SemaCXXScopeSpec.cpp revision 199482
1//===--- SemaCXXScopeSpec.cpp - Semantic Analysis for C++ scope specifiers-===// 2// 3// The LLVM Compiler Infrastructure 4// 5// This file is distributed under the University of Illinois Open Source 6// License. See LICENSE.TXT for details. 7// 8//===----------------------------------------------------------------------===// 9// 10// This file implements C++ semantic analysis for scope specifiers. 11// 12//===----------------------------------------------------------------------===// 13 14#include "Sema.h" 15#include "Lookup.h" 16#include "clang/AST/ASTContext.h" 17#include "clang/AST/DeclTemplate.h" 18#include "clang/AST/ExprCXX.h" 19#include "clang/AST/NestedNameSpecifier.h" 20#include "clang/Basic/PartialDiagnostic.h" 21#include "clang/Parse/DeclSpec.h" 22#include "llvm/ADT/STLExtras.h" 23#include "llvm/Support/raw_ostream.h" 24using namespace clang; 25 26/// \brief Find the current instantiation that associated with the given type. 27static CXXRecordDecl * 28getCurrentInstantiationOf(ASTContext &Context, DeclContext *CurContext, 29 QualType T) { 30 if (T.isNull()) 31 return 0; 32 33 T = Context.getCanonicalType(T); 34 35 for (DeclContext *Ctx = CurContext; Ctx; Ctx = Ctx->getParent()) { 36 // If we've hit a namespace or the global scope, then the 37 // nested-name-specifier can't refer to the current instantiation. 38 if (Ctx->isFileContext()) 39 return 0; 40 41 // Skip non-class contexts. 42 CXXRecordDecl *Record = dyn_cast<CXXRecordDecl>(Ctx); 43 if (!Record) 44 continue; 45 46 // If this record type is not dependent, 47 if (!Record->isDependentType()) 48 return 0; 49 50 // C++ [temp.dep.type]p1: 51 // 52 // In the definition of a class template, a nested class of a 53 // class template, a member of a class template, or a member of a 54 // nested class of a class template, a name refers to the current 55 // instantiation if it is 56 // -- the injected-class-name (9) of the class template or 57 // nested class, 58 // -- in the definition of a primary class template, the name 59 // of the class template followed by the template argument 60 // list of the primary template (as described below) 61 // enclosed in <>, 62 // -- in the definition of a nested class of a class template, 63 // the name of the nested class referenced as a member of 64 // the current instantiation, or 65 // -- in the definition of a partial specialization, the name 66 // of the class template followed by the template argument 67 // list of the partial specialization enclosed in <>. If 68 // the nth template parameter is a parameter pack, the nth 69 // template argument is a pack expansion (14.6.3) whose 70 // pattern is the name of the parameter pack. 71 // (FIXME: parameter packs) 72 // 73 // All of these options come down to having the 74 // nested-name-specifier type that is equivalent to the 75 // injected-class-name of one of the types that is currently in 76 // our context. 77 if (Context.getCanonicalType(Context.getTypeDeclType(Record)) == T) 78 return Record; 79 80 if (ClassTemplateDecl *Template = Record->getDescribedClassTemplate()) { 81 QualType InjectedClassName 82 = Template->getInjectedClassNameType(Context); 83 if (T == Context.getCanonicalType(InjectedClassName)) 84 return Template->getTemplatedDecl(); 85 } 86 // FIXME: check for class template partial specializations 87 } 88 89 return 0; 90} 91 92/// \brief Compute the DeclContext that is associated with the given type. 93/// 94/// \param T the type for which we are attempting to find a DeclContext. 