Bug: Unable to process two files using 0.28.1

[psafont]

Describe the bug
Ocamlformat output instructed me to open an issue for these files:

ocamlformat: Cannot process "ocaml/xapi/xapi_mgmt_iface.ml".
  Please report this bug at https://github.com/ocaml-ppx/ocamlformat/issues.
  BUG: formatting did not stabilize after 10 iterations.

ocamlformat: Cannot process "ocaml/xapi/extauth_plugin_ADwinbind.ml".
  Please report this bug at https://github.com/ocaml-ppx/ocamlformat/issues.
  BUG: formatting did not stabilize after 10 iterations.

How to Reproduce
Steps to reproduce the behaviour:

• The formatted files are:
  • https://github.com/psafont/xen-api/blob/dev/pau/oformat.28.1/ocaml/xapi/xapi_mgmt_iface.ml
  • https://github.com/psafont/xen-api/blob/dev/pau/oformat.28.1/ocaml/xapi/extauth_plugin_ADwinbind.ml
• What are the selected options? See https://github.com/psafont/xen-api/blob/dev/pau/oformat.28.1/.ocamlformat

Output of ocamlformat --print-config:

comment-check=true
debug=false
disable=false
margin-check=false
max-iters=10
ocaml-version=4.14 (file .ocamlformat:10)
quiet=false
disable-conf-attrs=false
version-check=true
assignment-operator=end-line (profile ocamlformat (file .ocamlformat:1))
break-before-in=fit-or-vertical (profile ocamlformat (file .ocamlformat:1))
break-cases=nested (profile ocamlformat (file .ocamlformat:1))
break-collection-expressions=fit-or-vertical (profile ocamlformat (file .ocamlformat:1))
break-colon=after (profile ocamlformat (file .ocamlformat:1))
break-fun-decl=wrap (profile ocamlformat (file .ocamlformat:1))
break-fun-sig=wrap (profile ocamlformat (file .ocamlformat:1))
break-infix=fit-or-vertical (file .ocamlformat:7)
break-infix-before-func=false (file .ocamlformat:8)
break-separators=before (file .ocamlformat:6) -- Warning (redundant):  (profile ocamlformat (file .ocamlformat:1))
break-sequences=false (profile ocamlformat (file .ocamlformat:1))
break-string-literals=auto (profile ocamlformat (file .ocamlformat:1))
break-struct=natural (file .ocamlformat:5)
cases-exp-indent=4 (profile ocamlformat (file .ocamlformat:1))
cases-matching-exp-indent=compact (profile ocamlformat (file .ocamlformat:1))
disambiguate-non-breaking-match=false (profile ocamlformat (file .ocamlformat:1))
doc-comments=before-except-val (profile ocamlformat (file .ocamlformat:1))
doc-comments-padding=2 (profile ocamlformat (file .ocamlformat:1))
doc-comments-tag-only=default (profile ocamlformat (file .ocamlformat:1))
dock-collection-brackets=true (file .ocamlformat:4)
exp-grouping=preserve (profile ocamlformat (file .ocamlformat:1))
extension-indent=2 (profile ocamlformat (file .ocamlformat:1))
field-space=tight (profile ocamlformat (file .ocamlformat:1))
function-indent=2 (profile ocamlformat (file .ocamlformat:1))
function-indent-nested=never (profile ocamlformat (file .ocamlformat:1))
if-then-else=fit-or-vertical (file .ocamlformat:3)
indent-after-in=0 (profile ocamlformat (file .ocamlformat:1))
indicate-multiline-delimiters=closing-on-separate-line (file .ocamlformat:2)
indicate-nested-or-patterns=space (profile ocamlformat (file .ocamlformat:1))
infix-precedence=indent (profile ocamlformat (file .ocamlformat:1))
leading-nested-match-parens=false (profile ocamlformat (file .ocamlformat:1))
let-and=compact (profile ocamlformat (file .ocamlformat:1))
let-binding-indent=2 (profile ocamlformat (file .ocamlformat:1))
let-binding-deindent-fun=true (profile ocamlformat (file .ocamlformat:1))
let-binding-spacing=compact (profile ocamlformat (file .ocamlformat:1))
let-module=compact (profile ocamlformat (file .ocamlformat:1))
line-endings=lf (profile ocamlformat (file .ocamlformat:1))
margin=80 (profile ocamlformat (file .ocamlformat:1))
match-indent=0 (profile ocamlformat (file .ocamlformat:1))
match-indent-nested=never (profile ocamlformat (file .ocamlformat:1))
max-indent=68 (profile ocamlformat (file .ocamlformat:1))
module-indent=2 (profile ocamlformat (file .ocamlformat:1))
module-item-spacing=sparse (profile ocamlformat (file .ocamlformat:1))
nested-match=wrap (profile ocamlformat (file .ocamlformat:1))
ocp-indent-compat=false (profile ocamlformat (file .ocamlformat:1))
parens-ite=false (profile ocamlformat (file .ocamlformat:1))
parens-tuple=always (profile ocamlformat (file .ocamlformat:1))
parens-tuple-patterns=multi-line-only (profile ocamlformat (file .ocamlformat:1))
parse-docstrings=false (profile ocamlformat (file .ocamlformat:1))
parse-toplevel-phrases=false (profile ocamlformat (file .ocamlformat:1))
sequence-blank-line=preserve-one (file .ocamlformat:9)
sequence-style=separator (profile ocamlformat (file .ocamlformat:1))
single-case=compact (profile ocamlformat (file .ocamlformat:1))
space-around-arrays=false (profile ocamlformat (file .ocamlformat:1))
space-around-lists=false (profile ocamlformat (file .ocamlformat:1))
space-around-records=false (profile ocamlformat (file .ocamlformat:1))
space-around-variants=false (profile ocamlformat (file .ocamlformat:1))
stritem-extension-indent=0 (profile ocamlformat (file .ocamlformat:1))
type-decl=compact (profile ocamlformat (file .ocamlformat:1))
type-decl-indent=2 (profile ocamlformat (file .ocamlformat:1))
wrap-comments=false (profile ocamlformat (file .ocamlformat:1))
wrap-fun-args=true (profile ocamlformat (file .ocamlformat:1))
profile=ocamlformat (file .ocamlformat:1)

