cc -O2 -pipe  -pthread -I/usr/local/include  -Wall -Wextra -Werror -Wno-error=deprecated -Wno-error=deprecated-declarations math/M_SQRT1_3.c -o math/M_SQRT1_3 -D_POSIX_C_SOURCE=202405L  -lm -lpthread -L/usr/local/lib  -lintl
math/M_SQRT1_3.c:8:21: error: use of undeclared identifier 'M_SQRT1_3'
    8 | double  const foo = M_SQRT1_3;
      |                     ^
1 error generated.