It says
Note: `tcc` was not used, so unless you install it yourself, your backend C compiler will be `cc`, which is usually either `clang`, `gcc` or `msvc`.
Also you have "gcc" in your error:
See <file:///usr/share/doc/gcc-7/README.Bugs>
And on the website the claim is made for tcc and x64 backends.
Like I said, no way it'd take 15 seconds :)