Just configured new windows environment with MSVS 2017 and Qt5.9.1.
While building example project bars
met an error
Project ERROR: Cannot run c
I had a similar case, which was solved by adding the path to cl.exe to the path environment variable:
set path=%path%;%qtdir%\bin;"C:\Program Files (x86)\Microsoft Visual Studio\2017\Community\VC\Tools\MSVC\14.12.25827\bin\Hostx64\x64"
set QMakeSpec=win32-msvc
qmake -tp vc
Maybe another cl.exe is interfering here?