[cfe-dev] RFC: We should take a more conservative approach to libstdc++ compatibility...

[Eric Christopher]

On Thu, Jan 10, 2013 at 7:34 PM, Chandler Carruth <chandlerc at gmail.com>wrote:

> Greetings all! This is the result of a chat between Richard and myself
> just now.
>
> These days Clang does a great job of detecting GCC and libstdc++
> installations and using them... such a great job that Clang installed today
> will work with GCC 4.9 if such a thing existed and were installed.
>
> As we've noticed recently, this can cause problems, and now that we have
> clang releases and GCC releases with decent compatibility out in the wild
> (3.2 and 4.{6,7} resp.), I think we should take a different approach:
>
> 1) Set a max GCC version we use, and on trunk have it be silly (v99.99.99).
> 2) On the release branch, lower this to the highest GCC version we test
> that release against. This protects a released clang from using newer GCC
> libstdc++ which is both good and bad -- no improvements from updates, but
> no breakage from updates.
> 3) Teach the driver about incompatible versions of GCC and libstdc++, and
> have it try to find a different version when available. (Mostly relevant to
> 4.4 and 4.5 and C++11 headers...)
> 4) Teach Clang itself to warn on a libstdc++ version macro which is one of
> the versions that has incompatibilities so users understand what is
> happening.
>
>
> Thoughts?
>

Seems totally reasonable here.

-eric


>
>
-------------- next part --------------
An HTML attachment was scrubbed...
URL: <http://lists.llvm.org/pipermail/cfe-dev/attachments/20130110/035e62ab/attachment.html>