Update CHANGELOG.md

Author: cristianoc

CHANGELOG.md

@@ -26,7 +26,7 @@ subset of the arguments, and return a curried type with the remaining ones https
 - Add support for toplevel `await` https://github.com/rescript-lang/rescript-compiler/pull/5940
 - Support optional named arguments without a final unit in uncurried functions https://github.com/rescript-lang/rescript-compiler/pull/5907
 - Add experimental suppport for directives. An annotation such as `@@directive("use client;")` emits `use client;` verbatim before imports https://github.com/rescript-lang/rescript-compiler/pull/5998
-- Add `Core` standard library support for `genType` https://github.com/rescript-lang/rescript-compiler/pull/6019
+- `genType`: add `Core` standard library support for the following builtin types: `Null.t`, `Nullable.t`, `Undefined.t`, `Dict.t<_>`, `Promise.t<_>`, `Date.t`, `BigInt.t`, `RegExp.t`, `Map.t<_, _>`, `WeakMap.t<_, _>`, `Set<_>`, `WeakSet<_>` https://github.com/rescript-lang/rescript-compiler/pull/6019
 
 #### :boom: Breaking Change
 

jscomp/gentype/Converter.ml

@@ -250,7 +250,7 @@ let typeGetConverterNormalized ~config ~inline ~lookupId ~typeNameIsInterface
     | TypeVar _ -> (IdentC, normalized_)
     | Undefined t ->
       let tConverter, tNormalized = t |> visit ~visited in
-      (OptionC tConverter, Undefined tNormalized)
+      (NullableC tConverter, Undefined tNormalized)
     | Variant variant ->
       let allowUnboxed = not variant.polymorphic in
       let withPayloads, normalized, unboxed =

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

@@ -14,15 +14,9 @@ export const nullable0: (x:(null | undefined | number)) => (null | undefined | n
 
 export const nullable1: (x:(null | undefined | number)) => (null | undefined | number) = CoreBS.nullable1;
 
-export const undefined0: (x:(undefined | number)) => (undefined | number) = function (Arg1: any) {
-  const result = CoreBS.undefined0((Arg1 == null ? undefined : Arg1));
-  return result
-};
-
-export const undefined1: (x:(undefined | number)) => (undefined | number) = function (Arg1: any) {
-  const result = CoreBS.undefined1((Arg1 == null ? undefined : Arg1));
-  return result
-};
+export const undefined0: (x:(undefined | number)) => (undefined | number) = CoreBS.undefined0;
+
+export const undefined1: (x:(undefined | number)) => (undefined | number) = CoreBS.undefined1;
 
 export const dict0: (x:{[id: string]: string}) => {[id: string]: string} = CoreBS.dict0;