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Add a Nix configuration for the cargo rust-gpu environment #3027

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8507d6d
Try providing cargo-rust-gpu to nix devs
timon-schelling Aug 7, 2025
202a44d
Try providing cargo-rust-gpu to nix devs
timon-schelling Aug 7, 2025
75bbe25
Add exec with rust-gpu env script to flake
timon-schelling Aug 8, 2025
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50 changes: 46 additions & 4 deletions .nix/flake.nix
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Original file line number Diff line number Diff line change
Expand Up @@ -34,11 +34,52 @@
inherit system overlays;
};

rustc-wasm = pkgs.rust-bin.stable.latest.default.override {
rustExtensions = [ "rust-src" "rust-analyzer" "clippy" "cargo" ];
rust = pkgs.rust-bin.stable.latest.default.override {
targets = [ "wasm32-unknown-unknown" ];
extensions = [ "rust-src" "rust-analyzer" "clippy" "cargo" ];
extensions = rustExtensions;
};

rustGPUToolchainPkg = pkgs.rust-bin.nightly."2025-06-23".default.override {
extensions = rustExtensions ++ [ "rustc-dev" "llvm-tools" ];
};
rustGPUToolchainRustPlatform = pkgs.makeRustPlatform {
cargo = rustGPUToolchainPkg;
rustc = rustGPUToolchainPkg;
};
rustc_codegen_spirv = rustGPUToolchainRustPlatform.buildRustPackage (finalAttrs: {
pname = "rustc_codegen_spirv";
version = "0-unstable-2025-08-04";
src = pkgs.fetchFromGitHub {
owner = "Rust-GPU";
repo = "rust-gpu";
rev = "df1628a032d22c864397417c2871b74d602af986";
hash = "sha256-AFt3Nc+NqK8DxNUhDBcOUmk3XDVcoToVeFIMYNszdbY=";
};
cargoHash = "sha256-en3BYJWQabH064xeAwYQrvcr6EuWg/QjvsG+Jd6HHCk";
cargoBuildFlags = [ "-p" "rustc_codegen_spirv" "--features=use-installed-tools" "--no-default-features" ];
doCheck = false;
});

# Wrapper script for running rust commands with the rust toolchain used by rust-gpu.
# For example `rust-gpu cargo --version` or `rust-gpu rustc --version`.
execWithRustGPUEnvironment = pkgs.writeShellScriptBin "rust-gpu" ''
#!${pkgs.lib.getExe pkgs.bash}

filtered_args=()
for arg in "$@"; do
case "$arg" in
+nightly|+nightly-*) ;;
*) filtered_args+=("$arg") ;;
esac
done

export PATH="${pkgs.lib.makeBinPath [ rustGPUToolchainPkg pkgs.spirv-tools ]}:$PATH"
export RUSTC_CODEGEN_SPIRV_PATH="${rustc_codegen_spirv}/lib/librustc_codegen_spirv.so"

exec ${"\${filtered_args[@]}"}
'';
Comment on lines +66 to +81
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It's so much easier to use RUSTUP_TOOLCHAIN for this, I was just asking @Firestar99 why the + syntax when the env var also works.

All you need in the script, if you want to have dynamic dispatch, is:

''
  #!${pkgs.lib.getExe pkgs.bash}
  exec "${toolchains}/${"\$"}{RUSTUP_TOOLCHAIN:-stable}/bin/$(basename "$0")" "$@"
''

(I don't like that ${"\$"} but am not sure I can make it much nicer)

I suppose something different than what you are doing today is you would want to define toolchains as one of those sym trees with one directory per supported toolchain - maybe the oxalica overlay rust-bin has something along those lines? (it's been a while since I looked at it anyway)

Although, if cargo-gpu/spirv-builder switched to setting RUSTUP_TOOLCHAIN, the fact that this script only has to filter out the + syntax, makes me think the script can just go away? (since I guess there is no dynamic dispatch right now, just a pesky first argument)

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We don't want devs mistaking the pinned rust-gpu rust nightly toolchain for a normal nightly toolchain. We want a way to ensure that it is only ever usable to compile rust-gpu code. A wrapper script is the best way to ensure that in my opinion.

But getting rid of the filter logic would be great. Thanks for the comment.

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@Firestar99 Firestar99 Aug 20, 2025 •
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I just want to note that on master, we kill the RUSTUP_TOOLCHAIN env var. I'm unsure if my branch has these changes already or not, so we could see behaviour differences between now and me rebasing the branch.

https://github.com/Rust-GPU/rust-gpu/blob/e0dfdd1112d9b2cf27d10e25104dc997db9acdf0/crates/spirv-builder/src/cargo_cmd.rs#L52

Yes we do need a better solution for this, but since this has to work within the next week, it'll have to wait.


libcef = pkgs.libcef.overrideAttrs (finalAttrs: previousAttrs: {
version = "139.0.17";
gitRevision = "6c347eb";
Expand All @@ -51,7 +92,6 @@
strip $out/lib/*
'';
});

libcefPath = pkgs.runCommand "libcef-path" {} ''
mkdir -p $out

Expand Down Expand Up @@ -85,7 +125,7 @@

# Development tools that don't need to be in LD_LIBRARY_PATH
buildTools = [
rustc-wasm
rust
pkgs.nodejs
pkgs.nodePackages.npm
pkgs.binaryen
Expand All @@ -97,6 +137,8 @@

# Linker
pkgs.mold

execWithRustGPUEnvironment
];
# Development tools that don't need to be in LD_LIBRARY_PATH
devTools = with pkgs; [
Expand Down
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