Sema.cpp revision 13dcd00615de5c4279d97bdf63cd5f0a14fd9dcc 
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 "llvm/ADT/APFloat.h"
18#include "clang/AST/ASTConsumer.h"
19#include "clang/AST/ASTContext.h"
20#include "clang/AST/DeclObjC.h"
21#include "clang/AST/Expr.h"
22#include "clang/Lex/Preprocessor.h"
23#include "clang/Basic/PartialDiagnostic.h"
24#include "clang/Basic/TargetInfo.h"
25using namespace clang;
26
27/// Determines whether we should have an a.k.a. clause when
28/// pretty-printing a type.  There are three main criteria:
29///
30/// 1) Some types provide very minimal sugar that doesn't impede the
31///    user's understanding --- for example, elaborated type
32///    specifiers.  If this is all the sugar we see, we don't want an
33///    a.k.a. clause.
34/// 2) Some types are technically sugared but are much more familiar
35///    when seen in their sugared form --- for example, va_list,
36///    vector types, and the magic Objective C types.  We don't
37///    want to desugar these, even if we do produce an a.k.a. clause.
38/// 3) Some types may have already been desugared previously in this diagnostic.
39///    if this is the case, doing another "aka" would just be clutter.
40///
41static bool ShouldAKA(ASTContext &Context, QualType QT,
42                      const Diagnostic::ArgumentValue *PrevArgs,
43                      unsigned NumPrevArgs,
44                      QualType &DesugaredQT) {
45  QualType InputTy = QT;
46
47  bool AKA = false;
48  QualifierCollector Qc;
49
50  while (true) {
51    const Type *Ty = Qc.strip(QT);
52
53    // Don't aka just because we saw an elaborated type...
54    if (isa<ElaboratedType>(Ty)) {
55      QT = cast<ElaboratedType>(Ty)->desugar();
56      continue;
57    }
58
59    // ...or a qualified name type...
60    if (isa<QualifiedNameType>(Ty)) {
61      QT = cast<QualifiedNameType>(Ty)->desugar();
62      continue;
63    }
64
65    // ...or a substituted template type parameter.
66    if (isa<SubstTemplateTypeParmType>(Ty)) {
67      QT = cast<SubstTemplateTypeParmType>(Ty)->desugar();
68      continue;
69    }
70
71    // Don't desugar template specializations.
72    if (isa<TemplateSpecializationType>(Ty))
73      break;
74
75    // Don't desugar magic Objective-C types.
76    if (QualType(Ty,0) == Context.getObjCIdType() ||
77        QualType(Ty,0) == Context.getObjCClassType() ||
78        QualType(Ty,0) == Context.getObjCSelType() ||
79        QualType(Ty,0) == Context.getObjCProtoType())
80      break;
81
82    // Don't desugar va_list.
83    if (QualType(Ty,0) == Context.getBuiltinVaListType())
84      break;
85
86    // Otherwise, do a single-step desugar.
87    QualType Underlying;
88    bool IsSugar = false;
89    switch (Ty->getTypeClass()) {
90#define ABSTRACT_TYPE(Class, Base)
91#define TYPE(Class, Base) \
92    case Type::Class: { \
93      const Class##Type *CTy = cast<Class##Type>(Ty); \
94      if (CTy->isSugared()) { \
95        IsSugar = true; \
96        Underlying = CTy->desugar(); \
97      } \
98      break; \
99    }
100#include "clang/AST/TypeNodes.def"
101    }
102
103    // If it wasn't sugared, we're done.
104    if (!IsSugar)
105      break;
106
107    // If the desugared type is a vector type, we don't want to expand
108    // it, it will turn into an attribute mess. People want their "vec4".
109    if (isa<VectorType>(Underlying))
110      break;
111
112    // Otherwise, we're tearing through something opaque; note that
113    // we'll eventually need an a.k.a. clause and keep going.
114    AKA = true;
115    QT = Underlying;
116    continue;
117  }
118
119  // If we never tore through opaque sugar, don't print aka.
120  if (!AKA) return false;
121
122  // If we did, check to see if we already desugared this type in this
123  // diagnostic.  If so, don't do it again.
124  for (unsigned i = 0; i != NumPrevArgs; ++i) {
125    // TODO: Handle ak_declcontext case.
