Sema.cpp revision 79f414435ef406f9fb3dc7733b93715ac6313425 
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    TypeSourceInfo *TInfo;
282
283    // Install [u]int128_t for 64-bit targets.
284    TInfo = Context.getTrivialTypeSourceInfo(Context.Int128Ty);
285    PushOnScopeChains(TypedefDecl::Create(Context, CurContext,
286                                          SourceLocation(),
287                                          &Context.Idents.get("__int128_t"),
288                                          TInfo), TUScope);
289
290    TInfo = Context.getTrivialTypeSourceInfo(Context.UnsignedInt128Ty);
291    PushOnScopeChains(TypedefDecl::Create(Context, CurContext,
292                                          SourceLocation(),
293                                          &Context.Idents.get("__uint128_t"),
294                                          TInfo), 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.getPointerType(Context.ObjCBuiltinSelTy);
304    TypeSourceInfo *SelInfo = Context.getTrivialTypeSourceInfo(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    TypeSourceInfo *IdInfo = Context.getTrivialTypeSourceInfo(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    TypeSourceInfo *ClassInfo = Context.getTrivialTypeSourceInfo(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    CurBlock(0), PackContext(0), ParsingDeclDepth(0),
354    IdResolver(pp.getLangOptions()), StdNamespace(0), StdBadAlloc(0),
355    GlobalNewDeleteDeclared(false),
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  ExprEvalContexts.push_back(
368                  ExpressionEvaluationContextRecord(PotentiallyEvaluated, 0));
369}
370
371/// Retrieves the width and signedness of the given integer type,
372/// or returns false if it is not an integer type.
373///
374/// \param T must be canonical
375static bool getIntProperties(ASTContext &C, const Type *T,
376                             unsigned &BitWidth, bool &Signed) {
377  assert(T->isCanonicalUnqualified());
378
379  if (const VectorType *VT = dyn_cast<VectorType>(T))
380    T = VT->getElementType().getTypePtr();
381  if (const ComplexType *CT = dyn_cast<ComplexType>(T))
382    T = CT->getElementType().getTypePtr();
383
384  if (const BuiltinType *BT = dyn_cast<BuiltinType>(T)) {
385    if (!BT->isInteger()) return false;
386
387    BitWidth = C.getIntWidth(QualType(T, 0));
388    Signed = BT->isSignedInteger();
389    return true;
390  }
391
392  return false;
393}
394
395/// Checks whether the given value will have the same value if it it
396/// is truncated to the given width, then extended back to the
397/// original width.
398static bool IsSameIntAfterCast(const llvm::APSInt &value,
399                               unsigned TargetWidth) {
400  unsigned SourceWidth = value.getBitWidth();
401  llvm::APSInt truncated = value;
402  truncated.trunc(TargetWidth);
403  truncated.extend(SourceWidth);
404  return (truncated == value);
405}
406
407/// Checks whether the given value will have the same value if it
408/// is truncated to the given width, then extended back to the original
409/// width.
410///
411/// The value might be a vector or a complex.
412static bool IsSameIntAfterCast(const APValue &value, unsigned TargetWidth) {
413  if (value.isInt())
414    return IsSameIntAfterCast(value.getInt(), TargetWidth);
415
416  if (value.isVector()) {
417    for (unsigned i = 0, e = value.getVectorLength(); i != e; ++i)
418      if (!IsSameIntAfterCast(value.getVectorElt(i), TargetWidth))
419        return false;
420    return true;
421  }
422
423  if (value.isComplexInt()) {
424    return IsSameIntAfterCast(value.getComplexIntReal(), TargetWidth) &&
425           IsSameIntAfterCast(value.getComplexIntImag(), TargetWidth);
426  }
427
428  // This can happen with lossless casts to intptr_t of "based" lvalues.
429  // Assume it might use arbitrary bits.
430  assert(value.isLValue());
431  return false;
432}
433
434
435/// Checks whether the given value, which currently has the given
436/// source semantics, has the same value when coerced through the
437/// target semantics.
438static bool IsSameFloatAfterCast(const llvm::APFloat &value,
439                                 const llvm::fltSemantics &Src,
440                                 const llvm::fltSemantics &Tgt) {
441  llvm::APFloat truncated = value;
442
443  bool ignored;
444  truncated.convert(Src, llvm::APFloat::rmNearestTiesToEven, &ignored);
445  truncated.convert(Tgt, llvm::APFloat::rmNearestTiesToEven, &ignored);
446
447  return truncated.bitwiseIsEqual(value);
448}
449
450/// Checks whether the given value, which currently has the given
451/// source semantics, has the same value when coerced through the
452/// target semantics.
