Bug#797718: flann: transition may be needed for g++-5 ABIs

[Gilles Filippini]

On Mon, 07 Sep 2015 08:44:46 +0200 Gilles Filippini <pini at debian.org> wrote:
> Control: unblock -1 by 791067
> 
> On Tue, 1 Sep 2015 23:02:18 +0100 Simon McVittie <smcv at debian.org> wrote:
> > Source: flann
> > Version: 1.8.4-4.1
> > Severity: important
> > Control: block -1 by 791067
> > 
> > Background[1]: libstdc++6 introduces a new ABI to conform to the
> > C++11 standard, but keeps the old ABI to not break existing binaries.
> > Packages which are built with g++-5 from experimental (not the one
> > from testing/unstable) are using the new ABI.  Libraries built from
> > this source package export some of the new __cxx11 or B5cxx11 symbols,
> > dropping other symbols.  If these symbols are part of the API of
> > the library, then this rebuild with g++-5 will trigger a transition
> > for the library.
> > 
> > In the case of flann, std::string appears in header files that
> > get installed, but it seems possible that all instances are inline
> > (and hence do not affect the ABI). Someone who knows more C++ than me,
> > such as the maintainer, should check whether a transition is needed.
> > If in doubt, the safe option is to do the transition anyway (see
> > <https://lists.debian.org/debian-release/2015/08/msg00574.html>
> > for justification).

I've rebuilt flann locally with a .symbols file and it appears that
libflann1.8 does export cxx11 symbols.

> > 
> > The transition consists of renaming the affected library packages, adding a
> > v5 suffix (libflann1.8v5). The SONAME should not be changed.
> > 
> > These follow-up transitions for libstdc++ are not going through exactly
> > the normal transition procedure, because many entangled transitions are
> > going on at the same time, and the usual ordered transition procedure
> > does not scale that far. When all the C++ libraries on which this library
> > depends have started their transitions in unstable if required, this
> > library should do the same, closing this bug; the release team will deal
> > with binNMUs as needed.
> > 
> > In the case of flann, if a transition is needed, it looks as though it
> > will be necessary to wait for hdf5 (#791067).

The good news is that libflann1.8 doesn't have any reverse dependency. 4
packages (fcl, hugin, ompl, pcl) build-depends on libflann-dev but none
of the resulting binary packages actually depends on libflann1.8.

Then a binnmu for flann should suffice.

> No, it doesn't depend on the C++ API of HDF5.

Thanks,

_g.

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