Logging: introduce QInternalMessageLogContext to hold current context

QMessageLogContext is a primitive type that may be extended in the
future with more fields (it has been at version 2 since commit
6d166c88220ee09821b65fb2b711fa77a5312971, though that did not extend the
struct's size). This introduces a QInternalMessageLogContext which is
used in before all our calls to qt_message_output().

Currently there's no difference and no way to tell that the internal
version is used.

Change-Id: I01ec3c774d9943adb903fffd17b7d5abc0052207
Reviewed-by: Giuseppe D'Angelo <giuseppe.dangelo@kdab.com>

src/corelib/global/qlogging.cpp

@@ -382,9 +382,10 @@ static void qt_message(QtMsgType msgType, const QMessageLogContext &context, con
 */
 void QMessageLogger::debug(const char *msg, ...) const
 {
+    QInternalMessageLogContext ctxt(context);
     va_list ap;
     va_start(ap, msg); // use variable arg list
-    qt_message(QtDebugMsg, context, msg, ap);
+    qt_message(QtDebugMsg, ctxt, msg, ap);
     va_end(ap);
 }
 
@@ -397,9 +398,10 @@ void QMessageLogger::debug(const char *msg, ...) const
 */
 void QMessageLogger::info(const char *msg, ...) const
 {
+    QInternalMessageLogContext ctxt(context);
     va_list ap;
     va_start(ap, msg); // use variable arg list
-    qt_message(QtInfoMsg, context, msg, ap);
+    qt_message(QtInfoMsg, ctxt, msg, ap);
     va_end(ap);
 }
 
@@ -429,9 +431,7 @@ void QMessageLogger::debug(const QLoggingCategory &cat, const char *msg, ...) co
     if (!cat.isDebugEnabled())
         return;
 
-    QMessageLogContext ctxt;
+    QInternalMessageLogContext ctxt(context, cat());
-    ctxt.copyContextFrom(context);
-    ctxt.category = cat.categoryName();
 
     va_list ap;
     va_start(ap, msg); // use variable arg list
@@ -453,9 +453,7 @@ void QMessageLogger::debug(QMessageLogger::CategoryFunction catFunc,
     if (!cat.isDebugEnabled())
         return;
 
-    QMessageLogContext ctxt;
+    QInternalMessageLogContext ctxt(context, cat());
-    ctxt.copyContextFrom(context);
-    ctxt.category = cat.categoryName();
 
     va_list ap;
     va_start(ap, msg); // use variable arg list
@@ -534,9 +532,7 @@ void QMessageLogger::info(const QLoggingCategory &cat, const char *msg, ...) con
     if (!cat.isInfoEnabled())
         return;
 
-    QMessageLogContext ctxt;
+    QInternalMessageLogContext ctxt(context, cat());
-    ctxt.copyContextFrom(context);
-    ctxt.category = cat.categoryName();
 
     va_list ap;
     va_start(ap, msg); // use variable arg list
@@ -558,9 +554,7 @@ void QMessageLogger::info(QMessageLogger::CategoryFunction catFunc,
     if (!cat.isInfoEnabled())
         return;
 
-    QMessageLogContext ctxt;
+    QInternalMessageLogContext ctxt(context, cat());
-    ctxt.copyContextFrom(context);
-    ctxt.category = cat.categoryName();
 
     va_list ap;
     va_start(ap, msg); // use variable arg list
@@ -624,9 +618,10 @@ QDebug QMessageLogger::info(QMessageLogger::CategoryFunction catFunc) const
 */
 void QMessageLogger::warning(const char *msg, ...) const
 {
+    QInternalMessageLogContext ctxt(context);
     va_list ap;
     va_start(ap, msg); // use variable arg list
-    qt_message(QtWarningMsg, context, msg, ap);
+    qt_message(QtWarningMsg, ctxt, msg, ap);
     va_end(ap);
 }
 
@@ -642,9 +637,7 @@ void QMessageLogger::warning(const QLoggingCategory &cat, const char *msg, ...)
     if (!cat.isWarningEnabled())
         return;
 
