Fix std::hash<std::error_condition>

The hash value should be based on the identity (i.e. address) of the
error_category member, not its object representation (i.e. underlying
bytes).

	* include/std/system_error (error_code): Remove friend declaration
	for hash<error_code>.
	(hash<error_code>::operator()): Use public member functions to access
	value and category.
	(hash<error_condition>::operator()): Use address of category, not
	its object representation.
	* src/c++11/compatibility-c++0x.cc (hash<error_code>::operator()):
	Use public member functions to access value and category.
	* testsuite/19_diagnostics/error_condition/hash.cc: New test.

From-SVN: r270872

4 files changed, 69 insertions, 8 deletions

diff --git a/libstdc++-v3/ChangeLog b/libstdc++-v3/ChangeLog
index c434fbc..9965009 100644
--- a/libstdc++-v3/ChangeLog
+++ b/libstdc++-v3/ChangeLog
@@ -1,3 +1,15 @@
+2019-05-04  Jonathan Wakely  <jwakely@redhat.com>
+
+	* include/std/system_error (error_code): Remove friend declaration
+	for hash<error_code>.
+	(hash<error_code>::operator()): Use public member functions to access
+	value and category.
+	(hash<error_condition>::operator()): Use address of category, not
+	its object representation.
+	* src/c++11/compatibility-c++0x.cc (hash<error_code>::operator()):
+	Use public member functions to access value and category.
+	* testsuite/19_diagnostics/error_condition/hash.cc: New test.
+
 2019-05-04  François Dumont  <fdumont@gcc.gnu.org>
 
 	PR libstdc++/90277
diff --git a/libstdc++-v3/include/std/system_error b/libstdc++-v3/include/std/system_error
index b7891cb..a60c96a 100644
--- a/libstdc++-v3/include/std/system_error
+++ b/libstdc++-v3/include/std/system_error
@@ -193,8 +193,6 @@ _GLIBCXX_BEGIN_NAMESPACE_VERSION
 
     // DR 804.
   private:
-    friend class hash<error_code>;
-
     int            		_M_value;
     const error_category* 	_M_cat;
   };
@@ -394,13 +392,13 @@ _GLIBCXX_BEGIN_NAMESPACE_VERSION
       size_t
       operator()(const error_code& __e) const noexcept
       {
-	const size_t __tmp = std::_Hash_impl::hash(__e._M_value);
-	return std::_Hash_impl::__hash_combine(__e._M_cat, __tmp);
+	const size_t __tmp = std::_Hash_impl::hash(__e.value());
+	return std::_Hash_impl::__hash_combine(&__e.category(), __tmp);
       }
     };
 #endif // _GLIBCXX_COMPATIBILITY_CXX0X
 
-#if __cplusplus > 201402L
+#if __cplusplus >= 201703L
   // DR 2686.
   /// std::hash specialization for error_condition.
   template<>
@@ -411,7 +409,7 @@ _GLIBCXX_BEGIN_NAMESPACE_VERSION
       operator()(const error_condition& __e) const noexcept
       {
 	const size_t __tmp = std::_Hash_impl::hash(__e.value());
-	return std::_Hash_impl::__hash_combine(__e.category(), __tmp);
+	return std::_Hash_impl::__hash_combine(&__e.category(), __tmp);
       }
     };
 #endif
diff --git a/libstdc++-v3/src/c++11/compatibility-c++0x.cc b/libstdc++-v3/src/c++11/compatibility-c++0x.cc
index d57fdd2..25ebe43 100644
--- a/libstdc++-v3/src/c++11/compatibility-c++0x.cc
+++ b/libstdc++-v3/src/c++11/compatibility-c++0x.cc
@@ -117,8 +117,8 @@ _GLIBCXX_BEGIN_NAMESPACE_VERSION
   size_t
   hash<error_code>::operator()(error_code __e) const
   {
-    const size_t __tmp = std::_Hash_impl::hash(__e._M_value);
-    return std::_Hash_impl::__hash_combine(__e._M_cat, __tmp);
+    const size_t __tmp = std::_Hash_impl::hash(__e.value());
+    return std::_Hash_impl::__hash_combine(&__e.category(), __tmp);
   }
 
   // gcc-4.7.0
diff --git a/libstdc++-v3/testsuite/19_diagnostics/error_condition/hash.cc b/libstdc++-v3/testsuite/19_diagnostics/error_condition/hash.cc
new file mode 100644
index 0000000..3bc0561
--- /dev/null
+++ b/libstdc++-v3/testsuite/19_diagnostics/error_condition/hash.cc
@@ -0,0 +1,51 @@
+// Copyright (C) 2019 Free Software Foundation, Inc.
+//
+// This file is part of the GNU ISO C++ Library.  This library is free
+// software; you can redistribute it and/or modify it under the
+// terms of the GNU General Public License as published by the
+// Free Software Foundation; either version 3, or (at your option)
+// any later version.
+
+// This library is distributed in the hope that it will be useful,
+// but WITHOUT ANY WARRANTY; without even the implied warranty of
+// MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+// GNU General Public License for more details.
+
+// You should have received a copy of the GNU General Public License along
+// with this library; see the file COPYING3.  If not see
+// <http://www.gnu.org/licenses/>.
+
+// { dg-options "-std=gnu++17" }
+// { dg-do run { target c++17 } }
+
+#include <system_error>
+#include <testsuite_hooks.h>
+
+struct error_cat : std::error_category
+{
+  error_cat(std::string s) : _name(s) { }
+  std::string _name;
+  const char* name() const noexcept override { return _name.c_str(); }
+  std::string message(int) const override { return "error"; }
+};
+
+void
+test01()
+{
+  std::hash<std::error_condition> h;
+  error_cat kitty("kitty"), moggy("moggy");
+  std::error_condition cond1(99, kitty);
+  VERIFY( h(cond1) == h(cond1) );
+  std::error_condition cond2(99, kitty);
+  VERIFY( h(cond1) == h(cond2) );
+  std::error_condition cond3(88, kitty);
+  VERIFY( h(cond1) != h(cond3) );
+  std::error_condition cond4(99, moggy);
+  VERIFY( h(cond1) != h(cond4) );
+}
+
+int
+main()
+{
+  test01();
+}