From: tonghuaroot (童话) <tonghuaroot@gmail.com>
Date: Fri, 31 Jul 2026 10:58:59 +0000 (+0800)
Subject: gh-154738: Propagate reparse-deferral setting to pyexpat subparsers (GH-154739)
X-Git-Url: http://git.ipfire.org/gitweb/?a=commitdiff_plain;h=7d760134cc20f444412c54fc8395ca6f2421ad73;p=thirdparty%2FPython%2Fcpython.git

gh-154738: Propagate reparse-deferral setting to pyexpat subparsers (GH-154739)
---

diff --git a/Lib/test/test_pyexpat.py b/Lib/test/test_pyexpat.py
index a2ef67baadd4..54dfa95ce8bf 100644
--- a/Lib/test/test_pyexpat.py
+++ b/Lib/test/test_pyexpat.py
@@ -1045,6 +1045,13 @@ class ParentParserLifetimeTest(unittest.TestCase):
         del parser
         del subparser
 
+    def test_subparser_inherits_reparse_deferral(self):
+        for enabled in (True, False):
+            parser = expat.ParserCreate()
+            parser.SetReparseDeferralEnabled(enabled)
+            subparser = parser.ExternalEntityParserCreate(None)
+            self.assertEqual(subparser.GetReparseDeferralEnabled(), enabled)
+
 
 class ExternalEntityParserCreateErrorTest(unittest.TestCase):
     """ExternalEntityParserCreate error paths should not crash or leak
diff --git a/Misc/NEWS.d/next/Library/2026-07-26-00-00-00.gh-issue-154738.Rd5Pxe.rst b/Misc/NEWS.d/next/Library/2026-07-26-00-00-00.gh-issue-154738.Rd5Pxe.rst
new file mode 100644
index 000000000000..1a6e1a301db4
--- /dev/null
+++ b/Misc/NEWS.d/next/Library/2026-07-26-00-00-00.gh-issue-154738.Rd5Pxe.rst
@@ -0,0 +1,3 @@
+Fix :meth:`!ExternalEntityParserCreate` not propagating the reparse-deferral
+setting to the subparser, which left :meth:`!GetReparseDeferralEnabled`
+returning an uninitialized value.  Patch by tonghuaroot.
diff --git a/Modules/pyexpat.c b/Modules/pyexpat.c
index f9e7e057f7e0..397a441f574f 100644
--- a/Modules/pyexpat.c
+++ b/Modules/pyexpat.c
@@ -1118,6 +1118,7 @@ pyexpat_xmlparser_ExternalEntityParserCreate_impl(xmlparseobject *self,
     new_parser->specified_attributes = self->specified_attributes;
     new_parser->in_callback = 0;
     new_parser->ns_prefixes = self->ns_prefixes;
+    new_parser->reparse_deferral_enabled = self->reparse_deferral_enabled;
     new_parser->itself = XML_ExternalEntityParserCreate(self->itself, context,
                                                         encoding);
     // The new subparser will make use of the parent XML_Parser inside of Expat.