[harrytuttle]

What compiler flag is that? Genuinely interested. Wall,pedantic,ansi don't trigger it. I've tried the following and I don't get a warning or error:

   $ cat test2.c
   int main(int argc, char *argv[]) {
       if (argc = 0)
           return 1;
       return 0;
   }
   $ make test
   cc -Wall -ansi -pedantic    test.c   -o test

GCC version: gcc version 4.7.2 (Debian 4.7.2-5)

[huhtenberg]

  huh@px:/tmp$ cat a.c
  int main(int argc, char *argv[]) {
         if (argc = 0)
             return 1;
         return 0;
     }
  huh@px:/tmp$ gcc -Wall a.c
  a.c: In function 'main':
  a.c:2: warning: suggest parentheses around assignment used as truth value

[harrytuttle]

Doesn't do that for me - what GCC ver and environment. Very odd! Digging in docs. Thanks for info.

[huhtenberg]

It's some old-ish Debian on x86. GCC is 4.3.2.

But this is a such commonly-recognized pitfall that I actually don't know a single modern production compiler that does not generate this warning.

(edit) Just checked 4.7.1 and it generates the warning.

[harrytuttle]

Thanks. I think this must be a config issue on this box. It makes me wonder what other warnings it is not telling me about.

[detrino]

Notice that you cat test2.c and then compile test.c.

[harrytuttle]

Well spotted! Thanks for pointing this out!

I will now go and hit myself with a LART for a bit to remember not to do that again.