PR libstdc++/60966

	* include/std/future (__future_base::_State_baseV2::_M_set_result):
	Signal condition variable after call_once returns.
	(__future_base::_State_baseV2::_M_do_set): Do not signal here.
	(promise::set_value, promise::set_exception): Increment the reference
	count on the shared state until the function returns.
	* testsuite/30_threads/promise/60966.cc: New.

git-svn-id: svn+ssh://gcc.gnu.org/svn/gcc/branches/gcc-4_9-branch@210557 138bc75d-0d04-0410-961f-82ee72b054a4

1 files changed, 19 insertions, 10 deletions

diff --git a/libstdc++-v3/include/std/future b/libstdc++-v3/include/std/future
index 717ce7105df..998e90a9856 100644
--- a/libstdc++-v3/include/std/future
+++ b/libstdc++-v3/include/std/future
@@ -365,12 +365,14 @@ _GLIBCXX_BEGIN_NAMESPACE_VERSION
       void
       _M_set_result(function<_Ptr_type()> __res, bool __ignore_failure = false)
       {
-        bool __set = __ignore_failure;
+        bool __set = false;
         // all calls to this function are serialized,
         // side-effects of invoking __res only happen once
         call_once(_M_once, &_State_baseV2::_M_do_set, this, ref(__res),
             ref(__set));
-        if (!__set)
+	if (__set)
+	  _M_cond.notify_all();
+	else if (!__ignore_failure)
           __throw_future_error(int(future_errc::promise_already_satisfied));
       }
 
@@ -485,7 +487,6 @@ _GLIBCXX_BEGIN_NAMESPACE_VERSION
           lock_guard<mutex> __lock(_M_mutex);
           _M_result.swap(__res);
         }
-        _M_cond.notify_all();
         __set = true;
       }
 
@@ -495,6 +496,7 @@ _GLIBCXX_BEGIN_NAMESPACE_VERSION
       virtual void _M_complete_async() { }
 
       // Return true if state contains a deferred function.
+      // Caller must own _M_mutex.
       virtual bool _M_has_deferred() const { return false; }
     };
 
@@ -1007,22 +1009,25 @@ _GLIBCXX_BEGIN_NAMESPACE_VERSION
       void
       set_value(const _Res& __r)
       {
+	auto __future = _M_future;
         auto __setter = _State::__setter(this, __r);
-        _M_future->_M_set_result(std::move(__setter));
+        __future->_M_set_result(std::move(__setter));
       }
 
       void
       set_value(_Res&& __r)
       {
+	auto __future = _M_future;
         auto __setter = _State::__setter(this, std::move(__r));
-        _M_future->_M_set_result(std::move(__setter));
+        __future->_M_set_result(std::move(__setter));
       }
 
       void
       set_exception(exception_ptr __p)
       {
+	auto __future = _M_future;
         auto __setter = _State::__setter(__p, this);
-        _M_future->_M_set_result(std::move(__setter));
+        __future->_M_set_result(std::move(__setter));
       }
     };
 
@@ -1105,15 +1110,17 @@ _GLIBCXX_BEGIN_NAMESPACE_VERSION
       void
       set_value(_Res& __r)
       {
+	auto __future = _M_future;
         auto __setter = _State::__setter(this, __r);
-        _M_future->_M_set_result(std::move(__setter));
+        __future->_M_set_result(std::move(__setter));
       }
 
       void
       set_exception(exception_ptr __p)
       {
+	auto __future = _M_future;
         auto __setter = _State::__setter(__p, this);
-        _M_future->_M_set_result(std::move(__setter));
+        __future->_M_set_result(std::move(__setter));
       }
     };
 
@@ -1190,8 +1197,9 @@ _GLIBCXX_BEGIN_NAMESPACE_VERSION
       void
       set_exception(exception_ptr __p)
       {
+	auto __future = _M_future;
         auto __setter = _State::__setter(__p, this);
-        _M_future->_M_set_result(std::move(__setter));
+        __future->_M_set_result(std::move(__setter));
       }
     };
 
@@ -1217,8 +1225,9 @@ _GLIBCXX_BEGIN_NAMESPACE_VERSION
   inline void
   promise<void>::set_value()
   {
+    auto __future = _M_future;
     auto __setter = _State::__setter(this);
-    _M_future->_M_set_result(std::move(__setter));
+    __future->_M_set_result(std::move(__setter));
   }