453///
454/// The value might be a vector of floats (or a complex number).
455static bool IsSameFloatAfterCast(const APValue &value,
456                                 const llvm::fltSemantics &Src,
457                                 const llvm::fltSemantics &Tgt) {
458  if (value.isFloat())
459    return IsSameFloatAfterCast(value.getFloat(), Src, Tgt);
460
461  if (value.isVector()) {
462    for (unsigned i = 0, e = value.getVectorLength(); i != e; ++i)
463      if (!IsSameFloatAfterCast(value.getVectorElt(i), Src, Tgt))
464        return false;
465    return true;
466  }
467
468  assert(value.isComplexFloat());
469  return (IsSameFloatAfterCast(value.getComplexFloatReal(), Src, Tgt) &&
470          IsSameFloatAfterCast(value.getComplexFloatImag(), Src, Tgt));
471}
472
473/// Determines if it's reasonable for the given expression to be truncated
474/// down to the given integer width.
475/// * Boolean expressions are automatically white-listed.
476/// * Arithmetic operations on implicitly-promoted operands of the
477///   target width or less are okay --- not because the results are
478///   actually guaranteed to fit within the width, but because the
479///   user is effectively pretending that the operations are closed
480///   within the implicitly-promoted type.
481static bool IsExprValueWithinWidth(ASTContext &C, Expr *E, unsigned Width) {
482  E = E->IgnoreParens();
483
484#ifndef NDEBUG
485  {
486    const Type *ETy = E->getType()->getCanonicalTypeInternal().getTypePtr();
487    unsigned EWidth;
488    bool ESigned;
489
490    if (!getIntProperties(C, ETy, EWidth, ESigned))
491      assert(0 && "expression not of integer type");
492
493    // The caller should never let this happen.
494    assert(EWidth > Width && "called on expr whose type is too small");
495  }
496#endif
497
498  // Strip implicit casts off.
499  while (isa<ImplicitCastExpr>(E)) {
500    E = cast<ImplicitCastExpr>(E)->getSubExpr();
501
502    const Type *ETy = E->getType()->getCanonicalTypeInternal().getTypePtr();
503
504    unsigned EWidth;
505    bool ESigned;
506    if (!getIntProperties(C, ETy, EWidth, ESigned))
507      return false;
508
509    if (EWidth <= Width)
510      return true;
511  }
512
513  if (BinaryOperator *BO = dyn_cast<BinaryOperator>(E)) {
514    switch (BO->getOpcode()) {
515
516    // Boolean-valued operations are white-listed.
517    case BinaryOperator::LAnd:
518    case BinaryOperator::LOr:
519    case BinaryOperator::LT:
520    case BinaryOperator::GT:
521    case BinaryOperator::LE:
522    case BinaryOperator::GE:
523    case BinaryOperator::EQ:
524    case BinaryOperator::NE:
525      return true;
526
527    // Operations with opaque sources are black-listed.
528    case BinaryOperator::PtrMemD:
529    case BinaryOperator::PtrMemI:
530      return false;
531
532    // Left shift gets black-listed based on a judgement call.
533    case BinaryOperator::Shl:
534      return false;
535
536    // Various special cases.
537    case BinaryOperator::Shr:
538      return IsExprValueWithinWidth(C, BO->getLHS(), Width);
539    case BinaryOperator::Comma:
540      return IsExprValueWithinWidth(C, BO->getRHS(), Width);
541    case BinaryOperator::Sub:
542      if (BO->getLHS()->getType()->isPointerType())
543        return false;
544      // fallthrough
545
546    // Any other operator is okay if the operands are
547    // promoted from expressions of appropriate size.
548    default:
549      return IsExprValueWithinWidth(C, BO->getLHS(), Width) &&
550             IsExprValueWithinWidth(C, BO->getRHS(), Width);
551    }
552  }
553
554  if (UnaryOperator *UO = dyn_cast<UnaryOperator>(E)) {
555    switch (UO->getOpcode()) {
556    // Boolean-valued operations are white-listed.
