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

@@ -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

.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

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;
 

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> {

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";

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,
         })
       );

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.",
   });
 });
 

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,
     });