Idempotency problem when a comment appears in a function application

[joprice]

Issue created from fantomas-online

Formatted code

x
    (
    // abc
    // abc
    fun x -> x)

Reformatted code

x
    (
    // abc
    // abc
    // abc
    // abc
    fun x -> x)

Problem description

Fantomas was not able to produce the same code after reformatting the result.

This occurs when there is a comment in a function applicatin before an anonymous function's fun keyword. The text of the comment is doubled on each format.

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]

Hi there,

Thank you for reporting this issue! It appears that the trivia for ExprLambdaNode is being printed twice (see online tool).

Off the top of my head, I would guess this occurs in CodePrinter.fs, where genNode may be called for the same node twice, possibly due to the lambda being a child of ExprAppWithLambdaNode.

Would you be interested in submitting a PR for this?