From b77759e01e81d961467e7f50ef5cb0ea72371721 Mon Sep 17 00:00:00 2001
From: marat <khagazheev@artlebedev.ru>
Date: Thu, 19 Feb 2026 22:44:52 +0300
Subject: [PATCH 1/2] Unify behavior of unsupported %-format specifiers

---
 Lib/_pydatetime.py         | 10 ++++++++++
 Lib/test/datetimetester.py |  6 ++++++
 Modules/_datetimemodule.c  | 14 ++++++++++++++
 3 files changed, 30 insertions(+)

diff --git a/Lib/_pydatetime.py b/Lib/_pydatetime.py
index b6d68f2372850a..97f359d7866aa2 100644
--- a/Lib/_pydatetime.py
+++ b/Lib/_pydatetime.py
@@ -284,6 +284,16 @@ def _wrap_strftime(object, format, timetuple):
                         push('{:04}'.format(year))
                         if ch == 'F':
                             push('-{:02}-{:02}'.format(*timetuple[1:3]))
+                elif ch == '-':
+                    if i < n:
+                        next_ch = format[i]
+                        i += 1
+                        if next_ch not in 'dmHIMSjUWVy':
+                            push('%%-' + next_ch)
+                        else:
+                           push('%-' + next_ch)
+                    else:
+                        push('%-')
                 else:
                     push('%')
                     push(ch)
diff --git a/Lib/test/datetimetester.py b/Lib/test/datetimetester.py
index 97eec618932aa5..2e9cbbc01ee7b1 100644
--- a/Lib/test/datetimetester.py
+++ b/Lib/test/datetimetester.py
@@ -15,6 +15,7 @@
 import textwrap
 import unittest
 import warnings
+import platform
 
 from array import array
 
@@ -1589,6 +1590,11 @@ def test_strftime(self):
         self.assertEqual(t.strftime(""), "") # SF bug #761337
         self.assertEqual(t.strftime('x'*1000), 'x'*1000) # SF bug #1556784
 
+        # unsupported %-format specifiers are passed through unchanged.
+        self.assertEqual(t.strftime("%-1"), "%-1")
+        self.assertEqual(t.strftime("%--"), "%--")
+        self.assertEqual(t.strftime("%-#"), "%-#")
+
         self.assertRaises(TypeError, t.strftime) # needs an arg
         self.assertRaises(TypeError, t.strftime, "one", "two") # too many args
         self.assertRaises(TypeError, t.strftime, 42) # arg wrong type
diff --git a/Modules/_datetimemodule.c b/Modules/_datetimemodule.c
index 8f64e572bd6086..f5ad660202d68a 100644
--- a/Modules/_datetimemodule.c
+++ b/Modules/_datetimemodule.c
@@ -2003,6 +2003,20 @@ wrap_strftime(PyObject *object, PyObject *format, PyObject *timetuple,
             }
             continue;
         }
+        else if (ch == '-' && i < flen) {
+            Py_UCS4 next_ch = PyUnicode_READ_CHAR(format, i);
+            i++;
+
+             if (strchr("dmHIMSjUWVy", (int)next_ch) == NULL) {
+                replacement = PyUnicode_FromFormat("%%%%-%c", (char)next_ch);
+                if (replacement == NULL) {
+                    goto Error;
+                }
+            }
+            else {
+                continue;
+            }
+        }
         else {
             /* percent followed by something else */
             continue;

From 4b09c8e3f8c19f25d028900657110eb6d4b5048c Mon Sep 17 00:00:00 2001
From: marat <khagazheev@artlebedev.ru>
Date: Thu, 19 Feb 2026 23:01:18 +0300
Subject: [PATCH 2/2] Remove platform from tests

---
 Lib/test/datetimetester.py | 1 -
 1 file changed, 1 deletion(-)

diff --git a/Lib/test/datetimetester.py b/Lib/test/datetimetester.py
index 2e9cbbc01ee7b1..1edec59d71764c 100644
--- a/Lib/test/datetimetester.py
+++ b/Lib/test/datetimetester.py
@@ -15,7 +15,6 @@
 import textwrap
 import unittest
 import warnings
-import platform
 
 from array import array