gh-153480: Stop IDLE crashing when a file open in the editor is deleted by tonghuaroot · Pull Request #153481 · python/cpython

tonghuaroot · 2026-07-10T04:52:25Z

EditorWindow.focus_in_event runs on every <FocusIn> event and calls last_mtime, which called os.path.getmtime(self.io.filename) with no error handling. When the open file had been deleted or renamed by another program, refocusing the editor window let a FileNotFoundError escape the Tk event handler and broke the modified-on-disk reload check.

last_mtime now guards getmtime with try/except OSError and returns the last known mtime, so focus_in_event sees no change and does not prompt to reload a file that is gone. The regression test drives last_mtime as an unbound method against a duck-typed stub (no GUI) for both the deleted-file and no-filename cases.

Issue: IDLE fails to start or raises when an editor window's file does not exist #153480

… deleted EditorWindow.focus_in_event calls last_mtime on every <FocusIn> event, which passed the open file path to os.path.getmtime with no guard. When another program deleted or renamed the file, refocusing the IDLE window let a FileNotFoundError escape the Tk event handler. last_mtime now returns the last known mtime when the path is inaccessible, so refocusing no longer raises and does not prompt to reload a file that is gone.

serhiy-storchaka

Thanks for the PR — the FocusIn traceback is real, but the fallback return self.mtime runs too early in one case.

EditorWindow.__init__ calls io.set_filename(filename) for a filename that does not exist yet (python -m idlelib new.py), which goes set_saved(True) → last_mtime() before self.mtime is assigned at line 315. On main that already aborts IDLE at startup with FileNotFoundError (a regression from gh-94523, shipped in 3.13.15, 3.14.7 and 3.15.0b1); with this patch it aborts with AttributeError: 'EditorWindow' object has no attribute 'mtime' instead.

last_mtime() should return None when there is no file or it cannot be stat'ed (not 0, which is a valid mtime on filesystems that do not keep timestamps). A new file then opens with mtime = None, and a file that is created by another program after opening still triggers the existing reload prompt.

When the file was there and is now gone (self.mtime is not None and mtime is None), "modified by another program, reload?" is the wrong question — reloading can only fail. Ask instead what to do with the buffer: Close, Save As or Ignore, with Save As as the default. tkinter.simpledialog.SimpleDialog(..., buttons=('Close', 'Save As', 'Ignore'), default=1, cancel=2) gives such a box; .go() returns the button index. Close → self.close(). Save As → self.io.save_as(event). Ignore → set self.mtime = None and self.set_saved(False), so the window is marked as unsaved but the question is not repeated on the next FocusIn.

This is an approximate plan; details can be changed later.

Please add a test for the not-yet-existing filename (a SimpleNamespace stub without mtime is enough to catch the AttributeError), expect None in test_deleted_file_does_not_raise, and tests for the deleted-file branch with the dialog mocked.

Two smaller things: the NEWS file belongs in Misc/NEWS.d/next/IDLE/, not Library/, and open(p, 'w').close() in the test can be Path(p).touch() or a with.

bedevere-app · 2026-09-15T15:06:02Z

A Python core developer has requested some changes be made to your pull request before we can consider merging it. If you could please address their requests along with any other requests in other reviews from core developers that would be appreciated.

Once you have made the requested changes, please leave a comment on this pull request containing the phrase I have made the requested changes; please review again. I will then notify any core developers who have left a review that you're ready for them to take another look at this pull request.

last_mtime() now returns None for a missing or un-stat-able file, which also fixes the startup path where it runs before self.mtime is set. The vanished-file case now offers Close, Save As or Ignore instead of a reload that could only fail. Tests updated; NEWS moved to IDLE/.

tonghuaroot · 2026-09-17T04:52:28Z

Done: last_mtime() now returns None for a missing or un-stat-able file (this also fixes the startup path where it runs before self.mtime is set), and the vanished-file case shows the Close/Save As/Ignore dialog. Tests and the NEWS (moved to IDLE/) updated.

I have made the requested changes; please review again

bedevere-app · 2026-09-17T04:52:34Z

Thanks for making the requested changes!

@serhiy-storchaka: please review the changes made to this pull request.

serhiy-storchaka

Thanks, this works for me now: starting with a not yet existing file, Ignore, reload after the file is recreated, Close. One remaining problem with a cancelled Save As, see the comment.

serhiy-storchaka · 2026-09-17T08:49:14Z

+        elif choice == 1:
+            self.io.save_as(event)
+        else:
+            self.mtime = None
+            self.set_saved(False)


If Save As is cancelled, self.mtime keeps the old value, and closing the dialog gives the focus back to the editor, so the dialog pops up again immediately — I got 11 dialogs in 3 seconds. Also, set_saved(False) is not needed: if the buffer was modified, it is already unsaved, and if it was not (e.g. a log file opened for viewing), there is nothing to lose by closing the window. A successful Save As sets mtime again via set_saved(True).

