https://gcc.gnu.org/bugzilla/show_bug.cgi?id=82174
--- Comment #2 from David Malcolm <dmalcolm at gcc dot gnu.org> --- The entry with the NULL name comes from this line in sanitizer.def: /* This has to come before all the sanitizer builtins. */ DEF_BUILTIN_STUB(BEGIN_SANITIZER_BUILTINS, (const char *)0) There's also this one at the end of sanitizer.def: /* This has to come after all the sanitizer builtins. */ DEF_BUILTIN_STUB(END_SANITIZER_BUILTINS, (const char *)0) These were added in r232891 (aka ee49ca6a1c66c03e3b8ba494c78c02f0f92de050) to fix PR lto/69254. I'm working on a fix.