P2996R13 Reflection for C++26

Author: Eisenwave

source/lib-intro.tex

@@ -368,6 +368,11 @@
 and also define the function as deleted.
 \end{example}
 
+\item
+\constantwhen
+the conditions that are required for a call to the function
+to be a constant subexpression\iref{defns.const.subexpr}.
+
 \item
 \expects
 conditions that the function assumes to hold whenever it is called;
@@ -454,6 +459,7 @@
 Next, the semantics of the code sequence are determined by the
 \Fundescx{Constraints},
 \Fundescx{Mandates},
+\Fundescx{Constant When},
 \Fundescx{Preconditions},
 \Fundescx{Hardened preconditions},
 \Fundescx{Effects},
@@ -1248,6 +1254,7 @@
 \tcode{<mdspan>} \\
 \tcode{<memory>} \\
 \tcode{<memory_resource>} \\
+\tcode{<meta>} \\
 \tcode{<mutex>} \\
 \columnbreak
 \tcode{<new>} \\
@@ -3082,6 +3089,26 @@
 either a standard library non-static member function\iref{member.functions}
 or an instantiation of a standard library member function template.
 
+\pnum
+Let \tcode{\placeholder{F}} denote
+a standard library function or function template.
+Unless \tcode{\placeholder{F}} is designated an addressable function,
+it is unspecified if or how
+a reflection value designating the associated entity can be formed.
+%FIXME: Why is this not an example, but a note that begins with "For example"?
+\begin{note}
+For example, it is possible that \tcode{std::meta::members_of}
+will not return reflections of standard library functions
+that an implementation handles through an extra-linguistic mechanism.
+\end{note}
+
+\pnum
+Let \tcode{\placeholder{F}} denote
+a standard library class or class template specialization.
+It is unspecified if or how
+a reflection value can be formed to any private member of \tcode{\placeholder{F}},
+or what the names of such members may be.
+
 \pnum
 A translation unit shall not declare namespace \tcode{std} to be an inline namespace\iref{namespace.def}.
 

source/macros.tex

@@ -363,6 +363,7 @@
 \newcommand{\required}{\Fundesc{Required behavior}}
 \newcommand{\constraints}{\Fundesc{Constraints}}
 \newcommand{\mandates}{\Fundesc{Mandates}}
+\newcommand{\constantwhen}{\Fundesc{Constant When}}
 \newcommand{\expects}{\Fundesc{Preconditions}}
 \newcommand{\hardexpects}{\Fundesc{Hardened preconditions}}
 \newcommand{\effects}{\Fundesc{Effects}}