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More cleanup of the type traits implementation. 

1) Moved the completeness checking routine above the evaluation routine
   so the reader sees that we do in fact check for complete types when
   necessary.
2) Remove the FIXME comment about not doing this.
3) Make the arguments to the evaluate function agree in order with those
   to the completeness checking function.
4) Completely specify the enumerators for the completeness checking
   function rather than relying on a default.
5) Remove a check for the Borland language to only require complete
   types in a few places. Borland's own documentation doesn't agree with
   this: some of the previously unspecified traits *do* require
   a complete type, some don't.
6) Correctly split the traits which do not require complete types from
   those that do, clarifying comments and citations to the standard or
   other documentation where relevant.

llvm-svn: 130641
This commit is contained in:
Chandler Carruth 2011-05-01 06:51:22 +00:00
parent ddc91b25e3
commit 8e172c6054
1 changed files with 110 additions and 81 deletions
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191
clang/lib/Sema/SemaExprCXX.cpp
View File

@ -2351,15 +2351,117 @@ ExprResult Sema::ActOnUnaryTypeTrait(UnaryTypeTrait UTT,
return BuildUnaryTypeTrait(UTT, KWLoc, TSInfo, RParen);
}
static bool EvaluateUnaryTypeTrait(Sema &Self, UnaryTypeTrait UTT, QualType T,
SourceLocation KeyLoc) {
// FIXME: For many of these traits, we need a complete type before we can
// check these properties.
/// \brief Check the completeness of a type in a unary type trait.
///
/// If the particular type trait requires a complete type, tries to complete
/// it. If completing the type fails, a diagnostic is emitted and false
/// returned. If completing the type succeeds or no completion was required,
/// returns true.
static bool CheckUnaryTypeTraitTypeCompleteness(Sema &S,
UnaryTypeTrait UTT,
SourceLocation Loc,
QualType ArgTy) {
// C++0x [meta.unary.prop]p3:
// For all of the class templates X declared in this Clause, instantiating
// that template with a template argument that is a class template
// specialization may result in the implicit instantiation of the template
// argument if and only if the semantics of X require that the argument
// must be a complete type.
// We apply this rule to all the type trait expressions used to implement
// these class templates. We also try to follow any GCC documented behavior
// in these expressions to ensure portability of standard libraries.
switch (UTT) {
// FIXME: These shouldn't be UnaryTypeTraits as they aren't traits on types.
case UTT_IsLvalueExpr:
case UTT_IsRvalueExpr:
assert(0 && "Expression traits found in type trait handling code.");
if (T->isDependentType()) {
Self.Diag(KeyLoc, diag::err_dependent_type_used_in_type_trait_expr) << T;
return false;
// is_complete_type somewhat obviously cannot require a complete type.
case UTT_IsCompleteType:
// Fallthrough
// These traits are modeled on the type predicates in C++0x
// [meta.unary.cat] and [meta.unary.comp]. They are not specified as
// requiring a complete type, as whether or not they return true cannot be
// impacted by the completeness of the type.
case UTT_IsVoid:
case UTT_IsIntegral:
case UTT_IsFloatingPoint:
case UTT_IsArray:
case UTT_IsPointer:
case UTT_IsLvalueReference:
case UTT_IsRvalueReference:
case UTT_IsMemberFunctionPointer:
case UTT_IsMemberObjectPointer:
case UTT_IsEnum:
case UTT_IsUnion:
case UTT_IsClass:
case UTT_IsFunction:
case UTT_IsReference:
case UTT_IsArithmetic:
case UTT_IsFundamental:
case UTT_IsObject:
case UTT_IsScalar:
case UTT_IsCompound:
case UTT_IsMemberPointer:
// Fallthrough
// These traits are modeled on type predicates in C++0x [meta.unary.prop]
// which requires some of its traits to have the complete type. However,
// the completeness of the type cannot impact these traits' semantics, and
// so they don't require it. This matches the comments on these traits in
// Table 49.
case UTT_IsConst:
case UTT_IsVolatile:
case UTT_IsSigned:
case UTT_IsUnsigned:
return true;
// C++0x [meta.unary.prop] Table 49 requires the following traits to be
// applied to a complete type, so we enumerate theme here even though the
// default for non-Borland compilers is to require completeness for any
// other traits than the ones specifically allowed to work on incomplete
// types.
case UTT_IsTrivial:
