Rename cache-max-size-none and check functools.cache (pylint-…

…dev#6182)

Co-authored-by: Pierre Sassoulas <pierre.sassoulas@gmail.com>

ChangeLog

@@ -141,6 +141,14 @@ Release date: TBA
 
   Closes #5936
 
+* The ``cache-max-size-none`` checker has been renamed to ``method-cache-max-size-none``.
+
+  Closes #5670
+
+* The ``method-cache-max-size-none`` checker will now also check ``functools.cache``.
+
+  Closes #5670
+
 * ``potential-index-error``: Emitted when the index of a list or tuple exceeds its length.
   This checker is currently quite conservative to avoid false positives. We welcome
   suggestions for improvements.

doc/data/messages/m/method-cache-max-size-none/bad.py

@@ -0,0 +1,9 @@
+import functools
+
+
+class Fibonnaci:
+    @functools.lru_cache(maxsize=None)  # [method-cache-max-size-none]
+    def fibonacci(self, n):
+        if n in {0, 1}:
+            return n
+        return self.fibonacci(n - 1) + self.fibonacci(n - 2)

doc/data/messages/m/method-cache-max-size-none/good.py

@@ -0,0 +1,13 @@
+import functools
+
+
+@functools.cache
+def cached_fibonacci(n):
+    if n in {0, 1}:
+        return n
+    return cached_fibonacci(n - 1) + cached_fibonacci(n - 2)
+
+
+class Fibonnaci:
+    def fibonacci(self, n):
+        return cached_fibonacci(n)

doc/whatsnew/2.14.rst

@@ -176,6 +176,14 @@ Other Changes
 
 * The concept of checker priority has been removed.
 
+* The ``cache-max-size-none`` checker has been renamed to ``method-cache-max-size-none``.
+
+  Closes #5670
+
+* The ``method-cache-max-size-none`` checker will now also check ``functools.cache``.
+
+  Closes #5670
+
 * ``BaseChecker`` classes now require the ``linter`` argument to be passed.
 
 * The ``set_config_directly`` decorator has been removed.

pylint/checkers/stdlib.py

@@ -420,15 +420,20 @@ class StdlibChecker(DeprecatedMixin, BaseChecker):
             "Calls to breakpoint(), sys.breakpointhook() and pdb.set_trace() should be removed "
             "from code that is not actively being debugged.",
         ),
-        "W1517": (
-            "'lru_cache(maxsize=None)' will keep all method args alive indefinitely, including 'self'",
-            "cache-max-size-none",
-            "By decorating a method with lru_cache the 'self' argument will be linked to "
-            "the lru_cache function and therefore never garbage collected. Unless your instance "
+        "W1518": (
+            "'lru_cache(maxsize=None)' or 'cache' will keep all method args alive indefinitely, including 'self'",
+            "method-cache-max-size-none",
+            "By decorating a method with lru_cache or cache the 'self' argument will be linked to "
+            "the function and therefore never garbage collected. Unless your instance "
             "will never need to be garbage collected (singleton) it is recommended to refactor "
             "code to avoid this pattern or add a maxsize to the cache."
             "The default value for maxsize is 128.",
-            {"old_names": [("W1516", "lru-cache-decorating-method")]},
+            {
+                "old_names": [
+                    ("W1516", "lru-cache-decorating-method"),
+                    ("W1517", "cache-max-size-none"),
+                ]
+            },
         ),
     }
 
@@ -551,7 +556,7 @@ def visit_boolop(self, node: nodes.BoolOp) -> None:
         for value in node.values:
             self._check_datetime(value)
 
-    @utils.check_messages("cache-max-size-none")
+    @utils.check_messages("method-cache-max-size-none")
     def visit_functiondef(self, node: nodes.FunctionDef) -> None:
         if node.decorators and isinstance(node.parent, nodes.ClassDef):
             self._check_lru_cache_decorators(node.decorators)
@@ -563,28 +568,32 @@ def _check_lru_cache_decorators(self, decorators: nodes.Decorators) -> None:
             try:
                 for infered_node in d_node.infer():
                     q_name = infered_node.qname()
-                    if q_name in NON_INSTANCE_METHODS or q_name not in LRU_CACHE:
+                    if q_name in NON_INSTANCE_METHODS:
                         return
 
