[libstdc++ PATCH] Implement observer_ptr

[Ed Smith-Rowland]

On 05/02/2015 05:42 AM, Jonathan Wakely wrote:
> On 02/05/15 10:40 +0100, Jonathan Wakely wrote:
>> On 01/05/15 22:02 -0400, Ed Smith-Rowland wrote:
>>> On 05/01/2015 05:01 PM, Jonathan Wakely wrote:
>>>> On 01/05/15 16:37 +0300, Ville Voutilainen wrote:
>>>>> Tested on Linux-x64.
>>>>>
>>>>>  Implement observer_ptr.
>>>>
>>>> Thanks! Committed with some minor formatting changes.
>>>>
>>>> I've also committed this to add feature-test macros and update the
>>>> docs. Tested powerpc64le-linux, committed to trunk.
>>>>
>>>>
>>> I pretty sure we're supposed to add the macro for *all* the headers 
>>> that got enable_if.
>>
>> That's not how I read the Fundamentals TS:
>>
>> Programmers who wish to determine whether a feature is available in
>> an implementation should base that determination on the presence of
>> the header (determined with __has_include(<header/name>)) and the
>> state of the macro with the recommended name.
>>
>> And the header for erase_if is listed as <experimental/vector>.
>
>
> And SD-6 says:
>
>  For library features, the “Header“ column identifies the header that
>  is expected to define the macro, although the macro may also be
>  predefined.
>
>
>
OK.  Thanks.

I do remember an SD-6 discussion about how annoying the 
define-the-macro-in-all-relevant-headers was.
I didn't know there was a resolution.  I need to reeducate myself.
Meanwhile I'll rollback my patch.

Reverted in 222722.

I'll ask next time.
Sorry for the noise.

Ed