std: Redesign c_str and c_vec

This commit is an implementation of [RFC 494][rfc] which removes the entire
`std::c_vec` module and redesigns the `std::c_str` module as `std::ffi`.

[rfc]: https://github.com/rust-lang/rfcs/blob/master/text/0494-c_str-and-c_vec-stability.md

The interface of the new `CString` is outlined in the linked RFC, the primary
changes being:

* The `ToCStr` trait is gone, meaning the `with_c_str` and `to_c_str` methods
  are now gone. These two methods are replaced with a `CString::from_slice`
  method.
* The `CString` type is now just a wrapper around `Vec<u8>` with a static
  guarantee that there is a trailing nul byte with no internal nul bytes. This
  means that `CString` now implements `Deref<Target = [c_char]>`, which is where
  it gains most of its methods from. A few helper methods are added to acquire a
  slice of `u8` instead of `c_char`, as well as including a slice with the
  trailing nul byte if necessary.
* All usage of non-owned `CString` values is now done via two functions inside
  of `std::ffi`, called `c_str_to_bytes` and `c_str_to_bytes_with_nul`. These
  functions are now the one method used to convert a `*const c_char` to a Rust
  slice of `u8`.

Many more details, including newly deprecated methods, can be found linked in
the RFC. This is a:

[breaking-change]
Closes #20444

1 files changed, 2 insertions, 2 deletions

diff --git a/src/libstd/sys/unix/pipe.rs b/src/libstd/sys/unix/pipe.rs
index 9063fbc2ba9..158a1ce2204 100644
--- a/src/libstd/sys/unix/pipe.rs
+++ b/src/libstd/sys/unix/pipe.rs
@@ -10,8 +10,8 @@
 
 use prelude::v1::*;
 
+use ffi::CString;
 use libc;
-use c_str::CString;
 use mem;
 use sync::{Arc, Mutex};
 use sync::atomic::{AtomicBool, Ordering};
@@ -48,7 +48,7 @@ fn addr_to_sockaddr_un(addr: &CString,
     }
     s.sun_family = libc::AF_UNIX as libc::sa_family_t;
     for (slot, value) in s.sun_path.iter_mut().zip(addr.iter()) {
-        *slot = value;
+        *slot = *value;
     }
 
     // count the null terminator