20 juli 2019 kl. 20.50 skrev Basil L. Contovounesios <contovob@tcd.ie>:
> 
> New user options in central places like files.el (as opposed to some
> specialised package) usually warrant a RFC so as to establish which need
> they are addressing, whether this need masks some other issue, and
> whether the proposed change covers this need sufficiently well.
> 
> Internal variables can come and go, but user options are user-facing
> contracts that are harder to change or get rid of.

Agreed, and this defcustom (file-size-function) has a much more general-sounding name and description than merited by its effects (which are limited to the "available disk space" number in Dired and that's it).

Attached is a minimal clean-up which remedies some of the flaws, but perhaps we should instead roll back the defcustom and all related changes entirely until a cohesive proposal is forthcoming, as per your and Eli's comments. Fighting it out in the source isn't really going to be productive.