┌─(luka@localhost:pts/5──(~)
└─>>> cat dumb.c 
#include <stdio.h>

int main()
{
    if (1 < 5);
        printf("Less\n");
    return 0;
}
┌─(luka@localhost:pts/5──(~)
└─>>> gcc -Wall -Werror dumb.c -o dumb             
┌─(luka@localhost:pts/5──(~)
└─>>> clang -Wall -Werror dumb.c -o dumb   
dumb.c:5:15: error: if statement has empty body [-Wempty-body]
    if (1 < 5);
              ^
1 error generated.
┌─(luka@localhost:pts/5──(~)
└─>>>