126    if (PrevArgs[i].first == Diagnostic::ak_qualtype) {
127      void *Ptr = (void*)PrevArgs[i].second;
128      QualType PrevTy(QualType::getFromOpaquePtr(Ptr));
129      if (PrevTy == InputTy)
130        return false;
131    }
132  }
133
134  DesugaredQT = Qc.apply(QT);
135  return true;
136}
137
138/// \brief Convert the given type to a string suitable for printing as part of
139/// a diagnostic.
140///
141/// \param Context the context in which the type was allocated
142/// \param Ty the type to print
143static std::string
144ConvertTypeToDiagnosticString(ASTContext &Context, QualType Ty,
145                              const Diagnostic::ArgumentValue *PrevArgs,
146                              unsigned NumPrevArgs) {
147  // FIXME: Playing with std::string is really slow.
148  std::string S = Ty.getAsString(Context.PrintingPolicy);
149
150  // Consider producing an a.k.a. clause if removing all the direct
151  // sugar gives us something "significantly different".
152
153  QualType DesugaredTy;
154  if (ShouldAKA(Context, Ty, PrevArgs, NumPrevArgs, DesugaredTy)) {
155    S = "'"+S+"' (aka '";
156    S += DesugaredTy.getAsString(Context.PrintingPolicy);
157    S += "')";
158    return S;
159  }
160
161  S = "'" + S + "'";
162  return S;
163}
164
165/// ConvertQualTypeToStringFn - This function is used to pretty print the
166/// specified QualType as a string in diagnostics.
167static void ConvertArgToStringFn(Diagnostic::ArgumentKind Kind, intptr_t Val,
168                                 const char *Modifier, unsigned ModLen,
169                                 const char *Argument, unsigned ArgLen,
170                                 const Diagnostic::ArgumentValue *PrevArgs,
171                                 unsigned NumPrevArgs,
172                                 llvm::SmallVectorImpl<char> &Output,
173                                 void *Cookie) {
174  ASTContext &Context = *static_cast<ASTContext*>(Cookie);
175
176  std::string S;
177  bool NeedQuotes = true;
178
179  switch (Kind) {
180  default: assert(0 && "unknown ArgumentKind");
181  case Diagnostic::ak_qualtype: {
182    assert(ModLen == 0 && ArgLen == 0 &&
183           "Invalid modifier for QualType argument");
184
185    QualType Ty(QualType::getFromOpaquePtr(reinterpret_cast<void*>(Val)));
186    S = ConvertTypeToDiagnosticString(Context, Ty, PrevArgs, NumPrevArgs);
187    NeedQuotes = false;
188    break;
189  }
190  case Diagnostic::ak_declarationname: {
191    DeclarationName N = DeclarationName::getFromOpaqueInteger(Val);
192    S = N.getAsString();
193
194    if (ModLen == 9 && !memcmp(Modifier, "objcclass", 9) && ArgLen == 0)
195      S = '+' + S;
196    else if (ModLen == 12 && !memcmp(Modifier, "objcinstance", 12) && ArgLen==0)
197      S = '-' + S;
198    else
199      assert(ModLen == 0 && ArgLen == 0 &&
200             "Invalid modifier for DeclarationName argument");
201    break;
202  }
203  case Diagnostic::ak_nameddecl: {
204    bool Qualified;
205    if (ModLen == 1 && Modifier[0] == 'q' && ArgLen == 0)
206      Qualified = true;
207    else {
208      assert(ModLen == 0 && ArgLen == 0 &&
209           "Invalid modifier for NamedDecl* argument");
210      Qualified = false;
211    }
212    reinterpret_cast<NamedDecl*>(Val)->
213      getNameForDiagnostic(S, Context.PrintingPolicy, Qualified);
214    break;
215  }
216  case Diagnostic::ak_nestednamespec: {
217    llvm::raw_string_ostream OS(S);
218    reinterpret_cast<NestedNameSpecifier*>(Val)->print(OS,
219                                                       Context.PrintingPolicy);
220    NeedQuotes = false;
221    break;
222  }
223  case Diagnostic::ak_declcontext: {
224    DeclContext *DC = reinterpret_cast<DeclContext *> (Val);
225    assert(DC && "Should never have a null declaration context");
226
227    if (DC->isTranslationUnit()) {
228      // FIXME: Get these strings from some localized place
229      if (Context.getLangOptions().CPlusPlus)
230        S = "the global namespace";
231      else
232        S = "the global scope";
233    } else if (TypeDecl *Type = dyn_cast<TypeDecl>(DC)) {
