https://gcc.gnu.org/bugzilla/show_bug.cgi?id=81986
--- Comment #2 from Vittorio Zecca <zeccav at gmail dot com> --- I do not know if this is a libgfortran or a sanitizer bug. What I do know is that changing string.c:199 from t = - n; into t = -(GFC_UINTEGER_LARGEST)n; as it should be, the sanitizer message disappears and the whole original test case pr66311.f90 runs smoothly.