https://gcc.gnu.org/bugzilla/show_bug.cgi?id=79813 --- Comment #2 from Piers Finlayson <piers at piersandkatie dot com> --- I have reproduced on 5.2.0, but I strongly suspect some sort of build error/inconsistently, possibly to do with musl libc. I'm going to report to the toolchain maintainers - happy for you to close this.