Very vague compiler error message

[Jeremy DeHaan via Digitalmars-d-learn]

I recently got this error messege when building my library:

dmd: cppmangle.c:154: void 
CppMangleVisitor::cpp_mangle_name(Dsymbol*): Assertion `0' failed.

I have no idea what it means and haven't found much information 
about it. I think I have narrowed it down to the file that is 
giving this error, but does anyone know what the heck causes 
something like this?  Talk about a nondescript error.