[tcgc] add crossLanguagePackageId (Azure#649)

Co-authored-by: iscai-msft <[email protected]>

.chronus/changes/add_package_id-2024-3-9-18-55-43.md

@@ -0,0 +1,7 @@
+---
+changeKind: feature
+packages:
+  - "@azure-tools/typespec-client-generator-core"
+---
+
+add `.crossLanguagePackageId` onto `SdkContext` types. This is a package id that is shared across languages, allowing linkage between packages generated across different languages

packages/typespec-client-generator-core/src/interfaces.ts

@@ -546,6 +546,7 @@ export interface SdkPackage<TServiceOperation extends SdkServiceOperation> {
    * @deprecated This property is deprecated. Look at `.diagnostics` on SdkContext instead
    */
   diagnostics: readonly Diagnostic[];
+  crossLanguagePackageId: string;
 }
 
 export type SdkHttpPackage = SdkPackage<SdkHttpOperation>;

packages/typespec-client-generator-core/src/package.ts

@@ -59,6 +59,7 @@ import {
 import { createDiagnostic } from "./lib.js";
 import {
   getClientNamespaceString,
+  getCrossLanguagePackageId,
   getDefaultApiVersion,
   getEffectivePayloadType,
   getHttpOperationWithCache,
@@ -562,12 +563,14 @@ export function getSdkPackage<
   for (const client of listClients(context)) {
     createSdkClientType(context, client);
   }
+  const crossLanguagePackageId = diagnostics.pipe(getCrossLanguagePackageId(context));
   return {
     name: getClientNamespaceString(context)!,
     rootNamespace: getClientNamespaceString(context)!,
     clients: Array.from(context.__clients.values()),
     models: modelsAndEnums.filter((x): x is SdkModelType => x.kind === "model"),
     enums: modelsAndEnums.filter((x): x is SdkEnumType => x.kind === "enum"),
     diagnostics: diagnostics.diagnostics,
+    crossLanguagePackageId,
   };
 }