Suggested change

elif choice == 1:

self.io.save_as(event)

else:

self.mtime = None

self.set_saved(False)

else:

self.mtime = None

if choice == 1:

self.io.save_as(event)

Please adjust the tests accordingly.

serhiy-storchaka · 2026-09-17T08:50:54Z

+IDLE no longer fails with a traceback when a file open in the editor is
+deleted or renamed by another program; refocusing the window now offers to
+close it, save the buffer as a new file, or keep editing.  Opening a
+not-yet-created file no longer prevents IDLE from starting.


Suggested change

IDLE no longer fails with a traceback when a file open in the editor is

deleted or renamed by another program; refocusing the window now offers to

close it, save the buffer as a new file, or keep editing. Opening a

not-yet-created file no longer prevents IDLE from starting.

Fix IDLE failing to start when opening a file which does not exist yet.

Fix a traceback when a file open in the IDLE editor is deleted by another

program; IDLE now asks whether to close the window, save the file elsewhere,

or ignore it.

A cancelled Save As kept the old mtime and reprompted on every focus. Forget the mtime for both Save As and Ignore; a successful Save As restores it via set_saved(True). Reword the NEWS per review.

tonghuaroot · 2026-09-17T10:38:05Z

Fixed: the dialog now forgets the mtime for both Save As and Ignore, so a cancelled Save As no longer reprompts (a successful one restores it via set_saved(True)). Dropped the set_saved(False), applied your NEWS wording, and adjusted the tests.

I have made the requested changes; please review again

bedevere-app · 2026-09-17T10:38:09Z

Thanks for making the requested changes!

@serhiy-storchaka: please review the changes made to this pull request.

serhiy-storchaka

Found one more case: modify the file, delete it, get the focus back, choose Close. See the comment.

serhiy-storchaka · 2026-09-17T11:21:49Z

+            buttons=('Close', 'Save As', 'Ignore'),
+            default=1,
+            cancel=2)
+        choice = dialog.go()


With a modified buffer, Close asks whether to save, and the FocusIn event queued when this dialog closed is delivered inside that message box, so the dialog is shown a second time (and currently crashes on the message box's grab, a separate tkinter bug). Set self.mtime = None before showing the dialog, for all choices; a successful Save As sets it again.

bedevere-app · 2026-09-17T11:21:56Z

A Python core developer has requested some changes be made to your pull request before we can consider merging it. If you could please address their requests along with any other requests in other reviews from core developers that would be appreciated.

Once you have made the requested changes, please leave a comment on this pull request containing the phrase I have made the requested changes; please review again. I will then notify any core developers who have left a review that you're ready for them to take another look at this pull request.

tonghuaroot requested a review from terryjreedy as a code owner July 10, 2026 04:52

bedevere-app Bot added the awaiting review label Jul 10, 2026

bedevere-app Bot mentioned this pull request Jul 10, 2026

IDLE fails to start or raises when an editor window's file does not exist #153480

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Merge branch 'main' into idlelib-editor-last-mtime-oserror

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serhiy-storchaka requested changes Sep 15, 2026

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bedevere-app Bot requested a review from serhiy-storchaka September 17, 2026 04:52

Fix end-of-file newline in editor.py and test_editor.py

e84056b

serhiy-storchaka reviewed Sep 17, 2026

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pythongh-153480: Clear mtime in the deleted-file dialog before Save As

ceffab2

A cancelled Save As kept the old mtime and reprompted on every focus. Forget the mtime for both Save As and Ignore; a successful Save As restores it via set_saved(True). Reword the NEWS per review.

bedevere-app Bot requested a review from serhiy-storchaka September 17, 2026 10:38

serhiy-storchaka requested changes Sep 17, 2026

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bedevere-app Bot removed the awaiting change review label Sep 17, 2026

bedevere-app Bot added the awaiting changes label Sep 17, 2026

serhiy-storchaka mentioned this pull request Sep 17, 2026

tkinter.simpledialog: KeyError when a dialog is opened while a window not created by tkinter holds the grab #157676

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gh-153480: Stop IDLE crashing when a file open in the editor is deleted - #153481

gh-153480: Stop IDLE crashing when a file open in the editor is deleted#153481
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