Sema.cpp revision 75f48e16726933b75d77737f4af43620e21bfdcd 
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 "Sema.h"
16#include "llvm/ADT/DenseMap.h"
17#include "clang/AST/ASTConsumer.h"
18#include "clang/AST/ASTContext.h"
19#include "clang/AST/DeclObjC.h"
20#include "clang/AST/Expr.h"
21#include "clang/Lex/Preprocessor.h"
22#include "clang/Basic/PartialDiagnostic.h"
23#include "clang/Basic/TargetInfo.h"
24using namespace clang;
25
26/// ConvertQualTypeToStringFn - This function is used to pretty print the
27/// specified QualType as a string in diagnostics.
28static void ConvertArgToStringFn(Diagnostic::ArgumentKind Kind, intptr_t Val,
29                                 const char *Modifier, unsigned ModLen,
30                                 const char *Argument, unsigned ArgLen,
31                                 llvm::SmallVectorImpl<char> &Output,
32                                 void *Cookie) {
33  ASTContext &Context = *static_cast<ASTContext*>(Cookie);
34
35  std::string S;
36  if (Kind == Diagnostic::ak_qualtype) {
37    assert(ModLen == 0 && ArgLen == 0 &&
38           "Invalid modifier for QualType argument");
39
40    QualType Ty(QualType::getFromOpaquePtr(reinterpret_cast<void*>(Val)));
41
42    // FIXME: Playing with std::string is really slow.
43    S = Ty.getAsString(Context.PrintingPolicy);
44
45    // If this is a sugared type (like a typedef, typeof, etc), then unwrap one
46    // level of the sugar so that the type is more obvious to the user.
47    QualType DesugaredTy = Ty->getDesugaredType(true);
48    DesugaredTy.setCVRQualifiers(DesugaredTy.getCVRQualifiers() |
49                                 Ty.getCVRQualifiers());
50
51    if (Ty != DesugaredTy &&
52        // If the desugared type is a vector type, we don't want to expand it,
53        // it will turn into an attribute mess. People want their "vec4".
54        !isa<VectorType>(DesugaredTy) &&
55
56        // Don't aka just because we saw an elaborated type.
57        (!isa<ElaboratedType>(Ty) ||
58         cast<ElaboratedType>(Ty)->getUnderlyingType() != DesugaredTy) &&
59
60        // Don't desugar magic Objective-C types.
61        Ty.getUnqualifiedType() != Context.getObjCIdType() &&
62        Ty.getUnqualifiedType() != Context.getObjCClassType() &&
63        Ty.getUnqualifiedType() != Context.getObjCSelType() &&
64        Ty.getUnqualifiedType() != Context.getObjCProtoType() &&
65
66        // Not va_list.
67        Ty.getUnqualifiedType() != Context.getBuiltinVaListType()) {
68      S = "'"+S+"' (aka '";
69      S += DesugaredTy.getAsString(Context.PrintingPolicy);
70      S += "')";
71      Output.append(S.begin(), S.end());
72      return;
73    }
74
75  } else if (Kind == Diagnostic::ak_declarationname) {
76
77    DeclarationName N = DeclarationName::getFromOpaqueInteger(Val);
78    S = N.getAsString();
79
80    if (ModLen == 9 && !memcmp(Modifier, "objcclass", 9) && ArgLen == 0)
81      S = '+' + S;
82    else if (ModLen == 12 && !memcmp(Modifier, "objcinstance", 12) && ArgLen==0)
83      S = '-' + S;
84    else
85      assert(ModLen == 0 && ArgLen == 0 &&
86             "Invalid modifier for DeclarationName argument");
87  } else if (Kind == Diagnostic::ak_nameddecl) {
88    bool Qualified;
89    if (ModLen == 1 && Modifier[0] == 'q' && ArgLen == 0)
90      Qualified = true;
91    else {
92      assert(ModLen == 0 && ArgLen == 0 &&
93           "Invalid modifier for NamedDecl* argument");
94      Qualified = false;
95    }
96    reinterpret_cast<NamedDecl*>(Val)->getNameForDiagnostic(S,
97                                                         Context.PrintingPolicy,
98                                                            Qualified);
99  } else {
100    llvm::raw_string_ostream OS(S);
101    assert(Kind == Diagnostic::ak_nestednamespec);
102    reinterpret_cast<NestedNameSpecifier*> (Val)->print(OS,
103                                                        Context.PrintingPolicy);
104  }
105
106  Output.push_back('\'');
107  Output.append(S.begin(), S.end());
108  Output.push_back('\'');
109}
110
111
112static inline RecordDecl *CreateStructDecl(ASTContext &C, const char *Name) {
113  if (C.getLangOptions().CPlusPlus)
114    return CXXRecordDecl::Create(C, TagDecl::TK_struct,
115                                 C.getTranslationUnitDecl(),
116                                 SourceLocation(), &C.Idents.get(Name));
117
118  return RecordDecl::Create(C, TagDecl::TK_struct,
119                            C.getTranslationUnitDecl(),
120                            SourceLocation(), &C.Idents.get(Name));
121}
122
123void Sema::ActOnTranslationUnitScope(SourceLocation Loc, Scope *S) {
124  TUScope = S;
125  PushDeclContext(S, Context.getTranslationUnitDecl());
126
127  if (PP.getTargetInfo().getPointerWidth(0) >= 64) {
128    // Install [u]int128_t for 64-bit targets.
