Fixed an issue with nested state.matches calls causing state to be …

…narrowed to `never` when the typegen was involved (#3077)

.changeset/pink-rabbits-kick.md

@@ -0,0 +1,5 @@
+---
+'xstate': patch
+---
+
+Fixed an issue with nested `state.matches` calls when the typegen was involved. The `state` ended up being `never` and thus not usable.

packages/core/src/State.ts

@@ -319,7 +319,12 @@ export class State<
   public matches<
     TSV extends TResolvedTypesMeta extends TypegenEnabled
       ? Prop<TResolvedTypesMeta, 'matchesStates'>
-      : TTypestate['value']
+      : never
+  >(parentStateValue: TSV): boolean;
+  public matches<
+    TSV extends TResolvedTypesMeta extends TypegenDisabled
+      ? TTypestate['value']
+      : never
   >(
     parentStateValue: TSV
   ): this is State<
@@ -332,7 +337,8 @@ export class State<
     TStateSchema,
     TTypestate,
     TResolvedTypesMeta
-  > & { value: TSV } {
+  > & { value: TSV };
+  public matches(parentStateValue: StateValue): any {
     return matchesState(parentStateValue as StateValue, this.value);
   }
 

packages/core/test/typegenTypes.test.ts

@@ -1135,6 +1135,27 @@ describe('typegen types', () => {
     }
   });
 
+  it("shouldn't end up with `never` within a branch after two `state.matches` calls", () => {
+    interface TypesMeta extends TypegenMeta {
+      matchesStates: 'a' | 'a.b';
+    }
+
+    const machine = createMachine({
+      tsTypes: {} as TypesMeta,
+      schema: {
+        context: {} as {
+          foo: string;
+        }
+      }
+    });
+
+    const state = machine.initialState;
+
+    if (state.matches('a') && state.matches('a.b')) {
+      ((_accept: string) => {})(state.context.foo);
+    }
+  });
+
   it('should be possible to pass typegen-less machines to functions expecting a machine argument that do not utilize the typegen information', () => {
     const machine = createMachine({});