1# The Rust Programming Language
2
3This is the main source code repository for [Rust]. It contains the compiler,
4standard library, and documentation.
5
6[Rust]: https://www.rust-lang.org
7
8**Note: this README is for _users_ rather than _contributors_.
9If you wish to _contribute_ to the compiler, you should read the
10[Getting Started][gettingstarted] section of the rustc-dev-guide instead.**
11
12## Quick Start
13
14Read ["Installation"] from [The Book].
15
16["Installation"]: https://doc.rust-lang.org/book/ch01-01-installation.html
17[The Book]: https://doc.rust-lang.org/book/index.html
18
19## Installing from Source
20
21The Rust build system uses a Python script called `x.py` to build the compiler,
22which manages the bootstrapping process. It lives in the root of the project.
23
24The `x.py` command can be run directly on most systems in the following format:
25
26```sh
27./x.py <subcommand> [flags]
28```
29
30This is how the documentation and examples assume you are running `x.py`.
31
32Systems such as Ubuntu 20.04 LTS do not create the necessary `python` command by default when Python is installed that allows `x.py` to be run directly. In that case you can either create a symlink for `python` (Ubuntu provides the `python-is-python3` package for this), or run `x.py` using Python itself:
33
34```sh
35# Python 3
36python3 x.py <subcommand> [flags]
37
38# Python 2.7
39python2.7 x.py <subcommand> [flags]
40```
41
42More information about `x.py` can be found
43by running it with the `--help` flag or reading the [rustc dev guide][rustcguidebuild].
44
45[gettingstarted]: https://rustc-dev-guide.rust-lang.org/getting-started.html
46[rustcguidebuild]: https://rustc-dev-guide.rust-lang.org/building/how-to-build-and-run.html
47
48### Building on a Unix-like system
491. Make sure you have installed the dependencies:
50
51   * `g++` 5.1 or later or `clang++` 3.5 or later
52   * `python` 3 or 2.7
53   * GNU `make` 3.81 or later
54   * `cmake` 3.13.4 or later
55   * `ninja`
56   * `curl`
57   * `git`
58   * `ssl` which comes in `libssl-dev` or `openssl-devel`
59   * `pkg-config` if you are compiling on Linux and targeting Linux
60
612. Clone the [source] with `git`:
62
63   ```sh
64   git clone https://github.com/rust-lang/rust.git
65   cd rust
66   ```
67
68[source]: https://github.com/rust-lang/rust
69
703. Configure the build settings:
71
72    The Rust build system uses a file named `config.toml` in the root of the
73    source tree to determine various configuration settings for the build.
74    Copy the default `config.toml.example` to `config.toml` to get started.
75
76    ```sh
77    cp config.toml.example config.toml
78    ```
79
80    If you plan to use `x.py install` to create an installation, it is recommended
81    that you set the `prefix` value in the `[install]` section to a directory.
82
83    Create install directory if you are not installing in default directory
84
854. Build and install:
86
87    ```sh
88    ./x.py build && ./x.py install
89    ```
90
91    When complete, `./x.py install` will place several programs into
92    `$PREFIX/bin`: `rustc`, the Rust compiler, and `rustdoc`, the
93    API-documentation tool. This install does not include [Cargo],
94    Rust's package manager. To build and install Cargo, you may
95    run `./x.py install cargo` or set the `build.extended` key in
96    `config.toml` to `true` to build and install all tools.
97
98[Cargo]: https://github.com/rust-lang/cargo
99
100### Building on Windows
101
102There are two prominent ABIs in use on Windows: the native (MSVC) ABI used by
103Visual Studio, and the GNU ABI used by the GCC toolchain. Which version of Rust
104you need depends largely on what C/C++ libraries you want to interoperate with:
105for interop with software produced by Visual Studio use the MSVC build of Rust;
106for interop with GNU software built using the MinGW/MSYS2 toolchain use the GNU
107build.
108
109#### MinGW
110
111[MSYS2][msys2] can be used to easily build Rust on Windows:
112
113[msys2]: https://www.msys2.org/
114
1151. Grab the latest [MSYS2 installer][msys2] and go through the installer.
116
1172. Run `mingw32_shell.bat` or `mingw64_shell.bat` from wherever you installed
118   MSYS2 (i.e. `C:\msys64`), depending on whether you want 32-bit or 64-bit
119   Rust. (As of the latest version of MSYS2 you have to run `msys2_shell.cmd
120   -mingw32` or `msys2_shell.cmd -mingw64` from the command line instead)
121
1223. From this terminal, install the required tools:
123
124   ```sh
125   # Update package mirrors (may be needed if you have a fresh install of MSYS2)
126   pacman -Sy pacman-mirrors
127
128   # Install build tools needed for Rust. If you're building a 32-bit compiler,
129   # then replace "x86_64" below with "i686". If you've already got git, python,
130   # or CMake installed and in PATH you can remove them from this list. Note
131   # that it is important that you do **not** use the 'python2', 'cmake' and 'ninja'
132   # packages from the 'msys2' subsystem. The build has historically been known
133   # to fail with these packages.
