Make sure overload checks work for TypeAlias, see #1416

test/completion/pep0484_overload.py

@@ -0,0 +1,28 @@
+# python >= 3.4
+from typing import List, Dict, overload
+
+
+# -------------------------
+# With base classes
+# -------------------------
+
+@overload
+def overload_f2(value: List) -> str: ...
+@overload
+def overload_f2(value: Dict) -> int: ...
+
+#? str()
+overload_f2([''])
+#? int()
+overload_f2({1.0: 1.0})
+
+
+@overload
+def overload_f3(value: list) -> str: ...
+@overload
+def overload_f3(value: dict) -> float: ...
+
+#? str()
+overload_f3([''])
+#? float()
+overload_f3({1.0: 1.0})