Subject: Re: bug#48907: Grafts cause discrepancies in debug symbols file names (debug symbols missing in GDB).

From: Ludovic Courtès <[email-masked]>
Date: Fri, 24 Sep 2021 16:14:47 +0200

Hi,

Maxim Cournoyer <[email-masked]> skribis:

> Ludovic Courtès <[email-masked]> writes:

[...]

>> This is due to the fact that, when you run ‘guix build jami-qt’, the
>> grafting derivation dismisses the “debug” output of qtdeclarative, since
>> jami-qt does not depend on it.  That way it doesn’t have to
>> build/download and graft qtdeclarative:debug.

[...]

> Yikes!  This means that debugging with grafts (with the aid of debugging
> symbols) is no longer possible, right?

It depends on whether the separate “debug” output gets grafted or not,
but yeah, if a dependency tree has this shape (app -> lib + lib:debug),
running ‘guix install app’ alone will prevent you from getting debugging
symbols from ‘lib:debug’ I believe.  That sucks.

I wonder if we should revert 482fda2729c3e76999892cb8f9a0391a7bd37119.
It’s often not very helpful anyway (we often find ourselves downloading
unnecessary package outputs because of grafting).

> I remember reading about a 2nd option to locate the separate debug
> symbol files with GDB in info '(gdb) Separate Debug Files':
>
>
>    * The executable contains a "build ID", a unique bit string that is

We’d have to check if this is applicable.  Looking at the ld manual
(info "(ld) Options"), it seems that the UUID “style” is ruled out
because it’s non-deterministic, and the md5 and sha1 styles would
require us to rewrite build IDs IIUC, similar to how we rewrite CRCs.

Thanks,
Ludo’.