cmMessenger: Color messages to terminal by type

Fixes: #16183

Help/release/dev/message-color.rst

@@ -0,0 +1,4 @@
+message-color
+-------------
+
+* Messages printed to a terminal now may be colored by message type.

Source/cmMessageMetadata.h

@@ -2,7 +2,10 @@
    file Copyright.txt or https://cmake.org/licensing for details.  */
 #pragma once
 
+#include "cmsys/Terminal.h"
+
 struct cmMessageMetadata
 {
   const char* title = nullptr;
+  int desiredColor = cmsysTerminal_Color_Normal;
 };

Source/cmMessenger.cxx

@@ -13,6 +13,8 @@
 
 #include <sstream>
 
+#include "cmsys/Terminal.h"
+
 MessageType cmMessenger::ConvertMessageType(MessageType t) const
 {
   bool warningsAsErrors;
@@ -85,6 +87,21 @@ static bool printMessagePreamble(MessageType t, std::ostream& msg)
   return true;
 }
 
+static int getMessageColor(MessageType t)
+{
+  switch (t) {
+    case MessageType::INTERNAL_ERROR:
+    case MessageType::FATAL_ERROR:
+    case MessageType::AUTHOR_ERROR:
+      return cmsysTerminal_Color_ForegroundRed;
+    case MessageType::AUTHOR_WARNING:
+    case MessageType::WARNING:
+      return cmsysTerminal_Color_ForegroundYellow;
+    default:
+      return cmsysTerminal_Color_Normal;
+  }
+}
+
 void printMessageText(std::ostream& msg, std::string const& text)
 {
   msg << ":\n";
@@ -122,6 +139,7 @@ void displayMessage(MessageType t, std::ostringstream& msg)
 
   // Output the message.
   cmMessageMetadata md;
+  md.desiredColor = getMessageColor(t);
   if (t == MessageType::FATAL_ERROR || t == MessageType::INTERNAL_ERROR ||
       t == MessageType::DEPRECATION_ERROR || t == MessageType::AUTHOR_ERROR) {
     cmSystemTools::SetErrorOccured();

Source/cmakemain.cxx

@@ -6,6 +6,7 @@
 #include <algorithm>
 #include <cassert>
 #include <climits>
+#include <cstdio>
 #include <cstring>
 #include <iostream>
 #include <sstream>
@@ -23,6 +24,7 @@
 #include "cmDocumentationEntry.h" // IWYU pragma: keep
 #include "cmGlobalGenerator.h"
 #include "cmMakefile.h"
+#include "cmMessageMetadata.h"
 #include "cmProperty.h"
 #include "cmState.h"
 #include "cmStateTypes.h"
@@ -37,8 +39,7 @@
 #endif
 
 #include "cmsys/Encoding.hxx"
-
-struct cmMessageMetadata;
+#include "cmsys/Terminal.h"
 
 namespace {
 #ifndef CMAKE_BOOTSTRAP
@@ -150,9 +151,11 @@ std::string cmakemainGetStack(cmake* cm)
 }
 
 void cmakemainMessageCallback(const std::string& m,
-                              const cmMessageMetadata& /* unused */, cmake* cm)
+                              const cmMessageMetadata& md, cmake* cm)
 {
-  std::cerr << m << cmakemainGetStack(cm) << std::endl;
+  cmsysTerminal_cfprintf(md.desiredColor, stderr, "%s", m.c_str());
+  fflush(stderr); // stderr is buffered in some cases.
+  std::cerr << cmakemainGetStack(cm) << "\n";
 }
 
 void cmakemainProgressCallback(const std::string& m, float prog, cmake* cm)