Thank you for such a detailed comment. Makes sense. I need to think how to proceed. Will ping you when I figure something out.

I think clang-format is yelling at places where formatting should not be applied, so I'm gonna ignore that.

Thank you for review! Implemented the changes

Well, unfortunately I'm unable to reproduce the failed builds. Everything passes for me locally. @lattner or @klimek, or someone who you think is a good candidate to review this code - could you please try to test it?
Could you please assist me how to proceed with this patch?

Sorry for the delay of fixing failed builds. Full builds and tests take some time. I'm working on it, promise.
The code itself won't change much, so I think it can be reviewed. Or at least the idea can be judged if it's something desired to have in clang. @lattner or @klimek could you please recommend someone to ask for review?

Great, I can see some builds have failed. Will do my best to fix that tomorrow.

Hi again, since I don't have commit rights, could you please merge this patch into the project sources? Thanks in advance.

@rsmith Of course. Not sure what's better: to submit one patch per case or submit all of them in one patch (didn't deal much with them, not sure how big will the change be)?

@Rakete1111 Any more comments?

Friendly ping (:

Not sure if you guys are still reviewing this. Do you have any more thoughts? If no, what should I do to move further with the patch?

@Rakete1111 or anyone else, any more comments? (:

Added missing semicolon.

Added test cases for the code.

Thanks for the advice. Should I update a new diff with -U99999?

@Rakete1111 Thank you for the comments. You're perfectly right, there was an issue in my code. I've fixed it and also E1 and E2 will be sequenced only in C++ >= 17.

Thanks for pointing that out. You're probably right, these two calls are self-explanatory.

@djasper You're probably right. Thanks anyway for your time (: