P3914R0: Re NB US 130-193 (C++26 CD)

Fixes NB US 130-193 (C++26 CD).

Author: eisenwave

source/meta.tex

@@ -6870,6 +6870,41 @@
 consteval info @\libglobal{unwrap_ref_decay}@(info type);
 \end{codeblock}
 
+\pnum
+For a function or function template $F$ defined in this subclause,
+let $C$ be its associated class template.
+For the evaluation of a call to $F$,
+let $S$ be the specialization of $C$ in terms of which the call is specified.
+\begin{itemize}
+\item
+  If
+  \begin{itemize}
+  \item
+    the template arguments of $S$ violate a condition specified
+    in a \Fundescx{Mandates} element in the specification of $C$;
+  \item
+    the call is specified to produce a reflection of a type,
+    but $S$ would have no member named \tcode{type}; or
+  \item
+    the call is specified to return \tcode{$S$::value},
+    but that expression would not be a valid converted constant expression of type \tcode{R},
+    where \tcode{R} is the return type of $F$;
+  \end{itemize}
+  then an exception of type \tcode{meta::exception} is thrown.
+  \begin{note}
+  For the first case, $S$ is not instantiated.
+  \end{note}
+  \item
+    Otherwise, if the instantiation of $S$ would result in undefined behavior
+    due to dependence on an incomplete type\iref{meta.rqmts},
+    then the call is not a constant subexpression.
+  \item
+    Otherwise, if the template arguments of $S$ do not meet the preconditions of $C$,
+    then it is unspecified whether the call is a constant subexpression.
+    If it is, the call produces the result
+    that would be produced if $C$ had no preconditions.
+\end{itemize}
+
 \pnum
 Each function or function template declared above has the following behavior
 based on the signature and return type of that function or function template.
@@ -6888,28 +6923,28 @@
 
 \tcode{bool meta::\placeholder{UNARY}(info type);\br
 bool meta::\placeholder{UNARY}_type(info type);}  &
-\tcode{std::\placeholder{UNARY}_v<$T$>},
+\tcode{std::\placeholder{UNARY}<$T$>::value},
 where $T$ is the type or type alias represented by \tcode{type}
 \\  \rowsep
 
 \tcode{bool meta::\placeholder{BINARY}(info t1, info t2);\br
 bool meta::\placeholder{BINARY}_type(info t1, info t2);}  &
-\tcode{std::\placeholder{BINARY}_v<$T_1$, $T_2$>},
+\tcode{std::\placeholder{BINARY}<$T_1$, $T_2$>::value},
 where $T_1$ and $T_2$ are the types or type aliases
 represented by \tcode{t1} and \tcode{t2}, respectively
 \\  \rowsep
 
 \tcode{template<reflection_range R>\br
   bool meta::\placeholder{VARIADIC}_type(info type, R\&\& args);}  &
-\tcode{std::\placeholder{VARIADIC}_v<$T$, $U$...>},
+\tcode{std::\placeholder{VARIADIC}<$T$, $U$...>::value},
 where $T$ is the type or type alias represented by \tcode{type}
 and \tcode{U...} is the pack of types or type aliases
 whose elements are represented by the corresponding elements of \tcode{args}
 \\  \rowsep
 
 \tcode{template<reflection_range R>\br
   bool meta::\placeholder{VARIADIC}_type(info t1, info t2, R\&\& args);}  &
-\tcode{std::\placeholder{VARIADIC}_v<$T_1$, $T_2$, $U$...>},
+\tcode{std::\placeholder{VARIADIC}<$T_1$, $T_2$, $U$...>::value},
 where $T_1$ and $T_2$ are the types or type aliases
 represented by \tcode{t1} and \tcode{t2}, respectively,
 and \tcode{$U$...} is the pack of types or type aliases
@@ -6918,22 +6953,22 @@
 