557    case UnaryOperator::LNot:
558      return true;
559
560    // Operations with opaque sources are black-listed.
561    case UnaryOperator::Deref:
562    case UnaryOperator::AddrOf: // should be impossible
563      return false;
564
565    case UnaryOperator::OffsetOf:
566      return false;
567
568    default:
569      return IsExprValueWithinWidth(C, UO->getSubExpr(), Width);
570    }
571  }
572
573  // Don't diagnose if the expression is an integer constant
574  // whose value in the target type is the same as it was
575  // in the original type.
576  Expr::EvalResult result;
577  if (E->Evaluate(result, C))
578    if (IsSameIntAfterCast(result.Val, Width))
579      return true;
580
581  return false;
582}
583
584/// Diagnose an implicit cast;  purely a helper for CheckImplicitConversion.
585static void DiagnoseImpCast(Sema &S, Expr *E, QualType T, unsigned diag) {
586  S.Diag(E->getExprLoc(), diag) << E->getType() << T << E->getSourceRange();
587}
588
589/// Implements -Wconversion.
590static void CheckImplicitConversion(Sema &S, Expr *E, QualType T) {
591  // Don't diagnose in unevaluated contexts.
592  if (S.ExprEvalContexts.back().Context == Sema::Unevaluated)
593    return;
594
595  // Don't diagnose for value-dependent expressions.
596  if (E->isValueDependent())
597    return;
598
599  const Type *Source = S.Context.getCanonicalType(E->getType()).getTypePtr();
600  const Type *Target = S.Context.getCanonicalType(T).getTypePtr();
601
602  // Never diagnose implicit casts to bool.
603  if (Target->isSpecificBuiltinType(BuiltinType::Bool))
604    return;
605
606  // Strip vector types.
607  if (isa<VectorType>(Source)) {
608    if (!isa<VectorType>(Target))
609      return DiagnoseImpCast(S, E, T, diag::warn_impcast_vector_scalar);
610
611    Source = cast<VectorType>(Source)->getElementType().getTypePtr();
612    Target = cast<VectorType>(Target)->getElementType().getTypePtr();
613  }
614
615  // Strip complex types.
616  if (isa<ComplexType>(Source)) {
617    if (!isa<ComplexType>(Target))
618      return DiagnoseImpCast(S, E, T, diag::warn_impcast_complex_scalar);
619
620    Source = cast<ComplexType>(Source)->getElementType().getTypePtr();
621    Target = cast<ComplexType>(Target)->getElementType().getTypePtr();
622  }
623
624  const BuiltinType *SourceBT = dyn_cast<BuiltinType>(Source);
625  const BuiltinType *TargetBT = dyn_cast<BuiltinType>(Target);
626
627  // If the source is floating point...
628  if (SourceBT && SourceBT->isFloatingPoint()) {
629    // ...and the target is floating point...
630    if (TargetBT && TargetBT->isFloatingPoint()) {
631      // ...then warn if we're dropping FP rank.
632
633      // Builtin FP kinds are ordered by increasing FP rank.
634      if (SourceBT->getKind() > TargetBT->getKind()) {
635        // Don't warn about float constants that are precisely
636        // representable in the target type.
637        Expr::EvalResult result;
638        if (E->Evaluate(result, S.Context)) {
639          // Value might be a float, a float vector, or a float complex.
640          if (IsSameFloatAfterCast(result.Val,
641                     S.Context.getFloatTypeSemantics(QualType(TargetBT, 0)),
642                     S.Context.getFloatTypeSemantics(QualType(SourceBT, 0))))
643            return;
644        }
645
646        DiagnoseImpCast(S, E, T, diag::warn_impcast_float_precision);
647      }
648      return;
649    }
650
651    // If the target is integral, always warn.
652    if ((TargetBT && TargetBT->isInteger()))
653      // TODO: don't warn for integer values?
654      return DiagnoseImpCast(S, E, T, diag::warn_impcast_float_integer);
655
656    return;
657  }
658
659  unsigned SourceWidth, TargetWidth;
660  bool SourceSigned, TargetSigned;
661
662  if (!getIntProperties(S.Context, Source, SourceWidth, SourceSigned) ||
663      !getIntProperties(S.Context, Target, TargetWidth, TargetSigned))
664    return;
665
666  if (SourceWidth > TargetWidth) {
667    if (IsExprValueWithinWidth(S.Context, E, TargetWidth))
668      return;
669
670    // People want to build with -Wshorten-64-to-32 and not -Wconversion
671    // and by god we'll let them.
