bpo-42345: Fix three issues with typing.Literal parameters

Lib/test/test_typing.py

@@ -559,6 +559,20 @@ def test_no_multiple_subscripts(self):
         with self.assertRaises(TypeError):
             Literal[1][1]
 
+    def test_equal(self):
+        self.assertNotEqual(Literal[0], Literal[False])
+        self.assertNotEqual(Literal[True], Literal[1])
+        self.assertNotEqual(Literal[1], Literal[2])
+        self.assertNotEqual(Literal[1, True], Literal[1])
+        self.assertEqual(Literal[1], Literal[1])
+        self.assertEqual(Literal[1, 2], Literal[2, 1])
+        self.assertEqual(Literal[1, 2, 3], Literal[1, 2, 3, 3])
+
+    def test_flatten(self):
+        self.assertEqual(Literal[Literal[1], Literal[2], Literal[3]], Literal[1, 2, 3])
+        self.assertEqual(Literal[Literal[1, 2], 3], Literal[1, 2, 3])
+        self.assertEqual(Literal[Literal[1, 2, 3]], Literal[1, 2, 3])
+
 
 XK = TypeVar('XK', str, bytes)
 XV = TypeVar('XV')

Lib/typing.py

@@ -228,25 +228,41 @@ def _remove_dups_flatten(parameters):
     return tuple(params)
 
 
+def _flatten_literal_params(parameters):
+    """An internal helper for Literal creation: flatten Literals among parameters"""
+    params = []
+    for p in parameters:
+        if isinstance(p, _LiteralGenericAlias):
+            params.extend(p.__args__)
+        else:
+            params.append(p)
+    return tuple(params)
+
+
 _cleanups = []
 
 
-def _tp_cache(func):
+def _tp_cache(typed=False):
     """Internal wrapper caching __getitem__ of generic types with a fallback to
     original function for non-hashable arguments.
     """
-    cached = functools.lru_cache()(func)
-    _cleanups.append(cached.cache_clear)
+    if callable(typed):
+        return _tp_cache()(typed)
 
-    @functools.wraps(func)
-    def inner(*args, **kwds):
-        try:
-            return cached(*args, **kwds)
-        except TypeError:
-            pass  # All real errors (not unhashable args) are raised below.
-        return func(*args, **kwds)
-    return inner
+    def decorator(func):
+        cached = functools.lru_cache(typed=typed)(func)
+        _cleanups.append(cached.cache_clear)
 
+        @functools.wraps(func)
+        def inner(*args, **kwds):
+            try:
+                return cached(*args, **kwds)
+            except TypeError:
+                pass  # All real errors (not unhashable args) are raised below.
+            return func(*args, **kwds)
+        return inner
+
+    return decorator
 
 def _eval_type(t, globalns, localns, recursive_guard=frozenset()):
     """Evaluate all forward references in the given type t.
@@ -319,6 +335,13 @@ def __subclasscheck__(self, cls):
     def __getitem__(self, parameters):
         return self._getitem(self, parameters)
 
+
+class _LiteralSpecialForm(_SpecialForm, _root=True):
+    @_tp_cache(typed=True)
+    def __getitem__(self, parameters):
+        return self._getitem(self, parameters)
+
+
 @_SpecialForm
 def Any(self, parameters):
     """Special type indicating an unconstrained type.
@@ -436,7 +459,7 @@ def Optional(self, parameters):
     arg = _type_check(parameters, f"{self} requires a single type.")
     return Union[arg, type(None)]
 
-@_SpecialForm
+@_LiteralSpecialForm
 def Literal(self, parameters):
     """Special typing form to define literal types (a.k.a. value types).
 
@@ -460,7 +483,11 @@ def open_helper(file: str, mode: MODE) -> str:
     """
     # There is no '_type_check' call because arguments to Literal[...] are
     # values, not types.
-    return _GenericAlias(self, parameters)
+    if not isinstance(parameters, tuple):
+        parameters = (parameters,)
+
+    parameters = _flatten_literal_params(parameters)
+    return _LiteralGenericAlias(self, parameters)
 
 
 @_SpecialForm
@@ -930,6 +957,21 @@ def __subclasscheck__(self, cls):
                 return True
 
 
+def _value_and_type_iter(parameters):
+    return ((p, type(p)) for p in parameters)
+
+
+class _LiteralGenericAlias(_GenericAlias, _root=True):
+
+    def __eq__(self, other):
+        if not isinstance(other, _LiteralGenericAlias):
+            return NotImplemented
+
+        return set(_value_and_type_iter(self.__args__)) == set(_value_and_type_iter(other.__args__))
+
+    def __hash__(self):
+        return hash(tuple(_value_and_type_iter(self.__args__)))
+
 
 class Generic:
     """Abstract base class for generic types.

Misc/ACKS

@@ -861,6 +861,7 @@ Jan Kanis
 Rafe Kaplan
 Jacob Kaplan-Moss
 Allison Kaptur
+Yurii Karabas
 Janne Karila
 Per Øyvind Karlsen
 Anton Kasyanov

Misc/NEWS.d/next/Library/2020-11-15-15-23-34.bpo-42345.hiIR7x.rst

@@ -0,0 +1,2 @@
+Fix ``typing.Literal`` equals method to ignore the order of arguments.
+Patch provided by Yurii Karabas.