134   pacman -S git \
135               make \
136               diffutils \
137               tar \
138               mingw-w64-x86_64-python \
139               mingw-w64-x86_64-cmake \
140               mingw-w64-x86_64-gcc \
141               mingw-w64-x86_64-ninja
142   ```
143
1444. Navigate to Rust's source code (or clone it), then build it:
145
146   ```sh
147   ./x.py build && ./x.py install
148   ```
149
150#### MSVC
151
152MSVC builds of Rust additionally require an installation of Visual Studio 2017
153(or later) so `rustc` can use its linker.  The simplest way is to get the
154[Visual Studio], check the “C++ build tools” and “Windows 10 SDK” workload.
155
156[Visual Studio]: https://visualstudio.microsoft.com/downloads/
157
158(If you're installing cmake yourself, be careful that “C++ CMake tools for
159Windows” doesn't get included under “Individual components”.)
160
161With these dependencies installed, you can build the compiler in a `cmd.exe`
162shell with:
163
164```sh
165python x.py build
166```
167
168Currently, building Rust only works with some known versions of Visual Studio. If
169you have a more recent version installed and the build system doesn't understand,
170you may need to force rustbuild to use an older version. This can be done
171by manually calling the appropriate vcvars file before running the bootstrap.
172
173```batch
174CALL "C:\Program Files (x86)\Microsoft Visual Studio\2019\Community\VC\Auxiliary\Build\vcvars64.bat"
175python x.py build
176```
177
178#### Specifying an ABI
179
180Each specific ABI can also be used from either environment (for example, using
181the GNU ABI in PowerShell) by using an explicit build triple. The available
182Windows build triples are:
183- GNU ABI (using GCC)
184    - `i686-pc-windows-gnu`
185    - `x86_64-pc-windows-gnu`
186- The MSVC ABI
187    - `i686-pc-windows-msvc`
188    - `x86_64-pc-windows-msvc`
189
190The build triple can be specified by either specifying `--build=<triple>` when
191invoking `x.py` commands, or by copying the `config.toml` file (as described
192in [Installing From Source](#installing-from-source)), and modifying the
193`build` option under the `[build]` section.
194
195### Configure and Make
196
197While it's not the recommended build system, this project also provides a
198configure script and makefile (the latter of which just invokes `x.py`).
199
200```sh
201./configure
202make && sudo make install
203```
204
205When using the configure script, the generated `config.mk` file may override the
206`config.toml` file. To go back to the `config.toml` file, delete the generated
207`config.mk` file.
208
209## Building Documentation
210
211If you’d like to build the documentation, it’s almost the same:
212
213```sh
214./x.py doc
215```
216
217The generated documentation will appear under `doc` in the `build` directory for
218the ABI used. I.e., if the ABI was `x86_64-pc-windows-msvc`, the directory will be
219`build\x86_64-pc-windows-msvc\doc`.
220
221## Notes
222
223Since the Rust compiler is written in Rust, it must be built by a
224precompiled "snapshot" version of itself (made in an earlier stage of
225development). As such, source builds require a connection to the Internet, to
226fetch snapshots, and an OS that can execute the available snapshot binaries.
227
228Snapshot binaries are currently built and tested on several platforms:
229
230| Platform / Architecture                     | x86 | x86_64 |
231|---------------------------------------------|-----|--------|
232| Windows (7, 8, 10, ...)                     | ✓   | ✓      |
233| Linux (kernel 2.6.32, glibc 2.11 or later)  | ✓   | ✓      |
234| macOS (10.7 Lion or later)                  | (\*) | ✓      |
235
236(\*): Apple dropped support for running 32-bit binaries starting from macOS 10.15 and iOS 11.
237Due to this decision from Apple, the targets are no longer useful to our users.
238Please read [our blog post][macx32] for more info.
239
240[macx32]: https://blog.rust-lang.org/2020/01/03/reducing-support-for-32-bit-apple-targets.html
241
242You may find that other platforms work, but these are our officially
243supported build environments that are most likely to work.
244
245## Getting Help
246
247The Rust community congregates in a few places:
248
249* [Stack Overflow] - Direct questions about using the language.
250* [users.rust-lang.org] - General discussion and broader questions.
251* [/r/rust] - News and general discussion.
252
253[Stack Overflow]: https://stackoverflow.com/questions/tagged/rust
254[/r/rust]: https://reddit.com/r/rust
255[users.rust-lang.org]: https://users.rust-lang.org/
256
257## Contributing
258
259If you are interested in contributing to the Rust project, please take a look
260at the [Getting Started][gettingstarted] guide in the [rustc-dev-guide].
261
262[rustc-dev-guide]: https://rustc-dev-guide.rust-lang.org
263
264## License
265
266Rust is primarily distributed under the terms of both the MIT license
267and the Apache License (Version 2.0), with portions covered by various
268BSD-like licenses.
269
270See [LICENSE-APACHE](LICENSE-APACHE), [LICENSE-MIT](LICENSE-MIT), and
271[COPYRIGHT](COPYRIGHT) for details.
272
273## Trademark
274
275[The Rust Foundation][rust-foundation] owns and protects the Rust and Cargo
276trademarks and logos (the “Rust Trademarks”).
277
278If you want to use these names or brands, please read the [media guide][media-guide].
279
280Third-party logos may be subject to third-party copyrights and trademarks. See
281[Licenses][policies-licenses] for details.
282
283[rust-foundation]: https://foundation.rust-lang.org/
284[media-guide]: https://www.rust-lang.org/policies/media-guide
285[policies-licenses]: https://www.rust-lang.org/policies/licenses
286