Rollup merge of rust-lang#30943 - alexcrichton:stabilize-1.7, r=aturon

This commit stabilizes and deprecates the FCP (final comment period) APIs for
the upcoming 1.7 beta release. The specific APIs which changed were:

Stabilized

* `Path::strip_prefix` (renamed from `relative_from`)
* `path::StripPrefixError` (new error type returned from `strip_prefix`)
* `Ipv4Addr::is_loopback`
* `Ipv4Addr::is_private`
* `Ipv4Addr::is_link_local`
* `Ipv4Addr::is_multicast`
* `Ipv4Addr::is_broadcast`
* `Ipv4Addr::is_documentation`
* `Ipv6Addr::is_unspecified`
* `Ipv6Addr::is_loopback`
* `Ipv6Addr::is_unique_local`
* `Ipv6Addr::is_multicast`
* `Vec::as_slice`
* `Vec::as_mut_slice`
* `String::as_str`
* `String::as_mut_str`
* `<[T]>::clone_from_slice` - the `usize` return value is removed
* `<[T]>::sort_by_key`
* `i32::checked_rem` (and other signed types)
* `i32::checked_neg` (and other signed types)
* `i32::checked_shl` (and other signed types)
* `i32::checked_shr` (and other signed types)
* `i32::saturating_mul` (and other signed types)
* `i32::overflowing_add` (and other signed types)
* `i32::overflowing_sub` (and other signed types)
* `i32::overflowing_mul` (and other signed types)
* `i32::overflowing_div` (and other signed types)
* `i32::overflowing_rem` (and other signed types)
* `i32::overflowing_neg` (and other signed types)
* `i32::overflowing_shl` (and other signed types)
* `i32::overflowing_shr` (and other signed types)
* `u32::checked_rem` (and other unsigned types)
* `u32::checked_shl` (and other unsigned types)
* `u32::saturating_mul` (and other unsigned types)
* `u32::overflowing_add` (and other unsigned types)
* `u32::overflowing_sub` (and other unsigned types)
* `u32::overflowing_mul` (and other unsigned types)
* `u32::overflowing_div` (and other unsigned types)
* `u32::overflowing_rem` (and other unsigned types)
* `u32::overflowing_neg` (and other unsigned types)
* `u32::overflowing_shl` (and other unsigned types)
* `u32::overflowing_shr` (and other unsigned types)
* `ffi::IntoStringError`
* `CString::into_string`
* `CString::into_bytes`
* `CString::into_bytes_with_nul`
* `From<CString> for Vec<u8>`
* `From<CString> for Vec<u8>`
* `IntoStringError::into_cstring`
* `IntoStringError::utf8_error`
* `Error for IntoStringError`

Deprecated

* `Path::relative_from` - renamed to `strip_prefix`
* `Path::prefix` - use `components().next()` instead
* `os::unix::fs` constants - moved to the `libc` crate
* `fmt::{radix, Radix, RadixFmt}` - not used enough to stabilize
* `IntoCow` - conflicts with `Into` and may come back later
* `i32::{BITS, BYTES}` (and other integers) - not pulling their weight
* `DebugTuple::formatter` - will be removed
* `sync::Semaphore` - not used enough and confused with system semaphores

Closes rust-lang#23284
cc rust-lang#27709 (still lots more methods though)
Closes rust-lang#27712
Closes rust-lang#27722
Closes rust-lang#27728
Closes rust-lang#27735
Closes rust-lang#27729
Closes rust-lang#27755
Closes rust-lang#27782
Closes rust-lang#27798

Author: Manishearth

src/liballoc/lib.rs

@@ -78,7 +78,6 @@
 #![feature(custom_attribute)]
 #![feature(fundamental)]
 #![feature(lang_items)]
-#![feature(num_bits_bytes)]
 #![feature(optin_builtin_traits)]
 #![feature(placement_in_syntax)]
 #![feature(placement_new_protocol)]

src/liballoc/raw_vec.rs

@@ -16,7 +16,6 @@ use super::oom;
 use super::boxed::Box;
 use core::ops::Drop;
 use core::cmp;
-use core;
 
 /// A low-level utility for more ergonomically allocating, reallocating, and deallocating a
 /// a buffer of memory on the heap without having to worry about all the corner cases
@@ -584,7 +583,7 @@ impl<T> Drop for RawVec<T> {
 
 #[inline]
 fn alloc_guard(alloc_size: usize) {
-    if core::usize::BITS < 64 {
+    if mem::size_of::<usize>() < 8 {
         assert!(alloc_size <= ::core::isize::MAX as usize,
                 "capacity overflow");
     }