Port identity function to rust

rust_src/src/lib.rs

@@ -200,6 +200,9 @@ pub use editfns::Feolp;
 // Used in minibuffer.c
 pub use windows::Fwindow_minibuffer_p;
 
+// Used in term.c, dired.c
+pub use objects::Fidentity;
+
 extern "C" {
     fn defsubr(sname: *const Lisp_Subr);
 }
@@ -266,6 +269,7 @@ pub extern "C" fn rust_init_syms() {
         defsubr(&*objects::Seql);
         defsubr(&*objects::Sequal);
         defsubr(&*objects::Sequal_including_properties);
+        defsubr(&*objects::Sidentity);
         defsubr(&*symbols::Ssymbolp);
         defsubr(&*symbols::Ssymbol_name);
         defsubr(&*symbols::Sfboundp);

rust_src/src/objects.rs

@@ -52,3 +52,9 @@ fn equal_including_properties(o1: LispObject, o2: LispObject) -> LispObject {
     };
     LispObject::from_bool(res)
 }
+
+/// Return the argument unchanged.
+#[lisp_fn]
+fn identity(arg: LispObject) -> LispObject {
+    arg
+}

src/fns.c

@@ -44,14 +44,6 @@ along with GNU Emacs.  If not, see <https://www.gnu.org/licenses/>.  */
 enum equal_kind { EQUAL_NO_QUIT, EQUAL_PLAIN, EQUAL_INCLUDING_PROPERTIES };
 bool internal_equal (Lisp_Object, Lisp_Object, enum equal_kind, int, Lisp_Object);
 
-DEFUN ("identity", Fidentity, Sidentity, 1, 1, 0,
-       doc: /* Return the argument unchanged.  */
-       attributes: const)
-  (Lisp_Object arg)
-{
-  return arg;
-}
-
 /* Random data-structure functions.  */
 
 DEFUN ("compare-strings", Fcompare_strings, Scompare_strings, 6, 7, 0,
@@ -3854,7 +3846,6 @@ that disables the use of a file dialog, regardless of the value of
 this variable.  */);
   use_file_dialog = 1;
 
-  defsubr (&Sidentity);
   defsubr (&Scompare_strings);
   defsubr (&Sstring_version_lessp);
   defsubr (&Sstring_collate_lessp);