Handle more `unnecessary-lambda` cases when dealing with additional kwargs in wrapped calls

Close #2845

3 files changed, 18 insertions, 2 deletions

diff --git a/ChangeLog b/ChangeLog
index c41108a83..0634fe387 100644
--- a/ChangeLog
+++ b/ChangeLog
@@ -7,6 +7,10 @@ What's New in Pylint 2.4.0?
 
 Release date: TBA
 
+* Handle more `unnecessary-lambda` cases when dealing with additional kwargs in wrapped calls
+
+  Close #2845
+
 * Better postponed evaluation of annotations handling
 
   Close #2847
diff --git a/pylint/checkers/base.py b/pylint/checkers/base.py
index 16dd824c2..64ca43f6f 100644
--- a/pylint/checkers/base.py
+++ b/pylint/checkers/base.py
@@ -47,6 +47,7 @@ from typing import Pattern
 import astroid
 import astroid.bases
 import astroid.scoped_nodes
+from astroid.arguments import CallSite
 
 import pylint.utils as lint_utils
 from pylint import checkers, exceptions, interfaces
@@ -1174,13 +1175,12 @@ class BasicChecker(_BasicChecker):
             # return something else (but we don't check that, yet).
             return
 
+        call_site = CallSite.from_call(call)
         ordinary_args = list(node.args.args)
         new_call_args = list(self._filter_vararg(node, call.args))
         if node.args.kwarg:
             if self._has_variadic_argument(call.kwargs, node.args.kwarg):
                 return
-        elif call.kwargs or call.keywords:
-            return
 
         if node.args.vararg:
             if self._has_variadic_argument(call.starargs, node.args.vararg):
@@ -1188,6 +1188,16 @@ class BasicChecker(_BasicChecker):
         elif call.starargs:
             return
 
+        if call.keywords:
+            # Look for additional keyword arguments that are not part
+            # of the lambda's signature
+            lambda_kwargs = {keyword.name for keyword in node.args.defaults}
+            if len(lambda_kwargs) != len(call_site.keyword_arguments):
+                # Different lengths, so probably not identical
+                return
+            if set(call_site.keyword_arguments).difference(lambda_kwargs):
+                return
+
         # The "ordinary" arguments must be in a correspondence such that:
         # ordinary_args[i].name == call.args[i].name.
         if len(ordinary_args) != len(new_call_args):
diff --git a/pylint/test/functional/unnecessary_lambda.py b/pylint/test/functional/unnecessary_lambda.py
index 461710919..f0bd775f3 100644
--- a/pylint/test/functional/unnecessary_lambda.py
+++ b/pylint/test/functional/unnecessary_lambda.py
@@ -49,3 +49,5 @@ _ = lambda: _ANYARGS(func=42)
 

 # Don't warn about this.

 _ = lambda: code().analysis()

+

+_ = lambda **kwargs: dict(bar=42, **kwargs)