234      S = ConvertTypeToDiagnosticString(Context, Context.getTypeDeclType(Type),
235                                        PrevArgs, NumPrevArgs);
236    } else {
237      // FIXME: Get these strings from some localized place
238      NamedDecl *ND = cast<NamedDecl>(DC);
239      if (isa<NamespaceDecl>(ND))
240        S += "namespace ";
241      else if (isa<ObjCMethodDecl>(ND))
242        S += "method ";
243      else if (isa<FunctionDecl>(ND))
244        S += "function ";
245
246      S += "'";
247      ND->getNameForDiagnostic(S, Context.PrintingPolicy, true);
248      S += "'";
249    }
250    NeedQuotes = false;
251    break;
252  }
253  }
254
255  if (NeedQuotes)
256    Output.push_back('\'');
257
258  Output.append(S.begin(), S.end());
259
260  if (NeedQuotes)
261    Output.push_back('\'');
262}
263
264
265static inline RecordDecl *CreateStructDecl(ASTContext &C, const char *Name) {
266  if (C.getLangOptions().CPlusPlus)
267    return CXXRecordDecl::Create(C, TagDecl::TK_struct,
268                                 C.getTranslationUnitDecl(),
269                                 SourceLocation(), &C.Idents.get(Name));
270
271  return RecordDecl::Create(C, TagDecl::TK_struct,
272                            C.getTranslationUnitDecl(),
273                            SourceLocation(), &C.Idents.get(Name));
274}
275
276void Sema::ActOnTranslationUnitScope(SourceLocation Loc, Scope *S) {
277  TUScope = S;
278  PushDeclContext(S, Context.getTranslationUnitDecl());
279
280  if (PP.getTargetInfo().getPointerWidth(0) >= 64) {
281    DeclaratorInfo *DInfo;
282
283    // Install [u]int128_t for 64-bit targets.
284    DInfo = Context.getTrivialDeclaratorInfo(Context.Int128Ty);
285    PushOnScopeChains(TypedefDecl::Create(Context, CurContext,
286                                          SourceLocation(),
287                                          &Context.Idents.get("__int128_t"),
288                                          DInfo), TUScope);
289
290    DInfo = Context.getTrivialDeclaratorInfo(Context.UnsignedInt128Ty);
291    PushOnScopeChains(TypedefDecl::Create(Context, CurContext,
292                                          SourceLocation(),
293                                          &Context.Idents.get("__uint128_t"),
294                                          DInfo), TUScope);
295  }
296
297
298  if (!PP.getLangOptions().ObjC1) return;
299
300  // Built-in ObjC types may already be set by PCHReader (hence isNull checks).
301  if (Context.getObjCSelType().isNull()) {
302    // Create the built-in typedef for 'SEL'.
303    QualType SelT = Context.getObjCObjectPointerType(Context.ObjCBuiltinSelTy);
304    DeclaratorInfo *SelInfo = Context.getTrivialDeclaratorInfo(SelT);
305    TypedefDecl *SelTypedef
306      = TypedefDecl::Create(Context, CurContext, SourceLocation(),
307                            &Context.Idents.get("SEL"), SelInfo);
308    PushOnScopeChains(SelTypedef, TUScope);
309    Context.setObjCSelType(Context.getTypeDeclType(SelTypedef));
310    Context.ObjCSELRedefinitionType = Context.getObjCSelType();
311  }
312
313  // Synthesize "@class Protocol;
314  if (Context.getObjCProtoType().isNull()) {
315    ObjCInterfaceDecl *ProtocolDecl =
316      ObjCInterfaceDecl::Create(Context, CurContext, SourceLocation(),
317                                &Context.Idents.get("Protocol"),
318                                SourceLocation(), true);
319    Context.setObjCProtoType(Context.getObjCInterfaceType(ProtocolDecl));
320    PushOnScopeChains(ProtocolDecl, TUScope, false);
321  }
322  // Create the built-in typedef for 'id'.
323  if (Context.getObjCIdType().isNull()) {
324    QualType IdT = Context.getObjCObjectPointerType(Context.ObjCBuiltinIdTy);
325    DeclaratorInfo *IdInfo = Context.getTrivialDeclaratorInfo(IdT);
326    TypedefDecl *IdTypedef
327      = TypedefDecl::Create(Context, CurContext, SourceLocation(),
328                            &Context.Idents.get("id"), IdInfo);
329    PushOnScopeChains(IdTypedef, TUScope);
330    Context.setObjCIdType(Context.getTypeDeclType(IdTypedef));
331    Context.ObjCIdRedefinitionType = Context.getObjCIdType();
332  }
333  // Create the built-in typedef for 'Class'.
