Sema.cpp revision aeb70b12ab1af1ba7e5e48cee3903d1a768bca90 
1//===--- Sema.cpp - AST Builder and Semantic Analysis Implementation ------===//
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 the actions class which performs semantic analysis and
11// builds an AST out of a parse stream.
12//
13//===----------------------------------------------------------------------===//
14
15#include "clang/Sema/Sema.h"
16#include "TargetAttributesSema.h"
17#include "llvm/ADT/DenseMap.h"
18#include "llvm/ADT/SmallSet.h"
19#include "llvm/ADT/APFloat.h"
20#include "clang/Sema/CXXFieldCollector.h"
21#include "clang/Sema/ExternalSemaSource.h"
22#include "clang/Sema/Scope.h"
23#include "clang/Sema/ScopeInfo.h"
24#include "clang/Sema/SemaConsumer.h"
25#include "clang/AST/ASTContext.h"
26#include "clang/AST/ASTDiagnostic.h"
27#include "clang/AST/DeclCXX.h"
28#include "clang/AST/DeclObjC.h"
29#include "clang/AST/Expr.h"
30#include "clang/Lex/Preprocessor.h"
31#include "clang/Basic/PartialDiagnostic.h"
32#include "clang/Basic/TargetInfo.h"
33using namespace clang;
34using namespace sema;
35
36FunctionScopeInfo::~FunctionScopeInfo() { }
37
38void FunctionScopeInfo::Clear(unsigned NumErrors) {
39  HasBranchProtectedScope = false;
40  HasBranchIntoScope = false;
41  HasIndirectGoto = false;
42
43  LabelMap.clear();
44  SwitchStack.clear();
45  Returns.clear();
46  NumErrorsAtStartOfFunction = NumErrors;
47}
48
49BlockScopeInfo::~BlockScopeInfo() { }
50
51void Sema::ActOnTranslationUnitScope(SourceLocation Loc, Scope *S) {
52  TUScope = S;
53  PushDeclContext(S, Context.getTranslationUnitDecl());
54
55  VAListTagName = PP.getIdentifierInfo("__va_list_tag");
56
57  if (!Context.isInt128Installed() && // May be set by ASTReader.
58      PP.getTargetInfo().getPointerWidth(0) >= 64) {
59    TypeSourceInfo *TInfo;
60
61    // Install [u]int128_t for 64-bit targets.
62    TInfo = Context.getTrivialTypeSourceInfo(Context.Int128Ty);
63    PushOnScopeChains(TypedefDecl::Create(Context, CurContext,
64                                          SourceLocation(),
65                                          &Context.Idents.get("__int128_t"),
66                                          TInfo), TUScope);
67
68    TInfo = Context.getTrivialTypeSourceInfo(Context.UnsignedInt128Ty);
69    PushOnScopeChains(TypedefDecl::Create(Context, CurContext,
70                                          SourceLocation(),
71                                          &Context.Idents.get("__uint128_t"),
72                                          TInfo), TUScope);
73    Context.setInt128Installed();
74  }
75
76
77  if (!PP.getLangOptions().ObjC1) return;
78
79  // Built-in ObjC types may already be set by ASTReader (hence isNull checks).
80  if (Context.getObjCSelType().isNull()) {
81    // Create the built-in typedef for 'SEL'.
82    QualType SelT = Context.getPointerType(Context.ObjCBuiltinSelTy);
83    TypeSourceInfo *SelInfo = Context.getTrivialTypeSourceInfo(SelT);
84    TypedefDecl *SelTypedef
85      = TypedefDecl::Create(Context, CurContext, SourceLocation(),
86                            &Context.Idents.get("SEL"), SelInfo);
87    PushOnScopeChains(SelTypedef, TUScope);
88    Context.setObjCSelType(Context.getTypeDeclType(SelTypedef));
89    Context.ObjCSelRedefinitionType = Context.getObjCSelType();
90  }
91
92  // Synthesize "@class Protocol;
93  if (Context.getObjCProtoType().isNull()) {
94    ObjCInterfaceDecl *ProtocolDecl =
95      ObjCInterfaceDecl::Create(Context, CurContext, SourceLocation(),
96                                &Context.Idents.get("Protocol"),
97                                SourceLocation(), true);
98    Context.setObjCProtoType(Context.getObjCInterfaceType(ProtocolDecl));
99    PushOnScopeChains(ProtocolDecl, TUScope, false);
100  }
101  // Create the built-in typedef for 'id'.
