cc -O2 -pipe  -pthread  -Wall -Wextra -Werror -Wno-error=deprecated -Wno-error=deprecated-declarations termios/VTDLY.c -o termios/VTDLY -D_POSIX_C_SOURCE=202405L  -lm -lpthread 
termios/VTDLY.c:8:17: error: use of undeclared identifier 'VTDLY'
int const foo = VTDLY;
                ^
1 error generated.