> I think adding gcc-toolchain to propagated-inputs should work in
> principle, other than the fact that the gcc used for gcc-lib and
> libstdc++ need to be the same as the propagated gcc-toolchain. I did
> have a fix for this but I'm not sure if it's the best way of writing
> it.
> I'll send another patch with the fix though so at least others can
> comment on it!

Yes propagating gcc-toolchain would work but, would also cause gcc to be
available as a side effect. Maybe the patch attached, on top of yours,
would work?

Thanks,

Mathieu