decltype

README.adoc

@@ -20518,6 +20518,20 @@ link:userland/cpp/static_dynamic_reinterpret_cast.cpp[]
 
 https://stackoverflow.com/questions/332030/when-should-static-cast-dynamic-cast-const-cast-and-reinterpret-cast-be-used/60414256#60414256
 
+[[cpp-compile-time-magic]]
+==== C++ compile time magic
+
+[[cpp-decltype]]
+===== C++ `decltype`
+
+link:userland/cpp/decltype.cpp[]
+
+C++11 keyword.
+
+Replaces decltype with type of an expression at compile time.
+
+More powerful than `auto` as you can use it in more places.
+
 === POSIX
 
 Programs under link:userland/posix/[] are examples of POSIX C programming.