[buildd-tools-devel] Bug#810871: Bug#810871: Bug#810871: [sbuild] Please provide a way to set an environment variable to the build directory

[Ian Campbell]

On Thu, 2016-01-14 at 08:38 +0100, Johannes Schauer wrote:
> Hi,
> 
> Quoting Katsuhiko Nishimra (2016-01-14 04:53:37)
> > On Thu, 14 Jan 2016 00:37:19 +0100 Johannes Schauer <josch at debian.org> wrote:
> > > 
> > > Is this documentation not working for you:
> > > 
> > > https://wiki.debian.org/sbuild#Using_.22ccache.22_with_sbuild
> > 
> > Yes, I've followed the instructions above and encountered cache misses.
> 
> I would like to understand why this fails now so I CC-ed Ian Campbell who seems
> to be responsible for the last big overhaul of that section in the wiki.
> 
> sbuild has been choosing a randomized build path for a long time so I don't
> know why it apparently doesn't work anymore all of a sudden.
> 
> Maybe something changed in more recent ccache versions?

FWIW I just tried with a non-cmake package (sunxi-tools) and I'm
getting the expected cache hits. My config is like the wiki.

Trying with xss-lock (which uses cmake) I do get cache misses unless I
use --build-path too.

I had a look at the ccache (upstream and Debian) changelog since the
Jessie version and there's no obvious mention of a deliberate change,
but it may be an as yet undiscovered bug.

Or (more likely IMHO) maybe while it worked generally it hasn't worked
with cmake and noone noticed. If not all your projects use cmake it
might be quite subtle unless you explicitly went looking since the
numbers would tend to increase anyway.

http://stackoverflow.com/questions/2008642/ccache-and-absolute-path
seems to suggest that at least one other person (or group of people) have noticed this interaction between cmake and ccache (without sbuild being involve AFAICT).

Ian.