Is it just that it forces the stack to be “sufficiently unwindable” in a way that might make it hard to apply optimisations that significantly alter the structure of the CFG? I could see inlining and TCO being tricky perhaps?
Or does Windows use a different implementation? Not sure if it uses the Itanium ABI or something else.
“Zero overhead” refers to the actual functions code gen; there are still tables and stuff that have to be updated
Our implementation of noexcept for the single function case I think is fine now. There is a single extra bit in the exception function info which is checked by the unwinder. Other than requiring exception info in cases where we otherwise wouldn’t
The inlining case has always been both more complicated and more of a problem. If your language feature inhibits inlining in any situation you have a real problem