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Allow us to compare derived-to-base conversions between a reference 

binding and a copy-construction. Fixes an overloading problem in the
Clang-on-Clang build.

llvm-svn: 97161
This commit is contained in:
Douglas Gregor 2010-02-25 19:01:05 +00:00
parent f7fc2d8b86
commit 83af86a6bc
2 changed files with 21 additions and 27 deletions
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35
clang/lib/Sema/SemaOverload.cpp
View File

@ -2094,32 +2094,6 @@ Sema::CompareDerivedToBaseConversions(const StandardConversionSequence& SCS1,
}
}
// Compare based on reference bindings.
if (SCS1.ReferenceBinding && SCS2.ReferenceBinding &&
SCS1.Second == ICK_Derived_To_Base) {
// -- binding of an expression of type C to a reference of type
// B& is better than binding an expression of type C to a
// reference of type A&,
if (Context.hasSameUnqualifiedType(FromType1, FromType2) &&
!Context.hasSameUnqualifiedType(ToType1, ToType2)) {
if (IsDerivedFrom(ToType1, ToType2))
return ImplicitConversionSequence::Better;
else if (IsDerivedFrom(ToType2, ToType1))
return ImplicitConversionSequence::Worse;
}
// -- binding of an expression of type B to a reference of type
// A& is better than binding an expression of type C to a
// reference of type A&,
if (!Context.hasSameUnqualifiedType(FromType1, FromType2) &&
Context.hasSameUnqualifiedType(ToType1, ToType2)) {
if (IsDerivedFrom(FromType2, FromType1))
return ImplicitConversionSequence::Better;
else if (IsDerivedFrom(FromType1, FromType2))
return ImplicitConversionSequence::Worse;
}
}
// Ranking of member-pointer types.
if (SCS1.Second == ICK_Pointer_Member && SCS2.Second == ICK_Pointer_Member &&
FromType1->isMemberPointerType() && FromType2->isMemberPointerType() &&
@ -2156,9 +2130,13 @@ Sema::CompareDerivedToBaseConversions(const StandardConversionSequence& SCS1,
}
}
if (SCS1.CopyConstructor && SCS2.CopyConstructor &&
if ((SCS1.ReferenceBinding || SCS1.CopyConstructor) &&
(SCS2.ReferenceBinding || SCS2.CopyConstructor) &&
SCS1.Second == ICK_Derived_To_Base) {
// -- conversion of C to B is better than conversion of C to A,
// -- binding of an expression of type C to a reference of type
// B& is better than binding an expression of type C to a
// reference of type A&,
if (Context.hasSameUnqualifiedType(FromType1, FromType2) &&
!Context.hasSameUnqualifiedType(ToType1, ToType2)) {
if (IsDerivedFrom(ToType1, ToType2))
@ -2168,6 +2146,9 @@ Sema::CompareDerivedToBaseConversions(const StandardConversionSequence& SCS1,
}
// -- conversion of B to A is better than conversion of C to A.
// -- binding of an expression of type B to a reference of type
// A& is better than binding an expression of type C to a
// reference of type A&,
if (!Context.hasSameUnqualifiedType(FromType1, FromType2) &&
Context.hasSameUnqualifiedType(ToType1, ToType2)) {
if (IsDerivedFrom(FromType2, FromType1))

13
clang/test/SemaCXX/overload-call.cpp
View File

@ -373,3 +373,16 @@ namespace test4 {
}
};
}
namespace DerivedToBase {
struct A { };
struct B : A { };
struct C : B { };
int &f0(const A&);
float &f0(B);
void g() {
float &fr = f0(C());
}
}