From a29998a06bf75264c3faaeeec4584a5f75b45a1f Mon Sep 17 00:00:00 2001
From: Nikita Sobolev <mail@sobolevn.me>
Date: Tue, 5 Mar 2024 12:14:18 +0300
Subject: [PATCH] gh-116325: Raise `SyntaxError` rather than `IndexError` on
 ForwardRef with empty string arg (#116341)

---
 Lib/test/test_typing.py                                     | 6 ++++++
 Lib/typing.py                                               | 2 +-
 .../Library/2024-03-05-02-09-18.gh-issue-116325.FmlBYv.rst  | 2 ++
 3 files changed, 9 insertions(+), 1 deletion(-)
 create mode 100644 Misc/NEWS.d/next/Library/2024-03-05-02-09-18.gh-issue-116325.FmlBYv.rst

diff --git a/Lib/test/test_typing.py b/Lib/test/test_typing.py
index dbbbe63e95a..912384ab6bf 100644
--- a/Lib/test/test_typing.py
+++ b/Lib/test/test_typing.py
@@ -5867,6 +5867,12 @@ class ForwardRefTests(BaseTestCase):
         with self.assertRaises(SyntaxError):
             get_type_hints(foo)
 
+    def test_syntax_error_empty_string(self):
+        for form in [typing.List, typing.Set, typing.Type, typing.Deque]:
+            with self.subTest(form=form):
+                with self.assertRaises(SyntaxError):
+                    form['']
+
     def test_name_error(self):
 
         def foo(a: 'Noode[T]'):
diff --git a/Lib/typing.py b/Lib/typing.py
index 2cb4a714ea3..cca9525d632 100644
--- a/Lib/typing.py
+++ b/Lib/typing.py
@@ -880,7 +880,7 @@ class ForwardRef(_Final, _root=True):
         # If we do `def f(*args: *Ts)`, then we'll have `arg = '*Ts'`.
         # Unfortunately, this isn't a valid expression on its own, so we
         # do the unpacking manually.
-        if arg[0] == '*':
+        if arg.startswith('*'):
             arg_to_compile = f'({arg},)[0]'  # E.g. (*Ts,)[0] or (*tuple[int, int],)[0]
         else:
             arg_to_compile = arg
diff --git a/Misc/NEWS.d/next/Library/2024-03-05-02-09-18.gh-issue-116325.FmlBYv.rst b/Misc/NEWS.d/next/Library/2024-03-05-02-09-18.gh-issue-116325.FmlBYv.rst
new file mode 100644
index 00000000000..aec4ee79b59
--- /dev/null
+++ b/Misc/NEWS.d/next/Library/2024-03-05-02-09-18.gh-issue-116325.FmlBYv.rst
@@ -0,0 +1,2 @@
+:mod:`typing`: raise :exc:`SyntaxError` instead of :exc:`AttributeError`
+on forward references as empty strings.