[Bug c++/100720] inconsistent return type deduction behavior with user defined conversion function

[pinskia at gcc dot gnu.org via Gcc-bugs]

https://gcc.gnu.org/bugzilla/show_bug.cgi?id=100720

--- Comment #1 from Andrew Pinski <pinskia at gcc dot gnu.org> ---
clang rejects the first example:
<source>:7:20: error: function 'f<int>' with deduced return type cannot be used
before it is defined
            return f(0);
                   ^
<source>:2:10: note: 'f<int>' declared here
    auto f(auto);
         ^

And rejects the second with a similar message as GCC.