std: Stabilize APIs for the 1.9 release

This commit applies all stabilizations, renamings, and deprecations that the
library team has decided on for the upcoming 1.9 release. All tracking issues
have gone through a cycle-long "final comment period" and the specific APIs
stabilized/deprecated are:

Stable

* `std::panic`
* `std::panic::catch_unwind` (renamed from `recover`)
* `std::panic::resume_unwind` (renamed from `propagate`)
* `std::panic::AssertUnwindSafe` (renamed from `AssertRecoverSafe`)
* `std::panic::UnwindSafe` (renamed from `RecoverSafe`)
* `str::is_char_boundary`
* `<*const T>::as_ref`
* `<*mut T>::as_ref`
* `<*mut T>::as_mut`
* `AsciiExt::make_ascii_uppercase`
* `AsciiExt::make_ascii_lowercase`
* `char::decode_utf16`
* `char::DecodeUtf16`
* `char::DecodeUtf16Error`
* `char::DecodeUtf16Error::unpaired_surrogate`
* `BTreeSet::take`
* `BTreeSet::replace`
* `BTreeSet::get`
* `HashSet::take`
* `HashSet::replace`
* `HashSet::get`
* `OsString::with_capacity`
* `OsString::clear`
* `OsString::capacity`
* `OsString::reserve`
* `OsString::reserve_exact`
* `OsStr::is_empty`
* `OsStr::len`
* `std::os::unix::thread`
* `RawPthread`
* `JoinHandleExt`
* `JoinHandleExt::as_pthread_t`
* `JoinHandleExt::into_pthread_t`
* `HashSet::hasher`
* `HashMap::hasher`
* `CommandExt::exec`
* `File::try_clone`
* `SocketAddr::set_ip`
* `SocketAddr::set_port`
* `SocketAddrV4::set_ip`
* `SocketAddrV4::set_port`
* `SocketAddrV6::set_ip`
* `SocketAddrV6::set_port`
* `SocketAddrV6::set_flowinfo`
* `SocketAddrV6::set_scope_id`
* `<[T]>::copy_from_slice`
* `ptr::read_volatile`
* `ptr::write_volatile`
* The `#[deprecated]` attribute
* `OpenOptions::create_new`

Deprecated

* `std::raw::Slice` - use raw parts of `slice` module instead
* `std::raw::Repr` - use raw parts of `slice` module instead
* `str::char_range_at` - use slicing plus `chars()` plus `len_utf8`
* `str::char_range_at_reverse` - use slicing plus `chars().rev()` plus `len_utf8`
* `str::char_at` - use slicing plus `chars()`
* `str::char_at_reverse` - use slicing plus `chars().rev()`
* `str::slice_shift_char` - use `chars()` plus `Chars::as_str`
* `CommandExt::session_leader` - use `before_exec` instead.

Closes #27719
cc #27751 (deprecating the `Slice` bits)
Closes #27754
Closes #27780
Closes #27809
Closes #27811
Closes #27830
Closes #28050
Closes #29453
Closes #29791
Closes #29935
Closes #30014
Closes #30752
Closes #31262
cc #31398 (still need to deal with `before_exec`)
Closes #31405
Closes #31572
Closes #31755
Closes #31756

2 files changed, 5 insertions, 2 deletions

diff --git a/src/libstd/sys/common/backtrace.rs b/src/libstd/sys/common/backtrace.rs
index 24e1a82a593..6f185437e50 100644
--- a/src/libstd/sys/common/backtrace.rs
+++ b/src/libstd/sys/common/backtrace.rs
@@ -131,7 +131,7 @@ pub fn demangle(writer: &mut Write, s: &str) -> io::Result<()> {
                 first = false;
             }
             let mut rest = inner;
-            while rest.char_at(0).is_numeric() {
+            while rest.chars().next().unwrap().is_numeric() {
                 rest = &rest[1..];
             }
             let i: usize = inner[.. (inner.len() - rest.len())].parse().unwrap();
diff --git a/src/libstd/sys/common/wtf8.rs b/src/libstd/sys/common/wtf8.rs
index f64f835e198..55e485e5811 100644
--- a/src/libstd/sys/common/wtf8.rs
+++ b/src/libstd/sys/common/wtf8.rs
@@ -191,8 +191,11 @@ impl Wtf8Buf {
             match item {
                 Ok(ch) => string.push_char(ch),
                 Err(surrogate) => {
+                    let surrogate = surrogate.unpaired_surrogate();
                     // Surrogates are known to be in the code point range.
-                    let code_point = unsafe { CodePoint::from_u32_unchecked(surrogate as u32) };
+                    let code_point = unsafe {
+                        CodePoint::from_u32_unchecked(surrogate as u32)
+                    };
                     // Skip the WTF-8 concatenation check,
                     // surrogate pairs are already decoded by decode_utf16
                     string.push_code_point_unchecked(code_point)