rust/README.md

The Rust Programming Language

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

**Note: this README is for users rather than contributors. If you wish to contribute to the compiler, you should read CONTRIBUTING.md instead.

Quick Start

Read "Installation" from The Book.

Installing from Source

The Rust build system uses a Python script called x.py to build the compiler, which manages the bootstrapping process. It lives at the root of the project.

The x.py command can be run directly on most systems in the following format:

./x.py <subcommand> [flags]

This is how the documentation and examples assume you are running x.py.

Systems 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:

# Python 3
python3 x.py <subcommand> [flags]

# Python 2.7
python2.7 x.py <subcommand> [flags]

More information about x.py can be found by running it with the --help flag or reading the rustc dev guide.

Building on a Unix-like system

1. Make sure you have installed the dependencies:

   • g++ 5.1 or later or clang++ 3.5 or later
   • python 3 or 2.7
   • GNU make 3.81 or later
   • cmake 3.13.4 or later
   • ninja
   • curl
   • git
   • ssl which comes in libssl-dev or openssl-devel
   • pkg-config if you are compiling on Linux and targeting Linux

2. Clone the source with git:

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

3. Configure the build settings:

   The Rust build system uses a file named config.toml in the root of the source tree to determine various configuration settings for the build. Copy the default config.toml.example to config.toml to get started.

   cp config.toml.example config.toml
   

   If you plan to use x.py install to create an installation, it is recommended that you set the prefix value in the [install] section to a directory.

   Create an install directory if you are not installing in the default directory.

4. Build and install:

   ./x.py build && ./x.py install
   

   When complete, ./x.py install will place several programs into $PREFIX/bin: rustc, the Rust compiler, and rustdoc, the API-documentation tool. This install does not include Cargo, Rust's package manager. To build and install Cargo, you may run ./x.py install cargo or set the build.extended key in config.toml to true to build and install all tools.

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. Use the MSVC build of Rust to interop with software produced by Visual Studio and the GNU build to interop with GNU software built using the MinGW/MSYS2 toolchain.

MinGW

MSYS2 can be used to easily build Rust on Windows:

1. Download the latest MSYS2 installer and go through the installer.

2. Run mingw32_shell.bat or mingw64_shell.bat from the MSYS2 installation directory (e.g. 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:

   # 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', 'cmake' and 'ninja'
   # 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-python \
               mingw-w64-x86_64-cmake \
               mingw-w64-x86_64-gcc \
               mingw-w64-x86_64-ninja
   

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

   ./x.py build && ./x.py install
   

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 Visual Studio, check the “C++ build tools” and “Windows 10 SDK” workload.

(If you're installing cmake yourself, be careful that “C++ CMake tools for Windows” doesn't get included under “Individual components”.)

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

python x.py build

Right now, building Rust only works with some known versions of Visual Studio. If you have a more recent version installed and the build system doesn't understand, 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.

CALL "C:\Program Files (x86)\Microsoft Visual Studio\2019\Community\VC\Auxiliary\Build\vcvars64.bat"
python x.py build

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 Installing From Source), and modifying the build option under the [build] section.

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).

./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

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

./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

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 an Internet connection to fetch snapshots, and an OS that can execute the available snapshot binaries.

See https://doc.rust-lang.org/nightly/rustc/platform-support.html for a list of supported platforms. Only "host tools" platforms have a pre-compiled snapshot binary available; to compile for a platform without host tools you must cross-compile.

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

Getting Help

See https://www.rust-lang.org/community for a list of chat platforms and forums.

Contributing

See CONTRIBUTING.md.

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-MIT, and COPYRIGHT for details.

Trademark

The Rust Foundation 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.

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