Merge 2023-02 LWG Motion 14

P2674R1 A trait for implicit lifetime types

Author: tkoeppe

source/meta.tex

@@ -245,6 +245,8 @@
 
   template<class T> struct is_nothrow_destructible;
 
+  template<class T> struct is_implicit_lifetime;
+
   template<class T> struct has_virtual_destructor;
 
   template<class T> struct has_unique_object_representations;
@@ -519,6 +521,8 @@
     constexpr bool @\libglobal{is_nothrow_swappable_v}@ = is_nothrow_swappable<T>::value;
   template<class T>
     constexpr bool @\libglobal{is_nothrow_destructible_v}@ = is_nothrow_destructible<T>::value;
+  template<class T>
+    constexpr bool @\libglobal{is_implicit_lifetime_v}@ = is_implicit_lifetime<T>::value;
   template<class T>
     constexpr bool @\libglobal{has_virtual_destructor_v}@ = has_virtual_destructor<T>::value;
   template<class T>
@@ -1199,6 +1203,13 @@
   \cv{}~\keyword{void}, or an array of unknown
   bound.                \\ \rowsep
 
+\indexlibraryglobal{is_implicit_lifetime}%
+\tcode{template<class T>}\br
+  \tcode{struct is_implicit_lifetime;} &
+  \tcode{T} is an implicit-lifetime type\iref{basic.types.general}. &
+  \tcode{T} shall be an array type,
+  a complete type, or \cv{}~\keyword{void}.  \\ \rowsep
+
 \indexlibraryglobal{has_virtual_destructor}%
 \tcode{template<class T>}\br
  \tcode{struct has_virtual_destructor;} &

source/support.tex

@@ -647,6 +647,7 @@
 #define @\defnlibxname{cpp_lib_is_aggregate}@                      201703L // also in \libheader{type_traits}
 #define @\defnlibxname{cpp_lib_is_constant_evaluated}@             201811L // also in \libheader{type_traits}
 #define @\defnlibxname{cpp_lib_is_final}@                          201402L // also in \libheader{type_traits}
+#define @\defnlibxname{cpp_lib_is_implicit_lifetime}@              202302L // also in \libheader{type_traits}
 #define @\defnlibxname{cpp_lib_is_invocable}@                      201703L // also in \libheader{type_traits}
 #define @\defnlibxname{cpp_lib_is_layout_compatible}@              201907L // also in \libheader{type_traits}
 #define @\defnlibxname{cpp_lib_is_nothrow_convertible}@            201806L // also in \libheader{type_traits}