rust: replace fenix with rust-overlay allow specifying rust version

docs/reference/options.md

@@ -9213,8 +9213,6 @@ list of package
 
 ## git-hooks.hooks.dune-fmt.stages
 
-
-
 Confines the hook to run at a particular stage.
 
 
@@ -11311,8 +11309,6 @@ null or signed integer
 
 ## git-hooks.hooks.flynt.settings.no-multiline
 
-
-
 Convert only single line expressions.
 
 
@@ -13442,8 +13438,6 @@ list of string
 
 ## git-hooks.hooks.isort.description
 
-
-
 Description of the hook. Used for metadata purposes only.
 
 
@@ -15482,8 +15476,6 @@ internal name, same as ` id `
 
 ## git-hooks.hooks.lychee.pass_filenames
 
-
-
 Whether to pass filenames as arguments to the entry point.
 
 
@@ -17591,8 +17583,6 @@ list of package
 
 ## git-hooks.hooks.mypy.fail_fast
 
-
-
 if true pre-commit will stop running hooks if this hook fails.
 
 
@@ -19682,8 +19672,6 @@ list of (one of “commit-msg”, “post-checkout”, “post-commit”, “pos
 
 ## git-hooks.hooks.ormolu.types
 
-
-
 List of file types to run on. See [Filtering files with types](https://pre-commit.com/\#filtering-files-with-types).
 
 
@@ -21801,8 +21789,6 @@ list of package
 
 ## git-hooks.hooks.prettier.fail_fast
 
-
-
 if true pre-commit will stop running hooks if this hook fails.
 
 
@@ -23826,8 +23812,6 @@ submodule
 
 ## git-hooks.hooks.pyright.enable
 
-
-
 Whether to enable this pre-commit hook.
 
 
@@ -34947,7 +34931,7 @@ string
 
 
 
-List of extra [targets](https://github.com/nix-community/fenix\#supported-platforms-and-targets)
+List of extra [targets](https://doc.rust-lang.org/nightly/rustc/platform-support.html)
 to install. Defaults to only the native target.
 
 
@@ -35091,6 +35075,28 @@ null or package
 
 
 
+## languages.rust.version
+
+
+
+Which version of rust to use, this value could be ` latest `,` 1.81.0 `, ` 2021-01-01 `.
+Only works when languages.rust.channel is NOT nixpkgs.
+
+
+
+*Type:*
+string
+
+
+
+*Default:*
+` "latest" `
+
+*Declared by:*
+ - [https://github.com/cachix/devenv/blob/main/src/modules/languages/rust.nix](https://github.com/cachix/devenv/blob/main/src/modules/languages/rust.nix)
+
+
+
 ## languages.scala.enable
 
 

docs/supported-languages/rust.md

@@ -103,7 +103,7 @@ string
 
 
 
-List of extra [targets](https://github\.com/nix-community/fenix\#supported-platforms-and-targets)
+List of extra [targets](https://doc\.rust-lang\.org/nightly/rustc/platform-support\.html)
 to install\. Defaults to only the native target\.
 
 
@@ -223,3 +223,22 @@ null or package
 
 *Default:*
 ` pkgs.rustfmt `
+
+
+
+## languages\.rust\.version
+
+
+
+Which version of rust to use, this value could be ` latest `,` 1.81.0 `, ` 2021-01-01 `\.
+Only works when languages\.rust\.channel is NOT nixpkgs\.
+
+
+
+*Type:*
+string
+
+
+
+*Default:*
+` "latest" `

examples/rust-wasm-cross/devenv.yaml

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

examples/rust/devenv.yaml

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

src/modules/languages/rust.nix

@@ -3,16 +3,44 @@
 let
   cfg = config.languages.rust;
 
