2 files changed, 29 insertions, 6 deletions
diff --git a/src/corelib/global/qglobal.cpp b/src/corelib/global/qglobal.cpp
index 6dba733fb4..871810e5a3 100644
--- a/src/corelib/global/qglobal.cpp
+++ b/src/corelib/global/qglobal.cpp
@@ -4419,8 +4419,11 @@ bool QInternal::activateCallbacks(Callback cb, void **parameters)
     stderr. Under Windows, the message is sent to the debugger.
     On QNX the message is sent to slogger2. This
     function does nothing if \c QT_NO_WARNING_OUTPUT was defined
-    during compilation; it exits if the environment variable \c
-    QT_FATAL_WARNINGS is not empty.
+    during compilation; it exits if at the nth warning corresponding to the
+    counter in environment variable \c QT_FATAL_WARNINGS. That is, if the
+    environment variable contains the value 1, it will exit on the 1st message;
+    if it contains the value 10, it will exit on the 10th message. Any
+    non-numeric value is equivalent to 1.
 
     This function takes a format string and a list of arguments,
     similar to the C printf() function. The format should be a Latin-1
diff --git a/src/corelib/global/qlogging.cpp b/src/corelib/global/qlogging.cpp
index 6573e0a53e..927c1bb76b 100644
--- a/src/corelib/global/qlogging.cpp
+++ b/src/corelib/global/qlogging.cpp
@@ -153,19 +153,39 @@ Q_NORETURN
 static void qt_message_fatal(QtMsgType, const QMessageLogContext &context, const QString &message);
 static void qt_message_print(QtMsgType, const QMessageLogContext &context, const QString &message);
 
+static int checked_var_value(const char *varname)
+{
+    // qEnvironmentVariableIntValue returns 0 on both parsing failure and on
+    // empty, but we need to distinguish between the two for backwards
+    // compatibility reasons.
+    QByteArray str = qgetenv(varname);
+    if (str.isEmpty())
+        return 0;
+
+    bool ok;
+    int value = str.toInt(&ok, 0);
+    return ok ? value : 1;
+}
+
 static bool isFatal(QtMsgType msgType)
 {
     if (msgType == QtFatalMsg)
         return true;
 
     if (msgType == QtCriticalMsg) {
-        static bool fatalCriticals = !qEnvironmentVariableIsEmpty("QT_FATAL_CRITICALS");
-        return fatalCriticals;
+        static QAtomicInt fatalCriticals = checked_var_value("QT_FATAL_CRITICALS");
+
+        // it's fatal if the current value is exactly 1,
+        // otherwise decrement if it's non-zero
+        return fatalCriticals.load() && fatalCriticals.fetchAndAddRelaxed(-1) == 1;
     }
 
     if (msgType == QtWarningMsg || msgType == QtCriticalMsg) {
-        static bool fatalWarnings = !qEnvironmentVariableIsEmpty("QT_FATAL_WARNINGS");
-        return fatalWarnings;
+        static QAtomicInt fatalWarnings = checked_var_value("QT_FATAL_WARNINGS");
+
+        // it's fatal if the current value is exactly 1,
+        // otherwise decrement if it's non-zero
+        return fatalWarnings.load() && fatalWarnings.fetchAndAddRelaxed(-1) == 1;
     }
 
     return false;