only have a single declaration: insert before or after it,
 192     // as appropriate.
 193     if (Pos == iterator()) {
 194       // Add the new declaration before the existing declaration.
 195       NamedDecl *PrevD = static_cast<NamedDecl*>(Ptr);
 196       RemoveDecl(PrevD);
 197       AddDecl(D);
 198       AddDecl(PrevD);
 199     } else {
 200       // Add new declaration after the existing declaration.
 201       AddDecl(D);
 202     }
 203
 204     return;
 205   }
 206
 207   // General case: insert the declaration at the appropriate point in the
 208   // list, which already has at least two elements.
 209   IdDeclInfo *IDI = toIdDeclInfo(Ptr);
 210   if (Pos.isIterator()) {
 211     IDI->InsertDecl(Pos.getIterator() + 1, D);
 212   } else
 213     IDI->InsertDecl(IDI->decls_begin(), D);
 214 }
 215
 216 /// RemoveDecl - Unlink the decl from its shadowed decl chain.
 217 /// The decl must already be part of the decl chain.
 218 void IdentifierResolver::RemoveDecl(NamedDecl *D) {
 219   assert(D && "null param passed");
 220   DeclarationName Name = D->getDeclName();
 221   if (IdentifierInfo *II = Name.getAsIdentifierInfo())
 222     updatingIdentifier(*II);
 223
 224   void *Ptr = Name.getFETokenInfo();
 225
 226   assert(Ptr && "Didn't find this decl on its identifier's chain!");
 227
 228   if (isDeclPtr(Ptr)) {
 229     assert(D == Ptr && "Didn't find this decl on its identifier's chain!");
 230     Name.setFETokenInfo(nullptr);
 231     return;
 232   }
 233
 234   return toIdDeclInfo(Ptr)->RemoveDecl(D);
 235 }
 236
 237 llvm::iterator_range<IdentifierResolver::iterator>
 238 IdentifierResolver::decls(DeclarationName Name) {
 239   return {begin(Name), end()};
 240 }
 241
 242 IdentifierResolver::iterator IdentifierResolver::begin(DeclarationName Name) {
 243   if (IdentifierInfo *II = Name.getAsIdentifierInfo())
 244     readingIdentifier(*II);
 245
 246   void *Ptr = Name.getFETokenInfo();
 247   if (!Ptr) return end();
 248
 249   if (isDeclPtr(Ptr))
 250     return iterator(static_cast<NamedDecl*>(Ptr));
 251
 252   IdDeclInfo *IDI = toIdDeclInfo(Ptr);
 253
 254   IdDeclInfo::DeclsTy::iterator I = IDI->decls_end();
 255   if (I != IDI->decls_begin())
 256     return iterator(I-1);
 257   // No decls found.
 258   return end();
 259 }
 260
 261 namespace {
 262
 263 enum DeclMatchKind {
 264   DMK_Different,
 265   DMK_Replace,
 266   DMK_Ignore
 267 };
 268
 269 } // namespace
 270
 271 /// Compare two declarations to see whether they are different or,
 272 /// if they are the same, whether the new declaration should replace the
 273 /// existing declaration.
 274 static DeclMatchKind compareDeclarations(NamedDecl *Existing, NamedDecl *New) {
 275   // If the declarations are identical, ignore the new one.
 276   if (Existing == New)
 277     return DMK_Ignore;
 278
 279   // If the declarations have different kinds, they're obviously different.
 280   if (Existing->getKind() != New->getKind())
 281     return DMK_Different;
 282
 283   // If the declarations are redeclarations of each other, keep the newest one.
 284   if (Existing->getCanonicalDecl() == New->getCanonicalDecl()) {
 285     // If we're adding an imported declaration, don't replace another imported
 286     // declaration.
 287     if (Existing->isFromASTFile() && New->isFromASTFile())
 288       return DMK_Different;
 289
 290     // If either of these is the most recent declaration, use it.
 291     Decl *MostRecent = Existing->getMostRecentDecl();
 292     if (Existing == MostRecent)
 293       return DMK_Ignore;
 294
 295     if (New == MostRecent)
 296       return DMK_Replace;
 297
 298     // If the existing declaration is somewhere in the previous declaration
 299     // chain of the new declaration, then prefer the new declaration.
