Merge upstream/master: Fix a weird bug

Author: ubsan

README.md

@@ -1,7 +1,7 @@
 # The Rust Programming Language
 
-This is the main source code repository for [Rust]. It contains the compiler, standard library,
-and documentation.
+This is the main source code repository for [Rust]. It contains the compiler,
+standard library, and documentation.
 
 [Rust]: https://www.rust-lang.org
 
@@ -64,37 +64,37 @@ build.
 
 #### MinGW
 
-[MSYS2](http://msys2.github.io/) can be used to easily build Rust on Windows:
+[MSYS2][msys2] can be used to easily build Rust on Windows:
 
-1. Grab the latest MSYS2 installer and go through the installer.
+msys2: https://msys2.github.io/
 
-2. From the MSYS2 terminal, install the `mingw64` toolchain and other required
-   tools.
+1. Grab the latest [MSYS2 installer][msys2] and go through the installer.
 
-   ```sh
-   # Update package mirrors (may be needed if you have a fresh install of MSYS2)
-   $ pacman -Sy pacman-mirrors
-   ```
+2. Run `mingw32_shell.bat` or `mingw64_shell.bat` from wherever you installed
+   MSYS2 (i.e. `C:\msys64`), depending on whether you want 32-bit or 64-bit
+   Rust. (As of the latest version of MSYS2 you have to run `msys2_shell.cmd
+   -mingw32` or `msys2_shell.cmd -mingw64` from the command line instead)
 
-   Download [MinGW from
-   here](http://mingw-w64.org/doku.php/download/mingw-builds), and choose the
-   `version=4.9.x,threads=win32,exceptions=dwarf/seh` flavor when installing. Also, make sure to install to a path without spaces in it. After installing,
-   add its `bin` directory to your `PATH`. This is due to [#28260](https://github.com/rust-lang/rust/issues/28260), in the future,
-   installing from pacman should be just fine.
+3. From this terminal, install the required tools:
 
    ```sh
-   # Make git available in MSYS2 (if not already available on path)
-   $ pacman -S git
+   # Update package mirrors (may be needed if you have a fresh install of MSYS2)
+   $ pacman -Sy pacman-mirrors
 
-   $ pacman -S base-devel
+   # Install build tools needed for Rust. If you're building a 32-bit compiler,
+   # then replace "x86_64" below with "i686". If you've already got git, python,
+   # or CMake installed and in PATH you can remove them from this list. Note
+   # that it is important that the `python2` and `cmake` packages **not** used.
+   # The build has historically been known to fail with these packages.
+   $ pacman -S git \
+               make \
+               diffutils \
+               mingw-w64-x86_64-python2 \
+               mingw-w64-x86_64-cmake \
+               mingw-w64-x86_64-gcc
    ```
 
-3. Run `mingw32_shell.bat` or `mingw64_shell.bat` from wherever you installed
-   MSYS2 (i.e. `C:\msys`), depending on whether you want 32-bit or 64-bit Rust.
-   (As of the latest version of MSYS2 you have to run `msys2_shell.cmd -mingw32`
-   or `msys2_shell.cmd -mingw64` from the command line instead)
-
-4. Navigate to Rust's source code, configure and build it:
+4. Navigate to Rust's source code (or clone it), then configure and build it:
 
    ```sh
    $ ./configure
@@ -114,12 +114,25 @@ $ ./configure
 $ make && make install
 ```
 
+#### MSVC with rustbuild
+
+For those who don't want the hassle of MSYS or MinGW, you can invoke rustbuild
+directly. All you need are Python 2, CMake, and Git in your PATH (make sure you
+do __not__ use the ones from MSYS!). You'll also need Visual Studio 2013 or
+newer with the C++ tools. Then all you need to do is invoke the appropriate
+vcvars bat file and kick off rustbuild.
+
+```bat
+CALL "C:\Program Files (x86)\Microsoft Visual Studio 14.0\VC\bin\amd64\vcvars64.bat"
+python .\src\bootstrap\bootstrap.py
+```
+
 ## Building Documentation
 
 If you’d like to build the documentation, it’s almost the same:
 
 ```sh
-./configure
+$ ./configure
 $ make docs
 ```
 
@@ -154,8 +167,8 @@ Snapshot binaries are currently built and tested on several platforms:
 You may find that other platforms work, but these are our officially
 supported build environments that are most likely to work.
 
-Rust currently needs between 600MiB and 1.5GiB to build, depending on platform. If it hits
-swap, it will take a very long time to build.
+Rust currently needs between 600MiB and 1.5GiB to build, depending on platform.
+If it hits swap, it will take a very long time to build.
 
 There is more advice about hacking on Rust in [CONTRIBUTING.md].
 
@@ -192,4 +205,5 @@ Rust is primarily distributed under the terms of both the MIT license
 and the Apache License (Version 2.0), with portions covered by various
 BSD-like licenses.
 
-See [LICENSE-APACHE](LICENSE-APACHE), [LICENSE-MIT](LICENSE-MIT), and [COPYRIGHT](COPYRIGHT) for details.
+See [LICENSE-APACHE](LICENSE-APACHE), [LICENSE-MIT](LICENSE-MIT), and
+[COPYRIGHT](COPYRIGHT) for details.