672    if (SourceWidth == 64 && TargetWidth == 32)
673      return DiagnoseImpCast(S, E, T, diag::warn_impcast_integer_64_32);
674    return DiagnoseImpCast(S, E, T, diag::warn_impcast_integer_precision);
675  }
676
677  return;
678}
679
680/// ImpCastExprToType - If Expr is not of type 'Type', insert an implicit cast.
681/// If there is already an implicit cast, merge into the existing one.
682/// If isLvalue, the result of the cast is an lvalue.
683void Sema::ImpCastExprToType(Expr *&Expr, QualType Ty,
684                             CastExpr::CastKind Kind, bool isLvalue) {
685  QualType ExprTy = Context.getCanonicalType(Expr->getType());
686  QualType TypeTy = Context.getCanonicalType(Ty);
687
688  if (ExprTy == TypeTy)
689    return;
690
691  if (Expr->getType()->isPointerType() && Ty->isPointerType()) {
692    QualType ExprBaseType = cast<PointerType>(ExprTy)->getPointeeType();
693    QualType BaseType = cast<PointerType>(TypeTy)->getPointeeType();
694    if (ExprBaseType.getAddressSpace() != BaseType.getAddressSpace()) {
695      Diag(Expr->getExprLoc(), diag::err_implicit_pointer_address_space_cast)
696        << Expr->getSourceRange();
697    }
698  }
699
700  CheckImplicitConversion(*this, Expr, Ty);
701
702  if (ImplicitCastExpr *ImpCast = dyn_cast<ImplicitCastExpr>(Expr)) {
703    if (ImpCast->getCastKind() == Kind) {
704      ImpCast->setType(Ty);
705      ImpCast->setLvalueCast(isLvalue);
706      return;
707    }
708  }
709
710  Expr = new (Context) ImplicitCastExpr(Ty, Kind, Expr, isLvalue);
711}
712
713void Sema::DeleteExpr(ExprTy *E) {
714  if (E) static_cast<Expr*>(E)->Destroy(Context);
715}
716void Sema::DeleteStmt(StmtTy *S) {
717  if (S) static_cast<Stmt*>(S)->Destroy(Context);
718}
719
720/// ActOnEndOfTranslationUnit - This is called at the very end of the
721/// translation unit when EOF is reached and all but the top-level scope is
722/// popped.
723void Sema::ActOnEndOfTranslationUnit() {
724
725  while (1) {
726    // C++: Perform implicit template instantiations.
727    //
728    // FIXME: When we perform these implicit instantiations, we do not carefully
729    // keep track of the point of instantiation (C++ [temp.point]). This means
730    // that name lookup that occurs within the template instantiation will
731    // always happen at the end of the translation unit, so it will find
732    // some names that should not be found. Although this is common behavior
733    // for C++ compilers, it is technically wrong. In the future, we either need
734    // to be able to filter the results of name lookup or we need to perform
735    // template instantiations earlier.
736    PerformPendingImplicitInstantiations();
737
738    /// If ProcessPendingClassesWithUnmarkedVirtualMembers ends up marking
739    /// any virtual member functions it might lead to more pending template
740    /// instantiations, which is why we need to loop here.
741    if (!ProcessPendingClassesWithUnmarkedVirtualMembers())
742      break;
743  }
744
745  // Check for #pragma weak identifiers that were never declared
746  // FIXME: This will cause diagnostics to be emitted in a non-determinstic
747  // order!  Iterating over a densemap like this is bad.
748  for (llvm::DenseMap<IdentifierInfo*,WeakInfo>::iterator
749       I = WeakUndeclaredIdentifiers.begin(),
750       E = WeakUndeclaredIdentifiers.end(); I != E; ++I) {
751    if (I->second.getUsed()) continue;
752
753    Diag(I->second.getLocation(), diag::warn_weak_identifier_undeclared)
754      << I->first;
755  }
756
757  if (!CompleteTranslationUnit)
758    return;
759
760  // C99 6.9.2p2:
761  //   A declaration of an identifier for an object that has file
762  //   scope without an initializer, and without a storage-class
763  //   specifier or with the storage-class specifier static,
764  //   constitutes a tentative definition. If a translation unit
765  //   contains one or more tentative definitions for an identifier,
766  //   and the translation unit contains no external definition for
767  //   that identifier, then the behavior is exactly as if the
768  //   translation unit contains a file scope declaration of that
769  //   identifier, with the composite type as of the end of the
770  //   translation unit, with an initializer equal to 0.
