[ty] Fix completion in decorator without class or function definition

crates/ruff_python_parser/src/parser/statement.rs

@@ -2914,21 +2914,27 @@ impl<'src> Parser<'src> {
                     self.current_token_range(),
                 );
 
-                // TODO(dhruvmanila): It seems that this recovery drops all the parsed
-                // decorators. Maybe we could convert them into statement expression
-                // with a flag indicating that this expression is part of a decorator.
-                // It's only possible to keep them if it's a function or class definition.
-                // We could possibly keep them if there's indentation error:
-                //
-                // ```python
-                // @decorator
-                //   @decorator
-                // def foo(): ...
-                // ```
-                //
-                // Or, parse it as a binary expression where the left side is missing.
-                // We would need to convert each decorator into a binary expression.
-                self.parse_statement()
+                let range = self.node_range(start);
+
+                ast::StmtFunctionDef {
+                    node_index: Default::default(),
+                    range,
+                    is_async: false,
+                    decorator_list: decorators,
+                    name: ast::Identifier {
+                        id: Name::empty(),
+                        range: self.missing_node_range(),
+                        node_index: AtomicNodeIndex::NONE,
+                    },
+                    type_params: None,
+                    parameters: Box::new(ast::Parameters {
+                        range: self.missing_node_range(),
+                        ..ast::Parameters::default()
+                    }),
+                    returns: None,
+                    body: vec![],
+                }
+                .into()
             }
         }
     }