[Bug c/41793] [4.3/4.4/4.5 Regression] About Long long bit field

[pinskia at gcc dot gnu dot org]

------- Comment #9 from pinskia at gcc dot gnu dot org  2009-10-23 02:53 -------

>        unsigned long long a:2;
>        unsigned long long b:40;
>        unsigned long long c:22;

>        unsigned long long a = t.a - 8;
t.a gets promoted to in as t.a is less precision than int. Which causes a sign
extend to happen and then converted into unsigned long long which causes
another sign extend.

>        unsigned long long b = t.b - 8;
t.b has more precision than int so it does not get change and then it gets
promoted to unsigned long long.

>        unsigned long long c = t.c - 8;

t.c is the same as t.a.

If you used 8u then it would have been converted into unsigned int rather than
int and become the same.


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http://gcc.gnu.org/bugzilla/show_bug.cgi?id=41793