flags--;

src/compiler/commandLineParser.ts

@@ -56,14 +56,6 @@ namespace ts {
             category: Diagnostics.Command_line_Options,
             description: Diagnostics.Stylize_errors_and_messages_using_color_and_context_experimental
         },
-        {
-            name: "diagnosticStyle",
-            type: createMapFromTemplate({
-                auto: DiagnosticStyle.Auto,
-                pretty: DiagnosticStyle.Pretty,
-                simple: DiagnosticStyle.Simple,
-            }),
-        },
         {
             name: "preserveWatchOutput",
             type: "boolean",

src/compiler/tsc.ts

@@ -25,10 +25,10 @@ namespace ts {
     }
 
     function shouldBePretty(options: CompilerOptions) {
-        if ((typeof options.pretty === "undefined" && typeof options.diagnosticStyle === "undefined") || options.diagnosticStyle === DiagnosticStyle.Auto) {
+        if ((typeof options.pretty === "undefined")) {
             return !!sys.writeOutputIsTty && sys.writeOutputIsTty();
         }
-        return options.diagnosticStyle === DiagnosticStyle.Pretty || options.pretty;
+        return options.pretty;
     }
 
     function padLeft(s: string, length: number) {

src/compiler/types.ts

@@ -4194,7 +4194,6 @@ namespace ts {
         /* @internal */ preserveWatchOutput?: boolean;
         project?: string;
         /* @internal */ pretty?: boolean;
-        /* @internal */ diagnosticStyle?: DiagnosticStyle;
         reactNamespace?: string;
         jsxFactory?: string;
         removeComments?: boolean;
@@ -4292,13 +4291,6 @@ namespace ts {
         JSX,
     }
 
-    /* @internal */
-    export const enum DiagnosticStyle {
-        Auto,
-        Pretty,
-        Simple,
-    }
-
     /** Either a parsed command line or a parsed tsconfig.json */
     export interface ParsedCommandLine {
         options: CompilerOptions;