C PATCH to add -Wswitch-unreachable (PR c/49859)

[Marek Polacek]

On Wed, May 25, 2016 at 03:21:00PM -0600, Martin Sebor wrote:
> I see.  Thanks for clarifying that.  No warning on a declaration
> alone makes sense in the case above but it has the unfortunate
> effect of suppressing the warning when the declaration is followed
> by a statement, such as in:
> 
>   void f (int*, int);
> 
>   void g (int i)
>   {
>     switch (i) {
>       int a [3];
>       memset (a, 0, sizeof a);
> 
>       default:
>       f (a, 3);
>     }
>   }

Ah, then I think we should probably look into GIMPLE_TRY, using
gimple_try_eval, too.

	Marek