PR libstdc++/56267
	* include/bits/hashtable.h (__cache_default): Do not depend on
	whether the hash function is DefaultConstructible or CopyAssignable.
	(_Hashtable): Adjust static assertions.
	* doc/xml/manual/containers.xml (containers.unordered.cache): Update.
	* testsuite/23_containers/unordered_set/instantiation_neg.cc: Adjust
	dg-error line number.
	* testsuite/23_containers/unordered_set/
	not_default_constructible_hash_neg.cc: Remove.

From-SVN: r206904