Add hash_number_test2

test/Jamfile.v2

@@ -63,3 +63,5 @@ run detail_is_unordered_range_test.cpp ;
 run hash_forward_list_test.cpp ;
 
 run quick.cpp ;
+
+run hash_number_test2.cpp ;

test/hash_number_test2.cpp

@@ -0,0 +1,89 @@
+// 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 <set>
+
+#if defined(BOOST_MSVC)
+#pragma warning(disable:4244) // conversion from int to float
+#endif
+
+#if defined(__GNUC__) || defined(__clang__)
+#pragma GCC diagnostic ignored "-Wconversion"
+#endif
+
+// This test checks for collisions in a small range of numbers
+
+template<class T, int M>
+void collision_test_()
+{
+    std::set<std::size_t> hashes;
+
+    for( int i = -128; i <= 127; ++i )
+    {
+        hashes.insert( boost::hash<T>()( i * M ) );
+    }
+
+    BOOST_TEST_EQ( hashes.size(), 256 );
+}
+
+template <class T>
+void collision_test()
+{
+    collision_test_<T, 1>();
+    collision_test_<T, 2>();
+    collision_test_<T, 3>();
+    collision_test_<T, 4>();
+    collision_test_<T, 5>();
+    collision_test_<T, 8>();
+    collision_test_<T, 10>();
+    collision_test_<T, 16>();
+    collision_test_<T, 32>();
+    collision_test_<T, 64>();
+    collision_test_<T, 100>();
+    collision_test_<T, 128>();
+}
+
+#define TEST(type) std::cerr << "Testing: " #type " (" << boost::core::type_name<type>() << ")\n"; collision_test<type>();
+
+int main()
+{
+#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(float)
+    TEST(double)
+    TEST(long double)
+
+    TEST(std::size_t)
+    TEST(std::ptrdiff_t)
+
+    return boost::report_errors();
+}