[PATCH] PR78052 Define std::allocator<void>::{construct,destroy}

[Jonathan Wakely <jwakely at redhat dot com>]

This let's std::allocator<void> be used in situations like:

std::allocate_shared<int>(std::allocator<void>(), 1);

where a "proto-allocator" is required. The other members such as
allocate() and max_size() don't make sense for void, but construct and
destroy don't depend on value_type.

	PR libstdc++/78052
	* include/bits/allocator.h (allocator<void>::construct)
	(allocator<void>::destroy): Define.
	* testsuite/20_util/allocator/void.cc: New test.

Tested x86_64-linux, committed to trunk. Also applying to gcc-5 and
gcc-6 branches, because this used to work before I put in the
allocator_traits<allocator<T>> partial specialization.

Attachment: patch.txt
Description: Text document