Better way to do conditional inclusion in make

[Simon J. Gerraty]

NGie Cooper <yaneurabeya at gmail.com> wrote:
> > how does it cope with the case where a single file is dependent on either of
> > two options.
> > (we have this in our tree.. not sure if it occurs in the FreeBSD tree.)
> > file could occur in both lists or twice in one list..
> 
> This is a good, valid point. I think that Warner's proposal will fix
> the simple case (using one knob), but not the more complex case.

FILES:= ${FILES:O:u}

should cover that case.

> What concerns me about the short description of the implementation,
> (and something that I'm going to add to the phabricator review) is
> that this will:
> 
> 1. Break using FILESGROUPS

Why?

> 2. Requires creating snippets for dealing with magic in bsd.*.mk (I
> wouldn't want this magic going into the general purpose snippets
> because it would probably break backwards compatibility).

Not necessarily eg. if you clean/simplify the list after building it.