flambda-backend: Use "unboxable" as the name of the best-effort unboxing attribute (#2319)

Author: mshinwell

lambda/printlambda.ml

@@ -944,7 +944,7 @@ let rec lam ppf = function
                 let { unbox_param } = p.attributes in
                 fprintf ppf "@ %a%s%a%s"
                   Ident.print p.name (alloc_kind p.mode) layout p.layout
-                  (if unbox_param then "[@unboxed]" else "")
+                  (if unbox_param then "[@unboxable]" else "")
               ) params
         | Tupled ->
             fprintf ppf " (";
@@ -956,7 +956,7 @@ let rec lam ppf = function
                  Ident.print ppf p.name;
                  Format.fprintf ppf "%s" (alloc_kind p.mode);
                  layout ppf p.layout;
-                 if unbox_param then Format.fprintf ppf "[@unboxed]"
+                 if unbox_param then Format.fprintf ppf "[@unboxable]"
               )
               params;
             fprintf ppf ")" in

lambda/translattribute.ml

@@ -53,8 +53,8 @@ let is_loop_attribute =
 let is_opaque_attribute =
   [ ["opaque"; "ocaml.opaque"], true ]
 
-let is_unboxed_attribute =
-  [ ["unboxed"; "ocaml.unboxed"], true ]
+let is_unboxable_attribute =
+  [ ["unboxable"; "ocaml.unboxable"], true ]
 
 let find_attribute ?mark_used p attributes =
   let inline_attribute =
@@ -591,13 +591,13 @@ let add_opaque_attribute expr loc attributes =
 let add_unbox_return_attribute expr loc attributes =
   match expr with
   | Lfunction funct ->
-      let attr = find_attribute is_unboxed_attribute attributes in
+      let attr = find_attribute is_unboxable_attribute attributes in
       begin match attr with
       | None -> expr
       | Some _ ->
           if funct.attr.unbox_return then
             Location.prerr_warning loc
-              (Warnings.Duplicated_attribute "unboxed");
+              (Warnings.Duplicated_attribute "unboxable");
           let attr = { funct.attr with unbox_return = true } in
           lfunction_with_attr ~attr funct
       end
@@ -676,8 +676,8 @@ let add_function_attributes lam loc attr =
   lam
 
 let transl_param_attributes pat =
-      let attrs = pat.pat_attributes in
-      let unbox_param =
-        Option.is_some (find_attribute is_unboxed_attribute attrs)
-      in
-      { unbox_param }
+  let attrs = pat.pat_attributes in
+  let unbox_param =
+    Option.is_some (find_attribute is_unboxable_attribute attrs)
+  in
+  { unbox_param }