Re: [PATCH] Fix bogus -Wstringop-overflow warning in Ada

[Eric Botcazou <botcazou@adacore.com>]

> Meh.  OK, eventually would need "indirection" through a wide-int then.
> Like
> 
>   offset_int::from (wi::to_wide (lowbnd), TYPE_SIGN (TREE_TYPE (lowbnd)))

That would be OK if get_offset_range did the same, but it does not since it 
forces a sign-extension whatever the sign of a large type:

  signop sgn = SIGNED;
  /* Only convert signed integers or unsigned sizetype to a signed
     offset and avoid converting large positive values in narrower
     types to negative offsets.  */
  if (TYPE_UNSIGNED (type)
      && wr[0].get_precision () < TYPE_PRECISION (sizetype))
    sgn = UNSIGNED;

> I think it should extend according to sing of lowbnd?  Or does Ada
> use an unsigned lowbnd to represent a signed value here?  At least
> that's what I had issues with with your patch.

It uses sizetype like everyone else and the signedness was forced on it 
because of the POINTER_PLUS_EXPR thing, i.e. it was signed before.

-- 
Eric Botcazou