Hi Karl,
I've just investigated a GCC bug report about a comparison failure on
Solaris/SPARC:
PR target/88535
sparcv9 gcc 7 causes comparison failure in sparc gcc 8 dwarf2out.o
https://gcc.gnu.org/bugzilla/show_bug.cgi?id=88535
where config.guess failed to notice that the build compiler was
64-bit-default, while the host/target was 32-bit-default.
This doesn't happen with the config.guess/config.sub currently bundled
with gcc mainline (2018-06-26 resp. 2018-07-03) where with a
64-bit-default gcc x86_64-pc-solaris2.11 is determined, while with
CC='gcc -m32' I get i386-pc-solaris2.11 just as expected.