gh-146044: Fix ctrl-w (unix-word-rubout) to use whitespace word boundaries

Lib/_pyrepl/commands.py

@@ -169,7 +169,7 @@ class unix_word_rubout(KillCommand):
     def do(self) -> None:
         r = self.reader
         for i in range(r.get_arg()):
-            self.kill_range(r.bow(), r.pos)
+            self.kill_range(r.bow_whitespace(), r.pos)
 
 
 class kill_word(KillCommand):

Lib/_pyrepl/reader.py

@@ -417,6 +417,22 @@ def bow(self, p: int | None = None) -> int:
             p -= 1
         return p + 1
 
+    def bow_whitespace(self, p: int | None = None) -> int:
+        """Return the 0-based index of the whitespace-delimited word break
+        preceding p most immediately.
+
+        p defaults to self.pos; only whitespace is considered a word
+        boundary, matching the behavior of unix-word-rubout in bash/readline."""
+        if p is None:
+            p = self.pos
+        b = self.buffer
+        p -= 1
+        while p >= 0 and b[p] in (" ", "\n"):
+            p -= 1
+        while p >= 0 and b[p] not in (" ", "\n"):
+            p -= 1
+        return p + 1
+
     def eow(self, p: int | None = None) -> int:
         """Return the 0-based index of the word break following p most
         immediately.

Lib/test/test_pyrepl/test_reader.py

@@ -558,3 +558,47 @@ def test_control_characters(self):
         reader, _ = handle_all_events(events)
         self.assert_screen_equal(reader, 'flag = "🏳️\\u200d🌈"', clean=True)
         self.assert_screen_equal(reader, 'flag {o}={z} {s}"🏳️\\u200d🌈"{z}'.format(**colors))
+
+
+class TestBowWhitespace(TestCase):
+    def test_bow_whitespace_stops_at_whitespace(self):
+        # GH#146044
+        # unix-word-rubout (ctrl-w) should use whitespace boundaries,
+        # not punctuation boundaries like bow() does
+        reader = prepare_reader(prepare_console([]))
+        reader.buffer = list("foo.bar baz")
+        reader.pos = len(reader.buffer)  # cursor at end
+
+        # bow_whitespace from end should jump to start of "baz"
+        result = reader.bow_whitespace()
+        self.assertEqual(result, 8)  # index of 'b' in "baz"
+
+    def test_bow_whitespace_includes_punctuation_in_word(self):
+        # GH#146044
+        reader = prepare_reader(prepare_console([]))
+        reader.buffer = list("foo.bar(baz) qux")
+        reader.pos = 12  # cursor after ")"
+
+        # bow_whitespace should treat "foo.bar(baz)" as one word
+        result = reader.bow_whitespace()
+        self.assertEqual(result, 0)
+
+    def test_bow_stops_at_punctuation(self):
+        # Verify existing bow() still uses syntax_table (punctuation boundary)
+        reader = prepare_reader(prepare_console([]))
+        reader.buffer = list("foo.bar baz")
+        reader.pos = len(reader.buffer)
+
+        result = reader.bow()
+        self.assertEqual(result, 8)  # same — "baz" is all word chars
+
+    def test_bow_vs_bow_whitespace_difference(self):
+        # The key difference: bow() stops at '.', bow_whitespace() does not
+        reader = prepare_reader(prepare_console([]))
+        reader.buffer = list("foo.bar")
+        reader.pos = len(reader.buffer)
+
+        # bow() stops at '.' → returns index of 'b' in "bar"
+        self.assertEqual(reader.bow(), 4)
+        # bow_whitespace() treats entire "foo.bar" as one word
+        self.assertEqual(reader.bow_whitespace(), 0)

Misc/NEWS.d/next/Library/2026-03-20-00-00-01.gh-issue-146044.WsCtrl.rst

@@ -0,0 +1,3 @@
+Fix ``unix-word-rubout`` (Ctrl-W) in the REPL to use whitespace-only word
+boundaries, matching bash/readline behavior. Previously it used
+syntax-table boundaries which treated punctuation as word separators.