Subject: Re: bug#70408: 30.0.50; Eglot and Project integration

From: João Távora <[email-masked]>
Date: Tue, 16 Apr 2024 14:51:10 +0100

On Tue, Apr 16, 2024 at 1:56 PM Dmitry Gutov <[email-masked]> wrote:

> IIUC Ergus's request is primarily about a situation where an
> "out-of-tree" build is used. Meaning, the directory for build artefacts
> is not a subdirectory of the project root, but -- apparently -- some
> sibling directory of it (e.g. "../build"). So it's somewhat atypical,
> although I suppose the solution from the link above might work with it too.

Ah, I know about that.  That's where compile-commands.json is generated
by CMake.  But using that './build' as the project root passed via LSP
to clangd
(and likely any other server) will most likely fail: that's not  the
project root
and it doesn't have any versioned source files  (only auto-generated ones).

Because of this, C++ projects usually have sth like:

  ln -sf build/compile_commands.json compile_commands.json

as a build step.

Alternatively, you invoke clangd with `--compile-commands-dir=build`.
I don't think there's anything project.el or Eglot can do or should do
about this case.

> This bug is split off from an emacs-devel discussion, where I posted a
> draft solution of mine:
> https://lists.gnu.org/archive/html/emacs-devel/2024-04/msg00279.html
> I'm curious for any feedback - like would that be good enough for this
> and related cases, or maybe if someone has an even simpler approach in mind.

I'll pass, but wish you luck.  I've stated in the past that I think
project.el should
allow subprojects inside larger projects, and let users of
project-current (direct
or indirect) specify if they're interesting in the innermost,
outermost, or intermediate
projects when searching for projects to act on, via a combination of prefix
arguments, arguments, customized special variables or let-bound special
variables.

João