129    PushOnScopeChains(TypedefDecl::Create(Context, CurContext,
130                                          SourceLocation(),
131                                          &Context.Idents.get("__int128_t"),
132                                          Context.Int128Ty), TUScope);
133    PushOnScopeChains(TypedefDecl::Create(Context, CurContext,
134                                          SourceLocation(),
135                                          &Context.Idents.get("__uint128_t"),
136                                          Context.UnsignedInt128Ty), TUScope);
137  }
138
139
140  if (!PP.getLangOptions().ObjC1) return;
141
142  // Built-in ObjC types may already be set by PCHReader (hence isNull checks).
143  if (Context.getObjCSelType().isNull()) {
144    // Synthesize "typedef struct objc_selector *SEL;"
145    RecordDecl *SelTag = CreateStructDecl(Context, "objc_selector");
146    PushOnScopeChains(SelTag, TUScope);
147
148    QualType SelT = Context.getPointerType(Context.getTagDeclType(SelTag));
149    TypedefDecl *SelTypedef = TypedefDecl::Create(Context, CurContext,
150                                                  SourceLocation(),
151                                                  &Context.Idents.get("SEL"),
152                                                  SelT);
153    PushOnScopeChains(SelTypedef, TUScope);
154    Context.setObjCSelType(Context.getTypeDeclType(SelTypedef));
155  }
156
157  // Synthesize "@class Protocol;
158  if (Context.getObjCProtoType().isNull()) {
159    ObjCInterfaceDecl *ProtocolDecl =
160      ObjCInterfaceDecl::Create(Context, CurContext, SourceLocation(),
161                                &Context.Idents.get("Protocol"),
162                                SourceLocation(), true);
163    Context.setObjCProtoType(Context.getObjCInterfaceType(ProtocolDecl));
164    PushOnScopeChains(ProtocolDecl, TUScope);
165  }
166  // Create the built-in typedef for 'id'.
167  if (Context.getObjCIdType().isNull()) {
168    TypedefDecl *IdTypedef =
169      TypedefDecl::Create(
170        Context, CurContext, SourceLocation(), &Context.Idents.get("id"),
171        Context.getObjCObjectPointerType(Context.ObjCBuiltinIdTy)
172      );
173    PushOnScopeChains(IdTypedef, TUScope);
174    Context.setObjCIdType(Context.getTypeDeclType(IdTypedef));
175    Context.ObjCIdRedefinitionType = Context.getObjCIdType();
176  }
177  // Create the built-in typedef for 'Class'.
178  if (Context.getObjCClassType().isNull()) {
179    TypedefDecl *ClassTypedef =
180      TypedefDecl::Create(
181        Context, CurContext, SourceLocation(), &Context.Idents.get("Class"),
182        Context.getObjCObjectPointerType(Context.ObjCBuiltinClassTy)
183      );
184    PushOnScopeChains(ClassTypedef, TUScope);
185    Context.setObjCClassType(Context.getTypeDeclType(ClassTypedef));
186    Context.ObjCClassRedefinitionType = Context.getObjCClassType();
187  }
188}
189
190Sema::Sema(Preprocessor &pp, ASTContext &ctxt, ASTConsumer &consumer,
191           bool CompleteTranslationUnit)
192  : LangOpts(pp.getLangOptions()), PP(pp), Context(ctxt), Consumer(consumer),
193    Diags(PP.getDiagnostics()), SourceMgr(PP.getSourceManager()),
194    ExternalSource(0), CurContext(0), PreDeclaratorDC(0),
195    CurBlock(0), PackContext(0), IdResolver(pp.getLangOptions()),
196    GlobalNewDeleteDeclared(false), ExprEvalContext(PotentiallyEvaluated),
197    CompleteTranslationUnit(CompleteTranslationUnit),
198    NumSFINAEErrors(0), CurrentInstantiationScope(0) {
199
200  StdNamespace = 0;
201  TUScope = 0;
202  if (getLangOptions().CPlusPlus)
203    FieldCollector.reset(new CXXFieldCollector());
204
205  // Tell diagnostics how to render things from the AST library.
