[LLVMdev] RFC: Exception Handling Proposal Revised

[Sebastian Redl]

On 01.12.2010 09:25, John McCall wrote:
>
> One problem I foresee is that it's possible for a dispatch block to become unreachable from its landing pad.  If that block is then deleted, we'd lose information about what's supposed to unwind there.  This could happen if, e.g., someone had a noreturn destructor.  In languages that usefully allow throws from EH destructors (i.e. Ada) I can imagine uses for this, and regardless it's well-formed code that shouldn't cause the world to explode.
The way I understood Duncan's description of the Ada model, even an 
unconditionally throwing Ada constructor isn't exactly noreturn - or 
rather, every destructor is surrounded by its own try-catch.
Same in D, btw, which also allows throwing destructors. There, a throw 
with an in-flight exception appends the new exception to the in-flight 
chain of exceptions and keeps unwinding.

Sebastian