More review and diff-reduction

src/ocaml/typing/ctype.ml

@@ -1511,6 +1511,7 @@ let copy_sep ~copy_scope ~fixed ~(visited : type_expr TypeHash.t) sch =
     let univars = free ty in
     if is_Tvar ty || may_share && TypeSet.is_empty univars then
       if get_level ty <> generic_level then ty else
+      (* jkind not consulted during copy_sep, so Any is safe *)
       let t = newstub ~scope:(get_scope ty) (Jkind.any ~why:Dummy_jkind) in
       add_delayed_copy t ty;
       t
@@ -2165,7 +2166,14 @@ let is_immediate64 env ty =
     Btype.backtrack snap;
     result
   else
-    perform_check ()
+    (* CR layouts v2.8: Remove the backtracking once mode crossing is
+       implemented correctly; it's needed for now because checking whether
+       a jkind is immediate (rightly) sets the sort to be Value. It worked
+       previous to this patch because the subjkind check failed earlier. *)
+    let snap = Btype.snapshot () in
+    let result = perform_check () in
+    Btype.backtrack snap;
+    result
 
 (* We will require Int63 to be [global many unique] on 32-bit platforms, so
    this is fine *)

src/ocaml/typing/ctype.mli

@@ -471,12 +471,12 @@ val remove_mode_and_jkind_variables: type_expr -> unit
         (* Ensure mode and jkind variables are fully determined *)
 
 val nongen_vars_in_schema: Env.t -> type_expr -> Btype.TypeSet.t option
-        (* Return any non-generic variables in the type scheme,
-           and ensure mode variables are fully determined *)
+        (* Return any non-generic variables in the type scheme. Also ensures
+           mode variables are fully determined. *)
 
 val nongen_vars_in_class_declaration:class_declaration -> Btype.TypeSet.t option
-        (* Return any non-generic variables in the class type, and ensures mode
-           variables are fully determined.  Uses the empty environment.  *)
+        (* Return any non-generic variables in the class type. Also ensures
+           mode variables are fully determined. Uses the empty environment.  *)
 
 type variable_kind = Row_variable | Type_variable
 type closed_class_failure = {

src/ocaml/typing/datarepr.ml

@@ -108,7 +108,7 @@ let constructor_descrs ~current_unit ty_path decl cstrs rep =
          let all_void = all_void jkinds in
          if all_void then incr num_consts else incr num_nonconsts;
          all_void)
-      cstr_arg_jkinds
+      cstr_arg_jkindsNick Roberts
   in
   let describe_constructor (src_index, const_tag, nonconst_tag, acc)
         {cd_id; cd_args; cd_res; cd_loc; cd_attributes; cd_uid} =
@@ -130,7 +130,7 @@ let constructor_descrs ~current_unit ty_path decl cstrs rep =
       (* This is the representation of the inner record, IF there is one *)
       let record_repr = Record_inlined (cstr_tag, rep) in
       constructor_args ~current_unit decl.type_private cd_args cd_res
-        (Path.Pextra_ty (ty_path, Pcstr_ty cstr_name)) record_repr
+        Path.(Pextra_ty (ty_path, Pcstr_ty cstr_name)) record_repr
     in
     let cstr =
       { cstr_name;

src/ocaml/typing/env.ml

@@ -2870,8 +2870,8 @@ let add_language_extension_types env =
    turned on.  We can't do this at startup because command line flags haven't
    been parsed yet. So, we make the initial environment lazy.
 
-   If language extensions are adjusted after [initial_safe_string] and
-   [initial_unsafe_string] are forced, these environments may be inaccurate.
+   If language extensions are adjusted after [initial] is forced, these
+   environments may be inaccurate.
 *)
 let initial = add_language_extension_types initial
 

src/ocaml/typing/env.mli

@@ -59,11 +59,10 @@ type address =
 type t
 
 val empty: t
-(* This environment is lazy so that it may depend on the enabled
-   extensions, typically adjusted via command line flags.  If extensions are
-   changed after this environment is forced, it may be inaccurate.  This
-   could happen, for example, if extensions are adjusted via the
-   compiler-libs. *)
+(* This environment is lazy so that it may depend on the enabled extensions,
+   typically adjusted via command line flags.  If extensions are changed after
+   theis environment is forced, they may be inaccurate.  This could happen, for
+   example, if extensions are adjusted via the compiler-libs. *)
 val initial: t Lazy.t
 val diff: t -> t -> Ident.t list