206  PP.getDiagnostics().SetArgToStringFn(ConvertArgToStringFn, &Context);
207}
208
209/// ImpCastExprToType - If Expr is not of type 'Type', insert an implicit cast.
210/// If there is already an implicit cast, merge into the existing one.
211/// If isLvalue, the result of the cast is an lvalue.
212void Sema::ImpCastExprToType(Expr *&Expr, QualType Ty,
213                             CastExpr::CastKind Kind, bool isLvalue) {
214  QualType ExprTy = Context.getCanonicalType(Expr->getType());
215  QualType TypeTy = Context.getCanonicalType(Ty);
216
217  if (ExprTy == TypeTy)
218    return;
219
220  if (Expr->getType().getTypePtr()->isPointerType() &&
221      Ty.getTypePtr()->isPointerType()) {
222    QualType ExprBaseType =
223      cast<PointerType>(ExprTy.getUnqualifiedType())->getPointeeType();
224    QualType BaseType =
225      cast<PointerType>(TypeTy.getUnqualifiedType())->getPointeeType();
226    if (ExprBaseType.getAddressSpace() != BaseType.getAddressSpace()) {
227      Diag(Expr->getExprLoc(), diag::err_implicit_pointer_address_space_cast)
228        << Expr->getSourceRange();
229    }
230  }
231
232  if (ImplicitCastExpr *ImpCast = dyn_cast<ImplicitCastExpr>(Expr)) {
233    ImpCast->setType(Ty);
234    ImpCast->setLvalueCast(isLvalue);
235  } else
236    Expr = new (Context) ImplicitCastExpr(Ty, Kind, Expr, isLvalue);
237}
238
239void Sema::DeleteExpr(ExprTy *E) {
240  if (E) static_cast<Expr*>(E)->Destroy(Context);
241}
242void Sema::DeleteStmt(StmtTy *S) {
243  if (S) static_cast<Stmt*>(S)->Destroy(Context);
244}
245
246/// ActOnEndOfTranslationUnit - This is called at the very end of the
247/// translation unit when EOF is reached and all but the top-level scope is
248/// popped.
249void Sema::ActOnEndOfTranslationUnit() {
250  // C++: Perform implicit template instantiations.
251  //
252  // FIXME: When we perform these implicit instantiations, we do not carefully
253  // keep track of the point of instantiation (C++ [temp.point]). This means
254  // that name lookup that occurs within the template instantiation will
255  // always happen at the end of the translation unit, so it will find
256  // some names that should not be found. Although this is common behavior
257  // for C++ compilers, it is technically wrong. In the future, we either need
258  // to be able to filter the results of name lookup or we need to perform
259  // template instantiations earlier.
260  PerformPendingImplicitInstantiations();
261
262  // Check for #pragma weak identifiers that were never declared
263  // FIXME: This will cause diagnostics to be emitted in a non-determinstic
264  // order!  Iterating over a densemap like this is bad.
265  for (llvm::DenseMap<IdentifierInfo*,WeakInfo>::iterator
266       I = WeakUndeclaredIdentifiers.begin(),
267       E = WeakUndeclaredIdentifiers.end(); I != E; ++I) {
268    if (I->second.getUsed()) continue;
269
270    Diag(I->second.getLocation(), diag::warn_weak_identifier_undeclared)
271      << I->first;
272  }
273
274  if (!CompleteTranslationUnit)
275    return;
276
277  // C99 6.9.2p2:
278  //   A declaration of an identifier for an object that has file
279  //   scope without an initializer, and without a storage-class
280  //   specifier or with the storage-class specifier static,
281  //   constitutes a tentative definition. If a translation unit
282  //   contains one or more tentative definitions for an identifier,
283  //   and the translation unit contains no external definition for
284  //   that identifier, then the behavior is exactly as if the
285  //   translation unit contains a file scope declaration of that
286  //   identifier, with the composite type as of the end of the
287  //   translation unit, with an initializer equal to 0.
288  for (unsigned i = 0, e = TentativeDefinitionList.size(); i != e; ++i) {
289    VarDecl *VD = TentativeDefinitions.lookup(TentativeDefinitionList[i]);
290
291    // If the tentative definition was completed, it will be in the list, but
292    // not the map.
