Re: [PATCH 1/8] nptl: Add C11 threads thrd_* functions

[Florian Weimer <fweimer at redhat dot com>]

On 11/15/2017 01:43 PM, Adhemerval Zanella wrote:
> On 15/11/2017 10:03, Florian Weimer wrote:
> > On 11/15/2017 12:22 PM, Adhemerval Zanella wrote:
> > > On 15/11/2017 06:09, Florian Weimer wrote:
> > > > On 09/22/2017 10:26 PM, Adhemerval Zanella wrote:
> > > > > This patch adds the thrd_* definitions from C11 threads (ISO/IEC
> > > > > 9899:2011),
> > > > > more specifically thrd_create, thrd_curent, rhd_detach, thrd_equal,
> > > > > thrd_exit, thrd_join, thrd_sleep, thrd_yield, and required types.
> > > > >
> > > > > Mostly of the definitions are composed based on POSIX conterparts,
> > > > > such as
> > > > > thrd_t (using pthread_t).
> > > >
> > > > I have skimmed the C11 discussion of these types, and C11 says that
> > > > mtx_t et al. are “identifiers”.  To me, this suggests they are
> > > > handles, just like pthread_t in the POSIX threads implementation.
> >
> > > My understanding is "identifiers" follow the definition from C11 6.2.1
> > > which does not exclude a tag/struct to represent it.
> >
> > I don't think “identifier” is used in this sense here.
> >
> > The standard says (7.2.6.1/4):
> >
> > “
> > The types are
> > \begin{quote}
> >    \verb|cnd_t|
> > \end{quote}
> > which is a complete object type that holds an identifier for a
> > condition variable;
> > ”
> >
> > The “holds an identifier” suggests to me that this use of the term
> > “identifier” does not refer to the C language construct.  The
> > definitions in ISO/IEC 2382:2015(en) do not seem to be applicable,
> > either.

> I find it quite inconsistent and improbable that the threads definition
> in C11
> standard is using a defined vocabulary in a different meaning than the rest
> of document.

But how can a complete object *type* hold a C identifier?  The language 
does not support that.  We don't have call-by-name or anything like that.

So this usage doesn't make sense to me, so I assume that something else 
is meant here.

I'm trying to get access to the WG papers on which the text is based. 
Maybe those illuminate what is meant here.

Thanks,
Florian