From d392ea5d8a11049a275207cf18e488bf19a57c69 Mon Sep 17 00:00:00 2001
From: Mark Byrne <31762852+mbyrnepr2@users.noreply.github.com>
Date: Tue, 16 May 2023 10:34:47 +0200
Subject: Add new checker `kwarg-superseded-by-positional-arg` and fix a false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* Add new checker ``kwarg-superseded-by-positional-arg`` which emits a warning message for the above scenario.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>
---
 pylint/checkers/typecheck.py | 24 +++++++++++++++++++-----
 1 file changed, 19 insertions(+), 5 deletions(-)

(limited to 'pylint')

diff --git a/pylint/checkers/typecheck.py b/pylint/checkers/typecheck.py
index 97a7460a8..767f4ef32 100644
--- a/pylint/checkers/typecheck.py
+++ b/pylint/checkers/typecheck.py
@@ -399,6 +399,13 @@ MSGS: dict[str, MessageDefinitionTuple] = {
         "isinstance-second-argument-not-valid-type",
         "Emitted when the second argument of an isinstance call is not a type.",
     ),
+    "W1117": (
+        "%r will be included in %r since a positional-only parameter with this name already exists",
+        "kwarg-superseded-by-positional-arg",
+        "Emitted when a function is called with a keyword argument that has the "
+        "same name as a positional-only parameter and the function contains a "
+        "keyword variadic parameter dict.",
+    ),
 }
 
 # builtin sequence types in Python 2 and 3.
@@ -1548,6 +1555,18 @@ accessed. Python regular expressions are accepted.",
 
         # 2. Match the keyword arguments.
         for keyword in keyword_args:
+            # Skip if `keyword` is the same name as a positional-only parameter
+            # and a `**kwargs` parameter exists.
+            if called.args.kwarg and keyword in [
+                arg.name for arg in called.args.posonlyargs
+            ]:
+                self.add_message(
+                    "kwarg-superseded-by-positional-arg",
+                    node=node,
+                    args=(keyword, f"**{called.args.kwarg}"),
+                    confidence=HIGH,
+                )
+                continue
             if keyword in parameter_name_to_index:
                 i = parameter_name_to_index[keyword]
                 if parameters[i][1]:
@@ -1564,11 +1583,6 @@ accessed. Python regular expressions are accepted.",
                             node=node,
                             args=(keyword, callable_name),
                         )
-                elif (
-                    keyword in [arg.name for arg in called.args.posonlyargs]
-                    and called.args.kwarg
-                ):
-                    pass
                 else:
                     parameters[i] = (parameters[i][0], True)
             elif keyword in kwparams:
-- 
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