during a build trying gcc-3, i encountered this error (which i think
another person reported, but i can not find that mail):

dependall ===> gnu/usr.bin/gcc3/backend
cc -O -I. -I/u1/src/gnu/usr.bin/gcc3/backend/../arch/sparc64 -DIN_GCC -DHAVE_CONFIG_H -I/u1/src/gnu/dist/gcc/gcc -I/u1/src/gnu/dist/gcc/gcc/. -I/u1/src/gnu/dist/gcc/gcc/config -I/u1/src/gnu/dist/gcc/gcc/../include -I/u1/src/gnu/usr.bin/gcc3/backend/.. -c /u1/src/gnu/dist/gcc/gcc/gengenrtl.c
In file included from /u1/src/gnu/dist/gcc/gcc/gengenrtl.c:29:
/u1/src/gnu/dist/gcc/gcc/real.h:67: size of array `test_real_width' is negative
*** Error code 1

Stop.
nbmake: stopped in /u1/src/gnu/usr.bin/gcc3/backend

sparc64/auto-build.h has SIZEOF_LONG as 4 bytes, rather than 8.

If i understand correctly, one has to bootstrap the compiler in
src/tools/gcc to recreate this/these files.  is that correct?

I have not gone through that process yet, so I do not know why
SIZEOF_LONG had the value 4.