95/// 96/// \returns the declaration context represented by the type T, 97/// or NULL if the declaration context cannot be computed (e.g., because it is 98/// dependent and not the current instantiation). 99DeclContext *Sema::computeDeclContext(QualType T) { 100 if (const TagType *Tag = T->getAs<TagType>()) 101 return Tag->getDecl(); 102 103 return ::getCurrentInstantiationOf(Context, CurContext, T); 104} 105 106/// \brief Compute the DeclContext that is associated with the given 107/// scope specifier. 108/// 109/// \param SS the C++ scope specifier as it appears in the source 110/// 111/// \param EnteringContext when true, we will be entering the context of 112/// this scope specifier, so we can retrieve the declaration context of a 113/// class template or class template partial specialization even if it is 114/// not the current instantiation. 115/// 116/// \returns the declaration context represented by the scope specifier @p SS, 117/// or NULL if the declaration context cannot be computed (e.g., because it is 118/// dependent and not the current instantiation). 119DeclContext *Sema::computeDeclContext(const CXXScopeSpec &SS, 120 bool EnteringContext) { 121 if (!SS.isSet() || SS.isInvalid()) 122 return 0; 123 124 NestedNameSpecifier *NNS 125 = static_cast<NestedNameSpecifier *>(SS.getScopeRep()); 126 if (NNS->isDependent()) { 127 // If this nested-name-specifier refers to the current 128 // instantiation, return its DeclContext. 129 if (CXXRecordDecl *Record = getCurrentInstantiationOf(NNS)) 130 return Record; 131 132 if (EnteringContext) { 133 if (const TemplateSpecializationType *SpecType 134 = dyn_cast_or_null<TemplateSpecializationType>(NNS->getAsType())) { 135 // We are entering the context of the nested name specifier, so try to 136 // match the nested name specifier to either a primary class template 137 // or a class template partial specialization. 138 if (ClassTemplateDecl *ClassTemplate 139 = dyn_cast_or_null<ClassTemplateDecl>( 140 SpecType->getTemplateName().getAsTemplateDecl())) { 141 QualType ContextType 142 = Context.getCanonicalType(QualType(SpecType, 0)); 143 144 // If the type of the nested name specifier is the same as the 145 // injected class name of the named class template, we're entering 146 // into that class template definition. 147 QualType Injected = ClassTemplate->getInjectedClassNameType(Context); 148 if (Context.hasSameType(Injected, ContextType)) 149 return ClassTemplate->getTemplatedDecl(); 150 151 // If the type of the nested name specifier is the same as the 152 // type of one of the class template's class template partial 153 // specializations, we're entering into the definition of that 154 // class template partial specialization. 155 if (ClassTemplatePartialSpecializationDecl *PartialSpec 156 = ClassTemplate->findPartialSpecialization(ContextType)) 157 return PartialSpec; 158 } 159 } else if (const RecordType *RecordT 160 = dyn_cast_or_null<RecordType>(NNS->getAsType())) { 161 // The nested name specifier refers to a member of a class template. 162 return RecordT->getDecl(); 163 } 164 } 165 166 return 0; 167 } 168 169 switch (NNS->getKind()) { 170 case NestedNameSpecifier::Identifier: 171 assert(false && "Dependent nested-name-specifier has no DeclContext"); 172 break; 173 174 case NestedNameSpecifier::Namespace: 175 return NNS->getAsNamespace(); 176 177 case NestedNameSpecifier::TypeSpec: 178 case NestedNameSpecifier::TypeSpecWithTemplate: { 179 const TagType *Tag = NNS->getAsType()->getAs<TagType>(); 180 assert(Tag && "Non-tag type in nested-name-specifier"); 181 return Tag->getDecl(); 182 } break; 183 184 case NestedNameSpecifier::Global: 185 return Context.getTranslationUnitDecl(); 186 } 187 188 // Required to silence a GCC warning. 