use create_snapshot_for_diagnostic instead of clone for Parser

Author: TaKO8Ki

compiler/rustc_parse/src/parser/item.rs

@@ -2260,7 +2260,7 @@ impl<'a> Parser<'a> {
                 (pat, this.parse_ty_for_param()?)
             } else {
                 debug!("parse_param_general ident_to_pat");
-                let parser_snapshot_before_ty = this.clone();
+                let parser_snapshot_before_ty = this.create_snapshot_for_diagnostic();
                 this.eat_incorrect_doc_comment_for_param_type();
                 let mut ty = this.parse_ty_for_param();
                 if ty.is_ok()
@@ -2283,7 +2283,7 @@ impl<'a> Parser<'a> {
                     // Recover from attempting to parse the argument as a type without pattern.
                     Err(err) => {
                         err.cancel();
-                        *this = parser_snapshot_before_ty;
+                        this.restore_snapshot(parser_snapshot_before_ty);
                         this.recover_arg_parse()?
                     }
                 }