LWG4172 unique_lock self-move-assignment is broken

Change suggested on the LWG reflector: Use parens instead of braced-init.

Author: burblebee

source/threads.tex

@@ -7634,7 +7634,7 @@
     unique_lock& operator=(const unique_lock&) = delete;
 
     unique_lock(unique_lock&& u) noexcept;
-    unique_lock& operator=(unique_lock&& u);
+    unique_lock& operator=(unique_lock&& u) noexcept;
 
     // \ref{thread.lock.unique.locking}, locking
     void lock();
@@ -7821,26 +7821,17 @@
 
 \indexlibrarymember{operator=}{unique_lock}%
 \begin{itemdecl}
-unique_lock& operator=(unique_lock&& u);
+unique_lock& operator=(unique_lock&& u) noexcept;
 \end{itemdecl}
 
 \begin{itemdescr}
 \pnum
 \effects
-If \tcode{owns} calls \tcode{pm->unlock()}.
-
-\pnum
-\ensures
-\tcode{pm == u_p.pm} and \tcode{owns == u_p.owns} (where \tcode{u_p} is the state of \tcode{u} just prior to this construction),  \tcode{u.pm == 0} and \tcode{u.owns == false}.
+Equivalent to: \tcode{unique_lock(std::move(u)).swap(*this)}
 
 \pnum
-\begin{note}
-With a recursive mutex it is possible for both \tcode{*this} and \tcode{u} to own the same mutex before the assignment. In this case, \tcode{*this} will own the mutex after the assignment and \tcode{u} will not.
-\end{note}
-
-\pnum
-\throws
-Nothing.
+\returns
+\tcode{*this}.
 \end{itemdescr}
 
 \indexlibrarydtor{unique_lock}%
@@ -8327,13 +8318,11 @@
 \begin{itemdescr}
 \pnum
 \effects
-If \tcode{owns} calls \tcode{pm->unlock_shared()}.
+Equivalent to: \tcode{shared_lock(std::move(sl)).swap(*this)}
 
 \pnum
-\ensures
-\tcode{pm == sl_p.pm} and \tcode{owns == sl_p.owns} (where
-\tcode{sl_p} is the state of \tcode{sl} just prior to this assignment),
-\tcode{sl.pm == nullptr} and \tcode{sl.owns == false}.
+\returns
+\tcode{*this}.
 \end{itemdescr}
 
 \rSec4[thread.lock.shared.locking]{Locking}