[Bug libstdc++/114862] std::uppercase not applying to nan's and inf's

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

https://gcc.gnu.org/bugzilla/show_bug.cgi?id=114862

--- Comment #2 from Jonathan Wakely <redi at gcc dot gnu.org> ---
Libc++ has tests for "INF" (although only for long double, not float or
double), so it's apparently not accidental. The relevant code is:

  if (floatfield == ios_base::fixed) {
    if (uppercase)
      *__fmtp = 'F';
    else
      *__fmtp = 'f';

That's been there since the initial commit in 2010.

MSVC behaves the same as libstdc++.