[PATCH] Project out of sources compilation

[Ergus]

Hi:

Here I attach a very simple patch to allow project out of sources
compilation and project build detection.

So far I already implemented a very primitive backend [1] for project.el
using these features to detect and compile autotools and cmake projects;
and, at some point I will propose it for elpa.

But I need to work a bit more on it; and, of course, the functionalities
in the attached patch need to go to vanilla this way or some other
equivalent.

Best,
Ergus

[1] 
https://github.com/Ergus/project-multi-mode/blob/master/project-multi-mode.el



On Tue, Mar 19, 2024 at 07:36:35PM +0100, Ergus wrote:
> Hi Dmitry:
>
> Here I attach a very simple approach to add support for out of sources
> compilation in project.el
>
> This is just a POC, but to have some starting point to discuss.
>
> Best,
> Ergus
>
>
>
> On Sun, Mar 17, 2024 at 06:47:43PM +0100, Ergus wrote:
> > On Sun, Mar 17, 2024 at 12:36:44PM +0100, Augusto Stoffel wrote:
> > > On Sat, 16 Mar 2024 at 14:12, Ergus wrote:
> > >
> > > > 5. Project local variables (a man can dream, a man can dream)
> > > >
> > > > There are some situations where we want to have variables shared among a
> > > > project. (i.e some output directory, logging option when executing,
> > > > flags, environment variables).
> > > >
> > > > At the moment these options work partially by using directory
> > > > variables. If we have the concept of a "project", maybe it is logical to
> > > > have some sort of project scope concept, specially for projects sharing
> > > > a common root.
> > >
> > > For Emacs variables, why you think dir-local variables only works
> > > “partially”?
> > >
> > > As to environment variables, they are generally assumed to be global in
> > > Emacs and it goes a bit against the grain to make them buffer-local /
> > > project dependent.  Nonetheless, there are packages for that (one is
> > > buffer-env, which I wrote) and they work fine (at least for me).
> > They work for one directory, but when the project includes multiple
> > roots (project-external-roots) the variables are somehow missing just
> > when jumping with xref to a definition.
> >
> > However, we can ignore this as I mentioned before.
> >
> > > > For example vs-code adds a subdirectory with project variables that the
> > > > user (but also any plugin) can refer to in the project's scope.
> > >
> > > Is this meant to store editor configuration or environment variables?  I
> > > guess turning VSCode configuration variables into Emacs alternatives
> > > would be tricky.
> >
> > No please. No interaction-importing from other editors will be
> > maintainable in the long path.
> >
> > > But if this is about env vars and the directory
> > > organization is sensible, then one could configure buffer-env to
> > > interoperate.
> >
> > This is it. The idea is to extend project.el in order to bring more
> > project-oriented features.
> >
> > Lets say:
> >
> > The user (or project.el backend) could specify the `build` directory and
> > the environment that needs to be set to execute the program from the
> > build or bin directory.
> >
> > So with a simple modification of dir-locals.el the user may be capable
> > to run M-x compile (or project-compile), M-x gud-gdb... or being more
> > ambitious M-x project-generate (to call autogen.sh and ./configure or
> > cmake depending of the project-backend)
> >
> > For sure we wont cover the 100% of the projects, but wuth automake and
> > autotools we will be very close (and in the future someone could add
> > other backends for it)

> commit cfa10dfeac01ae25a7acd6857fae0b377b625779
> Author: Jimmy Aguilar Mena <kratsbinovish@gmail.com>
> Date:   Tue Mar 19 17:57:25 2024 +0100
>
>    Add basic project-build-dir implementation
>
>    This is just a dummy prototype to discuss about alternatives.
>
> diff --git a/lisp/progmodes/project.el b/lisp/progmodes/project.el
> index ac18aceadcf..0ca4ca85566 100644
> --- a/lisp/progmodes/project.el
> +++ b/lisp/progmodes/project.el
> @@ -51,6 +51,9 @@
> ;; files inside the root must not be considered a part of it).  It
> ;; should be consistent with `project-files'.
> ;;
> +;; `project-build-dir' can be overridden if the project backend has some
> +;; extra information about the project build directory.
> +;;
> ;; This list can change in future versions.
> ;;
> ;; Transient project:
> @@ -208,6 +211,12 @@ project-prompter
>   :group 'project
>   :version "30.1")
>
> +(defcustom project-build-dir nil
> +  "Build directory for current project."
> +  :type 'directory
> +  :safe t
> +  :version "30.1")
> +
> ;;;###autoload
> (defun project-current (&optional maybe-prompt directory)
>   "Return the project instance in DIRECTORY, defaulting to `default-directory'.
> @@ -289,8 +298,30 @@ project-external-roots
> headers search path, load path, class path, and so on."
>   nil)
>
> +(cl-defgeneric project-build-dir (_project)
> +  "Return build directory of the current PROJECT.
> +
> +This function is intended to be defined by the backend when possible.
> +Otherwise this returns nil and the `project-compile' command will be
> +called in the project-root.
> +If the user defines the directory-local variable `project-build-dir' it
> +will have precedence over the result of this function."
> + nil)
> +
> +(defun project-get-build-dir (project)
> +  "Return build directory of the current PROJECT.
> +If the variable `project-build-dir' is defined, this function returns
> +it, otherwise it returns the project root.  If the defined path is
> +relative, this expands it relatively to the project's root"
> +  (let ((dir (or project-build-dir
> +                 (project-build-dir project)
> +                 (project-root project)))) ;; I assume project-root is absolute
> +    (if (file-name-absolute-p dir)
> +        dir
> +      (expand-file-name dir (project-root project)))))
> +
> (cl-defgeneric project-name (project)
> -  "A human-readable name for the project.
> +  "A human-readable name for the PROJECT.
> Nominally unique, but not enforced."
>   (file-name-nondirectory (directory-file-name (project-root project))))
>
> @@ -1391,7 +1422,7 @@ project-compile
>   "Run `compile' in the project root."
>   (declare (interactive-only compile))
>   (interactive)
> -  (let ((default-directory (project-root (project-current t)))
> +  (let ((default-directory (project-get-build-dir (project-current t)))
>         (compilation-buffer-name-function
>          (or project-compilation-buffer-name-function
>              compilation-buffer-name-function)))

project-compile.patch
Description: Text document