mk/compiler.mk has:

.      if defined(USE_GCC_SHLIB)
DEPENDS+=               gcc>=${GCC_REQD}:../../lang/gcc

So then even if you are using gcc3 then the registered dependencies are
like:

Registering depends: gcc>=2.95.3

So then the package really needing USE_GCC_SHLIB could end up being
installed with older or newer (or wrong) gcc libs.

So I made it:
-DEPENDS+=              gcc3>=${GCC_REQD}:../../lang/gcc3
+DEPENDS+=              gcc3=${_CC_VERSION}:../../lang/gcc3

But that makes dependencies on gcc3 meta package. Maybe its hould be more
customizable to depend on gcc3-c and gcc3-c++ if those are used instead.

Any ideas?

   Jeremy C. Reed
   http://bsd.reedmedia.net/

p.s. I am looking at this because I considered USE_GCC_SHLIB for
libtool-base.