Add noexcept to enable_shared_from_this::weak_from_this

	* include/bits/shared_ptr.h (enable_shared_from_this::weak_from_this):
	Add noexcept.
	* include/bits/shared_ptr_base.h
	(__enable_shared_from_this::weak_from_this): Likewise.
	* testsuite/20_util/enable_shared_from_this/members/weak_from_this.cc:
	Test exception-specification of weak_from_this.

From-SVN: r240917

libstdc++-v3/ChangeLog

+2016-10-10  Jonathan Wakely  <jwakely@redhat.com>
+
+	* include/bits/shared_ptr.h (enable_shared_from_this::weak_from_this):
+	Add noexcept.
+	* include/bits/shared_ptr_base.h
+	(__enable_shared_from_this::weak_from_this): Likewise.
+	* testsuite/20_util/enable_shared_from_this/members/weak_from_this.cc:
+	Test exception-specification of weak_from_this.
+
 2016-10-07  Jonathan Wakely  <jwakely@redhat.com>
 
 	* doc/xml/manual/status_cxx1998.xml: Improve documentation of

libstdc++-v3/include/bits/shared_ptr.h

@@ -593,11 +593,11 @@ _GLIBCXX_BEGIN_NAMESPACE_VERSION
 #if __cplusplus > 201402L || !defined(__STRICT_ANSI__) // c++1z or gnu++11
 #define __cpp_lib_enable_shared_from_this 201603
       weak_ptr<_Tp>
-      weak_from_this()
+      weak_from_this() noexcept
       { return this->_M_weak_this; }
 
       weak_ptr<const _Tp>
-      weak_from_this() const
+      weak_from_this() const noexcept
       { return this->_M_weak_this; }
 #endif
 

libstdc++-v3/include/bits/shared_ptr_base.h

@@ -1562,11 +1562,11 @@ _GLIBCXX_BEGIN_NAMESPACE_VERSION
 
 #if __cplusplus > 201402L || !defined(__STRICT_ANSI__) // c++1z or gnu++11
       __weak_ptr<_Tp, _Lp>
-      weak_from_this()
+      weak_from_this() noexcept
       { return this->_M_weak_this; }
 
       __weak_ptr<const _Tp, _Lp>
-      weak_from_this() const
+      weak_from_this() const noexcept
       { return this->_M_weak_this; }
 #endif
 

libstdc++-v3/testsuite/20_util/enable_shared_from_this/members/weak_from_this.cc

@@ -26,6 +26,9 @@
 
 struct X : public std::enable_shared_from_this<X> { };
 
+static_assert( noexcept(std::declval<X&>().weak_from_this()) );
+static_assert( noexcept(std::declval<const X&>().weak_from_this()) );
+
 void
 test01()
 {