c++ - Destructors and noexcept

Question

I am a little bit confused with destructors and noexcept. My understanding was that in C++11 any destructor, including user-defined, is implicitly noexcept(true), even if we throw from it. And one has to specify explicitly noexcept(false) if they want it to be that way for some reason.

I'm seeing quite the opposite - with GCC 4.7.2, the user-defined destructor, no matter how primitive the class and destructor are, is implicitly noexcept(false). What am I missing here? Is there some hidden gotcha with user-defined destructors?

Answer 1

This is a known bug (credits to the OP for finding the bug report), and it seems it has been fixed in GCC 4.8.0. For instance, the static assertion below will fire on GCC 4.7.2, but not on GCC 4.8.0:

struct X
{
    ~X() { };
};

int main()
{
    X x;

    // This will not fire even in GCC 4.7.2 if the destructor is
    // explicitly marked as noexcept(true)
    static_assert(noexcept(x.~X()), "Ouch!");
}