Error when property has same name as DU case

[edgarfgp]

Description

Fixes #16646

Checklist

• Test cases added

• Performance benchmarks added in case of performance changes

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[edgarfgp]

Seems like I have some unrelated tests failing.
Failed TryGetRecentCheckResultsForFile called with snapshot returns cached result after ParseAndCheckFile(True) [240 ms] Error Message: System.Exception : no results from TryGetRecentCheckResultsForFile
cc @vzarytovskii FYI

[vzarytovskii]

Seems like we I have some unrelated tests failing. Failed TryGetRecentCheckResultsForFile called with snapshot returns cached result after ParseAndCheckFile(True) [240 ms] Error Message: System.Exception : no results from TryGetRecentCheckResultsForFile cc @vzarytovskii FYI

I have seen this one today as well. It's a transparent compiler tests, I will disable it and create an issue for re-enabling.

[vzarytovskii]

#16766

[edgarfgp]

@psfinaki This now raises an error message if you accessing to a member that has the same name as the union case. reusing FS0023

(Error 23, Line 17, Col 51, Line 17, Col 56, "The member 'IdA' can not be defined because the name 'IdA' clashes with the union case 'IdA' in this type or module")

I propose we update the error message so it can be used in both cases ie

• member is defined
• member is used

Avoiding having to create another error number and message. Maybe

• The member 'IdA' can not be used because 'IdA' clashes with the union case 'IdA' in this type or module

• The name 'IdA' can not be used because 'IdA' clashes with the union case 'IdA' in this type or module

• The member 'IdA' can not be defined or accessed because the name 'IdA' clashes with the union case 'IdA' in this type or module

cc @vzarytovskii

[psfinaki]

Hmm but why not having both errors here? As in,

type MyId =
    | IdA of int
    | IdB of string

    member this.IdA =
        match this with
        | IdA x -> Some x
        | _ -> None
 
let onlyIdA (ids: MyId list) = ids |> List.choose _.IdA

...would produce both
FS0023 The member 'IdA' can not be defined because the name 'IdA' clashes with the union case 'IdA' in this type or module and
FS0812 The syntax 'expr.id' may only be used with record labels, properties and fields,
as if they were independent (which they kind of are)?

[edgarfgp]

The issue is that the existing logic uses error(Error(..)) which prevents the analysis to continue so even if we try to add both they would cancel each other. Ideally it would be good to change to use errorR but will require rewriting of pat of the analysis. The best we can do for now is to reuse FS0023

[psfinaki]

I mean I probably misunderstand something here - why cannot/shouldn't we fix the error recovery in this case instead?

[edgarfgp]

It is not that we can't. But it will required updating/splitting the upstream analysis to make it work as error returns exn -> 'T and errorR returns exn -> unit.

[edgarfgp]

But if you feel adventurous we can maybe pair on this, maybe in an AmplifyingF# session :)

[edgarfgp]

Context: This is the relevant piece of code that will needs updating https://github.com/dotnet/fsharp/blob/f29ce0aef9b70bfef03ef7466ec823e449bb864b/src/Compiler/Checking/CheckExpressions.fs#L9270C5-L9270C21

[psfinaki]

Well I just believe this can be an opportunity to fix the underlying issue rather than patch the symptome. But that's just my opinion 👀

Otherwise, "The member 'IdA' can not be defined or accessed" is something I would pick out of the options.

[edgarfgp]

Well at the very least I would give a try and report some progress :)

[edgarfgp]

@psfinaki Im revisiting this here #17088