Fix issue #5969 for `modified_iterating-list` (#5986)

When the list/dict/set being iterated through is a function call.

Co-authored-by: Pierre Sassoulas <pierre.sassoulas@gmail.com>

3 files changed, 24 insertions, 2 deletions

diff --git a/ChangeLog b/ChangeLog
index ea6f7701e..be25eceb2 100644
--- a/ChangeLog
+++ b/ChangeLog
@@ -39,6 +39,11 @@ Release date: TBA
 
   Closes #5187
 
+* Fix program crash for ``modified_iterating-list/set/dict`` when the list/dict/set
+  being iterated through is a function call.
+
+  Closes #5969
+
 * Don't emit ``broken-noreturn`` and ``broken-collections-callable`` errors
   inside ``if TYPE_CHECKING`` blocks.
 
diff --git a/pylint/checkers/modified_iterating_checker.py b/pylint/checkers/modified_iterating_checker.py
index d1fe08d40..ca2a0c900 100644
--- a/pylint/checkers/modified_iterating_checker.py
+++ b/pylint/checkers/modified_iterating_checker.py
@@ -57,8 +57,9 @@ class ModifiedIterationChecker(checkers.BaseChecker):
     )
     def visit_for(self, node: nodes.For) -> None:
         iter_obj = node.iter
-        for body_node in node.body:
-            self._modified_iterating_check_on_node_and_children(body_node, iter_obj)
+        if isinstance(iter_obj, nodes.Name):
+            for body_node in node.body:
+                self._modified_iterating_check_on_node_and_children(body_node, iter_obj)
 
     def _modified_iterating_check_on_node_and_children(
         self, body_node: nodes.NodeNG, iter_obj: nodes.NodeNG
diff --git a/tests/functional/m/modified_iterating.py b/tests/functional/m/modified_iterating.py
index 32155fbc8..8817c1db0 100644
--- a/tests/functional/m/modified_iterating.py
+++ b/tests/functional/m/modified_iterating.py
@@ -55,3 +55,19 @@ for l in item_list:
             item_list.remove(1)  # [modified-iterating-list]
             for _ in []:
                 item_list.append(1)  # [modified-iterating-list]
+
+
+def format_manifest_serializer_errors(errors):
+    """Regression test for issue #5969 - iter_obj is a function call."""
+    errors_messages = []
+    for key, value in errors.items():
+        for message in format_manifest_serializer_errors(value):
+            error_message = f"{key}: {message}"
+            errors_messages.append(error_message)
+    return errors_messages
+
+
+dict1 = {"1": 1}
+dict2 = {"2": 2}
+for item in dict1:
+    dict2[item] = 1