[PATCH] PR libstdc++/83607 specialize Boyer-Moore searchers for std::byte

[Jonathan Wakely <jwakely at redhat dot com>]

This makes the searchers use the same optimization for std::byte as
for narrow character types, and also uses it when the predicate is
std::equal_to<C> rather than the default std::equal_to<void>.

I wanted to call the new trait __is_byte_size, for pun value, but it
isn't true for everything with size 1, because user-defined
enumeration types could have weird equality semantics that would mean
the optimization isn't valid.

	PR libstdc++/83607
	* include/std/functional (__is_byte_like): New trait.
	(__is_std_equal_to): Remove.
	(__boyer_moore_base_t): Use __is_byte_like instead of
	__is_std_equal_to.
	* include/experimental/functional (__is_std_equal_to): Remove.
	(__boyer_moore_base_t): Use __is_byte_like instead of
	__is_std_equal_to.
	* testsuite/20_util/function_objects/83607.cc: New test.

Tested powerpc64le-linux, committed to trunk.

Attachment: patch.txt
Description: Text document