Fix: `resolveUsage` shouldn't include model `extends` (#1485)

common/changes/@cadl-lang/compiler/resolve-usage-no-extends_2022-12-28-18-00.json

@@ -0,0 +1,10 @@
+{
+  "changes": [
+    {
+      "packageName": "@cadl-lang/compiler",
+      "comment": "Fix: `resolveUsages` shouldn't include base model",
+      "type": "none"
+    }
+  ],
+  "packageName": "@cadl-lang/compiler"
+}

packages/compiler/core/helpers/usage-resolver.ts

@@ -108,7 +108,6 @@ function navigateReferencedTypes(
       callback(type);
       navigateIterable(type.properties, callback, visited);
       navigateIterable(type.derivedModels, callback, visited);
-      type.baseModel && navigateReferencedTypes(type.baseModel, callback, visited);
       type.indexer?.value && navigateReferencedTypes(type.indexer.value, callback, visited);
       break;
     case "ModelProperty":

packages/compiler/test/helpers/usage-resolver.test.ts

@@ -92,14 +92,14 @@ describe("compiler: helpers: usage resolver", () => {
     deepStrictEqual(usages, { inputs: [], outputs: ["Foo", "Bar"] });
   });
 
-  it("track model referenced via base model in returnType", async () => {
+  it("doesn't track model referenced via base model in returnType", async () => {
     const usages = await getUsages(`
       model Bar {}
       model Foo extends Bar {}
       op test(): Foo;
     `);
 
-    deepStrictEqual(usages, { inputs: [], outputs: ["Foo", "Bar"] });
+    deepStrictEqual(usages, { inputs: [], outputs: ["Foo"] });
   });
 
   it("track model referenced via child model in returnType", async () => {