Re: Is this a gcc bug?

[Richard Earnshaw <rearnsha@arm.com>]

> On Thu, 11 Jan 2001, Joe Buck wrote:
> 
> > >
> > > > How about something like:
> > > >         warning: 'x' may have unexpected value because of side-effects
> > > > or
> > > >         warning: side-effects make value of 'x' undefined
> > > > or
> > > >         warning: undefined order of side-effects on 'x'
> > > > One might replace "side-effects" by "updates" or "changes to".
> > >
> > > How about, multiple side-effects on 'x' between sequence points?
> >
> > "sequence points" is standardese and doesn't mean anything to most users.
> > Even "side-effects" may be surprising -- I don't think a user thinks
> > of the increment of x in x++ as a "side effect".
> >
> > How about:
> >
> > warning: the order of the modifications to 'x' is undefined
> 
> Possibly "may be undefined".  I think the wording "may" was put there
> intentionally because the first versions of this code tended to generate
> false positives now and then.  This can probably still happen with the
> current version in some rare cases.

Well, I don't know if we catch it, but "x++ + x" is also undefined, but 
there is only one modification.  How about:

Expression containing 'x' has undefined meaning (more than one 
interpretation possible).

R.