Add hash_integral_test.cpp

test/Jamfile.v2

@@ -65,3 +65,4 @@ run hash_forward_list_test.cpp ;
 run quick.cpp ;
 
 run hash_number_test2.cpp ;
+run hash_integral_test.cpp ;

test/hash_integral_test.cpp

@@ -0,0 +1,75 @@
+// Copyright 2005-2009 Daniel James.
+// Copyright 2021 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/core/lightweight_test.hpp>
+#include <boost/core/type_name.hpp>
+#include <boost/type_traits/is_signed.hpp>
+#include <set>
+
+#if defined(BOOST_MSVC)
+#pragma warning(disable: 4127) // conditional expression is constant
+#endif
+
+// This test checks that small numbers hash to themselves even if
+// their type is wider than size_t
+
+template<class T>
+void identity_test()
+{
+    if( boost::is_signed<T>::value )
+    {
+        for( int i = -128; i <= 127; ++i )
+        {
+            BOOST_TEST_EQ( boost::hash<T>()( static_cast<T>( i ) ), static_cast<std::size_t>( i ) );
+        }
+    }
+    else
+    {
+        for( int i = 0; i <= 255; ++i )
+        {
+            BOOST_TEST_EQ( boost::hash<T>()( static_cast<T>( i ) ), static_cast<std::size_t>( i ) );
+        }
+    }
+}
+
+#define TEST(type) std::cerr << "Testing: " #type " (" << boost::core::type_name<type>() << ")\n"; identity_test<type>();
+
+int main()
+{
+    TEST(char)
+    TEST(signed char)
+    TEST(unsigned char)
+#ifndef BOOST_NO_INTRINSIC_WCHAR_T
+    TEST(wchar_t)
+#endif
+#ifndef BOOST_NO_CXX11_CHAR16_T
+    TEST(char16_t)
+#endif
+#ifndef BOOST_NO_CXX11_CHAR32_T
+    TEST(char32_t)
+#endif
+    TEST(short)
+    TEST(unsigned short)
+    TEST(int)
+    TEST(unsigned int)
+    TEST(long)
+    TEST(unsigned long)
+
+#if !defined(BOOST_NO_LONG_LONG)
+    TEST(boost::long_long_type)
+    TEST(boost::ulong_long_type)
+#endif
+
+#if defined(BOOST_HAS_INT128)
+    TEST(boost::int128_type)
+    TEST(boost::uint128_type)
+#endif
+
+    TEST(std::size_t)
+    TEST(std::ptrdiff_t)
+
+    return boost::report_errors();
+}