Not a blocker anymore, considering that Martin has workarounds in place.
Only for Win64. Still need to work on W32.
But the Dwarf SEH info is of limited help if at all.
1) It is unavailable in the default gdb based debugger. And even with FpDebug on the raise, things like cross debugging (ok *nix to win may be rare-ish) are still a task for gdb (server).
2) For FpDebug, as implemented in that patch, it is not useful either.
In SEH64 "finally" is a subroutine. In the actual function their is just a "call" asm statement. The call statement is used if there is no exception. If there is an exception, the call statement is not executed.
The dwarf info pointed to that call statement.
Ok, one could disassemble the call, to find the finally sub. But that is based on assumptions about implementation detail (there is exactly one call, and it goes directly to the address, that will be hit in case of exception)
I have not yet dug deep enough to come up with how to give useful debug info via dwarf.
So having to rely on implementation detail, other methods were found to deal with it.