On Tue, May 18, 2021 at 07:45:14PM -0500, Segher Boessenkool wrote:
> On Wed, May 19, 2021 at 10:26:22AM +1000, Michael Ellerman wrote:
> > Guenter Roeck <linux@xxxxxxxxxxxx> writes:
> > > Ah, sorry. I wasn't aware that the following is valid C code
> > >
> > > void f1()
> > > {
> > > return f2();
> > > ^^^^^^
> > > }
> > >
> > > as long as f2() is void as well. Confusing, but we live and learn.
> >
> > It might be valid, but it's still bad IMHO.
> >
> > It's confusing to readers, and serves no useful purpose.
>
> And it actually explicitly is undefined behaviour in C90 already
> (3.6.6.4 in C90, 6.8.6.4 in C99 and later).
... but there is a GCC extension that allows this by default:
<https://gcc.gnu.org/onlinedocs/gcc/Warning-Options.html#index-Wreturn-type>
For C only, warn about a 'return' statement with an expression in a
function whose return type is 'void', unless the expression type is
also 'void'. As a GNU extension, the latter case is accepted
without a warning unless '-Wpedantic' is used.
Segher
