gh-133400: Fixed Ctrl+D (^D) behavior in :mod:_pyrepl module

Author: deepwzh

Lib/_pyrepl/commands.py

@@ -421,6 +421,9 @@ def do(self) -> None:
             r.update_screen()
             r.console.finish()
             raise EOFError
+        elif "\n" in b and self.event[-1] == "\004":
+            self.finish = True
+
         for i in range(r.get_arg()):
             if r.pos != len(b):
                 del b[r.pos]

Lib/test/test_pyrepl/test_pyrepl.py

@@ -1610,3 +1610,43 @@ def test_prompt_after_help(self):
         # Extra stuff (newline and `exit` rewrites) are necessary
         # because of how run_repl works.
         self.assertNotIn(">>> \n>>> >>>", cleaned_output)
+
+class TestPyReplCtrlD(TestCase):
+    def prepare_reader(self, events):
+        console = FakeConsole(events)
+        config = ReadlineConfig(readline_completer=None)
+        reader = ReadlineAlikeReader(console=console, config=config)
+        return reader
+
+    def test_ctrl_d_empty_buffer(self):
+        """Test that pressing Ctrl+D on empty buffer exits the program"""
+        events = [
+            Event(evt="key", data="\x04", raw=bytearray(b"\x04")),  # Ctrl+D
+        ]
+        reader = self.prepare_reader(events)
+        with self.assertRaises(EOFError):
+            multiline_input(reader)
+
+    def test_ctrl_d_multiline_mode(self):
+        """Test that pressing Ctrl+D in multiline mode exits multiline mode"""
+        events = itertools.chain(
+            code_to_events("def f():\n"),  # Enter multiline mode
+            [
+                Event(evt="key", data="\x04", raw=bytearray(b"\x04")),  # Ctrl+D
+            ],
+        )
+        reader = self.prepare_reader(events)
+        output = multiline_input(reader)
+        self.assertEqual(output, "def f():\n    ")  # Should return current input
+
+    def test_ctrl_d_single_line(self):
+        """Test that pressing Ctrl+D in single line mode deletes current character"""
+        events = itertools.chain(
+            code_to_events("hello"),
+            [Event(evt="key", data="left", raw=bytearray(b"\x1bOD"))],  # move left
+            [Event(evt="key", data="\x04", raw=bytearray(b"\x04"))],    # Ctrl+D
+            code_to_events("\n"),
+        )
+        reader = self.prepare_reader(events)
+        output = multiline_input(reader)
+        self.assertEqual(output, "hell")  # Should delete the last character

Misc/NEWS.d/next/Core_and_Builtins/2025-05-11-09-40-19.gh-issue-133400.zkWla8.rst

@@ -0,0 +1,3 @@
+Fixed Ctrl+D (^D) behavior in _pyrepl module: Now properly exits multiline
+mode when pressed in multiline section. Added test cases to verify the
+behavior in both multiline and single line modes.