Add rust targets

examples/rust-wasm-cross/.test.js

@@ -0,0 +1 @@
+import("./app/pkg/app.js").then((app) => app.main());

examples/rust-wasm-cross/.test.sh

@@ -0,0 +1,17 @@
+#!/usr/bin/env bash
+set -ex
+cargo --version
+rustc --version
+
+if [[ "$(uname)" == "Darwin" ]]; then
+  echo "$RUSTFLAGS" | grep -- "-L framework=$DEVENV_PROFILE/Library/Frameworks"
+  echo "$RUSTDOCFLAGS" | grep -- "-L framework=$DEVENV_PROFILE/Library/Frameworks"
+  echo "$CFLAGS" | grep -- "-iframework $DEVENV_PROFILE/Library/Frameworks"
+fi
+
+[[ "$CARGO_INSTALL_ROOT" == "$DEVENV_STATE/cargo-install" ]]
+echo "$PATH" | grep -- "$CARGO_INSTALL_ROOT/bin"
+
+wasm-pack build ./app --target nodejs
+
+node .test.js

examples/rust-wasm-cross/app/Cargo.toml

@@ -0,0 +1,18 @@
+[lib]
+crate-type = ["cdylib", "rlib"]
+
+[package]
+name = "app"
+version = "0.1.0"
+edition = "2021"
+
+# See more keys and their definitions at https://doc.rust-lang.org/cargo/reference/manifest.html
+
+[dependencies]
+wasm-bindgen = "0.2.84"
+
+[profile.release]
+# Tell `rustc` to optimize for small code size.
+opt-level = "s"
+
+[workspace]

examples/rust-wasm-cross/app/src/lib.rs

@@ -0,0 +1,36 @@
+use wasm_bindgen::prelude::*;
+
+// First up let's take a look of binding `console.log` manually, without the
+// help of `web_sys`. Here we're writing the `#[wasm_bindgen]` annotations
+// manually ourselves, and the correctness of our program relies on the
+// correctness of these annotations!
+
+#[wasm_bindgen]
+extern "C" {
+    // Use `js_namespace` here to bind `console.log(..)` instead of just
+    // `log(..)`
+    #[wasm_bindgen(js_namespace = console)]
+    fn log(s: &str);
+
+    // The `console.log` is quite polymorphic, so we can bind it with multiple
+    // signatures. Note that we need to use `js_name` to ensure we always call
+    // `log` in JS.
+    #[wasm_bindgen(js_namespace = console, js_name = log)]
+    fn log_u32(a: u32);
+
+    // Multiple arguments too!
+    #[wasm_bindgen(js_namespace = console, js_name = log)]
+    fn log_many(a: &str, b: &str);
+}
+
+macro_rules! console_log {
+    // Note that this is using the `log` function imported above during
+    // `bare_bones`
+    ($($t:tt)*) => (log(&format_args!($($t)*).to_string()))
+}
+
+// Called by our JS entry point to run the example.
+#[wasm_bindgen]
+pub fn main() {
+    console_log!("Hello, from devenv!");
+}

examples/rust-wasm-cross/devenv.nix

@@ -0,0 +1,26 @@
+{ pkgs, lib, ... }:
+
+{
+  languages.rust = {
+    enable = true;
+    # https://devenv.sh/reference/options/#languagesrustchannel
+    channel = "nightly";
+
+    targets = [ "wasm32-unknown-unknown" ];
+
+    components = [ "rustc" "cargo" "clippy" "rustfmt" "rust-analyzer" "rust-std" ];
+  };
+
+  # These break us
+  # pre-commit.hooks = {
+  #  rustfmt.enable = true;
+  #  clippy.enable = true;
+  # };
+
+  packages = [
+    pkgs.wasm-pack
+    pkgs.nodejs
+  ] ++ lib.optionals pkgs.stdenv.isDarwin (with pkgs.darwin.apple_sdk; [
+    frameworks.Security
+  ]);
+}

examples/rust-wasm-cross/devenv.yaml

@@ -0,0 +1,6 @@
+inputs:
+  fenix:
+    url: github:nix-community/fenix
+    inputs:
+      nixpkgs:
+        follows: nixpkgs

src/modules/languages/rust.nix

@@ -29,6 +29,16 @@ in
       '';
     };
 
+    targets = lib.mkOption {
+      type = lib.types.listOf lib.types.str;
+      default = [ ];
+      defaultText = lib.literalExpression ''[ ]'';
+      description = ''
+        List of extra [targets](https://github.com/nix-community/fenix#supported-platforms-and-targets)
+        to install. Defaults to only the native target. 
+      '';
+    };
+
     channel = lib.mkOption {
       type = lib.types.enum [ "nixpkgs" "stable" "beta" "nightly" ];
       default = "nixpkgs";
@@ -76,7 +86,10 @@ in
           export PATH="$PATH:$CARGO_INSTALL_ROOT/bin"
         '';
 
-        packages = (builtins.map (c: cfg.toolchain.${c} or (throw "toolchain.${c}")) cfg.components)
+        packages =
+          # If there are targets we want to add the whole toolchain instead
+          # TODO: It might always be fine to add the whole toolchain when not using `nixpkgs`
+          lib.optionals (cfg.targets == [ ]) (builtins.map (c: cfg.toolchain.${c} or (throw "toolchain.${c}")) cfg.components)
           ++ lib.optional pkgs.stdenv.isDarwin pkgs.libiconv;
 
         # enable compiler tooling by default to expose things like cc
@@ -108,10 +121,33 @@ in
           let
             toolchain =
               if cfg.channel == "nightly"
-              then rustPackages.latest
-              else rustPackages.${cfg.channel};
+              then
+                rustPackages.latest
+              else
+                rustPackages.${cfg.channel}
+            ;
           in
           (builtins.mapAttrs (_: pkgs.lib.mkDefault) toolchain);
+
+        packages = [
+          (rustPackages.combine
+            (
+              (map (c: config.languages.rust.toolchain.${c}) cfg.components) ++
+              (map
+                (t:
+                  let
+                    target_toolchain =
+                      if cfg.channel == "nightly"
+                      then
+                        rustPackages.targets.${t}.latest
+                      else
+                        rustPackages.targets.${t}.${cfg.channel}
+                    ;
+                  in
+                  target_toolchain.rust-std)
+                cfg.targets)
+            ))
+        ];
       }
     ))
   ];