libstdc++: Add comparison operators to <charconv> result types

Some more C++20 changes from P1614R2, "The Mothership has Landed".

	* include/std/charconv (to_chars_result, from_chars_result): Add
	defaulted equality comparisons for C++20.
	* testsuite/20_util/from_chars/compare.cc: New test.
	* testsuite/20_util/to_chars/compare.cc: New test.

4 files changed, 120 insertions, 1 deletions

diff --git a/libstdc++-v3/ChangeLog b/libstdc++-v3/ChangeLog
index b95a893..fddba57 100644
--- a/libstdc++-v3/ChangeLog
+++ b/libstdc++-v3/ChangeLog
@@ -1,3 +1,10 @@
+2020-04-08  Jonathan Wakely  <jwakely@redhat.com>
+
+	* include/std/charconv (to_chars_result, from_chars_result): Add
+	defaulted equality comparisons for C++20.
+	* testsuite/20_util/from_chars/compare.cc: New test.
+	* testsuite/20_util/to_chars/compare.cc: New test.
+
 2020-04-07  Jonathan Wakely  <jwakely@redhat.com>
 
 	PR libstdc++/94520
diff --git a/libstdc++-v3/include/std/charconv b/libstdc++-v3/include/std/charconv
index 8c9ce9d..3caa0f8 100644
--- a/libstdc++-v3/include/std/charconv
+++ b/libstdc++-v3/include/std/charconv
@@ -44,7 +44,8 @@
 #include <bits/error_constants.h> // for std::errc
 #include <bits/int_limits.h>
 
-// Define when floating point is supported: #define __cpp_lib_to_chars 201611L
+// FIXME: Define when floating point is supported:
+// #define __cpp_lib_to_chars 201611L
 
 namespace std _GLIBCXX_VISIBILITY(default)
 {
@@ -55,6 +56,11 @@ _GLIBCXX_BEGIN_NAMESPACE_VERSION
   {
     char* ptr;
     errc ec;
+
+#if __cplusplus > 201703L && __cpp_impl_three_way_comparison >= 201907L
+    friend bool
+    operator==(const to_chars_result&, const to_chars_result&) = default;
+#endif
   };
 
   /// Result type of std::from_chars
@@ -62,6 +68,11 @@ _GLIBCXX_BEGIN_NAMESPACE_VERSION
   {
     const char* ptr;
     errc ec;
+
+#if __cplusplus > 201703L && __cpp_impl_three_way_comparison >= 201907L
+    friend bool
+    operator==(const from_chars_result&, const from_chars_result&) = default;
+#endif
   };
 
 namespace __detail
diff --git a/libstdc++-v3/testsuite/20_util/from_chars/compare.cc b/libstdc++-v3/testsuite/20_util/from_chars/compare.cc
new file mode 100644
index 0000000..04d51af
--- /dev/null
+++ b/libstdc++-v3/testsuite/20_util/from_chars/compare.cc
@@ -0,0 +1,50 @@
+// Copyright (C) 2020 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++2a" }
+// { dg-do run { target c++2a } }
+
+#include <charconv>
+#include <testsuite_hooks.h>
+
+void
+test01()
+{
+  std::from_chars_result r1{}, r2{};
+  VERIFY( r1 == r1 );
+  VERIFY( !(r1 != r1) );
+  VERIFY( r2 == r1 );
+  VERIFY( !(r2 != r1) );
+  r1.ptr = "";
+  VERIFY( r1 == r1 );
+  VERIFY( r1 != r2 );
+  r2.ptr = "a" + 1;
+  VERIFY( r1 != r2 );
+  r2.ptr = r1.ptr;
+  r2.ec = std::errc::invalid_argument;
+  VERIFY( r1 != r2 );
+  r1.ec = std::errc::no_such_file_or_directory;
+  VERIFY( r1 != r2 );
+  r1.ec = std::errc::invalid_argument;
+  VERIFY( r2 == r1 );
+}
+
+int
+main()
+{
+  test01();
+}
diff --git a/libstdc++-v3/testsuite/20_util/to_chars/compare.cc b/libstdc++-v3/testsuite/20_util/to_chars/compare.cc
new file mode 100644
index 0000000..6423295
--- /dev/null
+++ b/libstdc++-v3/testsuite/20_util/to_chars/compare.cc
@@ -0,0 +1,51 @@
+// Copyright (C) 2020 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++2a" }
+// { dg-do run { target c++2a } }
+
+#include <charconv>
+#include <testsuite_hooks.h>
+
+void
+test01()
+{
+  char str[2]{};
+  std::to_chars_result r1{}, r2{};
+  VERIFY( r1 == r1 );
+  VERIFY( !(r1 != r1) );
+  VERIFY( r2 == r1 );
+  VERIFY( !(r2 != r1) );
+  r1.ptr = str;
+  VERIFY( r1 == r1 );
+  VERIFY( r1 != r2 );
+  r2.ptr = str + 1;
+  VERIFY( r1 != r2 );
+  r2.ptr = r1.ptr;
+  r2.ec = std::errc::invalid_argument;
+  VERIFY( r1 != r2 );
+  r1.ec = std::errc::no_such_file_or_directory;
+  VERIFY( r1 != r2 );
+  r1.ec = std::errc::invalid_argument;
+  VERIFY( r2 == r1 );
+}
+
+int
+main()
+{
+  test01();
+}