Bug report from fantomas-ui - creates invalid F# for string handling operations

[cgravill]

Issue created from fantomas-ui

This is a minimal reproduction of an issue with string handling code in a more complex code base. Fantomas forced .PadLeft(9) onto a new line, then when re-run got the positioning off which leads to compilation failures.

Code

let x =
    [| 1..2 |]
    |> Array.mapi (fun _ _ ->
        let num =
            ""
                .PadLeft(9)
        num)

Error

let x =
    [| 1..2 |]
    |> Array.mapi (fun _ _ ->
           let num = ""
                   .PadLeft(9)
           num)

Options

Fantomas 2.9.1

Name	Value
IndentSpaceNum	4
PageWidth	80
PreserveEndOfLine	false
SemicolonAtEndOfLine	false
SpaceBeforeArgument	true
SpaceBeforeColon	true
SpaceAfterComma	true
SpaceAfterSemicolon	true
IndentOnTryWith	false
ReorderOpenDeclaration	false
SpaceAroundDelimiter	true
StrictMode	false

Most of our code works really well with Fantomas, thanks!

Variations also lead to exceptions when run via FAKE:

Script reported an error:
-> BuildFailedException: Target 'FormatCode' failed.
-> One or more errors occurred. (Exception of type 'Fantomas.FakeHelpers+CodeFormatException' was thrown.)
-> CodeFormatException: Exception of type 'Fantomas.FakeHelpers+CodeFormatException' was thrown.