Removes type annotation without brackets

[artemiipatov]

Issue created from fantomas-online

Code

let clReducedValues, clFirstActualKeys, clSecondActualKeys: ClArray<'a> * ClArray<int> * ClArray<int> =
    reduce processor DeviceOnly resultLength clOffsets clFirstKeys clSecondKeys clValues

Result

let clReducedValues, clFirstActualKeys, clSecondActualKeys =
    reduce processor DeviceOnly resultLength clOffsets clFirstKeys clSecondKeys clValues

Problem description

Fantomas removes type annotation without brackets. But when brackets are placed around names, annotations are not removed.

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.
• I would like a release if this problem is solved.

Options

Fantomas main branch at 1/1/1990

Default Fantomas configuration

_{Did you know that you can ignore files when formatting by using a .fantomasignore file?
PS: It's unlikely that someone else will solve your specific issue, as it's something that you have a personal stake in.}

[nojaf]

Hello, thank you for your interest in this project!
Tuple bindings are covered a bit differently due to historical reasons. Which is why the return type is missing.

I believe the problem is centered around:

fantomas/src/Fantomas.Core/CodePrinter.fs

Lines 2866 to 2867 in 0ce91b7

	let genDestructedTuples =
	expressionFitsOnRestOfLine (genPat pat) (sepOpenT +> genPat pat +> sepCloseT)

There we could do something like:

let genDestructedTuples =
    expressionFitsOnRestOfLine (genPat pat) (sepOpenT +> genPat pat +> sepCloseT)
    +> optSingle
        (fun (rt: BindingReturnInfoNode) ->
            genSingleTextNode rt.Colon
            +> sepSpace
            +> atCurrentColumnIndent (genType rt.Type))
        b.ReturnType

to print the return type when it is present.

I'm not sure how well this exact fix would play when the tuple is multiline.
Something like

let a, //
    b, //
    c 
         : int * int * int = 1,2,3

Might be a corner case.

Are you interested in submitting a PR for this one?