https://gcc.gnu.org/bugzilla/show_bug.cgi?id=97865
--- Comment #6 from Jürgen Reuter <juergen.reuter at desy dot de> --- (In reply to Iain Sandoe from comment #5) > I bootstrapped several times (without using MACOSX_DEPLOYMENT_TARGET) and > have been looking into other issues. > > Note that the libgfortran directory throws up a lot of warnings when > 'autoreconf'ed' so maybe there's some things to be looked at there anyway. Ok, sorry, my reply was not so clear (even to me): I also never used MACOSX_DEPLOYMENT_TARGET myself. The main point in my fix is that libtool defaults to 10.0 for the TARGET, and then the second option matches, not the first one because now there is not darwin1x.x anymore, but darwin20. In any case, it looks like that Fortran code that either uses bind(C) to C++ libraries or legacy Fortran code based on common blocks produces ubiquitous SIGABRT when compiled with -Wl,-flat_namespace and without -Wl,-dynamic_lookup.