prevent infinite recursion of ContainsFragmentsRefs type

src/masking/__benches__/types.bench.ts

@@ -577,3 +577,18 @@ test("detects `$fragmentRefs` on types with index signatures", (prefix) => {
     }>();
   });
 });
+
+test("recursive types: no error 'Type instantiation is excessively deep and possibly infinite.'", (prefix) => {
+  // this type is self-recursive
+  type Source = import("graphql").IntrospectionQuery;
+
+  bench(prefix + "instantiations", () => {
+    return {} as MaybeMasked<Source>;
+  }).types([6, "instantiations"]);
+
+  bench(prefix + "functionality", () => {
+    const x = {} as MaybeMasked<Source>;
+
+    expectTypeOf(x).branded.toEqualTypeOf<Source>();
+  });
+});

src/masking/internal/types.ts

@@ -182,10 +182,13 @@ export type RemoveMaskedMarker<T> = Omit<T, "__masked">;
 export type RemoveFragmentName<T> =
   T extends any ? Omit<T, " $fragmentName"> : T;
 
-export type ContainsFragmentsRefs<TData> =
-  true extends IsAny<TData> ? false
-  : TData extends object ?
-    " $fragmentRefs" extends keyof RemoveIndexSignature<TData> ?
-      true
-    : ContainsFragmentsRefs<TData[keyof TData]>
-  : false;
+type Exact<in out T> = (x: T) => T;
+export type ContainsFragmentsRefs<TData, Seen = never> = true extends (
+  IsAny<TData>
+) ?
+  false
+: TData extends object ?
+  Exact<TData> extends Seen ? false
+  : " $fragmentRefs" extends keyof RemoveIndexSignature<TData> ? true
+  : ContainsFragmentsRefs<TData[keyof TData], Seen | Exact<TData>>
+: false;