migrate .resi files as well

Author: zth

tests/tools_tests/src/expected/StdlibMigration_Interface.res.expected

@@ -0,0 +1,9 @@
+/* Implementation to satisfy interface build for tests */
+
+external arr: array<int> = "arr"
+external reT: RegExp.t = "re"
+external json: JSON.t = "json"
+external nestedArr: array<RegExp.t> = "nestedArr"
+
+external useSet: Set.t<int> => unit = "useSet"
+

tests/tools_tests/src/expected/StdlibMigration_Interface.resi.expected

@@ -0,0 +1,11 @@
+/* Migration tests for interface (.resi) files using stdlib deprecations */
+
+// Type alias migrations exercised via externals
+external arr: JSON.t<int> = "arr"
+external reT: Js.Re.t = "re"
+external json: Js.Json.t = "json"
+external nestedArr: Js.Array.t<Js.Re.t> = "nestedArr"
+
+// Function type using a deprecated alias
+external useSet: Js.Set.t<int> => unit = "useSet"
+

tests/tools_tests/src/migrate/StdlibMigration_Interface.res

@@ -0,0 +1,8 @@
+/* Implementation to satisfy interface build for tests */
+
+external arr: Js.Array.t<int> = "arr"
+external reT: Js.Re.t = "re"
+external json: Js.Json.t = "json"
+external nestedArr: Js.Array.t<Js.Re.t> = "nestedArr"
+
+external useSet: Js.Set.t<int> => unit = "useSet"

tests/tools_tests/src/migrate/StdlibMigration_Interface.resi

@@ -0,0 +1,10 @@
+/* Migration tests for interface (.resi) files using stdlib deprecations */
+
+// Type alias migrations exercised via externals
+external arr: Js.Array.t<int> = "arr"
+external reT: Js.Re.t = "re"
+external json: Js.Json.t = "json"
+external nestedArr: Js.Array.t<Js.Re.t> = "nestedArr"
+
+// Function type using a deprecated alias
+external useSet: Js.Set.t<int> => unit = "useSet"

tests/tools_tests/src/migrate/migrated/Migrated_StdlibMigration_Interface.res

@@ -0,0 +1,10 @@
+// This file is autogenerated so it can be type checked.
+// It's the migrated version of src/migrate/StdlibMigration_Interface.res.
+/* Implementation to satisfy interface build for tests */
+
+external arr: array<int> = "arr"
+external reT: RegExp.t = "re"
+external json: JSON.t = "json"
+external nestedArr: array<RegExp.t> = "nestedArr"
+
+external useSet: Set.t<int> => unit = "useSet"

tools/src/migrate.ml

@@ -703,9 +703,29 @@ let migrate ~entryPointFile ~outputMode =
       let {Res_driver.parsetree = signature; comments; source} =
         parser ~filename:path
       in
-      let mapper = makeMapper [] in
-      let astMapped = mapper.signature mapper signature in
-      Ok (Res_printer.print_interface astMapped ~comments, source)
+      (* Load cmti/cmt info to obtain deprecation migration templates, just like .res *)
+      match
+        (* Prefer implementation cmt info when available, since cmti may not
+            record deprecated usages. Fallback to cmti if needed. *)
+        let impl_path =
+          if Filename.check_suffix path ".resi" then
+            Filename.chop_suffix path ".resi" ^ ".res"
+          else path
+        in
+        match Cmt.loadCmtInfosFromPath ~path:impl_path with
+        | Some infos -> Some infos
+        | None -> Cmt.loadCmtInfosFromPath ~path
+      with
+      | None ->
+        Error
+          (Printf.sprintf
+             "error: failed to run migration for %s because build artifacts \
+              could not be found. try to build the project"
+             path)
+      | Some {cmt_extra_info = {deprecated_used}} ->
+        let mapper = makeMapper deprecated_used in
+        let astMapped = mapper.signature mapper signature in
+        Ok (Res_printer.print_interface astMapped ~comments, source)
     else
       Error
         (Printf.sprintf