Read-only /usr/obj/ no longer kosher?

[Garrett Cooper]

> On Aug 26, 2015, at 19:03, O'Connor, Daniel <darius at dons.net.au> wrote:
> 
> 
>> On 27 Aug 2015, at 08:25, Pawel Jakub Dawidek <pjd at freebsd.org> wrote:
>>> On Tue, Aug 25, 2015 at 03:32:35PM -0700, NGie Cooper wrote:
>>>> On Tue, Aug 25, 2015 at 3:21 PM, Xin Li <delphij at delphij.net> wrote:
>>>> On 08/25/15 14:55, Pawel Jakub Dawidek wrote:
>>>>>> Now that I think of it, it might have been that I did
>>>>>> buildworld/buildkernel before -p1. Then freebsd-update updated
>>>>>> newvers.sh and then I was trying to do installworld.
>>>>> 
>>>>> Yes, I can now reproduce it with source updated to -p2.
>>>> 
>>>> Yes, that's because freebsd-version.sh is generated from the files (but
>>>> it's not clear to me whether if it's a bug or a feature that 'make
>>>> install' checks if it's up-to-date and decides to regenerate it...).
>>> 
>>> It's a quirk for sure. If you change the behavior, people will
>>> definitely complain as they will now need to go back and rebuild
>>> everything.
>> 
>> What we have now is misleading. People should recompile. It is rather
>> rare to see security advisory which bumps only patch level and something
>> that doesn't require recompilation (eg. a shell script). Current
>> behaviour would make people think they are running latest patch level
>> because freebsd-version says so, eventhough they only did 'make
>> installworld' without rebuilding affected binaries.
> 
> So..
> How hard would it be to force CC/CXX to /usr/bin/false during installworld?

Trivial in FreeBSD. Just make it so in Makefile for the installworld target, add false to itools, and add appropriate special casing in bsd.compiler.mk.

Doing this just prevents recompiling though, so not pjd's case.

Also, this might break someone's random usecase where they need CC/CXX to do something meaningful at install time, however, the likelihood of it being correct is slim IMHO..