189 return 0; 190} 191 192bool Sema::isDependentScopeSpecifier(const CXXScopeSpec &SS) { 193 if (!SS.isSet() || SS.isInvalid()) 194 return false; 195 196 NestedNameSpecifier *NNS 197 = static_cast<NestedNameSpecifier *>(SS.getScopeRep()); 198 return NNS->isDependent(); 199} 200 201// \brief Determine whether this C++ scope specifier refers to an 202// unknown specialization, i.e., a dependent type that is not the 203// current instantiation. 204bool Sema::isUnknownSpecialization(const CXXScopeSpec &SS) { 205 if (!isDependentScopeSpecifier(SS)) 206 return false; 207 208 NestedNameSpecifier *NNS 209 = static_cast<NestedNameSpecifier *>(SS.getScopeRep()); 210 return getCurrentInstantiationOf(NNS) == 0; 211} 212 213/// \brief If the given nested name specifier refers to the current 214/// instantiation, return the declaration that corresponds to that 215/// current instantiation (C++0x [temp.dep.type]p1). 216/// 217/// \param NNS a dependent nested name specifier. 218CXXRecordDecl *Sema::getCurrentInstantiationOf(NestedNameSpecifier *NNS) { 219 assert(getLangOptions().CPlusPlus && "Only callable in C++"); 220 assert(NNS->isDependent() && "Only dependent nested-name-specifier allowed"); 221 222 if (!NNS->getAsType()) 223 return 0; 224 225 QualType T = QualType(NNS->getAsType(), 0); 226 return ::getCurrentInstantiationOf(Context, CurContext, T); 227} 228 229/// \brief Require that the context specified by SS be complete. 230/// 231/// If SS refers to a type, this routine checks whether the type is 232/// complete enough (or can be made complete enough) for name lookup 233/// into the DeclContext. A type that is not yet completed can be 234/// considered "complete enough" if it is a class/struct/union/enum 235/// that is currently being defined. Or, if we have a type that names 236/// a class template specialization that is not a complete type, we 237/// will attempt to instantiate that class template. 238bool Sema::RequireCompleteDeclContext(const CXXScopeSpec &SS) { 239 if (!SS.isSet() || SS.isInvalid()) 240 return false; 241 242 DeclContext *DC = computeDeclContext(SS, true); 243 if (TagDecl *Tag = dyn_cast<TagDecl>(DC)) { 244 // If we're currently defining this type, then lookup into the 245 // type is okay: don't complain that it isn't complete yet. 246 const TagType *TagT = Context.getTypeDeclType(Tag)->getAs<TagType>(); 247 if (TagT->isBeingDefined()) 248 return false; 249 250 // The type must be complete. 251 return RequireCompleteType(SS.getRange().getBegin(), 252 Context.getTypeDeclType(Tag), 253 PDiag(diag::err_incomplete_nested_name_spec) 254 << SS.getRange()); 255 } 256 257 return false; 258} 259 260/// ActOnCXXGlobalScopeSpecifier - Return the object that represents the 261/// global scope ('::'). 262Sema::CXXScopeTy *Sema::ActOnCXXGlobalScopeSpecifier(Scope *S, 263 SourceLocation CCLoc) { 264 return NestedNameSpecifier::GlobalSpecifier(Context); 265} 266 267/// \brief Determines whether the given declaration is an valid acceptable 268/// result for name lookup of a nested-name-specifier. 269bool Sema::isAcceptableNestedNameSpecifier(NamedDecl *SD) { 270 if (!SD) 271 return false; 272 273 // Namespace and namespace aliases are fine. 274 if (isa<NamespaceDecl>(SD) || isa<NamespaceAliasDecl>(SD)) 275 return true; 276 277 if (!isa<TypeDecl>(SD)) 278 return false; 279 280 // Determine whether we have a class (or, in C++0x, an enum) or 281 // a typedef thereof. If so, build the nested-name-specifier. 