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

[Aaron Ballman]

On Sun, Oct 27, 2013 at 5:09 PM, Chris Lattner <clattner at apple.com> wrote:
> On Oct 27, 2013, at 12:07 PM, Óscar Fuentes <ofv at wanadoo.es> wrote:
>> Chris Lattner <clattner at apple.com> writes:
>>
>>>> One short term caveat: Windows is special.
>>
>> s/Windows/Visual Studio.
>>
>> MinGW has the latest and greatest gcc.
>>
>>> I don't see how it is special.
>>
>> It is special, sadly, and I'm not talking about C++11 support only, but
>> about the policies MS follows which too often makes very inconvenient
>> (or even impossible) to upgrade to newer VS versions. The latest example
>> that comes to mind was the release of VS2012: they removed Windows XP
>> support, as if upgrading the OS is a non-issue if you ask for it to your
>> users on a polite tone. An uproar followed and they backpedaled on a
>> service pack some months later, but that not always happens.
>
> I'm sorry, let me clarify.  I'm saying that MSVC shouldn't be special from an LLVM policy perspective.  We shouldn't have a general rule with an exception for MSVC: we should have a general rule that includes MSVC user's requirements as well.
>
> This is why I don't like a general rule of "anything older than 2 years isn't supported".
>
>>>> Now for the carrot: if we go with this plan, then immediately after
>>>> branching for 3.4, we would be able to use the vast majority of
>>>> C++11 features, targeting the following as the oldest toolchains
>>>> supported through the 3.5 release timeframe:
>>>>
>>>> GCC 4.7
>>>> Clang 3.1
>>>> VS 2012
>>>
>>> This seems overly aggressive to me. Why not start by baselining at
>>> VC++ 2010, and bump up everything else to match?
>>
>> IIRC the only significant difference among VS 2012 and VS 2010 is range
>> for loops.
>
> Which is really sad, given how nice they are, but I think it would be huge progress to move LLVM 3.4 to require the VS 2010 feature set (and the corresponding GCC/clang/etc versions).  We can move up to VS 2012 as a second step and second discussion.

I may be remembering incorrectly, but I thought we already supported
only VS2010 and higher today.  AFAIK, there are no 2008 build bots as
part of the process, and I've not seen a 2008-specific patch for
compatibility in ages.

~Aaron