Bugfix to convert_to_integer

[Joseph S. Myers]

On Fri, 23 Feb 2001, Richard Kenner wrote:

> It isn't safe to use an unsigned type for a computation if only one operand
> was unsigned.   We might have had a case where an unsigned type was converted
> to a wider signed type and then had a negative number added in that type.
> Doing the computation as unsigned in the narrower type is wrong.
> Tested on alphaev56 and applied to main and GCC 3.0 branch.

Is this something for which a testcase could be constructed?  If so, could
you install one, or state which existing testcase it is?

-- 
Joseph S. Myers
jsm28@cam.ac.uk