102  if (Context.getObjCIdType().isNull()) {
103    QualType T = Context.getObjCObjectType(Context.ObjCBuiltinIdTy, 0, 0);
104    T = Context.getObjCObjectPointerType(T);
105    TypeSourceInfo *IdInfo = Context.getTrivialTypeSourceInfo(T);
106    TypedefDecl *IdTypedef
107      = TypedefDecl::Create(Context, CurContext, SourceLocation(),
108                            &Context.Idents.get("id"), IdInfo);
109    PushOnScopeChains(IdTypedef, TUScope);
110    Context.setObjCIdType(Context.getTypeDeclType(IdTypedef));
111    Context.ObjCIdRedefinitionType = Context.getObjCIdType();
112  }
113  // Create the built-in typedef for 'Class'.
114  if (Context.getObjCClassType().isNull()) {
115    QualType T = Context.getObjCObjectType(Context.ObjCBuiltinClassTy, 0, 0);
116    T = Context.getObjCObjectPointerType(T);
117    TypeSourceInfo *ClassInfo = Context.getTrivialTypeSourceInfo(T);
118    TypedefDecl *ClassTypedef
119      = TypedefDecl::Create(Context, CurContext, SourceLocation(),
120                            &Context.Idents.get("Class"), ClassInfo);
121    PushOnScopeChains(ClassTypedef, TUScope);
122    Context.setObjCClassType(Context.getTypeDeclType(ClassTypedef));
123    Context.ObjCClassRedefinitionType = Context.getObjCClassType();
124  }
125}
126
127Sema::Sema(Preprocessor &pp, ASTContext &ctxt, ASTConsumer &consumer,
128           bool CompleteTranslationUnit,
129           CodeCompleteConsumer *CodeCompleter)
130  : TheTargetAttributesSema(0),
131    LangOpts(pp.getLangOptions()), PP(pp), Context(ctxt), Consumer(consumer),
132    Diags(PP.getDiagnostics()), SourceMgr(PP.getSourceManager()),
133    ExternalSource(0), CodeCompleter(CodeCompleter), CurContext(0),
134    PackContext(0), VisContext(0), ParsingDeclDepth(0),
135    IdResolver(pp.getLangOptions()), GlobalNewDeleteDeclared(false),
136    CompleteTranslationUnit(CompleteTranslationUnit),
137    NumSFINAEErrors(0), SuppressAccessChecking(false),
138    NonInstantiationEntries(0), CurrentInstantiationScope(0), TyposCorrected(0),
139    AnalysisWarnings(*this)
140{
141  TUScope = 0;
142  if (getLangOptions().CPlusPlus)
143    FieldCollector.reset(new CXXFieldCollector());
144
145  // Tell diagnostics how to render things from the AST library.
146  PP.getDiagnostics().SetArgToStringFn(&FormatASTNodeDiagnosticArgument,
147                                       &Context);
148
149  ExprEvalContexts.push_back(
150                  ExpressionEvaluationContextRecord(PotentiallyEvaluated, 0));
151
152  FunctionScopes.push_back(new FunctionScopeInfo(Diags.getNumErrors()));
153}
154
155void Sema::Initialize() {
156  // Tell the AST consumer about this Sema object.
157  Consumer.Initialize(Context);
158
159  // FIXME: Isn't this redundant with the initialization above?
160  if (SemaConsumer *SC = dyn_cast<SemaConsumer>(&Consumer))
161    SC->InitializeSema(*this);
162
163  // Tell the external Sema source about this Sema object.
164  if (ExternalSemaSource *ExternalSema
165      = dyn_cast_or_null<ExternalSemaSource>(Context.getExternalSource()))
166    ExternalSema->InitializeSema(*this);
167}
168
169Sema::~Sema() {
170  if (PackContext) FreePackedContext();
171  if (VisContext) FreeVisContext();
172  delete TheTargetAttributesSema;
173
174  // Kill all the active scopes.
