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Cleanup of [class.virtual] #3987

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36 changes: 16 additions & 20 deletions source/classes.tex
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Expand Up @@ -3748,7 +3748,7 @@

\pnum
A non-static member function is a \defnadj{virtual}{function}
if it is first declared with the keyword \tcode{virtual} or
if it is declared with the keyword \tcode{virtual} or
if it overrides a virtual member function declared in a base class
(see below).\footnote{The use of the \tcode{virtual} specifier in the
declaration of an overriding function is valid but redundant (has empty
Expand All @@ -3765,24 +3765,21 @@
any additions for that polymorphic behavior.}

\pnum
If a virtual member function \tcode{vf} is declared in a class
\tcode{Base} and in a class \tcode{Derived}, derived directly or
indirectly from \tcode{Base}, a member function \tcode{vf} with the same
name, parameter-type-list\iref{dcl.fct}, cv-qualification, and ref-qualifier
(or absence of same) as \tcode{Base::vf} is declared,
then \tcode{Derived::vf} \term{overrides}\footnote{A function
A non-template non-static member function declared in a class \tcode{D}
\defn{overrides} a virtual member function declared
in a base class of \tcode{D} if both have the same name,
parameter-type-list\iref{dcl.fct}, \grammarterm{cv-qualifier-seq},
and \grammarterm{ref-qualifier} (or absence thereof).
\footnote{A function
with the same name but a different parameter list\iref{over}
as a virtual function is not necessarily virtual and
does not override. Access control\iref{class.access} is not considered in
determining overriding.}
\tcode{Base::vf}. For convenience we say that any virtual function
overrides itself.
\indextext{overrider!final}%
A virtual member function \tcode{C::vf} of a class object \tcode{S} is a \defn{final
overrider} unless the most derived class\iref{intro.object} of which \tcode{S} is a
base class subobject (if any) declares or inherits another member function that overrides
\tcode{vf}. In a derived class, if a virtual member function of a base class subobject
has more than one final overrider the program is ill-formed.
The \denfx{final overrider}{overrider!final} of a virtual function \tcode{F} in a class \tcode{C}
is \tcode{F} if no member of \tcode{C} overrides \tcode{F},
and otherwise is the member \tcode{G} of \tcode{C} that overrides \tcode{F}
and itself is not overridden by any other member of \tcode{C};
there shall be exactly one such \tcode{G}.
\begin{example}
\begin{codeblock}
struct A {
Expand Down Expand Up @@ -3838,9 +3835,8 @@
\end{note}

\pnum
If a virtual function \tcode{f} in some class \tcode{B} is marked with the
\grammarterm{virt-specifier} \tcode{final} and in a class \tcode{D} derived from \tcode{B}
a function \tcode{D::f} overrides \tcode{B::f}, the program is ill-formed.
A virtual function shall not override a function declared
with the \grammarterm{virt-specifier} \tcode{final}.
\begin{example}
\begin{codeblock}
struct B {
Expand All @@ -3854,8 +3850,8 @@
\end{example}

\pnum
If a virtual function is marked with the \grammarterm{virt-specifier} \tcode{override} and
does not override a member function of a base class, the program is ill-formed.
A function declared with the \grammarterm{virt-specifier} \tcode{override}
shall override a virtual function.
\begin{example}
\begin{codeblock}
struct B {
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2 changes: 2 additions & 0 deletions source/templates.tex
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Expand Up @@ -2597,6 +2597,7 @@
\end{example}

\pnum
\begin{note}
A specialization of
a member function template does not override a virtual function from a
base class.
Expand All @@ -2612,6 +2613,7 @@
};
\end{codeblock}
\end{example}
\end{note}

\pnum
A specialization of a
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