334  if (Context.getObjCClassType().isNull()) {
335    QualType ClassType
336      = Context.getObjCObjectPointerType(Context.ObjCBuiltinClassTy);
337    DeclaratorInfo *ClassInfo = Context.getTrivialDeclaratorInfo(ClassType);
338    TypedefDecl *ClassTypedef
339      = TypedefDecl::Create(Context, CurContext, SourceLocation(),
340                            &Context.Idents.get("Class"), ClassInfo);
341    PushOnScopeChains(ClassTypedef, TUScope);
342    Context.setObjCClassType(Context.getTypeDeclType(ClassTypedef));
343    Context.ObjCClassRedefinitionType = Context.getObjCClassType();
344  }
345}
346
347Sema::Sema(Preprocessor &pp, ASTContext &ctxt, ASTConsumer &consumer,
348           bool CompleteTranslationUnit,
349           CodeCompleteConsumer *CodeCompleter)
350  : LangOpts(pp.getLangOptions()), PP(pp), Context(ctxt), Consumer(consumer),
351    Diags(PP.getDiagnostics()), SourceMgr(PP.getSourceManager()),
352    ExternalSource(0), CodeCompleter(CodeCompleter), CurContext(0),
353    PreDeclaratorDC(0), CurBlock(0), PackContext(0), ParsingDeclDepth(0),
354    IdResolver(pp.getLangOptions()), StdNamespace(0), StdBadAlloc(0),
355    GlobalNewDeleteDeclared(false), ExprEvalContext(PotentiallyEvaluated),
356    CompleteTranslationUnit(CompleteTranslationUnit),
357    NumSFINAEErrors(0), NonInstantiationEntries(0),
358    CurrentInstantiationScope(0)
359{
360  TUScope = 0;
361  if (getLangOptions().CPlusPlus)
362    FieldCollector.reset(new CXXFieldCollector());
363
364  // Tell diagnostics how to render things from the AST library.
365  PP.getDiagnostics().SetArgToStringFn(ConvertArgToStringFn, &Context);
366}
367
368/// Retrieves the width and signedness of the given integer type,
369/// or returns false if it is not an integer type.
370///
371/// \param T must be canonical
372static bool getIntProperties(ASTContext &C, const Type *T,
373                             unsigned &BitWidth, bool &Signed) {
374  assert(T->isCanonicalUnqualified());
375
376  if (const VectorType *VT = dyn_cast<VectorType>(T))
377    T = VT->getElementType().getTypePtr();
378  if (const ComplexType *CT = dyn_cast<ComplexType>(T))
379    T = CT->getElementType().getTypePtr();
380
381  if (const BuiltinType *BT = dyn_cast<BuiltinType>(T)) {
382    if (!BT->isInteger()) return false;
383
384    BitWidth = C.getIntWidth(QualType(T, 0));
385    Signed = BT->isSignedInteger();
386    return true;
387  }
388
389  if (const FixedWidthIntType *FWIT = dyn_cast<FixedWidthIntType>(T)) {
390    BitWidth = FWIT->getWidth();
391    Signed = FWIT->isSigned();
392    return true;
393  }
394
395  return false;
396}
397
398/// Checks whether the given value will have the same value if it it
399/// is truncated to the given width, then extended back to the
400/// original width.
401static bool IsSameIntAfterCast(const llvm::APSInt &value,
402                               unsigned TargetWidth) {
403  unsigned SourceWidth = value.getBitWidth();
404  llvm::APSInt truncated = value;
405  truncated.trunc(TargetWidth);
406  truncated.extend(SourceWidth);
407  return (truncated == value);
408}
409
410/// Checks whether the given value will have the same value if it
411/// is truncated to the given width, then extended back to the original
412/// width.
413///
414/// The value might be a vector or a complex.
415static bool IsSameIntAfterCast(const APValue &value, unsigned TargetWidth) {
416  if (value.isInt())
417    return IsSameIntAfterCast(value.getInt(), TargetWidth);
418
419  if (value.isVector()) {
420    for (unsigned i = 0, e = value.getVectorLength(); i != e; ++i)
421      if (!IsSameIntAfterCast(value.getVectorElt(i), TargetWidth))
422        return false;
423    return true;
424  }
425
426  if (value.isComplexInt()) {
427    return IsSameIntAfterCast(value.getComplexIntReal(), TargetWidth) &&
428           IsSameIntAfterCast(value.getComplexIntImag(), TargetWidth);
429  }
430
431  // This can happen with lossless casts to intptr_t of "based" lvalues.