175  for (unsigned I = 1, E = FunctionScopes.size(); I != E; ++I)
176    delete FunctionScopes[I];
177  if (FunctionScopes.size() == 1)
178    delete FunctionScopes[0];
179
180  // Tell the SemaConsumer to forget about us; we're going out of scope.
181  if (SemaConsumer *SC = dyn_cast<SemaConsumer>(&Consumer))
182    SC->ForgetSema();
183
184  // Detach from the external Sema source.
185  if (ExternalSemaSource *ExternalSema
186        = dyn_cast_or_null<ExternalSemaSource>(Context.getExternalSource()))
187    ExternalSema->ForgetSema();
188}
189
190/// ImpCastExprToType - If Expr is not of type 'Type', insert an implicit cast.
191/// If there is already an implicit cast, merge into the existing one.
192/// The result is of the given category.
193void Sema::ImpCastExprToType(Expr *&Expr, QualType Ty,
194                             CastKind Kind, ExprValueKind VK,
195                             const CXXCastPath *BasePath) {
196  QualType ExprTy = Context.getCanonicalType(Expr->getType());
197  QualType TypeTy = Context.getCanonicalType(Ty);
198
199  if (ExprTy == TypeTy)
200    return;
201
202  if (Expr->getType()->isPointerType() && Ty->isPointerType()) {
203    QualType ExprBaseType = cast<PointerType>(ExprTy)->getPointeeType();
204    QualType BaseType = cast<PointerType>(TypeTy)->getPointeeType();
205    if (ExprBaseType.getAddressSpace() != BaseType.getAddressSpace()) {
206      Diag(Expr->getExprLoc(), diag::err_implicit_pointer_address_space_cast)
207        << Expr->getSourceRange();
208    }
209  }
210
211  // If this is a derived-to-base cast to a through a virtual base, we
212  // need a vtable.
213  if (Kind == CK_DerivedToBase &&
214      BasePathInvolvesVirtualBase(*BasePath)) {
215    QualType T = Expr->getType();
216    if (const PointerType *Pointer = T->getAs<PointerType>())
217      T = Pointer->getPointeeType();
218    if (const RecordType *RecordTy = T->getAs<RecordType>())
219      MarkVTableUsed(Expr->getLocStart(),
220                     cast<CXXRecordDecl>(RecordTy->getDecl()));
221  }
222
223  if (ImplicitCastExpr *ImpCast = dyn_cast<ImplicitCastExpr>(Expr)) {
224    if (ImpCast->getCastKind() == Kind && (!BasePath || BasePath->empty())) {
225      ImpCast->setType(Ty);
226      ImpCast->setValueKind(VK);
227      return;
228    }
229  }
230
231  Expr = ImplicitCastExpr::Create(Context, Ty, Kind, Expr, BasePath, VK);
232}
233
234ExprValueKind Sema::CastCategory(Expr *E) {
235  Expr::Classification Classification = E->Classify(Context);
236  return Classification.isRValue() ? VK_RValue :
237      (Classification.isLValue() ? VK_LValue : VK_XValue);
238}
239
240void Sema::DeleteExpr(ExprTy *E) {
241}
242void Sema::DeleteStmt(StmtTy *S) {
243}
244
245/// \brief Used to prune the decls of Sema's UnusedFileScopedDecls vector.
246static bool ShouldRemoveFromUnused(Sema *SemaRef, const DeclaratorDecl *D) {
247  if (D->isUsed())
248    return true;
249
250  if (const FunctionDecl *FD = dyn_cast<FunctionDecl>(D)) {
251    // UnusedFileScopedDecls stores the first declaration.
252    // The declaration may have become definition so check again.
253    const FunctionDecl *DeclToCheck;
254    if (FD->hasBody(DeclToCheck))
255      return !SemaRef->ShouldWarnIfUnusedFileScopedDecl(DeclToCheck);
256
257    // Later redecls may add new information resulting in not having to warn,
258    // so check again.
