[PATCH] detect incompatible aliases (PR c/81854)

[Joseph Myers]

On Thu, 17 Aug 2017, Martin Sebor wrote:

> +		  || (prototype_p (t1)
> +		      && prototype_p (t2)
> +		      && !types_compatible_p (t1, t2))))

Why the restriction to prototyped types?  I'd expect a warning for an 
alias between unprototyped functions of types int () and void (), for 
example.  Or for an alias between void () and void (char), as a function 
with a char argument is not compatible with a non-prototype function in C.  
Is this an issue with the problem being diagnosed at a point where the 
langhooks for language-specific type compatibility rules aren't available?  
If that's preventing diagnosing incompatibility involving unprototyped 
functions, then the patch is OK.

-- 
Joseph S. Myers
joseph@codesourcery.com