From 712aad4f2db68e8f2de833662b6534c2b139a32d Mon Sep 17 00:00:00 2001
From: Irit Katriel <iritkatriel@yahoo.com>
Date: Wed, 13 Jan 2021 19:39:47 +0000
Subject: [PATCH 1/2] bpo-28146: Fix a confusing error message in str.format()

---
 Lib/test/test_unicode.py                               |  7 +++++--
 .../2021-01-13-19-34-41.bpo-28146.AZBBkH.rst           |  1 +
 Python/formatter_unicode.c                             | 10 ++++++++--
 3 files changed, 14 insertions(+), 4 deletions(-)
 create mode 100644 Misc/NEWS.d/next/Core and Builtins/2021-01-13-19-34-41.bpo-28146.AZBBkH.rst

diff --git a/Lib/test/test_unicode.py b/Lib/test/test_unicode.py
index 4f5636e1426f4d..af30478d3e510c 100644
--- a/Lib/test/test_unicode.py
+++ b/Lib/test/test_unicode.py
@@ -1225,8 +1225,11 @@ def __repr__(self):
                           0, 1, 2, 3, 4, 5, 6, 7)
 
         # string format spec errors
-        self.assertRaises(ValueError, "{0:-s}".format, '')
-        self.assertRaises(ValueError, format, "", "-")
+        sign_msg = "Sign not allowed in string format specifier"
+        self.assertRaisesRegex(ValueError, sign_msg, "{0:-s}".format, '')
+        self.assertRaisesRegex(ValueError, sign_msg, format, "", "-")
+        space_msg = "Space not allowed in string format specifier"
+        self.assertRaisesRegex(ValueError, space_msg, "{: }".format, '')
         self.assertRaises(ValueError, "{0:=s}".format, '')
 
         # Alternate formatting is not supported
diff --git a/Misc/NEWS.d/next/Core and Builtins/2021-01-13-19-34-41.bpo-28146.AZBBkH.rst b/Misc/NEWS.d/next/Core and Builtins/2021-01-13-19-34-41.bpo-28146.AZBBkH.rst
new file mode 100644
index 00000000000000..853205995f9540
--- /dev/null
+++ b/Misc/NEWS.d/next/Core and Builtins/2021-01-13-19-34-41.bpo-28146.AZBBkH.rst	
@@ -0,0 +1 @@
+Fixed a confusing error message in :func:`str.format`.
diff --git a/Python/formatter_unicode.c b/Python/formatter_unicode.c
index ed95f267d476c7..e7ec4dd5cb4d2e 100644
--- a/Python/formatter_unicode.c
+++ b/Python/formatter_unicode.c
@@ -773,8 +773,14 @@ format_string_internal(PyObject *value, const InternalFormatSpec *format,
 
     /* sign is not allowed on strings */
     if (format->sign != '\0') {
-        PyErr_SetString(PyExc_ValueError,
-                        "Sign not allowed in string format specifier");
+        if (format->sign == ' ') {
+            PyErr_SetString(PyExc_ValueError,
+                "Space not allowed in string format specifier");
+        }
+        else {
+            PyErr_SetString(PyExc_ValueError,
+                "Sign not allowed in string format specifier");
+        }
         goto done;
     }
 

From 7d1e537ddac3cd8eedb39501d3a3143a253bea78 Mon Sep 17 00:00:00 2001
From: Antoine Pitrou <antoine@python.org>
Date: Thu, 13 May 2021 22:36:01 +0200
Subject: [PATCH 2/2] Fix tense in NEWS

---
 .../Core and Builtins/2021-01-13-19-34-41.bpo-28146.AZBBkH.rst  | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/Misc/NEWS.d/next/Core and Builtins/2021-01-13-19-34-41.bpo-28146.AZBBkH.rst b/Misc/NEWS.d/next/Core and Builtins/2021-01-13-19-34-41.bpo-28146.AZBBkH.rst
index 853205995f9540..e6198819389532 100644
--- a/Misc/NEWS.d/next/Core and Builtins/2021-01-13-19-34-41.bpo-28146.AZBBkH.rst	
+++ b/Misc/NEWS.d/next/Core and Builtins/2021-01-13-19-34-41.bpo-28146.AZBBkH.rst	
@@ -1 +1 @@
-Fixed a confusing error message in :func:`str.format`.
+Fix a confusing error message in :func:`str.format`.