cc -O2 -pipe  -pthread  -Wall -Wextra -Werror -Wno-error=deprecated -Wno-error=deprecated-declarations langinfo/ERA_D_FMT.c -o langinfo/ERA_D_FMT -D_POSIX_C_SOURCE=202405L  -lm -lpthread 
langinfo/ERA_D_FMT.c:2:17: error: use of undeclared identifier 'ERA_D_FMT'
int const foo = ERA_D_FMT;
                ^
1 error generated.