282 QualType T = Context.getTypeDeclType(cast<TypeDecl>(SD)); 283 if (T->isDependentType()) 284 return true; 285 else if (TypedefDecl *TD = dyn_cast<TypedefDecl>(SD)) { 286 if (TD->getUnderlyingType()->isRecordType() || 287 (Context.getLangOptions().CPlusPlus0x && 288 TD->getUnderlyingType()->isEnumeralType())) 289 return true; 290 } else if (isa<RecordDecl>(SD) || 291 (Context.getLangOptions().CPlusPlus0x && isa<EnumDecl>(SD))) 292 return true; 293 294 return false; 295} 296 297/// \brief If the given nested-name-specifier begins with a bare identifier 298/// (e.g., Base::), perform name lookup for that identifier as a 299/// nested-name-specifier within the given scope, and return the result of that 300/// name lookup. 301NamedDecl *Sema::FindFirstQualifierInScope(Scope *S, NestedNameSpecifier *NNS) { 302 if (!S || !NNS) 303 return 0; 304 305 while (NNS->getPrefix()) 306 NNS = NNS->getPrefix(); 307 308 if (NNS->getKind() != NestedNameSpecifier::Identifier) 309 return 0; 310 311 LookupResult Found(*this, NNS->getAsIdentifier(), SourceLocation(), 312 LookupNestedNameSpecifierName); 313 LookupName(Found, S); 314 assert(!Found.isAmbiguous() && "Cannot handle ambiguities here yet"); 315 316 NamedDecl *Result = Found.getAsSingleDecl(Context); 317 if (isAcceptableNestedNameSpecifier(Result)) 318 return Result; 319 320 return 0; 321} 322 323/// \brief Build a new nested-name-specifier for "identifier::", as described 324/// by ActOnCXXNestedNameSpecifier. 325/// 326/// This routine differs only slightly from ActOnCXXNestedNameSpecifier, in 327/// that it contains an extra parameter \p ScopeLookupResult, which provides 328/// the result of name lookup within the scope of the nested-name-specifier 329/// that was computed at template definitino time. 330Sema::CXXScopeTy *Sema::BuildCXXNestedNameSpecifier(Scope *S, 331 const CXXScopeSpec &SS, 332 SourceLocation IdLoc, 333 SourceLocation CCLoc, 334 IdentifierInfo &II, 335 QualType ObjectType, 336 NamedDecl *ScopeLookupResult, 337 bool EnteringContext) { 338 NestedNameSpecifier *Prefix 339 = static_cast<NestedNameSpecifier *>(SS.getScopeRep()); 340 341 LookupResult Found(*this, &II, IdLoc, LookupNestedNameSpecifierName); 342 343 // Determine where to perform name lookup 344 DeclContext *LookupCtx = 0; 345 bool isDependent = false; 346 if (!ObjectType.isNull()) { 347 // This nested-name-specifier occurs in a member access expression, e.g., 348 // x->B::f, and we are looking into the type of the object. 349 assert(!SS.isSet() && "ObjectType and scope specifier cannot coexist"); 350 LookupCtx = computeDeclContext(ObjectType); 351 isDependent = ObjectType->isDependentType(); 352 } else if (SS.isSet()) { 353 // This nested-name-specifier occurs after another nested-name-specifier, 354 // so long into the context associated with the prior nested-name-specifier. 355 LookupCtx = computeDeclContext(SS, EnteringContext); 356 isDependent = isDependentScopeSpecifier(SS); 357 Found.setContextRange(SS.getRange()); 358 } 359 360 361 bool ObjectTypeSearchedInScope = false; 362 if (LookupCtx) { 363 // Perform "qualified" name lookup into the declaration context we 364 // computed, which is either the type of the base of a member access 365 // expression or the declaration context associated with a prior 366 // nested-name-specifier. 367 368 // The declaration context must be complete. 369 if (!LookupCtx->isDependentContext() && RequireCompleteDeclContext(SS)) 370 return 0; 371 372 LookupQualifiedName(Found, LookupCtx); 373 374 if (!ObjectType.isNull() && Found.empty()) { 375 // C++ [basic.lookup.classref]p4: 376 // If the id-expression in a class member access is a qualified-id of 377 // the form 378 // 379 // class-name-or-namespace-name::... 