Sync interpolated lexer state within `re_lex_logical_token`

crates/ruff_python_ast/src/token.rs

@@ -841,7 +841,7 @@ impl TokenFlags {
         self.intersects(TokenFlags::T_STRING.union(TokenFlags::F_STRING))
     }
 
-    /// Returns `true` if the token is a triple-quoted t-string.
+    /// Returns `true` if the token is a triple-quoted interpolated-string.
     pub fn is_triple_quoted_interpolated_string(self) -> bool {
         self.intersects(TokenFlags::TRIPLE_QUOTED_STRING) && self.is_interpolated_string()
     }

crates/ruff_python_parser/src/lexer.rs

@@ -1452,14 +1452,20 @@ impl<'src> Lexer<'src> {
             return false;
         }
 
+        if let Some(interpolated) = self.interpolated_strings.current_mut() {
+            interpolated.try_end_format_spec(self.nesting);
+        }
+
         // Reduce the nesting level because the parser recovered from an error inside list parsing
         // i.e., it recovered from an unclosed parenthesis (`(`, `[`, or `{`).
         self.nesting -= 1;
 
-        // The lexer can't be moved back for a triple-quoted f/t-string because the newlines are
+        // A nesting level that's lower than the nesting when the interpolated string was created
-        // part of the f/t-string itself, so there is no newline token to be emitted.
+        // strongly suggests that we're now outside an interpolated string.
-        if self.current_flags.is_triple_quoted_interpolated_string() {
+        if let Some(interpolated) = self.interpolated_strings.current()
-            return false;
+            && interpolated.nesting() < self.nesting
+        {
+            self.interpolated_strings.pop();
         }
 
         let Some(new_position) = non_logical_newline_start else {
@@ -1537,6 +1543,8 @@ impl<'src> Lexer<'src> {
             }
         }
 
+        dbg!("Handle unclosed string");
+
         if self.errors.last().is_some_and(|error| {
             error.location() == self.current_range
                 && matches!(error.error(), LexicalErrorType::UnclosedStringError)

crates/ruff_python_parser/tests/snapshots/invalid_syntax@re_lexing__ty_1828.py.snap

@@ -145,6 +145,28 @@ Module(
                     simple: false,
                 },
             ),
+            ClassDef(
+                StmtClassDef {
+                    node_index: NodeIndex(None),
+                    range: 94..111,
+                    decorator_list: [],
+                    name: Identifier {
+                        id: Name("A"),
+                        range: 100..101,
+                        node_index: NodeIndex(None),
+                    },
+                    type_params: None,
+                    arguments: None,
+                    body: [
+                        Pass(
+                            StmtPass {
+                                node_index: NodeIndex(None),
+                                range: 107..111,
+                            },
+                        ),
+                    ],
+                },
+            ),
         ],
     },
 )
@@ -189,17 +211,6 @@ Module(
   |
 
 
-  |
-1 |   # Regression test for https://github.com/astral-sh/ty/issues/1828
-2 |   (c: int = 1,f"""{d=[
-3 |   def a(
-  |  _______^
-4 | | class A:
-5 | |     pass
-  | |_________^ Syntax Error: f-string: unterminated triple-quoted string
-  |
-
-
   |
 2 | (c: int = 1,f"""{d=[
 3 | def a(
@@ -209,17 +220,6 @@ Module(
   |
 
 
-  |
-1 |   # Regression test for https://github.com/astral-sh/ty/issues/1828
-2 |   (c: int = 1,f"""{d=[
-3 |   def a(
-  |  _______^
-4 | | class A:
-5 | |     pass
-  | |_________^ Syntax Error: Expected a statement
-  |
-
-
   |
 4 | class A:
 5 |     pass