fix: avoid false positive unbalanced-tuple-unpacking for cross-module function calls

Signed-off-by: Emmanuel Ferdman <[email protected]>

Author: emmanuel-ferdman

doc/whatsnew/fragments/10317.false_positive

@@ -0,0 +1,3 @@
+Fix false positive ``unbalanced-tuple-unpacking`` warning for cross-module function calls.
+
+Closes #10317

pylint/checkers/variables.py

@@ -3107,6 +3107,16 @@ def _check_unpacking(
             # Variable-length argument, we can't determine the length.
             return
 
+        # Skip check for function calls with empty inference from external modules.
+        # This avoids false positives when static analysis fails on library functions.
+        if (isinstance(node.value, nodes.Call) and
+            isinstance(inferred, (nodes.List, nodes.Tuple)) and
+            len(inferred.elts) == 0 and
+            hasattr(inferred, 'parent') and
+            isinstance(inferred.parent, nodes.Assign) and
+            node.root().name != inferred.root().name):
+            return
+
         # Attempt to check unpacking is properly balanced
         values = self._nodes_to_unpack(inferred)
         details = _get_unpacking_extra_info(node, inferred)

tests/functional/u/unbalanced/unbalanced_tuple_unpacking_function_calls.py

@@ -0,0 +1,27 @@
+"""Test for unbalanced tuple unpacking false positives with function calls."""
+
+import statistics
+
+
+def test_statistics_quantiles():
+    """Test that statistics.quantiles doesn't trigger false positive."""
+    q1, q2, q3 = statistics.quantiles(list(range(100)), n=4)
+    return q1, q2, q3
+
+
+def test_statistics_quantiles_different_n():
+    """Test statistics.quantiles with different n values."""
+    d1, d2, d3, d4, d5, d6, d7, d8, d9 = statistics.quantiles(list(range(100)), n=10)
+    return d1, d2, d3, d4, d5, d6, d7, d8, d9
+
+
+def empty_list_function():
+    """Function that returns an empty list."""
+    return []
+
+
+def test_legitimate_unbalanced_unpacking():
+    """Test that legitimate unbalanced unpacking still gets flagged."""
+    a, b, c = [1, 2]  # [unbalanced-tuple-unpacking]
+    x, y = empty_list_function()  # [unbalanced-tuple-unpacking]
+    return a, b, c, x, y

tests/functional/u/unbalanced/unbalanced_tuple_unpacking_function_calls.txt

@@ -0,0 +1,2 @@
+unbalanced-tuple-unpacking:25:4:25:20:test_legitimate_unbalanced_unpacking:"Possible unbalanced tuple unpacking with sequence '[1, 2]': left side has 3 labels, right side has 2 values":INFERENCE
+unbalanced-tuple-unpacking:26:4:26:32:test_legitimate_unbalanced_unpacking:"Possible unbalanced tuple unpacking with sequence defined at line 20: left side has 2 labels, right side has 0 values":INFERENCE