-    QMessageLogContext ctxt;
+    QInternalMessageLogContext ctxt(context, cat());
-    ctxt.copyContextFrom(context);
-    ctxt.category = cat.categoryName();
 
     va_list ap;
     va_start(ap, msg); // use variable arg list
@@ -666,9 +659,7 @@ void QMessageLogger::warning(QMessageLogger::CategoryFunction catFunc,
     if (!cat.isWarningEnabled())
         return;
 
-    QMessageLogContext ctxt;
+    QInternalMessageLogContext ctxt(context, cat());
-    ctxt.copyContextFrom(context);
-    ctxt.category = cat.categoryName();
 
     va_list ap;
     va_start(ap, msg); // use variable arg list
@@ -729,9 +720,10 @@ QDebug QMessageLogger::warning(QMessageLogger::CategoryFunction catFunc) const
 */
 void QMessageLogger::critical(const char *msg, ...) const
 {
+    QInternalMessageLogContext ctxt(context);
     va_list ap;
     va_start(ap, msg); // use variable arg list
-    qt_message(QtCriticalMsg, context, msg, ap);
+    qt_message(QtCriticalMsg, ctxt, msg, ap);
     va_end(ap);
 }
 
@@ -747,9 +739,7 @@ void QMessageLogger::critical(const QLoggingCategory &cat, const char *msg, ...)
     if (!cat.isCriticalEnabled())
         return;
 
-    QMessageLogContext ctxt;
+    QInternalMessageLogContext ctxt(context, cat());
-    ctxt.copyContextFrom(context);
-    ctxt.category = cat.categoryName();
 
     va_list ap;
     va_start(ap, msg); // use variable arg list
@@ -771,9 +761,7 @@ void QMessageLogger::critical(QMessageLogger::CategoryFunction catFunc,
     if (!cat.isCriticalEnabled())
         return;
 
-    QMessageLogContext ctxt;
+    QInternalMessageLogContext ctxt(context, cat());
-    ctxt.copyContextFrom(context);
-    ctxt.category = cat.categoryName();
 
     va_list ap;
     va_start(ap, msg); // use variable arg list
@@ -836,9 +824,7 @@ QDebug QMessageLogger::critical(QMessageLogger::CategoryFunction catFunc) const
 */
 void QMessageLogger::fatal(const QLoggingCategory &cat, const char *msg, ...) const noexcept
 {
-    QMessageLogContext ctxt;
+    QInternalMessageLogContext ctxt(context, cat());
-    ctxt.copyContextFrom(context);
-    ctxt.category = cat.categoryName();
 
     va_list ap;
     va_start(ap, msg); // use variable arg list
@@ -862,9 +848,7 @@ void QMessageLogger::fatal(QMessageLogger::CategoryFunction catFunc,
 {
     const QLoggingCategory &cat = (*catFunc)();
 
-    QMessageLogContext ctxt;
+    QInternalMessageLogContext ctxt(context, cat());
-    ctxt.copyContextFrom(context);
-    ctxt.category = cat.categoryName();
 
     va_list ap;
     va_start(ap, msg); // use variable arg list
@@ -884,9 +868,10 @@ void QMessageLogger::fatal(QMessageLogger::CategoryFunction catFunc,
 */
 void QMessageLogger::fatal(const char *msg, ...) const noexcept
 {
+    QInternalMessageLogContext ctxt(context);
     va_list ap;
     va_start(ap, msg); // use variable arg list
-    QT_TERMINATE_ON_EXCEPTION(qt_message(QtFatalMsg, context, msg, ap));
+    QT_TERMINATE_ON_EXCEPTION(qt_message(QtFatalMsg, ctxt, msg, ap));
     va_end(ap);
 
