Support unused dependencies

lib.nix

@@ -99,7 +99,14 @@ rec
       } // (lib.optionalAttrs (! isNull branch) { inherit branch; })
         // (lib.optionalAttrs (! isNull tag) { inherit tag; })
         // (lib.optionalAttrs (! isNull rev) { inherit rev; });
-      packageLocks = builtins.map parseLock (lib.filter query cargolock.package);
+
+      usedPackageLocks =
+        builtins.map parseLock (lib.filter query cargolock.package);
+
+      unusedPackageLocks =
+        builtins.map parseLock (lib.filter query ((cargolock.patch or []).unused or []));
+
+      packageLocks = usedPackageLocks ++ unusedPackageLocks;
 
       mkFetch = lock: {
         key = lock.rev or lock.tag or lock.branch or lock.revision

test/fast/default.nix

@@ -16,6 +16,7 @@ args: {
   simple-dep = import ./simple-dep args;
   simple-dep-patched = import ./simple-dep-patched args;
   symlinks = import ./symlinks args;
+  unused-patch = import ./unused-patch args;
   workspace = import ./workspace args;
   workspace-build-rs = import ./workspace-build-rs args;
   workspace-patched = import ./workspace-patched args;

test/fast/unused-patch/default.nix

@@ -0,0 +1,15 @@
+{ naersk, pkgs, ... }:
+let
+  app = naersk.buildPackage {
+    src = ./fixtures;
+  };
+
+in
+if builtins.compareVersions pkgs.lib.version "22.11" <= 0 then
+  # Executing this test requires nixpkgs > 22.11 due to changes to the TOML
+  # serialization function.
+  #
+  # See `writeTOML` in this repository for more details.
+  true
+else
+  app

test/fast/unused-patch/fixtures/Cargo.toml

@@ -0,0 +1,7 @@
+[package]
+name = "app"
+version = "0.1.0"
+edition = "2018"
+
+[patch.crates-io]
+uuid = { git = "https://github.com/uuid-rs/uuid" }

test/fast/unused-patch/fixtures/src/main.rs

@@ -0,0 +1,3 @@
+fn main() {
+    println!("Hello, world!");
+}