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From: Alexander Terekhov (terekhov_at_[hidden])
Date: 2007-11-02 10:04:09

Anthony Williams wrote:
> N2420 (
> covers some of the relevant ground --- it's the minutes of the POSIX/C++
> liaison committee.

"Gnu gcc and Solaris pthreads: The Gnu gcc and Solaris pthreads
implementations are two known implementations that attempt to map
POSIX pthread cancellation onto C++ exception handling, but both
do so at the cost of breaking the exception model (i.e., they no
longer conform to ISO C++) because the alternative appears to be
that C++ destructors and catch blocks would not be invoked for
cancellation which would mean that resources would be leaked."

Uhmm. Don't know about (modern) Solaris, but glibc (presumably
that is meant by "Gnu gcc pthreads implementation") does invoke
C++ destructors and catch blocks. But instead of using ordinary
exceptions, it uses "forced unwinding" for thread cancel and
exit. For some unknown reason (other than "I say it must be
so"), glibc maintainer Drepper of Red Hat simply refuses to
even contemplate changing it to use ordinary exceptions instead
of "forced unwinding"... and I suspect that is the reason why
WG21 was asked to drop standardization of thread cancel (and exit)
as exceptions.


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