[libstdc++ PATCH] Implement observer_ptr

[Jonathan Wakely]

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.