[PATCH] Define std::not_fn for C++17

[Jonathan Wakely]

On 19/08/16 16:46 +0100, Jonathan Wakely wrote:
>This updates std::experimental::not_fn to match the C++17 semantics
>(which are a superset of the Library Fundamentals v2 semantics) and
>then copies it to std::not_fn as well.
>
>	* doc/xml/manual/status_cxx2017.xml: Update status of not_fn.

Oops, the "fixes for not_fn" row in the table should be shown as done
too.

>	* doc/html/*: Regenerate.
>	* include/experimental/functional (_Not_fn, not_fn): Match C++17
>	semantics.
>	* include/std/functional (_Not_fn, not_fn): Define for C++17.
>	* testsuite/20_util/not_fn/1.cc: New.
>	* testsuite/experimental/functional/not_fn.cc: Test abstract class.
>	Remove test for volatile-qualified wrapper.
>
>Tested x86_64-linux, committed to trunk.

I wonder if we want to move the experimental::_Not_fn class into
<functional> and have std::not_fn and std::experimental::not_fn return
exactly the same type.