Allow recursive types.

Fixes rescript-association/genType#585

Author: cristianoc

CHANGELOG.md

@@ -85,6 +85,7 @@ These are only breaking changes for unformatted code.
 - Change the compilation of pattern matching for variants so it does not depends on variats being integers https://github.com/rescript-lang/rescript-compiler/pull/6085
 - Improve code generated for string templates https://github.com/rescript-lang/rescript-compiler/pull/6090
 - Move Jsx and JsxDOM and JsxEvent and JsxPPXReactSupport inside Pervasives and build them separately for curried and uncurried mode https://github.com/rescript-lang/rescript-compiler/pull/6091
+- Gentype: allow recursive data types https://github.com/rescript-association/genType/issues/585
 
 # 10.1.4
 

jscomp/gentype/Converter.ml

@@ -1,19 +1,13 @@
 open GenTypeCommon
 
-type t =
-  | CircularC of string * t
-  | IdentC
-  | OptionC of t
-  | PromiseC of t
-  | TupleC of t list
+type t = IdentC | OptionC of t | PromiseC of t | TupleC of t list
 
 and groupedArgConverter =
   | ArgConverter of t
   | GroupConverter of (string * optional * t) list
 
 let rec toString converter =
   match converter with
-  | CircularC (s, c) -> "circular(" ^ s ^ " " ^ toString c ^ ")"
   | IdentC -> "id"
   | OptionC c -> "option(" ^ toString c ^ ")"
   | PromiseC c -> "promise(" ^ toString c ^ ")"
@@ -51,6 +45,7 @@ let typeGetConverterNormalized ~config ~inline ~lookupId ~typeNameIsInterface
         circular := name;
         (IdentC, normalized_))
       else
+        let visited = visited |> StringSet.add name in
         match name |> lookupId with
         | {CodeItem.annotation = GenTypeOpaque} -> (IdentC, normalized_)
         | {annotation = NoGenType} -> (IdentC, normalized_)
@@ -140,16 +135,11 @@ let typeGetConverterNormalized ~config ~inline ~lookupId ~typeNameIsInterface
       (converter, {aName; aType = tNormalized})
   in
   let converter, normalized = type0 |> visit ~visited:StringSet.empty in
-  let finalConverter =
-    match !circular <> "" with
-    | true -> CircularC (!circular, converter)
-    | false -> converter
-  in
   if !Debug.converter then
     Log_.item "Converter type0:%s converter:%s\n"
       (type0 |> EmitType.typeToString ~config ~typeNameIsInterface)
-      (finalConverter |> toString);
-  (finalConverter, normalized)
+      (converter |> toString);
+  (converter, normalized)
 
 let typeGetConverter ~config ~lookupId ~typeNameIsInterface type_ =
   type_
@@ -164,7 +154,6 @@ let typeGetNormalized ~config ~inline ~lookupId ~typeNameIsInterface type_ =
 
 let rec converterIsIdentity ~config ~toJS converter =
   match converter with
-  | CircularC (_, c) -> c |> converterIsIdentity ~config ~toJS
   | IdentC -> true
   | OptionC c -> c |> converterIsIdentity ~config ~toJS
   | PromiseC c -> c |> converterIsIdentity ~config ~toJS
@@ -175,12 +164,6 @@ let rec apply ~(config : Config.t) ~converter ~indent ~nameGen ~toJS
     ~variantTables value =
   match converter with
   | _ when converter |> converterIsIdentity ~config ~toJS -> value
-  | CircularC (s, c) ->
-    value
-    |> EmitText.addComment
-         ~comment:
-           ("WARNING: circular type " ^ s ^ ". Only shallow converter applied.")
-    |> apply ~config ~converter:c ~indent ~nameGen ~toJS ~variantTables
   | IdentC -> value
   | OptionC c ->
     EmitText.parens

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

@@ -6,6 +6,8 @@
 import * as VariantsBS__Es6Import from './Variants.bs';
 const VariantsBS: any = VariantsBS__Es6Import;
 
+import type {list} from '../src/shims/RescriptPervasives.shim';
+
 // tslint:disable-next-line:interface-over-type-literal
 export type weekday = 
     "monday"
@@ -35,6 +37,12 @@ export type x2 = "x" | "same";
 export type type_ = "type";
 export type type = type_;
 
+// tslint:disable-next-line:interface-over-type-literal
+export type myList = "E" | { TAG: "C"; _0: number; _1: myList };
+
+// tslint:disable-next-line:interface-over-type-literal
+export type builtinList = list<number>;
+
 // tslint:disable-next-line:interface-over-type-literal
 export type result1<a,b> = 
     { TAG: "Ok"; _0: a }

jscomp/gentype_tests/typescript-react-example/src/Variants.res

@@ -79,6 +79,12 @@ type testGenTypeAs3 = [
 @genType @genType.as("type")
 type type_ = | @genType.as("type") Type
 
+@genType
+type rec myList = E | C(int, myList)
+
+@genType
+type builtinList = list<int>
+
 @genType
 let polyWithOpt = foo =>
   foo === "bar"