Source: quantlib
Version: 1.6.2-1
Severity: serious
Justification: ABI break since stable for libquantlib0
Tags: sid stretch
User: debian-...@lists.debian.org
Usertags: libstdc++-cxx11
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 quantlib, <ql/currency.hpp> is one example of public API
changing its ABI in this way, so a transition does appear to
be needed. The transition normally consists of renaming the affected library
packages, adding a v5 suffix (libquantlib0v5). The SONAME should not be
changed when doing this.
If an upgrade to a new upstream SONAME is already planned, and that
SONAME has never been available in Debian compiled with g++-4, then an
alternative way to carry out the transition would be to bump the
SONAME. However, the libstdc++ transition has been going on for nearly
2 months already, and anything that makes it take longer is bad for Debian,
so introducing new upstream code is not recommended at this stage.
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.
Looking at the build-dependencies of quantlib, boost has already had
its transition, so I believe quantlib is now ready to be renamed.
quantlib does appear to have had an upload built with g++-5 already.
Please note that this rebuild is *not* sufficient to prevent broken
upgrades: for example, during an upgrade from jessie to stretch, if a
user upgrades quantlib to the stretch version while keeping jessie's
quantlib-swig or rquantlib, then quantlib-swig or rquantlib will
fail to link at runtime with undefined symbols. Preventing broken
situations like that is why the renames are necessary.
The package might be NMU'd if there is no maintainer response. The
release team have declared a 2 day NMU delay[2] for packages involved
in the libstdc++ transition, in order to get unstable back to a usable
state in a finite time.
Regards,
S
[1] https://wiki.debian.org/GCC5#libstdc.2B-.2B-_ABI_transition
[2] https://lists.debian.org/debian-devel-announce/2015/08/msg00000.html
