Enable semantic highlighting support for the C++ language client

Signed-off-by: Nathan Ridge <zeratul976@hotmail.com>

packages/cpp/src/browser/cpp-language-client-contribution.ts

@@ -15,12 +15,14 @@
  ********************************************************************************/
 
 import { inject, injectable, postConstruct } from 'inversify';
+import { MessageConnection } from 'vscode-jsonrpc';
 import {
     BaseLanguageClientContribution, LanguageClientFactory,
     LanguageClientOptions,
     ILanguageClient
 } from '@theia/languages/lib/browser';
 import { Languages, Workspace } from '@theia/languages/lib/browser';
+import { SemanticHighlightingService } from '@theia/editor/lib/browser/semantic-highlight/semantic-highlighting-service';
 import { ILogger } from '@theia/core/lib/common/logger';
 import { WindowService } from '@theia/core/lib/browser/window/window-service';
 import { CPP_LANGUAGE_ID, CPP_LANGUAGE_NAME, HEADER_AND_SOURCE_FILE_EXTENSIONS, CppStartParameters } from '../common';
@@ -62,6 +64,7 @@ export class CppLanguageClientContribution extends BaseLanguageClientContributio
         @inject(Workspace) protected readonly workspace: Workspace,
         @inject(Languages) protected readonly languages: Languages,
         @inject(LanguageClientFactory) protected readonly languageClientFactory: LanguageClientFactory,
+        @inject(SemanticHighlightingService) protected readonly semanticHighlightingService: SemanticHighlightingService,
     ) {
         super(workspace, languages, languageClientFactory);
     }
@@ -83,6 +86,12 @@ export class CppLanguageClientContribution extends BaseLanguageClientContributio
         this.cppBuildConfigurationsStatusBarElement.show();
     }
 
+    protected createLanguageClient(connection: MessageConnection): ILanguageClient {
+        const client: ILanguageClient & Readonly<{ languageId: string }> = Object.assign(super.createLanguageClient(connection), { languageId: this.id });
+        client.registerFeature(SemanticHighlightingService.createNewFeature(this.semanticHighlightingService, client));
+        return client;
+    }
+
     private createClangdConfigurationParams(config: CppBuildConfiguration | undefined): ClangdConfigurationParamsChange {
         const clangdParams: ClangdConfigurationParamsChange = {};