Compiler turns off warnings unexpectedly

[Paolo Bonzini]

>>>> I have here an (attached) testcase which unexpectedly turns off
>>>> warnings. Compiling it using `gcc test.c -c -Wall` (or test.i) gives:
>>>>
>>>> test.c: In function 'pam_sm_authenticate':
>>>> test.c:6: warning: implicit declaration of function 'undef'
>>> This works on the trunk but fails on the 4.3 branch.
>>
>> gcc 4.1 also produces the expected output (implicit declaration undef2),
>> so it seems like a recent regression.
> 
> I guess filling a bug at http://gcc.gnu.org/bugzilla about this
> regression would help.

As would adding the reduced testcase to the testsuite for trunk to
ensure we don't regress again. :-)

Will do so next week if nobody beats me to it.

Paolo