Incorrect Stroustrup indentation with let binding for anonymous record with expression

[josh-degraw]

Sorry to be one of the new voices of issues post v5 🙃

Issue created from fantomas-online

Code

let fooDto =
    {| otherDto with
        TextFilters =
            criteria.Meta.TextFilter
            |> Option.map (fun f -> f.Filters)
            |> Option.map (List.map (sprintf "~%s~"))
            |> Option.toObj
    |}

Result

let fooDto = {| otherDto with
    TextFilters =
        criteria.Meta.TextFilter
        |> Option.map (fun f -> f.Filters)
        |> Option.map (List.map (sprintf "~%s~"))
        |> Option.toObj
|}

Problem description

See above examples for the issue.

Also, if I add a comment or newline to try and preserve formatting, it results in this:

let fooDto =
// Comment
{| otherDto with
    TextFilters =
        criteria.Meta.TextFilter
        |> Option.map (fun f -> f.Filters)
        |> Option.map (List.map (sprintf "~%s~"))
        |> Option.toObj
|}

I think the root cause of this might be related to that of #2501.

Extra information

• The formatted result breaks my code.
• The formatted result gives compiler warnings.
• I or my company would be willing to help fix this.

Options

Fantomas master branch at 2022-09-16T18:11:37Z - 5182588

    { config with
                MultilineBlockBracketsOnSameColumn = true
                ExperimentalStroustrupStyle = true }

_{Did you know that you can ignore files when formatting from fantomas-tool or the FAKE targets by using a .fantomasignore file?}

[nojaf]

Sorry to be one of the new voices of issues post v5 🙃

No worries, someone had to do it 😅.

This one is rather easy to fix I think.
If you look at

fantomas/src/Fantomas.Core/SourceParser.fs

Lines 1773 to 1785 in e1bd963

	let (|StroustrupStyleExpr|_|) (isStroustrupStyleEnabled: bool) (e: SynExpr) =
	if not isStroustrupStyleEnabled then
	None
	else
	match e with
	// { foo with Bar = bar }
	| SynExpr.Record(copyInfo = Some _) -> None
	| SynExpr.Record _
	| SynExpr.AnonRecd _
	// task { ... }
	| SynExpr.App (ExprAtomicFlag.NonAtomic, false, SynExpr.Ident _, SynExpr.ComputationExpr _, _)
	| ArrayOrList _ -> Some e
	| _ -> None

We ignore normal update records as a stroustrup expression: | SynExpr.Record(copyInfo = Some _) -> None.
We should be able to ignore these as well for SynExpr.AnonRecd(copyInfo = Some _). (ref)

Are you up for it?

[josh-degraw]

Are you up for it?
Yeah I'll try and tackle it this weekend if I can!