use create_snapshot_for_diagnostic instead of clone

Author: TaKO8Ki

compiler/rustc_expand/src/mbe/macro_rules.rs

@@ -123,7 +123,7 @@ impl<'a> ParserAnyMacro<'a> {
             is_trailing_mac,
             is_local,
         } = *self;
-        let snapshot = &mut parser.clone();
+        let snapshot = &mut parser.create_snapshot_for_diagnostic();
         let fragment = match parse_ast_fragment(parser, kind) {
             Ok(f) => f,
             Err(err) => {

compiler/rustc_parse/src/parser/diagnostics.rs

@@ -336,7 +336,7 @@ struct InInTypo {
 // SnapshotParser is used to create a snapshot of the parser
 // without causing duplicate errors being emitted when the `Parser`
 // is dropped.
-pub(super) struct SnapshotParser<'a> {
+pub struct SnapshotParser<'a> {
     parser: Parser<'a>,
     unclosed_delims: Vec<UnmatchedBrace>,
 }
@@ -392,7 +392,7 @@ impl<'a> Parser<'a> {
     }
 
     /// Create a snapshot of the `Parser`.
-    pub(super) fn create_snapshot_for_diagnostic(&self) -> SnapshotParser<'a> {
+    pub fn create_snapshot_for_diagnostic(&self) -> SnapshotParser<'a> {
         let mut snapshot = self.clone();
         let unclosed_delims = self.unclosed_delims.clone();
         // Clear `unclosed_delims` in snapshot to avoid