                     # Check if there is a maxsize argument set to None in the call
-                    if isinstance(d_node, nodes.Call):
+                    if q_name in LRU_CACHE and isinstance(d_node, nodes.Call):
                         try:
                             arg = utils.get_argument_from_call(
                                 d_node, position=0, keyword="maxsize"
                             )
                         except utils.NoSuchArgumentError:
-                            return
+                            break
 
                         if not isinstance(arg, nodes.Const) or arg.value is not None:
-                            return
+                            break
 
-                    lru_cache_nodes.append(d_node)
-                    break
+                        lru_cache_nodes.append(d_node)
+                        break
+
+                    if q_name == "functools.cache":
+                        lru_cache_nodes.append(d_node)
+                        break
             except astroid.InferenceError:
                 pass
         for lru_cache_node in lru_cache_nodes:
             self.add_message(
-                "cache-max-size-none",
+                "method-cache-max-size-none",
                 node=lru_cache_node,
                 confidence=interfaces.INFERENCE,
             )

pylint/message/message_definition_store.py

@@ -55,7 +55,7 @@ def register_message(self, message: MessageDefinition) -> None:
     # and the arguments are relatively small in size we do not run the
     # risk of creating a large memory leak.
     # See discussion in: https://github.com/PyCQA/pylint/pull/5673
-    @functools.lru_cache(maxsize=None)  # pylint: disable=cache-max-size-none
+    @functools.lru_cache(maxsize=None)  # pylint: disable=method-cache-max-size-none
     def get_message_definitions(self, msgid_or_symbol: str) -> list[MessageDefinition]:
         """Returns the Message definition for either a numeric or symbolic id.
 

tests/functional/c/cache_max_size_none.py → tests/functional/m/method_cache_max_size_none.py

@@ -1,4 +1,4 @@
-"""Tests for cache-max-size-none"""
+"""Tests for method-cache-max-size-none"""
 # pylint: disable=no-self-use, missing-function-docstring, reimported, too-few-public-methods
 # pylint: disable=missing-class-docstring, function-redefined
 
@@ -22,25 +22,25 @@ def my_func(self, param):
     def my_func(self, param):
         return param + 1
 
-    @lru_cache(None)  # [cache-max-size-none]
+    @lru_cache(None)  # [method-cache-max-size-none]
     def my_func(self, param):
         return param + 1
 
-    @functools.lru_cache(None)  # [cache-max-size-none]
+    @functools.lru_cache(None)  # [method-cache-max-size-none]
     def my_func(self, param):
         return param + 1
 
-    @aliased_functools.lru_cache(None)  # [cache-max-size-none]
+    @aliased_functools.lru_cache(None)  # [method-cache-max-size-none]
     def my_func(self, param):
         return param + 1
 
-    @aliased_cache(None)  # [cache-max-size-none]
+    @aliased_cache(None)  # [method-cache-max-size-none]
     def my_func(self, param):
         return param + 1
 
     # Check double decorating to check robustness of checker itself
-    @aliased_cache(None)  # [cache-max-size-none]
-    @aliased_cache(None)  # [cache-max-size-none]
+    @aliased_cache(None)  # [method-cache-max-size-none]
+    @aliased_cache(None)  # [method-cache-max-size-none]
     def my_func(self, param):
         return param + 1
 
@@ -70,6 +70,11 @@ def my_func(self, param):
     def my_func(self, param):
         return param + 1
 
