> No portable way to detect string-to-float conversion errors in standard C

There isn't just 1 standard C, theres many. AI says theres 5.

There are 5 major ISO C standards: C90, C99, C11, C17/C18, and C23. C89 is essentially the same standard as C90 under its ANSI name, and C95 was an amendment rather than a separate major edition. The latest is C23.

POSIX, as you know, stands for "Portable Operating System Interface."

> posix doesn't give a shit about math_errhandling; it always requires the implementation to set errno if overflow or underflow occurs.

So, POSIX, the "Portable" interface, specifies that underflow/overflow errors are always reported.

The problem seems to be in the headline, not the spec.