CWG1353 Array and variant members and deleted special member functions

Author: burblebee

source/classes.tex

@@ -1247,38 +1247,34 @@
 \pnum
 A defaulted default constructor for class \tcode{X} is defined as deleted if:
 \begin{itemize}
-\item \tcode{X} is a union that has a variant member
-with a non-trivial default constructor and
-no variant member of \tcode{X} has a default member initializer,
-
-\item \tcode{X} is a non-union class that has a variant member \tcode{M}
-with a non-trivial default constructor and
-no variant member of the anonymous union containing \tcode{M}
-has a default member initializer,
-
 \item any non-static data member with no default member initializer\iref{class.mem} is
 of reference type,
 
-\item any non-variant non-static data member of const-qualified type (or array
-thereof) with no \grammarterm{brace-or-equal-initializer}
+\item any non-variant non-static data member of const-qualified type
+(or possibly multi-dimensional array thereof)
+with no \grammarterm{brace-or-equal-initializer}
 is not const-default-constructible\iref{dcl.init},
 
 \item \tcode{X} is a union and all of its variant members are of const-qualified
-type (or array thereof),
+type (or possibly multi-dimensional array thereof),
 
 \item \tcode{X} is a non-union class and all members of any anonymous union member are
-of const-qualified type (or array thereof),
+of const-qualified type (or possibly multi-dimensional array thereof),
 
 \item any potentially constructed subobject, except for a non-static data member
-with a \grammarterm{brace-or-equal-initializer}, has
-class type \tcode{M} (or array thereof) and either \tcode{M}
-has no default constructor or overload resolution\iref{over.match}
-as applied to find \tcode{M}'s corresponding
-constructor results in an ambiguity or in a function that is deleted or
-inaccessible from the defaulted default constructor, or
-
-\item any potentially constructed subobject has a type
-with a destructor that is deleted or inaccessible from the defaulted default
+with a \grammarterm{brace-or-equal-initializer}
+or a variant member of a union where another non-static data member
+has a \grammarterm{brace-or-equal-initializer},
+has class type \tcode{M} (or possibly multi-dimensional array thereof)
+and overload resolution\iref{over.match}
+as applied to find \tcode{M}'s corresponding constructor
+either does not result in a usable candidate\iref{over.match.general}
+or, in the case of a variant member, selects a non-trivial function, or
+
+\item any potentially constructed subobject has
+class type \tcode{M} (or possibly multi-dimensional array thereof) and
+\tcode{M} has
+a destructor that is deleted or inaccessible from the defaulted default
 constructor.
 \end{itemize}
 
@@ -1543,18 +1539,16 @@
   \tcode{X} is defined as deleted\iref{dcl.fct.def.delete} if \tcode{X} has:
 \begin{itemize}
 \item a potentially constructed subobject of type
-  \tcode{M} (or array thereof) that cannot be copied/moved because
+  \tcode{M} (or possibly multi-dimensional array thereof) for which
   overload resolution\iref{over.match}, as applied to find
-  \tcode{M}'s
-  corresponding constructor, results in an ambiguity or
-  a function that is deleted or inaccessible from the
-  defaulted constructor,
-
-\item a variant member whose corresponding constructor
-  as selected by overload resolution is non-trivial,
-
-\item any potentially constructed subobject of a type
-  with a destructor that is deleted or inaccessible from the defaulted
+  \tcode{M}'s corresponding constructor,
+  either does not result in a usable candidate\iref{over.match.general} or,
+  in the case of a variant member, selects a non-trivial function,
+
+\item any potentially constructed subobject of
+  class type \tcode{M} (or possibly multi-dimensional array thereof)
+  where \tcode{M} has
+  a destructor that is deleted or inaccessible from the defaulted
   constructor, or,
 
 \item for the copy constructor, a non-static data member of rvalue reference type.
@@ -1823,21 +1817,19 @@
 A defaulted copy/move assignment operator for
 class \tcode{X} is defined as deleted if \tcode{X} has:
 \begin{itemize}
-\item a variant member with a non-trivial corresponding assignment operator and
-  \tcode{X} is a union-like class, or
-
 \item a non-static data member of \keyword{const} non-class
-  type (or array thereof), or
+  type (or possibly multi-dimensional array thereof), or
 
 \item a non-static data member of reference type, or
 
 \item a direct non-static data member of class type \tcode{M}
-  (or array thereof) or a direct base class \tcode{M}
+  (or possibly multi-dimensional array thereof) or
+  a direct base class \tcode{M}
   that cannot be copied/moved because overload resolution
  \iref{over.match}, as applied to find \tcode{M}'s corresponding
-  assignment operator, results in an ambiguity or
-  a function that is deleted or inaccessible from the
-  defaulted assignment operator.
+  assignment operator,
+  either does not result in a usable candidate\iref{over.match.general} or,
+  in the case of a variant member, selects a non-trivial function.
 \end{itemize}
 
 \begin{note}
@@ -2070,13 +2062,11 @@
 A defaulted destructor for a class
   \tcode{X} is defined as deleted if:
 \begin{itemize}
-\item \tcode{X} is a union-like class that has a variant
-  member with a non-trivial destructor,
-
 \item any potentially constructed subobject has class type
-  \tcode{M} (or array thereof) and
-  \tcode{M} has a deleted destructor or a destructor
-  that is inaccessible from the defaulted destructor,
+  \tcode{M} (or possibly multi-dimensional array thereof) and
+  \tcode{M} has a destructor that is deleted or
+  is inaccessible from the defaulted destructor or,
+  in the case of a variant member, is non-trivial,
 
 \item or, for a virtual destructor, lookup of the non-array deallocation
   function results in an ambiguity or in a function that is deleted or