emerge

doc@greyskull ~ $ revdep-rebuild -p
Configuring search environment for revdep-rebuild

Checking reverse dependencies...

Packages containing binaries and libraries broken by a package update
will be emerged.

Collecting system binaries and libraries... done.
  (/home/doc/.revdep-rebuild.1_files)

Collecting complete LD_LIBRARY_PATH... done.
  (/home/doc/.revdep-rebuild.2_ldpath)

Checking dynamic linking consistency...
  broken /usr/lib/gcc/x86_64-pc-linux-gnu/3.4.6/lib-org-w3c-dom.la (requires /usr/lib/../lib64/libgcj.la)
  broken /usr/lib/gcc/x86_64-pc-linux-gnu/3.4.6/lib-org-xml-sax.la (requires /usr/lib/../lib64/libgcj.la)
  broken /usr/lib/gcc/x86_64-pc-linux-gnu/4.1.1/libgcjawt.la (requires /usr/lib/../lib64/lib-gnu-java-awt-peer-gtk.la)
  broken /usr/lib/gcc/x86_64-pc-linux-gnu/4.1.1/libgij.la (requires /usr/lib/../lib64/libgcj.la)
  broken /usr/lib64/gcc/x86_64-pc-linux-gnu/3.4.6/lib-org-w3c-dom.la (requires /usr/lib/../lib64/libgcj.la)
  broken /usr/lib64/gcc/x86_64-pc-linux-gnu/3.4.6/lib-org-xml-sax.la (requires /usr/lib/../lib64/libgcj.la)
  broken /usr/lib64/gcc/x86_64-pc-linux-gnu/4.1.1/libgcjawt.la (requires /usr/lib/../lib64/lib-gnu-java-awt-peer-gtk.la)
  broken /usr/lib64/gcc/x86_64-pc-linux-gnu/4.1.1/libgij.la (requires /usr/lib/../lib64/libgcj.la)
 done.
  (/home/doc/.revdep-rebuild.3_rebuild)

Assigning files to ebuilds... done.
  (/home/doc/.revdep-rebuild.4_ebuilds)

Evaluating package order... done.
  (/home/doc/.revdep-rebuild.5_order)

All prepared. Starting rebuild...
emerge --oneshot -p =sys-devel/gcc-4.1.1-r3 

These are the packages that would be merged, in order:

Calculating dependencies... done!
[ebuild   R   ] sys-devel/gcc-4.1.1-r3  
Now you can remove -p (or --pretend) from arguments and re-run revdep-rebuild.
doc@greyskull ~ $