Test 'compile-fp-test' compilation fails on gcc 11 and clang 14

[jrmelsha]

fmt/include/fmt/format.h

Line 2341 in 7e4ad40

if (is_constant_evaluated()) return !isnan(value - value);

error: ‘(+Inf - +Inf)’ is not a constant expression

Fails with both c++20 and gnu++20.

I will look into an equivalent constant evaluated expression.

[vitaut]

I was not able to reproduce the issue in https://godbolt.org/z/f57vqYeGf. Could you provide a godbolt repro?

[jrmelsha]

https://godbolt.org/z/qeo5bjbxT

Was due to -O3

[vitaut]

Worked around in ae963e4, thanks for reporting!