std: Stabilize APIs for the 1.6 release

This commit is the standard API stabilization commit for the 1.6 release cycle.
The list of issues and APIs below have all been through their cycle-long FCP and
the libs team decisions are listed below

Stabilized APIs

* `Read::read_exact`
* `ErrorKind::UnexpectedEof` (renamed from `UnexpectedEOF`)
* libcore -- this was a bit of a nuanced stabilization, the crate itself is now
  marked as `#[stable]` and the methods appearing via traits for primitives like
  `char` and `str` are now also marked as stable. Note that the extension traits
  themeselves are marked as unstable as they're imported via the prelude. The
  `try!` macro was also moved from the standard library into libcore to have the
  same interface. Otherwise the functions all have copied stability from the
  standard library now.
* The `#![no_std]` attribute
* `fs::DirBuilder`
* `fs::DirBuilder::new`
* `fs::DirBuilder::recursive`
* `fs::DirBuilder::create`
* `os::unix::fs::DirBuilderExt`
* `os::unix::fs::DirBuilderExt::mode`
* `vec::Drain`
* `vec::Vec::drain`
* `string::Drain`
* `string::String::drain`
* `vec_deque::Drain`
* `vec_deque::VecDeque::drain`
* `collections::hash_map::Drain`
* `collections::hash_map::HashMap::drain`
* `collections::hash_set::Drain`
* `collections::hash_set::HashSet::drain`
* `collections::binary_heap::Drain`
* `collections::binary_heap::BinaryHeap::drain`
* `Vec::extend_from_slice` (renamed from `push_all`)
* `Mutex::get_mut`
* `Mutex::into_inner`
* `RwLock::get_mut`
* `RwLock::into_inner`
* `Iterator::min_by_key` (renamed from `min_by`)
* `Iterator::max_by_key` (renamed from `max_by`)

Deprecated APIs

* `ErrorKind::UnexpectedEOF` (renamed to `UnexpectedEof`)
* `OsString::from_bytes`
* `OsStr::to_cstring`
* `OsStr::to_bytes`
* `fs::walk_dir` and `fs::WalkDir`
* `path::Components::peek`
* `slice::bytes::MutableByteVector`
* `slice::bytes::copy_memory`
* `Vec::push_all` (renamed to `extend_from_slice`)
* `Duration::span`
* `IpAddr`
* `SocketAddr::ip`
* `Read::tee`
* `io::Tee`
* `Write::broadcast`
* `io::Broadcast`
* `Iterator::min_by` (renamed to `min_by_key`)
* `Iterator::max_by` (renamed to `max_by_key`)
* `net::lookup_addr`

New APIs (still unstable)

* `<[T]>::sort_by_key` (added to mirror `min_by_key`)

Closes #27585
Closes #27704
Closes #27707
Closes #27710
Closes #27711
Closes #27727
Closes #27740
Closes #27744
Closes #27799
Closes #27801
cc #27801 (doesn't close as `Chars` is still unstable)
Closes #28968

1 files changed, 9 insertions, 14 deletions

diff --git a/src/libcore/fmt/mod.rs b/src/libcore/fmt/mod.rs
index dfd79895747..04676c0c9c8 100644
--- a/src/libcore/fmt/mod.rs
+++ b/src/libcore/fmt/mod.rs
@@ -878,7 +878,7 @@ impl<'a> Formatter<'a> {
 
         let mut prefixed = false;
         if self.alternate() {
-            prefixed = true; width += prefix.char_len();
+            prefixed = true; width += prefix.chars().count();
         }
 
         // Writes the sign if it exists, and then the prefix if it was requested
@@ -942,18 +942,13 @@ impl<'a> Formatter<'a> {
         }
         // The `precision` field can be interpreted as a `max-width` for the
         // string being formatted
-        match self.precision {
-            Some(max) => {
-                // If there's a maximum width and our string is longer than
-                // that, then we must always have truncation. This is the only
-                // case where the maximum length will matter.
-                let char_len = s.char_len();
-                if char_len >= max {
-                    let nchars = ::cmp::min(max, char_len);
-                    return self.buf.write_str(s.slice_chars(0, nchars));
-                }
+        if let Some(max) = self.precision {
+            // If there's a maximum width and our string is longer than
+            // that, then we must always have truncation. This is the only
+            // case where the maximum length will matter.
+            if let Some((i, _)) = s.char_indices().skip(max).next() {
+                return self.buf.write_str(&s[..i])
             }
-            None => {}
         }
         // The `width` field is more of a `min-width` parameter at this point.
         match self.width {
@@ -962,13 +957,13 @@ impl<'a> Formatter<'a> {
             None => self.buf.write_str(s),
             // If we're under the maximum width, check if we're over the minimum
             // width, if so it's as easy as just emitting the string.
-            Some(width) if s.char_len() >= width => {
+            Some(width) if s.chars().count() >= width => {
                 self.buf.write_str(s)
             }
             // If we're under both the maximum and the minimum width, then fill
             // up the minimum width with the specified string + some alignment.
             Some(width) => {
-                self.with_padding(width - s.char_len(), Alignment::Left, |me| {
+                self.with_padding(width - s.chars().count(), Alignment::Left, |me| {
                     me.buf.write_str(s)
                 })
             }