gh-144030: check that argument is callable in py version of lru_cache

Author: cfbolz

Lib/functools.py

@@ -602,6 +602,9 @@ def decorating_function(user_function):
     return decorating_function
 
 def _lru_cache_wrapper(user_function, maxsize, typed, _CacheInfo):
+    if not callable(user_function):
+        raise TypeError("the first argument must be callable")
+
     # Constants shared by all lru cache instances:
     sentinel = object()          # unique object used to signal cache misses
     make_key = _make_key         # build a key from the function arguments

Lib/test/test_functools.py

@@ -2157,6 +2157,11 @@ def fib(n):
                 with self.assertRaises(RecursionError):
                     fib(support.exceeds_recursion_limit())
 
+    def test_lru_checks_arg_is_callable(self):
+        with self.assertRaises(TypeError) as te:
+            self.module.lru_cache(1)('hello')
+        self.assertIn("the first argument must be callable", str(te.exception))
+
 
 @py_functools.lru_cache()
 def py_cached_func(x, y):