Suggest keyword attributes

Author: cdce8p

doc/user_guide/checkers/features.rst

@@ -697,7 +697,7 @@ Match Statements checker Messages
 :match-class-bind-self (R1905): *Use '%s() as %s' instead*
   Match class patterns are faster if the name binding happens for the whole
   pattern and any lookup for `__match_args__` can be avoided.
-:match-class-positional-attributes (R1906): *Use keyword attributes instead of positional ones*
+:match-class-positional-attributes (R1906): *Use keyword attributes instead of positional ones (%s)*
   Keyword attributes are more explicit and slightly faster since CPython can
   skip the `__match_args__` lookup.
 

pylint/checkers/match_statements_checker.py

@@ -71,7 +71,7 @@ class MatchStatementChecker(BaseChecker):
             "can be avoided.",
         ),
         "R1906": (
-            "Use keyword attributes instead of positional ones",
+            "Use keyword attributes instead of positional ones (%s)",
             "match-class-positional-attributes",
             "Keyword attributes are more explicit and slightly faster "
             "since CPython can skip the `__match_args__` lookup.",
@@ -184,22 +184,6 @@ def visit_matchclass(self, node: nodes.MatchClass) -> None:
         attrs: set[str] = set()
         dups: set[str] = set()
 
-        if node.patterns:
-            if isinstance(node, nodes.MatchClass) and isinstance(node.cls, nodes.Name):
-                inferred = safe_infer(node.cls)
-                if not (
-                    isinstance(inferred, nodes.ClassDef)
-                    and (
-                        inferred.qname() in MATCH_CLASS_SELF_NAMES
-                        or "tuple" in inferred.basenames
-                    )
-                ):
-                    self.add_message(
-                        "match-class-positional-attributes",
-                        node=node,
-                        confidence=INFERENCE,
-                    )
-
         if (
             node.patterns
             and (match_args := self.get_match_args_for_class(node.cls)) is not None
@@ -213,6 +197,22 @@ def visit_matchclass(self, node: nodes.MatchClass) -> None:
                 )
                 return
 
+            inferred = safe_infer(node.cls)
+            if not (
+                isinstance(inferred, nodes.ClassDef)
+                and (
+                    inferred.qname() in MATCH_CLASS_SELF_NAMES
+                    or "tuple" in inferred.basenames
+                )
+            ):
+                attributes = [f"'{attr}'" for attr in match_args[: len(node.patterns)]]
+                self.add_message(
+                    "match-class-positional-attributes",
+                    node=node,
+                    args=(", ".join(attributes),),
+                    confidence=INFERENCE,
+                )
+
             for i in range(len(node.patterns)):
                 name = match_args[i]
                 self.check_duplicate_sub_patterns(name, node, attrs=attrs, dups=dups)

tests/functional/m/match_class_pattern.txt

@@ -9,5 +9,5 @@ multiple-class-sub-patterns:49:13:49:29:f2:Multiple sub-patterns for attribute x
 undefined-variable:55:13:55:23:f2:Undefined variable 'NotDefined':UNDEFINED
 match-class-bind-self:60:17:60:18:f3:Use 'int() as y' instead:HIGH
 match-class-bind-self:63:17:63:18:f3:Use 'str() as y' instead:HIGH
-match-class-positional-attributes:75:13:75:17:f4:Use keyword attributes instead of positional ones:INFERENCE
-match-class-positional-attributes:77:13:77:20:f4:Use keyword attributes instead of positional ones:INFERENCE
+match-class-positional-attributes:75:13:75:17:f4:Use keyword attributes instead of positional ones ('x'):INFERENCE
+match-class-positional-attributes:77:13:77:20:f4:Use keyword attributes instead of positional ones ('x', 'y'):INFERENCE