Add new checker `kwarg-superseded-by-positional-arg` and fix a false positive (#8644)

* Fix a false positive for ``redundant-keyword-arg`` when a function, with a keyword-only-parameter and ``**kwargs``, is called with a positional argument and a keyword argument where the keyword argument has the same name as the positional-only-parameter.
* Add new checker ``kwarg-superseded-by-positional-arg`` which emits a warning message for the above scenario.

Closes #8558

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

1 files changed, 39 insertions, 0 deletions

diff --git a/tests/functional/k/kwarg_superseded_by_positional_arg.py b/tests/functional/k/kwarg_superseded_by_positional_arg.py
new file mode 100644
index 000000000..050b2066c
--- /dev/null
+++ b/tests/functional/k/kwarg_superseded_by_positional_arg.py
@@ -0,0 +1,39 @@
+"""
+The `kwarg-superseded-by-positional-arg` warning message is emitted when a function is called with
+a keyword argument which shares a name with a positional-only parameter and
+the function contains a keyword variadic parameter dictionary.
+It may be surprising behaviour when the keyword argument is added to the
+keyword variadic parameter dictionary.
+"""
+
+
+def name1(apple, /, banana="Yellow banana", **kwargs):
+    """
+    Positional-only parameter, positional-or-keyword parameter and `**kwargs`.
+
+    >>> name1("Red apple", apple="Green apple", banana="Green banana")
+    Red apple
+    Green banana
+    {"apple": "Green apple"}
+    """
+
+    print(apple)
+    print(banana)
+    print(kwargs)
+
+
+# +1: [kwarg-superseded-by-positional-arg]
+name1("Red apple", apple="Green apple", banana="Green banana")
+name1("Red apple", banana="Green banana")
+
+
+def name2(apple="Green apple", /, **kwargs):
+    """
+    >>> name2(apple="Red apple")
+    Green apple
+    {'apple': 'Red apple'}
+    """
+    print(apple)
+    print(kwargs)
+
+name2(apple="Red apple")  # [kwarg-superseded-by-positional-arg]