 \tcode{info meta::\placeholder{UNARY}(info type);}  &
 A reflection representing the type denoted by
-\tcode{std::\placeholder{UNARY}_t<\brk{}$T$>},
+\tcode{std::\placeholder{UNARY}<\brk{}$T$>::type},
 where $T$ is the type or type alias represented by \tcode{type}
 \\  \rowsep
 
 \tcode{template<reflection_range R>\br
   info meta::\placeholder{VARIADIC}(R\&\& args);}  &
 A reflection representing the type denoted by
-\tcode{std::\placeholder{VARIADIC}_t<$T$...>},
+\tcode{std::\placeholder{VARIADIC}<$T$...>::type},
 where \tcode{$T$...} is the pack of types or type aliases
 whose elements are represented by the corresponding elements of \tcode{args}
 \\  \rowsep
 
 \tcode{template<reflection_range R>\br
   info meta::\placeholder{VARIADIC}(info type, R\&\& args);}  &
 A reflection representing the type denoted by
-\tcode{std::\placeholder{VARIADIC}_t<$T$, $U$...>},
+\tcode{std::\placeholder{VARIADIC}<$T$, $U$...>::type},
 where \tcode{$T$} is the type or type alias represented by \tcode{type}
 and \tcode{$U$...} is the pack of types or type aliases
 whose elements are represented by the corresponding elements of \tcode{args}
@@ -6963,7 +6998,7 @@
 \begin{itemdescr}
 \pnum
 \returns
-\tcode{rank_v<$T$>},
+\tcode{std::rank<$T$>::value},
 where $T$ is the type represented by \tcode{dealias(type)}.
 \end{itemdescr}
 
@@ -6975,7 +7010,7 @@
 \begin{itemdescr}
 \pnum
 \returns
-\tcode{extent_v<$T$, $I$>},
+\tcode{std::extent<$T$, $I$>::value},
 where $T$ is the type represented by \tcode{dealias(type)}
 and $I$ is a constant equal to \tcode{i}.
 \end{itemdescr}
@@ -6988,7 +7023,7 @@
 \begin{itemdescr}
 \pnum
 \returns
-\tcode{tuple_size_v<$T$>},
+\tcode{std::tuple_size<$T$>::value},
 where $T$ is the type represented by \tcode{dealias(type)}.
 \end{itemdescr}
 
@@ -7001,7 +7036,7 @@
 \pnum
 \returns
 A reflection representing
-the type denoted by \tcode{tuple_element_t<$I$, $T$>},
+the type denoted by \tcode{std::tuple_element<$I$, $T$>::type},
 where $T$ is the type represented by \tcode{dealias(type)}
 and $I$ is a constant equal to \tcode{index}.
 \end{itemdescr}
@@ -7014,7 +7049,7 @@
 \begin{itemdescr}
 \pnum
 \returns
-\tcode{variant_size_v<$T$>},
+\tcode{std::variant_size<$T$>::value},
 where $T$ is the type represented by \tcode{dealias(type)}.
 \end{itemdescr}
 
@@ -7027,7 +7062,7 @@
 \pnum
 \returns
 A reflection representing the type denoted by
-\tcode{variant_alternative_t<$I$, $T$>},
+\tcode{std::variant_alternative<$I$, $T$>::type},
 where $T$ is the type represented by \tcode{dealias(type)}
 and $I$ is a constant equal to \tcode{index}.
 \end{itemdescr}
@@ -7040,9 +7075,9 @@
 \begin{itemdescr}
 \pnum
 \returns
-\tcode{type_order_v<$T_1$, $T_2$>},
+\tcode{std::type_order<$T_1$, $T_2$>::value},
 where $T_1$ and $T_2$ are the types
-represented by \tcode{dealias(t1)} and \tcode{dealias(t2)}, respectively.
+represented by \tcode{de\-alias(\brk{}t1)} and \tcode{dealias(t2)}, respectively.
 \end{itemdescr}
 
 \rSec1[ratio]{Compile-time rational arithmetic}