[bug#28185] [PATCH] build: emacs-build-system: Make the install phase more helpful.

[Arun Isaac]

Christopher Baines writes:

> Modify the install phase to detect when nothing has been installed, and error
> if this happens. This is preferable to continuing, and allowing the next phase
> to fail.
>
> Also, when nothing can be found to be installed, print out each file that was
> considered, along with the regular expressions that were used to include and
> exclude it.
>
> * gnu/build/emacs-build-system.scm (install-file?): Add additional error
>   checking and logging.
> ---
>  guix/build/emacs-build-system.scm | 45 
> ++++++++++++++++++++++++++++-----------
>  1 file changed, 32 insertions(+), 13 deletions(-)

I feel that this adds a lot of complexity (lines of code) to the
emacs-build-system checking for an error that can be quite easily
identified and fixed otherwise.

WDYT? Maybe, others can comment on this as well.