ternary vs double exclamation

[john@jjdev.com (John de la Garza)]

On Sun, Jan 04, 2015 at 08:17:15PM -0500, Valdis.Kletnieks at vt.edu wrote:
> On Sun, 04 Jan 2015 18:43:22 -0500, John de la Garza said:
> > On Sat, Jan 03, 2015 at 11:20:29PM -0500, Valdis.Kletnieks at vt.edu wrote:
> > > On Sat, 03 Jan 2015 18:54:00 -0500, John de la Garza said:
> > >
> > > > It should not be assumed that true will always be 1 as defined in
> > > > include/linux/stddef.h, right?
> > >
> > > No, I mean use an actual 'bool' type rather than 'int'.  Consider this from
> > > kernel/softirq.c:
> >
> > yes, bool has two possible values true and false
> >
> > from include/linux/stddef.h:
> > enum {
> > 	        false   = 0,
> > 		true	= 1
> > };
> 
> Note that's an *anonynous* enum, which defines the two values, but
> it *doesn't* define an enum type that can be used to force type safety.
> 
> No, if you're converting a variable from int to bool, the *important* line is
> from include/linux/types.h:
> 
> typedef _Bool                   bool;
> 
> which ensures more type safety than the enum does.

right, I see that now

so _Bool is a defined by the compiler and typedefed to bool