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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: int status; wait (&status); WIFEXITED(status); 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: > > http://pubs.opengroup.org/onlinepubs/9699919799/basedefs/sys_wait.h.html#tag_13_71 > > "The <sys/wait.h> header shall define the following macros for analysis of > process status values: > > WEXITSTATUS > Return exit status. > WIFCONTINUED > [XSI] [Option Start] True if child has been continued. [Option End] > WIFEXITED > True if child exited normally. > ..." > > and: > > http://pubs.opengroup.org/onlinepubs/9699919799/functions/waitpid.html > > "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 > stat_loc. > > WIFEXITED(stat_val) > Evaluates to a non-zero value if status was returned for a child process > that terminated normally. > WEXITSTATUS(stat_val)" > > > 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 desired: 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 -- Corinna Vinschen Please, send mails regarding Cygwin to Cygwin Maintainer cygwin AT cygwin DOT com Red Hat
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