Semantic checking doesn't work in Qt Creator 2.5 - ide

Question

I don't get an error for this obviously erroneous code sample. Instead, qt creator mark var as unused variable. Is it possible to fix this strange behavior? I want semantic checking working.
Update:
I've been talking about on the fly semantic checking. Most IDE's analyse code as you type, and highlite errors. Qt Creator seemd to do some code analisis on the fly (because syntax highliting shows differently types, virtual functions and other things), but it doesn't hightlte errors at all.

Answer 1

The code model used by Qt Creator is pretty good but is not based on a complete abstract syntax tree for each compilation unit. Some information about it is provided in this Qt blog post:
http://blog.qt.digia.com/2011/10/19/qt-creator-and-clang/
AFAIK, the current code model allows Qt Creator to do semantic highlighting, refactoring, displaying type hierarchies etc. but does not allow a complete on-the fly check for potential compile errors (like yours). Since the syntax of your code is correct, Qt Creator does not show an error.

Answer 2

Very strange behavior. I tried to compile such code:
#include <iostream>
using namespace std;
int main()
{
UndefinedType val;
cout<<"Test"<<endl;
return 0;
}
On My Qt 4.8.1, 4.8.3 with MinGW on Windows7, in QtCreator 2.5.2, but in every case got error:
main.cpp: In function 'int main()':
main.cpp:7:5: error: 'UndefinedType' was not declared in this scope
main.cpp:7:19: error: expected ';' before 'val'
Please, provide more information about your build environment.