Enable new language features for F# 5.0

[KevinRansom]

KevinRansom commented 20 minutes ago
We have done final reviews for these features and are confident they are ready for F# 5.0

    LanguageFeature.OpenStaticClasses, languageVersion50
    LanguageFeature.PackageManagement, languageVersion50
    LanguageFeature.WitnessPassing, languageVersion50
    LanguageFeature.InterfacesWithMultipleGenericInstantiation, languageVersion50
    LanguageFeature.NameOf, languageVersion50

We will address remaining issues and updates as bug fixes.
The InterpolatedStrings and Slicing features will be reviewed before RTM in order to consider inclusion in F# 5.0

Kevin

[TIHan]

This looks fine, but let's wait till we get all the nameof and open type updates in first.

[smoothdeveloper]

@KevinRansom, regarding LanguageFeature.PackageManagement, I've given a shot to most recent dotnet core and VS2019 previews, and was able to make it work with paket implementation, although I've not yet looked into details about the number of calls being made (which came in discussion in a PR from you about how the lines are commited for evaluation).

There is still one thing I'm not able to get working, which is integrating the similar usage through FSharp.Compiler.Service APIs, I was looking at getting a typed AST and compiled assembly from in-memory code buffer.

After some testing there, ParseAndCheckFileInProject and CompileToDynamicAssembly don't seem to activate the path with dependency manager, although for the first call, I'm passing /langversion:preview as an option.

Is there anything pending on this area or pointers that would help me figure out what I'm missing?

Also, one thing which seems missing in FCS is ability to pass compiler flags or "project options" to the CompileToDynamicAssembly, but maybe I'm overlooking the proper usage.

[KevinRansom]

@smoothdeveloper , if you can put together a small repro, I will take a look. However, what used to work should still work. I haven't really done anything that should break existing code paths.