rust/README.md

# The Rust Programming Language

This is the main source code repository for [Rust]. It contains the compiler,
standard library, and documentation.

[Rust]: https://www.rust-lang.org

## Quick Start
[quick-start]: #quick-start

Read ["Installation"] from [The Book].

["Installation"]: https://doc.rust-lang.org/book/ch01-01-installation.html
[The Book]: https://doc.rust-lang.org/book/index.html

## Installing from Source
[building-from-source]: #building-from-source

_Note: If you wish to contribute to the compiler, you should read
[this chapter](https://rust-lang.github.io/rustc-guide/how-to-build-and-run.html)
of the rustc-guide instead._

### Building on *nix
1. Make sure you have installed the dependencies:

   * `g++` 4.7 or later or `clang++` 3.x or later
   * `python` 2.7 (but not 3.x)
   * GNU `make` 3.81 or later
   * `cmake` 3.4.3 or later
   * `curl`
   * `git`

2. Clone the [source] with `git`:

   ```sh
   $ git clone https://github.com/rust-lang/rust.git
   $ cd rust
   ```

[source]: https://github.com/rust-lang/rust

3. Build and install:

    ```sh
    $ ./x.py build && sudo ./x.py install
    ```

    If after running `sudo ./x.py install` you see an error message like

    ```
    error: failed to load source for a dependency on 'cc'
    ```

    then run these two commands and then try `sudo ./x.py install` again:

    ```
    $ cargo install cargo-vendor
    ```

    ```
    $ cargo vendor
    ```

    > ***Note:*** Install locations can be adjusted by copying the config file
    > from `./config.toml.example` to `./config.toml`, and
    > adjusting the `prefix` option under `[install]`. Various other options, such
    > as enabling debug information, are also supported, and are documented in
    > the config file.

    When complete, `sudo ./x.py install` will place several programs into
    `/usr/local/bin`: `rustc`, the Rust compiler, and `rustdoc`, the
    API-documentation tool. This install does not include [Cargo],
    Rust's package manager, which you may also want to build.

[Cargo]: https://github.com/rust-lang/cargo

### Building on Windows
[building-on-windows]: #building-on-windows

There are two prominent ABIs in use on Windows: the native (MSVC) ABI used by
Visual Studio, and the GNU ABI used by the GCC toolchain. Which version of Rust
you need depends largely on what C/C++ libraries you want to interoperate with:
for interop with software produced by Visual Studio use the MSVC build of Rust;
for interop with GNU software built using the MinGW/MSYS2 toolchain use the GNU
build.

#### MinGW
[windows-mingw]: #windows-mingw

[MSYS2][msys2] can be used to easily build Rust on Windows:

[msys2]: https://msys2.github.io/

1. Grab the latest [MSYS2 installer][msys2] and go through the installer.

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)

3. From this terminal, install the required tools:

   ```sh
   # Update package mirrors (may be needed if you have a fresh install of MSYS2)
   $ pacman -Sy pacman-mirrors

   # 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 you do **not** use the 'python2' and 'cmake'
   # packages from the 'msys2' subsystem. The build has historically been known
   # to fail with these packages.
   $ pacman -S git \
               make \
               diffutils \
               tar \
               mingw-w64-x86_64-python2 \
               mingw-w64-x86_64-cmake \
               mingw-w64-x86_64-gcc
   ```

4. Navigate to Rust's source code (or clone it), then build it:

   ```sh
   $ ./x.py build && ./x.py install
   ```

#### MSVC
[windows-msvc]: #windows-msvc

MSVC builds of Rust additionally require an installation of Visual Studio 2017
(or later) so `rustc` can use its linker.  The simplest way is to get the
[Visual Studio Build Tools] and check the “C++ build tools” workload.

[Visual Studio Build Tools]: https://visualstudio.microsoft.com/downloads/#build-tools-for-visual-studio-2019

At last check (cmake 3.14.3 and msvc 16.0.3) using the 2019 tools fails to
build the in-tree LLVM build with a CMake error, so use 2017 instead by
including the “MSVC v141 – VS 2017 C++ x64/x86 build tools (v14.16)” component.

