Support multi-project analysis

[fsharp]

Support multi-project analysis

One concern is that this approach still won't work for mixed-language solutions.

Presumably in XS and Roslynified-VS the idea is to draw cross-project metadata from the symbol APIs provided by the IDE. But that's a big change for FCS.

I suppose enabling single -language cross-project in FCS is still the best thing to do (particularly for F# projects that have a corresponding unit test project, for example)

[7sharp9]

In XS this would be done be creating a larger NRefactory bridge from the data FCS returns. Building up from compilation units etc.

[7sharp9]

It would be nice if symbol requests for different project were aggregated inside FCS, so that a symbol retrieved from project a could be searched for in project b.

Right, but we'd also need the other way around - take NRefactory information and feed it into the F# compiler (a bit like a type provider, actually, and the same codepaths could possibly be used). But its a big change to do this, and in any case cross-language metadata is not yet readily available in VS AFAIK.

Adding F#-to-F# project references to FCS is much more tractable though.

[7sharp9]

As far as XS is concerned NRefactory its supposed to be a language neutral way of storing all that information, csc is used to fill NRefactory with the C# symbol information.

I think the will be a certain gap in services once you try to bridge different IDE's like XS and VS due the the mechanisms involved internally etc.

[7sharp9]

Im not sure if spending time building it is worth it. Cant the symbol finder simply be called once for each project?

[dungpa]

One step at a time. I think enabling F# cross-project analysis is already useful in a lot of use cases.

[7sharp9]

Yes, but what Im saying is, can't you do that with the current FCS, get the symbols from each project and search them.

[dungpa]

It's doable with current FCS but delegating multi-project analysis to FCS could probably give better performance and incrementality. And it's an IDE-agnostic process which benefits all the clients :).

I understand the concern about mismatch between different IDEs in handling cross-language solutions though.

@7sharp9 It's only doable with the current service if compiled DLLs exist for the cross-project references. This also adds an extra level of (largely hidden) state for the user.

Some initial support for cross-project references has been added to FCS in 0.0.30.

See “Analyzing multiple projects” in http://fsharp.github.io/FSharp.Compiler.Service/project.html