Fix indexing operators precedence

CHANGES.md

@@ -1,5 +1,6 @@
 ### (master)
 
+  + Fix indexing operators precedence (#1039) (Jules Aguillon)
   + Fix dropped comment after infix op (#1030) (Guillaume Petiot)
   + Fix: no newline if the input is empty (#1031) (Guillaume Petiot)
   + Fix unstable comments around attributes (#1029) (Guillaume Petiot)

src/Ast.ml

@@ -144,7 +144,10 @@ let index_op_get_sugar ({txt= ident; loc} : Longident.t Location.loc) args =
       , [{pexp_desc= Pexp_array l; _}] )
       when List.length l > 3 ->
         Some ({Location.txt= index_op_bigarray; loc}, l)
-    | _ -> None )
+    | lid, args -> (
+      match index_op_get_lid lid with
+      | None -> None
+      | Some index_op -> Some ({Location.txt= index_op; loc}, args) ) )
 
 let index_op_set_sugar ({txt= ident; loc} : Longident.t Location.loc) args =
   match all_args_unlabeled args with
@@ -165,6 +168,10 @@ let index_op_set_sugar ({txt= ident; loc} : Longident.t Location.loc) args =
       , [{pexp_desc= Pexp_array l; _}; e] )
       when List.length l > 3 ->
         Some ({Location.txt= index_op_bigarray; loc}, l, e)
+    | lid, [argi; arge] -> (
+      match index_op_set_lid lid with
+      | None -> None
+      | Some index_op -> Some ({Location.txt= index_op; loc}, [argi], arge) )
     | _ -> None )
 
 let is_index_op exp =
@@ -1636,13 +1643,13 @@ end = struct
           | _ -> Some (Apply, Non) ) )
       | Pexp_apply ({pexp_desc= Pexp_ident ident; _}, (Nolabel, a1) :: args)
         when Option.is_some (index_op_get_sugar ident args) ->
-          if a1 == exp then Some (Dot, Left) else Some (Comma, Left)
+          if a1 == exp then Some (Dot, Left) else Some (LessMinus, Left)
       | Pexp_apply ({pexp_desc= Pexp_ident ident; _}, (Nolabel, a1) :: args)
         when Option.is_some (index_op_set_sugar ident args) ->
           let _, _, e = Option.value_exn (index_op_set_sugar ident args) in
           if a1 == exp then Some (Dot, Left)
-          else if e == exp then Some (Comma, Right)
-          else Some (Comma, Left)
+          else if e == exp then Some (LessMinus, Right)
+          else Some (LessMinus, Left)
       | Pexp_apply
           ({pexp_desc= Pexp_ident {txt= Lident i; _}; _}, [(_, e1); _]) -> (
           let child = if e1 == exp then Left else Right in
@@ -1725,7 +1732,7 @@ end = struct
           Some Dot
       | Pexp_apply ({pexp_desc= Pexp_ident ident; _}, (Nolabel, _) :: args)
         when Option.is_some (index_op_set_sugar ident args) ->
-          Some Comma
+          Some LessMinus
       | Pexp_apply ({pexp_desc= Pexp_ident {txt= Lident i; _}; _}, [_; _])
         -> (
         match (i.[0], i) with

src/Fmt_ast.ml

@@ -1670,26 +1670,6 @@ and fmt_expression c ?(box = true) ?pro ?epi ?eol ?parens ?(indent_wrap = 0)
                      , (fmt_op, args) )
                  | None -> (false, noop, noop, (noop, args))))
         $ fmt_atrs )
-  | Pexp_apply
-      ( { pexp_desc= Pexp_ident {txt= id; loc}
-        ; pexp_loc
-        ; pexp_attributes= _
-        ; _ }
-      , (Nolabel, s) :: (Nolabel, i) :: _ )
-    when Option.is_some (index_op_get_lid id) ->
-      let index_op = Option.value_exn (index_op_get_lid id) in
-      Cmts.relocate c.cmts ~src:pexp_loc ~before:loc ~after:loc ;
-      fmt_index_op c ctx ~parens {txt= index_op; loc} s [i]
-  | Pexp_apply
-      ( { pexp_desc= Pexp_ident {txt= id; loc}
-        ; pexp_loc
-        ; pexp_attributes= _
-        ; _ }
-      , (Nolabel, s) :: (Nolabel, i) :: (Nolabel, e) :: _ )
-    when Option.is_some (index_op_set_lid id) ->
-      let index_op = Option.value_exn (index_op_set_lid id) in
-      Cmts.relocate c.cmts ~src:pexp_loc ~before:loc ~after:loc ;
-      fmt_index_op c ctx ~parens {txt= index_op; loc} s [i] ~set:e
   | Pexp_apply (e0, [(Nolabel, e1)]) when is_prefix e0 ->
       hvbox 2
         (wrap_exp c ~loc:pexp_loc ~parens

test/passing/index_op.ml

@@ -17,7 +17,7 @@ let h = Hashtbl.create 17
 ;;
 h.@("One") <- 1 ;
 assert (h.@{"One"} = 1) ;
-print_int (h.@{"One"}) ;
+print_int h.@{"One"} ;
 assert (h.?["Two"] = None)
 
 (* from GPR#1392 *)
@@ -81,3 +81,35 @@ let () =
   m.Mat.${[[2]; [5]]} |> ignore ;
   let open Mat in
   m.${[[2]; [5]]} |> ignore
+
+let _ = (x.*{(y, z)} <- w) @ []
+
+let _ = (x.{y, z} <- w) @ []
+
+let _ = (x.*(y) <- z) @ []
+
+let _ = (x.*(y) <- z) := []
+
+let _ = ((x.*(y) <- z), [])
+
+let _ = x.*(y) <- z ; []
+
+let _ = (x.(y) <- z) @ []
+
+let _ = (x.(y) <- z) := []
+
+let _ = ((x.(y) <- z), [])
+
+let _ = x.(y) <- z ; []
+
+let _ = (x.y <- z) @ []
+
+let _ = (x.y <- z) := []
+
+let _ = ((x.y <- z), [])
+
+let _ =
+  x.y <- z ;
+  []
+
+let _ = x.(y) <- (z.(w) <- u)