Auto merge of rust-lang#95068 - TaKO8Ki:use-create-snapshot-for-diagnostic, r=davidtwco

Use `Parser.create_snapshot_for_diagnostic` instead of `Parser.clone()`

Use [`create_snapshot_for_diagnostic`](https://github.com/rust-lang/rust/blob/cd119057160cedea245aa2679add56723f3dc784/compiler/rustc_parse/src/parser/diagnostics.rs#L214-L223) I implemented in rust-lang#94731 instead of `self.clone()` to avoid duplicate unclosed delims errors being emitted when the `Parser` is dropped.

Author: bors

compiler/rustc_parse/src/parser/expr.rs

@@ -1,9 +1,10 @@
+use super::diagnostics::SnapshotParser;
 use super::pat::{CommaRecoveryMode, RecoverColon, RecoverComma, PARAM_EXPECTED};
 use super::ty::{AllowPlus, RecoverQPath, RecoverReturnSign};
 use super::{
-    AttrWrapper, BlockMode, ClosureSpans, ForceCollect, Parser, PathStyle, Restrictions, TokenType,
+    AttrWrapper, BlockMode, ClosureSpans, ForceCollect, Parser, PathStyle, Restrictions,
+    SemiColonMode, SeqSep, TokenExpectType, TokenType, TrailingToken,
 };
-use super::{SemiColonMode, SeqSep, TokenExpectType, TrailingToken};
 use crate::maybe_recover_from_interpolated_ty_qpath;
 
 use ast::token::DelimToken;
@@ -1105,7 +1106,7 @@ impl<'a> Parser<'a> {
         let snapshot = if self.token.kind == token::OpenDelim(token::Paren)
             && self.look_ahead_type_ascription_as_field()
         {
-            Some((self.clone(), fun.kind.clone()))
+            Some((self.create_snapshot_for_diagnostic(), fun.kind.clone()))
         } else {
             None
         };
@@ -1130,7 +1131,7 @@ impl<'a> Parser<'a> {
         lo: Span,
         open_paren: Span,
         seq: &mut PResult<'a, P<Expr>>,
-        snapshot: Option<(Self, ExprKind)>,
+        snapshot: Option<(SnapshotParser<'a>, ExprKind)>,
     ) -> Option<P<Expr>> {
         match (seq.as_mut(), snapshot) {
             (Err(err), Some((mut snapshot, ExprKind::Path(None, path)))) => {
@@ -1140,7 +1141,7 @@ impl<'a> Parser<'a> {
                     Ok((fields, ..)) if snapshot.eat(&token::CloseDelim(token::Paren)) => {
                         // We are certain we have `Enum::Foo(a: 3, b: 4)`, suggest
                         // `Enum::Foo { a: 3, b: 4 }` or `Enum::Foo(3, 4)`.
-                        *self = snapshot;
+                        self.restore_snapshot(snapshot);
                         let close_paren = self.prev_token.span;
                         let span = lo.to(self.prev_token.span);
                         if !fields.is_empty() {