Debug cause of `QObject::connect: invalid null parameter`

skebanga

I am getting an error message on stderr

QObject::connect: invalid null parameter

I do not know where in my code this is coming from.

Is there a way to work out which connection is invalid?

For example, I'd like to configure Qt to abort or throw an exception etc when I attempt to connect with a null parameter.

SGaist

Hi,

Then you should assert the objects you are using in your connection calls.

skebanga

Absolutely agree.

However, there are thousands of QObject::connect calls throughout my codebase.

I do not know where the regression is coming from, and so am looking for help from the framework.

The fact Qt will emit an error message to stderr means it is checking the objects itself - so is there a way to get Qt to fail hard and fail early when given an invalid object?

SGaist

QT_FATAL_WARNINGS to the rescue ! Define this environment variable and your application will crash when a qWarning is used. You can then get the stack trace.

Chris Kawa

Or you could install a message handler and break/crash/log/whatever when the message happens.

skebanga

@SGaist awesome, thank you!

skebanga

@Chris-Kawa equally awesome, thank you too!