Implement P0599 - noexcept for hash functions

[mclow.lists]

Summary

Mark most of the hash functions provided by libc++ as noexcept; the exceptions being optional and variant.
Tests to ensure this.

There's still some investigation to be done on unique_ptr and fancy pointer support, but that can come later.

[mclow.lists]

Add missing include to the thread::id test and mark unique_ptrs hash as not noexcept.

[EricWF]

LGTM. Although it would be useful to test that hash<variant<...>> and hash<optional<T>> do not have noexcept call operators.

Alternatively should we make hash conditionally noexcept for variant and optional?

[mclow.lists]

Committed as revision 298573

include/optional

     typedef size_t        result_type;
 
     _LIBCPP_INLINE_VISIBILITY
-    result_type operator()(const argument_type& __opt) const _NOEXCEPT
+    result_type operator()(const argument_type& __opt) const
     {
         return static_cast<bool>(__opt) ? hash<remove_const_t<_Tp>>()(*__opt) : 0;
     }

include/thread

     : public unary_function<__thread_id, size_t>
 {
     _LIBCPP_INLINE_VISIBILITY
-    size_t operator()(__thread_id __v) const
+    size_t operator()(__thread_id __v) const _NOEXCEPT
     {
         return hash<__libcpp_thread_id>()(__v.__id_);
     }

include/variant

   using result_type = size_t;
 
   inline _LIBCPP_INLINE_VISIBILITY
-  result_type operator()(const argument_type&) const {
+  result_type operator()(const argument_type&) const _NOEXCEPT {
     return 66740831; // return a fundamentally attractive random value.
   }
 };

test/std/containers/sequences/vector.bool/vector_bool.pass.cpp

     typedef std::hash<T> H;
     static_assert((std::is_same<H::argument_type, T>::value), "" );
     static_assert((std::is_same<H::result_type, std::size_t>::value), "" );
-
+    ASSERT_NOEXCEPT(H()(T()));
+    
     bool ba[] = {true, false, true, true, false};
     T vb(std::begin(ba), std::end(ba));
     H h;

     typedef std::hash<T> H;
     static_assert((std::is_same<H::argument_type, T>::value), "" );
     static_assert((std::is_same<H::result_type, std::size_t>::value), "" );
+    ASSERT_NOEXCEPT(H()(T()));
     bool ba[] = {true, false, true, true, false};
     T vb(std::begin(ba), std::end(ba));
     H h;

test/std/diagnostics/syserr/syserr.hash/error_code.pass.cpp

     typedef std::hash<T> H;
     static_assert((std::is_same<H::argument_type, T>::value), "" );
     static_assert((std::is_same<H::result_type, std::size_t>::value), "" );
+    ASSERT_NOEXCEPT(H()(T()));
     H h;
     T ec(i, std::system_category());
     const std::size_t result = h(ec);

test/std/diagnostics/syserr/syserr.hash/error_condition.pass.cpp

     typedef std::hash<T> H;
     static_assert((std::is_same<H::argument_type, T>::value), "" );
     static_assert((std::is_same<H::result_type, std::size_t>::value), "" );
+    ASSERT_NOEXCEPT(H()(T()));
     H h;
     T ec(i, std::system_category());
     const std::size_t result = h(ec);

test/std/strings/basic.string.hash/strings.pass.cpp

 #include <cassert>
 #include <type_traits>
 
+#include "test_macros.h"
+
 template <class T>
 void
 test()

     typedef std::hash<T> H;
     static_assert((std::is_same<typename H::argument_type, T>::value), "" );
     static_assert((std::is_same<typename H::result_type, std::size_t>::value), "" );
+    ASSERT_NOEXCEPT(H()(T()));
+
     H h;
     std::string g1 = "1234567890";
     std::string g2 = "1234567891";

test/std/strings/string.view/string.view.hash/string_view.pass.cpp

 #include <cassert>
 #include <type_traits>
 
+#include "test_macros.h"
+
 using std::string_view;
 
 template <class SV>

     typedef typename SV::value_type char_type;
     typedef std::basic_string<char_type> String;
     typedef std::hash<String> SH;
+    ASSERT_NOEXCEPT(H()(SV()));
 
     char_type g1 [ 10 ];
     char_type g2 [ 10 ];

test/std/thread/thread.threads/thread.thread.class/thread.thread.id/thread_id.pass.cpp

     typedef std::hash<std::thread::id> H;
     static_assert((std::is_same<typename H::argument_type, std::thread::id>::value), "" );
     static_assert((std::is_same<typename H::result_type, std::size_t>::value), "" );
+    ASSERT_NOEXCEPT(H()(id2));
     H h;
     assert(h(id1) != h(id2));
 }

test/std/utilities/function.objects/unord.hash/enum.pass.cpp

     typedef std::hash<T> H;
     static_assert((std::is_same<typename H::argument_type, T>::value), "" );
     static_assert((std::is_same<typename H::result_type, std::size_t>::value), "" );
+    ASSERT_NOEXCEPT(H()(T()));
     typedef typename std::underlying_type<T>::type under_type;
 
