Please include the following patch: https://sourceforge.net/p/dbus-cplusplus/bugs/18/ Reproducible: Always
Considering it's a >7 years old patch, some context would help. Hardly anything in Gentoo depend on dbus-c++, I assume you're using the library yourself? Did you already try the patch?
Yes I do. Had exactly same issue, googled, found this patch, applied and sigsegv went away.