[libstdc++ PATCH] Implement observer_ptr

[Jonathan Wakely]

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>.