293    if (VD == 0 || VD->isInvalidDecl() || !VD->isTentativeDefinition(Context))
294      continue;
295
296    if (const IncompleteArrayType *ArrayT
297        = Context.getAsIncompleteArrayType(VD->getType())) {
298      if (RequireCompleteType(VD->getLocation(),
299                              ArrayT->getElementType(),
300                              diag::err_tentative_def_incomplete_type_arr)) {
301        VD->setInvalidDecl();
302        continue;
303      }
304
305      // Set the length of the array to 1 (C99 6.9.2p5).
306      Diag(VD->getLocation(), diag::warn_tentative_incomplete_array);
307      llvm::APInt One(Context.getTypeSize(Context.getSizeType()), true);
308      QualType T
309        = Context.getConstantArrayWithoutExprType(ArrayT->getElementType(),
310                                                  One, ArrayType::Normal, 0);
311      VD->setType(T);
312    } else if (RequireCompleteType(VD->getLocation(), VD->getType(),
313                                   diag::err_tentative_def_incomplete_type))
314      VD->setInvalidDecl();
315
316    // Notify the consumer that we've completed a tentative definition.
317    if (!VD->isInvalidDecl())
318      Consumer.CompleteTentativeDefinition(VD);
319
320  }
321}
322
323
324//===----------------------------------------------------------------------===//
325// Helper functions.
326//===----------------------------------------------------------------------===//
327
328DeclContext *Sema::getFunctionLevelDeclContext() {
329  DeclContext *DC = PreDeclaratorDC ? PreDeclaratorDC : CurContext;
330
331  while (isa<BlockDecl>(DC))
332    DC = DC->getParent();
333
334  return DC;
335}
336
337/// getCurFunctionDecl - If inside of a function body, this returns a pointer
338/// to the function decl for the function being parsed.  If we're currently
339/// in a 'block', this returns the containing context.
340FunctionDecl *Sema::getCurFunctionDecl() {
341  DeclContext *DC = getFunctionLevelDeclContext();
342  return dyn_cast<FunctionDecl>(DC);
343}
344
345ObjCMethodDecl *Sema::getCurMethodDecl() {
346  DeclContext *DC = getFunctionLevelDeclContext();
347  return dyn_cast<ObjCMethodDecl>(DC);
348}
349
350NamedDecl *Sema::getCurFunctionOrMethodDecl() {
351  DeclContext *DC = getFunctionLevelDeclContext();
352  if (isa<ObjCMethodDecl>(DC) || isa<FunctionDecl>(DC))
353    return cast<NamedDecl>(DC);
354  return 0;
355}
356
357void Sema::DiagnoseMissingMember(SourceLocation MemberLoc,
358                                 DeclarationName Member,
359                                 NestedNameSpecifier *NNS, SourceRange Range) {
360  switch (NNS->getKind()) {
361  default: assert(0 && "Unexpected nested name specifier kind!");
362  case NestedNameSpecifier::TypeSpec: {
363    const Type *Ty = Context.getCanonicalType(NNS->getAsType());
364    RecordDecl *RD = cast<RecordType>(Ty)->getDecl();
365    Diag(MemberLoc, diag::err_typecheck_record_no_member)
366      << Member << RD->getTagKind() << RD << Range;
367    break;
368  }
369  case NestedNameSpecifier::Namespace: {
370    Diag(MemberLoc, diag::err_typecheck_namespace_no_member)
371       << Member << NNS->getAsNamespace() << Range;
372    break;
373  }
374  case NestedNameSpecifier::Global: {
375    Diag(MemberLoc, diag::err_typecheck_global_namespace_no_member)
376      << Member << Range;
377    break;
378  }
379  }
380}
381
382Sema::SemaDiagnosticBuilder::~SemaDiagnosticBuilder() {
383  if (!this->Emit())
384    return;
385
386  // If this is not a note, and we're in a template instantiation
387  // that is different from the last template instantiation where
388  // we emitted an error, print a template instantiation
389  // backtrace.
390  if (!SemaRef.Diags.isBuiltinNote(DiagID) &&
391      !SemaRef.ActiveTemplateInstantiations.empty() &&
392      SemaRef.ActiveTemplateInstantiations.back()
393        != SemaRef.LastTemplateInstantiationErrorContext) {
394    SemaRef.PrintInstantiationStack();
395    SemaRef.LastTemplateInstantiationErrorContext
396      = SemaRef.ActiveTemplateInstantiations.back();
397  }
398}
399
400Sema::SemaDiagnosticBuilder
401Sema::Diag(SourceLocation Loc, const PartialDiagnostic& PD) {
402  SemaDiagnosticBuilder Builder(Diag(Loc, PD.getDiagID()));
403  PD.Emit(Builder);
404
405  return Builder;
406}
407
408void Sema::ActOnComment(SourceRange Comment) {
409  Context.Comments.push_back(Comment);
410}
411
412