Installworld and /usr/include/*.h modification times

[Kimmo Paasiala]

On Fri, Jun 1, 2012 at 8:45 PM, Lowell Gilbert
<freebsd-stable-local at be-well.ilk.org> wrote:
> Kimmo Paasiala <kpaasial at gmail.com> writes:
>
>> Why are /usr/include files installed with "install -C" during "make
>> installworld"  when almost everything else is installed without the -C
>> flag? This makes it harder to track which files were actually
>> installed during the last "make installworld". One can easily find
>> obsolete files  (that are not covered with make delete-old(-libs))
>> with "find -x / -type f -mtime +suitable_time" but this doesn't work
>> for /usr/include files because the modification times are not bumped
>> on "make installworld".
>
> "make" uses timestamps to determine whether to trigger a rule. Changing
> timestamps on source files without changing the contents is a bad idea.

Yes, I'm aware of how make uses timestamps for figuring out out of
date targets. However I would argue that after updating world with
"make installworld" (which is done in single user mode there for
requiring at least one reboot) you should start any compilations from
scratch. The ports system does this by default and cleans up any
previous work files before new compilation. I just don't see where
bumping of mtimes for those files would have that great impact, does
anyone?