package.el asks whether I want to save modified files before package installation. How to disable this?

Question

When I run M-x package-install to install a package, I get asked whether I want to save files, that have been modified since the last save (Save file /a/b/c.txt? (y, n, !, ., q, C-r, d or C-h) in the minibuffer). I get this prompt for each modified file, and, if installing multiple packages from the *Packages* buffer, I get asked multiple times! This is incredibly frustrating, especially as the files that I am asked about have nothing to do with compilation, and could, in fact, be any files at all, including ordinary text files.

I did a bit of sleuthing, and found that, at the end of the day, package.el runs package-unpack to install a package, which runs package--compile, which runs byte-recompile-directory. I have therefore set the following in my init.el (even though I don't think I should have to do that(!)):

(setq compilation-ask-about-save nil)

No improvement.

Frankly, I thought this must be a side-effect of some customization of mine, since in no way would I consider this to be desirable behavior...until I ran emacs -Q to reproduce this without my config, and, to my surprise, ran into the very same thing. While this seems baffling, it also offers me some hope that perhaps someone has figured out a way to disable this super-annoying prompt?

Answer 1

As the help text tells you when you type C-h (as prompted by save-some-buffers, which is the function responsible for the query), you can skip all remaining queries with a simple RET or q.

I certainly don't find myself in this situation so frequently that doing that is an onerous task, so this might be sufficient for you.

p.s. compilation-ask-about-save is related to running external compiler processes, and not to elisp byte-compilation.

Edit:

One option would be binding noninteractive ("Non-nil means Emacs is running without interactive terminal.") around package--compile with advice, as byte-recompile-directory won't trigger save-some-buffers in that case; but I think that's going to have some undesirable consequences further down.

Redefining save-some-buffers for the duration seems like a safer option:

(defadvice package--compile (around no-byte-recompile-saves)
  "Inhibit `save-some-buffers' when byte-compiling packages."
  (require 'cl-lib)
  (cl-letf (((symbol-function 'save-some-buffers) 'ignore))
    ad-do-it))
(ad-activate 'package--compile)

Answer 2

I have been suffering this as well: in long Emacs sessions with multiple Tramp connections, I am prompted to save buffers in remote machines when I grep my local sources.

Since Emacs 28 (currently, this is the master branch), Emacs has added the value save-some-buffers-root for the option save-some-buffers-default-predicate.

With this value, Emacs will prompt to save only those modified buffers inside the current project. For instance, at the Emacs sources, if you call save-some-buffers from dir:

~/emacs_source/lisp

then, you'll be also prompted for a modified buffer at:

~/emacs_source/src

but you won't be prompted for a modified buffer at:

~/foodir

In case Emacs cannot find a project, then Emacs will only ask for buffers whose default-directory is in a subdir of the directory where save-some-buffers is invoked.

For example,

If you call it at:

~/foo/

you'll be prompted to save buffers at both:

~/foo/
~/foo/bar/

but you won't be prompted to save buffers at:

~/qux