+2013-02-04 François Dumont <fdumont@gcc.gnu.org>
+
+ * include/bits/functional_hash.h (std::__is_fast_hash<>): New.
+ * include/bits/basic_string.h: Specialize previous to mark
+ std::hash for string types as slow.
+ * include/bits/hashtable.h (__cache_default): Replace is_integral
+ with __is_fast_hash.
+ * src/c++11/hash_c++0x.cc: Add type_traits include.
+ * testsuite/23_containers/unordered_set/instantiation_neg.cc:
+ Adapt dg-error line number.
+ * testsuite/23_containers/unordered_set/
+ not_default_constructible_hash_neg.cc: Likewise.
+
2013-02-04 Manuel López-Ibáñez <manu@gcc.gnu.org>
Paolo Carlini <paolo.carlini@oracle.com>
{ return std::_Hash_impl::hash(__s.data(), __s.length()); }
};
+ template<>
+ struct __is_fast_hash<hash<string>> : std::false_type
+ { };
+
#ifdef _GLIBCXX_USE_WCHAR_T
/// std::hash specialization for wstring.
template<>
{ return std::_Hash_impl::hash(__s.data(),
__s.length() * sizeof(wchar_t)); }
};
+
+ template<>
+ struct __is_fast_hash<hash<wstring>> : std::false_type
+ { };
#endif
#endif /* _GLIBCXX_COMPATIBILITY_CXX0X */
__s.length() * sizeof(char16_t)); }
};
+ template<>
+ struct __is_fast_hash<hash<u16string>> : std::false_type
+ { };
+
/// std::hash specialization for u32string.
template<>
struct hash<u32string>
{ return std::_Hash_impl::hash(__s.data(),
__s.length() * sizeof(char32_t)); }
};
+
+ template<>
+ struct __is_fast_hash<hash<u32string>> : std::false_type
+ { };
#endif
_GLIBCXX_END_NAMESPACE_VERSION
// @} group hashes
+ // Hint about performance of hash functor. If not fast the hash based
+ // containers will cache the hash code.
+ // Default behavior is to consider that hasher are fast unless specified
+ // otherwise.
+ template<typename _Hash>
+ struct __is_fast_hash : public std::true_type
+ { };
+
+ template<>
+ struct __is_fast_hash<hash<long double>> : public std::false_type
+ { };
+
_GLIBCXX_END_NAMESPACE_VERSION
} // namespace
template<typename _Tp, typename _Hash>
using __cache_default
- = __not_<__and_<// Do not cache for builtin integral types having trivial
- // hasher.
- is_integral<_Tp>,
+ = __not_<__and_<// Do not cache for fast hasher.
+ __is_fast_hash<_Hash>,
// Mandatory to make local_iterator default
// constructible.
is_default_constructible<_Hash>,
# error "hash_c++0x.cc must be compiled with -std=gnu++0x"
#endif
+#include <type_traits>
#include <bits/functional_hash.h>
namespace std _GLIBCXX_VISIBILITY(default)
// with this library; see the file COPYING3. If not see
// <http://www.gnu.org/licenses/>.
-// { dg-error "with noexcept" "" { target *-*-* } 252 }
+// { dg-error "with noexcept" "" { target *-*-* } 251 }
#include <unordered_set>
// with this library; see the file COPYING3. If not see
// <http://www.gnu.org/licenses/>.
-// { dg-error "default constructible" "" { target *-*-* } 268 }
+// { dg-error "default constructible" "" { target *-*-* } 267 }
#include <unordered_set>