avoid byte slicing in dotdotdot rest pattern suggestion

Author: TaKO8Ki

compiler/rustc_parse/src/errors.rs

@@ -3238,7 +3238,7 @@ pub(crate) struct DotDotDotRestPattern {
     #[suggestion(
         "for a rest pattern, use `..` instead of `...`",
         style = "verbose",
-        code = "",
+        code = "..",
         applicability = "machine-applicable"
     )]
     pub suggestion: Option<Span>,

compiler/rustc_parse/src/parser/pat.rs

@@ -920,7 +920,7 @@ impl<'a> Parser<'a> {
             // The user probably mistook `...` for a rest pattern `..`.
             self.dcx().emit_err(DotDotDotRestPattern {
                 span: lo,
-                suggestion: Some(lo.with_lo(lo.hi() - BytePos(1))),
+                suggestion: Some(lo),
                 var_args: None,
             });
             PatKind::Rest