On Mon, 18 Nov 2019, Rainer Orth wrote: > So you certainly need such an effective-target test and, at least as > importantly, a configure test at build time that you can assemble, link, > and run a test correctly before enabling it in gcc. Just > unconditionally dropping it into elfos.h is wrong.
Tests in gcc/configure for linking or running something are a bad idea because they don't work for cross compilation (at all, for run tests; when bootstrapping and target libc hasn't been built, for link tests). I'd assume any bare-metal ELF target used with GNU binutils *could* support symbol versioning if it happens to be used with an RTOS that has a dynamic linker with that support, even if in fact it's much more likely to be used with static linking only. So I don't think the information is available when GCC is built, beyond (a) it's definitely not supported for non-ELF targets (as determined through by a list of targets such as in config/elf.m4:ACX_ELF_TARGET_IFELSE) and (b) there might be a list of ELF OS targets known to lack support. -- Joseph S. Myers jos...@codesourcery.com