[Bug c/114746] With FLT_EVAL_METHOD = 2, -fexcess-precision=fast reduces the precision of floating-point constants and floating-point constant expressions

[vincent-gcc at vinc17 dot net via Gcc-bugs]

https://gcc.gnu.org/bugzilla/show_bug.cgi?id=114746

--- Comment #7 from Vincent Lefèvre <vincent-gcc at vinc17 dot net> ---
BTW, in /usr/include/math.h from the GNU libc 2.37:

# define M_PI           3.14159265358979323846  /* pi */

i.e. M_PI is defined with 21 digits in base 10, which corresponds to about 70
digits in base 2, thus with the apparent intent to be accurate in extended
precision (64 digits).