C++ Sema::DefaultFunctionArrayConversion方法代码示例

/// CheckReinterpretCast - Check that a reinterpret_cast\<DestType\>(SrcExpr) is
/// valid.
/// Refer to C++ 5.2.10 for details. reinterpret_cast is typically used in code
/// like this:
/// char *bytes = reinterpret_cast\<char*\>(int_ptr);
void
CheckReinterpretCast(Sema &Self, Expr *&SrcExpr, QualType DestType,
                     const SourceRange &OpRange, const SourceRange &DestRange)
{
  if (!DestType->isLValueReferenceType())
    Self.DefaultFunctionArrayConversion(SrcExpr);

  unsigned msg = diag::err_bad_cxx_cast_generic;
  if (TryReinterpretCast(Self, SrcExpr, DestType, /*CStyle*/false, OpRange, msg)
      != TC_Success && msg != 0)
    Self.Diag(OpRange.getBegin(), msg) << CT_Reinterpret
      << SrcExpr->getType() << DestType << OpRange;
}

/// CheckStaticCast - Check that a static_cast\<DestType\>(SrcExpr) is valid.
/// Refer to C++ 5.2.9 for details. Static casts are mostly used for making
/// implicit conversions explicit and getting rid of data loss warnings.
void
CheckStaticCast(Sema &Self, Expr *&SrcExpr, QualType DestType,
                const SourceRange &OpRange)
{
  // The order the tests is not entirely arbitrary. There is one conversion
  // that can be handled in two different ways. Given:
  // struct A {};
  // struct B : public A {
  //   B(); B(const A&);
  // };
  // const A &a = B();
  // the cast static_cast<const B&>(a) could be seen as either a static
  // reference downcast, or an explicit invocation of the user-defined
  // conversion using B's conversion constructor.
  // DR 427 specifies that the downcast is to be applied here.

  // FIXME: With N2812, casts to rvalue refs will change.

  // C++ 5.2.9p4: Any expression can be explicitly converted to type "cv void".
  if (DestType->isVoidType()) {
    return;
  }

  // C++ 5.2.9p5, reference downcast.
  // See the function for details.
  // DR 427 specifies that this is to be applied before paragraph 2.
  if (TryStaticReferenceDowncast(Self, SrcExpr, DestType, OpRange)
      > TSC_NotApplicable) {
    return;
  }

  // N2844 5.2.9p3: An lvalue of type "cv1 T1" can be cast to type "rvalue
  //   reference to cv2 T2" if "cv2 T2" is reference-compatible with "cv1 T1".
  if (TryLValueToRValueCast(Self, SrcExpr, DestType, OpRange) >
      TSC_NotApplicable) {
    return;
  }

  // C++ 5.2.9p2: An expression e can be explicitly converted to a type T
  //   [...] if the declaration "T t(e);" is well-formed, [...].
  if (TryStaticImplicitCast(Self, SrcExpr, DestType, OpRange) >
      TSC_NotApplicable) {
    return;
  }

  // C++ 5.2.9p6: May apply the reverse of any standard conversion, except
  // lvalue-to-rvalue, array-to-pointer, function-to-pointer, and boolean
  // conversions, subject to further restrictions.
  // Also, C++ 5.2.9p1 forbids casting away constness, which makes reversal
  // of qualification conversions impossible.

  // The lvalue-to-rvalue, array-to-pointer and function-to-pointer conversions
  // are applied to the expression.
  QualType OrigSrcType = SrcExpr->getType();
  Self.DefaultFunctionArrayConversion(SrcExpr);

  QualType SrcType = Self.Context.getCanonicalType(SrcExpr->getType());

  // Reverse integral promotion/conversion. All such conversions are themselves
  // again integral promotions or conversions and are thus already handled by
  // p2 (TryDirectInitialization above).
  // (Note: any data loss warnings should be suppressed.)
  // The exception is the reverse of enum->integer, i.e. integer->enum (and
  // enum->enum). See also C++ 5.2.9p7.
  // The same goes for reverse floating point promotion/conversion and
  // floating-integral conversions. Again, only floating->enum is relevant.
  if (DestType->isEnumeralType()) {
    if (SrcType->isComplexType() || SrcType->isVectorType()) {
      // Fall through - these cannot be converted.
    } else if (SrcType->isArithmeticType() || SrcType->isEnumeralType()) {
      return;
    }
  }

  // Reverse pointer upcast. C++ 4.10p3 specifies pointer upcast.
  // C++ 5.2.9p8 additionally disallows a cast path through virtual inheritance.
  if (TryStaticPointerDowncast(Self, SrcType, DestType, OpRange)
      > TSC_NotApplicable) {
    return;
  }

  // Reverse member pointer conversion. C++ 4.11 specifies member pointer
  // conversion. C++ 5.2.9p9 has additional information.
  // DR54's access restrictions apply here also.
  if (TryStaticMemberPointerUpcast(Self, SrcType, DestType, OpRange)
      > TSC_NotApplicable) {
    return;
  }

  // Reverse pointer conversion to void*. C++ 4.10.p2 specifies conversion to
  // void*. C++ 5.2.9p10 specifies additional restrictions, which really is
  // just the usual constness stuff.
  if (const PointerType *SrcPointer = SrcType->getAsPointerType()) {
    QualType SrcPointee = SrcPointer->getPointeeType();
    if (SrcPointee->isVoidType()) {
      if (const PointerType *DestPointer = DestType->getAsPointerType()) {
        QualType DestPointee = DestPointer->getPointeeType();
//.........这里部分代码省略.........

/// CheckConstCast - Check that a const_cast\<DestType\>(SrcExpr) is valid.
/// Refer to C++ 5.2.11 for details. const_cast is typically used in code
/// like this:
/// const char *str = "literal";
/// legacy_function(const_cast\<char*\>(str));
void
CheckConstCast(Sema &Self, Expr *&SrcExpr, QualType DestType,
               const SourceRange &OpRange, const SourceRange &DestRange)
{
  QualType OrigDestType = DestType, OrigSrcType = SrcExpr->getType();

  DestType = Self.Context.getCanonicalType(DestType);
  QualType SrcType = SrcExpr->getType();
  if (const LValueReferenceType *DestTypeTmp =
        DestType->getAsLValueReferenceType()) {
    if (SrcExpr->isLvalue(Self.Context) != Expr::LV_Valid) {
      // Cannot cast non-lvalue to lvalue reference type.
      Self.Diag(OpRange.getBegin(), diag::err_bad_cxx_cast_rvalue)
        << "const_cast" << OrigDestType << SrcExpr->getSourceRange();
      return;
    }

    // C++ 5.2.11p4: An lvalue of type T1 can be [cast] to an lvalue of type T2
    //   [...] if a pointer to T1 can be [cast] to the type pointer to T2.
    DestType = Self.Context.getPointerType(DestTypeTmp->getPointeeType());
    SrcType = Self.Context.getPointerType(SrcType);
  } else {
    // C++ 5.2.11p1: Otherwise, the result is an rvalue and the
    //   lvalue-to-rvalue, array-to-pointer, and function-to-pointer standard
    //   conversions are performed on the expression.
    Self.DefaultFunctionArrayConversion(SrcExpr);
    SrcType = SrcExpr->getType();
  }

  // C++ 5.2.11p5: For a const_cast involving pointers to data members [...]
  //   the rules for const_cast are the same as those used for pointers.

  if (!DestType->isPointerType() && !DestType->isMemberPointerType()) {
    // Cannot cast to non-pointer, non-reference type. Note that, if DestType
    // was a reference type, we converted it to a pointer above.
    // The status of rvalue references isn't entirely clear, but it looks like
    // conversion to them is simply invalid.
    // C++ 5.2.11p3: For two pointer types [...]
    Self.Diag(OpRange.getBegin(), diag::err_bad_const_cast_dest)
      << OrigDestType << DestRange;
    return;
  }
  if (DestType->isFunctionPointerType() ||
      DestType->isMemberFunctionPointerType()) {
    // Cannot cast direct function pointers.
    // C++ 5.2.11p2: [...] where T is any object type or the void type [...]
    // T is the ultimate pointee of source and target type.
    Self.Diag(OpRange.getBegin(), diag::err_bad_const_cast_dest)
      << OrigDestType << DestRange;
    return;
  }
  SrcType = Self.Context.getCanonicalType(SrcType);

  // Unwrap the pointers. Ignore qualifiers. Terminate early if the types are
  // completely equal.
  // FIXME: const_cast should probably not be able to convert between pointers
  // to different address spaces.
  // C++ 5.2.11p3 describes the core semantics of const_cast. All cv specifiers
  // in multi-level pointers may change, but the level count must be the same,
  // as must be the final pointee type.
  while (SrcType != DestType &&
         Self.UnwrapSimilarPointerTypes(SrcType, DestType)) {
    SrcType = SrcType.getUnqualifiedType();
    DestType = DestType.getUnqualifiedType();
  }

  // Doug Gregor said to disallow this until users complain.
#if 0
  // If we end up with constant arrays of equal size, unwrap those too. A cast
  // from const int [N] to int (&)[N] is invalid by my reading of the
  // standard, but g++ accepts it even with -ansi -pedantic.
  // No more than one level, though, so don't embed this in the unwrap loop
  // above.
  const ConstantArrayType *SrcTypeArr, *DestTypeArr;
  if ((SrcTypeArr = Self.Context.getAsConstantArrayType(SrcType)) &&
     (DestTypeArr = Self.Context.getAsConstantArrayType(DestType)))
  {
    if (SrcTypeArr->getSize() != DestTypeArr->getSize()) {
      // Different array sizes.
      Self.Diag(OpRange.getBegin(), diag::err_bad_cxx_cast_generic)
        << "const_cast" << OrigDestType << OrigSrcType << OpRange;
      return;
    }
    SrcType = SrcTypeArr->getElementType().getUnqualifiedType();
    DestType = DestTypeArr->getElementType().getUnqualifiedType();
  }
#endif

  // Since we're dealing in canonical types, the remainder must be the same.
  if (SrcType != DestType) {
    // Cast between unrelated types.
    Self.Diag(OpRange.getBegin(), diag::err_bad_cxx_cast_generic)
      << "const_cast" << OrigDestType << OrigSrcType << OpRange;
    return;
  }
//.........这里部分代码省略.........