[cfe-dev] auto and decltype availability

Chris Lattner clattner at apple.com
Fri Jul 15 16:40:40 PDT 2011

On Jul 15, 2011, at 2:05 PM, Michael Price wrote:

> I think that is a perfectly fine recommendation, but this isn't for writing code.  This is for letting people know which version of the compiler first introduced a certain feature.  For instance, if we want to use static_assert, we may (depending on other feature availability) only want to update to the version of clang that supported the features that we desire.
> It's hard to convince managers that we should update (or even switch compilers) if we have to respond with "use __has_feature in the code".

Ok, are you asking about llvm.org compilers, apple compilers, someone else's compilers?  Everyone has their own versioning scheme :).


> On Fri, Jul 15, 2011 at 1:38 PM, Chris Lattner <clattner at apple.com> wrote:
> On Jul 15, 2011, at 9:11 AM, Michael Price wrote:
> > Does anyone know which released version first had the auto and decltype features 'turned on'? And generally speaking, is there an easy way to determine this for any given C++0x feature?
> >
> > For some background, I'm working on a series of C++0x presentations at the company I work for, and at the end of every presentation I have a chart that shows the availability of the features I discussed that day.  Currently we are not using clang, but I have an entry for it because I want to show that clang is trying to keeping pace with GCC and surpassing IBM XL C/C++ and Sun Studio.
> Hi Michael,
> We recommend that people write code that uses __has_feature to check for a feature, not compare against a compiler version number.  These are documented here:
> http://clang.llvm.org/docs/LanguageExtensions.html#feature_check
> -Chris

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