Fix Gentype: Support mutual recursion in types (#6528)

* In GenType Add mutual recursive test

Signed-Off-By:  Jono Prest <jjprest@gmail.com>

* In GenType add support for mutual recursion

Signed-Off-By: Jono Prest <jjprest@gmail.com>

* Refactor GenType support mutual type recursion
Signed-Off-By: Jono Prest <jjprest@gmail.com>

---------

Signed-off-by: Jono Prest <jjprest@gmail.com>

Author: JonoPrest

CHANGELOG.md

@@ -21,6 +21,7 @@
 - Add missing check that the runtime representation of variants matches implementation and interface. https://github.com/rescript-lang/rescript-compiler/pull/6513/files
 - GenType: only export types (not values) from module types. https://github.com/rescript-lang/rescript-compiler/pull/6516
 - Fix compiler crash with unboxed variant definition with only 1 constructor. https://github.com/rescript-lang/rescript-compiler/pull/6523
+- GenType: support mutual recursive types inside modules. https://github.com/rescript-lang/rescript-compiler/pull/6528
 
 # 11.0.0-rc.7
 

jscomp/gentype/TranslateTypeDeclarations.ml

@@ -313,13 +313,12 @@ let hasSomeGADTLeaf constructorDeclarations =
     (fun declaration -> declaration.Types.cd_res != None)
     constructorDeclarations
 
-let translateTypeDeclaration ~config ~outputFileRelative ~recursive ~resolver
-    ~typeEnv
+let translateTypeDeclaration ~config ~outputFileRelative ~resolver ~typeEnv
     ({typ_attributes; typ_id; typ_loc; typ_manifest; typ_params; typ_type} :
       Typedtree.type_declaration) : CodeItem.typeDeclaration list =
   if !Debug.translation then
     Log_.item "Translate Type Declaration %s\n" (typ_id |> Ident.name);
-  if recursive then typeEnv |> TypeEnv.newType ~name:(typ_id |> Ident.name);
+
   let typeName = Ident.name typ_id in
   let typeVars =
     typ_params
@@ -335,19 +334,27 @@ let translateTypeDeclaration ~config ~outputFileRelative ~recursive ~resolver
     | Type_abstract -> GeneralDeclaration typ_manifest
     | _ -> NoDeclaration
   in
-  let res =
-    declarationKind
-    |> traslateDeclarationKind ~config ~loc:typ_loc ~outputFileRelative
-         ~resolver ~typeAttributes:typ_attributes ~typeEnv ~typeName ~typeVars
-  in
-  if not recursive then typeEnv |> TypeEnv.newType ~name:(typ_id |> Ident.name);
-  res
+  declarationKind
+  |> traslateDeclarationKind ~config ~loc:typ_loc ~outputFileRelative ~resolver
+       ~typeAttributes:typ_attributes ~typeEnv ~typeName ~typeVars
+
+let addTypeDeclarationIdToTypeEnv ~typeEnv
+    ({typ_id} : Typedtree.type_declaration) =
+  typeEnv |> TypeEnv.newType ~name:(typ_id |> Ident.name)
 
 let translateTypeDeclarations ~config ~outputFileRelative ~recursive ~resolver
     ~typeEnv (typeDeclarations : Typedtree.type_declaration list) :
     CodeItem.typeDeclaration list =
+  if recursive then
+    typeDeclarations |> List.iter (addTypeDeclarationIdToTypeEnv ~typeEnv);
   typeDeclarations
-  |> List.map
-       (translateTypeDeclaration ~config ~outputFileRelative ~recursive
-          ~resolver ~typeEnv)
+  |> List.map (fun typeDeclaration ->
+         let res =
+           typeDeclaration
+           |> translateTypeDeclaration ~config ~outputFileRelative ~resolver
+                ~typeEnv
+         in
+         if not recursive then
+           typeDeclaration |> addTypeDeclarationIdToTypeEnv ~typeEnv;
+         res)
   |> List.concat

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

@@ -8,3 +8,7 @@ export type notRecursive = number;
 export type M_notRecursive = notRecursive[];
 
 export type M_recursive = { readonly self: M_recursive };
+
+export type M_mutualRecursive = { readonly a: M_a };
+
+export type M_a = { readonly self: M_mutualRecursive };

jscomp/gentype_tests/typescript-react-example/src/NonrecursiveTypes.gen.tsx

@@ -7,4 +7,8 @@ module M = {
 
   @genType
   type rec recursive = {self: recursive}
+
+  @genType
+  type rec mutualRecursive = {a: a}
+  and a = {self: mutualRecursive}
 }