bors 185de5f41a Auto merge of #79540 - jyn514:no-xpy, r=Mark-Simulacrum
Allow building rustdoc without first building rustc (MVP)

 ## Motivation

The compile times for rustc are extremely long and a major issue for
recruiting new contributors to rustdoc. People interested in joining
often give up after running into issues with submodules or python
versions. stage1 rustdoc fundamentally doesn't care about bootstrapping
or stages, it just needs `rustc_private` available.

## Summary of Changes

- Add an opt-in `[rust] download_rustc` option
- Determine the version of the compiler to download using `log --author=bors`
- Do no work for any component other than `Rustdoc` for any stage. Instead, copy the CI artifacts from the downloaded sysroot stage0/ to stage0-sysroot/ or stage1/ in `Sysroot`. This is done with an `ENABLE_DOWNLOAD_STAGE1` constant which is off by default.
- Don't download different versions of rustfmt or cargo - those should still use the beta version (rustfmt especially).

The vast majority of work is done in bootstrap.py, which downloads the artifacts and extracts them to stage0/ in place of the beta compiler. Rustbuild just takes care of copying the artifacts to stage1 if necessary.

## Future work

- I turned off verification for the commit tarballs because the .sha256 URLs gave a 404. This seems not ideal, it would be nice to start signing them.
- This will break if you rebase an old enough branch (I think commits are kept at most 160 days?). This doesn't need to be supported, but it would be nice to give a reasonable error. https://github.com/rust-lang/rust/pull/79540#issuecomment-751481291
- Right now, every time you rebase, stage0 tools (bootstrap, tidy, ...) will have to be recompiled. Additionally running `x.py setup tools` will compile rustbuild twice. Instead, this should download a separate beta compiler for stage0 and only use CI artifacts for stage1 onward. https://github.com/rust-lang/rust/pull/79540#issuecomment-757047321
- Add `x.py setup tools` to enable this conveniently (it doesn't make sense to use this for compiler developers). cb5d8c8522
- Compile a new version of tracing so that rustdoc still gets debug logging (since CI artifacts always disable `debug` and `trace` logging). https://github.com/rust-lang/rust/pull/79540#issuecomment-742756411, 6a5d512420
- Right now only rustdoc is ever rebuilt. This is not ideal and should probably at least compile compiler tools (rustfmt, clippy, miri). https://github.com/rust-lang/rust/pull/79540#issuecomment-775634693
- Using `git log --author=bors` sometimes breaks. This should use `git merge-base` instead. https://github.com/rust-lang/rust/pull/79540#discussion_r572572280
- It would be nice to support cross-compiling the standard library. Right now this gives an assertion failure I think.

Some of this work has already been done in (the history for) 673476c785.
2021-02-09 15:28:28 +00:00

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 the Getting Started section of the rustc-dev-guide 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. More information about it can be found by running ./x.py --help 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 3.4.3 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
    
  1. 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 install directory if you are not installing in default directory

  2. 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: 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

MSYS2 can be used to easily build Rust on Windows:

  1. Grab the latest MSYS2 installer 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:

    # 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 the 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

Currently, 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 youd like to build the documentation, its 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 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 (kernel 2.6.32, glibc 2.11 or later)
macOS (10.7 Lion or later) (*)

(*): Apple dropped support for running 32-bit binaries starting from macOS 10.15 and iOS 11. Due to this decision from Apple, the targets are no longer useful to our users. Please read our blog post for more info.

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

Getting Help

The Rust community congregates in a few places:

Contributing

If you are interested in contributing to the Rust project, please take a look at the Getting Started guide in the rustc-dev-guide.

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 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.

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

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