typecheck: simplify variadic positional detection (#5417)

The isinstance checks were not necessary here and caused several false
positives where a function with variadic positional argument was called,
like for example when the call is used as a function argument, in a if,
while or with statement.

Co-authored-by: Pierre Sassoulas <[email protected]>

Author: perrinjerome

CONTRIBUTORS.txt

@@ -581,6 +581,8 @@ contributors:
 
 * Harshil (harshil21): contributor
 
+* Jérome Perrin (perrinjerome): contributor
+
 * Felix von Drigalski (felixvd): contributor
 
 * Philipp Albrecht (pylbrecht): contributor

ChangeLog

@@ -32,6 +32,11 @@ Release date: TBA
 * Some files in ``pylint.testutils`` were deprecated. In the future imports should be done from the
   ``pylint.testutils.functional`` namespace directly.
 
+* Fixed false positives for ``no-value-for-parameter`` with variadic
+  positional arguments.
+
+  Closes #5416
+
 * ``safe_infer`` no longer makes an inference when given two function
   definitions with differing numbers of arguments.
 

pylint/checkers/typecheck.py

@@ -630,17 +630,7 @@ def _no_context_variadic_keywords(node, scope):
 
 
 def _no_context_variadic_positional(node, scope):
-    variadics = ()
-    if isinstance(scope, nodes.Lambda) and not isinstance(scope, nodes.FunctionDef):
-        variadics = node.starargs + node.kwargs
-    else:
-        statement = node.statement()
-        if isinstance(
-            statement, (nodes.Expr, nodes.Return, nodes.Assign)
-        ) and isinstance(statement.value, nodes.Call):
-            call = statement.value
-            variadics = call.starargs + call.kwargs
-
+    variadics = node.starargs + node.kwargs
     return _no_context_variadic(node, scope.args.vararg, nodes.Starred, variadics)
 
 

tests/functional/r/regression/regression_no_value_for_parameter.py

@@ -28,9 +28,20 @@ def varargs_good(*parts):
 
 
 def varargs_no_expr(*parts):
-    """False positive below this line"""
+    """False positives below this line"""
     ret = os.path.join(*parts)
-    return ret
+    if ret:
+        return ret
+    print(os.path.join(*parts))
+    if os.path.join(*parts):
+        print()
+    elif os.path.join(*parts):
+        print()
+    while os.path.join(*parts):
+        print()
+    with os.path.join(*parts): # pylint:disable=not-context-manager
+        print()
+    return os.path.join(*parts) + os.path.join(*parts) - os.path.join(*parts)
 
 
 def kwargs_good(**kwargs):
@@ -39,4 +50,15 @@ def kwargs_good(**kwargs):
 
 def kwargs_no_expr(**kwargs):
     ret = func(**kwargs)
-    return ret
+    if ret:
+        return ret
+    print(func(**kwargs))
+    if func(**kwargs):
+        print()
+    elif func(**kwargs):
+        print()
+    while func(**kwargs):
+        print()
+    with func(**kwargs): # pylint:disable=not-context-manager
+        print()
+    return func(**kwargs) + func(**kwargs) - func(**kwargs)