Adds support for easyloggingpp to log WARNING, ERROR, and FATAL to standard error

CHANGELOG.md

@@ -1,5 +1,8 @@
 # Change Log
 
+## [9.97.1] - 30-10-2022
+- Adds support for easyloggingpp to log WARNING, ERROR, and FATAL to standard error. this befaviour can be reverted to old behaviour by defining `#define ELPP_CUSTOM_CERR std::cout`. this provides the the ability for CHECK macros and application abortion messages to be written to standard error instead of standard output. this is required in order for DEATH_TEST macro's in google test to match against easyloggingpp output, for example, `ASSERT_DEATH({CHECK_EQ(1, 2) << "error: value_a is not equal to value_b"; }, ".*value_a is not equal to value_b");`
+
 ## [9.97.0] - 25-12-2020
 ### Features
  * Support for QNX OS

README.md

@@ -529,6 +529,7 @@ Some of logging options can be set by macros, this is a thoughtful decision, for
 | `ELPP_DISABLE_LOG_FILE_FROM_ARG`        | Forcefully disables ability to set default log file from command-line arguments                                                                    |
 | `ELPP_WINSOCK2`        | On windows system force to use `winsock2.h` instead of `winsock.h` when `WIN32_LEAN_AND_MEAN` is defined                                                                    |
 | `ELPP_CUSTOM_COUT` (advanced)     | Resolves to a value e.g, `#define ELPP_CUSTOM_COUT qDebug()` or `#define ELPP_CUSTOM_COUT std::cerr`. This will use the value for standard output (instead of using `std::cout`|
+| `ELPP_CUSTOM_CERR` (advanced)     | Resolves to a value e.g, `#define ELPP_CUSTOM_CERR qDebug()` or `#define ELPP_CUSTOM_CERR std::cout`. This will use the value for standard output (instead of using `std::cerr`|
 | `ELPP_CUSTOM_COUT_LINE` (advanced) | Used with `ELPP_CUSTOM_COUT` to define how to write a log line with custom cout. e.g, `#define ELPP_CUSTOM_COUT_LINE(msg) QString::fromStdString(msg).trimmed()` |
 | `ELPP_NO_CHECK_MACROS`             | Do not define the *CHECK* macros                                                                                                                  |
 | `ELPP_NO_DEBUG_MACROS`             | Do not define the *DEBUG* macros                                                                                                                  |

src/easylogging++.cc

@@ -2243,7 +2243,8 @@ void DefaultLogDispatchCallback::dispatch(base::type::string_t&& logLine) {
     if (m_data->logMessage()->logger()->m_typedConfigurations->toStandardOutput(m_data->logMessage()->level())) {
       if (ELPP->hasFlag(LoggingFlag::ColoredTerminalOutput))
         m_data->logMessage()->logger()->logBuilder()->convertToColoredOutput(&logLine, m_data->logMessage()->level());
-      ELPP_COUT << ELPP_COUT_LINE(logLine);
+      if (m_data->logMessage()->level() == Level::Warning || m_data->logMessage()->level() == Level::Error || m_data->logMessage()->level() == Level::Fatal) ELPP_CERR << ELPP_COUT_LINE(logLine);
+      else ELPP_COUT << ELPP_COUT_LINE(logLine);
     }
   }
 #if defined(ELPP_SYSLOG)
@@ -2284,10 +2285,11 @@ void AsyncLogDispatchCallback::handle(const LogDispatchData* data) {
       && data->logMessage()->logger()->typedConfigurations()->toStandardOutput(data->logMessage()->level())) {
     if (ELPP->hasFlag(LoggingFlag::ColoredTerminalOutput))
       data->logMessage()->logger()->logBuilder()->convertToColoredOutput(&logLine, data->logMessage()->level());
-    ELPP_COUT << ELPP_COUT_LINE(logLine);
+    if (data->logMessage()->level() == Level::Warning || data->logMessage()->level() == Level::Error || data->logMessage()->level() == Level::Fatal) ELPP_CERR << ELPP_COUT_LINE(logLine);
+    else ELPP_COUT << ELPP_COUT_LINE(logLine);
   }
   // Save resources and only queue if we want to write to file otherwise just ignore handler
-  if (data->logMessage()->logger()->typedConfigurations()->toFile(data->logMessage()->level())) {
+  if (data->logMessage()->logger()->typedConfigurations()->toFile(level)) {
     ELPP->asyncLogQueue()->push(AsyncLogItem(*(data->logMessage()), *data, logLine));
   }
 }

src/easylogging++.h

@@ -508,6 +508,7 @@ namespace type {
 #undef ELPP_LITERAL
 #undef ELPP_STRLEN
 #undef ELPP_COUT
+#undef ELPP_CERR
 #if defined(ELPP_UNICODE)
 #  define ELPP_LITERAL(txt) L##txt
 #  define ELPP_STRLEN wcslen
@@ -516,6 +517,11 @@ namespace type {
 #  else
 #    define ELPP_COUT std::wcout
 #  endif  // defined ELPP_CUSTOM_COUT
+#  if defined ELPP_CUSTOM_CERR
+#    define ELPP_CERR ELPP_CUSTOM_CERR
+#  else
+#    define ELPP_CERR std::wcerr
+#  endif  // defined ELPP_CUSTOM_CERR
 typedef wchar_t char_t;
 typedef std::wstring string_t;
 typedef std::wstringstream stringstream_t;
@@ -529,6 +535,11 @@ typedef std::wostream ostream_t;
 #  else
 #    define ELPP_COUT std::cout
 #  endif  // defined ELPP_CUSTOM_COUT
+#  if defined ELPP_CUSTOM_CERR
+#    define ELPP_CERR ELPP_CUSTOM_CERR
+#  else
+#    define ELPP_CERR std::cerr
+#  endif  // defined ELPP_CUSTOM_CERR
 typedef char char_t;
 typedef std::string string_t;
 typedef std::stringstream stringstream_t;