feat: add defaultOverride option

Author: Pacman99

nix/public-flake-module.nix

@@ -103,14 +103,16 @@ ourArgs:
             # Handle possible cross compiling requests in crateOverrides
             fixCrossMemberBuild = path: name: member:
               let
-                crateOverrides =
-                  if config.crateOverrides ? ${name}
-                  then config.crateOverrides.${name} {}
-                  else {};
+                defaultOverride = config.defaultOverride {};
+                crateOverrides = defaultOverride //
+                  (if config.crateOverrides ? ${name}
+                  then (config.crateOverrides.${name} {})
+                  else {});
                 importArgs = crateOverrides // {
                   inherit path;
                 };
-                overrideAttrNames = builtins.attrNames crateOverrides;
+                overrideAttrNames = builtins.attrNames
+                  (defaultOverride // crateOverrides);
                 isInOverride = n: lib.elem n overrideAttrNames;
                 build = (importCargoNix importArgs).workspaceMembers.${name}.build;
               in
@@ -137,6 +139,16 @@ ourArgs:
                     in builtins.map (m: m.build) members;
                 };
               };
+
+            overrideType = types.submodule {
+              freeformType = types.attrsOf types.anything;
+              options = {
+                meta = lib.mkOption {
+                  type = types.attrsOf types.anything;
+                  default = {};
+                };
+              };
+            };
           in
           {
             options = {
@@ -209,8 +221,15 @@ ourArgs:
                   '';
                 };
               };
+              defaultOverride = lib.mkOption {
+                type = types.functionTo overrideType;
+                default = _: {};
+                description = ''
+                  Default overrides for all workspace members.
+                '';
+              };
               crateOverrides = lib.mkOption {
-                type = types.attrsOf (types.anything);
+                type = types.attrsOf (types.functionTo overrideType);
                 default = {};
                 description = ''
                   Crate overrides.
@@ -266,7 +285,10 @@ ourArgs:
                 lib.mapAttrs (_: lib.getAttr "build") config.cargoNix.workspaceMembers;
               checks =
                 lib.mapAttrs (_: m: m.build.override { runTests = true; }) config.cargoNix.workspaceMembers;
-              crateOverrides = ourArgs.self.tools.${pkgs.system}.crateOverrides;
+              crateOverrides = lib.mkMerge [
+                ourArgs.self.tools.${pkgs.system}.crateOverrides
+                (lib.mapAttrs (_: _: config.defaultOverride) config.cargoNix.workspaceMembers)
+              ];
             };
           };