cc -O2 -pipe  -pthread  -Wall -Wextra -Werror -Wno-error=deprecated -Wno-error=deprecated-declarations signal/struct-sigevent-sigev_value.c -o signal/struct-sigevent-sigev_value -D_POSIX_C_SOURCE=202405L  -lm -lpthread 
signal/struct-sigevent-sigev_value.c:2:17: error: declaration of 'struct sigevent' will not be visible outside of this function [-Werror,-Wvisibility]
void foo(struct sigevent* bar)
                ^
signal/struct-sigevent-sigev_value.c:4:26: error: incomplete definition of type 'struct sigevent'
        union sigval *qux = &bar->sigev_value;
                             ~~~^
signal/struct-sigevent-sigev_value.c:2:17: note: forward declaration of 'struct sigevent'
void foo(struct sigevent* bar)
                ^
2 errors generated.