feat: make it easy to add paths in workspace

Author: Pacman99

nix/public-flake-module.nix

@@ -23,12 +23,19 @@ ourArgs:
           cfg = config.crate2nix;
 
           crate2nix = ourArgs.self.packages.${pkgs.system}.default;
+
+          customBuildAttrs = [
+            "pkgs" "rust" "cargo" "target" "profile"
+            "targetFeatures" "globalRustcOpts" "includePaths"
+          ];
+
 
           cargoModule = { config, ... }:
           let
+            cargoRoot = builtins.dirOf config.cargoNix.path;
             importCargoNix =
               {
-                pkgs ? perSystem.pkgs
+                pkgs ? config.pkgs
               , rust ? config.toolchain.rust
               , cargo ? config.toolchain.cargo
               , target ? null
@@ -41,9 +48,34 @@ ourArgs:
               let
                 # Remove target from final crate overrides
                 # If target is an attrset, mkDerivation tries to coerce it to a string
+                fixOverride = override: attrs:
+                  let
+                    overrideAttrs = override attrs;
+                    origSrc = attrs.src.origSrc or cargoRoot;
+                    src = if overrideAttrs ? includePaths
+                      then lib.cleanSourceWith {
+                        filter = cfg.cargoNix.internal.sourceFilter;
+                        src = lib.fileset.toSource {
+                          root = cargoRoot;
+                          fileset = lib.fileset.unions ([
+                            origSrc
+                          ] ++ overrideAttrs.includePaths);
+                        };
+                      }
+                      else overrideAttrs.src or attrs.src or cargoRoot;
+                    cratePath = lib.path.removePrefix cargoRoot origSrc;
+                  in
+                    (lib.removeAttrs overrideAttrs customBuildAttrs) // ({
+                      inherit src;
+                      # automatically perform a deep merge on meta attributes in override
+                      meta = (attrs.meta or {}) // (overrideAttrs.meta or {});
+                    } // (lib.optionalAttrs (overrideAttrs ? includePaths) {
+                      sourceRoot = overrideAttrs.sourceRoot or "${src.name}/${cratePath}";
+                    }));
+
                 cleanedCrateOverrides =
                   lib.mapAttrs
-                    (_: override: attrs: lib.removeAttrs (override attrs) [ "target" "globalRustcOpts"])
+                    (_: fixOverride)
                     config.crateOverrides;
 
                 finalPkgs =
@@ -80,13 +112,9 @@ ourArgs:
                 };
                 overrideAttrNames = builtins.attrNames crateOverrides;
                 isInOverride = n: lib.elem n overrideAttrNames;
-                globalBuildAttrs = [
-                  "pkgs" "rust" "cargo" "target" "profile"
-                  "targetFeatures" "globalRustcOpts"
-                ];
                 build = (importCargoNix importArgs).workspaceMembers.${name}.build;
               in
-              if lib.any isInOverride globalBuildAttrs
+              if lib.any isInOverride customBuildAttrs
               then member // { inherit build; }
               else member;
 
@@ -204,6 +232,12 @@ ourArgs:
                   Used for conditional compilation based on CPU feature detection.
                 '';
               };
+              pkgs = lib.mkOption {
+                type = types.unspecified;
+                description = "Package set to use for Cargo.nix.";
+                default = pkgs;
+                defaultText = lib.literalExpression "pkgs (module argument)";
+              };
               packages = lib.mkOption {
                 type = types.attrsOf types.package;
                 readOnly = true;