[Bug sanitizer/87880] [9 regression] All macOS asan execution tests FAIL

[iains at gcc dot gnu.org]

https://gcc.gnu.org/bugzilla/show_bug.cgi?id=87880

--- Comment #6 from Iain Sandoe <iains at gcc dot gnu.org> ---
so I looked a little more at this.

As Rainer points out, the libsupc++ implementation does not provide
cxa_rethrow_primary_exception whereas the libc++-abi.dylib has it.

For the macOS implementations of libstdc.6.dylib and libc++.dylib the symbols
from libc++-abi are forwarded via the presented library.  For the GCC
implementation of libstdc++.dylib, the libsupc++ implementation is statically
linked into the library.

So - it seems that the build for libsanitiser is either resolving those symbols
accidentally from the /usr/lib/libstdc++.dylib (or has been constructed to
permit them to be unresolved at link time)

 - first case seems a build bug
 - second case they should be guarded by a check for presence at runtime (IIRC
there are already an number of symbols that are guarded this way).

Longer term:
1. we could add the cxa_rethrow_primary_exception to libsupc++ (will talk to
Jonathan about the implications of this)

2. We could split libstdc++ from libsupc++ on Darwin and have the option to
build the library on top of libc++abi (forwarding the symbols as the installed
system library does).

 - this is analogous to the need to forward to the unwinder implementation
which must always be provided by the shared /usr/lib/system impl on Darwin.

It's not 100% clear at the moment if there's state in the abi lib that would
mandate that action anyway.

At the Cauldron I talked to Jonathan about potentially doing this split, and he
didn't at that point have any objection.