Ctrl+C corrupts autocomplete

[danielzgtg]

Bug report

Bug description:

1. Open the REPL
2. Type dict.c
3. Press tab twice
4. Press Ctrl + C

Expected behavior

There should be nothing after KeyboardInterrupt, and nothing after >>> like Node.js and PowerShell.

$ ./python
Python 3.15.0a0 (heads/main: future expected behavior ) [GCC 14.2.0] on linux
Type "help", "copyright", "credits" or "license" for more information.
>>> dict.c
KeyboardInterrupt
>>> 

Actual behavior

The autocomplete was not cleared, and what is a KeyboardInterrupt.copy(?

$ ./python
Python 3.15.0a0 (heads/main:e9d845b41dc, May 28 2025, 18:37:23) [GCC 14.2.0] on linux
Type "help", "copyright", "credits" or "license" for more information.
>>> dict.c
KeyboardInterrupt.copy(                                                                                                                                                               
>>> 
dict.clear(  dict.copy(

CPython versions tested on:

CPython main branch

Operating systems tested on:

Linux

Linked PRs

• gh-134869: Fix Ctrl+C corrupts REPL autocomplete #134929

[ggqlq]

This issue appears to stem from the fact that the completion menu is not reset when handling the KeyboardInterrupt exception. To address this, we can add the reset logic in the run_multiline_interactive_console function of Lib/_pyrepl/simple_interact.py.

# Lib/_pyrepl/simple_interact.py line 159 to 171
        except KeyboardInterrupt:
            r = _get_reader()
+           r.cmpltn_menu_visible = False
+           r.cmpltn_message_visible = False
+           r.cmpltn_menu = []
+           r.cmpltn_menu_end = 0
            if r.input_trans is r.isearch_trans:
                r.do_cmd(("isearch-end", [""]))
            r.pos = len(r.get_unicode())
            r.dirty = True
            r.refresh()
            console.write("\nKeyboardInterrupt\n")
            console.resetbuffer()

The completion menu state variables (cmpltn_menu_visible, cmpltn_message_visible, etc.) control the display and content of the autocomplete suggestions. Resetting them ensures that any pending completions are cleared when the user interrupts with Ctrl+C.

Here's a preview of this fix:

# Before press ctrl + c
Python 3.15.0a0 (heads/gh-134869-dirty:c6003106632, May 30 2025, 20:53:02) [GCC 12.2.0] on linux
Type "help", "copyright", "credits" or "license" for more information.
>>> list.c
list.clear(  list.copy(   list.count(

# After press ctrl + c
Python 3.15.0a0 (heads/gh-134869-dirty:c6003106632, May 30 2025, 20:53:02) [GCC 12.2.0] on linux
Type "help", "copyright", "credits" or "license" for more information.
>>> list.c
KeyboardInterrupt
>>>