'IntelliSense on Functions' tooltip does not appear when in parentheses related to other construct

[JordanMarr]

I have found a few scenarios where the new functions parameter tooltip does not work using VS 16.9 preview 3:

• Computation Expressions
• Lambda Expressions

Repro steps

Computation Expressions

The new preview IntelliSense context tooltip does not appear within computation expressions.
I've verified this against the following CEs:

• async
• asyncResult
• Fable.GroupingPanel

Lambda Expressions

It also does not appear when placed within the body of a lambda expression.
This works:

let add n1 n2 = n1 + n2
let sum = add 1 2 // The new tooltip correctly appears

This does not work:

let lst = [1; 2; 3]
let mapped = 
    lst |> List.map (fun n ->
        let sum = add 1 2 // New tooltip does not appear; instead, shows old tooltip
        n.ToString()
    )

Expected behavior

Should always show the new function parameter preview that shows all parameters.

Actual behavior

Sometimes reverts to the old preview that only shows the current parameter.

• Windows 10
• Tested on .NET Core 3.1 and .NET Standard projects
• Visual Studio Professional 16.9 Preview 3

[cartermp]

Computation expressions is covered here: #10835

Should be in the 16.9 full release, unsure about a specific preview

Within parens in a lambda is an interesting issue that I anticipated would arise but wasn't sure of the impact. Should be fun to take a look

[cartermp]

Just to add a screenshot, this is what's going on:

This is because TryRangeOfFunctionOrMethodBeingApplied has a bug where it picks List.map rather than sum.

Additionally, TryIdentOfPipelineContainingPosAndNumArgsApplied is making an assumption causing the number of reported curried arguments to be incorrect.

[cartermp]

Marking this here for now, a quirk I noticed when editing code int he compiler. I can't say if it's related yet:

[cartermp]

Using #10957 to track the issue I noticed and another.

[cartermp]

Thanks for the report. The issue as-reported is fixed here: #10954

We're nearing a code freeze for VS 16.9 so I'll see if I can cherry pick the fix into the release. If not, then this would be in the 16.10 previews.

There are a few other quirks tracked in #10957 - if you notice additional issues, please file new ones or comment on that thread. I can move things around/create issues as needed.

[cartermp]

Hmm, I'm actually going to re-open this because the "old" tooltip will still trigger for me. I noticed this happening again and it's less common, but still triggers. It's actually due to something else. Consider the following:

type C() =
    member _.M(x) = ()


let c = C()
c.M(sqrt)// <<- caret is after 't'!

When you hit the space key, signature help for M is given instead of for sqrt. What's happening is that the syntax tree APIs are working from the outside in and noticing that M(... is considered valid for a tooltip and then shows that. We really need to dive further in and only show the most relevant one