Failed assertion throws runtime_error; message box moved to GUI main loop try..catch wrapper (#496)

Failed assertions were not properly handled in extant code. We launched a QMessageBox from a thread, which is unsafe according to the Qt docs, and actually failed (it could be repaired by shortening the error message, e.g. by ommitting the file name, but that would be quite fragile a solution).

Now, a failed assertion just throws a std::runtime_error. We don't use qFatal any longer. This allows us to remove the failedAssert function pointer and the QMessageHandler.

If catched inside the GUI, the failed assertion is displayed in the message frame. Otherwise, the exception is catched in the main program, which launches a QMessageBox within a fresh QApplication.

This leaves one specific case uncovered, namely: Failed assertions (and other exceptions) thrown in event handlers but outside specific try blocks.

requested review from @m.svechnikov

added 1 commit

• 20fc397f - corr include

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changed target branch from main to r20.0

1. Exception from ASSERT can (and will) be caught before it reaches the top of the hierarchy, then it is likely to be handled as any other user-produced exception, program will not be terminated.

2. Try, for example, ASSERT(0) in

• ISimulation::runSingleSimulation (inside and outside of std::thread)
• ISimulation::subscribe
• JobWorker::start
• IOFactory::writeDatafield

It will just terminate the program.

added 7 commits

• 20fc397f...71ebb013 - 3 commits from branch r20.0
• d61225bb - Failed assertion throws runtime_error; message box moved to GUI main loop try..catch wrapper
• 3266c782 - corr include
• e1e87906 - use QApplication instance; set return values
• 78632f91 - debugging

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added 5 commits

• 9090b8d7 - GUI JobWorker: extend 'try' coverage; rm special treatment for impossible case of no m_simulation
• 6839c4d2 - Failed assertion throws runtime_error; message box moved to GUI main loop try..catch wrapper
• 9fc767c5 - corr include
• 32db9452 - use QApplication instance; set return values
• b702719c - debugging

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added 8 commits

• b702719c...3fff6fd4 - 4 commits from branch r20.0
• d76cbec6 - Failed assertion throws runtime_error; message box moved to GUI main loop try..catch wrapper
• 6e3201d4 - corr include
• b091a789 - use QApplication instance; set return values
• 79a3dec6 - Failed assert also writes to stderr. Extended try block in main.cpp. MsgBox...

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resolved all threads

changed the description

The mentioned problems [1] and [2] are still in force.

Still not clear to me how assertion exceptions should be separated from the rest of them.

added 1 commit

• ac95af06 - Extend message on failed assertion: 'BUG:', 'Please report ...'

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enabled an automatic merge when the pipeline for ac95af06 succeeds

merged

mentioned in commit ce832e20

mentioned in issue libqcr#7 (closed)