From 6aad4a795f7dc4f686e83453bf237b80d03295e0 Mon Sep 17 00:00:00 2001
From: Timothee Guerin <tiguerin@microsoft.com>
Date: Mon, 22 Jul 2024 15:25:40 -0700
Subject: [PATCH] Add `const` template parameter to get the precise lib type
 (#3933)

Without that there is some loss of information
---
 .chronus/changes/lib-const-2024-6-22-22-3-25.md        |  8 ++++++++
 .chronus/changes/lib-const-2024-6-22-22-3-26.md        | 10 ++++++++++
 packages/compiler/src/core/library.ts                  |  6 +++---
 packages/compiler/src/core/param-message.ts            |  2 +-
 .../http-server-javascript/src/common/reference.ts     |  2 +-
 packages/http/src/payload.ts                           |  2 +-
 packages/http/test/multipart.test.ts                   |  2 +-
 packages/protobuf/src/transform/index.ts               |  2 +-
 8 files changed, 26 insertions(+), 8 deletions(-)
 create mode 100644 .chronus/changes/lib-const-2024-6-22-22-3-25.md
 create mode 100644 .chronus/changes/lib-const-2024-6-22-22-3-26.md

diff --git a/.chronus/changes/lib-const-2024-6-22-22-3-25.md b/.chronus/changes/lib-const-2024-6-22-22-3-25.md
new file mode 100644
index 0000000000..c17edf07da
--- /dev/null
+++ b/.chronus/changes/lib-const-2024-6-22-22-3-25.md
@@ -0,0 +1,8 @@
+---
+# Change versionKind to one of: internal, fix, dependencies, feature, deprecation, breaking
+changeKind: fix
+packages:
+  - "@typespec/compiler"
+---
+
+Add `const` template parameter to get the precise lib type
diff --git a/.chronus/changes/lib-const-2024-6-22-22-3-26.md b/.chronus/changes/lib-const-2024-6-22-22-3-26.md
new file mode 100644
index 0000000000..e6c475b297
--- /dev/null
+++ b/.chronus/changes/lib-const-2024-6-22-22-3-26.md
@@ -0,0 +1,10 @@
+---
+# Change versionKind to one of: internal, fix, dependencies, feature, deprecation, breaking
+changeKind: fix
+packages:
+  - "@typespec/http-server-javascript"
+  - "@typespec/http"
+  - "@typespec/protobuf"
+---
+
+Fix some diagnostic not showing the right message
diff --git a/packages/compiler/src/core/library.ts b/packages/compiler/src/core/library.ts
index a8025ef17a..e9041ea85a 100644
--- a/packages/compiler/src/core/library.ts
+++ b/packages/compiler/src/core/library.ts
@@ -63,9 +63,9 @@ function createStateKeys<T extends string>(
  * const lib = createTypeSpecLibrary(libDef);
  */
 export function createTypeSpecLibrary<
-  T extends { [code: string]: DiagnosticMessages },
-  E extends Record<string, any>,
-  State extends string = never,
+  const T extends { [code: string]: DiagnosticMessages },
+  const E extends Record<string, any>,
+  const State extends string = never,
 >(lib: Readonly<TypeSpecLibraryDef<T, E, State>>): TypeSpecLibrary<T, E, State> {
   let emitterOptionValidator: JSONSchemaValidator;
 
diff --git a/packages/compiler/src/core/param-message.ts b/packages/compiler/src/core/param-message.ts
index df35803a69..8e8e5365ca 100644
--- a/packages/compiler/src/core/param-message.ts
+++ b/packages/compiler/src/core/param-message.ts
@@ -1,6 +1,6 @@
 import type { CallableMessage } from "./types.js";
 
-export function paramMessage<T extends string[]>(
+export function paramMessage<const T extends string[]>(
   strings: readonly string[],
   ...keys: T
 ): CallableMessage<T> {
diff --git a/packages/http-server-javascript/src/common/reference.ts b/packages/http-server-javascript/src/common/reference.ts
index 7feeb3d69c..e6af69fa18 100644
--- a/packages/http-server-javascript/src/common/reference.ts
+++ b/packages/http-server-javascript/src/common/reference.ts
@@ -253,7 +253,7 @@ export function emitTypeReference(
         default:
           reportDiagnostic(ctx.program, {
             code: "unrecognized-intrinsic",
-            format: { name: (type satisfies never as IntrinsicType).name },
+            format: { intrinsic: (type satisfies never as IntrinsicType).name },
             target: position,
           });
           return "unknown";
diff --git a/packages/http/src/payload.ts b/packages/http/src/payload.ts
index fda7a5536a..1beeeeef08 100644
--- a/packages/http/src/payload.ts
+++ b/packages/http/src/payload.ts
@@ -345,7 +345,7 @@ function resolveMultiPartBodyFromTuple(
       diagnostics.add(
         createDiagnostic({
           code: "multipart-invalid-content-type",
-          format: { contentType, valid: multipartContentTypesValues.join(", ") },
+          format: { contentType, supportedContentTypes: multipartContentTypesValues.join(", ") },
           target: type,
         })
       );
diff --git a/packages/http/test/multipart.test.ts b/packages/http/test/multipart.test.ts
index 19989fd379..735a2e8e27 100644
--- a/packages/http/test/multipart.test.ts
+++ b/packages/http/test/multipart.test.ts
@@ -13,7 +13,7 @@ it("emit diagnostic when using invalid content type for multipart ", async () =>
   expectDiagnostics(diagnostics, {
     code: "@typespec/http/multipart-invalid-content-type",
     message:
-      "Content type 'application/json' is not a multipart content type. Supported content types are: .",
+      "Content type 'application/json' is not a multipart content type. Supported content types are: multipart/form-data, multipart/mixed.",
   });
 });
 
diff --git a/packages/protobuf/src/transform/index.ts b/packages/protobuf/src/transform/index.ts
index 8a17febf32..1d506a9ebf 100644
--- a/packages/protobuf/src/transform/index.ts
+++ b/packages/protobuf/src/transform/index.ts
@@ -442,7 +442,7 @@ function tspToProto(program: Program, emitterOptions: ProtobufEmitterOptions): P
 
     reportDiagnostic(program, {
       code: "unsupported-intrinsic",
-      format: { type: t.name },
+      format: { name: t.name },
       target: t,
     });