P3533R2 constexpr virtual inheritance

Fixes #7936
Fixes cplusplus/papers#2174

Author: AlisdairM

source/declarations.tex

@@ -916,14 +916,8 @@
 \indextext{specifier!\idxcode{constexpr}!function}%
 \indextext{constexpr function}%
 A function is \defn{constexpr-suitable} if
-\begin{itemize}
-\item
-it is not a coroutine\iref{dcl.fct.def.coroutine}, and
+it is not a coroutine\iref{dcl.fct.def.coroutine}.
 
-\item
-if the function is a constructor or destructor,
-its class does not have any virtual base classes.
-\end{itemize}
 Except for instantiated constexpr functions,
 non-templated constexpr functions shall be constexpr-suitable.
 

source/preprocessor.tex

@@ -2301,6 +2301,7 @@
 \defnxname{cpp_constexpr_dynamic_alloc}           & \tcode{201907L} \\ \rowsep
 \defnxname{cpp_constexpr_exceptions}              & \tcode{202411L} \\ \rowsep
 \defnxname{cpp_constexpr_in_decltype}             & \tcode{201711L} \\ \rowsep
+\defnxname{cpp_constexpr_virtual_inheritance}     & \tcode{202506L} \\ \rowsep
 \defnxname{cpp_consteval}                         & \tcode{202211L} \\ \rowsep
 \defnxname{cpp_constinit}                         & \tcode{201907L} \\ \rowsep
 \defnxname{cpp_contracts}                         & \tcode{202502L} \\ \rowsep