If an older program version (no longer shipped in Debian) segfaults with an updated version of a library package (with the same SONAME, etc.), but continues to work fine with an older version of that library, is that considered a bug in the new version of the library package?
I have a case of that happening, with a program that matters quite a lot to me, and I'm trying to assess whether it would be potentially worth the trouble for me to report the segfault as a bug against the library package involved, vs. focusing my effort on trying to find ways to work around the problem. That's partly a matter of principle (if libraries break backward compatibility, shouldn't they have to change SONAME or similar?), partly a matter of maintainer opinions/attitudes (how open is the maintainer to problems with applications and versions not shipped in Debian?), and partly a matter of how practical it would or wouldn't be to get it fixed (with no debug symbols in the program, there might not be any useful way to diagnose the problem, even if it *is* with the library proper). The library at hand is libfontconfig1. The program at hand (which I still run as an older version intentionally) is Icedove, Debian's former rebranded variant of Mozilla Thunderbird. The question being asked is *NOT* about Icedove/Thunderbird or libfontconfig1 specifically, however; it is about the more general considerations outlined above. I recently had to restart my computer due to a power outage. After the boot-up, Icedove involved failed to launch. Running it from a terminal showed that it segfaults. Running it under gdb showed that the segfault is inside a function call from libfontconfig1; as this build of Icedove does not have debug information available, I don't have any ready way to take it any further than that (although see below). That was with libfontconfig1 installed at version 2.17.1-3, from current testing. With some difficulty (because of version-match requirements among various other library packages), I downgraded libfontconfig1 to version 2.15.0-2.3 (from current stable); after that, the program again launched without issues. I can very probably reproduce the issue on demand by upgrading the library packages again, but I am hesitant to do so without a specific intention in mind, because downgrading again could be a pain (and if I don't successfully downgrade, I lose E-mail access until such time as I can find a solution by other means). ...While writing the above it occurred to me that if I install the -dbgsym package for libfontconfig1 (and any other library packages that turn out to be in the call chain), I might be able to get a more useful stack trace out of gdb. If I do get to the point of reproducing the issue, that may very well be worth the attempt. -- The Wanderer The reasonable man adapts himself to the world; the unreasonable one persists in trying to adapt the world to himself. Therefore all progress depends on the unreasonable man. -- George Bernard Shaw
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