dev-vcs/subversion-1.9.4 wasn't able to compile with sys-libs/db-6.0: [...] /bin/sh "/var/tmp/portage/dev-vcs/subversion-1.9.4/work/subversion-1.9.4/libtool" --tag=CC --silent --mode=compile x86_64-pc-linux-gnu-gcc -std=c90 -DLINUX -D_REENTRANT -D_GNU_SOURCE -march=k8 -mtune=k8 -O2 -pipe -pthread -march=k8 -mtune=k8 -O2 -pipe -I./subversion/include -I./subversion -I/usr/include/apr-1 -I/usr/include/apr-1 -I/usr/include/db4.2 -I/usr/include/db6.0 -I/usr/include/serf-1 -o subversion/svn/upgrade-cmd.lo -c subversion/svn/upgrade-cmd.c /bin/sh "/var/tmp/portage/dev-vcs/subversion-1.9.4/work/subversion-1.9.4/libtool" --tag=CC --silent --mode=compile x86_64-pc-linux-gnu-gcc -std=c90 -DLINUX -D_REENTRANT -D_GNU_SOURCE -march=k8 -mtune=k8 -O2 -pipe -pthread -march=k8 -mtune=k8 -O2 -pipe -I./subversion/include -I./subversion -I/usr/include/apr-1 -I/usr/include/apr-1 -I/usr/include/db4.2 -I/usr/include/db6.0 -I/usr/include/serf-1 -o subversion/svn/util.lo -c subversion/svn/util.c /var/tmp/portage/dev-vcs/subversion-1.9.4/work/subversion-1.9.4/subversion/libsvn_fs_base/.libs/libsvn_fs_base-1.so: undefined reference to `db_create_4002' I have both db-4.2 and db-6.0 installed on my system. I had to set (as I was advised to at the beginning of the ebuild) SVN_BDB_VERSION="4.2" in my make.conf, and then things worked. (Things didn't work if I set it to "6.0".) I'm not sure if the dependencies should restrict berkeley db to version 4?
Please attach the full build log and the output of emerge --info.