Fix references to mapped type aliases

Resolves #2954

Author: Gerrit0

CHANGELOG.md

@@ -4,6 +4,10 @@ title: Changelog
 
 ## Unreleased
 
+### Bug Fixes
+
+- References to type aliases defined as mapped types will now correctly create a reference to the type alias, #2954.
+
 ## v0.28.4 (2025-05-04)
 
 ### Features

src/lib/converter/types.ts

@@ -792,6 +792,17 @@ const referenceConverter: TypeConverter<
  return ref;
  }
 
+ // #2954 mapped type aliases are special! The type that we have here will
+ // not point at the type alias which names it like we want, but instead at
+ // the mapped type instantiation. Fall back to converting via the original
+ // type node to avoid creating a reference which points to the mapped type.
+ if (
+ originalNode && ts.isTypeReferenceNode(originalNode) && isObjectType(type) &&
+ type.objectFlags & ts.ObjectFlags.Mapped
+ ) {
+ return referenceConverter.convert(context, originalNode);
+ }
+
  let name: string;
  if (ts.isIdentifier(node.typeName)) {
  name = node.typeName.text;

src/test/converter2/issues/gh2954.ts

@@ -0,0 +1,11 @@
+export type AliasA = Readonly<Record<string, string>>;
+
+export type AliasB<T> = Readonly<Record<string, T>>;
+
+export type AliasC = Readonly<{}>;
+
+export interface InterfaceA {
+ propertyA: AliasA;
+ propertyB: AliasB<string>;
+ propertyC: AliasC;
+}

src/test/issues.c2.test.ts

@@ -2133,4 +2133,11 @@ describe("Issue Tests", () => {
  const project = convert();
  equal(query(project, "Test").type?.toString(), "() => Promise<any>");
  });
+
+ it("#2954 handles Readonly with Record type", () => {
+ const project = convert();
+ equal(query(project, "InterfaceA.propertyA").type?.toString(), "AliasA");
+ equal(query(project, "InterfaceA.propertyB").type?.toString(), "AliasB<string>");
+ equal(query(project, "InterfaceA.propertyC").type?.toString(), "AliasC");
+ });
 });