18_support/nested_exception/rethrow_if_nested-term.cc

[Iain Sandoe]

Hi Jonathan,

> On 20 Aug 2023, at 12:21, Jonathan Wakely <jwakely@redhat.com> wrote:
> 
> On Sun, 20 Aug 2023 at 11:08, Iain Sandoe <iain@sandoe.co.uk> wrote:

> 
>> So, ISTM that the difference is not in the actual nested exception handling (including the conditional rethrow) but lies, instead in a different interpretation of when the changes from set_terminate() take effect.
> 
> I don't think it's when the changes take effect, that has to be
> instant (i.e. get_terminate() must return the new handler
> immediately). It's whether std::terminate() actually uses the result
> of std::get_terminate() or uses the active exception's stored handler.

It would seem the latter (but I did not read the code so far).

>> — it needs someone with state on the history of this to comment …
>> 
>> a) does that seem like a reasonable analysis?
>> b) would it be acceptable to move the set_terminate () call?
> 
> I didn't intend this test to depend on unspecified behaviour. But just
> moving it before the throw would mean that if std::throw_with_nested
> terminates for some reason, we would exit cleanly and the test would
> pass, which we don't want.

right.

> I would prefer the attached change instead. I assume this works with
> both runtimes?
> (This also gives a FAIL if throw_with_nested returns normally for some
> reason, which would also currently PASS.)

Yes, it works with GCC (supc++) clang (main at least) and GCC (c++abi WIP)
thanks
Iain