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

Note: this README is forusers rather thancontributors.If you wish tocontribute to the compiler, you should readCONTRIBUTING.md instead.

Read"Installation" fromThe Book.

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

Thex.py command can be run directly on most Unix systems in the followingformat:

./x.py<subcommand> [flags]

This is how the documentation and examples assume you are runningx.py.Some alternative ways are:

# On a Unix shell if you don't have the necessary `python3` command./x<subcommand> [flags]# On the Windows Command Prompt (if .py files are configured to run Python)x.py<subcommand> [flags]# You can also run Python yourself, e.g.:python x.py<subcommand> [flags]

More information aboutx.py can be found by running it with the--help flagor reading therustc dev guide.

Make sure you have installed the dependencies:

• python 3 or 2.7
• git
• A C compiler (when building for the host,cc is enough; cross-compiling mayneed additional compilers)
• curl (not needed on Windows)
• pkg-config if you are compiling on Linux and targeting Linux
• libiconv (already included with glibc on Debian-based distros)

To build Cargo, you'll also need OpenSSL (libssl-dev oropenssl-devel onmost Unix distros).

If building LLVM from source, you'll need additional tools:

• g++,clang++, or MSVC with versions listed onLLVM's documentation
• ninja, or GNUmake 3.81 or later (Ninja is recommended, especially onWindows)
• cmake 3.13.4 or later
• libstdc++-static may be required on some Linux distributions such as Fedoraand Ubuntu

On tier 1 or tier 2 with host tools platforms, you can also choose to downloadLLVM by settingllvm.download-ci-llvm = true.Otherwise, you'll need LLVM installed andllvm-config in your path.Seethe rustc-dev-guide for more info.

1. Clone thesource withgit:

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

2. Configure the build settings:

   The Rust build system uses a file namedconfig.toml in the root of thesource tree to determine various configuration settings for the build.Set up the defaults intended for distros to get started. You can see a fulllist of options inconfig.example.toml.

   printf'profile = "user" \nchangelog-seen = 2 \n'> config.toml

   If you plan to usex.py install to create an installation, it isrecommended that you set theprefix value in the[install] section to adirectory.

3. 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, andrustdoc, theAPI-documentation tool. If you've setprofile = "user" orbuild.extended = true, it will also includeCargo, Rust's packagemanager.

On Windows, we suggest usingwinget to install dependencies by running thefollowing in a terminal:

winget install-e Python.Python.3winget install-e Kitware.CMakewinget install-e Git.Git

Then edit your system'sPATH variable and add:C:\Program Files\CMake\bin.Seethis guide on editing the systemPATHfrom the Java documentation.

There are two prominent ABIs in use on Windows: the native (MSVC) ABI used byVisual Studio and the GNU ABI used by the GCC toolchain. Which version of Rustyou 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 Studioand the GNU build to interop with GNU software built using the MinGW/MSYS2toolchain.

MSYS2 can be used to easily build Rust on Windows:

1. Download the latestMSYS2 installer and go through the installer.

2. Runmingw32_shell.bat ormingw64_shell.bat from the MSYS2 installationdirectory (e.g.C:\msys64), depending on whether you want 32-bit or 64-bitRust. (As of the latest version of MSYS2 you have to runmsys2_shell.cmd -mingw32 ormsys2_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 builds of Rust additionally require an installation of Visual Studio 2017(or later) sorustc can use its linker. The simplest way is to getVisual Studio, check the "C++ build tools" and "Windows 10 SDK" workload.

(If you're installing CMake yourself, be careful that "C++ CMake tools forWindows" doesn't get included under "Individual components".)

With these dependencies installed, you can build the compiler in acmd.exeshell 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'tunderstand, you may need to force rustbuild to use an older version.This can be done by manually calling the appropriate vcvars file before runningthe bootstrap.

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

Each specific ABI can also be used from either environment (for example, usingthe GNU ABI in PowerShell) by using an explicit build triple. The availableWindows 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> wheninvokingx.py commands, or by creating aconfig.toml file (as described inInstalling from Source), and modifying thebuildoption under the[build] section.

While it's not the recommended build system, this project also provides aconfigure script and makefile (the latter of which just invokesx.py).

./configuremake&& sudo make install

configure generates aconfig.toml which can also be used with normalx.pyinvocations.

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

./x.py doc

The generated documentation will appear underdoc in thebuild directory forthe ABI used. That is, if the ABI wasx86_64-pc-windows-msvc, the directorywill bebuild\x86_64-pc-windows-msvc\doc.

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 anOS that can execute the available snapshot binaries.

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

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

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

SeeCONTRIBUTING.md.

Rust is primarily distributed under the terms of both the MIT license and theApache License (Version 2.0), with portions covered by various BSD-likelicenses.

SeeLICENSE-APACHE,LICENSE-MIT, andCOPYRIGHT for details.

The Rust Foundation owns and protects the Rust and Cargotrademarks and logos (the "Rust Trademarks").

If you want to use these names or brands, please read themedia guide.

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