Re: [Libvir] [PATCH] libvirt.c: warning: dereferencing type-punned pointer will break strict-aliasing rules
On Fri, 2007-03-02 at 11:30 +0000, Richard W.M. Jones wrote:
I'm currently trying to get libvirt to compile with -Werror. One
problem which came up early is the warning in $SUBJECT. The gcc info
page (see -fstrict-aliasing) is pretty unclear about what exactly causes
this problem, so the attached patch rewrites the code quite
conservatively to avoid the problem.
Uggh, -fstrict-aliasing is the bane of all our lives. Whoever thought
it was a good idea? Wonder how much this optimisation actually gives us?
Is it enough to justify all this? Grr.
(Deep breath)
Does something like this work:
struct _virDriver {
const char *name;
};
struct _virDomainDriver {
struct _virDriver base;
int no;
unsigned long ver;
virDrvOpen open;
};
struct _virNetworkDriver {
struct _virDriver base;
virDrvOpen open;
};
static int
_virRegisterDriver(virDriver *driver, int isNetwork)
{
virDriver *drivers;
drivers = (virDriver *) isNetwork ? virNetworkDriverTab : virDriverTab;
...
}
I started re-factoring qemud like this so as to have a base object from
which domains and networks derive so that we don't have to have as much
copied and pasted code between the two, but it's a pretty big task.
Cheers,
Mark.