`clang -ansi` extensions

Question

I ran into an issue recently where the following toy example compiles cleanly using clang -ansi:

int main(void)
{
    for (int i = 0; 0; );
             


        

Answer 1

If you are trying to disable extensions in -ansi mode, then you want these warnings treated as errors: use -pedantic-errors instead of -pedantic, or -Werror (or both). For more fine-grained control over errors, see the Clang manual.