Add gentypeconfig.moduleResolution options: node16 and bundler for better interop with TS+ESM projects

CHANGELOG.md

@@ -15,6 +15,10 @@
 #### :rocket: Main New Feature
 
 - Add support for Dynamic import. https://github.com/rescript-lang/rescript-compiler/pull/5703
+- GenType: Add `moduleResolution` option to customize extensions on emitted import statements. This helps to adjust output compatibility with TypeScript projects using ESM. https://github.com/rescript-lang/rescript-compiler/pull/6182
+  - `node` (default): Drop extensions.
+  - `node16`: Use TS output's extensions. Make it ESM-compatible.
+  - `bundler`: Use TS input's extensions. Make it ESM-compatible.
 
 #### :boom: Breaking Change
 

jscomp/gentype/EmitType.ml

@@ -13,21 +13,6 @@ let fileHeader ~sourceFile =
     ~lines:["TypeScript file generated from " ^ sourceFile ^ " by genType."]
   ^ "/* eslint-disable import/first */\n\n"
 
-let generatedFilesExtension ~(config : Config.t) =
-  match config.generatedFileExtension with
-  | Some s ->
-    (* from .foo.bar to .foo *)
-    Filename.remove_extension s
-  | None -> ".gen"
-
-let outputFileSuffix ~(config : Config.t) =
-  match config.generatedFileExtension with
-  | Some s when Filename.extension s <> "" (* double extension  *) -> s
-  | _ -> generatedFilesExtension ~config ^ ".tsx"
-
-let generatedModuleExtension ~config = generatedFilesExtension ~config
-let shimExtension = ".shim.ts"
-
 let interfaceName ~(config : Config.t) name =
   match config.exportInterfaces with
   | true -> "I" ^ name
@@ -387,6 +372,13 @@ let emitRequire ~importedValueOrComponent ~early ~emitters ~(config : Config.t)
     | true -> "// tslint:disable-next-line:no-var-requires\n"
     | false -> "// @ts-ignore: Implicit any on import\n"
   in
+  let importPath =
+    match config.moduleResolution with
+    | Node ->
+      importPath
+      |> ImportPath.chopExtensionSafe (* for backward compatibility *)
+    | _ -> importPath
+  in
   match config.module_ with
   | ES6 when not importedValueOrComponent ->
     let moduleNameString = ModuleName.toString moduleName in

jscomp/gentype/GenTypeConfig.ml

@@ -1,6 +1,15 @@
 module ModuleNameMap = Map.Make (ModuleName)
 
 type module_ = CommonJS | ES6
+
+(** Compatibility for `compilerOptions.moduleResolution` in TypeScript projects. *)
+type moduleResolution =
+  | Node  (** should drop extension on import statements *)
+  | Node16
+      (** should use TS output's extension (e.g. `.gen.js`) on import statements *)
+  | Bundler
+      (** should use TS input's extension (e.g. `.gen.tsx`) on import statements *)
+
 type bsVersion = int * int * int
 
 type t = {
@@ -13,6 +22,7 @@ type t = {
   exportInterfaces: bool;
   generatedFileExtension: string option;
   module_: module_;
+  moduleResolution: moduleResolution;
   namespace: string option;
   platformLib: string;
   mutable projectRoot: string;
@@ -32,12 +42,13 @@ let default =
     exportInterfaces = false;
     generatedFileExtension = None;
     module_ = ES6;
+    moduleResolution = Node;
     namespace = None;
     platformLib = "";
     projectRoot = "";
     shimsMap = ModuleNameMap.empty;
     sources = None;
-    suffix = "";
+    suffix = ".bs.js";
   }
 
 let bsPlatformLib ~config =
@@ -112,6 +123,7 @@ let readConfig ~getBsConfigFile ~namespace =
   in
   let parseConfig ~bsconf ~gtconf =
     let moduleString = gtconf |> getStringOption "module" in
+    let moduleResolutionString = gtconf |> getStringOption "moduleResolution" in
     let exportInterfacesBool = gtconf |> getBool "exportInterfaces" in
     let generatedFileExtensionStringOption =
       gtconf |> getStringOption "generatedFileExtension"
@@ -143,6 +155,13 @@ let readConfig ~getBsConfigFile ~namespace =
       | None, Some ("es6" | "es6-global") -> ES6
       | _ -> default.module_
     in
+    let moduleResolution =
+      match moduleResolutionString with
+      | Some "node" -> Node
+      | Some "node16" -> Node16
+      | Some "bundler" -> Bundler
+      | _ -> default.moduleResolution
+    in
     let exportInterfaces =
       match exportInterfacesBool with
       | None -> default.exportInterfaces
@@ -171,9 +190,8 @@ let readConfig ~getBsConfigFile ~namespace =
     in
     let suffix =
       match bsconf |> getStringOption "suffix" with
-      | Some ".bs.js" -> ".bs"
       | Some s -> s
-      | _ -> ".bs"
+      | _ -> default.suffix
     in
     let bsDependencies =
       match bsconf |> getOpt "bs-dependencies" with
@@ -204,6 +222,7 @@ let readConfig ~getBsConfigFile ~namespace =
       exportInterfaces;
       generatedFileExtension;
       module_;
+      moduleResolution;
       namespace;
       platformLib;
       projectRoot;

jscomp/gentype/GenTypeMain.ml

@@ -103,8 +103,8 @@ let processCmtFile cmt =
     let fileName = cmt |> Paths.getModuleName in
     let isInterface = Filename.check_suffix cmtFile ".cmti" in
     let resolver =
-      ModuleResolver.createLazyResolver ~config
-        ~extensions:[".res"; EmitType.shimExtension] ~excludeFile:(fun fname ->
+      ModuleResolver.createLazyResolver ~config ~extensions:[".res"; ".shim.ts"]
+        ~excludeFile:(fun fname ->
           fname = "React.res" || fname = "ReasonReact.res")
     in
     let inputCMT, hasGenTypeAnnotations =

jscomp/gentype/ImportPath.ml

@@ -13,19 +13,17 @@ let fromModule ~dir ~importExtension moduleName =
 
 let fromStringUnsafe s = ("", s)
 