259    DeclToCheck = FD->getMostRecentDeclaration();
260    if (DeclToCheck != FD)
261      return !SemaRef->ShouldWarnIfUnusedFileScopedDecl(DeclToCheck);
262  }
263
264  if (const VarDecl *VD = dyn_cast<VarDecl>(D)) {
265    // UnusedFileScopedDecls stores the first declaration.
266    // The declaration may have become definition so check again.
267    const VarDecl *DeclToCheck = VD->getDefinition();
268    if (DeclToCheck)
269      return !SemaRef->ShouldWarnIfUnusedFileScopedDecl(DeclToCheck);
270
271    // Later redecls may add new information resulting in not having to warn,
272    // so check again.
273    DeclToCheck = VD->getMostRecentDeclaration();
274    if (DeclToCheck != VD)
275      return !SemaRef->ShouldWarnIfUnusedFileScopedDecl(DeclToCheck);
276  }
277
278  return false;
279}
280
281/// ActOnEndOfTranslationUnit - This is called at the very end of the
282/// translation unit when EOF is reached and all but the top-level scope is
283/// popped.
284void Sema::ActOnEndOfTranslationUnit() {
285  // At PCH writing, implicit instantiations and VTable handling info are
286  // stored and performed when the PCH is included.
287  if (CompleteTranslationUnit)
288    while (1) {
289      // C++: Perform implicit template instantiations.
290      //
291      // FIXME: When we perform these implicit instantiations, we do not
292      // carefully keep track of the point of instantiation (C++ [temp.point]).
293      // This means that name lookup that occurs within the template
294      // instantiation will always happen at the end of the translation unit,
295      // so it will find some names that should not be found. Although this is
296      // common behavior for C++ compilers, it is technically wrong. In the
297      // future, we either need to be able to filter the results of name lookup
298      // or we need to perform template instantiations earlier.
299      PerformPendingInstantiations();
300
301      /// If DefinedUsedVTables ends up marking any virtual member
302      /// functions it might lead to more pending template
303      /// instantiations, which is why we need to loop here.
304      if (!DefineUsedVTables())
305        break;
306    }
307
308  // Remove file scoped decls that turned out to be used.
309  UnusedFileScopedDecls.erase(std::remove_if(UnusedFileScopedDecls.begin(),
310                                             UnusedFileScopedDecls.end(),
311                              std::bind1st(std::ptr_fun(ShouldRemoveFromUnused),
312                                           this)),
313                              UnusedFileScopedDecls.end());
314
315  if (!CompleteTranslationUnit) {
316    TUScope = 0;
317    return;
318  }
319
320  // Check for #pragma weak identifiers that were never declared
321  // FIXME: This will cause diagnostics to be emitted in a non-determinstic
322  // order!  Iterating over a densemap like this is bad.
323  for (llvm::DenseMap<IdentifierInfo*,WeakInfo>::iterator
324       I = WeakUndeclaredIdentifiers.begin(),
325       E = WeakUndeclaredIdentifiers.end(); I != E; ++I) {
326    if (I->second.getUsed()) continue;
327
328    Diag(I->second.getLocation(), diag::warn_weak_identifier_undeclared)
329      << I->first;
330  }
331
332  // C99 6.9.2p2:
333  //   A declaration of an identifier for an object that has file
334  //   scope without an initializer, and without a storage-class
335  //   specifier or with the storage-class specifier static,
336  //   constitutes a tentative definition. If a translation unit
337  //   contains one or more tentative definitions for an identifier,
338  //   and the translation unit contains no external definition for
339  //   that identifier, then the behavior is exactly as if the
340  //   translation unit contains a file scope declaration of that
341  //   identifier, with the composite type as of the end of the
342  //   translation unit, with an initializer equal to 0.
343  llvm::SmallSet<VarDecl *, 32> Seen;
344  for (unsigned i = 0, e = TentativeDefinitions.size(); i != e; ++i) {
345    VarDecl *VD = TentativeDefinitions[i]->getActingDefinition();
346
347    // If the tentative definition was completed, getActingDefinition() returns
348    // null. If we've already seen this variable before, insert()'s second
349    // return value is false.
