VS Go to definition from C# to F#

[vzarytovskii]

Note

Please note, that this is a a simple and naive implementation for navigation to F# symbol from C# project (Fixes#13882).

It does not yet support parameters-based navigation for methods, it will select just first implementation in case if there are overloads. This to be fixed in the next version.

Not entirely sure how to properly test it just yet. If you have better idea, please do share.

It selects target project based on assembly name, and searches symbol based on its DocumentCommentId, which has the following formats:

T: prefix for types

• T:N.X.Nested - type
• T:N.X.D - delegate

M: prefix is for methods

• M:N.X.#ctor - constructor
• M:N.X.#ctor(System.Int32) - constructor with one parameter
• M:N.X.f - method with unit parameter
• M:N.X.bb(System.String,System.Int32@) - method with two parameters
• M:N.X.gg(System.Int16[],System.Int32[0:,0:]) - method with two parameters, 1d and 2d array
• M:N.X.op_Addition(N.X,N.X) - operator
• M:N.X.op_Explicit(N.X)~System.Int32 - operator with return type
• M:N.GenericMethod.WithNestedType``1(N.GenericType{``0}.NestedType) - generic type with one parameter
• M:N.GenericMethod.WithIntOfNestedType``1(N.GenericType{System.Int32}.NestedType) - generic type with one parameter
• M:N.X.N#IX{N#KVP{System#String,System#Int32}}#IXA(N.KVP{System.String,System.Int32}) - explicit interface implementation

E: prefix for events

• E:N.X.d.

F: prefix for fields

• F:N.X.q - field

P: prefix for properties

• P:N.X.prop - property with getter and setter

Supported scenarios:

• Simple functions
• Events, fields and properties
• Constructors
• Types
• Generic functions
• Overloaded methods, based on type parameters.
• Operators
• Records
• Discriminated unions

The following are out of scope for this 1st implementation:

• Overloaded methods/ctors based on method parameters.
  • Right now it will navigate to the 1st it finds.

Next steps:

• In next iteration, we utilize IStreamingFindUsagesPresenter when we can't distinguish which exact method/function to go to.
• We should utilize/port Roslyn's DocumentCommentId parser to fetch exact types for parameters and use them for lookup.

[vzarytovskii]

This is ready for the first iteration, please see comments in the OP, regarding tests and what's supported.

[0101]

We could probably do this in parallel.

[vzarytovskii]

This is just a fool-proof, we expect it always be only a single project, parallel then will give you a bunch of overhead

[0101]

Right, didn't notice where it's coming from. Is it even theoretically possible there will be multiple projects with the same assembly name? Because maybe you could replace filter with tryFind and it would be a bit simpler.

[vzarytovskii]

Is it even theoretically possible there will be multiple projects with the same assembly name?

Very unlikely, I have never seen it before.

Because maybe you could replace filter with tryFind and it would be a bit simpler.

I'll see how it looks with option

[0101]

With option it could look something like this (After also adding DocCommentId.EntityPath):

letproject= workspace.CurrentSolution.Projects |> Seq.tryFind (fun p -> p.IsFSharp && p.AssemblyName = assemblyName)letlocations= project
|> Option.map (fun project ->let!checker,_,_,options = project.GetFSharpCompilationOptionsAsync(cancellationToken)let!result= checker.ParseAndCheckProject(options)letentity= path.EntityPath |> result.AssemblySignature.FindEntityByPath
match path with| DocCommentId.Member ({ MemberOrValName = memberOrVal; GenericParameters = genericParametersCount }, memberType)->
entity |> tryFindVal memberOrVal documentationCommentId memberType genericParametersCount
| DocCommentId.Field { MemberOrValName = memberOrVal }->
entity |> tryFindFieldByName memberOrVal
| DocCommentId.Type _-> Seq.singleton entity.DeclarationLocation
| DocCommentId.None -> Seq.empty |> Seq.map (fun m ->(m, project)))|> Option.defaultValue Seq.empty

A bit easier to see what's going on with arrows only going in one direction :)

[vzarytovskii]

probably should replace with Option.map/iter or something

[psfinaki]

Annoying question - any idea/chance to test this?

[vzarytovskii]

Annoying question - any idea/chance to test this?

No, I've asked the same question in the first paragraph

[KevinRansom]

Looks pretty good, no tests yet though. (That's rich coming from me :-))

[vzarytovskii]

Looks pretty good, no tests yet though. (That's rich coming from me :-))

Yeah, that's the question - I'm not yet entirely sure how to do that.

[vzarytovskii]

Ok, this is ready, I failed (gave up really) to add proper tests in headless VS, but added to the important part - parser for doccomment id.
I suggest we merge it as is and test it, otherwise PR will go stale for longer time.

[0101]

With option it could look something like this (After also adding DocCommentId.EntityPath):

letproject= workspace.CurrentSolution.Projects |> Seq.tryFind (fun p -> p.IsFSharp && p.AssemblyName = assemblyName)letlocations= project
|> Option.map (fun project ->let!checker,_,_,options = project.GetFSharpCompilationOptionsAsync(cancellationToken)let!result= checker.ParseAndCheckProject(options)letentity= path.EntityPath |> result.AssemblySignature.FindEntityByPath
match path with| DocCommentId.Member ({ MemberOrValName = memberOrVal; GenericParameters = genericParametersCount }, memberType)->
entity |> tryFindVal memberOrVal documentationCommentId memberType genericParametersCount
| DocCommentId.Field { MemberOrValName = memberOrVal }->
entity |> tryFindFieldByName memberOrVal
| DocCommentId.Type _-> Seq.singleton entity.DeclarationLocation
| DocCommentId.None -> Seq.empty |> Seq.map (fun m ->(m, project)))|> Option.defaultValue Seq.empty

A bit easier to see what's going on with arrows only going in one direction :)