Re: error: logical && with non-zero constant will always evaluate as true

[Guy Harris <guy () alum mit edu>]

On Jan 3, 2013, at 1:40 PM, Jeff Morriss <jeff.morriss.ws () gmail com> wrote:

> Jeff Morriss wrote:
> > My (Fedora 10) gcc 4.3.2 was also generating this warning; it would seem that a fair spread of gcc versions seem to 
> > have the problem.
> > I added a configure check to stop using -Wlogical-op if the compiler is generating this warning in r46916.
>
> Interestingly the Ubuntu buildbot says it would also get the warning:
>
> > checking whether we can add -Wlogical-op to CFLAGS... yes
> > checking whether -Wlogical-op generates warnings from strchr()... yes

Which means that

        #include <string.h>
          
        int
        foo(char *sep, int c)
        {
                if (strchr (sep, c) != NULL)
                        return 1;
                else
                        return 0;
        }

        int
        main(int argc, char **argv)
        {
                return foo(\"<\", 'a');
        }

fails to compile with the CFLAGS value at the time the test is done, plus -Werror; it could be failing for some other 
reason.  To quote the comment when I finally got it working for -Wshadow:

        Declare foo() before defining it - if we configure with
        --enable-extra-gcc-checks, given that we're building with -Werror (so
        that we find out whether the compiler issues a warning for a particular
        construct), we have to avoid constructs that will provoke *other*
        warnings.

so the code in question has to avoid whatever other warnings are being used, and the Ubuntu buildbot builds with 
--enable-extra-gcc-checks, so it warns about functions not declared with prototypes before they're defined.  I've 
checked in a change to declare foo() before it's defined; we'll see whether that fixes it.
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