c/6515: incorrect bitfield promotion

c/6515: incorrect bitfield promotion

[ms]

>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:
----gnatsweb-attachment----
Content-Type: application/octet-stream; name="x.c"
Content-Transfer-Encoding: base64
Content-Disposition: attachment; filename="x.c"

c3RydWN0IHsKICBpbnQgYTo3OwogIHVuc2lnbmVkIGludCBiOjY7Cn0geDsKCnVuc2lnbmVkIGlu
dCBhYSwgYmI7Cgppbml0ICgpCnsKICBhYSA9IHguYSA9IC0xMzsKICBiYiA9IHguYiA9IDYxOwp9
CgptYWluICgpCnsKICBpbml0ICgpOwogIHRlc3QxICgpOwogIHRlc3QyICgpOwp9Cgp0ZXN0MSAo
KQp7CiAgcHJpbnRmICgiJWQgJSUgJWQgPSAlZFxuIiwgeC5hLCB4LmIsIHguYSAlICgodW5zaWdu
ZWQgaW50KSB4LmIpKTsKfQoKdGVzdDIgKCkKewogIHByaW50ZiAoIiVkICUlICVkID0gJWRcbiIs
IGFhLCBiYiwgYWEgJSBiYik7Cn0K

Re: c/6515: incorrect bitfield promotion

[neil]

Synopsis: incorrect bitfield promotion

Responsible-Changed-From-To: unassigned->neil
Responsible-Changed-By: neil
Responsible-Changed-When: Wed May 22 05:09:19 2002
Responsible-Changed-Why:
    Bitfield issues are assigned to me, though I doubt I'll
    have time to fix them until 3.3.
State-Changed-From-To: open->analyzed
State-Changed-By: neil
State-Changed-When: Wed May 22 05:09:19 2002
State-Changed-Why:
    Bitfields have several issues, fundamentally down to the
    single fact that their type is not represented properly in the
    compiler.

http://gcc.gnu.org/cgi-bin/gnatsweb.pl?cmd=view%20audit-trail&database=gcc&pr=6515