Re: reproducible builds and debugging information

[ludo@gnu.org (Ludovic Courtès)]

Tomáš Čech <sleep_walker@gnu.org> skribis:

> As I was tracing curl code, I needed to rebuild the package with
> "-ggdb" in CFLAGS and enable debug among outputs.
>
> The later doesn't change the hash (and the generated code), but the
> first does.

Both approaches change the output hash.  (As soon as a bit changes in
the build process, the output hash changes.)

Adding a “debug” output is nice because we have support to automatically
DTRT (info "(guix) Installing Debugging Files").

> So I'd like to propose to put "-ggdb" to generally applied CFLAGS for
> whole distribution.

Packages that have an autoconf-based build system, and I suppose most
others, are built with -g.  The binaries get stripped by default and
debugging info is lost unless the package has a “debug” output.

Currently a few key packages have that, but most don’t (I think Debian
does something similar, not sure about other distros.)

We could make it opt-out rather than opt-in, but the issue is disk usage
on build machine (including end-user machines.)  See
<http://lists.gnu.org/archive/html/bug-guix/2013-07/msg00015.html>.

Thoughts?

Ludo’.