With these dependencies installed, you can build the compiler in a `cmd.exe`
shell with:

```sh
> python x.py build
```

Currently, building Rust only works with some known versions of Visual Studio. If
you have a more recent version installed the build system doesn't understand
then you may need to force rustbuild to use an older version. This can be done
by manually calling the appropriate vcvars file before running the bootstrap.

```batch
> CALL "C:\Program Files (x86)\Microsoft Visual Studio 14.0\VC\bin\amd64\vcvars64.bat"
> python x.py build
```

#### Specifying an ABI
[specifying-an-abi]: #specifying-an-abi

Each specific ABI can also be used from either environment (for example, using
the GNU ABI in PowerShell) by using an explicit build triple. The available
Windows build triples are:
- GNU ABI (using GCC)
    - `i686-pc-windows-gnu`
    - `x86_64-pc-windows-gnu`
- The MSVC ABI
    - `i686-pc-windows-msvc`
    - `x86_64-pc-windows-msvc`

The build triple can be specified by either specifying `--build=<triple>` when
invoking `x.py` commands, or by copying the `config.toml` file (as described
in Building From Source), and modifying the `build` option under the `[build]`
section.

### Configure and Make
[configure-and-make]: #configure-and-make

While it's not the recommended build system, this project also provides a
configure script and makefile (the latter of which just invokes `x.py`).

```sh
$ ./configure
$ make && sudo make install
```

When using the configure script, the generated `config.mk` file may override the
`config.toml` file. To go back to the `config.toml` file, delete the generated
`config.mk` file.

## Building Documentation
[building-documentation]: #building-documentation

If you’d like to build the documentation, it’s almost the same:

```sh
$ ./x.py doc
```

The generated documentation will appear under `doc` in the `build` directory for
the ABI used. I.e., if the ABI was `x86_64-pc-windows-msvc`, the directory will be
`build\x86_64-pc-windows-msvc\doc`.

## Notes
[notes]: #notes

Since the Rust compiler is written in Rust, it must be built by a
precompiled "snapshot" version of itself (made in an earlier stage of
development). As such, source builds require a connection to the Internet, to
fetch snapshots, and an OS that can execute the available snapshot binaries.

Snapshot binaries are currently built and tested on several platforms:

| Platform / Architecture  | x86 | x86_64 |
|--------------------------|-----|--------|
| Windows (7, 8, 10, ...)  | ✓   | ✓      |
| Linux (2.6.18 or later)  | ✓   | ✓      |
| OSX (10.7 Lion or later) | ✓   | ✓      |

You may find that other platforms work, but these are our officially
supported build environments that are most likely to work.

There is more advice about hacking on Rust in [CONTRIBUTING.md].

[CONTRIBUTING.md]: https://github.com/rust-lang/rust/blob/master/CONTRIBUTING.md

## Getting Help
[getting-help]: #getting-help

The Rust community congregates in a few places:

* [Stack Overflow] - Direct questions about using the language.
* [users.rust-lang.org] - General discussion and broader questions.
* [/r/rust] - News and general discussion.

[Stack Overflow]: https://stackoverflow.com/questions/tagged/rust
[/r/rust]: https://reddit.com/r/rust
[users.rust-lang.org]: https://users.rust-lang.org/

## Contributing
[contributing]: #contributing

To contribute to Rust, please see [CONTRIBUTING](CONTRIBUTING.md).

Rust has an [IRC] culture and most real-time collaboration happens in a
variety of channels on Mozilla's IRC network, irc.mozilla.org. The
most popular channel is [#rust], a venue for general discussion about
Rust. And a good place to ask for help would be [#rust-beginners].

The [rustc guide] might be a good place to start if you want to find out how
various parts of the compiler work.

Also, you may find the [rustdocs for the compiler itself][rustdocs] useful.

[IRC]: https://en.wikipedia.org/wiki/Internet_Relay_Chat
[#rust]: irc://irc.mozilla.org/rust
[#rust-beginners]: irc://irc.mozilla.org/rust-beginners
[rustc guide]: https://rust-lang.github.io/rustc-guide/about-this-guide.html
[rustdocs]: https://doc.rust-lang.org/nightly/nightly-rustc/rustc/

## License
[license]: #license

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.

## Trademark
[trademark]: #trademark

The Rust programming language is an open source, community project governed
by a core team. It is also sponsored by the Mozilla Foundation (“Mozilla”),
which owns and protects the Rust and Cargo trademarks and logos
(the “Rust Trademarks”).

If you want to use these names or brands, please read the [media guide][media-guide].

Third-party logos may be subject to third-party copyrights and trademarks. See
[Licenses][policies-licenses] for details.

[media-guide]: https://www.rust-lang.org/policies/media-guide
[policies-licenses]: https://www.rust-lang.org/policies/licenses