Remove unused set_tag from compiler internals.

jscomp/core/j.ml

@@ -161,7 +161,6 @@ and expression_desc =
      you have to use [E.tag] in a safe way
   *)
   | Caml_block_tag of expression
-  (* | Caml_block_set_tag of expression * expression *)
   (* | Caml_block_set_length of expression * expression *)
   (* It will just fetch tag, to make it safe, when creating it,
      we need apply "|0", we don't do it in the

jscomp/core/js_analyzer.ml

@@ -104,7 +104,6 @@ let rec no_side_effect_expression_desc (x : J.expression_desc) =
   | Length (e, _) | Caml_block_tag e | Typeof e -> no_side_effect e
   | Bin (op, a, b) -> op <> Eq && no_side_effect a && no_side_effect b
   | Js_not _ | Cond _ | FlatCall _ | Call _ | New _ | Raw_js_code _
-  (* | Caml_block_set_tag _  *)
   (* actually true? *) ->
       false
   | Await _ -> false

jscomp/others/belt_internals.mli

@@ -58,8 +58,6 @@ module Obj : sig
   external field : t -> int -> t = "%obj_field" 
   external set_field : t -> int -> t -> unit = "%obj_set_field"
   external tag : t -> int = "?obj_tag" 
-  (* The compiler ensures (|0) operation *)
-  external set_tag : t -> int -> unit = "TAG" [@@bs.set]  
   external repr : 'a -> t = "%identity"
   external obj : t -> 'a = "%identity"
   external magic : 'a -> 'b = "%identity"  

jscomp/runtime/bs_stdlib_mini.mli

@@ -58,8 +58,6 @@ module Obj : sig
   external field : t -> int -> t = "%obj_field" 
   external set_field : t -> int -> t -> unit = "%obj_set_field"
   external tag : t -> int = "?obj_tag" 
-  (* The compiler ensures (|0) operation *)
-  external set_tag : t -> int -> unit = "TAG" [@@bs.set]  
   external repr : 'a -> t = "%identity"
   external obj : t -> 'a = "%identity"
   external magic : 'a -> 'b = "%identity"  

jscomp/stdlib-406/camlinternalLazy.ml

@@ -46,7 +46,6 @@ exception Undefined
 
 let%private forward_with_closure (type a ) (blk : a t) (closure : unit -> a [@bs]) : a = 
   let result = closure () [@bs] in
-  (* do set_field BEFORE set_tag *)
   blk.value <- result;
   blk.tag<- true;
   result

jscomp/stdlib-406/obj.mli

@@ -42,12 +42,7 @@ external field : t -> int -> t = "%obj_field"
 
     [set_field] MUST NOT be called on immutable blocks.  (Blocks allocated
     in C stubs, or with [new_block] below, are always considered mutable.)
-
-    The same goes for [set_double_field] and [set_tag].  However, for
-    [set_tag], in the case of immutable blocks where the middle-end optimizers
-    never see code that discriminates on their tag (for example records), the
-    operation should be safe.  Such uses are nonetheless discouraged.
-
+    
     For experts only:
     [set_field] et al can be made safe by first wrapping the block in
     {!Sys.opaque_identity}, so any information about its contents will not