350    if (VD == 0 || VD->isInvalidDecl() || !Seen.insert(VD))
351      continue;
352
353    if (const IncompleteArrayType *ArrayT
354        = Context.getAsIncompleteArrayType(VD->getType())) {
355      if (RequireCompleteType(VD->getLocation(),
356                              ArrayT->getElementType(),
357                              diag::err_tentative_def_incomplete_type_arr)) {
358        VD->setInvalidDecl();
359        continue;
360      }
361
362      // Set the length of the array to 1 (C99 6.9.2p5).
363      Diag(VD->getLocation(), diag::warn_tentative_incomplete_array);
364      llvm::APInt One(Context.getTypeSize(Context.getSizeType()), true);
365      QualType T = Context.getConstantArrayType(ArrayT->getElementType(),
366                                                One, ArrayType::Normal, 0);
367      VD->setType(T);
368    } else if (RequireCompleteType(VD->getLocation(), VD->getType(),
369                                   diag::err_tentative_def_incomplete_type))
370      VD->setInvalidDecl();
371
372    // Notify the consumer that we've completed a tentative definition.
373    if (!VD->isInvalidDecl())
374      Consumer.CompleteTentativeDefinition(VD);
375
376  }
377
378  // Output warning for unused file scoped decls.
379  for (llvm::SmallVectorImpl<const DeclaratorDecl*>::iterator
380         I = UnusedFileScopedDecls.begin(),
381         E = UnusedFileScopedDecls.end(); I != E; ++I) {
382    if (const FunctionDecl *FD = dyn_cast<FunctionDecl>(*I)) {
383      const FunctionDecl *DiagD;
384      if (!FD->hasBody(DiagD))
385        DiagD = FD;
386      Diag(DiagD->getLocation(),
387           isa<CXXMethodDecl>(DiagD) ? diag::warn_unused_member_function
388                                     : diag::warn_unused_function)
389            << DiagD->getDeclName();
390    } else {
391      const VarDecl *DiagD = cast<VarDecl>(*I)->getDefinition();
392      if (!DiagD)
393        DiagD = cast<VarDecl>(*I);
394      Diag(DiagD->getLocation(), diag::warn_unused_variable)
395            << DiagD->getDeclName();
396    }
397  }
398
399  TUScope = 0;
400}
401
402
403//===----------------------------------------------------------------------===//
404// Helper functions.
405//===----------------------------------------------------------------------===//
406
407DeclContext *Sema::getFunctionLevelDeclContext() {
408  DeclContext *DC = CurContext;
409
410  while (isa<BlockDecl>(DC) || isa<EnumDecl>(DC))
411    DC = DC->getParent();
412
413  return DC;
414}
415
416/// getCurFunctionDecl - If inside of a function body, this returns a pointer
417/// to the function decl for the function being parsed.  If we're currently
418/// in a 'block', this returns the containing context.
419FunctionDecl *Sema::getCurFunctionDecl() {
420  DeclContext *DC = getFunctionLevelDeclContext();
421  return dyn_cast<FunctionDecl>(DC);
422}
423
424ObjCMethodDecl *Sema::getCurMethodDecl() {
425  DeclContext *DC = getFunctionLevelDeclContext();
426  return dyn_cast<ObjCMethodDecl>(DC);
427}
428
429NamedDecl *Sema::getCurFunctionOrMethodDecl() {
430  DeclContext *DC = getFunctionLevelDeclContext();
431  if (isa<ObjCMethodDecl>(DC) || isa<FunctionDecl>(DC))
432    return cast<NamedDecl>(DC);
433  return 0;
434}
435
436Sema::SemaDiagnosticBuilder::~SemaDiagnosticBuilder() {
437  if (!this->Emit())
438    return;
439
440  // If this is not a note, and we're in a template instantiation
441  // that is different from the last template instantiation where
442  // we emitted an error, print a template instantiation
443  // backtrace.
444  if (!SemaRef.Diags.isBuiltinNote(DiagID) &&
445      !SemaRef.ActiveTemplateInstantiations.empty() &&
446      SemaRef.ActiveTemplateInstantiations.back()
447        != SemaRef.LastTemplateInstantiationErrorContext) {
448    SemaRef.PrintInstantiationStack();
449    SemaRef.LastTemplateInstantiationErrorContext
450      = SemaRef.ActiveTemplateInstantiations.back();
451  }
452}
453
454Sema::SemaDiagnosticBuilder Sema::Diag(SourceLocation Loc, unsigned DiagID) {
455  if (isSFINAEContext()) {
456    switch (Diagnostic::getDiagnosticSFINAEResponse(DiagID)) {
457    case Diagnostic::SFINAE_Report:
458      // Fall through; we'll report the diagnostic below.
