Add main function wrapper to catch exceptions and avoid annoying error popup on windows

[res2k]

Description

This adds a wrapper around main() functions to deal with unhandled exceptions by printing a "fatal" log message and exiting.
The motivation is the behavior of unhandled exceptions on MSVC. There, such an exception simply terminates the program, but the exception message is not output anywhere! This can make troubleshooting very confusing, as the log of a tool gives no indication of a problem.

Features list

Not really a feature.

Implementation remarks

Wrapper is "opt-in" by including system/main.hpp.
The header defines a macro main so the main() function in the source appears like the real one even though it's wrapped. It's also convenient.

[fabiencastan]

Thanks for the contribution. I fully agree with the need!

Few remarks regarding the implementation:
1/ I would prefer to find a solution without having to create a define on "main". You can easily have a library with a member variable named "int main;" or something else.
We could just manually rename "main" by "aliceVision_main" in all main_*.cpp files so it is explicit and if the main.hpp is not included, the compilation will fail.

2/ I would keep main.hpp as a header only file and I would also remove the intermediate aliceVision_main_wrapper, as we can just put the try/catch in the real main.

What do think?

[res2k]

Hi,
I've made the changes you requested.

[fabiencastan]

I would suggest a more explicit comment, like:

// Implementation of the unique main entry point.
// This method will call aliceVision_main and catch the exceptions to
// log the error message and avoid seg fault on exception on windows.

[res2k]

Ok, I expanded the comment.

[fabiencastan]

It would be good to apply it on all main_*.cpp and not only software/pipeline.

[res2k]

It would be good to apply it on all main_*.cpp and not only software/pipeline.

Yes. I would have done that as a follow-up PR, but I can add it to this one as well.