[libcxx][filesystem] Test for last_write_time

Dear all,

I'm currently experiencing some issues with
e_time.pass.cpp, with the test cases set_last_write_time_dynamic_env_test,
test_write_min_time and test_write_min_max_time to be more specific.
They try to set negative timestamps (before 1970), file_time_type::min() and
file_time_type::max(). My NFS setup doesn't like that and therefore fails
these tests. XFS works but I think ext4 also has limitations on its
timestamps. I wonder if it's a good idea to have tests that rely on
filesystem behavior that is not guaranteed...


Thanks for the info Jonas, I’ll clean up those tests.


Great. Could you possibly also have a look at this patch, that fixes a problem with setgid? https://reviews.llvm.org/D22265



Please send patches to cfe-commits.

@Jonas Could you please confirm this patch works?