Added functions pop_char and shift_char to StrBuf struct along with appropriate unit tests, using the same test case as push_char.

Changed StrBuf.shift_byte() that it no longer reallocates the buffer by just calling Vec.shift();

Added warning to shift_char()'s docs about it having to copy the whole buffer, as per the docs for
Vec.shift().
auto merge of #14052 : dylanbraithwaite/rust/char-fns-for-strbuf, r=alexcrichton

Added functions pop_char and shift_char to StrBuf along with unit tests, using the same test cases as push_char.
Use CreateProcessW instead of CreateProcessA

Changed libnative to use CreateProcessW instead of CreateProcessA.  In
addition, the lpEnvironment parameter now uses Unicode.

Added a helper function os::win32::as_mut_utf16_p, which does basically
the same thing as os::win32::as_utf16_p except the pointer is mutable.
Fix make_command_line to handle Unicode correctly

Previously, make_command_line iterates over each u8 in the string and
then appends them as chars, so any non-ASCII string will get horribly
mangled by this function.  This fix should allow Unicode arguments to
work correctly in native::io::process::spawn.
Use Get/FreeEnvironmentStringsW instead of Get/FreeEnvironmentStringsA

Changed libstd to use Get/FreeEnvironmentStringsW instead of
Get/FreeEnvironmentStringsA to support Unicode environment variables.
Test Unicode support of process spawning

Added a run-pass test to ensure that processes can be correctly spawned
using non-ASCII arguments, working directory, and environment variables.
It also tests Unicode support of os::env_as_bytes.

An additional assertion was added to the test for make_command_line to
verify it handles Unicode correctly.
auto merge of #14075 : Rufflewind/rust/patch-3, r=alexcrichton

- Use Unicode-aware versions of `CreateProcess` (Fixes #13815) and `Get/FreeEnvironmentStrings`.
    - Includes a helper function `os::win32::as_mut_utf16_p`, which does the same thing as `os::win32::as_utf16_p` except the pointer is mutable.
    - Fixed `make_command_line` to handle Unicode correctly.
- Tests for the above.
std: Move the owned module from core to std

The compiler was updated to recognize that implementations for ty_uniq(..) are
allowed if the Box lang item is located in the current crate. This enforces the
idea that libcore cannot allocated, and moves all related trait implementations
from libcore to libstd.

This is a breaking change in that the AnyOwnExt trait has moved from the any
module to the owned module. Any previous users of std::any::AnyOwnExt should now
use std::owned::AnyOwnExt instead. This was done because the trait is intended
for Box traits and only Box traits.

[breaking-change]
Allow blocks in const expressions

Only blocks with tail expressions that are const expressions
and items are allowed.
Add tests for from_bits.

Signed-off-by: OGINO Masanori <masanori.ogino@gmail.com>
Replaced ~T by Box<T> in manual
Implements Default trait for BigInt and BigUint
Fix #8391

Closes #8391
check_match: get rid of superfluous clones
std, core: Generate unicode.rs using unicode.py
core: Use appropriately sized integers for codepoints and bytes
core: Move Hangul decomposition into unicode.rs
std: Rename str::Normalizations to str::Decompositions

The Normalizations iterator has been renamed to Decompositions.
It does not currently include all forms of Unicode normalization,
but only encompasses decompositions.
If implemented recomposition would likely be a separate iterator
which works on the result of this one.

[breaking-change]
docs: Add a not found page
add a line to the example to clarify semantics

This is to clarify that match construct doesn't define a new variable, since I
observed a person reading the Rust tutorial who seemed to incorrectly think
that it did. Fixes https://github.com/mozilla/rust/issues/13571 .