Merge pull request #10950 from heejaechang/changedefault

turn on v2 diagnostic engine as default

src/Workspaces/Core/Portable/Diagnostics/InternalDiagnosticsOptions.cs

@@ -9,7 +9,7 @@ internal static class InternalDiagnosticsOptions
         public const string OptionName = "InternalDiagnosticsOptions";
 
         public static readonly Option<bool> BlueSquiggleForBuildDiagnostic = new Option<bool>(OptionName, "Blue Squiggle For Build Diagnostic", defaultValue: false);
-        public static readonly Option<bool> UseDiagnosticEngineV2 = new Option<bool>(OptionName, "Use Diagnostic Engine V2", defaultValue: false);
+        public static readonly Option<bool> UseDiagnosticEngineV2 = new Option<bool>(OptionName, "Use Diagnostic Engine V2", defaultValue: true);
         public static readonly Option<bool> CompilationEndCodeFix = new Option<bool>(OptionName, "Enable Compilation End Code Fix", defaultValue: true);
         public static readonly Option<bool> UseCompilationEndCodeFixHeuristic = new Option<bool>(OptionName, "Enable Compilation End Code Fix With Heuristic", defaultValue: true);
         public static readonly Option<bool> BuildErrorIsTheGod = new Option<bool>(OptionName, "Make build errors to take over everything", defaultValue: false);