ar and ranlib -D

[Warner Losh]

On Apr 10, 2014, at 9:22 AM, Ed Maste <emaste at freebsd.org> wrote:

> On 10 April 2014 11:06, Dag-Erling Smørgrav <des at des.no> wrote:
>> The attached patch adds -D to ARFLAGS and introduces RANLIBFLAGS which
>> defaults to -D.  This ensures that all timestamps inside static
>> libraries in the base system are hardcoded to 0 (aka the epoch), which
>> is a huge step towards fully reproducible builds.  Any objections?
> 
> Looks good to me, I'm not sure why this didn't happen long ago.

Once upon a time, ranlib didn’t like this too well and complained that
the index was older than the file. Then it was made a special case. These
days (and these days includes time since ~1995 or 2000), people
always rebuild the entire .a anyway, so the value of having a timestamp
in there is low, at best, so always doing this has become so boring
that i’m surprised this isn’t the default behavior. Given that we always
rebuild, though, this change is totally safe.

Warner