-let chopExtensionSafe s =
-  try s |> Filename.chop_extension with Invalid_argument _ -> s
+let chopExtensionSafe (dir, s) =
+  try (dir, s |> Filename.chop_extension) with Invalid_argument _ -> (dir, s)
 
 let dump (dir, s) = NodeFilename.concat dir s
 
 let toCmt ~(config : Config.t) ~outputFileRelative (dir, s) =
   let open Filename in
-  concat
-    (outputFileRelative |> dirname)
-    (((dir, s |> chopExtensionSafe) |> dump)
-    ^ (match config.namespace with
-      | None -> ""
-      | Some name -> "-" ^ name)
-    ^ ".cmt")
+  concat (outputFileRelative |> dirname) ((dir, s) |> chopExtensionSafe |> dump)
+  ^ (match config.namespace with
+    | None -> ""
+    | Some name -> "-" ^ name)
+  ^ ".cmt"
 
 let emit (dir, s) = (dir, s) |> dump

jscomp/gentype/ImportPath.mli

@@ -3,6 +3,7 @@ open GenTypeCommon
 type t
 
 val bsCurryPath : config:Config.t -> t
+val chopExtensionSafe : t -> t
 val dump : t -> string
 val emit : t -> string
 val fromModule : dir:string -> importExtension:string -> ModuleName.t -> t

jscomp/gentype/ModuleExtension.ml

@@ -0,0 +1,28 @@
+open GenTypeCommon
+
+let shimTsOutputFileExtension ~(config : Config.t) =
+  match config.moduleResolution with
+  | Node -> ".shim"
+  | Node16 -> ".shim.js"
+  | Bundler -> ".shim.ts"
+
+let generatedFilesExtension ~(config : Config.t) =
+  match config.generatedFileExtension with
+  | Some s ->
+    (* from .foo.bar to .foo *)
+    Filename.remove_extension s
+  | None -> ".gen"
+
+let tsInputFileSuffix ~(config : Config.t) =
+  match config.generatedFileExtension with
+  | Some s when Filename.extension s <> "" (* double extension  *) -> s
+  | _ -> generatedFilesExtension ~config ^ ".tsx"
+
+let tsOutputFileSuffix ~(config : Config.t) =
+  generatedFilesExtension ~config ^ ".js"
+
+let generatedModuleExtension ~(config : Config.t) =
+  match config.moduleResolution with
+  | Node -> generatedFilesExtension ~config
+  | Node16 -> tsOutputFileSuffix ~config
+  | Bundler -> tsInputFileSuffix ~config

jscomp/gentype/ModuleResolver.ml

@@ -256,7 +256,7 @@ let resolveGeneratedModule ~config ~outputFileRelative ~resolver moduleName =
       (moduleName |> ModuleName.toString);
   let importPath =
     resolveModule ~config
-      ~importExtension:(EmitType.generatedModuleExtension ~config)
+      ~importExtension:(ModuleExtension.generatedModuleExtension ~config)
       ~outputFileRelative ~resolver ~useBsDependencies:true moduleName
   in
   if !Debug.moduleResolution then
@@ -272,9 +272,10 @@ let importPathForReasonModuleName ~(config : Config.t) ~outputFileRelative
   | shimModuleName ->
     if !Debug.moduleResolution then
       Log_.item "ShimModuleName: %s\n" (shimModuleName |> ModuleName.toString);
+    let importExtension = ModuleExtension.shimTsOutputFileExtension ~config in
     let importPath =
-      resolveModule ~config ~importExtension:".shim" ~outputFileRelative
-        ~resolver ~useBsDependencies:false shimModuleName
+      resolveModule ~config ~importExtension ~outputFileRelative ~resolver
+        ~useBsDependencies:false shimModuleName
     in
     if !Debug.moduleResolution then
       Log_.item "Import Path: %s\n" (importPath |> ImportPath.dump);

jscomp/gentype/Paths.ml

@@ -29,7 +29,7 @@ let findNameSpace cmt =
   |> keepAfterDash
 
 let getOutputFileRelative ~config cmt =
-  (cmt |> handleNamespace) ^ EmitType.outputFileSuffix ~config
+  (cmt |> handleNamespace) ^ ModuleExtension.tsInputFileSuffix ~config
 
 let getOutputFile ~(config : Config.t) cmt =
   Filename.concat config.projectRoot (getOutputFileRelative ~config cmt)

jscomp/gentype_tests/typescript-react-example/package.json

@@ -14,9 +14,9 @@
     "tsc": "tsc -p tsconfig.json"
   },
   "devDependencies": {
-    "@types/node": "^13.13.4",
-    "@types/react-dom": "^16.9.7",
+    "@types/node": "^18.15.12",
+    "@types/react-dom": "^18.0.11",
     "rescript": "file:../../..",
-    "typescript": "3.9.2"
+    "typescript": "^5.0.4"
   }
 }