 #ifndef Q_CC_MSVC_ONLY
@@ -2057,9 +2042,10 @@ static void qt_message_fatal(QtMsgType, const QMessageLogContext &context, Strin
 */
 void qt_message_output(QtMsgType msgType, const QMessageLogContext &context, const QString &message)
 {
-    qt_message_print(msgType, context, message);
+    QInternalMessageLogContext ctx(context);
+    qt_message_print(msgType, ctx, message);
     if (isFatal(msgType))
-        qt_message_fatal(msgType, context, message);
+        qt_message_fatal(msgType, ctx, message);
 }
 
 void qErrnoWarning(const char *msg, ...)
@@ -2074,7 +2060,7 @@ void qErrnoWarning(const char *msg, ...)
     va_end(ap);
 
     buf += " ("_L1 + error_string + u')';
-    QMessageLogContext context;
+    QInternalMessageLogContext context{QMessageLogContext()};
     qt_message_output(QtWarningMsg, context, buf);
 }
 
@@ -2088,7 +2074,7 @@ void qErrnoWarning(int code, const char *msg, ...)
     va_end(ap);
 
     buf += " ("_L1 + qt_error_string(code) + u')';
-    QMessageLogContext context;
+    QInternalMessageLogContext context{QMessageLogContext()};
     qt_message_output(QtWarningMsg, context, buf);
 }
 

src/corelib/global/qlogging.h

@@ -37,15 +37,17 @@ enum QtMsgType {
 #endif
 };
 
+class QInternalMessageLogContext;
 class QMessageLogContext
 {
     Q_DISABLE_COPY(QMessageLogContext)
 public:
+    static constexpr int CurrentVersion = 2;
     constexpr QMessageLogContext() noexcept = default;
     constexpr QMessageLogContext(const char *fileName, int lineNumber, const char *functionName, const char *categoryName) noexcept
         : line(lineNumber), file(fileName), function(functionName), category(categoryName) {}
 
-    int version = 2;
+    int version = CurrentVersion;
     int line = 0;
     const char *file = nullptr;
     const char *function = nullptr;
@@ -54,8 +56,8 @@ public:
 private:
     QMessageLogContext &copyContextFrom(const QMessageLogContext &logContext) noexcept;
 
+    friend class QInternalMessageLogContext;
     friend class QMessageLogger;
-    friend class QDebug;
 };
 
 class QLoggingCategory;

src/corelib/global/qlogging_p.h

@@ -16,6 +16,8 @@
 //
 
 #include <QtCore/private/qglobal_p.h>
+#include "qlogging.h"
+#include "qloggingcategory.h"
 
 QT_BEGIN_NAMESPACE
 
@@ -25,6 +27,22 @@ Q_CORE_EXPORT bool shouldLogToStderr();
 
 }
 
+class QInternalMessageLogContext : public QMessageLogContext
+{
+public:
+    QInternalMessageLogContext(const QMessageLogContext &logContext)
+    {
+        copyContextFrom(logContext);
+    }
+    QInternalMessageLogContext(const QMessageLogContext &logContext,
+                               const QLoggingCategory &categoryOverride)
+        : QInternalMessageLogContext(logContext)
+    {
+        category = categoryOverride.categoryName();
+    }
+
+};
+
 QT_END_NAMESPACE
 
 #endif // QLOGGING_P_H

src/corelib/io/qdebug.cpp

@@ -5,6 +5,7 @@
 #include "qdebug.h"
 #include "private/qdebug_p.h"
 #include "qmetaobject.h"
+#include <private/qlogging_p.h>
 #include <private/qtextstream_p.h>
 #include <private/qtools_p.h>
 
@@ -150,15 +151,15 @@ QByteArray QtDebugUtils::toPrintable(const char *data, qint64 len, qsizetype max
 
     Flushes any pending data to be written and destroys the debug stream.
 */
-// Has been defined in the header / inlined before Qt 5.4
 QDebug::~QDebug()
 {
     if (stream && !--stream->ref) {
         if (stream->space && stream->buffer.endsWith(u' '))
             stream->buffer.chop(1);
         if (stream->message_output) {
+            QInternalMessageLogContext ctxt(stream->context);
             qt_message_output(stream->type,
-                              stream->context,
+                              ctxt,
                               stream->buffer);
         }
         delete stream;