Re: [boost] Re: boost::execution_monitor impl under windows

From: Peter Dimov (pdimov_at_[hidden])
Date: 2003-10-08 13:49:00

Alexander Terekhov wrote:
> Peter Dimov wrote:
>>
>> This doesn't play well with exception specifications since,
>
> Those are pretty much broken anyway.
>
>
http://groups.google.com/groups?selm=m.collett-E982F8.12450216072002%40lust.ihug.co.nz
> http://groups.google.com/groups?threadm=3D3547BE.3045A2A6%40web.de
> (Subject: Re: Is internal catch-clause rethrow standard?)
>
>> if I understand
>> them correctly, (and I have no reason to, since I've never used one
>> or seen one used,) a violated exception specification is required to
unwind,
>> _then_ call unexpected(), which can then rethrow a different,
"conforming",
>> exception.
>
> That needs some fixing, right. std::unexpected() shall be invoked at
> throw point (as kinda "side effect" of throw-expression).

Consider:

void f() throw(X); // calls g
void g() throw(Y); // calls h
void h() throw(Z); // throws Z();

The Z exception hits the throw(Y) wall; unexpected() eats the Z and throws
Y. Y hits throw(X), unexpected() now throws a X.

If you invoke unexpected() before the unwinding, there is no way you can get
an exception to escape through the three ex.specs.