re PR libstdc++/64650 (std::experimental::bad_optional_access is not default constructible)

	PR libstdc++/64650
	* include/experimental/optional (bad_optional_access): Add default
	constructor.
	* testsuite/experimental/optional/requirements.cc: Test for default
	constructor.

From-SVN: r219889

libstdc++-v3/ChangeLog

 2015-01-20  Jonathan Wakely  <jwakely@redhat.com>
 
+	PR libstdc++/64650
+	* include/experimental/optional (bad_optional_access): Add default
+	constructor.
+	* testsuite/experimental/optional/requirements.cc: Test for default
+	constructor.
+
+2015-01-20  Jonathan Wakely  <jwakely@redhat.com>
+
 	* include/bits/stl_map.h (map::find<>, map::count<>,
 	map::lower_bound<>, map::upper_bound<>, map::equal_range<>): New
 	member function templates to perform heterogeneous lookup.

libstdc++-v3/include/experimental/optional

@@ -110,9 +110,9 @@ _GLIBCXX_BEGIN_NAMESPACE_VERSION
   class bad_optional_access : public logic_error
   {
   public:
-    // XXX Should not be inline
-    explicit bad_optional_access(const string& __arg) : logic_error(__arg) { }
+    bad_optional_access() : logic_error("bad optional access") { }
 
+    // XXX This constructor is non-standard. Should not be inline
     explicit bad_optional_access(const char* __arg) : logic_error(__arg) { }
 
     virtual ~bad_optional_access() noexcept = default;

libstdc++-v3/testsuite/experimental/optional/requirements.cc

@@ -23,6 +23,9 @@
 
 #include <tuple>
 
+using std::experimental::bad_optional_access;
+static_assert( std::is_default_constructible<bad_optional_access>::value, "" );
+
 struct trivially_destructible
 {
   trivially_destructible() = delete;