[LLVMdev] Using C++'11 language features in LLVM itself

Chris Lattner clattner at apple.com
Fri Jan 11 10:46:16 PST 2013

On Jan 11, 2013, at 8:35 AM, Brooks Davis <brooks at freebsd.org> wrote:
> On Fri, Jan 11, 2013 at 08:02:22AM -0500, Justin Holewinski wrote:
>> That said, I think MSVC 2010 is a reasonable target.

Just MHO, but I think it is far too early to drop support for MSVC 2010.

> It's a bit more complex for FreeBSD (and probably the others) due to
> assumptions in our build system.

That's what I figured.  :-(    I also really don't want to inconvenience FreeBSD right when you guys have switched to Clang!

> When you do move forward with C++11 features, it would be helpful if
> you made a long term commitment to limiting the feature set to those
> features in 3.2 or whatever ever release is the last with the current
> feature set.

Yes, makes sense.  We want to have a stated goal that we build with some specific minimum compiler versions.  

> From my perspective, I'd prefer to see one more llvm release that builds
> with gcc 4.2.1 because we've very close to having ARM be self-hosting and
> having that on 9 would be a good thing.

I think that is perfectly reasonable.

Based on the discussion in this thread my proposal is this:

- LLVM 3.3 (~April/May 2013) has no C++'11 in it.
- Limited C++'11 language features becomes ok after the 3.3 release branches.
- We limit ourselves to the intersection of features supported by MSVC 2010, GCC 4.5, and Clang 3.1.
- Down the road we can reevaluate and bump up the minimums when it makes sense.

Does that seem reasonable - or at least acceptable - for everyone?


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