[atomics.syn], [atomics.flag] Clean up presentation around

ATOMIC_FLAG_INIT.

 * Add some vertical whitespace in description of atomic_flag operations.
 * Reorder ATOMIC_FLAG_INIT earlier in synopsis for consistency.
 * Add proper item description for ATOMIC_FLAG_INIT.
 * Remove repetition of declarations of atomic_flag non-member functions
   and the ATOMIC_FLAG_INIT macro from [atomics.flag].

Author: zygoloid

source/atomics.tex

@@ -56,6 +56,9 @@
   // \ref{atomics.types.pointer}, partial specialization for pointers
   template<class T> struct atomic<T*>;
 
+  // \ref{atomics.types.operations}, initialization
+  #define ATOMIC_VAR_INIT(value) @\seebelow@
+
   // \ref{atomics.nonmembers}, non-member functions
   template<class T>
     bool atomic_is_lock_free(const volatile atomic<T>*) noexcept;
@@ -200,9 +203,6 @@
   template<class T>
     void atomic_notify_all(atomic<T>*);
 
-  // \ref{atomics.types.operations}, initialization
-  #define ATOMIC_VAR_INIT(value) @\seebelow@
-
   // \ref{atomics.alias}, type aliases
   using atomic_bool           = atomic<bool>;
   using atomic_char           = atomic<char>;
@@ -260,6 +260,9 @@
 
   // \ref{atomics.flag}, flag type and operations
   struct atomic_flag;
+
+  #define ATOMIC_FLAG_INIT @\seebelow@
+
   bool atomic_flag_test(const volatile atomic_flag*) noexcept;
   bool atomic_flag_test(const atomic_flag*) noexcept;
   bool atomic_flag_test_explicit(const volatile atomic_flag*, memory_order) noexcept;
@@ -272,6 +275,7 @@
   void atomic_flag_clear(atomic_flag*) noexcept;
   void atomic_flag_clear_explicit(volatile atomic_flag*, memory_order) noexcept;
   void atomic_flag_clear_explicit(atomic_flag*, memory_order) noexcept;
+
   void atomic_flag_wait(const volatile atomic_flag*, bool) noexcept;
   void atomic_flag_wait(const atomic_flag*, bool) noexcept;
   void atomic_flag_wait_explicit(const volatile atomic_flag*,
@@ -282,7 +286,6 @@
   void atomic_flag_notify_one(atomic_flag*) noexcept;
   void atomic_flag_notify_all(volatile atomic_flag*) noexcept;
   void atomic_flag_notify_all(atomic_flag*) noexcept;
-  #define ATOMIC_FLAG_INIT @\seebelow@
 
   // \ref{atomics.fences}, fences
   extern "C" void atomic_thread_fence(memory_order) noexcept;
@@ -2628,32 +2631,6 @@
     atomic_flag& operator=(const atomic_flag&) = delete;
     atomic_flag& operator=(const atomic_flag&) volatile = delete;
   };
-
-  bool atomic_flag_test(const volatile atomic_flag*) noexcept;
-  bool atomic_flag_test(const atomic_flag*) noexcept;
-  bool atomic_flag_test_explicit(const volatile atomic_flag*, memory_order) noexcept;
-  bool atomic_flag_test_explicit(const atomic_flag*, memory_order) noexcept;
-  bool atomic_flag_test_and_set(volatile atomic_flag*) noexcept;
-  bool atomic_flag_test_and_set(atomic_flag*) noexcept;
-  bool atomic_flag_test_and_set_explicit(volatile atomic_flag*, memory_order) noexcept;
-  bool atomic_flag_test_and_set_explicit(atomic_flag*, memory_order) noexcept;
-  void atomic_flag_clear(volatile atomic_flag*) noexcept;
-  void atomic_flag_clear(atomic_flag*) noexcept;
-  void atomic_flag_clear_explicit(volatile atomic_flag*, memory_order) noexcept;
-  void atomic_flag_clear_explicit(atomic_flag*, memory_order) noexcept;
-
-  void atomic_flag_wait(const volatile atomic_flag*, bool) noexcept;
-  void atomic_flag_wait(const atomic_flag*, bool) noexcept;
-  void atomic_flag_wait_explicit(const volatile atomic_flag*,
-                                 bool, memory_order) noexcept;
-  void atomic_flag_wait_explicit(const atomic_flag*,
-                                 bool, memory_order) noexcept;
-  void atomic_flag_notify_one(volatile atomic_flag*) noexcept;
-  void atomic_flag_notify_one(atomic_flag*) noexcept;
-  void atomic_flag_notify_all(volatile atomic_flag*) noexcept;
-  void atomic_flag_notify_all(atomic_flag*) noexcept;
-
-  #define ATOMIC_FLAG_INIT @\seebelow@
 }
 \end{codeblock}
 
@@ -2668,7 +2645,14 @@
 The \tcode{atomic_flag} type is a standard-layout struct.
 It has a trivial default constructor and a trivial destructor.
 
+\indexlibrary{\idxcode{ATOMIC_FLAG_INIT}}%
+\begin{itemdecl}
+#define ATOMIC_FLAG_INIT @\seebelow@
+\end{itemdecl}
+
+\begin{itemdescr}
 \pnum
+\remarks
 The macro \tcode{ATOMIC_FLAG_INIT} shall be defined in such a way that it can be used to initialize an object of type \tcode{atomic_flag} to the
 clear state. The macro can be used in the form:
 \begin{codeblock}
@@ -2678,6 +2662,7 @@
 For a complete static-duration object, that initialization shall be static.
 Unless initialized with \tcode{ATOMIC_FLAG_INIT}, it is unspecified whether an
 \tcode{atomic_flag} object has an initial state of set or clear.
+\end{itemdescr}
 
 \indexlibrary{\idxcode{atomic_flag_test}}%
 \indexlibrary{\idxcode{atomic_flag_test_explicit}}%