From a3c5b31855f1bf3c4a4151d3fb7f412932825318 Mon Sep 17 00:00:00 2001
From: liugedragon <106804815+liugedragon@users.noreply.github.com>
Date: Mon, 9 Nov 2026 11:58:05 +0800
Subject: [PATCH] Fix compatibility checks for scientific float placeholders

---
 babel/messages/checkers.py      |  2 +-
 tests/messages/test_checkers.py | 35 +++++++++++++++++++++++++++++++++
 2 files changed, 36 insertions(+), 1 deletion(-)

diff --git a/babel/messages/checkers.py b/babel/messages/checkers.py
index cf0fbcd39..fb5f5193f 100644
--- a/babel/messages/checkers.py
+++ b/babel/messages/checkers.py
@@ -20,7 +20,7 @@
 _string_format_compatibilities = [
     {'i', 'd', 'u'},
     {'x', 'X'},
-    {'f', 'F', 'g', 'G'},
+    {'e', 'E', 'f', 'F', 'g', 'G'},
 ]
 
 
diff --git a/tests/messages/test_checkers.py b/tests/messages/test_checkers.py
index 01194e467..890e1cc1b 100644
--- a/tests/messages/test_checkers.py
+++ b/tests/messages/test_checkers.py
@@ -467,3 +467,38 @@ def test__validate_format_invalid(msgid, msgstr, error):
 )
 def test__validate_format_valid(msgid, msgstr):
     _validate_format(msgid, msgstr)
+
+
+@pytest.mark.parametrize('source_conversion', 'eEfFgG')
+@pytest.mark.parametrize('target_conversion', 'eEfFgG')
+@pytest.mark.parametrize('named', [False, True])
+def test_python_format_float_conversion_compatibility(
+    source_conversion, target_conversion, named,
+):
+    placeholder = '%(value)' if named else '%'
+    msgid = f'Value: {placeholder}{source_conversion}'
+    msgstr = f'Wert: {placeholder}{target_conversion}'
+    arguments = {'value': 1.234} if named else 1.234
+
+    assert isinstance(msgid % arguments, str)
+    assert isinstance(msgstr % arguments, str)
+    python_format(None, Message(msgid, msgstr))
+
+
+@pytest.mark.parametrize('source_conversion', 'eE')
+@pytest.mark.parametrize('target_conversion', 'sdx')
+@pytest.mark.parametrize('named', [False, True])
+def test_python_format_float_conversion_rejects_non_float(
+    source_conversion, target_conversion, named,
+):
+    placeholder = '%(value)' if named else '%'
+    with pytest.raises(TranslationError, match='incompatible format'):
+        _validate_format(
+            f'{placeholder}{source_conversion}', f'{placeholder}{target_conversion}',
+        )
+
+
+def test_python_format_float_conversion_plural():
+    catalog = Catalog(locale='en')
+    catalog.add(('%e item', '%e items'), ('%E article', '%g articles'))
+    assert list(catalog.check()) == []