Why can't GCC disambiguate multiple inherited functions (yet clang can)? [duplicate]

Answer 1

I think it has something to do with hiding the function(s) in the base classes, and the GCC's error message doesn't seem to help much, even if you use struct instead of enum : In fact, the error message is misleading, because now Ea and Eb are two different classes, with no implicit conversion from Ea to Eb, the ambiguity shouldn't arise, but GCC seems to disagree with me : http://ideone.com/cvzLW (see the modification also).

Anyway, if you bring the functions in the class scope, explicitly by writing using as:

struct Sbroken : Sa, Sb 
{
   using Sa::operator();
   using Sb::operator();
};

then it works : http://ideone.com/LBZgC

Same with other example as well:

struct Sbroken : Sa, Sb 
{
   using Sa::f;
   using Sb::f;
};

Code : http://ideone.com/3hojd