Fix type eval if params are not in alphabetical order. (#23)

Fixes `type X[B, A] = A`

Author: dnwpark

tests/test_type_eval.py

@@ -134,6 +134,17 @@ class TB:
     y: list[object]
 
 
+type GetA1[A, B] = A
+type GetA2[B, A] = A
+
+
+def test_eval_arg_order():
+    d = eval_typing(GetA1[int, str])
+    assert d is int
+    d = eval_typing(GetA2[str, int])
+    assert d is int
+
+
 def test_type_getattr_union_1():
     d = eval_typing(GetAttr[TA | TB, Literal["x"]])
     assert d == int | str
@@ -640,7 +651,7 @@ def test_never_is():
     assert d is True
 
 
-def test_eval_iter():
+def test_eval_iter_01():
     d = eval_typing(Iter[tuple[int, str]])
     assert tuple(d) == (int, str)
 

typemap/type_eval/_eval_typing.py

@@ -298,7 +298,20 @@ def _eval_applied_type_alias(obj: types.GenericAlias, ctx: EvalContext):
 
     func = obj.evaluate_value
 
-    args = tuple(types.CellType(_eval_types(arg, ctx)) for arg in obj.__args__)
+    # obj.__args__ matches the declared parameter order, but args are expected
+    # to be in the same order as func.__code__.co_freevars.
+    args_by_name = dict(
+        zip(
+            (p.__name__ for p in obj.__origin__.__type_params__),
+            obj.__args__,
+            strict=False,
+        )
+    )
+
+    args = tuple(
+        types.CellType(_eval_types(args_by_name[name], ctx))
+        for name in func.__code__.co_freevars
+    )
     mod = sys.modules[obj.__module__]
 
     with _child_context() as child_ctx: