[dmd-internals] Relation between D and C++ exception handling on Windows

[Don Clugston]

Consider this simple program:
----
void main()
{
    try {
        throw new Exception("xxx");
    }
    catch (Exception e) {}
}
---
The map file includes these functions:

test0.map: 0002:0000D838       ?__internal_cpp_framehandler@@YA?AW4_EXCEPTION_DI
SPOSITION@@PAUfunc_data@@PAU_EXCEPTION_RECORD@@PAU_CPP_Establisher_Frame@@PAU_CO
NTEXT@@PAX at Z 0040F838
test0.map: 0002:0000D814       __cpp_framehandler         0040F814
test0.map: 0002:0000D814       __cpp_framehandler         0040F814
test0.map: 0002:0000D838       ?__internal_cpp_framehandler@@YA?AW4_EXCEPTION_DI
SPOSITION@@PAUfunc_data@@PAU_EXCEPTION_RECORD@@PAU_CPP_Establisher_Frame@@PAU_CO
NTEXT@@PAX at Z 0040F838

I don't like this at all. Why is the C++ exception handler being
linked into a D program?
This is important, because the C++ exception behaviour is different to D.
I've just spent the best part of a week trying to track down bug 1513
("try/catch/finally misbehavior on windows"), which has turned out to
be the most difficult bug I've ever seen.
 I'm finding it extremely difficult since the Microsoft documentation
is practically non-existent, and DMC seems to have a unique
implementation. Now I'm starting to suspect that part of the C++
exception handling mechanism may be involved, which would be bad.

Quick question to Walter -- is it possible that the D exception
handlers are sometimes called from the C++ handler?