Summary:
Clang -fpic defaults to -fno-semantic-interposition (GCC -fpic defaults
to -fsemantic-interposition).
Users need to specify -fsemantic-interposition to get semantic
interposition behavior.
Semantic interposition is currently a best-effort feature. There may
still be some cases where it is not handled well.
Reviewers: peter.smith, rnk, serge-sans-paille, sfertile, jfb, jdoerfert
Subscribers: dschuff, jyknight, dylanmckay, nemanjai, jvesely, kbarton, fedor.sergeev, asb, rbar, johnrusso, simoncook, sabuasal, niosHD, jrtc27, zzheng, edward-jones, atanasyan, rogfer01, MartinMosbeck, brucehoult, the_o, arphaman, PkmX, jocewei, jsji, Jim, lenary, s.egerton, pzheng, sameer.abuasal, apazos, luismarques, cfe-commits
Tags: #clang
Differential Revision: https://reviews.llvm.org/D73865
It turns out there are some sort-of-but-not-quite empty structs that break all
the rules. For example:
struct SuperEmpty { int arr[0]; };
struct SortOfEmpty { struct SuperEmpty e; };
Both of these have sizeof == 0, even in C++ mode, for GCC compatibility. The
first one also doesn't occupy a register when passed by value in GNU C++ mode,
unlike everything else.
On Darwin, we want to ignore the lot (and especially don't want to try to use
an i0 as we were).
llvm-svn: 302313