libstdc++: Make std::from_chars always round to nearest

[thirdparty/gcc.git] / libstdc++-v3 / testsuite / 20_util / from_chars / 6.cc

diff --git a/libstdc++-v3/testsuite/20_util/from_chars/6.cc b/libstdc++-v3/testsuite/20_util/from_chars/6.cc
new file mode 100644 (file)
index 0000000..e592b2e
--- /dev/null
+++ b/libstdc++-v3/testsuite/20_util/from_chars/6.cc
@@ -0,0 +1,49 @@
+// 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/>.
+
+// <charconv> is supported in C++14 as a GNU extension
+// { dg-do run { target c++14 } }
+// { dg-add-options ieee }
+
+#include <charconv>
+#include <string>
+#include <cfenv>
+#include <testsuite_hooks.h>
+
+void
+test01()
+{
+#if __cpp_lib_to_chars >= 201611L || _GLIBCXX_HAVE_USELOCALE
+#if _GLIBCXX_USE_C99_FENV_TR1
+  double d;
+  std::fesetround(FE_DOWNWARD);
+  const std::string s = "0.099999999999999999999999999";
+  auto res = std::from_chars(s.data(), s.data() + s.length(), d);
+  VERIFY( res.ec == std::errc{} );
+  VERIFY( res.ptr == s.data() + s.length() );
+  // std::from_chars should ignore the current rounding mode
+  // and always round to nearest.
+  VERIFY( d == 0.1 );
+#endif
+#endif
+}
+
+int
+main()
+{
+  test01();
+}