     H h1;

test/std/utilities/function.objects/unord.hash/floating.pass.cpp

 #include <limits>
 #include <cmath>
 
+#include "test_macros.h"
+
 template <class T>
 void
 test()

     typedef std::hash<T> H;
     static_assert((std::is_same<typename H::argument_type, T>::value), "" );
     static_assert((std::is_same<typename H::result_type, std::size_t>::value), "" );
+    ASSERT_NOEXCEPT(H()(T()));
     H h;
 
     std::size_t t0 = h(0.);

test/std/utilities/function.objects/unord.hash/integral.pass.cpp

     typedef std::hash<T> H;
     static_assert((std::is_same<typename H::argument_type, T>::value), "" );
     static_assert((std::is_same<typename H::result_type, std::size_t>::value), "" );
+    ASSERT_NOEXCEPT(H()(T()));
     H h;
 
     for (int i = 0; i <= 5; ++i)

     test<long long>();
     test<unsigned long long>();
 
-//  LWG #2119
+//  LWG #2119
     test<std::ptrdiff_t>();
     test<size_t>();
 
-  test<int8_t>();
-  test<int16_t>();
-  test<int32_t>();
-  test<int64_t>();
+    test<int8_t>();
+    test<int16_t>();
+    test<int32_t>();
+    test<int64_t>();
 
-  test<int_fast8_t>();
-  test<int_fast16_t>();
-  test<int_fast32_t>();
-  test<int_fast64_t>();
+    test<int_fast8_t>();
+    test<int_fast16_t>();
+    test<int_fast32_t>();
+    test<int_fast64_t>();
 
-  test<int_least8_t>();
-  test<int_least16_t>();
-  test<int_least32_t>();
-  test<int_least64_t>();
+    test<int_least8_t>();
+    test<int_least16_t>();
+    test<int_least32_t>();
+    test<int_least64_t>();
 
     test<intmax_t>();
     test<intptr_t>();
 
-  test<uint8_t>();
-  test<uint16_t>();
-  test<uint32_t>();
-  test<uint64_t>();
+    test<uint8_t>();
+    test<uint16_t>();
+    test<uint32_t>();
+    test<uint64_t>();
 
-  test<uint_fast8_t>();
-  test<uint_fast16_t>();
-  test<uint_fast32_t>();
-  test<uint_fast64_t>();
+    test<uint_fast8_t>();
+    test<uint_fast16_t>();
+    test<uint_fast32_t>();
+    test<uint_fast64_t>();
 
-  test<uint_least8_t>();
-  test<uint_least16_t>();
-  test<uint_least32_t>();
-  test<uint_least64_t>();
+    test<uint_least8_t>();
+    test<uint_least16_t>();
+    test<uint_least32_t>();
+    test<uint_least64_t>();
 
     test<uintmax_t>();
     test<uintptr_t>();

test/std/utilities/function.objects/unord.hash/pointer.pass.cpp

 #include <type_traits>
 #include <limits>
 
+#include "test_macros.h"
+
 template <class T>
 void
 test()

     typedef std::hash<T> H;
     static_assert((std::is_same<typename H::argument_type, T>::value), "" );
     static_assert((std::is_same<typename H::result_type, std::size_t>::value), "" );
+    ASSERT_NOEXCEPT(H()(T()));
     H h;
 
     typedef typename std::remove_pointer<T>::type type;

     assert(h(&i) != h(&j));
 }
 
+void test_nullptr()
+{
+    typedef std::nullptr_t T;
+    typedef std::hash<T> H;
+    static_assert((std::is_same<typename H::argument_type, T>::value), "" );
+    static_assert((std::is_same<typename H::result_type, std::size_t>::value), "" );
+    ASSERT_NOEXCEPT(H()(T()));
+}
+
 int main()
 {
     test<int*>();
+    test_nullptr();
 }

test/std/utilities/template.bitset/bitset.hash/bitset.pass.cpp

     typedef std::hash<T> H;
     static_assert((std::is_same<typename H::argument_type, T>::value), "" );
     static_assert((std::is_same<typename H::result_type, std::size_t>::value), "" );
+    ASSERT_NOEXCEPT(H()(T()));
+    
     H h;
     T bs(static_cast<unsigned long long>(N));
     const std::size_t result = h(bs);

test/std/utilities/variant/variant.hash/hash.pass.cpp

   assert(h(m1) == h(m2));
   {
     ASSERT_SAME_TYPE(decltype(h(m1)), std::size_t);
+    ASSERT_NOEXCEPT(h(m1));
     static_assert(std::is_copy_constructible<H>::value, "");
   }
   {