https://gcc.gnu.org/bugzilla/show_bug.cgi?id=69371
--- Comment #3 from Jonathan Wakely <redi at gcc dot gnu.org> ---
(In reply to Ed Smith-Rowland from comment #2)
> The message looks more like a header - cmath - is not included or that
> the line
> // { dg-options "-D__STDCPP_WANT_MATH_SPEC_FUNCS__" }
> or equivalent is not set.
>
> But my fresh checkout has the necessary things..
Yes, I wondered if including <limits> first was somehow preventing the extra
bits of <cmath> being included but it looks OK to me.
Preprocessed source will tell us what's happening.