From bd3e854b31781edfd03f087faf6de21b2bf1b783 Mon Sep 17 00:00:00 2001
From: Daniel Rosenwasser <Daniel.Rosenwasser@microsoft.com>
Date: Fri, 13 Apr 2018 20:51:09 -0700
Subject: [PATCH] Automatically configure tsc output and provide a new
 'diagnosticStyle' option.

---
 src/compiler/commandLineParser.ts |  8 ++++++++
 src/compiler/sys.ts               |  4 ++++
 src/compiler/tsc.ts               | 11 +++++++++--
 src/compiler/types.ts             |  6 ++++--
 4 files changed, 25 insertions(+), 4 deletions(-)

diff --git a/src/compiler/commandLineParser.ts b/src/compiler/commandLineParser.ts
index 470bd111492..252ea9e8df0 100644
--- a/src/compiler/commandLineParser.ts
+++ b/src/compiler/commandLineParser.ts
@@ -56,6 +56,14 @@ 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",
diff --git a/src/compiler/sys.ts b/src/compiler/sys.ts
index c37315a2e56..2a4616732dd 100644
--- a/src/compiler/sys.ts
+++ b/src/compiler/sys.ts
@@ -428,6 +428,7 @@ namespace ts {
         newLine: string;
         useCaseSensitiveFileNames: boolean;
         write(s: string): void;
+        writeOutputIsTty?(): boolean;
         readFile(path: string, encoding?: string): string | undefined;
         getFileSize?(path: string): number;
         writeFile(path: string, data: string, writeByteOrderMark?: boolean): void;
@@ -561,6 +562,9 @@ namespace ts {
                 write(s: string): void {
                     process.stdout.write(s);
                 },
+                writeOutputIsTty() {
+                    return process.stdout.isTTY;
+                },
                 readFile,
                 writeFile,
                 watchFile: getWatchFile(),
diff --git a/src/compiler/tsc.ts b/src/compiler/tsc.ts
index f16ca98c93d..5012b73e98a 100644
--- a/src/compiler/tsc.ts
+++ b/src/compiler/tsc.ts
@@ -19,11 +19,18 @@ namespace ts {
 
     let reportDiagnostic = createDiagnosticReporter(sys);
     function updateReportDiagnostic(options: CompilerOptions) {
-        if (options.pretty) {
+        if (shouldBePretty(options)) {
             reportDiagnostic = createDiagnosticReporter(sys, /*pretty*/ true);
         }
     }
 
+    function shouldBePretty(options: CompilerOptions) {
+        if ((typeof options.pretty === "undefined" && typeof options.diagnosticStyle === "undefined") || options.diagnosticStyle === DiagnosticStyle.Auto) {
+            return !!sys.writeOutputIsTty && sys.writeOutputIsTty();
+    }
+        return options.diagnosticStyle === DiagnosticStyle.Pretty || options.pretty;
+    }
+
     function padLeft(s: string, length: number) {
         while (s.length < length) {
             s = " " + s;
@@ -159,7 +166,7 @@ namespace ts {
     }
 
     function createWatchStatusReporter(options: CompilerOptions) {
-        return ts.createWatchStatusReporter(sys, !!options.pretty);
+        return ts.createWatchStatusReporter(sys, shouldBePretty(options));
     }
 
     function createWatchOfConfigFile(configParseResult: ParsedCommandLine, optionsToExtend: CompilerOptions) {
diff --git a/src/compiler/types.ts b/src/compiler/types.ts
index 987d403e7cd..802c175b573 100644
--- a/src/compiler/types.ts
+++ b/src/compiler/types.ts
@@ -4193,7 +4193,8 @@ namespace ts {
         preserveSymlinks?: boolean;
         /* @internal */ preserveWatchOutput?: boolean;
         project?: string;
-        /* @internal */ pretty?: DiagnosticStyle;
+        /* @internal */ pretty?: boolean;
+        /* @internal */ diagnosticStyle?: DiagnosticStyle;
         reactNamespace?: string;
         jsxFactory?: string;
         removeComments?: boolean;
@@ -4293,8 +4294,9 @@ namespace ts {
 
     /* @internal */
     export const enum DiagnosticStyle {
-        Simple,
+        Auto,
         Pretty,
+        Simple,
     }
 
     /** Either a parsed command line or a parsed tsconfig.json */