[PATCH] Fix -Wshadow=local warnings in genautomata.c

[Eric Gallager]

On 10/16/19, Jakub Jelinek <jakub@redhat.com> wrote:
> On Wed, Oct 16, 2019 at 10:03:51AM -0600, Martin Sebor wrote:
>> > The counter example would be:
>> > #define F(x) \
>> >    __extension__ (({ __typeof__ (x) _x = x; _x < 0 ? -_x : _x; }))
>> > #define G(x) \
>> >    __extension__ (({ __typeof__ (x) _x = x; F(_x); }))
>> > where a -Wshadow diagnostics could point the author at a serious bug,
>> > because in the expansion it will be __typeof__ (_x) _x = _x; ...
>>
>> True.  I don't suppose there is a way to make it so the warning
>> triggers for the counter example and not for the original, is
>> there?
>
> Maybe look through the macro nesting context and if the shadowing
> declaration comes from the same macro as shadowed declaration
> or macro included directly or indirectly from the macro with shadowed
> declaration, warn, otherwise not?
> This might still not warn in case where the scope of the shadowing
> declaration is created from multiple macros ({ coming from one,
> }) from another one, but otherwise could work.
> Perhaps -Wshadow-local needs multiple modes, the default one that
> will have this macro handling and full one (=2) which would warn
> regardless of macro definitions.
>

I'm worried about the proliferation of the number of '=' signs here...
there's already confusion as to whether the first '=' represents
levels or just a different spelling of names, adding a second would
only compound the confusion.

> 	Jakub
>