gh-131430: Fix crashes on empty DELETE_WORD_BACKWARDS (^W) followed by CLEAR_TO_START (^K)

deepwzh · deepwzh · commit 413c3f99d65a · 2025-05-11T06:47:12.000Z
diff --git a/Lib/_pyrepl/commands.py b/Lib/_pyrepl/commands.py
@@ -66,7 +66,7 @@ def kill_range(self, start: int, end: int) -> None:
         b = r.buffer
         text = b[start:end]
         del b[start:end]
-        if is_kill(r.last_command):
+        if is_kill(r.last_command) and r.kill_ring:
             if start < r.pos:
                 r.kill_ring[-1] = text + r.kill_ring[-1]
             else:
diff --git a/Lib/test/test_pyrepl/test_reader.py b/Lib/test/test_pyrepl/test_reader.py
@@ -4,6 +4,7 @@
 from textwrap import dedent
 from unittest import TestCase
 from unittest.mock import MagicMock
+from _pyrepl.readline import multiline_input
 from test.support import force_colorized_test_class, force_not_colorized_test_class
 
 from .support import handle_all_events, handle_events_narrow_console
@@ -358,6 +359,59 @@ def test_setpos_from_xy_for_non_printing_char(self):
         reader.setpos_from_xy(8, 0)
         self.assertEqual(reader.pos, 7)
 
+    def test_empty_line_control_w_k(self):
+        """Test that Control-W followed by Control-K on an empty line doesn't crash."""
+        events = itertools.chain(
+            [
+                Event(evt="key", data="\x17", raw=bytearray(b"\x17")),  # Control-W
+                Event(evt="key", data="\x0b", raw=bytearray(b"\x0b")),  # Control-K
+            ],
+        )
+        reader, _ = handle_all_events(events)
+        self.assert_screen_equal(reader, "", clean=True)
+        self.assertEqual(reader.pos, 0)
+
+    def test_control_w_delete_word(self):
+        """Test Control-W delete word"""
+        def test_with_text(text: str, expected: list[str], before_pos: int, after_pos: int):
+            events = itertools.chain(
+                code_to_events(text) if len(text) else [],
+                [Event(evt="key", data="left", raw=bytearray(b"\x1b[D"))] * (len(text) - before_pos),  # Move cursor to specified position
+                [
+                    Event(evt="key", data="\x17", raw=bytearray(b"\x17")), # Control-W
+                ],
+            )
+            reader, _ = handle_all_events(events)
+            self.assertEqual(reader.screen, expected)
+            self.assertEqual(reader.pos, after_pos)
+
+        test_with_text("", [], 0, 0)
+        test_with_text("a", [""], 1, 0)
+        test_with_text("abc", [""], 3, 0)
+        test_with_text("abc def", ["def"], 4, 0)
+        test_with_text("abc def", ["abc "], 7, 4)
+        test_with_text("def xxx():xxx\n    ", ["def xxx():"], 18, 10)
+
+    def test_control_k_delete_to_eol(self):
+        """Test Control-K delete from cursor to end of line"""
+        def test_with_text(text: str, pos: int, expected: list[str]):
+            events = itertools.chain(
+                code_to_events(text) if len(text) else [],
+                [Event(evt="key", data="left", raw=bytearray(b"\x1b[D"))] * (len(text) - pos),  # Move cursor to specified position
+                [
+                    Event(evt="key", data="\x0b", raw=bytearray(b"\x0b")),  # Control-K
+                ],
+            )
+            reader, _ = handle_all_events(events)
+            self.assertEqual(reader.screen, expected)
+            self.assertEqual(reader.pos, pos)
+
+        test_with_text("", 0, [""])
+        test_with_text("a", 0, [""])
+        test_with_text("abc", 1, ["a"])
+        test_with_text("abc def", 4, ["abc "])
+        test_with_text("def xxx():xxx\n    pass", 10, ["def xxx():", "    pass"])
+
 @force_colorized_test_class
 class TestReaderInColor(ScreenEqualMixin, TestCase):
     def test_syntax_highlighting_basic(self):
diff --git a/Misc/NEWS.d/next/Core_and_Builtins/2025-05-11-06-44-10.gh-issue-131430.wbtIcQ.rst b/Misc/NEWS.d/next/Core_and_Builtins/2025-05-11-06-44-10.gh-issue-131430.wbtIcQ.rst
@@ -0,0 +1,3 @@
+Fix crashes on an empty DELETE_WORD_BACKWARDS (^W) followed by
+CLEAR_TO_START (^K). Added comprehensive test cases for both Control-W and
+Control-K functionality.

Original file line number	Diff line number	Diff line change
`@@ -0,0 +1,3 @@`
	`1`	`+Fix crashes on an empty DELETE_WORD_BACKWARDS (^W) followed by`
	`2`	`+CLEAR_TO_START (^K). Added comprehensive test cases for both Control-W and`
	`3`	`+Control-K functionality.`