-    @lru_cache(typed=True, maxsize=None)  # [cache-max-size-none]
+    @lru_cache(typed=True, maxsize=None)  # [method-cache-max-size-none]
     def my_func(self, param):
         return param + 1
+
+
+@lru_cache(maxsize=None)
+def my_func(param):
+    return param + 1

tests/functional/m/method_cache_max_size_none.txt

@@ -0,0 +1,7 @@
+method-cache-max-size-none:25:5:25:20:MyClassWithMethods.my_func:'lru_cache(maxsize=None)' or 'cache' will keep all method args alive indefinitely, including 'self':INFERENCE
+method-cache-max-size-none:29:5:29:30:MyClassWithMethods.my_func:'lru_cache(maxsize=None)' or 'cache' will keep all method args alive indefinitely, including 'self':INFERENCE
+method-cache-max-size-none:33:5:33:38:MyClassWithMethods.my_func:'lru_cache(maxsize=None)' or 'cache' will keep all method args alive indefinitely, including 'self':INFERENCE
+method-cache-max-size-none:37:5:37:24:MyClassWithMethods.my_func:'lru_cache(maxsize=None)' or 'cache' will keep all method args alive indefinitely, including 'self':INFERENCE
+method-cache-max-size-none:42:5:42:24:MyClassWithMethods.my_func:'lru_cache(maxsize=None)' or 'cache' will keep all method args alive indefinitely, including 'self':INFERENCE
+method-cache-max-size-none:43:5:43:24:MyClassWithMethods.my_func:'lru_cache(maxsize=None)' or 'cache' will keep all method args alive indefinitely, including 'self':INFERENCE
+method-cache-max-size-none:73:5:73:40:MyClassWithMethodsAndMaxSize.my_func:'lru_cache(maxsize=None)' or 'cache' will keep all method args alive indefinitely, including 'self':INFERENCE

tests/functional/m/method_cache_max_size_none_py39.py

@@ -0,0 +1,47 @@
+"""Tests for method-cache-max-size-none"""
+# pylint: disable=no-self-use, missing-function-docstring, reimported, too-few-public-methods
+# pylint: disable=missing-class-docstring, function-redefined
+
+import functools
+import functools as aliased_functools
+from functools import cache
+from functools import cache as aliased_cache
+
+
+@cache
+def my_func(param):
+    return param + 1
+
+
+class MyClassWithMethods:
+    @cache
+    @staticmethod
+    def my_func(param):
+        return param + 1
+
+    @cache
+    @classmethod
+    def my_func(cls, param):
+        return param + 1
+
+    @cache  # [method-cache-max-size-none]
+    def my_func(self, param):
+        return param + 1
+
+    @functools.cache  # [method-cache-max-size-none]
+    def my_func(self, param):
+        return param + 1
+
+    @aliased_functools.cache  # [method-cache-max-size-none]
+    def my_func(self, param):
+        return param + 1
+
+    @aliased_cache  # [method-cache-max-size-none]
+    def my_func(self, param):
+        return param + 1
+
+    # Check double decorating to check robustness of checker itself
+    @functools.lru_cache(maxsize=1)
+    @aliased_cache  # [method-cache-max-size-none]
+    def my_func(self, param):
+        return param + 1

tests/functional/m/method_cache_max_size_none_py39.rc

@@ -0,0 +1,2 @@
+[testoptions]
+min_pyver = 3.9

tests/functional/m/method_cache_max_size_none_py39.txt

@@ -0,0 +1,5 @@
+method-cache-max-size-none:27:5:27:10:MyClassWithMethods.my_func:'lru_cache(maxsize=None)' or 'cache' will keep all method args alive indefinitely, including 'self':INFERENCE
+method-cache-max-size-none:31:5:31:20:MyClassWithMethods.my_func:'lru_cache(maxsize=None)' or 'cache' will keep all method args alive indefinitely, including 'self':INFERENCE
+method-cache-max-size-none:35:5:35:28:MyClassWithMethods.my_func:'lru_cache(maxsize=None)' or 'cache' will keep all method args alive indefinitely, including 'self':INFERENCE
+method-cache-max-size-none:39:5:39:18:MyClassWithMethods.my_func:'lru_cache(maxsize=None)' or 'cache' will keep all method args alive indefinitely, including 'self':INFERENCE
+method-cache-max-size-none:45:5:45:18:MyClassWithMethods.my_func:'lru_cache(maxsize=None)' or 'cache' will keep all method args alive indefinitely, including 'self':INFERENCE