c/6515: incorrect bitfield promotion

[ms@siroyan.com]

>Number:         6515
>Category:       c
>Synopsis:       incorrect bitfield promotion
>Confidential:   no
>Severity:       serious
>Priority:       medium
>Responsible:    unassigned
>State:          open
>Class:          sw-bug
>Submitter-Id:   net
>Arrival-Date:   Tue Apr 30 02:16:01 PDT 2002
>Closed-Date:
>Last-Modified:
>Originator:     ms@siroyan.com
>Release:        3.0.4
>Organization:
>Environment:
i686-pc-linux-gnu
>Description:
In the attached example test1() and test2() both
perform a % operation. I expected an unsigned mod
operation performed in both cases, in practice it only
occurs in the second case, in the former case the
(unsigned int)cast appears to have no effect.

I expected:
* x.b cast to (unsigned int)
* x.a promoted to int by integral promotion
* x.a converted to (unsigned int), by arithmetic conversion
to bring x.a x.b to a common type.
* unsigned mod applied to x.a and x.b
>How-To-Repeat:
gcc -O2 x.c
./a.out
>Fix:

>Release-Note:
>Audit-Trail:
>Unformatted:
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