From aaae51a69fb546748d4d657cbfc03dbd13611df6 Mon Sep 17 00:00:00 2001
From: Timothee Guerin <tiguerin@microsoft.com>
Date: Mon, 7 Oct 2024 10:40:32 -0700
Subject: [PATCH] Project source models (#4445)

fix [#4280](https://github.com/microsoft/typespec/issues/4280)

---------

Co-authored-by: Christopher Radek <14189820+chrisradek@users.noreply.github.com>
---
 ...x-project-source-models-2024-8-13-15-15-44.md |  7 +++++++
 packages/compiler/src/core/projector.ts          |  4 ++++
 .../test/projection/projector-identity.test.ts   | 16 ++++++++++++++++
 3 files changed, 27 insertions(+)
 create mode 100644 .chronus/changes/fix-project-source-models-2024-8-13-15-15-44.md

diff --git a/.chronus/changes/fix-project-source-models-2024-8-13-15-15-44.md b/.chronus/changes/fix-project-source-models-2024-8-13-15-15-44.md
new file mode 100644
index 0000000000..9687ec4a92
--- /dev/null
+++ b/.chronus/changes/fix-project-source-models-2024-8-13-15-15-44.md
@@ -0,0 +1,7 @@
+---
+changeKind: fix
+packages:
+  - "@typespec/compiler"
+---
+
+[API] model `sourceModels` property are now projected correctly
diff --git a/packages/compiler/src/core/projector.ts b/packages/compiler/src/core/projector.ts
index ea455acdc9..60821d1b72 100644
--- a/packages/compiler/src/core/projector.ts
+++ b/packages/compiler/src/core/projector.ts
@@ -302,6 +302,10 @@ export function createProjector(
       projectedModel.sourceModel = projectType(model.sourceModel) as Model;
     }
 
+    projectedModel.sourceModels = model.sourceModels.map((source) => {
+      return { ...source, model: projectType(source.model) as Model };
+    });
+
     if (model.indexer) {
       const projectedValue = projectType(model.indexer.value);
       projectedModel.indexer = {
diff --git a/packages/compiler/test/projection/projector-identity.test.ts b/packages/compiler/test/projection/projector-identity.test.ts
index 902e419c75..5a0bfdb85c 100644
--- a/packages/compiler/test/projection/projector-identity.test.ts
+++ b/packages/compiler/test/projection/projector-identity.test.ts
@@ -126,6 +126,22 @@ describe("compiler: projector: Identity", () => {
       strictEqual(projectResult.type.properties.get("name")?.model, projectResult.type);
     });
 
+    it("link projected model with sourceModels", async () => {
+      const code = `
+        @test("target") model Foo is Bar {
+          ...Spreadable
+        }
+        model Bar {}
+        model Spreadable {}
+      `;
+      const projectResult = await projectWithNoChange(code, "Model");
+      const [sourceBar, sourceSpreadable] = projectResult.type.sourceModels.map((x) => x.model);
+      const Spreadable = projectResult.globalNamespace.models.get("Spreadable")!;
+      const Bar = projectResult.globalNamespace.models.get("Bar")!;
+      strictEqual(sourceBar, Bar);
+      strictEqual(sourceSpreadable, Spreadable);
+    });
+
     it("link projected property with sourceProperty", async () => {
       const code = `
         @test("target") model Foo {