I tried to debug the output using --debug, but it was too big for me to make sense of it

[EmileTrotignon]

Thanks for the report !

--debug on such a large file is unlikely to be helpful.

Correct way to go about understanding what is happening is to extract a minimal example. I would start by deleting ~ half the code to see if the error is still there, and keep doing that on the part with the error until there is only the guilty function left. Then the function in question can be simplified.

Doing this work is helpful, and the results can be posted here.

[psafont]

That was very useful, here are a much more minimal reproduction cases:

module Server : sig
end = struct
  let start ~__context ?addr () =
    if Pool_role.is_master () && addr = None then
      (* NB if we synchronously bring up the management interface on a master with a blank
         database this can fail... this is ok because the database will be synchronised later *)
      Server_helpers.exec_with_new_task "refreshing consoles" (fun __context ->
          Dbsync_master.set_master_ip ~__context ;
          Helpers.update_getty () ;
          Dbsync_master.refresh_console_urls ~__context
      )
end

@@ -3,8 +3,7 @@ module Server : sig end = struct
     if Pool_role.is_master () && addr = None then
       (* NB if we synchronously bring up the management interface on a master with a blank
          database this can fail... this is ok because the database will be synchronised later *)
-        Server_helpers.exec_with_new_task "refreshing consoles"
-          (fun __context ->
+      Server_helpers.exec_with_new_task "refreshing consoles" (fun __context ->
           Dbsync_master.set_master_ip ~__context ;
           Helpers.update_getty () ;
           Dbsync_master.refresh_console_urls ~__context
ocamlformat: Cannot process "ocaml/xapi/xapi_mgmt_iface.ml".
  Please report this bug at https://github.com/ocaml-ppx/ocamlformat/issues.
  BUG: formatting did not stabilize after 10 iterations.

and

let domain_name_of_netbios netbios =
  let cache_domain netbios domain_name current_map =
    let new_map = StringMap.add netbios domain_name current_map in
    if Atomic.compare_and_set domain_netbios_name_map current_map new_map = true
    then (* Just ignore it if update fail, as it will be cached next time *)
      debug "Cached netbios '%s' -> domain '%s'" netbios domain_name
  in
  ()

@@ -2,8 +2,7 @@ let domain_name_of_netbios netbios =
   let cache_domain netbios domain_name current_map =
     let new_map = StringMap.add netbios domain_name current_map in
     if Atomic.compare_and_set domain_netbios_name_map current_map new_map = true
-    then
-      (* Just ignore it if update fail, as it will be cached next time *)
+    then (* Just ignore it if update fail, as it will be cached next time *)
       debug "Cached netbios '%s' -> domain '%s'" netbios domain_name
   in
   ()
ocamlformat: Cannot process "ocaml/xapi/extauth_plugin_ADwinbind.ml".
  Please report this bug at https://github.com/ocaml-ppx/ocamlformat/issues.
  BUG: formatting did not stabilize after 10 iterations.

It's the comments right after the then that are causing the issue, moving the comment away from that position is useful to work around the issue.