Fix a false positive for consider-using-dict-items

doc/whatsnew/fragments/9554.false_positive

@@ -0,0 +1,3 @@
+Fix a false positive for ``consider-using-dict-items`` when iterating ``os.environ`` using the ``os.environ.keys()`` operation and then deleting an item using the key as a lookup.
+
+Closes #9554

pylint/checkers/refactoring/recommendation_checker.py

@@ -308,6 +308,10 @@ def _check_consider_using_dict_items(self, node: nodes.For) -> None:
                     # Ignore this subscript if it is the target of an assignment
                     # Early termination as dict index lookup is necessary
                     return
+                if isinstance(subscript.parent, nodes.Delete):
+                    # Ignore this subscript if the index is used to delete a
+                    # dictionary item.
+                    return
 
                 self.add_message("consider-using-dict-items", node=node)
                 return

tests/functional/c/consider/consider_using_dict_items.py

@@ -1,5 +1,6 @@
 """Emit a message for iteration through dict keys and subscripting dict with key."""
 # pylint: disable=line-too-long,missing-docstring,unsubscriptable-object,too-few-public-methods,redefined-outer-name,use-dict-literal,modified-iterating-dict
+# pylint: disable=wrong-import-position
 
 def bad():
     a_dict = {1: 1, 2: 2, 3: 3}
@@ -103,3 +104,11 @@ class Foo:
 for k in d:  # [consider-using-dict-items]
     if '1' in d[k]:  # index lookup necessary here, do not emit error
         print('found 1')
+
+
+# False positive in issue #9554
+# https://github.com/pylint-dev/pylint/issues/9554
+import os
+for var in os.environ.keys():  # [consider-iterating-dictionary]
+    if var.startswith('foo_'):
+        del os.environ[var]  # index lookup necessary here, do not emit error

tests/functional/c/consider/consider_using_dict_items.txt

@@ -1,16 +1,17 @@
-consider-using-dict-items:6:4:7:24:bad:Consider iterating with .items():UNDEFINED
-consider-using-dict-items:9:4:10:30:bad:Consider iterating with .items():UNDEFINED
-consider-using-dict-items:21:4:22:35:another_bad:Consider iterating with .items():UNDEFINED
-consider-using-dict-items:40:0:42:18::Consider iterating with .items():UNDEFINED
-consider-using-dict-items:44:0:45:20::Consider iterating with .items():UNDEFINED
-consider-iterating-dictionary:47:10:47:23::Consider iterating the dictionary directly instead of calling .keys():INFERENCE
-consider-using-dict-items:47:0:48:20::Consider iterating with .items():UNDEFINED
-consider-using-dict-items:54:0:55:24::Consider iterating with .items():UNDEFINED
-consider-using-dict-items:67:0:None:None::Consider iterating with .items():UNDEFINED
+consider-using-dict-items:7:4:8:24:bad:Consider iterating with .items():UNDEFINED
+consider-using-dict-items:10:4:11:30:bad:Consider iterating with .items():UNDEFINED
+consider-using-dict-items:22:4:23:35:another_bad:Consider iterating with .items():UNDEFINED
+consider-using-dict-items:41:0:43:18::Consider iterating with .items():UNDEFINED
+consider-using-dict-items:45:0:46:20::Consider iterating with .items():UNDEFINED
+consider-iterating-dictionary:48:10:48:23::Consider iterating the dictionary directly instead of calling .keys():INFERENCE
+consider-using-dict-items:48:0:49:20::Consider iterating with .items():UNDEFINED
+consider-using-dict-items:55:0:56:24::Consider iterating with .items():UNDEFINED
 consider-using-dict-items:68:0:None:None::Consider iterating with .items():UNDEFINED
-consider-using-dict-items:71:0:None:None::Consider iterating with .items():UNDEFINED
+consider-using-dict-items:69:0:None:None::Consider iterating with .items():UNDEFINED
 consider-using-dict-items:72:0:None:None::Consider iterating with .items():UNDEFINED
-consider-using-dict-items:75:0:None:None::Consider iterating with .items():UNDEFINED
-consider-iterating-dictionary:86:25:86:42::Consider iterating the dictionary directly instead of calling .keys():INFERENCE
-consider-using-dict-items:86:0:None:None::Consider iterating with .items():UNDEFINED
-consider-using-dict-items:103:0:105:24::Consider iterating with .items():UNDEFINED
+consider-using-dict-items:73:0:None:None::Consider iterating with .items():UNDEFINED
+consider-using-dict-items:76:0:None:None::Consider iterating with .items():UNDEFINED
+consider-iterating-dictionary:87:25:87:42::Consider iterating the dictionary directly instead of calling .keys():INFERENCE
+consider-using-dict-items:87:0:None:None::Consider iterating with .items():UNDEFINED
+consider-using-dict-items:104:0:106:24::Consider iterating with .items():UNDEFINED
+consider-iterating-dictionary:112:11:112:28::Consider iterating the dictionary directly instead of calling .keys():INFERENCE