https://gcc.gnu.org/bugzilla/show_bug.cgi?id=67728
--- Comment #2 from Brett Neumeier <bneumeier at gmail dot com> --- Thanks for your swift comment! I disagree that the bug is in ISL. The problem is that gmp, although the build appears successful, is *not* correctly built. Six object files that should be compiled and linked into gmplib.a are not built because they are only built correctly when assembly is enabled. One of those is invert_limb.o, which contains the symbol __gmpn_invert_limb, which is needed by ISL. So the *bug* is in the GMP build, but the *consequence* of the bug is that ISL cannot be linked. I agree that my patch is not adequate, though -- I just tested and found that I couldn't build an x86_64-to-arm cross-gcc when my patch is installed. The configure for GMP crashes with: configure: error: --target is not appropriate for GMP Use --build=CPU-VENDOR-OS if you need to specify your CPU and/or system explicitly. Use --host if cross-compiling (see "Installing GMP" in the manual for more on this). Obviously the best way to address this situation is by getting GMP to build properly for all architectures regardless of whether assembly is enabled. Until or unless that's done, though, it seems like it would be worthwhile to do *something* to address the issue on the GCC side, since that's where I (and others, according to google) have tripped over it. Maybe a documentation change, to say that GMP shouldn't be built in-tree when cross-compiling GCC? Or something of that sort?