-  fenix = config.lib.getInput {
-    name = "fenix";
-    url = "github:nix-community/fenix";
-    attribute = "languages.rust.version";
+  rust-overlay = config.lib.getInput {
+    name = "rust-overlay";
+    url = "github:oxalica/rust-overlay";
+    attribute = "languages.rust.input";
     follows = [ "nixpkgs" ];
   };
+
+  # https://github.com/nix-community/fenix/blob/cdfd7bf3e3edaf9e3f6d1e397d3ee601e513613c/lib/combine.nix
+  combine = name: paths:
+    pkgs.symlinkJoin {
+      inherit name paths;
+      postBuild = ''
+        for file in $(find $out/bin -xtype f -maxdepth 1); do
+          install -m755 $(realpath "$file") $out/bin
+
+          if [[ $file =~ /rustfmt$ ]]; then
+            continue
+          fi
+
+          ${lib.optionalString pkgs.stdenv.isLinux ''
+            if isELF "$file"; then
+              patchelf --set-rpath $out/lib "$file" || true
+            fi
+          ''}
+
+          ${lib.optionalString pkgs.stdenv.isDarwin ''
+            install_name_tool -add_rpath $out/lib "$file" || true
+          ''}
+        done
+
+        for file in $(find $out/lib -name "librustc_driver-*"); do
+          install $(realpath "$file") "$file"
+        done
+      '';
+    };
 in
 {
   imports = [
-    (lib.mkRenamedOptionModule [ "languages" "rust" "version" ] [ "languages" "rust" "channel" ])
     (lib.mkRenamedOptionModule [ "languages" "rust" "packages" ] [ "languages" "rust" "toolchain" ])
   ];
 
@@ -34,8 +62,8 @@ in
       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.
+        List of extra [targets](https://doc.rust-lang.org/nightly/rustc/platform-support.html)
+        to install. Defaults to only the native target. 
       '';
     };
 
@@ -46,6 +74,16 @@ in
       description = "The rustup toolchain to install.";
     };
 
+    version = lib.mkOption {
+      type = lib.types.str;
+      default = "latest";
+      defaultText = lib.literalExpression ''"latest"'';
+      description = ''
+        Which version of rust to use, this value could be `latest`,`1.81.0`, `2021-01-01`.
+        Only works when languages.rust.channel is NOT nixpkgs.
+      '';
+    };
+
     rustflags = lib.mkOption {
       type = lib.types.str;
       default = "";
@@ -101,6 +139,17 @@ in
               The nixpkgs channel does not support cross-compiling with targets.
               Use the stable, beta, or nightly channels instead. For example:
 
+              languages.rust.channel = "stable";
+            '';
+          }
+          {
+            assertion = cfg.channel == "nixpkgs" -> (cfg.version == "latest");
+            message = ''
+              Cannot use `languages.rust.channel = "nixpkgs"` with `languages.rust.version`.
+
+              The nixpkgs channel does not contain all versions required, and is
+              therefore not supported to be used together.
+
               languages.rust.channel = "stable";
             '';
           }
@@ -154,21 +203,17 @@ in
 
     (lib.mkIf (cfg.channel != "nixpkgs") (
       let
-        rustPackages = fenix.packages.${pkgs.stdenv.system};
-        fenixChannel =
-          if cfg.channel == "nightly"
-          then "latest"
-          else cfg.channel;
-        toolchain = rustPackages.${fenixChannel};
+        toolchain = (rust-overlay.lib.mkRustBin { } pkgs.buildPackages)."${cfg.channel}"."${cfg.version}";
+        filteredToolchain = (lib.filterAttrs (n: _: builtins.elem n toolchain._manifest.profiles.complete) toolchain);
       in
       {
         languages.rust.toolchain =
-          (builtins.mapAttrs (_: pkgs.lib.mkDefault) toolchain);
+          (builtins.mapAttrs (_: pkgs.lib.mkDefault) filteredToolchain);
 
         packages = [
-          (rustPackages.combine (
-            (map (c: toolchain.${c}) cfg.components) ++
-            (map (t: rustPackages.targets.${t}.${fenixChannel}.rust-std) cfg.targets)
+          (combine "rust-mixed" (
+            (map (c: cfg.toolchain.${c}) (cfg.components ++ [ "rust-std" ])) ++
+            (map (t: toolchain._components.${t}.rust-std) cfg.targets)
           ))
         ];
       }

tests/rust/devenv.nix

@@ -2,9 +2,9 @@
   languages.rust.enable = true;
   languages.rust.mold.enable = false;
   enterTest = ''
-    if [ -n "$RUSTFLAGS" ]; then
-      echo "RUSTFLAGS is set, but it should not be"
-      exit 1
+    if [ -n "''${RUSTFLAGS:-}" ]; then
+        echo "RUSTFLAGS is set, but it should not be"
+        exit 1
     fi
   '';
 }