459      break;
460
461    case Diagnostic::SFINAE_SubstitutionFailure:
462      // Count this failure so that we know that template argument deduction
463      // has failed.
464      ++NumSFINAEErrors;
465      // Fall through
466
467    case Diagnostic::SFINAE_Suppress:
468      // Suppress this diagnostic.
469      Diags.setLastDiagnosticIgnored();
470      return SemaDiagnosticBuilder(*this);
471    }
472  }
473
474  DiagnosticBuilder DB = Diags.Report(FullSourceLoc(Loc, SourceMgr), DiagID);
475  return SemaDiagnosticBuilder(DB, *this, DiagID);
476}
477
478Sema::SemaDiagnosticBuilder
479Sema::Diag(SourceLocation Loc, const PartialDiagnostic& PD) {
480  SemaDiagnosticBuilder Builder(Diag(Loc, PD.getDiagID()));
481  PD.Emit(Builder);
482
483  return Builder;
484}
485
486/// \brief Determines the active Scope associated with the given declaration
487/// context.
488///
489/// This routine maps a declaration context to the active Scope object that
490/// represents that declaration context in the parser. It is typically used
491/// from "scope-less" code (e.g., template instantiation, lazy creation of
492/// declarations) that injects a name for name-lookup purposes and, therefore,
493/// must update the Scope.
494///
495/// \returns The scope corresponding to the given declaraion context, or NULL
496/// if no such scope is open.
497Scope *Sema::getScopeForContext(DeclContext *Ctx) {
498
499  if (!Ctx)
500    return 0;
501
502  Ctx = Ctx->getPrimaryContext();
503  for (Scope *S = getCurScope(); S; S = S->getParent()) {
504    // Ignore scopes that cannot have declarations. This is important for
505    // out-of-line definitions of static class members.
506    if (S->getFlags() & (Scope::DeclScope | Scope::TemplateParamScope))
507      if (DeclContext *Entity = static_cast<DeclContext *> (S->getEntity()))
508        if (Ctx == Entity->getPrimaryContext())
509          return S;
510  }
511
512  return 0;
513}
514
515/// \brief Enter a new function scope
516void Sema::PushFunctionScope() {
517  if (FunctionScopes.size() == 1) {
518    // Use the "top" function scope rather than having to allocate
519    // memory for a new scope.
520    FunctionScopes.back()->Clear(getDiagnostics().getNumErrors());
521    FunctionScopes.push_back(FunctionScopes.back());
522    return;
523  }
524
525  FunctionScopes.push_back(
526                      new FunctionScopeInfo(getDiagnostics().getNumErrors()));
527}
528
529void Sema::PushBlockScope(Scope *BlockScope, BlockDecl *Block) {
530  FunctionScopes.push_back(new BlockScopeInfo(getDiagnostics().getNumErrors(),
531                                              BlockScope, Block));
532}
533
534void Sema::PopFunctionOrBlockScope() {
535  FunctionScopeInfo *Scope = FunctionScopes.pop_back_val();
536  assert(!FunctionScopes.empty() && "mismatched push/pop!");
537  if (FunctionScopes.back() != Scope)
538    delete Scope;
539}
540
541/// \brief Determine whether any errors occurred within this function/method/
542/// block.
543bool Sema::hasAnyErrorsInThisFunction() const {
544  return getCurFunction()->NumErrorsAtStartOfFunction
545             != getDiagnostics().getNumErrors();
546}
547
548BlockScopeInfo *Sema::getCurBlock() {
549  if (FunctionScopes.empty())
550    return 0;
551
552  return dyn_cast<BlockScopeInfo>(FunctionScopes.back());
553}
554
555// Pin this vtable to this file.
556ExternalSemaSource::~ExternalSemaSource() {}
557