Hi Pierre, On Tue, Jul 11, 2023 at 04:10:49PM +0200, Pierre Gruet wrote: > Dear Mentors, > > I maintain a package that builds a shared library. I uploaded a new upstream > version of it to Debian, with no removed symbols, no ABI change... Fine.
> Unfortunately, it turns out fields were added to some class (of which size > thus increased) in the shared library, so that binaries built against a > previous version of it now segfault as they are not allocating enough space. > > Of course, rebuilding the reverse dependencies fixes the segfaults. > How should we handle such situation in Debian? Quoting Policy 8.1: > > The SONAME and binary package name need not, and indeed normally > should not, change if new interfaces are added but none are removed or > changed, since this will not break binaries linked against the old > shared library. Correct versioning of dependencies on the newer shared > library by binaries that use the new interfaces is handled via the > symbols or shlibs system. > > So my understanding is that no SONAME change and no transition are needed, > although the rdeps indeed have to be rebuilt as their binaries _are_ broken > by the new version of the library. In short: ABI change is not limited to removing symbols. Your library broke ABI by adding members, and would have required a SONAME bump. There is some guide what you can and cannot do in terms of ABI: https://community.kde.org/Policies/Binary_Compatibility_Issues_With_C++ There is a tool to check for breakage: https://lvc.github.io/abi-compliance-checker/ (it is in Debian: https://tracker.debian.org/pkg/abi-compliance-checker) -- Cheers, tobi
