https://gcc.gnu.org/bugzilla/show_bug.cgi?id=91034
--- Comment #16 from Andrew Roberts <andrewm.roberts at sky dot com> ---
That kicks a memory loose, from my build script:
# sed needed for GMP >=5.1 && < 6.2.0 on ARM otherwise isl build fails with
# undefined symbol __gmpn_invert_limb
sed -ixx "s/none-/${uname_m}-/" Makefile
Building natively on arm was failing using the host set to none-*-*.
none-*-* seems to work ok on Raspbian on the pi4. And it fails if you alter it,
although as I'm altering to uname -m, which gives armv7l, this would explain
some things. But not why a vanilla gcc-8.3.0 and 9.1.0 built with system gmp
can be used to rebuild themselves using the above sed and intree gmp.
However all my other arm machines (odroid-c2, odroid-xu4, rpi zero, rpi b, rpi
3b) all need this fix to build. They are running arch linux arm.
I'll recheck on the faster ones in the next few days, with both 8.3.0 and
9.1.0, to confirm if that is still the case.
