Extended Description

In some contexts, decltype(&(C::member)) yields a pointer to member type, but according to [expr.unary.op]/4, no pointer to member should be formed when the operand of the & operator is enclosed in parentheses.

http://eel.is/c++draft/expr.unary.op#4

The code below demonstrates this behavior. It compiles on all Clang versions I have tried between 3.2 and HEAD, even though I don't think it should.

#include <type_traits>
 
struct S {
    int x;

    static_assert(std::is_same<decltype(&(S::x)), int S::*>::value, ""); // !

    void foo() {
        static_assert(std::is_same<decltype(&(S::x)), int*>::value, ""); // OK
    }
};

static_assert(std::is_same<decltype(&(S::x)), int S::*>::value, ""); // !

int main() {
}