Subject: bug#70526: 29.2; package-vc-upgrade failed with error message "File is not under version control"

From: "Yi Yue" <[email-masked]>
Date: Tue, 23 Apr 2024 10:51:18 +0900

Hi all:

I encountered the following Backtrace information when invoking
`package-vc-upgrade'.

Debugger entered--Lisp error: (error "File is not under version control")
&nbsp; error("File is not under version control")
&nbsp; vc-deduce-fileset-1(t nil nil)
&nbsp; vc-deduce-fileset(t)
&nbsp; vc-pull()
&nbsp; ......

After some edebug debugging and reading the source code, I found that
this error occurs if the buffer where `package-vc-upgrade' is called is
not under a git repository. Additionally, if the current buffer of the
command invocation does not correspond to a specific file, then the
command can execute normally.

After reading the implementation of `package-vc-upgrade', I found that it
binds `default-directory' to the package's path. However, the internally
called `vc-pull' function, which uses `vc-deduce-fileset-1', first
utilizes `buffer-file-name' instead of `default-directory' to fetch
version control backend related information, which leads to this error.

In my past usage, I did not encounter this error, probably because I
usually invoked it within a file buffer under a git repository, or used
the command in a buffer provided by `list-packages'. Here is one
solution I used:

(when (eq emacs-major-version 29)
&nbsp; (defun yy/package-vc-upgrade-advice (upfun pkg-desc)
&nbsp; &nbsp; (with-temp-buffer
&nbsp; &nbsp; &nbsp; (funcall upfun pkg-desc)))
&nbsp; (advice-add 'package-vc-upgrade :around 'yy/package-vc-upgrade-advice))

In a minimal environment with emacs -Q, the following steps can
reproduce my issue:

;; a simple package by purcell
(package-vc-install "https://github.com/purcell/unfill")
;; then try to upgrade it in a buffer that buffer-file-name is not nil
;; and the file is not under Git version control system.
M-x package-vc-upgrade unfill RET
;; now the error may occurs

Regards

YI YUE