1 files changed, 77 insertions, 0 deletions
diff --git a/pkgs/rust/lib/crate2nix-package.nix b/pkgs/rust/lib/crate2nix-package.nix
new file mode 100644
index 0000000..d97a97e
--- /dev/null
+++ b/pkgs/rust/lib/crate2nix-package.nix
@@ -0,0 +1,77 @@
+# Per-crate Rust builds with crate2nix.
+#
+# resolvedJson selects how the build plan is obtained:
+#   null (default)  <src>/Cargo.json if present, else IFD from <src>/Cargo.lock
+#   a path          that file (crate2nix generate --format json)
+#   false           always IFD from <src>/Cargo.lock
+#
+# Overrides are attrs, or functions from the crate's buildRustCrate arguments
+# to attrs, and are merged into those arguments before buildRustCrate sees
+# them, so they can also set release.  For a workspace member,
+# workspaceOverride applies first and crateOverrides.<name> sees its result.
+# nixpkgs' defaultCrateOverrides still apply inside buildRustCrate.
+
+{ pkgs
+, applyOverride
+
+, name
+, src
+
+# crate name -> attrs or (args -> attrs)
+, crateOverrides ? {}
+
+# attrs or (args -> attrs), for every workspace member
+, workspaceOverride ? {}
+
+# IFD only; Cargo.json has its features baked in
+, features ? [ "default" ]
+
+, resolvedJson ? null
+}:
+
+let
+  resolvedJsonFromSrc = src + "/Cargo.json";
+
+  useJson =
+    if resolvedJson == null then builtins.pathExists resolvedJsonFromSrc
+    else resolvedJson != false;
+
+  resolvedJson' =
+    if resolvedJson != null then resolvedJson else resolvedJsonFromSrc;
+
+  workspaceMembers = builtins.attrNames cargoNix.workspaceMembers;
+
+  buildRustCrateForPkgs = pkgs: args:
+    let
+      withWorkspace =
+        if builtins.elem args.crateName workspaceMembers
+        then applyOverride workspaceOverride args
+        else args;
+    in
+    pkgs.buildRustCrate
+      (applyOverride (crateOverrides.${args.crateName} or {}) withWorkspace);
+
+  fromJson = pkgs.crate2nix.build-from-json {
+    inherit buildRustCrateForPkgs pkgs src;
+    resolvedJson = resolvedJson';
+  };
+
+  fromLock =
+    pkgs.callPackage
+      (pkgs.crate2nix.tools.generatedCargoNix {
+        inherit name src;
+        additionalCargoNixArgs = [ "--all-features" ];
+      })
+      {
+        rootFeatures = features;
+        inherit buildRustCrateForPkgs;
+      };
+
+  cargoNix =
+    if useJson then fromJson else fromLock;
+in
+cargoNix // {
+  build =
+    if cargoNix.rootCrate or null != null then cargoNix.rootCrate.build
+    else cargoNix.allWorkspaceMembers;
+}