[clangd] in VSCode client, filter extensions properly and only accept file: URIs

[sammccall]

Summary

The filtering wasn't previously working as intended - the string list is
interpreted as a list of editor modes, not file extensions.
(It happens to mostly work as "c" and "cpp" are the names of modes, but we're
missing objective-c)

The file: restriction is new - clangd needs to be able to convert URI<->path
in order to determine how to build.

[hokein]

LGTM.

clangd/clients/clangd-vscode/src/extension.ts

25–26

nit: maybe use ' to be consistent with other places of this file.

[sammccall]

Fix quotes

clangd/clients/clangd-vscode/src/extension.ts

  */
 export function activate(context: vscode.ExtensionContext) {
     const clangdPath = getConfig<string>('path');
     const clangdArgs = getConfig<string[]>('arguments');
     const syncFileEvents = getConfig<boolean>('syncFileEvents', true);
 
     const serverOptions: vscodelc.ServerOptions = { command: clangdPath, args: clangdArgs };
 
-    const cppFileExtensions: string[] = ['cpp', 'c', 'cc', 'cxx', 'c++', 'm', 'mm', 'h', 'hh', 'hpp', 'hxx', 'inc'];
-    const cppFileExtensionsPattern = cppFileExtensions.join();
+    const filePattern: string = '**/*.{' +
+      ['cpp', 'c', 'cc', 'cxx', 'c++', 'm', 'mm', 'h', 'hh', 'hpp', 'hxx', 'inc'].join() + '}';
     const clientOptions: vscodelc.LanguageClientOptions = {
         // Register the server for C/C++ files
-        documentSelector: cppFileExtensions,
+        documentSelector: [{scheme: 'file', pattern: filePattern}],
         uriConverters: {
             // FIXME: by default the URI sent over the protocol will be percent encoded (see rfc3986#section-2.1)
             //        the "workaround" below disables temporarily the encoding until decoding
             //        is implemented properly in clangd
             code2Protocol: (uri: vscode.Uri) : string => uri.toString(true),
             protocol2Code: (uri: string) : vscode.Uri => vscode.Uri.parse(uri)
         },
         synchronize: !syncFileEvents ? undefined : {
-            fileEvents: vscode.workspace.createFileSystemWatcher('**/*.{' + cppFileExtensionsPattern + '}')
+            fileEvents: vscode.workspace.createFileSystemWatcher(filePattern)
         }
     };
 
     const clangdClient = new vscodelc.LanguageClient('Clang Language Server', serverOptions, clientOptions);
     console.log('Clang Language Server is now active!');
 
     const disposable = clangdClient.start();
 }