Splitting list results in code that doesn't compile

[knocte]

Issue created from fantomas-online

Code

namespace NS

module Foo =
    let Bar() =
        [|1|]
type HopPayloadTLV =
    | OutgoingCLTV of int
    | ShortChannelId of int
    member __.ToGenericTLV() =
        let _ = Array.concat[ Foo.Bar(); Foo.Bar() ]
        ()

Result

namespace NS

module Foo =
    let Bar () = [| 1 |]

type HopPayloadTLV =
    | OutgoingCLTV of int
    | ShortChannelId of int
    member __.ToGenericTLV() =
        let _ =
            Array.concat[Foo.Bar()
            Foo.Bar()]

        ()

Problem description

It doesn't compile anymore; gives: Successive arguments should be separated by spaces or tupled, and arguments involving function or method applications should be parenthesized.

Extra information

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

Options

Fantomas master branch at 2022-04-12T06:26:27Z - 7b35c89

Default Fantomas configuration

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

[nojaf]

Duplicate of #2158
Add a space after Array.concat to avoid the new indexer expression.

[abelbraaksma]

@nojaf, unfortunately, adding a space can break code. Consider this:

Working code that fails to format for the same reasons

configureCorsPolicy
    readOnlyDict[$"{hdrKey}:0", "X-MessageID"
                 $"{hdrKey}:1", "Authorization"]

Adding space to prevent the list items to break

This code does not compile anymore, as the compiler thinks the function configureCorsPolicy now has two arguments:

configureCorsPolicy
    readOnlyDict [$"{hdrKey}:0", "X-MessageID"
                  $"{hdrKey}:1", "Authorization"]

This is similar to f dict[a; b] (f has one arg) and f dict [a;b] (f has two args) not being the same.

[nojaf]

Fixed by #2446