https://gcc.gnu.org/bugzilla/show_bug.cgi?id=77327
--- Comment #8 from Vittorio Zecca <zeccav at gmail dot com> --- Yes, it seems to me that import4.f90 is sufficient to trigger the asan memory checker. How strange, even without "implicit none" the loader should have complained that "sub2" was referenced but undefined. This is how I find the bug. It is not that trivial to build a sanitized version of gcc/g++/gfortran but nonetheless it is possible. Once you have a sanitized gfortran and f951 then you can check it against the gcc testsuite Fortran files, as I did.