[ty] Include inferred type in invalid-key concise diagnostic for union/intersection TypedDicts (#24693)

tonyxwz · web-flow · commit e73d952e43fe · 2026-04-24T17:58:17.000+02:00
## Summary Closes astral-sh/ty#3271 When subscripting a union or intersection of TypedDicts with an invalid key, the concise diagnostic message now includes the source expression and its full inferred type. This lets programmatic consumers of ty's output distinguish between: 1. Key invalid on one branch of a union — may be intentional (e.g. probing for a key that only exists on some branches) 2. Key truly invalid on a single-typed variable — likely a bug ### Before ``` file.py:19:14: error[invalid-key] Unknown key "foo" for TypedDict `DictB` file.py:22:14: error[invalid-key] Unknown key "bar" for TypedDict `DictA` ``` Both errors look identical in structure — there is no way to tell from concise output that line 19 involves a union type while line 22 does not. ### After ``` file.py:19:14: error[invalid-key] Unknown key "foo" for TypedDict `DictB` (`resp` has type `DictA | DictB`) file.py:22:14: error[invalid-key] Unknown key "bar" for TypedDict `DictA` ``` The source expression name is used (e.g. `resp`, `obj.data`), making the message immediately understandable. The full (non-concise) diagnostic output is unchanged — it already showed the union/intersection context via a secondary annotation. ## Test Plan - Updated 3 existing mdtest assertions in `typed_dict.md` to verify the new concise message format for union and intersection cases - All 330 tests in `ty_python_semantic` pass - Clippy clean - Manually verified concise output on the reproduction from the linked issue
diff --git a/crates/ty_python_semantic/resources/mdtest/typed_dict.md b/crates/ty_python_semantic/resources/mdtest/typed_dict.md
@@ -1873,7 +1873,7 @@ def _(
 
     reveal_type(being["name"])  # revealed: str
 
-    # error: [invalid-key] "Unknown key "age" for TypedDict `Animal`"
+    # error: [invalid-key] "Unknown key "age" for TypedDict `Animal` (subscripted object has type `Person | Animal`)"
     reveal_type(being["age"])  # revealed: int | None | Unknown
 
     # error: [invalid-key]
@@ -1928,15 +1928,15 @@ def _(being: Person | Animal):
     # error: [invalid-assignment] "Invalid assignment to key "name" with declared type `str` on TypedDict `Animal`: value of type `Literal[1]`"
     being["name"] = 1
 
-    # error: [invalid-key] "Unknown key "leg" for TypedDict `Animal`"
+    # error: [invalid-key] "Unknown key "leg" for TypedDict `Animal` (subscripted object has type `Person | Animal`)"
     being["leg"] = "unknown"
 
 def _(centaur: Intersection[Person, Animal]):
     centaur["name"] = "Chiron"
     centaur["age"] = 100
     centaur["legs"] = 4
 
-    # error: [invalid-key] "Unknown key "unknown" for TypedDict `Person`"
+    # error: [invalid-key] "Unknown key "unknown" for TypedDict `Person` (subscripted object has type `Person & Animal`)"
     centaur["unknown"] = "value"
 
 def _(person: Person, union_of_keys: Literal["name", "age"], unknown_value: Any):
diff --git a/crates/ty_python_semantic/src/types/diagnostic.rs b/crates/ty_python_semantic/src/types/diagnostic.rs
@@ -5248,9 +5248,16 @@ pub(crate) fn report_invalid_key_on_typed_dict<'db>(
                     ));
                 } else {
                     diagnostic.set_primary_message(format_args!("Unknown key \"{key}\""));
-                    diagnostic.set_concise_message(format_args!(
-                        "Unknown key \"{key}\" for TypedDict `{typed_dict_name}`",
-                    ));
+                    if let Some(full_ty) = full_object_ty {
+                        diagnostic.set_concise_message(format_args!(
+                            "Unknown key \"{key}\" for TypedDict `{typed_dict_name}` (subscripted object has type `{full_ty}`)",
+                            full_ty = full_ty.display(db),
+                        ));
+                    } else {
+                        diagnostic.set_concise_message(format_args!(
+                            "Unknown key \"{key}\" for TypedDict `{typed_dict_name}`",
+                        ));
+                    }
                 }
             }
             _ => {
