http://gcc.gnu.org/bugzilla/show_bug.cgi?id=59056
--- Comment #5 from Richard Smith <richard-gccbugzilla at metafoo dot co.uk> --- (In reply to Jonathan Wakely from comment #2) > I thought if the partial specializations were ambiguous then these function > overloads should be too. Yes, this inconsistency is very surprising. GCC, EDG, and Clang all behave the same way, and yet I can find no justification for this behavior in the standard. Morally, the function call should be ambiguous. The first 'func' takes Bar<X> for any X where check<X>() is true, and the second 'func' takes Bar<X> for any X that matches Foo<T>. Neither of those constraints implies the other, so the call should be ambiguous. In Clang's case, the problem is that we fail to enforce [temp.deduct.type](14.8.2.5)/1 when partially ordering function templates -- we don't check that deduction actually succeeded in finding types that make 'A' match the 'deduced A' -- but we do check that when partially ordering class templates, and we don't spot the problem earlier because the enable_if<...> is a non-deduced context. I expect EDG and GCC have a similar bug.
