Re: implicit cast from unsigned long to unsigned int gives no warning with -Wall (64 bits arch)

[Vincent Torri <vtorri at univ-evry dot fr>]

On Wed, 21 Nov 2007, Tom St Denis wrote:

> Vincent Torri wrote:
> > hey,
> >
> > I have an ubuntu 64 bits on my core 2 duo. gcc version is 4.1.2
> >
> > I compile that code with -Wall:
> >
> >
> >
> > unsigned int htonl (unsigned int i)
> > {
> >   i = 0;
> >   return 0;
> > }
> >
> > int
> > main ()
> > {
> >   unsigned long i;
> >   unsigned int j;
> >
> >   i = 0;
> >   j = htonl (i);
>
> I want to know why you assume j = ... should give a warning but not i = 0. 
> (hint: what is the type of 0?).
>
> In C, casts are implicit.  That's how you can do things like
>
> int ch = 'a';

you can't loose data here, while a cast from a 64bits int to a 32 bits can 
loose data.

I was not precise enough : i was expecting a warning on the line where 
htonl is called

Vincent Torri