bug#59868: 28.2.50; compilation-search-path incompatible with dir-locals

[Eli Zaretskii <eliz@gnu.org>]

> From: Len Trigg <lenbok@gmail.com>
> Date: Sat, 10 Dec 2022 08:11:10 +1300
> Cc: 59868@debbugs.gnu.org
> 
>  You are ignoring the first sentence in my response, right?
> 
>  I don't think so - the purpose of my email was essentially to ask why you thought the variable shouldn't be
> buffer-local in *compilation* buffers.

Because from the pattern we use the *compilation* buffer it is clear
that it cannot be buffer-local.  The *compilation* buffer is reused by
each new compilation, so local setting there makes no sense.

> In my specific case the project is in R (which is a terrible language for software development) and we are
> using a single top level makefile in the project. It has a target to run linting, which (within each R linter
> invocation) lints from a subdirectory, and the filenames in each lint message are relative to those
> directories. There is not the hierarchy of makefiles that you would often see in say C projects, where
> compilation mode could parse make-issued messages about changing directories etc. It seemed a perfect
> fit for compilation-search-path. I am currently working around it with the following ugliness in my
> .dir-locals.el:

Why cannot you have all the possible directories in the list?