From 6fab8e37f97da62555b94a7f1f0c6b0e50cda7bd Mon Sep 17 00:00:00 2001
From: Kumar Aditya <59607654+kumaraditya303@users.noreply.github.com>
Date: Sat, 25 Jun 2022 16:15:43 +0000
Subject: [PATCH 1/5] make _struct module types immutable

---
 Modules/_struct.c | 6 ++++--
 1 file changed, 4 insertions(+), 2 deletions(-)

diff --git a/Modules/_struct.c b/Modules/_struct.c
index 20307ad15be814..9d66568a282662 100644
--- a/Modules/_struct.c
+++ b/Modules/_struct.c
@@ -1741,7 +1741,8 @@ static PyType_Spec unpackiter_type_spec = {
     "_struct.unpack_iterator",
     sizeof(unpackiterobject),
     0,
-    Py_TPFLAGS_DEFAULT | Py_TPFLAGS_HAVE_GC,
+    (Py_TPFLAGS_DEFAULT | Py_TPFLAGS_HAVE_GC |
+     Py_TPFLAGS_IMMUTABLETYPE),
     unpackiter_type_slots
 };
 
@@ -2110,7 +2111,8 @@ static PyType_Spec PyStructType_spec = {
     "_struct.Struct",
     sizeof(PyStructObject),
     0,
-    Py_TPFLAGS_DEFAULT | Py_TPFLAGS_HAVE_GC | Py_TPFLAGS_BASETYPE,
+    (Py_TPFLAGS_DEFAULT | Py_TPFLAGS_HAVE_GC |
+     Py_TPFLAGS_BASETYPE | Py_TPFLAGS_IMMUTABLETYPE),
     PyStructType_slots
 };
 

From cbc4cb101412cbaf802df2732d7de3dfb31b8a82 Mon Sep 17 00:00:00 2001
From: Kumar Aditya <59607654+kumaraditya303@users.noreply.github.com>
Date: Sat, 25 Jun 2022 16:25:37 +0000
Subject: [PATCH 2/5] add test

---
 Lib/test/test_struct.py | 10 ++++++++++
 1 file changed, 10 insertions(+)

diff --git a/Lib/test/test_struct.py b/Lib/test/test_struct.py
index 8f14ed30588810..e0bdc23d4f52fa 100644
--- a/Lib/test/test_struct.py
+++ b/Lib/test/test_struct.py
@@ -689,6 +689,16 @@ def test__struct_reference_cycle_cleaned_up(self):
         self.assertIsNone(
             module_ref(), "_struct module was not garbage collected")
 
+    def test__struct_types_immutable(self) -> None:
+        # See https://github.com/python/cpython/issues/94254
+
+        Struct = struct.Struct
+        unpack_iterator = type(struct.iter_unpack("b", b'x'))
+        for cls in (Struct, unpack_iterator):
+            with self.assertRaises(TypeError):
+                cls.x = 1
+
+
     def test_issue35714(self):
         # Embedded null characters should not be allowed in format strings.
         for s in '\0', '2\0i', b'\0':

From 1b1ac971dc4eea3bb93cd13a58edb0b1000a7a6c Mon Sep 17 00:00:00 2001
From: "blurb-it[bot]" <43283697+blurb-it[bot]@users.noreply.github.com>
Date: Sat, 25 Jun 2022 16:27:04 +0000
Subject: [PATCH 3/5] =?UTF-8?q?=F0=9F=93=9C=F0=9F=A4=96=20Added=20by=20blu?=
 =?UTF-8?q?rb=5Fit.?=
MIME-Version: 1.0
Content-Type: text/plain; charset=UTF-8
Content-Transfer-Encoding: 8bit

---
 .../next/Library/2022-06-25-16-27-02.gh-issue-94254.beP16v.rst   | 1 +
 1 file changed, 1 insertion(+)
 create mode 100644 Misc/NEWS.d/next/Library/2022-06-25-16-27-02.gh-issue-94254.beP16v.rst

diff --git a/Misc/NEWS.d/next/Library/2022-06-25-16-27-02.gh-issue-94254.beP16v.rst b/Misc/NEWS.d/next/Library/2022-06-25-16-27-02.gh-issue-94254.beP16v.rst
new file mode 100644
index 00000000000000..81482bcd4f8974
--- /dev/null
+++ b/Misc/NEWS.d/next/Library/2022-06-25-16-27-02.gh-issue-94254.beP16v.rst
@@ -0,0 +1 @@
+Fixed types of :mod:`struct` module to be immutable. Patch by Kumar Aditya.

From 2f25d3f26fb3310ef671b0b5fe2093fb654d0a96 Mon Sep 17 00:00:00 2001
From: Kumar Aditya <59607654+kumaraditya303@users.noreply.github.com>
Date: Sat, 25 Jun 2022 16:30:34 +0000
Subject: [PATCH 4/5] use subtest

---
 Lib/test/test_struct.py | 5 +++--
 1 file changed, 3 insertions(+), 2 deletions(-)

diff --git a/Lib/test/test_struct.py b/Lib/test/test_struct.py
index e0bdc23d4f52fa..b65c188897fd67 100644
--- a/Lib/test/test_struct.py
+++ b/Lib/test/test_struct.py
@@ -695,8 +695,9 @@ def test__struct_types_immutable(self) -> None:
         Struct = struct.Struct
         unpack_iterator = type(struct.iter_unpack("b", b'x'))
         for cls in (Struct, unpack_iterator):
-            with self.assertRaises(TypeError):
-                cls.x = 1
+            with self.subTest(cls=cls):
+                with self.assertRaises(TypeError):
+                    cls.x = 1
 
 
     def test_issue35714(self):

From 2ad2cec6cb3985454c0c206dfb2b59020a9fd7ca Mon Sep 17 00:00:00 2001
From: Kumar Aditya <59607654+kumaraditya303@users.noreply.github.com>
Date: Sun, 26 Jun 2022 09:08:27 +0000
Subject: [PATCH 5/5] mark cpython specific

---
 Lib/test/test_struct.py | 3 ++-
 1 file changed, 2 insertions(+), 1 deletion(-)

diff --git a/Lib/test/test_struct.py b/Lib/test/test_struct.py
index b65c188897fd67..ab738770546c0b 100644
--- a/Lib/test/test_struct.py
+++ b/Lib/test/test_struct.py
@@ -689,7 +689,8 @@ def test__struct_reference_cycle_cleaned_up(self):
         self.assertIsNone(
             module_ref(), "_struct module was not garbage collected")
 
-    def test__struct_types_immutable(self) -> None:
+    @support.cpython_only
+    def test__struct_types_immutable(self):
         # See https://github.com/python/cpython/issues/94254
 
         Struct = struct.Struct