[class.virtual] Explicit object member functions cannot be virtual

including when overriding a virtual function.
Remove a prohibition focusing on 'declared virtual'
from [dcl.fct].

Author: jensmaurer

source/classes.tex

@@ -3870,6 +3870,21 @@
 \end{codeblock}
 \end{example}
 
+\pnum
+A virtual function shall not be an explicit object member
+function\iref{dcl.fct}.
+\begin{example}
+\begin{codeblock}
+struct B {
+  virtual void g();             // \#1
+};
+struct D : B {
+  virtual void f(this D&);      // error: explicit object member function cannot be virtual
+  void g(this D&);              // overrides \#1; error: explicit object member function cannot be virtual
+};
+\end{codeblock}
+\end{example}
+
 \pnum
 The \grammarterm{ref-qualifier}, or lack thereof, of an overriding function
 shall be the same as that of the overridden function.

source/declarations.tex

@@ -3579,7 +3579,7 @@
 A \grammarterm{member-declarator} with an explicit-object-parameter-declaration
 shall not include
 a \grammarterm{ref-qualifier} or a \grammarterm{cv-qualifier-seq} and
-shall not be declared \keyword{static} or \keyword{virtual}.
+shall not be declared \keyword{static}.
 \begin{example}
 \begin{codeblock}
 struct C {