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https://gcc.gnu.org/bugzilla/show_bug.cgi?id=3D92559

--- Comment #3 from Konstantin Kharlamov <Hi-Angel at yandex dot ru> ---
(In reply to Andrew Pinski from comment #2)
> I don't think this can ever be optimized.  Mainly because there are copies
> happening due to passing via value and returning by value.

Please correct me if I'm wrong, but it seems like, given the code in questi=
on:

    MyMap foo(MyMap m) {
        if (m[0] =3D=3D 0)
            return m;
        else {
            m[0] -=3D 1;
            return foo(m);
        }
    }

When tail-recursion optimization applied, it should be analogous to this co=
de:

    MyMap foo(MyMap m) {
        while(m[0] > 0) {
            m[0] -=3D 1;
            m =3D MyMap(m);
        }
        return m;
    }

Doesn't look impossible to me, unless of course I am missing something.=