python.el has a feature whereby the editor will progressively present the python code lines that the user is stepping through in a pdb session in a python buffer (or any comint buffer to which the user has added the filter functions). The python.el pdb tracking provisions includes a function, `python-pdbtrack-set-tracked-buffer()`, which registers python code buffers that were created to visit files for pdbtracking for subsequent deletion (the buffers, not the files) after the pdb session concludes. The problem is that this provision sometimes registers buffers that were present in the editing session before the pdbtracking session, so that pdbtracking sometimes causes pdbtracked buffers to be deleted when it shouldn't.
I'm unsure what exact conditions lead to the problem, but I'm pretty sure that `python-pdbtrack-set-tracked-buffer()` uses the wrong buffer-finding function. Instead of using `get-file-buffer()`, it should be using `find-buffer-visiting()`. I believe that this will solve the problem.
Here's a diff of python.el from the emacs-26.2.90 branch with my suggested change applied. (The same patch would obtain for the master branch):
diff --git a/lisp/progmodes/python.el b/lisp/progmodes/python.el
index 38dcc823d0..151b27aa80 100644
--- a/lisp/progmodes/python.el
+++ b/lisp/progmodes/python.el
@@ -3717,7 +3717,7 @@ python-pdbtrack-set-tracked-buffer
Returns the tracked buffer."
(let* ((file-name-prospect (concat (file-remote-p default-directory)
file-name))
- (file-buffer (get-file-buffer file-name-prospect)))
+ (file-buffer (find-buffer-visiting file-name-prospect)))
(if file-buffer
(setq python-pdbtrack-tracked-buffer file-buffer)
(cond
I have verified that pdbtracking will delete some buffers that were created just for tracking and keep some buffers that were present before tracking, but haven't used it long enough to be sure it will do the right thing with all buffers. But I'm pretty sure that find-buffer-visiting should be used instead of get-file-buffer, so am pretty confident that this is a proper change.
Ken Manheimer
In GNU Emacs 26.2 (build 1, x86_64-apple-darwin18.2.0, NS appkit-1671.20 Version 10.14.3 (Build 18D109)) of 2019-04-12 built on
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In GNU Emacs 26.2 (build 1, x86_64-a"
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