requirements: use concepts to improve requirement validation

include/boost/lockfree/lockfree_forward.hpp

@@ -11,7 +11,8 @@
 
 #ifndef BOOST_DOXYGEN_INVOKED
 
-#    include <cstddef> // size_t
+#    include <cstddef>
+#    include <type_traits>
 
 #    include <boost/config.hpp>
 
@@ -31,14 +32,24 @@ struct allocator;
 // data structures
 
 template < typename T, typename... Options >
+#    if !defined( BOOST_NO_CXX20_HDR_CONCEPTS )
+    requires( std::is_copy_assignable_v< T >,
+              std::is_trivially_assignable_v< T&, T >,
+              std::is_trivially_destructible_v< T > )
+#    endif
 class queue;
 
 template < typename T, typename... Options >
+#    if !defined( BOOST_NO_CXX20_HDR_CONCEPTS )
+    requires( std::is_copy_assignable_v< T > || std::is_move_assignable_v< T > )
+#    endif
 class stack;
 
 template < typename T, typename... Options >
+#    if !defined( BOOST_NO_CXX20_HDR_CONCEPTS )
+    requires( std::is_default_constructible_v< T >, std::is_move_assignable_v< T > || std::is_copy_assignable_v< T > )
+#    endif
 class spsc_queue;
-
 }}     // namespace boost::lockfree
 
 #endif // BOOST_DOXYGEN_INVOKED

include/boost/lockfree/queue.hpp

@@ -82,6 +82,11 @@ typedef parameter::parameters< boost::parameter::optional< tag::allocator >, boo
  *
  * */
 template < typename T, typename... Options >
+#if !defined( BOOST_NO_CXX20_HDR_CONCEPTS )
+    requires( std::is_copy_assignable_v< T >,
+              std::is_trivially_assignable_v< T&, T >,
+              std::is_trivially_destructible_v< T > )
+#endif
 class queue
 {
 private:
@@ -167,7 +172,11 @@ class queue
      *
      *  \pre Must specify a capacity<> argument
      * */
-    queue( void ) :
+    queue( void )
+#if !defined( BOOST_NO_CXX20_HDR_CONCEPTS )
+        requires( has_capacity )
+#endif
+        :
         head_( tagged_node_handle( 0, 0 ) ),
         tail_( tagged_node_handle( 0, 0 ) ),
         pool( node_allocator(), capacity )

include/boost/lockfree/spsc_queue.hpp

@@ -609,9 +609,12 @@ struct make_ringbuffer
  *
  *  \b Requirements:
  *  - T must have a default constructor
- *  - T must be copyable
+ *  - T must be copyable or movable
  * */
 template < typename T, typename... Options >
+#if !defined( BOOST_NO_CXX20_HDR_CONCEPTS )
+    requires( std::is_default_constructible_v< T >, std::is_move_assignable_v< T > || std::is_copy_assignable_v< T > )
+#endif
 class spsc_queue : public detail::make_ringbuffer< T, Options... >::ringbuffer_type
 {
 private:
@@ -637,6 +640,9 @@ class spsc_queue : public detail::make_ringbuffer< T, Options... >::ringbuffer_t
      *  \pre spsc_queue must be configured to be sized at compile-time
      */
     spsc_queue( void )
+#if !defined( BOOST_NO_CXX20_HDR_CONCEPTS )
+        requires( !runtime_sized )
+#endif
     {
         // Don't use BOOST_STATIC_ASSERT() here since it will be evaluated when compiling
         // this function and this function may be compiled even when it isn't being used.

include/boost/lockfree/stack.hpp

@@ -59,9 +59,12 @@ typedef parameter::parameters< boost::parameter::optional< tag::allocator >, boo
  *    Specifies the allocator that is used for the internal freelist
  *
  *  \b Requirements:
- *  - T must have a copy constructor
+ *  - T must have a copy constructor or a move constructor
  * */
 template < typename T, typename... Options >
+#if !defined( BOOST_NO_CXX20_HDR_CONCEPTS )
+    requires( std::is_copy_assignable_v< T > || std::is_move_assignable_v< T > )
+#endif
 class stack
 {
 private:
@@ -132,7 +135,11 @@ class stack
      *
      *  \pre Must specify a capacity<> argument
      * */
-    explicit stack( void ) :
+    explicit stack( void )
+#if !defined( BOOST_NO_CXX20_HDR_CONCEPTS )
+        requires( has_capacity )
+#endif
+        :
         pool( node_allocator(), capacity )
     {
         // Don't use BOOST_STATIC_ASSERT() here since it will be evaluated when compiling