fsharp Fix analysis of conjunctive patterns for exhaustiveness

The analysis of conjunctive patterns pat & pat has problems.

https://github.com/dotnet/fsharp/issues/1281
https://github.com/dotnet/fsharp/issues/3294

This is a first look at fixing this - it will need some care and careful review but let's first see if this causes any problems.

Apr 20 '22 06:04 dsyme

Improving the pattern matching in conjunction with AP would be really nice . I have hit some of above limitation, making hard to grasp for a newcomer

Jul 22 '22 19:07 edgarfgp

This probably needs a bunch of tests, from the linked issues.

Aug 24 '22 13:08 vzarytovskii

/azp run

Sep 05 '22 16:09 vzarytovskii

Azure Pipelines successfully started running 2 pipeline(s).

Sep 05 '22 16:09 azure-pipelines[bot]

This probably needs a bunch of tests, from the linked issues.

I did add some unites locally and it seems that only the second issue on the list is fixed. The first one still show a warning "This rule will never be matched"

Happy to raise a PR to Don's fork with the unit tests :)

Sep 19 '22 12:09 edgarfgp

@edgarfgp Thank you so much for checking! I've checked too and it seems both are fixed - with the first issue, two warnings were being generated - one for incomplete matching, and one for "never matched". The second is correct to emit, the first is not.

I've added testing for both test cases.

Sep 22 '22 14:09 dsyme

@vzarytovskii This is ready

Sep 22 '22 14:09 dsyme

@dsyme Thanks for fixing this . I use AP and this will make the experience much better

Sep 23 '22 12:09 edgarfgp

@vzarytovskii This seems to be ready and the CI timed out. Would be awesome to have this in :)

Sep 27 '22 10:09 edgarfgp