case UTT_IsStandardLayout:
case UTT_IsPOD:
case UTT_IsLiteral:
case UTT_IsEmpty:
case UTT_IsPolymorphic:
case UTT_IsAbstract:
// Fallthrough
// These trait expressions are designed to help implement predicats in
// [meta.unary.prop] despite not being named the same. They are specified
// by both GCC and the Embarcadero C++ compiler, and require the complete
// type due to the overarching C++0x type predicates being implemented
// requiring the complete type.
case UTT_HasNothrowAssign:
case UTT_HasNothrowConstructor:
case UTT_HasNothrowCopy:
case UTT_HasTrivialAssign:
case UTT_HasTrivialConstructor:
case UTT_HasTrivialCopy:
case UTT_HasTrivialDestructor:
case UTT_HasVirtualDestructor:
// Arrays of unknown bound are expressly allowed.
QualType ElTy = ArgTy;
if (ArgTy->isIncompleteArrayType())
ElTy = S.Context.getAsArrayType(ArgTy)->getElementType();
// The void type is expressly allowed.
if (ElTy->isVoidType())
return true;
return !S.RequireCompleteType(
Loc, ElTy, diag::err_incomplete_type_used_in_type_trait_expr);
}
}
static bool EvaluateUnaryTypeTrait(Sema &Self, UnaryTypeTrait UTT,
SourceLocation KeyLoc, QualType T) {
assert(!T->isDependentType() &&
"Cannot evaluate type trait on dependent type");
ASTContext &C = Self.Context;
switch(UTT) {
@ -2653,79 +2755,6 @@ static bool EvaluateUnaryTypeTrait(Sema &Self, UnaryTypeTrait UTT, QualType T,
}
}
/// \brief Check the completeness of a type in a unary type trait.
///
/// If the particular type trait requires a complete type, tries to complete
/// it. If completing the type fails, a diagnostic is emitted and false
/// returned. If completing the type succeeds or no completion was required,
/// returns true.
static bool CheckUnaryTypeTraitTypeCompleteness(Sema &S,
UnaryTypeTrait UTT,
SourceLocation Loc,
QualType ArgTy) {
// C++0x [meta.unary.prop]p3:
// For all of the class templates X declared in this Clause, instantiating
// that template with a template argument that is a class template
// specialization may result in the implicit instantiation of the template
// argument if and only if the semantics of X require that the argument
// must be a complete type.
// We apply this rule to all the type trait expressions used to implement
// these class templates. We also try to follow any GCC documented behavior
// in these expressions to ensure portability of standard libraries.
switch (UTT) {
// is_complete_type somewhat obviously cannot require a complete type.
case UTT_IsCompleteType:
return true;
// According to http://gcc.gnu.org/onlinedocs/gcc/Type-Traits.html
// all traits except __is_class, __is_enum and __is_union require a the type
// to be complete, an array of unknown bound, or void.
case UTT_IsClass:
case UTT_IsEnum:
case UTT_IsUnion:
return true;
default:
// Apprantely Borland only wants the explicitly listed traits to complete
// the type.
if (S.LangOpts.Borland) return true;
// C++0x [meta.unary.prop] Table 49 requires the following traits to be
// applied to a complete type, so we enumerate theme here even though the
// default for non-Borland compilers is to require completeness for any
// other traits than the ones specifically allowed to work on incomplete
// types.
// FIXME: C++0x: This list is incomplete, and the names don't always
// correspond clearly to entries in the standard's table.
case UTT_HasNothrowAssign:
case UTT_HasNothrowConstructor:
case UTT_HasNothrowCopy:
case UTT_HasTrivialAssign:
case UTT_HasTrivialConstructor:
case UTT_HasTrivialCopy:
case UTT_HasTrivialDestructor:
case UTT_HasVirtualDestructor:
case UTT_IsAbstract:
case UTT_IsEmpty:
case UTT_IsLiteral:
case UTT_IsPOD:
case UTT_IsPolymorphic:
case UTT_IsStandardLayout:
case UTT_IsTrivial:
// Arrays of unknown bound are expressly allowed.
QualType ElTy = ArgTy;
if (ArgTy->isIncompleteArrayType())
ElTy = S.Context.getAsArrayType(ArgTy)->getElementType();
// The void type is expressly allowed.
if (ElTy->isVoidType())
return true;
return !S.RequireCompleteType(
Loc, ElTy, diag::err_incomplete_type_used_in_type_trait_expr);
}
}
ExprResult Sema::BuildUnaryTypeTrait(UnaryTypeTrait UTT,
SourceLocation KWLoc,
@ -2737,7 +2766,7 @@ ExprResult Sema::BuildUnaryTypeTrait(UnaryTypeTrait UTT,
bool Value = false;
if (!T->isDependentType())
Value = EvaluateUnaryTypeTrait(*this, UTT, T, KWLoc);
Value = EvaluateUnaryTypeTrait(*this, UTT, KWLoc, T);
return Owned(new (Context) UnaryTypeTraitExpr(KWLoc, UTT, TSInfo, Value,
RParen, Context.BoolTy));