Feature request: improve the behavior of --no-comment-check

[hhugo]

Ideally, --no-comment-check should not complain if an unattached doc comment (warning 50) becomes attached.
The current behavior is that we see an "Ast changed" error because there is an extra "doc" atttribute corresponding to that comment.

[Julow]

The current error is correct in that the AST changes. Though, that might be acceptable behind a flag.

Do you have an example of an unattached doc comment that becomes attached ?

[hhugo]

The purpose of the request is to help classify bugs found in opam, I've added a bunch of problematic files in #985

[Julow]

Thanks! I did not expect this bug to be possible but here's one example from your list:

open Vg
;;

(** Images for the documentation. *)

becomes:

open Vg

(** Images for the documentation. *);;

[hhugo]

Looking more into this, it seems that
Normalize_std_ast.equal ~ignore_doc_comments:true doesn't ignore floating doc comment inside Pctf_attribute, Psig_attribute, Pstr_attribute and Pcf_attribute