From ef6f92a2a63fd83d62d9a431b2c3133a9a069ea0 Mon Sep 17 00:00:00 2001
From: Chris Eibl <138194463+chris-eibl@users.noreply.github.com>
Date: Fri, 2 Jan 2026 16:17:45 +0100
Subject: [PATCH] gh-139262: Prevent swallowing REPL input on Windows
 (GH-139263)
MIME-Version: 1.0
Content-Type: text/plain; charset=utf8
Content-Transfer-Encoding: 8bit

Co-authored-by: Łukasz Langa <lukasz@langa.pl>
---
 Lib/_pyrepl/windows_console.py                | 11 +++++++-
 Lib/test/test_pyrepl/test_windows_console.py  | 26 +++++++++++++++++++
 ...-09-23-16-41-21.gh-issue-139262.RO0E98.rst |  2 ++
 3 files changed, 38 insertions(+), 1 deletion(-)
 create mode 100644 Misc/NEWS.d/next/Library/2025-09-23-16-41-21.gh-issue-139262.RO0E98.rst

diff --git a/Lib/_pyrepl/windows_console.py b/Lib/_pyrepl/windows_console.py
index a703a061e8ed..303af8a354ff 100644
--- a/Lib/_pyrepl/windows_console.py
+++ b/Lib/_pyrepl/windows_console.py
@@ -554,7 +554,7 @@ class WindowsConsole(Console):
                 e.data += ch
         return e
 
-    def wait(self, timeout: float | None) -> bool:
+    def wait_for_event(self, timeout: float | None) -> bool:
         """Wait for an event."""
         if timeout is None:
             timeout = INFINITE
@@ -567,6 +567,15 @@ class WindowsConsole(Console):
             return False
         return True
 
+    def wait(self, timeout: float | None) -> bool:
+        """
+        Wait for events on the console.
+        """
+        return (
+            not self.event_queue.empty()
+            or self.wait_for_event(timeout)
+        )
+
     def repaint(self) -> None:
         raise NotImplementedError("No repaint support")
 
diff --git a/Lib/test/test_pyrepl/test_windows_console.py b/Lib/test/test_pyrepl/test_windows_console.py
index 065706472e52..3587b834f3cd 100644
--- a/Lib/test/test_pyrepl/test_windows_console.py
+++ b/Lib/test/test_pyrepl/test_windows_console.py
@@ -590,6 +590,32 @@ class WindowsConsoleGetEventTests(TestCase):
                          Event(evt='key', data='up', raw=bytearray(b'\x1b[A')))
         self.assertEqual(self.mock.call_count, 3)
 
+    # All tests above assume that there is always keyboard data to read,
+    # because for simplicity we just use
+    # self.console.wait = MagicMock(return_value=True)
+    def test_wait_empty(self):
+        console = WindowsConsole(encoding='utf-8')
+        console.wait_for_event = MagicMock(return_value=True)
+        self.assertTrue(console.event_queue.empty())
+        timeout = 2.0
+        self.assertTrue(console.wait(timeout))
+        self.assertEqual(console.wait_for_event.call_count, 1)
+        self.assertEqual(console.wait_for_event.mock_calls[0], call(timeout))
+
+        timeout = 1.1
+        console.wait_for_event = MagicMock(return_value=False)
+        self.assertFalse(console.wait(timeout))
+        self.assertEqual(console.wait_for_event.call_count, 1)
+        self.assertEqual(console.wait_for_event.mock_calls[0], call(timeout))
+
+    def test_wait_not_empty(self):
+        console = WindowsConsole(encoding='utf-8')
+        console.wait_for_event = MagicMock(return_value=True)
+        console.event_queue.push(b"a")
+        self.assertFalse(console.event_queue.empty())
+        self.assertTrue(console.wait(0.0))
+        self.assertEqual(console.wait_for_event.call_count, 0)
+
 
 if __name__ == "__main__":
     unittest.main()
diff --git a/Misc/NEWS.d/next/Library/2025-09-23-16-41-21.gh-issue-139262.RO0E98.rst b/Misc/NEWS.d/next/Library/2025-09-23-16-41-21.gh-issue-139262.RO0E98.rst
new file mode 100644
index 000000000000..628fa0e0d53c
--- /dev/null
+++ b/Misc/NEWS.d/next/Library/2025-09-23-16-41-21.gh-issue-139262.RO0E98.rst
@@ -0,0 +1,2 @@
+Some keystrokes can be swallowed in the new ``PyREPL`` on Windows,
+especially when used together with the ALT key. Fix by Chris Eibl.
-- 
2.47.3