Here are some build/test results for the 4.2.0 release.
#1: i686-pc-linux-gnu on RHEL 3, booted with gcc 3.4.2
(all languages except Ada).
http://gcc.gnu.org/ml/gcc-testresults/2007-05/msg00713.html
(NOTE: booting with the RHEL-supplied compiler fails the
compare).
#2: x86_64-unknown-linux-gnu on RHEL 3, booted with Red Hat's
3.2.3 (all languages except Ada).
http://gcc.gnu.org/ml/gcc-testresults/2007-05/msg00710.html
#3: sparc-sun-solaris2.8: failure in building jv-convert (while
building libjava).
Test result for languages other than Java or Ada:
http://gcc.gnu.org/ml/gcc-testresults/2007-05/msg00714.html
The failure I got was
/bin/ksh ./libtool --tag=GCJ --mode=link
/remote/atg5/jbuck/gcc-4.2.0-sol2-build/gcc/gcj
-B/remote/atg5/jbuck/gcc-4.2.0-sol2-build/sparc-sun-solaris2.8/libjava/
-B/remote/atg5/jbuck/gcc-4.2.0-sol2-build/gcc/
-L/remote/atg5/jbuck/gcc-4.2.0-sol2-build/sparc-sun-solaris2.8/libjava -g -O2
-o jv-convert --main=gnu.gcj.convert.Convert -rpath /u/jbuck/cvs.sol2/4.2.0/lib
-shared-libgcc
-L/remote/atg5/jbuck/gcc-4.2.0-sol2-build/sparc-sun-solaris2.8/libjava/.libs
libgcj.la
/remote/atg5/jbuck/gcc-4.2.0-sol2-build/gcc/gcj
-B/remote/atg5/jbuck/gcc-4.2.0-sol2-build/sparc-sun-solaris2.8/libjava/
-B/remote/atg5/jbuck/gcc-4.2.0-sol2-build/gcc/ -g -O2 -o .libs/jv-convert
--main=gnu.gcj.convert.Convert -shared-libgcc
-L/remote/atg5/jbuck/gcc-4.2.0-sol2-build/sparc-sun-solaris2.8/libjava
-L/remote/atg5/jbuck/gcc-4.2.0-sol2-build/sparc-sun-solaris2.8/libjava/.libs
./.libs/libgcj.so
-L/remote/atg5/jbuck/gcc-4.2.0-sol2-build/sparc-sun-solaris2.8/libstdc++-v3/src
-L/remote/atg5/jbuck/gcc-4.2.0-sol2-build/sparc-sun-solaris2.8/libstdc++-v3/src/.libs
-lpthread -lrt -ldl -L/remote/atg5/jbuck/gcc-4.2.0-sol2-build/./gcc
-L/usr/ccs/lib -lgcc_s -lgcc_s -Wl,--rpath -Wl,/u/jbuck/cvs.sol2/4.2.0/lib
/u/jbuck/gnu.sol2/bin/ld: unrecognized option '-Wl,-rpath'
/u/jbuck/gnu.sol2/bin/ld: use the --help option for usage information
collect2: ld returned 1 exit status
/u/jbuck/gnu.sol2/bin/ld is GNU ld version 2.17.
