Add hash_string_test2

test/Jamfile.v2

@@ -86,3 +86,4 @@ explicit container_hash/hash_no_generic_float ;
 build-project ../examples ;
 
 run hash_reference_values.cpp ;
+run hash_string_test2.cpp ;

test/hash_string_test2.cpp

@@ -0,0 +1,34 @@
+// Copyright 2022 Peter Dimov.
+// Distributed under the Boost Software License, Version 1.0.
+// https://www.boost.org/LICENSE_1_0.txt
+
+#include <boost/container_hash/hash.hpp>
+#include <boost/utility/string_view.hpp>
+#include <boost/core/lightweight_test.hpp>
+#include <boost/config.hpp>
+#include <string>
+#if !defined(BOOST_NO_CXX17_HDR_STRING_VIEW)
+#include <string_view>
+#endif
+
+// Test whether the hash values of a string and a
+// string_view that refers to it match. This is
+// important for unordered heterogeneous lookups.
+
+template<class T> std::size_t hv( T const& t )
+{
+    return boost::hash<T>()( t );
+}
+
+int main()
+{
+    std::string s( "Test." );
+
+    BOOST_TEST_EQ( hv( s ), hv( boost::string_view( s ) ) );
+
+#if !defined(BOOST_NO_CXX17_HDR_STRING_VIEW)
+    BOOST_TEST_EQ( hv( s ), hv( std::string_view( s ) ) );
+#endif
+
+    return boost::report_errors();
+}