1 files changed, 30 insertions, 6 deletions

diff --git a/src/corelib/global/qlogging.cpp b/src/corelib/global/qlogging.cpp
index da26490d18..4a602e4b2b 100644
--- a/src/corelib/global/qlogging.cpp
+++ b/src/corelib/global/qlogging.cpp
@@ -1207,6 +1207,23 @@ static void android_default_message_handler(QtMsgType type,
 static void qDefaultMessageHandler(QtMsgType type, const QMessageLogContext &context,
                                    const QString &buf)
 {
+    // to determine logging destination and marking logging environment variable as deprecated
+    // ### remove when deprecated
+    struct LogDestination {
+        LogDestination(const char *deprecated, bool forceConsole) {
+            const char* replacement = "QT_LOGGING_TO_CONSOLE";
+            bool newEnv = qEnvironmentVariableIsSet(replacement);
+            bool oldEnv = qEnvironmentVariableIsSet(deprecated);
+            if (oldEnv && !newEnv && !forceConsole) {
+                fprintf(stderr, "Warning: Environment variable %s is deprecated, "
+                                "use %s instead.\n", deprecated, replacement);
+                fflush(stderr);
+            }
+            toConsole = newEnv || oldEnv || forceConsole;
+        }
+        bool toConsole;
+    };
+
     QString logMessage = qMessageFormatString(type, context, buf);
 
 #if defined(Q_OS_WIN) && defined(QT_BUILD_CORE_LIB)
@@ -1217,12 +1234,19 @@ static void qDefaultMessageHandler(QtMsgType type, const QMessageLogContext &con
 #endif // Q_OS_WIN
 
 #if defined(QT_USE_SLOG2)
-    slog2_default_handler(type, logMessage.toLocal8Bit().constData());
+    static const bool logToConsole = qEnvironmentVariableIsSet("QT_LOGGING_TO_CONSOLE");
+    if (!logToConsole) {
+        slog2_default_handler(type, logMessage.toLocal8Bit().constData());
+    } else {
+        fprintf(stderr, "%s", logMessage.toLocal8Bit().constData());
+        fflush(stderr);
+    }
 #elif defined(QT_USE_JOURNALD) && !defined(QT_BOOTSTRAPPED)
     // We use isatty to catch the obvious case of someone running something interactively.
-    // We also support an environment variable for Qt Creator use, or more complicated cases like subprocesses.
-    static bool logToConsole = isatty(fileno(stdin)) || !qEnvironmentVariableIsEmpty("QT_NO_JOURNALD_LOG");
-    if (Q_LIKELY(!logToConsole)) {
+    // We also support environment variables for Qt Creator use, or more complicated cases
+    // like subprocesses.
+    static const LogDestination logdest("QT_NO_JOURNALD_LOG", isatty(fileno(stdin)));
+    if (Q_LIKELY(!logdest.toConsole)) {
         // remove trailing \n, systemd appears to want them newline-less
         logMessage.chop(1);
         systemd_default_message_handler(type, context, logMessage);
@@ -1231,8 +1255,8 @@ static void qDefaultMessageHandler(QtMsgType type, const QMessageLogContext &con
         fflush(stderr);
     }
 #elif defined(Q_OS_ANDROID)
-    static bool logToAndroid = qEnvironmentVariableIsEmpty("QT_ANDROID_PLAIN_LOG");
-    if (logToAndroid) {
+    static const LogDestination logdest("QT_ANDROID_PLAIN_LOG", false);
+    if (!logdest.toConsole) {
         android_default_message_handler(type, context, logMessage);
     } else {
         fprintf(stderr, "%s", logMessage.toLocal8Bit().constData());