[cfe-dev] libc++: tests of the form wait*.exception.pass.cpp

[Andrew Parker]

Thanks Eric.  A deeper comment would be welcomed.

I don't use LIT to run the tests unfortunately.  My needs are bespoke so I
have a custom framework for running them.  Since this issue is particular
to me I won't push on the #define issue.  No point polluting the code for
one person.

On Sat, Aug 8, 2015 at 12:15 AM, Eric Fiselier <eric at efcs.ca> wrote:

> Hi Andrew,
>
> Please see this patch http://reviews.llvm.org/D11046. That patch adds
> a more verbose comment that at least explains the point of the test.
> It doesn't describe how the expected behavior is achieved. I'll add
> that before submitting.
>
> I prefer not to use '#if _LIBCPP_STD_VER` to wrap C++11/C++14 only
> tests. Instead I prefer to use LIT's 'REQUIRES', 'UNSUPPORTED' and
> 'XFAIL' features. This might be inconvenient if you don't use LIT to
> run the test suite.
>
> Libc++ also tends to back-port support for things like `wait_for` to
> older standard dialects. I wouldn't want libc++ to lose test coverage
> of these back-ported extensions. Hopefully we can work towards a
> solution that allows non-standard tests to be disabled without libc++
> losing coverage.
>
> /Eric
>
>
>
>
>
> On Fri, Aug 7, 2015 at 5:13 AM, Andrew Parker
> <andrew.j.c.parker at gmail.com> wrote:
> > I've just spent a lot of time trying to figure out why a particular
> class of
> > tests were failing for me with MSVC and not with GCC.
> >
> > For example:
> >
> >
> test\std\thread\thread.condition\thread.condition.condvarany\wait_for.exception.pass.cpp
> >
> > These tests are designed to check that std::condition_variable::wait_for
> > (and friends) will call std::terminate when an exception is thrown during
> > the re-locking of the passed in mutex.
> >
> > Firstly, I think this is C++14 only, at least according to
> > http://en.cppreference.com/w/cpp/thread/condition_variable/wait_for.  I
> know
> > that's not the single source of truth so please correct me if that's not
> the
> > case.  If it is, then I'd like to comment out these tests in a:
> >
> > #if _LIBCPP_STD_VER > 11
> > #else
> > #endif
> >
> > block.
> >
> > Secondly, I'd like to add a much more verbose comment as to what these
> tests
> > are doing and why, ultimately, they will work.  The latter point is the
> more
> > important.  To implement the expected behaviour the tests rely on the
> dtr of
> > std::unique_ptr calling a nothrow function and the mutex locking
> happening
> > from within there (this is why MSVC failed the test as it doesn't call
> > std::terminate if a throw occurs in a nothrow function).
> >
> > I'll submit a patch (or not) based on comments.
> >
> > Also, on a side not whilst I remember.  The following functions in
> > condition_variable.cpp are marked as NOTHROW but actually can throw:
> >
> > void
> > condition_variable::wait(unique_lock<mutex>& lk)
> >
> > void
> > condition_variable::__do_timed_wait(unique_lock<mutex>& lk,
> >      chrono::time_point<chrono::system_clock, chrono::nanoseconds> tp)
> >
> > Seems like a bug to me!  Is it?
> >
> > _______________________________________________
> > cfe-dev mailing list
> > cfe-dev at lists.llvm.org
> > http://lists.llvm.org/cgi-bin/mailman/listinfo/cfe-dev
> >
>
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