[libcxx-dev] Question: Why are std::exception & friends not in a versioned namespace?

Richard Smith via libcxx-dev libcxx-dev at lists.llvm.org
Fri Oct 19 12:18:50 PDT 2018


On Wed, 17 Oct 2018 at 11:44, Ben Craig via libcxx-dev <
libcxx-dev at lists.llvm.org> wrote:

> "Magic" types that the compiler / core language know about don't go in the
> versioned namespace.
>

That certainly applies to things like std::type_info,
std::initializer_list, and std::bad_alloc, but std::exception is not
special in this regard.

Rather, I think the reason we don't version std::exception is so that in
code that mixes use of libc++ and libstdc++, one can throw an exception
derived from std::exception using one library and catch it using the other
library. (A special case of that: the default 'terminate' handler can print
out details of the thrown exception if it's derived from std::exception,
even if it's using the std::exception from a different stdlib.)


> > -----Original Message-----
> > From: libcxx-dev <libcxx-dev-bounces at lists.llvm.org> On Behalf Of Louis
> > Dionne via libcxx-dev
> > Sent: Wednesday, October 17, 2018 1:33 PM
> > To: libcxx-dev at lists.llvm.org
> > Subject: [libcxx-dev] Question: Why are std::exception & friends not in a
> > versioned namespace?
> >
> > The title of the message pretty much says everything. I’m wondering why
> > `std::exception` is not `std::__1::exception` instead — most symbols are
> in
> > the  versioned namespace, but not this one.
> >
> > Thanks,
> > Louis
> >
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