Re: question regarding new warning

[mveksler at tx dot technion dot ac dot il]

Quoting Andrew Haley <aph@redhat.com>:

> On 03/27/2014 08:52 AM, Florian Weimer wrote:
> > On 03/27/2014 08:44 AM, Andrew Haley wrote:
> >
> > > On 03/26/2014 03:05 PM, Daniel Gutson wrote:
> > >
> > > >      assigning a negative literal to an unsigned variable issues  
> > > > no warning:
> > > >
> > > >
> > > >     unsigned int x;
> > > >     x =- 4;
> > > >
> > > > This is specially important in typos when -= was intended instead of =-
> > > >
> > > > Would be acceptable if I add a new warning to handle this, i.e.
> > > >    -Wnegative-to-unsigned
> > > > or alike?
> > >
> > > Assigning a negative literal to an unsigned variable is well-defined
> > > standard C.  Is it really appropriate to warn for correct code?
> >
> > Yes, this warning needs to take whitespace into account.  But then, I
> > suppose it would be fine.
>
> I agree.

What about when x is signed, and what about
  x =+ 4;

They are equally valid but, again, look fishy.
Why limit the warning to 'x =- 4' when x is unsigned?
This reminds me of the following C scenario:
   while (t= strchr(t, ' ')) ....
Which generates a warning despite being perfectly valid.

Michael