[async.reqmts.executor] Move defer requirements to new row

Fixes NB US-10 (PDTS)

Author: jwakely

src/async.tex

@@ -280,11 +280,15 @@
 \effects Creates an object \tcode{f1} initialized with \tcode{\placeholdernc{DECAY_COPY}(std::forward<Func>(f))} (\CppXref{thread.decaycopy}) in the current thread of execution. Calls \tcode{f1()} at most once. The executor may block forward progress of the caller until \tcode{f1()} finishes execution. Executor implementations should use the supplied allocator to allocate any memory required to store the function object. Prior to invoking the function object, the executor shall deallocate any memory allocated. \begin{note} Executors defined in this Technical Specification always use the supplied allocator unless otherwise specified. \end{note} \br
 \sync The invocation of \tcode{dispatch} synchronizes with (\CppXref{intro.multithread}) the invocation of \tcode{f1}.  \\ \rowsep
 
-\tcode{x1.post(std::move(f),~a)}\br
+\tcode{x1.post(std::move(f),~a)}  &
+  &
+\effects Creates an object \tcode{f1} initialized with \tcode{\placeholdernc{DECAY_COPY}(std::forward<Func>(f))} in the current thread of execution. Calls \tcode{f1()} at most once. The executor shall not block forward progress of the caller pending completion of \tcode{f1()}. The executor may begin \tcode{f1}'s progress before the call to \tcode{post} completes. Executor implementations should use the supplied allocator to allocate any memory required to store the function object. Prior to invoking the function object, the executor shall deallocate any memory allocated. \begin{note} Executors defined in this Technical Specification always use the supplied allocator unless otherwise specified. \end{note}\br
+\sync The invocation of \tcode{post} synchronizes with (\CppXref{intro.multithread}) the invocation of \tcode{f1}.  \\ \rowsep
+
 \tcode{x1.defer(std::move(f),~a)}  &
   &
-\effects Creates an object \tcode{f1} initialized with \tcode{\placeholdernc{DECAY_COPY}(std::forward<Func>(f))} in the current thread of execution. Calls \tcode{f1()} at most once. The executor shall not block forward progress of the caller pending completion of \tcode{f1()}. Executor implementations should use the supplied allocator to allocate any memory required to store the function object. Prior to invoking the function object, the executor shall deallocate any memory allocated. \begin{note} Executors defined in this Technical Specification always use the supplied allocator unless otherwise specified. \end{note}\br
-\sync The invocation of \tcode{post} or \tcode{defer} synchronizes with (\CppXref{intro.multithread}) the invocation of \tcode{f1}. \begin{note} Although the requirements placed on \tcode{defer} are identical to \tcode{post}, the use of \tcode{post} conveys a preference that the caller does not block the first step of \tcode{f1}'s progress, whereas \tcode{defer} conveys a preference that the caller does block the first step of \tcode{f1}. One use of \tcode{defer} is to convey the intention of the caller that \tcode{f1} is a continuation of the current call context. The executor may use this information to optimize or otherwise adjust the way in which \tcode{f1} is invoked. \end{note}  \\
+\effects Creates an object \tcode{f1} initialized with \tcode{\placeholdernc{DECAY_COPY}(std::forward<Func>(f))} in the current thread of execution. Calls \tcode{f1()} at most once. The executor shall not block forward progress of the caller pending completion of \tcode{f1()}. The executor should not begin \tcode{f1}'s progress before the call to \tcode{defer} completes. \begin{note} One use of \tcode{defer} is to convey the intention of the caller that \tcode{f1} is a continuation of the current call context. The executor may use this information to optimize or otherwise adjust the way in which \tcode{f1} is invoked. \end{note}  Executor implementations should use the supplied allocator to allocate any memory required to store the function object. Prior to invoking the function object, the executor shall deallocate any memory allocated. \begin{note} Executors defined in this Technical Specification always use the supplied allocator unless otherwise specified. \end{note}\br
+\sync The invocation of \tcode{defer} synchronizes with (\CppXref{intro.multithread}) the invocation of \tcode{f1}.  \\
 
 \end{libreqtab3}