[cfe-dev] [libc++] Implementation of std::map::erase() in libc++ doesn't match that in libstdc++

[Alexander Potapenko]

Hi all,

We've encountered an incompatibility between libc++ and libstdc++: for
std::map::erase(pos) libstdc++ (and MSVS as well) first removes the
item from a map (a) and then calls its destructor (b), while libc++
calls the destructor before changing the map structure.

This results in a crash described at
https://code.google.com/p/chromium/issues/detail?id=358707: the item
that's being erased from the map queries that map in the destructor
calls some methods for the elements it finds. With libc++ that item
manages to find itself (in an inconsistent state, since it's in the
destructor already) and crashes.

Does the standard specify the order of (a) and (b), or it's incorrect
to rely on the order provided by some of the libraries?

TIA,
Alexander Potapenko
Software Engineer
Google Moscow