VS tooltip display too verbose when calling overloaded method with wrong parameter types

[smoothdeveloper]

This is an error message improvement suggestion after seeing a picture posted in fsharp.org's slack (user Alanay).

Overload can be little tricky at times, when the overload count is too too high, it would be good to have the VS tooltip show a prettier summary.

Repro steps

Here is a simple case with System.Convert.ToString :

let a = System.Convert.ToString('w',4);;

Actual behavior

Expected behavior

Looking for proposals, here is a first one which would read better:

No overloads match for method 'ToString'.

Argument types given:
  - char
  - int
  
Available overloads:
  - Convert.ToString(value: obj, provider: IFormatProvider)
  - Convert.ToString(value: bool, provider: IFormatProvider)
  - Convert.ToString(value: bool, provider: IFormatProvider)
  - Convert.ToString(value: char, provider: IFormatProvider)
  - Convert.ToString(value: sbyte, provider: IFormatProvider)
  - Convert.ToString(value: byte, provider: IFormatProvider)
  ... exhaustive list we partially see

Workarounds

• reduce overload count
• taller screens

Related information

• environment: Win10/VS2019 16.0.1
• related: Tracking Error reporting improvements #1103, Improve Error Reporting: When implementation is missing necessary overrides, report a list of them #4982

[smoothdeveloper]

Relevant locations:

https://github.com/Microsoft/visualfsharp/blob/c4c1d9cf1097955a71c7cbc328a6b5c672a34bda/src/fsharp/ConstraintSolver.fs#L2379-L2399

https://github.com/Microsoft/visualfsharp/blob/c4c1d9cf1097955a71c7cbc328a6b5c672a34bda/src/fsharp/TypeChecker.fs#L9877-L9944

https://github.com/Microsoft/visualfsharp/blob/c4c1d9cf1097955a71c7cbc328a6b5c672a34bda/src/fsharp/CompileOps.fs#L765-L770

https://github.com/Microsoft/visualfsharp/blob/c4c1d9cf1097955a71c7cbc328a6b5c672a34bda/src/fsharp/FSStrings.resx#L162-L164

[smoothdeveloper]

I'll look at this message (sample from #2503 (comment)):

open System
open System.Threading.Tasks
let makeTask () = new Task<_>(fun () -> 1)
let task = makeTask()
let rt1 = Task.Run(fun () -> task)

Actual:

A unique overload for method 'Run' could not be determined based on type information prior to this program point. A type annotation may be needed. Candidates: Task.Run<'TResult>(function: Func<'TResult>) : Task<'TResult>, Task.Run<'TResult>(function: Func<Task<'TResult>>) : Task<'TResult>

It doesn't look great in VS:

Looking for:

A unique overload for method 'Run' could not be determined based on type information prior to this program point. 

A type annotation may be needed. 

Candidates: 
- Task.Run<'TResult>(function: Func<'TResult>) : Task<'TResult>
- Task.Run<'TResult>(function: Func<Task<'TResult>>) : Task<'TResult>

Please let me know if that makes sense.

I've made some progress in my branch (#6596) for the initial case:

There is work ahead for additional coverage of those messages as it is only lightly covered in fsharpqa tests. (edit: coverage seems appropriate)

More input from users with verbose overload resolution messages in advanced and simple cases would be greatly appreciated.

[smoothdeveloper]

closing this one which got merged in #6596.