C# to F# go to definition navigates to metadata, and not the source code

[oleksandr-bilyk]

Every year we have to buy Rider because Rider allows to navigate from C# code to F# method definition.
We had big expectations that VS2022 will support such a basic feature but not.
Our team decided to use F# in solution where we have many C# and F# projects calling each other.
This small feature is very important for future use of F# in our solutions.

[vzarytovskii]

@tmat do you have any insights on how should we approach it?

My guess is that we theoretically can provide either IGoToDefinitionSymbolService , IFindDefinitionService or ISymbolMappingService, which can provide needed info to Roslyn, however it is tied to ISymbol, not sure what is the correct approach here.

[smoothdeveloper]

@oleksandr-bilyk please consider appending your experience in this discussion: dotnet/csharplang#6412 (comment)

it is about "C#-adjacent tooling experience" from C# Language Design Meeting notes discussions.

The reverse navigation works (Go To Definition on C# member from F# code reaches), which I think came at some point in VS 2019.

[tmat]

@CyrusNajmabadi IIRC LSP should be able to handle this, correct?

[vzarytovskii]

dotnet/roslyn#64010 is in, will experiment with it next week

[kerams]

The reverse navigation works (Go To Definition on C# member from F# code reaches),

You say that, but it stopped working for me with yesterday's VS preview update :).

[vzarytovskii]

The reverse navigation works (Go To Definition on C# member from F# code reaches),

You say that, but it stopped working for me with yesterday's VS preview update :).

Works for me:

Do you have any specific example?

[kerams]

BCL/external dependency metadata navigation. I'm pressing F12 on this to no avail (it used to work). Perhaps it's a different use case.

[vzarytovskii]

BCL/external dependency metadata navigation. I'm pressing F12 on this to no avail (it used to work). Perhaps it's a different use case.

Yep, doesn't work for me for Newtonsoft.Json.

[vzarytovskii]

I hopefully can fix it in one batch with C#->F# navigation.

[smoothdeveloper]

@kerams / @vzarytovskii I noticed in some F# editor "go to definition" use cases, it will generate F# signature (of C# code).

IMO, generating F# signatures is relevant, only if those cases don't resolve:

• project reference, with the source file
• assembly reference with pdb pointing to source file
• sourcelink

AND if, the assembly referenced is compiled with F#.

If it is not the case, it is probably better to do what the C# editor would do.

@vzarytovskii and @CyrusNajmabadi, thanks for giving a shot at the C# -> F# code navigation, this is going to help a lot.

[vzarytovskii]

IMO, generating F# signatures is relevant, only if those cases don't resolve:

• project reference, with the source file

I think, if we know that we have source, we will navigate to it.

• assembly reference with pdb pointing to source file
• sourcelink

Not sure about these. Will try to remember and look at it. When I navigate to "WriteLine" source code now, it brings me to the source (not sure whether via sourcelink ok pdbs).

[dsyme]

@vzarytovskii I removed the VS label - trying to keep to one most-specific Area label per issue, unless it really is across multiple areas

[dsyme]

Closing #3497 as a duplicate of this more recent one. There is interesting information there on prototype attempts to address this

[vzarytovskii]

Note: new API with assembly name included: dotnet/roslyn#64475
Will make changes in the WIP branch, once back next week.