libstdc++: Implement LWG 415 for std::ws

For C++11 std::ws changed to be an unformatted input function, meaning
it constructs a sentry and sets badbit on exceptions.

libstdc++-v3/ChangeLog:

	* doc/xml/manual/intro.xml: Document LWG 415 change.
	* doc/html/manual/bugs.html: Regenerate.
	* include/bits/istream.tcc (ws): Create sentry and catch
	exceptions.
	* testsuite/27_io/basic_istream/ws/char/lwg415.cc: New test.
	* testsuite/27_io/basic_istream/ws/wchar_t/lwg415.cc: New test.

2 files changed, 154 insertions, 0 deletions

diff --git a/libstdc++-v3/testsuite/27_io/basic_istream/ws/char/lwg415.cc b/libstdc++-v3/testsuite/27_io/basic_istream/ws/char/lwg415.cc
new file mode 100644
index 0000000..fe6980d
--- /dev/null
+++ b/libstdc++-v3/testsuite/27_io/basic_istream/ws/char/lwg415.cc
@@ -0,0 +1,77 @@
+#include <istream>
+
+// C++11 27.7.2.4 Standard basic_istream manipulators [istream.manip]
+//
+// LWG 415. behavior of std::ws
+// std::ws is an unformatted input function.
+
+#include <istream>
+#include <testsuite_hooks.h>
+#include <testsuite_io.h>
+
+void
+test01()
+{
+  std::istream is(0);
+  VERIFY( is.rdstate() == std::ios_base::badbit );
+
+  is >> std::ws; // sentry should set failbit
+  VERIFY( is.rdstate() & std::ios_base::failbit );
+}
+
+void
+test02()
+{
+  __gnu_test::sync_streambuf buf;
+  std::istream is(&buf);
+
+  __gnu_test::sync_streambuf buf_tie;
+  std::ostream os_tie(&buf_tie);
+
+  // A sentry should be constructed so is.tie()->flush() should be called.
+  // The standard allows the flush to be deferred because the put area of
+  // is_tie is empty, but libstdc++ doesn't defer it.
+  is.tie(&os_tie);
+
+  is >> std::ws;
+
+  VERIFY( is.eof() );
+  VERIFY( !is.fail() );
+  VERIFY( ! buf.sync_called() );
+  VERIFY( buf_tie.sync_called() );
+}
+
+void
+test03()
+{
+  __gnu_test::fail_streambuf buf;
+  std::istream is(&buf);
+
+  char c;
+  is >> c >> std::ws;
+  VERIFY( is.rdstate() == std::ios_base::badbit );
+
+  is.clear();
+  is.exceptions(std::ios_base::badbit);
+
+  try
+  {
+    is >> std::ws;
+    VERIFY( false );
+  }
+  catch (const __gnu_test::underflow_error&)
+  {
+    VERIFY( is.rdstate() == std::ios_base::badbit );
+  }
+  catch (...)
+  {
+    VERIFY( false );
+  }
+}
+
+int main()
+{
+  test01();
+  test02();
+  test03();
+}
diff --git a/libstdc++-v3/testsuite/27_io/basic_istream/ws/wchar_t/lwg415.cc b/libstdc++-v3/testsuite/27_io/basic_istream/ws/wchar_t/lwg415.cc
new file mode 100644
index 0000000..fd04009
--- /dev/null
+++ b/libstdc++-v3/testsuite/27_io/basic_istream/ws/wchar_t/lwg415.cc
@@ -0,0 +1,77 @@
+#include <istream>
+
+// C++11 27.7.2.4 Standard basic_istream manipulators [istream.manip]
+//
+// LWG 415. behavior of std::ws
+// std::ws is an unformatted input function.
+
+#include <istream>
+#include <testsuite_hooks.h>
+#include <testsuite_io.h>
+
+void
+test01()
+{
+  std::wistream is(0);
+  VERIFY( is.rdstate() == std::ios_base::badbit );
+
+  is >> std::ws; // sentry should set failbit
+  VERIFY( is.rdstate() & std::ios_base::failbit );
+}
+
+void
+test02()
+{
+  __gnu_test::sync_wstreambuf buf;
+  std::wistream is(&buf);
+
+  __gnu_test::sync_wstreambuf buf_tie;
+  std::wostream os_tie(&buf_tie);
+
+  // A sentry should be constructed so is.tie()->flush() should be called.
+  // The standard allows the flush to be deferred because the put area of
+  // is_tie is empty, but libstdc++ doesn't defer it.
+  is.tie(&os_tie);
+
+  is >> std::ws;
+
+  VERIFY( is.eof() );
+  VERIFY( !is.fail() );
+  VERIFY( ! buf.sync_called() );
+  VERIFY( buf_tie.sync_called() );
+}
+
+void
+test03()
+{
+  __gnu_test::fail_wstreambuf buf;
+  std::wistream is(&buf);
+
+  wchar_t c;
+  is >> c >> std::ws;
+  VERIFY( is.rdstate() == std::ios_base::badbit );
+
+  is.clear();
+  is.exceptions(std::ios_base::badbit);
+
+  try
+  {
+    is >> std::ws;
+    VERIFY( false );
+  }
+  catch (const __gnu_test::underflow_error&)
+  {
+    VERIFY( is.rdstate() == std::ios_base::badbit );
+  }
+  catch (...)
+  {
+    VERIFY( false );
+  }
+}
+
+int main()
+{
+  test01();
+  test02();
+  test03();
+}