Provide FSharpEntity.EnclosingEntity

[vasily-kirichenko]

In dotnet/fsharp#3803 I do the following:

• get an open declaration (which is now available as a property in FSharpFileCheckResults and presented as FSharpEntity [])
• check if any of symbols defined in each of the modules / namespaces above is used in the scope this particular open declaration is open

Currently I call FSharpEntity.MembersFunctionsAndValues for each namespace/module and it's the bottleneck - on middle sized files the analyzer takes several seconds to finish, on TypeChecker.fs it takes ~2 minutes, which is too slow.

So I'm trying to use different approach: get enclosing entity of each symbol uses and check if it corresponds to a module/ns from open declarations, which eliminates calling MembersFunctionsAndValues entirely. Unfortunately, only values, functions and members have EnclosingEntity (that is, modules for my purpose). I need this property for FSharpEntity too.

This approach is indeed a lot faster. Ignoring FSharpEntity and checking only vals and functions via EnclosingEntity processes TypeChecker.fs in 4 seconds, smaller files in tens of milliseconds.

I tried to add this here vasily-kirichenko/visualfsharp@39173f6, but I've completely lost.

EnclosingEntity should contain proper value for both F# and IL types and modules and namespaces (None - for root namespaces).

@dsyme could you please suggest a proper way to add this functionality?

[dsyme]

Yes, it's not there because of a bit of a flaw in the TAST. I've put it on my TODO list to try to root this problem out. We will need it for other reasons too

[vasily-kirichenko]

Thanks a lot!

[dsyme]

@auduchinok I managed to improve the performance of unused opens dotnet/fsharp#4497 without implementing this. I'd still like to get it implemented though, it would make things simpler and faster

[auduchinok]

@dsyme I've checked the new unused opens implementation and it's indeed works much faster on an average solution/files, however getting children of something like JetBrains.Util still looks to take longer than a small file type check. The good news is tweaking unused imports to use the new DeclaredEntity made performance great on this file.

I'm looking into opening a PR with usage of DeclaredEntity, but will try to fix dotnet/fsharp#4658 first.