Comment on first constructor argument gets removed

[Evangelink]

Issue created from fantomas-online

Code

let automationManager =
    new AnnAutomationManager(
        // WPF or D2D rendering engine must be consistent with the ImageViewerAutomationControl used
        RenderingEngine = new AnnWPFRenderingEngine(),
        // Ensure that the objects are bound to the container
        RestrictDesigners = true,
        // Do not select/edit object after they are drawn
        EditObjectAfterDraw = false,
        EndDrawWhenLostFocus = true)

Result

let automationManager =
    new AnnAutomationManager(
        RenderingEngine = new AnnWPFRenderingEngine(),
        // Ensure that the objects are bound to the container
        RestrictDesigners = true,
        // Do not select/edit object after they are drawn
        EditObjectAfterDraw = false,
        EndDrawWhenLostFocus = true
    )

Problem description

Fantomas seems to remove comment placed on top of the first argument to a constructor call.

Extra information

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

Options

Fantomas Master at 01/05/2021 21:00:18 - d5f4d9f

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]

Hello @Evangelink, thanks for opening a new issue. Much appreciated.
To solve this, the comment (trivia) above SynExpr.Tuple should be printed.
I believe around

fantomas/src/Fantomas/CodePrinter.fs

Line 1924 in d5f4d9f

+> col sepComma args (genShortExpr astContext)

and

fantomas/src/Fantomas/CodePrinter.fs

Line 1933 in d5f4d9f

+> col (sepComma +> sepNln) args (genExprLong astContext)

genTriviaFor SynExpr_Tuple rangeOfTuple could print the trivia.

The rangeOfTuple information is current lost, we should add it to

fantomas/src/Fantomas/SourceParser.fs

Line 734 in d5f4d9f

let (|Tuple|_|) =

and then add it to

fantomas/src/Fantomas/SourceParser.fs

Line 800 in d5f4d9f

let (|AppTuple|_|) =

Would you be interested in submitting a PR?

[Evangelink]

Yes I am :) I will have a look at this during the week-end and might ping for some support if that's ok.

[nojaf]

Yeah sure, sounds good.

[Evangelink]

@nojaf Apologies for the delay, I had a look yesterday and there is something I don't get.

The rangeOfTuple information is current lost, we should add it to

fantomas/src/Fantomas/SourceParser.fs

Line 734 in d5f4d9f

let (|Tuple|_|) =

What I understand is to change:

| SynExpr.Tuple (false, exprs, _, _) -> Some exprs

into:

| SynExpr.Tuple (false, exprs, _, rangeOfTuple) -> Some(exprs, rangeOfTuple)

and to make it surface on the AppTuple active pattern.

But I don't get if I am supposed to add one more object to the return or if I am supposed to do some merge with some of the range.

Current code:

| App (e, [ (Paren (lpr, Tuple args, rpr)) ]) -> Some(e, lpr, args, rpr)

New code:

| App (e, [ (Paren (lpr, Tuple (args, rangeOfTuple), rpr)) ]) -> Some(e, lpr, args, rpr) // What to do with 'rangeOfTuple'

[Evangelink]

Sorry just forgot to post progress, as you can see on the PR I have the start of something but I get the comment set twice before and after the syntax element. Not gonna lie, I haven't understood enough of the code to actually manage to see what's wrong or even how to see what's wrong...