Fantomas strips quotes from quoted type-parameters

[JohSand]

Issue created from fantomas-online

Code

let repro (t: '``QuotedWithIllegalChar<'T>``) = ()

Result

let repro (t: 'QuotedWithIllegalChar<'T>) = ()

Problem description

Sometimes it is useful to have type-parameters in quotes, allowing them to contain characters such as '<' and '>'. After formatting, this quotation is lost, leading to non-compiling code.

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 main branch at 2023-05-05T09:52:15Z - 4093fa5

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, thank you for your interest in this project.

It appears we are not processing the ident text of a SynTypar in

fantomas/src/Fantomas.Core/ASTTransformer.fs

Lines 1976 to 1985 in 9298c26

	let mkSynTypar (SynTypar(ident, req, _)) =
	let range =
	mkRange
	ident.idRange.FileName
	(Position.mkPos ident.idRange.StartLine (ident.idRange.StartColumn - 1))
	ident.idRange.End
	match req with
	| TyparStaticReq.None -> stn $"'{ident}" range
	| TyparStaticReq.HeadType -> stn $"^{ident.idText}" range

Some check along these lines could do the trick:

let mkSynTypar (SynTypar(ident, req, _)) =
    let range =
        mkRange
            ident.idRange.FileName
            (Position.mkPos ident.idRange.StartLine (ident.idRange.StartColumn - 1))
            ident.idRange.End

    let identText =
        let width = ident.idRange.EndColumn - ident.idRange.StartColumn
        // 5 because of ^ or ' and `` on each side
        if ident.idText.Length + 5 = width then
            $"``{ident.idText}``"
        else
            ident.idText

    match req with
    | TyparStaticReq.None -> stn $"'{identText}" range
    | TyparStaticReq.HeadType -> stn $"^{identText}" range

Are you interested in submitting a PR for this?

[JohSand]

I'm willing to give it a try.