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");
+    });
 });