https://gcc.gnu.org/bugzilla/show_bug.cgi?id=85866
--- Comment #1 from Guillaume Racicot <gufideg at gmail dot com> ---
I tried some similar cases, and It seems it only happens when the expression
`(std::declval<U>().*std::declval<V>())()` is inside template parameters. In
the return type and normal function parameter it works as usual:
#include <utility>
template<typename...>
using void_t = void;
template<typename U, typename V>
void_t<decltype(
(std::declval<U>().*std::declval<V>())()
)> boom(){}
struct Foo {
void bar(){}
};
int main() {
boom<Foo, decltype(&Foo::bar)>();
}
Live example: https://godbolt.org/g/vTE9Sr
