[LLVMdev] [cfe-dev] RFC: A proposal to move toward using C++11 features in LLVM & Clang / bounding support for old host compilers

[Chandler Carruth]

On Mon, Oct 28, 2013 at 4:47 PM, "C. Bergström" <cbergstrom at pathscale.com>wrote:

> For those driving c++11 in clang/llvm - Would it generally be acceptable
> to have a "sunrise" period where the preliminary evaluation has been done
> (buildbots, compiler evaluate.. etc) and the 1st actual c++11 commit hits
> the repo. (30-60 days?)
>

I really don't think we need this level of complexity to the planning. I
think we can give a heads up at a high level (as already discussed), check
the build bots are updated, and flip the switch.


> -------------
> My concern/thoughts - When we swap out STDCXX for libc++ - We aren't able
> to self host clang.
>

No part of this relies on using libc++ on Linux instead of libstdc++.
That's an orthogonal issue which I'm not even attempting to address.

Certainly, the platforms with only libc++ are self hosting clang
successfully today.


> This could be entirely *our* fault, but it hasn't been investigated
> extensively. (We also see Perennial C++ testsuite regressions which appear
> to come from libc++, but also not investiaged/confirmed) Having a sunrise
> period would allow us to investigate this as well as report any potentially
> blocking problems.
>
> Having a gnu-free self hosting[1] policy attached to this would also be
> great - that makes a potentially easier backup solution to anyone on
> [linux] with older gnu compilers
>

Absolutely not. I really don't want to tie this to more things. If you
think we should pursue such a goal, fine, but it is independent of the
decision about using C++11, and not something I'm currently striving for.
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