Before building the compiler, you need the following things installed:
python3 or 2.7 (under the name
python3will not work)
sslwhich comes in
pkg-configif you are compiling on Linux and targeting Linux
If building LLVM from source (the default), you'll need additional tools:
g++5.1 or later,
clang++3.5 or later, or MSVC 2017 or later.
ninja, or GNU
make3.81 or later (ninja is recommended, especially on Windows)
cmake3.13.4 or later
Otherwise, you'll need LLVM installed and
llvm-config in your path.
See this section for more info.
- Install winget
winget is a Windows package manager. It will make package installation easy
Run the following in a terminal:
winget install python winget install cmake
If any of those is installed already, winget will detect it.
Then edit your systems
PATH variable and add:
For more information about building on Windows,
You will need an internet connection to build. The bootstrapping process involves updating git submodules and downloading a beta compiler. It doesn't need to be super fast, but that can help.
There are no strict hardware requirements, but building the compiler is computationally expensive, so a beefier machine will help, and I wouldn't recommend trying to build on a Raspberry Pi! We recommend the following.
- 30GB+ of free disk space. Otherwise, you will have to keep clearing incremental caches. More space is better, the compiler is a bit of a hog; it's a problem we are aware of.
- 8GB+ RAM
- 2+ cores. Having more cores really helps. 10 or 20 or more is not too many!
Beefier machines will lead to much faster builds. If your machine is not very
powerful, a common strategy is to only use
./x.py check on your local machine
and let the CI build test your changes when you push to a PR branch.
Building the compiler takes more than half an hour on my moderately powerful laptop. The first time you build the compiler, LLVM will also be built unless you use CI-built LLVM (see here).
cargo, the build system will use as many cores as possible. Sometimes
this can cause you to run low on memory. You can use
-j to adjust the number
concurrent jobs. If a full build takes more than ~45 minutes to an hour, you
are probably spending most of the time swapping memory in and out; try using
If you don't have too much free disk space, you may want to turn off incremental compilation (see here). This will make compilation take longer (especially after a rebase), but will save a ton of space from the incremental caches.
Follow the installation given in the Rust book to install a working
rustc and the necessary C/++ toolchain on your platform.