Logging: Change arguments of message handler to avoid conversions

Introduce a new QtMessageHandler that takes QString instead of
char *: This avoids converting to local8bit , only to convert it back
to utf16 for Windows.

The old QMessageHandler is kept for a transition period, but will
be removed before Qt 5.0.

Also fix qEmergencyOut (that is called in OOM situations) to not rely
on the default message handler.

Change-Id: Iee0ce5838f97175c98788b847964273dd22d4a37
Reviewed-by: Thiago Macieira <thiago.macieira@intel.com>

1 files changed, 6 insertions, 5 deletions

diff --git a/doc/src/snippets/code/src_corelib_global_qglobal.cpp b/doc/src/snippets/code/src_corelib_global_qglobal.cpp
index 16f6783a52..dc6c3aa616 100644
--- a/doc/src/snippets/code/src_corelib_global_qglobal.cpp
+++ b/doc/src/snippets/code/src_corelib_global_qglobal.cpp
@@ -246,20 +246,21 @@ const TInputType &myMin(const TInputType &value1, const TInputType &value2)
 #include <stdio.h>
 #include <stdlib.h>
 
-void myMessageOutput(QtMsgType type, const QMessageLogContext &context, const char *msg)
+void myMessageOutput(QtMsgType type, const QMessageLogContext &context, const QString &msg)
 {
+    QByteArray localMsg = msg.toLocal8Bit();
     switch (type) {
     case QtDebugMsg:
-        fprintf(stderr, "Debug: %s (%s:%u, %s)\n", msg, context.file, context.line, context.function);
+        fprintf(stderr, "Debug: %s (%s:%u, %s)\n", localMsg.constData(), context.file, context.line, context.function);
         break;
     case QtWarningMsg:
-        fprintf(stderr, "Warning: %s (%s:%u, %s)\n", msg, context.file, context.line, context.function);
+        fprintf(stderr, "Warning: %s (%s:%u, %s)\n", localMsg.constData(), context.file, context.line, context.function);
         break;
     case QtCriticalMsg:
-        fprintf(stderr, "Critical: %s (%s:%u, %s)\n", msg, context.file, context.line, context.function);
+        fprintf(stderr, "Critical: %s (%s:%u, %s)\n", localMsg.constData(), context.file, context.line, context.function);
         break;
     case QtFatalMsg:
-        fprintf(stderr, "Fatal: %s (%s:%u, %s)\n", msg, context.file, context.line, context.function);
+        fprintf(stderr, "Fatal: %s (%s:%u, %s)\n", localMsg.constData(), context.file, context.line, context.function);
         abort();
     }
 }