Auto merge of #23229 - aturon:stab-path, r=alexcrichton

This commit stabilizes essentially all of the new `std::path` API. The
API itself is changed in a couple of ways (which brings it in closer
alignment with the RFC):

* `.` components are now normalized away, unless they appear at the
  start of a path. This in turn effects the semantics of e.g. asking for
  the file name of `foo/` or `foo/.`, both of which yield `Some("foo")`
  now. This semantics is what the original RFC specified, and is also
  desirable given early experience rolling out the new API.

* The `parent` method is now `without_file` and succeeds if, and only
  if, `file_name` is `Some(_)`. That means, in particular, that it fails
  for a path like `foo/../`. This change affects `pop` as well.

In addition, the `old_path` module is now deprecated.

[breaking-change]

r? @alexcrichton 

2 files changed, 3 insertions, 1 deletions

diff --git a/src/libstd/sys/unix/fs.rs b/src/libstd/sys/unix/fs.rs
index 3d490380bfd..f23619955e2 100644
--- a/src/libstd/sys/unix/fs.rs
+++ b/src/libstd/sys/unix/fs.rs
@@ -10,6 +10,8 @@
 
 //! Blocking posix-based file I/O
 
+#![allow(deprecated)] // this module itself is essentially deprecated
+
 use prelude::v1::*;
 
 use ffi::{CString, CStr};
diff --git a/src/libstd/sys/unix/process.rs b/src/libstd/sys/unix/process.rs
index d5469eb82ef..df0e8de3ff1 100644
--- a/src/libstd/sys/unix/process.rs
+++ b/src/libstd/sys/unix/process.rs
@@ -8,7 +8,7 @@
 // option. This file may not be copied, modified, or distributed
 // except according to those terms.
 
-#![allow(deprecated)]
+#![allow(deprecated)] // this module itself is essentially deprecated
 
 use prelude::v1::*;
 use self::Req::*;