[llvm-dev] Using C++14 code in LLVM

[C Bergström via llvm-dev]

On Mon, Oct 3, 2016 at 12:37 AM, Zachary Turner via llvm-dev
<llvm-dev at lists.llvm.org> wrote:
>
>
> On Sat, Oct 1, 2016 at 11:46 PM Joerg Sonnenberger via llvm-dev
> <llvm-dev at lists.llvm.org> wrote:
>>
>> On Sun, Oct 02, 2016 at 05:33:40AM +0000, Zachary Turner via llvm-dev
>> wrote:
>> > While GCC doesn't claim to "fully" support C++14 until 5.2 (which is
>> > only
>> > about 1 year old), you can get all of the above features with GCC 4.9
>>
>> I do care quite a bit about GCC 4.8 support, since that's what is
>> shipped with NetBSD 7.
>>
>> > One potentially added benefit of this is that GCC supports <regex> in
>> > 4.9.
>> > This might allow us to kill of llvm::Regex in favor of standardizing on
>> > std::regex, as GCC is currently the only supported compiler without a
>> > regex
>> > implementation.
>>
>> If that is the only argument, we should be able to reuse the libc++
>> implementation without too much trouble?
>
>
> That wasn't even the main argument :)  The main argument was the ability to
> use C++14 in the upstream.  I suspect that we won't want to be tied to C++11
> indefinitely though.  LLVM already has a section called "Getting a modern
> host C++ toolchain" for distros with older GCC's.  In theory this could just
> be bumped from "older than GCC 4.7" to "older than GCC 4.9".  I admit I
> don't know much (i.e. anything) about NetBSD.  But a quick look at the
> release history says that even NetBSD 8 (which isn't even stable yet), is
> still only going to have GCC 4.8.  So if we're going to be held back by
> this, we're looking at 2-4 years before we can use C++14 upstream.  Just
> food for thought.

Jörg, other than just time and energy - what's the (big?) technical
challenge or bug list which prevents NetBSD from doing something
radical like going to a really modern version of gcc? (I realize
NetBSD tends to be very conservative, which isn't a bad thing) I've
never had access to NetBSD 1st hand, but is very modern gcc available
in "ports"?