[Bug] __wait_status_to_int() is expected to be a macro
Tue Jun 12 10:01:00 GMT 2018
On Jun 8 12:43, Eric Blake wrote:
> On 06/08/2018 12:26 PM, Hans-Bernhard Bröker wrote:
> > Am 08.06.2018 um 17:16 schrieb Denis Nikiforov:
> > > /usr/include/boost/process/detail/posix/is_running.hpp:18:1: error:
> > > non-constant condition for static assertion
> > > static_assert(!WIFEXITED(still_active), "Internal Error");
> > > ^~~~~~~~~~~~~
> > >
> > > __wait_status_to_int must be a macros but it's redefined as a function.
I don't know the surrounding code, but in how for does this make
sense at all? This expression is never static, afaics:
The sense of the above expression with a constant "still_active" is
somehow beyond me.
And this has nothing to do with macro vs. inline function, nor ...
> > It must? Says who, based on what standard document?
> > For starters, nobody gets to make any such claims about
> > __wait_status_to_int(), because that's an internal implementation detail
> > of Cygwin. If at all, such a claim might be made about WIFEXITED(),
> > which is a POSIX standard element. But POSIX makes no such requirement,
> > as far as I could see on short examination.
> POSIX requires:
> "The <sys/wait.h> header shall define the following macros for analysis of
> process status values:
> Return exit status.
> [XSI] [Option Start] True if child has been continued. [Option End]
> True if child exited normally.
> "Regardless of its value, this information may be interpreted using the
> following macros, which are defined in <sys/wait.h> and evaluate to integral
> expressions; the stat_val argument is the integer value pointed to by
> Evaluates to a non-zero value if status was returned for a child process
> that terminated normally.
> Nothing in that wording requires WIFEXITED(foo) to be a compile-time
> constant if foo is also a compile-time constant, so on that grounds, Boost
> is buggy for trying to assume that WIFEXITED(constant) can be used in a
> static_assert(). On the other hand, the implementation of WIFEXITED() is
> more like Linux if it DOES result in a compile-time constant when used on a
> compile-time constant argument; so in that regards, it would ALSO be worth
> patching Cygwin, whether or not the Boost portability bug is fixed.
...with Cygwin vs. Linux.
But, assuming I'm completely off-track above and a macro is really
Defining __wait_status_to_int as function is C++-specific. I don't think
this is really required. A quick test implies the C macro definition in
sys/wait.h is sufficent for C++ as well.
Corinna Vinschen Please, send mails regarding Cygwin to
Cygwin Maintainer cygwin AT cygwin DOT com
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