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.
Jakub
