--- Begin Message ---
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Subject: |
[PATCH] Keep project's exec-path during with-temp-buffer call |
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Date: |
Wed, 28 Aug 2024 00:13:25 +0100 |
Tags: patch
`with-temp-buffer' doesn't respect buffer-local environment variables,
`exec-path' in this case. Which results in executables not being found,
or the wrong versions of executables being picked up. E.g. if
environment variable is modified via .dir-local file or direnv/envrc
package.
I see that this function tries to be remote-host friendly (uses
`process-file') so I tried to ensure that this patch doesn't break this
effort, but I'm not sure that I understand the machinery behind TRAMP
correctly. So please consider this aspect from your side.
This patch shouldn't interfere with TRAMP, if I understand
`process-file`s doc correctly:
If a file name handler is invoked, it determines the program to run
based on the first argument PROGRAM. For instance, suppose that a
handler for remote files is invoked. Then the path that is used
for searching for the program might be different from ‘exec-path’.
In GNU Emacs 30.0.60 (build 1, x86_64-pc-linux-gnu, GTK+ Version
3.24.41, cairo version 1.18.0)
Windowing system distributor 'The X.Org Foundation', version 11.0.12101011
System Description: Guix System
Configured using:
'configure
CONFIG_SHELL=/gnu/store/fl3l5wx8qynjrvx5lilz6c38hb77cf36-bash-minimal-5.1.16/bin/bash
SHELL=/gnu/store/fl3l5wx8qynjrvx5lilz6c38hb77cf36-bash-minimal-5.1.16/bin/bash
--prefix=/gnu/store/45nwc8hc8fn1fhvr9qw01ylkfpvzxwsw-emacs-next-30.0.60-1.4e22ef8
--enable-fast-install --with-cairo --with-modules
--with-native-compilation=aot --disable-build-details'
0001-Keep-project-s-exec-path-during-with-temp-buffer-cal.patch
Description: Text Data
--- End Message ---
--- Begin Message ---
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Subject: |
Re: bug#72849: [PATCH] Keep project's exec-path during with-temp-buffer call |
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Date: |
Sat, 31 Aug 2024 13:17:58 +0300 |
> Date: Fri, 30 Aug 2024 23:43:57 +0900
> From: kobarity <kobarity@gmail.com>
> Cc: 72849@debbugs.gnu.org
>
> Evgenii Klimov wrote:
> > Eli Zaretskii <eliz@gnu.org> writes:
> >
> > >> Date: Wed, 28 Aug 2024 00:13:25 +0100
> > >> From: Evgenii Klimov via "Bug reports for GNU Emacs,
> > >> the Swiss army knife of text editors" <bug-gnu-emacs@gnu.org>
> > >>
> > >> `with-temp-buffer' doesn't respect buffer-local environment variables,
> > >> `exec-path' in this case. Which results in executables not being found,
> > >> or the wrong versions of executables being picked up. E.g. if
> > >> environment variable is modified via .dir-local file or direnv/envrc
> > >> package.
> > >
> > > Hmm, this doesn't look clean to me: exec-path is just one variable,
> > > what makes it special here?
> > >
> > > Moreover, it sounds like python-shell-with-environment, which
> > > python-shell-prompt-detect calls, already attempts to have
> > > buffer-local value of exec-path to be available to Python, so why
> > > isn't that working for you? And if it isn't work, I think we should
> > > amend python-shell-with-environment to do this, so we don't need to do
> > > it "by hand".
> >
> > Indeed, my initial approach is too manual.
> >
> > Here the problem that I have: I don't use Python's "venv" module to
> > create virtual environment for the project. Instead, I use GNU Guix's
> > "guix shell" command [1] which provides augmented PATH and PYTHONPATH,
> > etc. to link project's dependencies. Then, envrc.el package picks up
> > these environment variables and makes them buffer-local project-wise
> > (`exec-path' and `process-environment').
> >
> > You are correct that `python-shell-with-environment' provides
> > buffer-local variables, but `with-temp-buffer' treats `exec-path' and
> > `process-environment' variables very specially.
> >
> > I didn't find this behavior in documentation, but look at this example:
> >
> > (setq-default exec-path (list "global" "list"))
> > (setq-local exec-path (cons "local"
> > (default-value 'exec-path)))
> > (setq-default myvar (list "global" "list"))
> > (setq-local myvar (cons "local" (default-value 'myvar)))
> >
> > (let ((exec-path exec-path) ; takes buffer-local
> > (myvar myvar)) ; takes buffer-local
> > (with-temp-buffer
> > (insert (car exec-path) ; uses global
> > "\n"
> > (car myvar)) ; uses `let'-binded
> > (buffer-string)))
> > ;; => "global
> > ;; local"
> >
> > (require 'cl-lib)
> > (let ((myvar myvar))
> > ;; temporarily binds buffer-local value to global symbol
> > (cl-letf (((default-value 'exec-path) exec-path))
> > (with-temp-buffer
> > ;; global variable is used, but it's value is temporarily equal
> > ;; to buffer-local value
> > (insert (car exec-path)
> > "\n"
> > (car myvar))
> > (buffer-string))))
> > ;; => "local
> > ;; local"
> >
> > It's a simplified and expanded version of
> > `python-shell-with-environment' and `python-shell-prompt-detect'. As
> > you can see, `exec-path' is treated differently inside of
> > `with-temp-buffer' and `cl-letf' is needed to force `with-temp-buffer'
> > to use buffer-local value of `exec-path'.
> >
> > In the new patch attached I show how this can be overcome. Don't know
> > if you'll consider my use case too narrow and specific, but I'll be glad
> > to hear your thoughts on this.
> >
> > [1] https://guix.gnu.org/en/manual/en/guix.html#Invoking-guix-environment
>
> Thank you for your explanation and the new patch. It helped me to
> understand the problem correctly. I also confirmed that the new patch
> resolves the issue. I don't think it's a special use case, as I
> sometimes set `exec-path' locally using .dir-locals.el. I agree with
> the new patch.
Thanks to both of you. I've now installed this on the emacs-30
release branch, and I'm therefore closing this bug.
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