432  // Assume it might use arbitrary bits.
433  assert(value.isLValue());
434  return false;
435}
436
437
438/// Checks whether the given value, which currently has the given
439/// source semantics, has the same value when coerced through the
440/// target semantics.
441static bool IsSameFloatAfterCast(const llvm::APFloat &value,
442                                 const llvm::fltSemantics &Src,
443                                 const llvm::fltSemantics &Tgt) {
444  llvm::APFloat truncated = value;
445
446  bool ignored;
447  truncated.convert(Src, llvm::APFloat::rmNearestTiesToEven, &ignored);
448  truncated.convert(Tgt, llvm::APFloat::rmNearestTiesToEven, &ignored);
449
450  return truncated.bitwiseIsEqual(value);
451}
452
453/// Checks whether the given value, which currently has the given
454/// source semantics, has the same value when coerced through the
455/// target semantics.
456///
457/// The value might be a vector of floats (or a complex number).
458static bool IsSameFloatAfterCast(const APValue &value,
459                                 const llvm::fltSemantics &Src,
460                                 const llvm::fltSemantics &Tgt) {
461  if (value.isFloat())
462    return IsSameFloatAfterCast(value.getFloat(), Src, Tgt);
463
464  if (value.isVector()) {
465    for (unsigned i = 0, e = value.getVectorLength(); i != e; ++i)
466      if (!IsSameFloatAfterCast(value.getVectorElt(i), Src, Tgt))
467        return false;
468    return true;
469  }
470
471  assert(value.isComplexFloat());
472  return (IsSameFloatAfterCast(value.getComplexFloatReal(), Src, Tgt) &&
473          IsSameFloatAfterCast(value.getComplexFloatImag(), Src, Tgt));
474}
475
476/// Determines if it's reasonable for the given expression to be truncated
477/// down to the given integer width.
478/// * Boolean expressions are automatically white-listed.
479/// * Arithmetic operations on implicitly-promoted operands of the
480///   target width or less are okay --- not because the results are
481///   actually guaranteed to fit within the width, but because the
482///   user is effectively pretending that the operations are closed
483///   within the implicitly-promoted type.
484static bool IsExprValueWithinWidth(ASTContext &C, Expr *E, unsigned Width) {
485  E = E->IgnoreParens();
486
487#ifndef NDEBUG
488  {
489    const Type *ETy = E->getType()->getCanonicalTypeInternal().getTypePtr();
490    unsigned EWidth;
491    bool ESigned;
492
493    if (!getIntProperties(C, ETy, EWidth, ESigned))
494      assert(0 && "expression not of integer type");
495
496    // The caller should never let this happen.
497    assert(EWidth > Width && "called on expr whose type is too small");
498  }
499#endif
500
501  // Strip implicit casts off.
502  while (isa<ImplicitCastExpr>(E)) {
503    E = cast<ImplicitCastExpr>(E)->getSubExpr();
504
505    const Type *ETy = E->getType()->getCanonicalTypeInternal().getTypePtr();
506
507    unsigned EWidth;
508    bool ESigned;
509    if (!getIntProperties(C, ETy, EWidth, ESigned))
510      return false;
511
512    if (EWidth <= Width)
513      return true;
514  }
515
516  if (BinaryOperator *BO = dyn_cast<BinaryOperator>(E)) {
517    switch (BO->getOpcode()) {
518
519    // Boolean-valued operations are white-listed.
520    case BinaryOperator::LAnd:
521    case BinaryOperator::LOr:
522    case BinaryOperator::LT:
523    case BinaryOperator::GT:
524    case BinaryOperator::LE:
525    case BinaryOperator::GE:
526    case BinaryOperator::EQ:
527    case BinaryOperator::NE:
528      return true;
529
530    // Operations with opaque sources are black-listed.
531    case BinaryOperator::PtrMemD:
532    case BinaryOperator::PtrMemI:
533      return false;
534
535    // Left shift gets black-listed based on a judgement call.
536    case BinaryOperator::Shl:
537      return false;
538
539    // Various special cases.
540    case BinaryOperator::Shr:
541      return IsExprValueWithinWidth(C, BO->getLHS(), Width);
542    case BinaryOperator::Comma:
543      return IsExprValueWithinWidth(C, BO->getRHS(), Width);
544    case BinaryOperator::Sub:
545      if (BO->getLHS()->getType()->isPointerType())
546        return false;
547      // fallthrough
548
549    // Any other operator is okay if the operands are
550    // promoted from expressions of appropriate size.
