bug#72849: [PATCH] Keep project's exec-path during with-temp-buffer call

[Eli Zaretskii <eliz@gnu.org>]

> Date: Fri, 30 Aug 2024 01:08:25 +0900
> From: kobarity <kobarity@gmail.com>
> Cc: 72849@debbugs.gnu.org
> 
> Eli Zaretskii wrote:
> > > 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".
> > 
> > kobarity, any comments or suggestions?
> 
> The problem is that `with-temp-buffer' creates a new buffer, so the
> buffer local value of `exec-path' is not maintained in the new buffer.
> It is used to find the Python interpreter unless the interpreter is
> specified using the absolute path.
> 
> I think Evgenii's patch is logically correct, but it would be better
> to create a modified version of `with-temp-buffer' which keeps
> `exec-path' in the new buffer.  The attached is my proposal to do so.

Thanks, but what about python-shell-with-environment: doesn't it
already try to do this, including preserving exec-path from the
original buffer?