[Bug ipa/64181] 'noexcept' on a lambda sometimes appears to get optimised away at -O2 (or above).

["miyuki at gcc dot gnu.org" <gcc-bugzilla at gcc dot gnu dot org>]

https://gcc.gnu.org/bugzilla/show_bug.cgi?id=64181

--- Comment #3 from Mikhail Maltsev <miyuki at gcc dot gnu.org> ---
A sligtly modified testcase (no templates, no lambdas, inconsistent behavior in
single invocation).

struct Raiser
{
    virtual void raise() __attribute__((noinline))
    {
        throw 1;
    }
};

struct NoExcept
{
    Raiser *m_raiser;
    NoExcept(Raiser *raiser) : m_raiser(raiser) { }

    void call() noexcept
    {
        m_raiser->raise();
    }
};

struct Helper
{
    NoExcept *m_func;
    Helper(NoExcept *func) : m_func(func) {}
    virtual void run() __attribute__((noinline))
    {
        m_func->call();
    }
};

int main() {
    Raiser raiser;
    NoExcept noex(&raiser);
    Helper helper(&noex);

    try {
        Helper *volatile ptr_vol = &helper;
        ptr_vol->run();
    } catch (int) {
        __builtin_printf("Caught int\n");
    }

    try {
        Helper *ptr = &helper;
        ptr->run();
    } catch (int) {
    }
    return 0;
}


$ g++ -std=c++11 ./test2.cc -O3 -o ./test2
$ ./test2
Caught int
terminate called after throwing an instance of 'int'
Aborted