380 // 381 // the class-name-or-namespace-name following the . or -> operator is 382 // looked up both in the context of the entire postfix-expression and in 383 // the scope of the class of the object expression. If the name is found 384 // only in the scope of the class of the object expression, the name 385 // shall refer to a class-name. If the name is found only in the 386 // context of the entire postfix-expression, the name shall refer to a 387 // class-name or namespace-name. [...] 388 // 389 // Qualified name lookup into a class will not find a namespace-name, 390 // so we do not need to diagnoste that case specifically. However, 391 // this qualified name lookup may find nothing. In that case, perform 392 // unqualified name lookup in the given scope (if available) or 393 // reconstruct the result from when name lookup was performed at template 394 // definition time. 395 if (S) 396 LookupName(Found, S); 397 else if (ScopeLookupResult) 398 Found.addDecl(ScopeLookupResult); 399 400 ObjectTypeSearchedInScope = true; 401 } 402 } else if (isDependent) { 403 // We were not able to compute the declaration context for a dependent 404 // base object type or prior nested-name-specifier, so this 405 // nested-name-specifier refers to an unknown specialization. Just build 406 // a dependent nested-name-specifier. 407 if (!Prefix) 408 return NestedNameSpecifier::Create(Context, &II); 409 410 return NestedNameSpecifier::Create(Context, Prefix, &II); 411 } else { 412 // Perform unqualified name lookup in the current scope. 413 LookupName(Found, S); 414 } 415 416 // FIXME: Deal with ambiguities cleanly. 417 NamedDecl *SD = Found.getAsSingleDecl(Context); 418 if (isAcceptableNestedNameSpecifier(SD)) { 419 if (!ObjectType.isNull() && !ObjectTypeSearchedInScope) { 420 // C++ [basic.lookup.classref]p4: 421 // [...] If the name is found in both contexts, the 422 // class-name-or-namespace-name shall refer to the same entity. 423 // 424 // We already found the name in the scope of the object. Now, look 425 // into the current scope (the scope of the postfix-expression) to 426 // see if we can find the same name there. As above, if there is no 427 // scope, reconstruct the result from the template instantiation itself. 428 NamedDecl *OuterDecl; 429 if (S) { 430 LookupResult FoundOuter(*this, &II, IdLoc, LookupNestedNameSpecifierName); 431 LookupName(FoundOuter, S); 432 OuterDecl = FoundOuter.getAsSingleDecl(Context); 433 } else 434 OuterDecl = ScopeLookupResult; 435 436 if (isAcceptableNestedNameSpecifier(OuterDecl) && 437 OuterDecl->getCanonicalDecl() != SD->getCanonicalDecl() && 438 (!isa<TypeDecl>(OuterDecl) || !isa<TypeDecl>(SD) || 439 !Context.hasSameType( 440 Context.getTypeDeclType(cast<TypeDecl>(OuterDecl)), 441 Context.getTypeDeclType(cast<TypeDecl>(SD))))) { 442 Diag(IdLoc, diag::err_nested_name_member_ref_lookup_ambiguous) 443 << &II; 444 Diag(SD->getLocation(), diag::note_ambig_member_ref_object_type) 445 << ObjectType; 446 Diag(OuterDecl->getLocation(), diag::note_ambig_member_ref_scope); 447 448 // Fall through so that we'll pick the name we found in the object type, 449 // since that's probably what the user wanted anyway. 450 } 451 } 452 453 if (NamespaceDecl *Namespace = dyn_cast<NamespaceDecl>(SD)) 454 return NestedNameSpecifier::Create(Context, Prefix, Namespace); 455 456 // FIXME: It would be nice to maintain the namespace alias name, then 457 // see through that alias when resolving the nested-name-specifier down to 458 // a declaration context. 