551    default:
552      return IsExprValueWithinWidth(C, BO->getLHS(), Width) &&
553             IsExprValueWithinWidth(C, BO->getRHS(), Width);
554    }
555  }
556
557  if (UnaryOperator *UO = dyn_cast<UnaryOperator>(E)) {
558    switch (UO->getOpcode()) {
559    // Boolean-valued operations are white-listed.
560    case UnaryOperator::LNot:
561      return true;
562
563    // Operations with opaque sources are black-listed.
564    case UnaryOperator::Deref:
565    case UnaryOperator::AddrOf: // should be impossible
566      return false;
567
568    case UnaryOperator::OffsetOf:
569      return false;
570
571    default:
572      return IsExprValueWithinWidth(C, UO->getSubExpr(), Width);
573    }
574  }
575
576  // Don't diagnose if the expression is an integer constant
577  // whose value in the target type is the same as it was
578  // in the original type.
579  Expr::EvalResult result;
580  if (E->Evaluate(result, C))
581    if (IsSameIntAfterCast(result.Val, Width))
582      return true;
583
584  return false;
585}
586
587/// Diagnose an implicit cast;  purely a helper for CheckImplicitConversion.
588static void DiagnoseImpCast(Sema &S, Expr *E, QualType T, unsigned diag) {
589  S.Diag(E->getExprLoc(), diag) << E->getType() << T << E->getSourceRange();
590}
591
592/// Implements -Wconversion.
593static void CheckImplicitConversion(Sema &S, Expr *E, QualType T) {
594  // Don't diagnose in unevaluated contexts.
595  if (S.ExprEvalContext == Sema::Unevaluated)
596    return;
597
598  // Don't diagnose for value-dependent expressions.
599  if (E->isValueDependent())
600    return;
601
602  const Type *Source = S.Context.getCanonicalType(E->getType()).getTypePtr();
603  const Type *Target = S.Context.getCanonicalType(T).getTypePtr();
604
605  // Never diagnose implicit casts to bool.
606  if (Target->isSpecificBuiltinType(BuiltinType::Bool))
607    return;
608
609  // Strip vector types.
610  if (isa<VectorType>(Source)) {
611    if (!isa<VectorType>(Target))
612      return DiagnoseImpCast(S, E, T, diag::warn_impcast_vector_scalar);
613
614    Source = cast<VectorType>(Source)->getElementType().getTypePtr();
615    Target = cast<VectorType>(Target)->getElementType().getTypePtr();
616  }
617
618  // Strip complex types.
619  if (isa<ComplexType>(Source)) {
620    if (!isa<ComplexType>(Target))
621      return DiagnoseImpCast(S, E, T, diag::warn_impcast_complex_scalar);
622
623    Source = cast<ComplexType>(Source)->getElementType().getTypePtr();
624    Target = cast<ComplexType>(Target)->getElementType().getTypePtr();
625  }
626
627  const BuiltinType *SourceBT = dyn_cast<BuiltinType>(Source);
628  const BuiltinType *TargetBT = dyn_cast<BuiltinType>(Target);
629
630  // If the source is floating point...
631  if (SourceBT && SourceBT->isFloatingPoint()) {
632    // ...and the target is floating point...
633    if (TargetBT && TargetBT->isFloatingPoint()) {
634      // ...then warn if we're dropping FP rank.
635
636      // Builtin FP kinds are ordered by increasing FP rank.
637      if (SourceBT->getKind() > TargetBT->getKind()) {
638        // Don't warn about float constants that are precisely
639        // representable in the target type.
640        Expr::EvalResult result;
641        if (E->Evaluate(result, S.Context)) {
642          // Value might be a float, a float vector, or a float complex.
643          if (IsSameFloatAfterCast(result.Val,
644                     S.Context.getFloatTypeSemantics(QualType(TargetBT, 0)),
645                     S.Context.getFloatTypeSemantics(QualType(SourceBT, 0))))
646            return;
647        }
648
649        DiagnoseImpCast(S, E, T, diag::warn_impcast_float_precision);
650      }
651      return;
652    }
653
654    // If the target is integral, always warn.
655    if ((TargetBT && TargetBT->isInteger()) ||
656        isa<FixedWidthIntType>(Target))
657      // TODO: don't warn for integer values?
