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gh-131189: Fix "msvcrt" import warning on Linux when "_ctypes" is not available. #131201

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merged 1 commit into from
Jul 15, 2025
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gh-131189: Fix "msvcrt" import warning on Linux when "_ctypes" is not available. #131201

merged 1 commit into from
Jul 15, 2025

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plashchynski
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@plashchynski plashchynski commented Mar 13, 2025 •
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On Linux, compiling without "libffi" causes a misleading warning
"No module named 'msvcrt'" when launching PyREPL.

@plashchynski
Fix "msvcrt" import warning on Linux when "_ctypes" is not available.
56364ce 
On Linux, compiling without "libffi" causes a
"No module named 'msvcrt'" warning when launching PyREPL.
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bedevere-app bot commented Mar 13, 2025

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If this change has little impact on Python users, wait for a maintainer to apply the skip news label instead.

@bedevere-app bedevere-app bot mentioned this pull request Mar 13, 2025
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sobolevn
sobolevn reviewed Mar 14, 2025
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I cannot recreate the same setup as you have, can you please share what happens with this change in place?

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@sobolevn steps to reproduce on a fresh Ubuntu Server 24.04.2 setup:

sudo apt install build-essential
git clone https://github.com/python/cpython.git
cd cpython
./configure
make

Then:

./python

shows:

Python 3.14.0a5+ (heads/main:c497f83ad85, Mar 14 2025, 09:42:58) [GCC 13.3.0] on linux
Type "help", "copyright", "credits" or "license" for more information.
warning: can't use pyrepl: No module named 'msvcrt'
>>>

Here's a full log.

with changes in this PR, it shows the following with the same setup:

Python 3.14.0a5+ (heads/fix_msvcrt_warning_on_linux:56364cef29, Mar 14 2025, 09:49:25) [GCC 13.3.0] on linux
Type "help", "copyright", "credits" or "license" for more information.
warning: can't use pyrepl: No module named '_ctypes'
>>>

Here's a full log.

warning: can't use pyrepl: No module named 'msvcrt'

this warning is misleading, because msvcrt is available only on NT systems.

warning: can't use pyrepl: No module named '_ctypes'

this warning is consistent with the warning make shows for missing necessary bits:

The necessary bits to build these optional modules were not found:
_bz2                      _ctypes                   _ctypes_test           
_curses                   _curses_panel             _dbm                   
_gdbm                     _hashlib                  _lzma                  
_ssl                      _tkinter                  _uuid                  
readline                  zlib                                             
To find the necessary bits, look in configure.ac and config.log.

sobolevn
sobolevn approved these changes Mar 14, 2025
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Thanks, it is clear now! LGTM. However, I am not the module's maintainer, let's wait for them to make the final decision :)

vstinner
vstinner approved these changes Jun 18, 2025
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LGTM

@ambv ambv merged commit f320c95 into python:main Jul 15, 2025
54 checks passed
@ambv ambv added the needs backport to 3.14 bugs and security fixes label Jul 15, 2025
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Thanks @plashchynski for the PR, and @ambv for merging it 🌮🎉.. I'm working now to backport this PR to: 3.14.
🐍🍒⛏🤖

miss-islington pushed a commit to miss-islington/cpython that referenced this pull request Jul 15, 2025
@plashchynski @miss-islington
pythongh-131189: Fix "msvcrt" import warning on Linux when "_ctypes" …
36da690 
…is not available. (pythonGH-131201)

Fix "msvcrt" import warning on Linux when "_ctypes" is not available.

On Linux, compiling without "libffi" causes a
"No module named 'msvcrt'" warning when launching PyREPL.
(cherry picked from commit f320c95)

Co-authored-by: Dzmitry Plashchynski <plashchynski@gmail.com>
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bedevere-app bot commented Jul 15, 2025

GH-136668 is a backport of this pull request to the 3.14 branch.

@bedevere-app bedevere-app bot removed the needs backport to 3.14 bugs and security fixes label Jul 15, 2025
ambv pushed a commit that referenced this pull request Jul 15, 2025
@miss-islington @plashchynski
[3.14] gh-131189: Fix "msvcrt" import warning on Linux when "_ctypes"…
1154773 
… is not available. (GH-131201) (GH-136668)

Fix "msvcrt" import warning on Linux when "_ctypes" is not available.

On Linux, compiling without "libffi" causes a
"No module named 'msvcrt'" warning when launching PyREPL.
(cherry picked from commit f320c95)

Co-authored-by: Dzmitry Plashchynski <plashchynski@gmail.com>
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@pablogsal pablogsal Awaiting requested review from pablogsal pablogsal is a code owner

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@ambv ambv Awaiting requested review from ambv ambv is a code owner

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