771  for (unsigned i = 0, e = TentativeDefinitionList.size(); i != e; ++i) {
772    VarDecl *VD = TentativeDefinitions.lookup(TentativeDefinitionList[i]);
773
774    // If the tentative definition was completed, it will be in the list, but
775    // not the map.
776    if (VD == 0 || VD->isInvalidDecl() || !VD->isTentativeDefinition(Context))
777      continue;
778
779    if (const IncompleteArrayType *ArrayT
780        = Context.getAsIncompleteArrayType(VD->getType())) {
781      if (RequireCompleteType(VD->getLocation(),
782                              ArrayT->getElementType(),
783                              diag::err_tentative_def_incomplete_type_arr)) {
784        VD->setInvalidDecl();
785        continue;
786      }
787
788      // Set the length of the array to 1 (C99 6.9.2p5).
789      Diag(VD->getLocation(), diag::warn_tentative_incomplete_array);
790      llvm::APInt One(Context.getTypeSize(Context.getSizeType()), true);
791      QualType T = Context.getConstantArrayType(ArrayT->getElementType(),
792                                                One, ArrayType::Normal, 0);
793      VD->setType(T);
794    } else if (RequireCompleteType(VD->getLocation(), VD->getType(),
795                                   diag::err_tentative_def_incomplete_type))
796      VD->setInvalidDecl();
797
798    // Notify the consumer that we've completed a tentative definition.
799    if (!VD->isInvalidDecl())
800      Consumer.CompleteTentativeDefinition(VD);
801
802  }
803}
804
805
806//===----------------------------------------------------------------------===//
807// Helper functions.
808//===----------------------------------------------------------------------===//
809
810DeclContext *Sema::getFunctionLevelDeclContext() {
811  DeclContext *DC = CurContext;
812
813  while (isa<BlockDecl>(DC))
814    DC = DC->getParent();
815
816  return DC;
817}
818
819/// getCurFunctionDecl - If inside of a function body, this returns a pointer
820/// to the function decl for the function being parsed.  If we're currently
821/// in a 'block', this returns the containing context.
822FunctionDecl *Sema::getCurFunctionDecl() {
823  DeclContext *DC = getFunctionLevelDeclContext();
824  return dyn_cast<FunctionDecl>(DC);
825}
826
827ObjCMethodDecl *Sema::getCurMethodDecl() {
828  DeclContext *DC = getFunctionLevelDeclContext();
829  return dyn_cast<ObjCMethodDecl>(DC);
830}
831
832NamedDecl *Sema::getCurFunctionOrMethodDecl() {
833  DeclContext *DC = getFunctionLevelDeclContext();
834  if (isa<ObjCMethodDecl>(DC) || isa<FunctionDecl>(DC))
835    return cast<NamedDecl>(DC);
836  return 0;
837}
838
839Sema::SemaDiagnosticBuilder::~SemaDiagnosticBuilder() {
840  if (!this->Emit())
841    return;
842
843  // If this is not a note, and we're in a template instantiation
844  // that is different from the last template instantiation where
845  // we emitted an error, print a template instantiation
846  // backtrace.
847  if (!SemaRef.Diags.isBuiltinNote(DiagID) &&
848      !SemaRef.ActiveTemplateInstantiations.empty() &&
849      SemaRef.ActiveTemplateInstantiations.back()
850        != SemaRef.LastTemplateInstantiationErrorContext) {
851    SemaRef.PrintInstantiationStack();
852    SemaRef.LastTemplateInstantiationErrorContext
853      = SemaRef.ActiveTemplateInstantiations.back();
854  }
855}
856
857Sema::SemaDiagnosticBuilder
858Sema::Diag(SourceLocation Loc, const PartialDiagnostic& PD) {
859  SemaDiagnosticBuilder Builder(Diag(Loc, PD.getDiagID()));
860  PD.Emit(Builder);
861
862  return Builder;
863}
864
865void Sema::ActOnComment(SourceRange Comment) {
866  Context.Comments.push_back(Comment);
867}
868
869