From 40a675543fb98eb6b9987bdd438b40c04c68ff68 Mon Sep 17 00:00:00 2001
From: Matt Davis <6775756+nitzmahone@users.noreply.github.com>
Date: Thu, 29 May 2025 09:50:01 -0700
Subject: [PATCH] fix from_yaml_all filter inconsistent None handling (#85223)

* fix from_yaml_all filter inconsistent None handling

* always returns empty list for None or empty string input

* deprecate non-string inputs for from_yaml and from_yaml_all

(cherry picked from commit 356bf336bdd7741bd9044abe33d7e71ea13d276f)
---
 changelogs/fragments/from_yaml_all.yml              |  2 ++
 lib/ansible/plugins/filter/core.py                  | 10 ++++++++++
 test/integration/targets/filter_core/tasks/main.yml |  2 ++
 3 files changed, 14 insertions(+)
 create mode 100644 changelogs/fragments/from_yaml_all.yml

diff --git a/changelogs/fragments/from_yaml_all.yml b/changelogs/fragments/from_yaml_all.yml
new file mode 100644
index 00000000000..2e65c15961b
--- /dev/null
+++ b/changelogs/fragments/from_yaml_all.yml
@@ -0,0 +1,2 @@
+bugfixes:
+  - from_yaml_all filter - `None` and empty string inputs now always return an empty list. Previously, `None` was returned in Jinja native mode and empty list in classic mode.
diff --git a/lib/ansible/plugins/filter/core.py b/lib/ansible/plugins/filter/core.py
index e28fadadfab..6afd3045fd7 100644
--- a/lib/ansible/plugins/filter/core.py
+++ b/lib/ansible/plugins/filter/core.py
@@ -247,20 +247,30 @@ def regex_escape(string, re_type='python'):
 
 
 def from_yaml(data):
+    if data is None:
+        return None
+
     if isinstance(data, string_types):
         # The ``text_type`` call here strips any custom
         # string wrapper class, so that CSafeLoader can
         # read the data
         return yaml_load(text_type(to_text(data, errors='surrogate_or_strict')))
+
+    display.deprecated(f"The from_yaml filter ignored non-string input of type {native_type_name(data)!r}.", version='2.23', obj=data)
     return data
 
 
 def from_yaml_all(data):
+    if data is None:
+        return []  # backward compatibility; ensure consistent result between classic/native Jinja for None/empty string input
+
     if isinstance(data, string_types):
         # The ``text_type`` call here strips any custom
         # string wrapper class, so that CSafeLoader can
         # read the data
         return yaml_load_all(text_type(to_text(data, errors='surrogate_or_strict')))
+
+    display.deprecated(f"The from_yaml_all filter ignored non-string input of type {native_type_name(data)!r}.", version='2.23', obj=data)
     return data
 
 
diff --git a/test/integration/targets/filter_core/tasks/main.yml b/test/integration/targets/filter_core/tasks/main.yml
index 7e82ab4b4e9..7d7590ecea7 100644
--- a/test/integration/targets/filter_core/tasks/main.yml
+++ b/test/integration/targets/filter_core/tasks/main.yml
@@ -471,6 +471,8 @@
       - "2|from_yaml_all == 2"
       - "unsafe_fruit|from_yaml == {'bananas': 'yellow', 'apples': 'red'}"
       - "unsafe_fruit_all|from_yaml_all|list == [{'bananas': 'yellow'}, {'apples': 'red'}]"
+      - None | from_yaml is none
+      - None | from_yaml_all == []
   vars:
     unsafe_fruit: !unsafe |
       ---