Hello, thanks for taking the time to spend some time on this.

At first glance, this PR is more about how we currently merge AttributeLists together in the genOnelinerAttributes where there is trivia involved that doesn't lead to accurate results.

Something like

type A = B
and [<X>][<Y>][<Z>] C = D

gets transformed to

type A = B
and [<X; Y; Z>] C = D

It is questionable if we should do this in the first place. The style guide doesn't explicitly state this and I believe Fantomas should not really transform this code.

If we processed each attribute list individually, the trivia would be restored accordingly.
And we could use a different formatting style when all lists don't fit on one line.

Something like:

type A = B
and
    [<X>] // comment makes it multiline
    [<Y>]
    [<Z>] 
    C = D

On a practical note, I'm reluctant to merge these changes as everything will change anyway in #2626.
That branch is about 87% complete so I prefer to tackle it over there instead.
As your PR would need to tackle v5.2 anyway and would be superseded by #2626 before the stable release anyway.

Hey, thanks for response.

Hello, thanks for taking the time to spend some time on this.

At first glance, this PR is more about how we currently merge AttributeLists together in the genOnelinerAttributes where there is trivia involved that doesn't lead to accurate results.

Something like

type A = B
and [<X>][<Y>][<Z>] C = D

gets transformed to

type A = B
and [<X; Y; Z>] C = D

Agreed, genOnelinerAttributes works this way.

It is questionable if we should do this in the first place. The style guide doesn't explicitly state this and I believe Fantomas should not really transform this code.

If we processed each attribute list individually, the trivia would be restored accordingly. And we could use a different formatting style when all lists don't fit on one line.

Something like:

type A = B
and
    [<X>] // comment makes it multiline
    [<Y>]
    [<Z>] 
    C = D

genAttributes should work this way.

Maybe we want to remove genOnelinerAttributes in favor of genAttributes?

On a practical note, I'm reluctant to merge these changes as everything will change anyway in #2626. That branch is about 87% complete so I prefer to tackle it over there instead. As your PR would need to tackle v5.2 anyway and would be superseded by #2626 before the stable release anyway.

Sounds good, #2626 moved forward during time I was working on this, and I want to look at it anyways. Wasn't aware that Project Dallas is so close to stable version :)

I am closing this PR, and revisit it for v5.2 when things will be ready for it.