From dc3e515d9f3905901b31cccb1a462dbe35d5b824 Mon Sep 17 00:00:00 2001
From: Jacob Walls <jacobtylerwalls@gmail.com>
Date: Sat, 27 Nov 2021 09:51:19 -0500
Subject: [PATCH] Fix #3675: `safe_infer` now finds ambiguity when number of
 arguments differ

---
 ChangeLog                                     |  5 +++++
 pylint/checkers/utils.py                      | 13 +++++++++++++
 .../t/too/too_many_function_args.py           | 19 +++++++++++++++++++
 3 files changed, 37 insertions(+)
 create mode 100644 tests/functional/t/too/too_many_function_args.py

diff --git a/ChangeLog b/ChangeLog
index f77b7e8706..b3dab8b8b9 100644
--- a/ChangeLog
+++ b/ChangeLog
@@ -14,6 +14,11 @@ Release date: TBA
 * Some files in ``pylint.testutils`` were deprecated. In the future imports should be done from the
   ``pylint.testutils.functional`` namespace directly.
 
+* ``safe_infer`` no longer makes an inference given two function
+  definitions with differing numbers of arguments.
+
+  Closes #3675
+
 * Fix ``unnecessary_dict_index_lookup`` false positive when deleting a dictionary's entry.
 
   Closes #4716
diff --git a/pylint/checkers/utils.py b/pylint/checkers/utils.py
index 5a03ca4f42..5fa3089b88 100644
--- a/pylint/checkers/utils.py
+++ b/pylint/checkers/utils.py
@@ -1260,6 +1260,19 @@ def safe_infer(node: nodes.NodeNG, context=None) -> Optional[nodes.NodeNG]:
             inferred_type = _get_python_type_of_node(inferred)
             if inferred_type not in inferred_types:
                 return None  # If there is ambiguity on the inferred node.
+            if isinstance(inferred, astroid.FunctionDef):
+                # Special case due to unexpected inference ambiguity
+                if (
+                    inferred.name == "TemporaryFile"
+                    and value.name == "NamedTemporaryFile"
+                ):
+                    continue
+                if (
+                    inferred.args.args is not None
+                    and value.args.args is not None
+                    and len(inferred.args.args) != len(value.args.args)
+                ):
+                    return None  # Different number of arguments indicates ambiguity
     except astroid.InferenceError:
         return None  # There is some kind of ambiguity
     except StopIteration:
diff --git a/tests/functional/t/too/too_many_function_args.py b/tests/functional/t/too/too_many_function_args.py
new file mode 100644
index 0000000000..c5ca4f78eb
--- /dev/null
+++ b/tests/functional/t/too/too_many_function_args.py
@@ -0,0 +1,19 @@
+"""https://github.com/PyCQA/pylint/issues/3675"""
+
+
+def noop(x):  # pylint: disable=invalid-name
+    """Return value unchanged"""
+    return x
+
+
+def add(x, y):  # pylint: disable=invalid-name
+    """Add two values"""
+    return x + y
+
+
+def main(param):
+    """Should not emit too-many-function-args"""
+    tmp = noop  # matched first
+    if param == 0:
+        tmp = add
+    return tmp(1, 1.01)