LWG2783 stack::emplace() and queue::emplace() should return decltype(auto)

Author: Dawn Perchik

source/containers.tex

@@ -9285,7 +9285,8 @@
     void push(const value_type& x)      { c.push_back(x); }
     void push(value_type&& x)           { c.push_back(std::move(x)); }
     template <class... Args>
-      reference emplace(Args&&... args) { return c.emplace_back(std::forward<Args>(args)...); }
+      decltype(auto) emplace(Args&&... args)
+        { return c.emplace_back(std::forward<Args>(args)...); }
     void pop()                          { c.pop_front(); }
     void swap(queue& q) noexcept(is_nothrow_swappable_v<Container>)
       { using std::swap; swap(c, q.c); }
@@ -9841,7 +9842,8 @@
     void push(const value_type& x)      { c.push_back(x); }
     void push(value_type&& x)           { c.push_back(std::move(x)); }
     template <class... Args>
-      reference emplace(Args&&... args) { return c.emplace_back(std::forward<Args>(args)...); }
+      decltype(auto) emplace(Args&&... args)
+        { return c.emplace_back(std::forward<Args>(args)...); }
     void pop()                          { c.pop_back(); }
     void swap(stack& s) noexcept(is_nothrow_swappable_v<Container>)
       { using std::swap; swap(c, s.c); }