Warning about -Wmain for local variables

[Prathamesh Kulkarni]

On 28 June 2018 at 08:46, Jeff Law <law@redhat.com> wrote:
> On 05/30/2018 09:51 AM, Prathamesh Kulkarni wrote:
>> On 30 May 2018 at 18:12, Jonathan Wakely <jwakely.gcc@gmail.com> wrote:
>>> On 30 May 2018 at 11:40, Prathamesh Kulkarni wrote:
>>>> gcc with -Wmain warns for local variables named main.
>>>>
>>>> int foo()
>>>> {
>>>>   int main = 0;
>>>>   return main;
>>>> }
>>>>
>>>> a.c: In function ‘foo’:
>>>> a.c:3:7: warning: ‘main’ is usually a function [-Wmain]
>>>>    int main = 1;
>>>>        ^~~~
>>>>
>>>> Is this intended ? I assumed that the warning's intent was for
>>>> diagnosing variable named main having only external linkage.
>>> It was added more than 20 years ago by https://gcc.gnu.org/r13517 and
>>> looks like it has always worked as it does now, without considering
>>> linkage.
>>>
>>> Only warning for entities with external linkage seems reasonable to
>>> me, but that would be for the C front-end or diagnostics maintainers
>>> to decide.
>> Thanks for the suggestions. I have attached (untested) patch that warns
>> for Wmain if TREE_PUBLIC (decl) is true.
>> Does it look OK ?
>>
>> Thanks,
>> Prathamesh
>>
>>
>> wmain-1.txt
>>
>>
>> 2018-05-30  Prathamesh Kulkarni  <prathamesh.kulkarni@linaro.org>
>>
>>       * c/c-decl.c (start_decl): Add check TREE_PUBLIC (decl) for -Wmain.
>>
>> testsuite/
>>       * gcc.dg/wmain.c: New.
> After the usual testing, this is OK.
Sorry for late response. I committed the patch after bootstrap+test on x86_64.

Regards,
Prathamesh
>
> jeff