From f4f813338736aecc9285a9408cb8a07eaeb0e373 Mon Sep 17 00:00:00 2001
From: Frazer McLean <frazer@frazermclean.co.uk>
Date: Sat, 8 Oct 2022 00:24:17 +0200
Subject: [PATCH] GH-83901: Improve Signature.bind error message for missing
 keyword-only params (#95347)

Fixes GH-83901
---
 Lib/inspect.py                                            | 8 ++++++--
 Lib/test/test_inspect.py                                  | 3 ++-
 .../Library/2022-07-27-19-47-51.gh-issue-83901.OSw06c.rst | 1 +
 3 files changed, 9 insertions(+), 3 deletions(-)
 create mode 100644 Misc/NEWS.d/next/Library/2022-07-27-19-47-51.gh-issue-83901.OSw06c.rst

diff --git a/Lib/inspect.py b/Lib/inspect.py
index 585875a30c3..f6750c3b211 100644
--- a/Lib/inspect.py
+++ b/Lib/inspect.py
@@ -3102,8 +3102,12 @@ def _bind(self, args, kwargs, *, partial=False):
                             parameters_ex = (param,)
                             break
                         else:
-                            msg = 'missing a required argument: {arg!r}'
-                            msg = msg.format(arg=param.name)
+                            if param.kind == _KEYWORD_ONLY:
+                                argtype = ' keyword-only'
+                            else:
+                                argtype = ''
+                            msg = 'missing a required{argtype} argument: {arg!r}'
+                            msg = msg.format(arg=param.name, argtype=argtype)
                             raise TypeError(msg) from None
             else:
                 # We have a positional argument to process
diff --git a/Lib/test/test_inspect.py b/Lib/test/test_inspect.py
index 61fed323dce..cfc6e411ea6 100644
--- a/Lib/test/test_inspect.py
+++ b/Lib/test/test_inspect.py
@@ -3898,7 +3898,8 @@ def test(foo, *, bar):
             self.call(test, 1, bar=2, spam='ham')
 
         with self.assertRaisesRegex(TypeError,
-                                     "missing a required argument: 'bar'"):
+                                     "missing a required keyword-only "
+                                     "argument: 'bar'"):
             self.call(test, 1)
 
         def test(foo, *, bar, **bin):
diff --git a/Misc/NEWS.d/next/Library/2022-07-27-19-47-51.gh-issue-83901.OSw06c.rst b/Misc/NEWS.d/next/Library/2022-07-27-19-47-51.gh-issue-83901.OSw06c.rst
new file mode 100644
index 00000000000..da407905a88
--- /dev/null
+++ b/Misc/NEWS.d/next/Library/2022-07-27-19-47-51.gh-issue-83901.OSw06c.rst
@@ -0,0 +1 @@
+Improve :meth:`Signature.bind <inspect.Signature.bind>` error message for missing keyword-only arguments.