https://gcc.gnu.org/bugzilla/show_bug.cgi?id=52099
--- Comment #4 from Jonathan Wakely <redi at gcc dot gnu.org> ---
Further discussion from PR 67772:
Consider:
namespace std { struct type_info {}; }
struct A {};
auto x = typeid(void(A::*)() const);
Clang emits the type info as:
_ZTIM1AKFvvE:
.quad _ZTVN10__cxxabiv129__pointer_to_member_type_infoE+16
.quad _ZTSM1AKFvvE
.long 0 # 0x0
.zero 4
.quad _ZTIKFvvE
.quad _ZTI1A
GCC emits it as:
_ZTIM1AKFvvE:
.quad _ZTVN10__cxxabiv129__pointer_to_member_type_infoE+16
.quad _ZTSM1AKFvvE
.long 0
.zero 4
.quad _ZTIFvvE
.quad _ZTI1A
It appears that Clang is correct here; the 'const' in this case is not a
qualifier, so should not be removed when forming the pointee type_info. If GCC
really did think this was a const qualifier applied to a function type, it
would be emitting the wrong flags (should be .long 1, not .long 0 in that
case).
This translates into a wrong-code bug in a case like this:
struct A;
extern "C" void puts(const char*);
int main() {
try {
throw (void(A::*)())0;
} catch (void (A::*)() const) {
puts("bad catch");
}
}
... where GCC erroneously catches a pointer to non-const member function as a
pointer to const member function.
