feat(corp/tvixbolt): add Nix build instructions r/4791

Now that tvix-eval has almost caught up, tvixbolt can be built in
the depot tree.

Change-Id: Ib26dd98727b110ad8d668aec60db99678644a167
Reviewed-on: https://cl.tvl.fyi/c/depot/+/6491
Tested-by: BuildkiteCI
Autosubmit: tazjin <tazjin@tvl.su>
Reviewed-by: sterni <sternenseemann@systemli.org>

2 files changed, 80 insertions, 1 deletions

diff --git a/corp/tvixbolt/Cargo.toml b/corp/tvixbolt/Cargo.toml
index 5b5e955efcda..2e6c7932096f 100644
--- a/corp/tvixbolt/Cargo.toml
+++ b/corp/tvixbolt/Cargo.toml
@@ -10,10 +10,13 @@ yew = "0.19.3"
 codemap = "0.1.3"
 web-sys = "*"
 
+# needs to be in sync with nixpkgs
+wasm-bindgen = "= 0.2.82"
+
 [dependencies.rnix]
 git = "https://github.com/nix-community/rnix-parser.git"
 rev = "97b438e34be5211a4b48aeed9cc3ded489b4d6da"
 
 [dependencies.tvix-eval]
-path = "../tvix-eval/tvix/eval"
+path = "../../tvix/eval"
 default-features = false
diff --git a/corp/tvixbolt/default.nix b/corp/tvixbolt/default.nix
new file mode 100644
index 000000000000..a55b249b5f26
--- /dev/null
+++ b/corp/tvixbolt/default.nix
@@ -0,0 +1,76 @@
+{ depot, lib, pkgs, ... }:
+
+let
+  wasmRust = pkgs.rust-bin.stable.latest.default.override {
+    targets = [ "wasm32-unknown-unknown" ];
+  };
+
+  cargoToml = with builtins; fromTOML (readFile ./Cargo.toml);
+
+  wasmBindgenMatch =
+    cargoToml.dependencies.wasm-bindgen == "= ${pkgs.wasm-bindgen-cli.version}";
+
+  assertWasmBindgen = assert (lib.assertMsg wasmBindgenMatch ''
+    Due to instability in the Rust WASM ecosystem, the trunk build
+    tool enforces that the Cargo-dependency version of `wasm-bindgen`
+    MUST match the version of the CLI supplied in the environment.
+
+    This can get out of sync when nixpkgs is updated. To resolve it,
+    wasm-bindgen must be bumped in the Cargo.toml file and cargo needs
+    to be run to resolve the dependencies.
+
+    Versions of `wasm-bindgen` in Cargo.toml:
+
+      Expected: '= ${pkgs.wasm-bindgen-cli.version}'
+      Actual:   '${cargoToml.dependencies.wasm-bindgen}'
+  ''); pkgs.wasm-bindgen-cli;
+
+  deps = [
+    pkgs.binaryen
+    pkgs.sass
+    pkgs.trunk
+
+    wasmRust
+    assertWasmBindgen
+  ];
+
+  # Cargo.toml needs to be patched with the /nix/store source path of
+  # tvix-eval.
+  cargoTomlPatch = pkgs.writeText "tvix-eval-src.patch" ''
+    diff --git a/Cargo.toml b/Cargo.toml
+    index 2e6c793..67280e7 100644
+    --- a/Cargo.toml
+    +++ b/Cargo.toml
+    @@ -18,5 +18,5 @@ git = "https://github.com/nix-community/rnix-parser.git"
+     rev = "97b438e34be5211a4b48aeed9cc3ded489b4d6da"
+
+     [dependencies.tvix-eval]
+    -path = "../../tvix/eval"
+    +path = "${depot.tvix.eval.src}"
+     default-features = false
+  '';
+
+in
+pkgs.rustPlatform.buildRustPackage rec {
+  pname = "tvixbolt";
+  version = "canon";
+  src = lib.cleanSource ./.;
+
+  cargoLock.lockFile = ./Cargo.lock;
+  cargoLock.outputHashes = {
+    "rnix-0.11.0-dev" = "sha256:1dd8gf2v4v6451r3n9iaks7bqk55izgblkqzymx77advpqwlpymq";
+  };
+
+  patches = [
+    cargoTomlPatch
+  ];
+
+  buildPhase = ''
+    export PATH=${lib.makeBinPath deps}:$PATH
+    mkdir home
+    export HOME=$PWD/home
+    trunk build --release -d $out
+  '';
+
+  dontInstall = true;
+}