Prevent 'qmake -query' from bringing up modal message dialog on startup

Temporarily set the ErrorMode so that no Windows error message box will
show up in case qmake fails to run (e.g. because of missing .dll's).
The error mode will automatically be inherited by child processes.

This fixes an issue that actually became virulent by another bug fix
( cbb053068c ).

Task-number: QTCREATORBUG-11962
Change-Id: I5baccf52baee46f3d45b69ea0a13d77e4e113fbd
Reviewed-by: Friedemann Kleint <Friedemann.Kleint@digia.com>
Reviewed-by: Tobias Hunger <tobias.hunger@digia.com>

src/libs/utils/winutils.cpp

@@ -172,4 +172,22 @@ QTCREATOR_UTILS_EXPORT bool is64BitWindowsBinary(const QString &binaryIn)
 #endif
 }
 
+WindowsCrashDialogBlocker::WindowsCrashDialogBlocker()
+#ifdef Q_OS_WIN
+    : silenceErrorMode(SEM_NOGPFAULTERRORBOX | SEM_NOOPENFILEERRORBOX | SEM_FAILCRITICALERRORS),
+    originalErrorMode(SetErrorMode(silenceErrorMode))
+#endif
+{
+}
+
+WindowsCrashDialogBlocker::~WindowsCrashDialogBlocker()
+{
+#ifdef Q_OS_WIN
+    unsigned int errorMode = SetErrorMode(originalErrorMode);
+    // someone else messed with the error mode in between? Better not touch ...
+    QTC_ASSERT(errorMode == silenceErrorMode, SetErrorMode(errorMode));
+#endif
+}
+
+
 } // namespace Utils

src/libs/utils/winutils.h

@@ -49,6 +49,23 @@ QTCREATOR_UTILS_EXPORT bool is64BitWindowsSystem();
 // Check for a 64bit binary.
 QTCREATOR_UTILS_EXPORT bool is64BitWindowsBinary(const QString &binary);
 
+//
+// RAII class to temporarily prevent windows crash messages from popping up using the
+// application-global (!) error mode.
+//
+// Useful primarily for QProcess launching, since the setting will be inherited.
+//
+class QTCREATOR_UTILS_EXPORT WindowsCrashDialogBlocker {
+public:
+    WindowsCrashDialogBlocker();
+    ~WindowsCrashDialogBlocker();
+#ifdef Q_OS_WIN
+private:
+    const unsigned int silenceErrorMode;
+    const unsigned int originalErrorMode;
+#endif // Q_OS_WIN
+};
+
 } // namespace Utils
 
 #endif // WINUTILS_H

src/plugins/qtsupport/baseqtversion.cpp

@@ -48,6 +48,7 @@
 #include <utils/qtcassert.h>
 #include <utils/runextensions.h>
 #include <utils/synchronousprocess.h>
+#include <utils/winutils.h>
 
 #include <QDir>
 #include <QUrl>
@@ -1206,6 +1207,9 @@ static QByteArray runQmakeQuery(const FileName &binary, const Environment &env,
 
     const int timeOutMS = 30000; // Might be slow on some machines.
 
+    // Prevent e.g. qmake 4.x on MinGW to show annoying errors about missing dll's.
+    WindowsCrashDialogBlocker crashDialogBlocker;
+
     QProcess process;
     process.setEnvironment(env.toStringList());
     process.start(binary.toString(), QStringList(QLatin1String("-query")), QIODevice::ReadOnly);