TypeAliasType: Add apostrophe to error message for compatibility with CPython (#495)

Author: Daraan

src/test_typing_extensions.py

@@ -7463,9 +7463,9 @@ def test_type_params_possibilities(self):
             (T_default, P_default, Ts_default),
         ]
         invalid_cases = [
-            ((T_default, T), f"non-default type parameter {T!r} follows default"),
-            ((P_default, P), f"non-default type parameter {P!r} follows default"),
-            ((Ts_default, T), f"non-default type parameter {T!r} follows default"),
+            ((T_default, T), f"non-default type parameter '{T!r}' follows default"),
+            ((P_default, P), f"non-default type parameter '{P!r}' follows default"),
+            ((Ts_default, T), f"non-default type parameter '{T!r}' follows default"),
             # Only type params are accepted
             ((1,), "Expected a type param, got 1"),
             ((str,), f"Expected a type param, got {str!r}"),

src/typing_extensions.py

@@ -3622,8 +3622,8 @@ def __init__(self, name: str, value, *, type_params=()):
                     getattr(type_param, '__default__', NoDefault) is not NoDefault
                 )
                 if default_value_encountered and not has_default:
-                    raise TypeError(f'non-default type parameter {type_param!r}'
-                                    ' follows default type parameter')
+                    raise TypeError(f"non-default type parameter '{type_param!r}'"
+                                    " follows default type parameter")
                 if has_default:
                     default_value_encountered = True
                 if isinstance(type_param, TypeVarTuple):