qmake cannot run g++: $$system() not working under Windows 7

[Ashpool]

@SGaist no, the kit appears to have been configured properly. The bundled gcc, g++ and gdb were nicely detected out-of-the-box.

[SGaist]

Did you try to close Qt Creator, nuke the build folder, the .pro.user file and then reconfigure your project ?

[Ashpool]

@SGaist no, but I did create new helloworld projects several times. Also, as far as I can tell, the problem occurs before any project-specific files and settings get involved

[SGaist]

Do you still currently have several versions of MinGW ?

If so, can you remove the others ?

[Ashpool]

@SGaist I will try that as soon as I get to my workstation. However what I did try was nuking the QTCreator's folder in AppData/Roaming, which caused all settings to reset, which included forgetting those manually added MinGW compilers. The bundled ones were detected again, and the kits were shown as if configured correctly

[Ashpool]

@SGaist I removed all versions of MinGW except the one that came with Qt. My kit page in Qt Creator's preferences now has only one auto-detected kit "Desktop Qt 5.11.3 MinGW 32bit" which shows no errors or warnings. It's configured to use the MinGW binaries from Qt\Tools\mingw530_32\bin\. Upon creating a new Qt Widgets project the issue persists. There's also this message before I even try to build the project:

Project ERROR: failed to parse default search paths from compiler output

and any Qt-related symbols and includes in the code editor are highlighted as unknown. It was there all along, I just didn't mention it. I believe it is caused by the same issue I described in the original post.

I should also mention that I did not compile Qt manually or make any modifications to it. I used the default online installer to install 5.12.2 and 5.13.0, and I used an offline installer to install 5.11.3.

[Ashpool]

I used the ProcessMonitor application from the Windows SysInternals Suite to try to determine where things go wrong. It looks like qmake.exe doesn't even try to run g++. If it did, — unsuccessfully — the log would contain a line which would look like
qmake.exe — QueryOpen — D:\some\path\which\doesnt\exist\g++.exe — NAME NOT FOUND
This, as you can see from the screenshot, is not the case.

[Ashpool]

This is how my kits and compilers pages in preferences are looking currently. Sorry for the Russian captions.

Kits:

Compilers:

[SGaist]

All looks pretty good...

I suppose you can also successfully start g++ from the command line if you use the full path to the compiler ?

[Ashpool]

@SGaist yes, indeed I can. I also added D:\Qt\Tools\mingw530_32\bin, the path containing it, to the PATH environment variable, just for good measure.

[SGaist]

I am currently running out of ideas...

As a last resort, did you try a full Qt uninstallation/computer reboot/Qt installation ?

[Makis]

@SGaist this happens to me and is very frustrating. The only solution i have is to create a new w10 account and install a new Qt there. I have no issues on other 2 w10 machines.