Fix position of expressions regarding of comments in infix-op expressions

src/Ast.ml

@@ -861,6 +861,8 @@ and Requires_sub_terms : sig
   val parenze_pat : pattern In_ctx.xt -> bool
 
   val parenze_exp : expression In_ctx.xt -> bool
+
+  val parenze_nested_exp : expression In_ctx.xt -> bool
 end = struct
   open In_ctx
 
@@ -2393,7 +2395,40 @@ end = struct
     | Ptyp_tuple l -> exposed_right_typ (List.last_exn l)
     | Ptyp_object _ -> true
     | _ -> false
+
+  let parenze_nested_exp {ctx; ast= exp} =
+    let infix_prec ast =
+      match ast with
+      | Exp {pexp_desc= Pexp_apply (e, _); _} when is_infix e ->
+          prec_ast ast
+      | Exp
+          ( { pexp_desc=
+                Pexp_construct
+                  ( {txt= Lident "::"; loc= _}
+                  , Some
+                      { pexp_desc= Pexp_tuple [_; _]
+                      ; pexp_loc= _
+                      ; pexp_attributes= _
+                      ; _ } )
+            ; pexp_loc= _
+            ; pexp_attributes= _
+            ; _ } as exp )
+        when not (is_sugared_list exp) ->
+          prec_ast ast
+      | _ -> None
+    in
+    (* Make the precedence explicit for infix operators *)
+    match (infix_prec ctx, infix_prec (Exp exp)) with
+    | Some (InfixOp0 | ColonEqual), _ | _, Some (InfixOp0 | ColonEqual) ->
+        (* special case for refs update and all InfixOp0 to reduce parens
+           noise *)
+        false
+    | None, _ | _, None -> false
+    | Some p1, Some p2 -> Poly.(p1 <> p2)
 end
 
 include In_ctx
 include Requires_sub_terms
+
+let is_monadic_expr e =
+  match prec_ast (Exp e) with Some InfixOp0 -> true | _ -> false

src/Ast.mli

@@ -41,6 +41,8 @@ val index_op_set_sugar :
   -> ((string * Char.t * Char.t) Location.loc * expression list * expression)
      option
 
+val is_monadic_expr : expression -> bool
+
 val is_monadic_binding_id : string -> bool
 
 val is_monadic_binding : expression -> bool
@@ -206,6 +208,10 @@ val parenze_exp : expression xt -> bool
 (** [parenze_exp xexp] holds when expression-in-context [xexp] should be
     parenthesized. *)
 
+val parenze_nested_exp : expression xt -> bool
+(** [parenze_nested_exp xexp] holds when nested expression-in-context [xexp]
+    should be parenthesized. *)
+
 val parenze_mty : module_type xt -> bool
 (** [parenze_mty xmty] holds when module_type-in-context [xmty] should be
     parenthesized. *)

src/Cmts.ml

@@ -378,8 +378,8 @@ let relocate (t : t) ~src ~before ~after =
         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)
+      |>
+      List.sort ~compare:(Comparable.lift Location.compare_start ~f:Cmt.loc)
     in
     update_multi t.cmts_before src before ~f:merge_and_sort ;
     update_multi t.cmts_after src after ~f:merge_and_sort ;
@@ -626,15 +626,16 @@ let has_after t loc =
 let remaining_comments t =
   let get t before_after =
     Hashtbl.to_alist t
-    |> List.concat_map ~f:(fun (ast_loc, cmts) ->
-           List.map cmts ~f:(fun (cmt : Cmt.t) ->
-               ( cmt
-               , before_after
-               , let open Sexp in
-                 List
-                   [ List [Atom "ast_loc"; Location.sexp_of_t ast_loc]
-                   ; List [Atom "cmt_loc"; Location.sexp_of_t cmt.loc]
-                   ; List [Atom "cmt_txt"; Atom cmt.txt] ] )))
+    |>
+    List.concat_map ~f:(fun (ast_loc, cmts) ->
+        List.map cmts ~f:(fun (cmt : Cmt.t) ->
+            ( cmt
+            , before_after
+            , let open Sexp in
+              List
+                [ List [Atom "ast_loc"; Location.sexp_of_t ast_loc]
+                ; List [Atom "cmt_loc"; Location.sexp_of_t cmt.loc]
+                ; List [Atom "cmt_txt"; Atom cmt.txt] ] )))
   in
   List.concat
     [ get t.cmts_before "before"