Improve a bit the break rules

lib/Ast.ml

@@ -1521,9 +1521,7 @@ end = struct
     (* String literals using the heavy syntax are not simple. *)
     | Pexp_constant {pconst_desc= Pconst_string (_, _, Some _); _} -> false
     (* Only strings fitting on the line are simple. *)
-    | Pexp_constant {pconst_desc= Pconst_string (_, loc, None); _} ->
-        Exp.is_trivial exp
-        || (Location.height loc = 1 && fit_margin c (width xexp))
+    | Pexp_constant {pconst_desc= Pconst_string (_, _, None); _} -> true
     | Pexp_constant _ -> true
     | Pexp_field _ | Pexp_ident _ | Pexp_send _
      |Pexp_construct (_, None)

lib/Cmts.ml

@@ -303,8 +303,8 @@ let rec place t loc_tree ?prev_loc ?deep_loc locs cmts =
 (** Relocate comments, for Ast transformations such as sugaring. *)
 let relocate (t : t) ~src ~before ~after =
   if t.debug then
-    Format.eprintf "relocate %a to %a and %a@\n%!" Location.fmt src
-      Location.fmt before Location.fmt after ;
+    Format.eprintf "relocate %a to %a and %a@\n%!"
+      Location.fmt src Location.fmt before Location.fmt after ;
   let merge_and_sort x y =
     List.rev_append x y
     |> List.sort ~compare:(Comparable.lift Location.compare_start ~f:Cmt.loc)

lib/Conf_decl.ml

@@ -187,8 +187,8 @@ let rec pp_from fs = function
   | `Profile (s, p) -> Format.fprintf fs " (profile %s%a)" s pp_from_src p
   | `Updated (x, None) -> pp_from_src fs x
   | `Updated (x, Some r) ->
-      Format.fprintf fs "%a -- Warning (redundant): %a" pp_from_src x pp_from
-        r
+      Format.fprintf fs "%a -- Warning (redundant): %a"
+        pp_from_src x pp_from r
 
 let loc_udapted_from = function
   | `Commandline -> Location.in_file "<command-line>"

lib/Fmt_ast.ml

@@ -1520,13 +1520,14 @@ and fmt_args_grouped ?epi:(global_epi = noop) c ctx args =
     let xexp = sub_exp ~ctx x in
     is_simple c.conf (expression_width c) xexp
   in
-  let should_break_after x = not (is_simple x)
-  and should_break_before ((_lbl, exp) as y) =
+  let should_break_before x = not (is_simple x)
+  and should_break_after ((_lbl, exp) as y) =
     match exp.pexp_desc with
     (* Heavy syntax strings are not grouped. *)
     | Pexp_constant {pconst_desc= Pconst_string (_, _, Some _); _} -> true
     (* Non-simple strings are grouped but end a group. *)
-    | Pexp_constant {pconst_desc= Pconst_string (_, _, None); _} -> false
+    | Pexp_constant {pconst_desc= Pconst_string (str, _, None); _} ->
+        String.length str * 3 > c.conf.fmt_opts.margin.v
     | _ -> not (is_simple y)
   in
   let break x y =

test/passing/tests/infix_arg_grouping.ml.ref

@@ -5,8 +5,8 @@ vbox 1
 ;;
 
 user_error
-  ( "version mismatch: .ocamlformat requested "
-  ^ value ^ " but version is " ^ Version.version )
+  ( "version mismatch: .ocamlformat requested " ^ value ^ " but version is "
+  ^ Version.version )
 ;;
 
 hvbox 1