 300     for (auto *RD : New->redecls()) {
 301       if (RD == Existing)
 302         return DMK_Replace;
 303
 304       if (RD->isCanonicalDecl())
 305         break;
 306     }
 307
 308     return DMK_Ignore;
 309   }
 310
 311   return DMK_Different;
 312 }
 313
 314 bool IdentifierResolver::tryAddTopLevelDecl(NamedDecl *D, DeclarationName Name){
 315   if (IdentifierInfo *II = Name.getAsIdentifierInfo())
 316     readingIdentifier(*II);
 317
 318   void *Ptr = Name.getFETokenInfo();
 319
 320   if (!Ptr) {
 321     Name.setFETokenInfo(D);
 322     return true;
 323   }
 324
 325   IdDeclInfo *IDI;
 326
 327   if (isDeclPtr(Ptr)) {
 328     NamedDecl *PrevD = static_cast<NamedDecl*>(Ptr);
 329
 330     switch (compareDeclarations(PrevD, D)) {
 331     case DMK_Different:
 332       break;
 333
 334     case DMK_Ignore:
 335       return false;
 336
 337     case DMK_Replace:
 338       Name.setFETokenInfo(D);
 339       return true;
 340     }
 341
 342     Name.setFETokenInfo(nullptr);
 343     IDI = &(*IdDeclInfos)[Name];
 344
 345     // If the existing declaration is not visible in translation unit scope,
 346     // then add the new top-level declaration first.
 347     if (!PrevD->getDeclContext()->getRedeclContext()->isTranslationUnit()) {
 348       IDI->AddDecl(D);
 349       IDI->AddDecl(PrevD);
 350     } else {
 351       IDI->AddDecl(PrevD);
 352       IDI->AddDecl(D);
 353     }
 354     return true;
 355   }
 356
 357   IDI = toIdDeclInfo(Ptr);
 358
 359   // See whether this declaration is identical to any existing declarations.
 360   // If not, find the right place to insert it.
 361   for (IdDeclInfo::DeclsTy::iterator I = IDI->decls_begin(),
 362                                   IEnd = IDI->decls_end();
 363        I != IEnd; ++I) {
 364
 365     switch (compareDeclarations(*I, D)) {
 366     case DMK_Different:
 367       break;
 368
 369     case DMK_Ignore:
 370       return false;
 371
 372     case DMK_Replace:
 373       *I = D;
 374       return true;
 375     }
 376
 377     if (!(*I)->getDeclContext()->getRedeclContext()->isTranslationUnit()) {
 378       // We've found a declaration that is not visible from the translation
 379       // unit (it's in an inner scope). Insert our declaration here.
 380       IDI->InsertDecl(I, D);
 381       return true;
 382     }
 383   }
 384
 385   // Add the declaration to the end.
 386   IDI->AddDecl(D);
 387   return true;
 388 }
 389
 390 void IdentifierResolver::readingIdentifier(IdentifierInfo &II) {
 391   if (II.isOutOfDate())
 392     PP.getExternalSource()->updateOutOfDateIdentifier(II);
 393 }
 394
 395 void IdentifierResolver::updatingIdentifier(IdentifierInfo &II) {
 396   if (II.isOutOfDate())
 397     PP.getExternalSource()->updateOutOfDateIdentifier(II);
 398
 399   if (II.isFromAST())
 400     II.setFETokenInfoChangedSinceDeserialization();
 401 }
 402
 403 //===----------------------------------------------------------------------===//
 404 // IdDeclInfoMap Implementation
 405 //===----------------------------------------------------------------------===//
 406
 407 /// Returns the IdDeclInfo associated to the DeclarationName.
 408 /// It creates a new IdDeclInfo if one was not created before for this id.
 409 IdentifierResolver::IdDeclInfo &
 410 IdentifierResolver::IdDeclInfoMap::operator[](DeclarationName Name) {
 411   void *Ptr = Name.getFETokenInfo();
 412
 413   if (Ptr) return *toIdDeclInfo(Ptr);
 414
 415   if (CurIndex == POOL_SIZE) {
 416     CurPool = new IdDeclInfoPool(CurPool);
 417     CurIndex = 0;
 418   }
 419   IdDeclInfo *IDI = &CurPool->Pool[CurIndex];
 420   Name.setFETokenInfo(reinterpret_cast<void*>(
 421                               reinterpret_cast<uintptr_t>(IDI) | 0x1)
 422                                                                      );
 423   ++CurIndex;
 424   return *IDI;
 425 }
 426
 427 void IdentifierResolver::iterator::incrementSlowCase() {
 428   NamedDecl *D = **this;
 429   void *InfoPtr = D->getDeclName().getFETokenInfo();
 430   assert(!isDeclPtr(InfoPtr) && "Decl with wrong id ?");
 431   IdDeclInfo *Info = toIdDeclInfo(InfoPtr);
 432
 433   BaseIter I = getIterator();
 434   if (I != Info->decls_begin())
 435     *this = iterator(I-1);
 436   else // No more decls.
 437     *this = iterator();
 438 }