459 if (NamespaceAliasDecl *Alias = dyn_cast<NamespaceAliasDecl>(SD)) 460 return NestedNameSpecifier::Create(Context, Prefix, 461 462 Alias->getNamespace()); 463 464 QualType T = Context.getTypeDeclType(cast<TypeDecl>(SD)); 465 return NestedNameSpecifier::Create(Context, Prefix, false, 466 T.getTypePtr()); 467 } 468 469 // If we didn't find anything during our lookup, try again with 470 // ordinary name lookup, which can help us produce better error 471 // messages. 472 if (!SD) { 473 Found.clear(LookupOrdinaryName); 474 LookupName(Found, S); 475 SD = Found.getAsSingleDecl(Context); 476 } 477 478 unsigned DiagID; 479 if (SD) 480 DiagID = diag::err_expected_class_or_namespace; 481 else if (SS.isSet()) { 482 Diag(IdLoc, diag::err_no_member) << &II << LookupCtx << SS.getRange(); 483 return 0; 484 } else 485 DiagID = diag::err_undeclared_var_use; 486 487 if (SS.isSet()) 488 Diag(IdLoc, DiagID) << &II << SS.getRange(); 489 else 490 Diag(IdLoc, DiagID) << &II; 491 492 return 0; 493} 494 495/// ActOnCXXNestedNameSpecifier - Called during parsing of a 496/// nested-name-specifier. e.g. for "foo::bar::" we parsed "foo::" and now 497/// we want to resolve "bar::". 'SS' is empty or the previously parsed 498/// nested-name part ("foo::"), 'IdLoc' is the source location of 'bar', 499/// 'CCLoc' is the location of '::' and 'II' is the identifier for 'bar'. 500/// Returns a CXXScopeTy* object representing the C++ scope. 501Sema::CXXScopeTy *Sema::ActOnCXXNestedNameSpecifier(Scope *S, 502 const CXXScopeSpec &SS, 503 SourceLocation IdLoc, 504 SourceLocation CCLoc, 505 IdentifierInfo &II, 506 TypeTy *ObjectTypePtr, 507 bool EnteringContext) { 508 return BuildCXXNestedNameSpecifier(S, SS, IdLoc, CCLoc, II, 509 QualType::getFromOpaquePtr(ObjectTypePtr), 510 /*ScopeLookupResult=*/0, EnteringContext); 511} 512 513Sema::CXXScopeTy *Sema::ActOnCXXNestedNameSpecifier(Scope *S, 514 const CXXScopeSpec &SS, 515 TypeTy *Ty, 516 SourceRange TypeRange, 517 SourceLocation CCLoc) { 518 NestedNameSpecifier *Prefix 519 = static_cast<NestedNameSpecifier *>(SS.getScopeRep()); 520 QualType T = GetTypeFromParser(Ty); 521 return NestedNameSpecifier::Create(Context, Prefix, /*FIXME:*/false, 522 T.getTypePtr()); 523} 524 525/// ActOnCXXEnterDeclaratorScope - Called when a C++ scope specifier (global 526/// scope or nested-name-specifier) is parsed, part of a declarator-id. 527/// After this method is called, according to [C++ 3.4.3p3], names should be 528/// looked up in the declarator-id's scope, until the declarator is parsed and 529/// ActOnCXXExitDeclaratorScope is called. 530/// The 'SS' should be a non-empty valid CXXScopeSpec. 531bool Sema::ActOnCXXEnterDeclaratorScope(Scope *S, const CXXScopeSpec &SS) { 532 assert(SS.isSet() && "Parser passed invalid CXXScopeSpec."); 533 if (DeclContext *DC = computeDeclContext(SS, true)) { 534 // Before we enter a declarator's context, we need to make sure that 535 // it is a complete declaration context. 536 if (!DC->isDependentContext() && RequireCompleteDeclContext(SS)) 537 return true; 538 539 EnterDeclaratorContext(S, DC); 540 } 541 542 return false; 543} 544 545/// ActOnCXXExitDeclaratorScope - Called when a declarator that previously 546/// invoked ActOnCXXEnterDeclaratorScope(), is finished. 'SS' is the same 547/// CXXScopeSpec that was passed to ActOnCXXEnterDeclaratorScope as well. 548/// Used to indicate that names should revert to being looked up in the 549/// defining scope. 550void Sema::ActOnCXXExitDeclaratorScope(Scope *S, const CXXScopeSpec &SS) { 551 assert(SS.isSet() && "Parser passed invalid CXXScopeSpec."); 552 if (SS.isInvalid()) 553 return; 554 if (computeDeclContext(SS, true)) 555 ExitDeclaratorContext(S); 556} 557