Add another bugfix and test

crates/red_knot_python_semantic/src/semantic_index/builder.rs

@@ -753,6 +753,14 @@ where
                     self.flow_merge(state);
                 }
                 let pre_except_state = self.flow_snapshot();
+
+                // Account for the fact that we could be visiting a nested `try` block,
+                // in which case the outer `try` block must be kept informed about all the possible
+                // between-definition states we could have encountered in the inner `try` block(!)
+                if self.visiting_try_block {
+                    self.try_block_definition_states.push(self.flow_snapshot());
+                }
+
                 let mut post_except_states = vec![];
                 let num_handlers = handlers.len();
 

crates/red_knot_python_semantic/src/types/infer.rs

@@ -4939,6 +4939,37 @@ mod tests {
         Ok(())
     }
 
+    #[test]
+    fn exception_raised_in_nested_try_block_caught_in_outer() -> anyhow::Result<()> {
+        let mut db = setup_db();
+
+        db.write_dedented(
+            "src/a.py",
+            "
+            try:
+                try:
+                    x = 1
+                    x = 2
+                except TypeError:
+                    x = 3
+                else:
+                    x = 4
+            except:
+                pass
+            ",
+        )?;
+
+        assert_file_diagnostics(&db, "src/a.py", &[]);
+
+        // We might have left the inner `try` or the inner `except TypeError`
+        // block due to another exception, in which case the assignments in the inner `try` block
+        // would not necessarily have been overridden by the otherwise-exhaustive
+        // `except`/`else` branches in the inner block.
+        assert_public_ty(&db, "src/a.py", "x", "Unbound | Literal[1, 2, 3, 4]");
+
+        Ok(())
+    }
+
     #[test]
     fn basic_comprehension() -> anyhow::Result<()> {
         let mut db = setup_db();