On Thu, Jan 26, 2012 at 08:58:55AM +0100, Raphael Hertzog wrote: > Hi, > > On Wed, 25 Jan 2012, Russ Allbery wrote: > > 4. Once I had a symbols file that resulted in a successful build and that > > I could have uploaded, I started thinking about how I was going to > > maintain it. With a C program, I would change the symbols file > > versions when the underlying function implementation changes in a way > > that may not offer eqiuvalence, similar to bumping shlibs. I realized > > that I was going to have no idea when that happened, and the only way > > that I would maintain the symbols file would be to either trust > > upstream to maintain ABI equivalence and therefore only change the > > symbols file when upstream changes the SONAME, or not trust upstream to > > maintain ABI equivalence and therefore change all the versions with > > each new upstream release. That gives me exactly the same semantics as > > a shlibs file, so what's the point in having a symbols file? > > The main benefit of the symbols file is that new symbols (API extension) > are listed with the version where they have been introduced. So that > seriously reduces the number of packages which would be affected by the > equivalent shlibs bump. > > Otherwise I agree with you, maintainers of C++ libs are unlikely to be > able to (preemptively) detect when a given symbol should have had its > version bumped... so you should really trust upstream and hope to catch > API extension that preserve ABI in the upstream changelog. > > > 5. The exported symbols of the library contained many symbols that > > obviously weren't really from that library, but instead were artifacts > > of the C++ compilation process, things like instantiations of > > std::vector. Do those go into the symbols file? Do they change from > > architecture to architecture? If they disappear again, is that > > actually an ABI break? How do I know? It's all very mysterious, and > > while shlibs provides the same semantics as just ignoring this, at > > least I'm not then including in the package data, generated by me, > > things that I'm just blindly ignoring. > > It's also very mysterious to me. :) But Modestas Vainius has still managed > to maintain symbols files for many KDE libraries. He might be able to tell > you more.
Chances are KDE libraries are using visibility flags when compiling, which limits the number of exported symbols. Mike -- To UNSUBSCRIBE, email to debian-devel-requ...@lists.debian.org with a subject of "unsubscribe". Trouble? Contact listmas...@lists.debian.org Archive: http://lists.debian.org/20120126080540.ga23...@glandium.org
