[Driver] Automatic -color-diagnostics flag is added *before* -Xfrontend

Author: broadwaylamb

lib/Driver/ToolChains.cpp

@@ -2,7 +2,7 @@
 //
 // This source file is part of the Swift.org open source project
 //
-// Copyright (c) 2014 - 2018 Apple Inc. and the Swift project authors
+// Copyright (c) 2014 - 2019 Apple Inc. and the Swift project authors
 // Licensed under Apache License v2.0 with Runtime Library Exception
 //
 // See https://swift.org/LICENSE.txt for license information
@@ -172,6 +172,10 @@ static void addCommonFrontendArgs(const ToolChain &TC, const OutputInfo &OI,
     arguments.push_back(inputArgs.MakeArgString(OI.SDKPath));
   }
 
+  if (llvm::sys::Process::StandardErrHasColors()) {
+    arguments.push_back("-color-diagnostics");
+  }
+
   inputArgs.AddAllArgs(arguments, options::OPT_I);
   inputArgs.AddAllArgs(arguments, options::OPT_F, options::OPT_Fsystem);
 
@@ -262,11 +266,6 @@ static void addCommonFrontendArgs(const ToolChain &TC, const OutputInfo &OI,
   // Pass through any subsystem flags.
   inputArgs.AddAllArgs(arguments, options::OPT_Xllvm);
   inputArgs.AddAllArgs(arguments, options::OPT_Xcc);
-
-  if (!inputArgs.hasArg(options::OPT_color_diagnostics,
-                        options::OPT_no_color_diagnostics) &&
-      llvm::sys::Process::StandardErrHasColors())
-    arguments.push_back("-color-diagnostics");
 }
 
 static void addRuntimeLibraryFlags(const OutputInfo &OI,

lib/Frontend/CompilerInvocation.cpp

@@ -2,7 +2,7 @@
 //
 // This source file is part of the Swift.org open source project
 //
-// Copyright (c) 2014 - 2018 Apple Inc. and the Swift project authors
+// Copyright (c) 2014 - 2019 Apple Inc. and the Swift project authors
 // Licensed under Apache License v2.0 with Runtime Library Exception
 //
 // See https://swift.org/LICENSE.txt for license information
@@ -26,6 +26,7 @@
 #include "llvm/Support/FileSystem.h"
 #include "llvm/Support/LineIterator.h"
 #include "llvm/Support/Path.h"
+#include "llvm/Support/Process.h"
 
 using namespace swift;
 using namespace llvm::opt;
@@ -659,8 +660,10 @@ static bool ParseDiagnosticArgs(DiagnosticOptions &Opts, ArgList &Args,
   Opts.SkipDiagnosticPasses |= Args.hasArg(OPT_disable_diagnostic_passes);
   Opts.ShowDiagnosticsAfterFatalError |=
     Args.hasArg(OPT_show_diagnostics_after_fatal);
-  Opts.UseColor |= Args.hasFlag(OPT_color_diagnostics,
-                                OPT_no_color_diagnostics);
+  Opts.UseColor |=
+      Args.hasFlag(OPT_color_diagnostics,
+                   OPT_no_color_diagnostics,
+                   /*Default=*/llvm::sys::Process::StandardErrHasColors());
   Opts.FixitCodeForAllDiagnostics |= Args.hasArg(OPT_fixit_all);
   Opts.SuppressWarnings |= Args.hasArg(OPT_suppress_warnings);
   Opts.WarningsAsErrors |= Args.hasArg(OPT_warnings_as_errors);

lib/Frontend/PrintingDiagnosticConsumer.cpp

@@ -2,7 +2,7 @@
 //
 // This source file is part of the Swift.org open source project
 //
-// Copyright (c) 2014 - 2017 Apple Inc. and the Swift project authors
+// Copyright (c) 2014 - 2019 Apple Inc. and the Swift project authors
 // Licensed under Apache License v2.0 with Runtime Library Exception
 //
 // See https://swift.org/LICENSE.txt for license information
@@ -112,9 +112,9 @@ void PrintingDiagnosticConsumer::handleDiagnostic(
     llvm::raw_svector_ostream Out(Text);
     DiagnosticEngine::formatDiagnosticText(Out, FormatString, FormatArgs);
   }
-  
+
   auto Msg = SM.GetMessage(Loc, SMKind, Text, Ranges, FixIts);
-  rawSM.PrintMessage(out, Msg);
+  rawSM.PrintMessage(out, Msg, ForceColors);
 }
 
 llvm::SMDiagnostic