Re: Project out of sources compilation

[Ergus <spacibba@aol.com>]

On Sun, Mar 17, 2024 at 07:38:16PM +0200, Eli Zaretskii wrote:
>> Date: Sun, 17 Mar 2024 18:33:21 +0100
>> From: Ergus <spacibba@aol.com>
>> Cc: dmitry@gutov.dev, emacs-devel@gnu.org
>>
>> >Maybe I'm missing something, but isn't the build tree just one more
>> >tree that is part of the project?  If so, can't you use
>> >project-external-roots to add this tree to the project?  I thought
>> >this was the mechanism to add trees to a project as included in the
>> >original design of project.el and its support in Emacs?
>> >
>>
>> >> There is also some need for a 'bin' dir, that is, where the final executable will reside, useful to execute and debug with tools like gud and independent from 'build'...  For example in a python project this may be the project root OR where the file with __main__ resides, but a python project usually won't specify a build dir. But let's go for one thing at a time.
>> >
>> >Likewise here.
>> >
>> >Or what am I missing?
>>
>> Hi Eli:
>>
>> More or less we have it, that's why I said that there was just some
>> (small) missing pieces.
>>
>> We have the `project-external-roots`, but project.el uses them only to
>> find files and regexps. So it looks like they are intended to be source
>> places somehow.
>>
>> The compile or debug programs doesn't know that they are intended to
>> execute there.
>>
>> However, a `build` or `bin` are different because they are where the
>> `compile` or `gud` are intended to run; generally not a place to search
>> for sources (unless the source is generated like config.h).
>
>Are you saying that "M-x compile" and "M-x gdb" are not (yet)
>supported by project.el?
>

Kind of. There is project-compile, but executes in the root
directory. And M-x compile does not have any custom to control the
execution place, so it needs to do a let around it.

something similar happen to gdb, or project-eshell.

So, what is not actually supported is out of sources
compilation/execution. In the first email I explained that part. Even
Eglot requires extra work to function properly.