fix uniqueness_analysis for unboxed tuple

ocaml/testsuite/tests/typing-unique/unique_analysis.ml

@@ -1,5 +1,5 @@
-  (* TEST
- flags += "-extension unique";
+(* TEST
+ flags += "-extension unique -extension layouts_beta";
  expect;
 *)
 
@@ -782,3 +782,29 @@ Line 3, characters 20-21:
                         ^
 
 |}]
+
+let foo () =
+  let t = #("hello", "world") in
+  let unique_use_tuple : ('a : value & value). unique_ 'a -> unit = fun _ -> () in
+  unique_use_tuple t;
+  let #(_, _) = t in
+  ()
+[%%expect{|
+val foo : unit -> unit = <fun>
+|}]
+
+let foo () =
+  let t = ("hello", "world") in
+  ignore (unique_id t);
+  let (_, _) = t in
+  ()
+[%%expect{|
+Line 4, characters 6-12:
+4 |   let (_, _) = t in
+          ^^^^^^
+Error: This value is read from here, but it has already been used as unique:
+Line 3, characters 20-21:
+3 |   ignore (unique_id t);
+                        ^
+
+|}]

ocaml/typing/uniqueness_analysis.ml

@@ -1101,8 +1101,6 @@ and pattern_match_single pat paths : Ienv.Extension.t * UF.t =
     in
     ext, UF.par uf_read uf_args
   | Tpat_unboxed_tuple args ->
-    (* XXX modes *)
-    let uf_read = Paths.mark_implicit_borrow_memory_address Read occ paths in
     let ext, uf_args =
       List.mapi
         (fun i (_, arg, _) ->
@@ -1111,7 +1109,7 @@ and pattern_match_single pat paths : Ienv.Extension.t * UF.t =
         args
       |> conjuncts_pattern_match
     in
-    ext, UF.par uf_read uf_args
+    ext, uf_args
 
 let pattern_match pat = function
   | Match_tuple values -> pattern_match_tuple pat values