Clone the entire stack for lexer checkpoint

crates/ruff_python_parser/src/lexer.rs

@@ -423,7 +423,7 @@ impl<'src> Lexer<'src> {
         TokenKind::Comment
     }
 
-    /// Lex a single `IPython` escape command.
+    /// Lex a single IPython escape command.
     fn lex_ipython_escape_command(&mut self, escape_kind: IpyEscapeKind) -> TokenKind {
         let mut value = String::new();
 
@@ -1341,11 +1341,6 @@ impl<'src> Lexer<'src> {
     }
 
     /// Restore the lexer to the given checkpoint.
-    ///
-    /// # Panics
-    ///
-    /// If the current indentation is less than the indentation at the checkpoint
-    /// If the lexer is out of any f-strings it was in at the time of checkpoint
     pub(crate) fn rewind(&mut self, checkpoint: LexerCheckpoint<'src>) {
         self.value = checkpoint.value;
         self.current = checkpoint.current;
@@ -1554,7 +1549,7 @@ pub(crate) enum TokenValue {
         /// and prefixes of the string
         flags: AnyStringFlags,
     },
-    /// Token value for `IPython` escape commands. These are recognized by the lexer
+    /// Token value for IPython escape commands. These are recognized by the lexer
     /// only when the mode is [`Mode::Ipython`].
     IpyEscapeCommand {
         /// The magic command value.

crates/ruff_python_parser/src/lexer/fstring.rs

@@ -1,7 +1,7 @@
 use ruff_python_ast::AnyStringFlags;
 
 /// The context representing the current f-string that the lexer is in.
-#[derive(Debug)]
+#[derive(Clone, Debug)]
 pub(crate) struct FStringContext {
     flags: AnyStringFlags,
 
@@ -129,15 +129,13 @@ impl FStrings {
     }
 
     pub(crate) fn checkpoint(&self) -> FStringsCheckpoint {
-        FStringsCheckpoint(self.stack.len())
+        FStringsCheckpoint(self.stack.clone())
     }
 
     pub(crate) fn rewind(&mut self, checkpoint: FStringsCheckpoint) {
-        assert!(self.stack.len() <= checkpoint.0);
-
-        self.stack.truncate(checkpoint.0);
+        self.stack = checkpoint.0;
     }
 }
 
-#[derive(Debug, Copy, Clone)]
-pub(crate) struct FStringsCheckpoint(usize);
+#[derive(Debug, Clone)]
+pub(crate) struct FStringsCheckpoint(Vec<FStringContext>);

crates/ruff_python_parser/src/lexer/indentation.rs

@@ -126,18 +126,16 @@ impl Indentations {
     }
 
     pub(crate) fn checkpoint(&self) -> IndentationsCheckpoint {
-        IndentationsCheckpoint(self.stack.len())
+        IndentationsCheckpoint(self.stack.clone())
     }
 
     pub(crate) fn rewind(&mut self, checkpoint: IndentationsCheckpoint) {
-        assert!(self.stack.len() <= checkpoint.0);
-
-        self.stack.truncate(checkpoint.0);
+        self.stack = checkpoint.0;
     }
 }
 
-#[derive(Debug, Copy, Clone)]
-pub(crate) struct IndentationsCheckpoint(usize);
+#[derive(Debug, Clone)]
+pub(crate) struct IndentationsCheckpoint(Vec<Indentation>);
 
 assert_eq_size!(Indentation, u64);