From 10db28bfcf2b949e13312d0d2f1b3dd3c9585e69 Mon Sep 17 00:00:00 2001
From: "Miss Islington (bot)"
 <31488909+miss-islington@users.noreply.github.com>
Date: Mon, 1 May 2023 13:18:29 -0700
Subject: [PATCH] [3.11] gh-104018: disallow "z" format specifier in %-format
 of byte strings (GH-104033) (#104058)

gh-104018: disallow "z" format specifier in %-format of byte strings (GH-104033)

PEP-0682 specified that %-formatting would not support the "z" specifier,
but it was unintentionally allowed for bytes. This PR makes use of the "z"
flag an error for %-formatting in a bytestring.

Issue: GH-104018

---------

(cherry picked from commit 3ed8c882902a6982fd67e898a5b8a2d619fb5ddf)

Co-authored-by: John Belmonte <john@neggie.net>
Co-authored-by: blurb-it[bot] <43283697+blurb-it[bot]@users.noreply.github.com>
---
 Lib/test/test_format.py                                         | 2 ++
 .../2023-05-01-12-03-52.gh-issue-104018.PFxGS4.rst              | 1 +
 Objects/bytesobject.c                                           | 1 -
 3 files changed, 3 insertions(+), 1 deletion(-)
 create mode 100644 Misc/NEWS.d/next/Core and Builtins/2023-05-01-12-03-52.gh-issue-104018.PFxGS4.rst

diff --git a/Lib/test/test_format.py b/Lib/test/test_format.py
index 69b0d5f1c5a515..6fa49dbc0b730c 100644
--- a/Lib/test/test_format.py
+++ b/Lib/test/test_format.py
@@ -619,6 +619,8 @@ def test_specifier_z_error(self):
         error_msg = re.escape("unsupported format character 'z'")
         with self.assertRaisesRegex(ValueError, error_msg):
             "%z.1f" % 0  # not allowed in old style string interpolation
+        with self.assertRaisesRegex(ValueError, error_msg):
+            b"%z.1f" % 0
 
 
 if __name__ == "__main__":
diff --git a/Misc/NEWS.d/next/Core and Builtins/2023-05-01-12-03-52.gh-issue-104018.PFxGS4.rst b/Misc/NEWS.d/next/Core and Builtins/2023-05-01-12-03-52.gh-issue-104018.PFxGS4.rst
new file mode 100644
index 00000000000000..f3cadaee0e32d9
--- /dev/null
+++ b/Misc/NEWS.d/next/Core and Builtins/2023-05-01-12-03-52.gh-issue-104018.PFxGS4.rst	
@@ -0,0 +1 @@
+Disallow the "z" format specifier in %-format of bytes objects.
diff --git a/Objects/bytesobject.c b/Objects/bytesobject.c
index 8dd1a2d52467af..61cde0ef34bf99 100644
--- a/Objects/bytesobject.c
+++ b/Objects/bytesobject.c
@@ -714,7 +714,6 @@ _PyBytes_FormatEx(const char *format, Py_ssize_t format_len,
                 case ' ': flags |= F_BLANK; continue;
                 case '#': flags |= F_ALT; continue;
                 case '0': flags |= F_ZERO; continue;
-                case 'z': flags |= F_NO_NEG_0; continue;
                 }
                 break;
             }