roc/BUILDING_FROM_SOURCE.md

Building the Roc compiler from source

Installation should be a smooth process, let us now if anything does not work perfectly on Roc Zulip or by creating an issue.

Using Nix

We highly recommend Using nix to quickly install all dependencies necessary to build roc.

On Linux x86_64/aarch64 or MacOS aarch64/arm64/x86_64

Install

If you are running ArchLinux or a derivative like Manjaro, you'll need to run sudo sysctl -w kernel.unprivileged_userns_clone=1 before installing nix.

Install nix (not necessary on NixOS):

sh <(curl -L https://nixos.org/nix/install) --daemon

Open a new terminal and install nixFlakes in your environment:

nix-env -iA nixpkgs.nixFlakes

Edit either ~/.config/nix/nix.conf or /etc/nix/nix.conf and add:

experimental-features = nix-command flakes

If Nix was installed in multi-user mode, make sure to restart the nix-daemon. If you don't know how to do this, restarting your computer will also do the job.

Usage

Now with nix set up, you just need to run one command from the roc project root directory:

nix develop

You should be in a shell with everything needed to build already installed. Use cargo run help to see all subcommands. To use the repl subcommand, execute cargo run repl. Use cargo build to build the whole project.

Read the instructions here to make nix work well with your development tools (vscode, vim, rust-analyzer...)

Extra tips

If you want to load all dependencies automatically whenever you cd into roc, check out direnv. Then you will no longer need to execute nix develop first.

Editor

The editor is a 🚧WIP🚧 and not ready yet to replace your favorite editor, although if you want to try it out on nix, read on. cargo run edit should work on NixOS and MacOS. If you use Linux x86_64, follow the instructions below.

If you're not already in a nix shell, execute nix develop at the the root of the repo folder and then execute:

nixVulkanIntel cargo run edit

Troubleshooting

Create an issue if you run into problems not listed here. That will help us improve this document for everyone who reads it in the future!

Manual Install

To build the compiler, you need these installed:

• Zig, see below for version
• libxkbcommon - macOS seems to have it already; on Ubuntu or Debian you can get it with apt-get install libxkbcommon-dev
• On Debian/Ubuntu sudo apt-get install pkg-config
• LLVM, see below for version
• rust
• Also run cargo install bindgen after installing rust. You may need to open a new terminal.

To run the test suite (via cargo test), you additionally need to install:

• valgrind (needs special treatment to install on macOS Alternatively, you can use cargo test --no-fail-fast or cargo test -p specific_tests to skip over the valgrind failures & tests.

For debugging LLVM IR, we use DebugIR. This dependency is only required to build with the --debug flag, and for normal development you should be fine without it.

libxcb libraries

You may see an error like this during builds:

/usr/bin/ld: cannot find -lxcb-render
/usr/bin/ld: cannot find -lxcb-shape
/usr/bin/ld: cannot find -lxcb-xfixes

If so, you can fix it like so:

sudo apt-get install libxcb-render0-dev libxcb-shape0-dev libxcb-xfixes0-dev

Zig

version: 0.9.1

For any OS, you can use zigup to manage zig installations.

If you prefer a package manager, you can try the following:

• For MacOS, you can install with brew install zig
• For, Ubuntu, you can use Snap, you can install with snap install zig --classic --beta
• For other systems, checkout this page

If you want to install it manually, you can also download Zig directly here. Just make sure you download the right version, the bleeding edge master build is the first download link on this page.

LLVM

version: 13.0.x

For macOS, you can install LLVM 13 using brew install llvm@13 and then adding $(brew --prefix llvm@13)/bin to your PATH. You can confirm this worked by running llc --version - it should mention "LLVM version 13.0.0" at the top. You may also need to manually specify a prefix env var like so:

export LLVM_SYS_130_PREFIX=/usr/local/opt/llvm@13

For Ubuntu and Debian:

sudo apt -y install lsb-release software-properties-common gnupg
wget https://apt.llvm.org/llvm.sh
chmod +x llvm.sh
./llvm.sh 13

If you use this script, you'll need to add clang to your PATH. By default, the script installs it as clang-13. You can address this with symlinks like so:

sudo ln -s /usr/bin/clang-13 /usr/bin/clang

There are also alternative installation options at http://releases.llvm.org/download.html

Troubleshooting

Building

Use cargo build to build the whole project. Use cargo run help to see all subcommands. To use the repl subcommand, execute cargo run repl.

LLVM installation on Linux

For a current list of all dependency versions and their names in apt, see the Earthfile.

On some Linux systems we've seen the error "failed to run custom build command for x11". On Ubuntu, running sudo apt install pkg-config cmake libx11-dev fixed this.

If you encounter cannot find -lz run sudo apt install zlib1g-dev.

If you encounter:

error: No suitable version of LLVM was found system-wide or pointed
       to by LLVM_SYS_130_PREFIX.

Add export LLVM_SYS_130_PREFIX=/usr/lib/llvm-13 to your ~/.bashrc or equivalent file for your shell.

LLVM installation on macOS

If installing LLVM fails, it might help to run sudo xcode-select -r before installing again.

It might also be useful to add these exports to your shell:

export LDFLAGS="-L/usr/local/opt/llvm/lib -Wl,-rpath,/usr/local/opt/llvm/lib"
export CPPFLAGS="-I/usr/local/opt/llvm/include"

LLVM installation on Windows

Warning While cargo build works on windows, linking roc programs does not yet, see issue #2608. This also means the repl, the editor and many tests will not work on windows. Installing LLVM's prebuilt binaries doesn't seem to be enough for the llvm-sys crate that Roc depends on, so I had to follow the steps below:

1. I downloaded and installed Build Tools for Visual Studio 2019 (a full Visual Studio install should work too; the Build Tools are just the CLI tools, which is all I wanted)
2. Download the custom LLVM 7z archive here.
3. Download 7-zip to be able to extract this archive.
4. Extract the 7z file to where you want to permanently keep the folder.
5. In powershell, set the LLVM_SYS_130_PREFIX environment variable (check here to make this a permanent environment variable):

[Environment]::SetEnvironmentVariable(
   "Path",
   [Environment]::GetEnvironmentVariable("Path", "User") + ";C:\Users\anton\Downloads\LLVM-13.0.0-win64\bin",
   "User"
)

Once all that was done, cargo build ran successfully for Roc!

Build speed on WSL/WSL2

If your Roc project folder is in the Windows filesystem but you're compiling from Linux, rebuilds may be as much as 20x slower than they should be! Disk access during linking seems to be the bottleneck. It's recommended to move your folder to the Linux filesystem.

Use LLD for the linker

Using lld for Rust's linker makes build times a lot faster, and I highly recommend it.

Create ~/.cargo/config.toml if it does not exist and add this to it:

[build]
# Link with lld, per https://github.com/rust-lang/rust/issues/39915#issuecomment-538049306
# Use target-cpu=native, per https://deterministic.space/high-performance-rust.html
rustflags = ["-C", "link-arg=-fuse-ld=lld", "-C", "target-cpu=native"]

Then install lld version 13 (e.g. with $ sudo apt-get install lld-13) and add make sure there's a ld.lld executable on your PATH which is symlinked to lld-13.

That's it! Enjoy the faster builds.