--diff on workspace files opens the workspace instead of diff-ing them (fix microsoft#149731) (microsoft#155011)

Author: bpasero

src/vs/platform/windows/electron-main/windowsMainService.ts

@@ -785,7 +785,12 @@ export class WindowsMainService extends Disposable implements IWindowsMainServic
 
 	private doExtractPathsFromCLI(cli: NativeParsedArgs): IPath[] {
 		const pathsToOpen: IPathToOpen[] = [];
-		const pathResolveOptions: IPathResolveOptions = { ignoreFileNotFound: true, gotoLineMode: cli.goto, remoteAuthority: cli.remote || undefined, forceOpenWorkspaceAsFile: false };
+		const pathResolveOptions: IPathResolveOptions = {
+			ignoreFileNotFound: true,
+			gotoLineMode: cli.goto,
+			remoteAuthority: cli.remote || undefined,
+			forceOpenWorkspaceAsFile: cli.diff && cli._.length === 2 // special case diff mode to force open workspace as file (https://github.com/microsoft/vscode/issues/149731)
+		};
 
 		// folder uris
 		const folderUris = cli['folder-uri'];