658      return DiagnoseImpCast(S, E, T, diag::warn_impcast_float_integer);
659
660    return;
661  }
662
663  unsigned SourceWidth, TargetWidth;
664  bool SourceSigned, TargetSigned;
665
666  if (!getIntProperties(S.Context, Source, SourceWidth, SourceSigned) ||
667      !getIntProperties(S.Context, Target, TargetWidth, TargetSigned))
668    return;
669
670  if (SourceWidth > TargetWidth) {
671    if (IsExprValueWithinWidth(S.Context, E, TargetWidth))
672      return;
673
674    // People want to build with -Wshorten-64-to-32 and not -Wconversion
675    // and by god we'll let them.
676    if (SourceWidth == 64 && TargetWidth == 32)
677      return DiagnoseImpCast(S, E, T, diag::warn_impcast_integer_64_32);
678    return DiagnoseImpCast(S, E, T, diag::warn_impcast_integer_precision);
679  }
680
681  return;
682}
683
684/// ImpCastExprToType - If Expr is not of type 'Type', insert an implicit cast.
685/// If there is already an implicit cast, merge into the existing one.
686/// If isLvalue, the result of the cast is an lvalue.
687void Sema::ImpCastExprToType(Expr *&Expr, QualType Ty,
688                             CastExpr::CastKind Kind, bool isLvalue) {
689  QualType ExprTy = Context.getCanonicalType(Expr->getType());
690  QualType TypeTy = Context.getCanonicalType(Ty);
691
692  if (ExprTy == TypeTy)
693    return;
694
695  if (Expr->getType()->isPointerType() && Ty->isPointerType()) {
696    QualType ExprBaseType = cast<PointerType>(ExprTy)->getPointeeType();
697    QualType BaseType = cast<PointerType>(TypeTy)->getPointeeType();
698    if (ExprBaseType.getAddressSpace() != BaseType.getAddressSpace()) {
699      Diag(Expr->getExprLoc(), diag::err_implicit_pointer_address_space_cast)
700        << Expr->getSourceRange();
701    }
702  }
703
704  CheckImplicitConversion(*this, Expr, Ty);
705
706  if (ImplicitCastExpr *ImpCast = dyn_cast<ImplicitCastExpr>(Expr)) {
707    if (ImpCast->getCastKind() == Kind) {
708      ImpCast->setType(Ty);
709      ImpCast->setLvalueCast(isLvalue);
710      return;
711    }
712  }
713
714  Expr = new (Context) ImplicitCastExpr(Ty, Kind, Expr, isLvalue);
715}
716
717void Sema::DeleteExpr(ExprTy *E) {
718  if (E) static_cast<Expr*>(E)->Destroy(Context);
719}
720void Sema::DeleteStmt(StmtTy *S) {
721  if (S) static_cast<Stmt*>(S)->Destroy(Context);
722}
723
724/// ActOnEndOfTranslationUnit - This is called at the very end of the
725/// translation unit when EOF is reached and all but the top-level scope is
726/// popped.
727void Sema::ActOnEndOfTranslationUnit() {
728  // C++: Perform implicit template instantiations.
729  //
730  // FIXME: When we perform these implicit instantiations, we do not carefully
731  // keep track of the point of instantiation (C++ [temp.point]). This means
732  // that name lookup that occurs within the template instantiation will
733  // always happen at the end of the translation unit, so it will find
734  // some names that should not be found. Although this is common behavior
735  // for C++ compilers, it is technically wrong. In the future, we either need
736  // to be able to filter the results of name lookup or we need to perform
737  // template instantiations earlier.
738  PerformPendingImplicitInstantiations();
739
740  // Check for #pragma weak identifiers that were never declared
741  // FIXME: This will cause diagnostics to be emitted in a non-determinstic
742  // order!  Iterating over a densemap like this is bad.
743  for (llvm::DenseMap<IdentifierInfo*,WeakInfo>::iterator
744       I = WeakUndeclaredIdentifiers.begin(),
745       E = WeakUndeclaredIdentifiers.end(); I != E; ++I) {
746    if (I->second.getUsed()) continue;
747
748    Diag(I->second.getLocation(), diag::warn_weak_identifier_undeclared)
749      << I->first;
750  }
751
752  if (!CompleteTranslationUnit)
753    return;
754
755  // C99 6.9.2p2:
756  //   A declaration of an identifier for an object that has file
757  //   scope without an initializer, and without a storage-class
758  //   specifier or with the storage-class specifier static,
759  //   constitutes a tentative definition. If a translation unit
760  //   contains one or more tentative definitions for an identifier,
761  //   and the translation unit contains no external definition for
762  //   that identifier, then the behavior is exactly as if the
763  //   translation unit contains a file scope declaration of that
764  //   identifier, with the composite type as of the end of the
765  //   translation unit, with an initializer equal to 0.
