From 1ef6606416a46e25feb90bb386617149ea98f65f Mon Sep 17 00:00:00 2001
From: Timothee Guerin <tiguerin@microsoft.com>
Date: Wed, 13 Dec 2023 08:37:34 -0800
Subject: [PATCH 1/3] OpenAPI3 multipart conflict

---
 packages/openapi3/src/schema-emitter.ts  |  2 +-
 packages/openapi3/test/multipart.test.ts | 17 +++++++++++++++++
 2 files changed, 18 insertions(+), 1 deletion(-)

diff --git a/packages/openapi3/src/schema-emitter.ts b/packages/openapi3/src/schema-emitter.ts
index 7e553e8d81..8010591d54 100644
--- a/packages/openapi3/src/schema-emitter.ts
+++ b/packages/openapi3/src/schema-emitter.ts
@@ -125,7 +125,7 @@ export class OpenAPI3SchemaEmitter extends TypeEmitter<
     const contentType = this.#getContentType();
 
     if (contentType === "application/json") {
-      delete patch.contentType;
+      patch.contentType = undefined;
     }
 
     return patch;
diff --git a/packages/openapi3/test/multipart.test.ts b/packages/openapi3/test/multipart.test.ts
index aaf66a0c88..ddbcedd1a3 100644
--- a/packages/openapi3/test/multipart.test.ts
+++ b/packages/openapi3/test/multipart.test.ts
@@ -102,4 +102,21 @@ describe("typespec-autorest: multipart", () => {
       }
     );
   });
+
+  it("enum used in both a json payload and multipart part shouldn't create 2 models", async () => {
+    const res = await openApiFor(
+      `
+      enum FilePurpose {
+        fineTune,
+        fineTuneResults,
+      }
+      
+      interface Files {
+        @get listFiles(purpose: FilePurpose): string;
+        @post uploadFile(@header contentType: "multipart/form-data", purpose: FilePurpose): string;
+      }
+      `
+    );
+    deepStrictEqual(res.components.schemas.FilePurpose, {});
+  });
 });

From 4f741b8b64d312c1663e2583d43ab44257272fe7 Mon Sep 17 00:00:00 2001
From: Timothee Guerin <tiguerin@microsoft.com>
Date: Wed, 13 Dec 2023 08:39:04 -0800
Subject: [PATCH 2/3] Changelog

---
 ...x-openapi3-multipart-conflict_2023-12-13-16-39.json | 10 ++++++++++
 1 file changed, 10 insertions(+)
 create mode 100644 common/changes/@typespec/openapi3/hotfix-openapi3-multipart-conflict_2023-12-13-16-39.json

diff --git a/common/changes/@typespec/openapi3/hotfix-openapi3-multipart-conflict_2023-12-13-16-39.json b/common/changes/@typespec/openapi3/hotfix-openapi3-multipart-conflict_2023-12-13-16-39.json
new file mode 100644
index 0000000000..29dd0a23e5
--- /dev/null
+++ b/common/changes/@typespec/openapi3/hotfix-openapi3-multipart-conflict_2023-12-13-16-39.json
@@ -0,0 +1,10 @@
+{
+  "changes": [
+    {
+      "packageName": "@typespec/openapi3",
+      "comment": "Fix: OpenAPI3 creating conflicting type declaration when type was used in multipart implicit body and json body",
+      "type": "none"
+    }
+  ],
+  "packageName": "@typespec/openapi3"
+}
\ No newline at end of file

From b0e834ccd22cd5881911b53d478b7b508da3b84f Mon Sep 17 00:00:00 2001
From: Timothee Guerin <tiguerin@microsoft.com>
Date: Wed, 13 Dec 2023 08:39:56 -0800
Subject: [PATCH 3/3] Fix test

---
 packages/openapi3/test/multipart.test.ts | 6 +++---
 1 file changed, 3 insertions(+), 3 deletions(-)

diff --git a/packages/openapi3/test/multipart.test.ts b/packages/openapi3/test/multipart.test.ts
index ddbcedd1a3..e64ddc9f2f 100644
--- a/packages/openapi3/test/multipart.test.ts
+++ b/packages/openapi3/test/multipart.test.ts
@@ -107,8 +107,8 @@ describe("typespec-autorest: multipart", () => {
     const res = await openApiFor(
       `
       enum FilePurpose {
-        fineTune,
-        fineTuneResults,
+        one,
+        two,
       }
       
       interface Files {
@@ -117,6 +117,6 @@ describe("typespec-autorest: multipart", () => {
       }
       `
     );
-    deepStrictEqual(res.components.schemas.FilePurpose, {});
+    deepStrictEqual(res.components.schemas.FilePurpose, { type: "string", enum: ["one", "two"] });
   });
 });