I switched from Qt 4.7.3 / VC++ Express 2008 to Qt 4.8.0 / VC++ Express 2010.
When starting qmake to create a .vcxproj file from a .pro file I first get a warning that there would be multiple VC++ installations but none of them would be in PATH.
To solve this I tried to 1. specify QMAKESPEC environment variable; 2. Adding the same make spec using qmake's command line options; 3. Start qmake from Qt shell; 4. Start Qt from VC++ 2010's bin folder to PATH manually. But the result was always the same: qmake didn't complain about finding no VC++ in PATH anymore but about finding multiple VC++ installations in path! Since qmake always fell back to the oldest VC++ Express installation I uninstalled VC++ Express 2008 as a workaround.
This is a nasty behaviour and should be improved.
Now qmake uses the VC++ Express 2010 installation as desired (since there is no other fallback) but I still get senseless warnings for every qmake call:
WARNING: Generator: MSVC.NET: Found more than one version of Visual Studio in your path! Fallback to lowest version (MSVC.NET 2010 (10.0), MSVC.NET 20
10 Express Edition (10.0), MSVC.NET 2010 (10.0) in path, MSVC.NET 2010 Express Edition (10.0) in path)
This is stupid. qmake seems to recoginze the single VC++ 2010 Express 2010 installation as two VC++ installations. This is definitly wrong. On my PC there is VC# Express 2010 and VC++ Express 2010 installed. But there has never been an Visual Studio 2010 installation.