766  for (unsigned i = 0, e = TentativeDefinitionList.size(); i != e; ++i) {
767    VarDecl *VD = TentativeDefinitions.lookup(TentativeDefinitionList[i]);
768
769    // If the tentative definition was completed, it will be in the list, but
770    // not the map.
771    if (VD == 0 || VD->isInvalidDecl() || !VD->isTentativeDefinition(Context))
772      continue;
773
774    if (const IncompleteArrayType *ArrayT
775        = Context.getAsIncompleteArrayType(VD->getType())) {
776      if (RequireCompleteType(VD->getLocation(),
777                              ArrayT->getElementType(),
778                              diag::err_tentative_def_incomplete_type_arr)) {
779        VD->setInvalidDecl();
780        continue;
781      }
782
783      // Set the length of the array to 1 (C99 6.9.2p5).
784      Diag(VD->getLocation(), diag::warn_tentative_incomplete_array);
785      llvm::APInt One(Context.getTypeSize(Context.getSizeType()), true);
786      QualType T = Context.getConstantArrayType(ArrayT->getElementType(),
787                                                One, ArrayType::Normal, 0);
788      VD->setType(T);
789    } else if (RequireCompleteType(VD->getLocation(), VD->getType(),
790                                   diag::err_tentative_def_incomplete_type))
791      VD->setInvalidDecl();
792
793    // Notify the consumer that we've completed a tentative definition.
794    if (!VD->isInvalidDecl())
795      Consumer.CompleteTentativeDefinition(VD);
796
797  }
798}
799
800
801//===----------------------------------------------------------------------===//
802// Helper functions.
803//===----------------------------------------------------------------------===//
804
805DeclContext *Sema::getFunctionLevelDeclContext() {
806  DeclContext *DC = PreDeclaratorDC ? PreDeclaratorDC : CurContext;
807
808  while (isa<BlockDecl>(DC))
809    DC = DC->getParent();
810
811  return DC;
812}
813
814/// getCurFunctionDecl - If inside of a function body, this returns a pointer
815/// to the function decl for the function being parsed.  If we're currently
816/// in a 'block', this returns the containing context.
817FunctionDecl *Sema::getCurFunctionDecl() {
818  DeclContext *DC = getFunctionLevelDeclContext();
819  return dyn_cast<FunctionDecl>(DC);
820}
821
822ObjCMethodDecl *Sema::getCurMethodDecl() {
823  DeclContext *DC = getFunctionLevelDeclContext();
824  return dyn_cast<ObjCMethodDecl>(DC);
825}
826
827NamedDecl *Sema::getCurFunctionOrMethodDecl() {
828  DeclContext *DC = getFunctionLevelDeclContext();
829  if (isa<ObjCMethodDecl>(DC) || isa<FunctionDecl>(DC))
830    return cast<NamedDecl>(DC);
831  return 0;
832}
833
834Sema::SemaDiagnosticBuilder::~SemaDiagnosticBuilder() {
835  if (!this->Emit())
836    return;
837
838  // If this is not a note, and we're in a template instantiation
839  // that is different from the last template instantiation where
840  // we emitted an error, print a template instantiation
841  // backtrace.
842  if (!SemaRef.Diags.isBuiltinNote(DiagID) &&
843      !SemaRef.ActiveTemplateInstantiations.empty() &&
844      SemaRef.ActiveTemplateInstantiations.back()
845        != SemaRef.LastTemplateInstantiationErrorContext) {
846    SemaRef.PrintInstantiationStack();
847    SemaRef.LastTemplateInstantiationErrorContext
848      = SemaRef.ActiveTemplateInstantiations.back();
849  }
850}
851
852Sema::SemaDiagnosticBuilder
853Sema::Diag(SourceLocation Loc, const PartialDiagnostic& PD) {
854  SemaDiagnosticBuilder Builder(Diag(Loc, PD.getDiagID()));
855  PD.Emit(Builder);
856
857  return Builder;
858}
859
860void Sema::ActOnComment(SourceRange Comment) {
861  Context.Comments.push_back(Comment);
862}
863
864