Re: [PATCH 11/12] sched: use for_each_if in topology.h

[Mark Rutland]

On Mon, Jul 09, 2018 at 06:03:42PM +0200, Peter Zijlstra wrote:
> On Mon, Jul 09, 2018 at 05:52:04PM +0200, Daniel Vetter wrote:
> > for_each_something(foo)
> > 	if (foo->bla)
> > 		call_bla(foo);
> > 	else
> > 		call_default(foo);
> > 
> > Totally contrived, but this complains. Liberally sprinkling {} also shuts
> > up the compiler, but it's a bit confusing given that a plain for {;;} is
> > totally fine. And it's confusing since at first glance the compiler
> > complaining about nested if and ambigous else doesn't make sense since
> > clearly there's only 1 if there.
> 
> Ah, so the pattern the compiler tries to warn about is:
> 
> 	if (foo)
> 		if (bar)
> 			/* stmts1 */
> 		else
> 			/* stmts2 *
> 
> Because it might not be immediately obvious with which if the else goes.
> Which is fair enough I suppose.
> 
> OK, ACK.

Just to bikeshed, there could be macros other than for_each_*() macros
that will want to use this internally, so perhaps it would be worth the
generic version being named something like if_noelse().

We could always add that as/when required, though.

Mark.