From 6f300eed62127d3972eaa75a0b1b10fcb91c2967 Mon Sep 17 00:00:00 2001
From: wolf <wolf@0785d39b-7218-0410-832d-ea1e28bc413d>
Date: Tue, 3 Feb 2004 14:54:53 +0000
Subject: [PATCH] In some situations, the C++ standard requires a copy
 constructor to be accessible even if it is not used. In particular, this
 holds when one creates a temporary object and binds it to a const reference.
 In this case, the compiler will usually bind the temporary directly to the
 reference, but a copy constructor will still have to be accessible. An
 example is f(FE_Q<dim>(2)). To allow this to compile, we need to make copy
 constructors accessible, but if they are actually called, we simply throw an
 exception.

git-svn-id: https://svn.dealii.org/trunk@8384 0785d39b-7218-0410-832d-ea1e28bc413d
---
 deal.II/deal.II/include/fe/fe.h        | 24 +++++++++++++++++-------
 deal.II/deal.II/include/fe/fe_system.h |  7 +------
 deal.II/deal.II/source/fe/fe.cc        | 21 +++++++++++++++++++--
 3 files changed, 37 insertions(+), 15 deletions(-)

diff --git a/deal.II/deal.II/include/fe/fe.h b/deal.II/deal.II/include/fe/fe.h
index fcbe0e078b..aaff9e3621 100644
--- a/deal.II/deal.II/include/fe/fe.h
+++ b/deal.II/deal.II/include/fe/fe.h
@@ -2,7 +2,7 @@
 //    $Id$
 //    Version: $Name$
 //
-//    Copyright (C) 1998, 1999, 2000, 2001, 2002, 2003 by the deal.II authors
+//    Copyright (C) 1998, 1999, 2000, 2001, 2002, 2003, 2004 by the deal.II authors
 //
 //    This file is subject to QPL and may not be  distributed
 //    without copyright and license information. Please refer
@@ -55,13 +55,23 @@ template <int dim> class FESystem;
 template <int dim>
 class FiniteElement : public FiniteElementBase<dim>
 {
-  private:
-				     /**
-				      * Copy constructor prohibited.
-				      */
-    FiniteElement(const FESystem<dim>&);
-
   public:
+                                     /**
+                                      * Copy constructor. This one is declared
+                                      * as a public constructor to avoid
+                                      * certain compiler errors when a copy
+                                      * constructor is required even if it is
+                                      * not executed (for example when binding
+                                      * a temporary object to a constant
+                                      * reference). However, if you try to
+                                      * actually call it, it will throw an
+                                      * exception, since copying finite
+                                      * element objects is not really
+                                      * supported. If you want to copy such an
+                                      * object, use the @p{clone} function.
+                                      */
+    FiniteElement (const FiniteElement &);
+    
 				     /**
 				      * Constructor
 				      */
diff --git a/deal.II/deal.II/include/fe/fe_system.h b/deal.II/deal.II/include/fe/fe_system.h
index 29ffd66bf7..3cdc39eb96 100644
--- a/deal.II/deal.II/include/fe/fe_system.h
+++ b/deal.II/deal.II/include/fe/fe_system.h
@@ -2,7 +2,7 @@
 //    $Id$
 //    Version: $Name$
 //
-//    Copyright (C) 1998, 1999, 2000, 2001, 2002, 2003 by the deal.II authors
+//    Copyright (C) 1998, 1999, 2000, 2001, 2002, 2003, 2004 by the deal.II authors
 //
 //    This file is subject to QPL and may not be  distributed
 //    without copyright and license information. Please refer
@@ -71,11 +71,6 @@
 template <int dim>
 class FESystem : public FiniteElement<dim>
 {
-				     /**
-				      * Copy constructor prohibited.
-				      */
-    FESystem(const FESystem<dim>&);
-
   public:
 
 				     /**
diff --git a/deal.II/deal.II/source/fe/fe.cc b/deal.II/deal.II/source/fe/fe.cc
index eabd70b3bd..dd9c5f779b 100644
--- a/deal.II/deal.II/source/fe/fe.cc
+++ b/deal.II/deal.II/source/fe/fe.cc
@@ -2,7 +2,7 @@
 //    $Id$
 //    Version: $Name$
 //
-//    Copyright (C) 1998, 1999, 2000, 2001, 2002, 2003 by the deal.II authors
+//    Copyright (C) 1998, 1999, 2000, 2001, 2002, 2003, 2004 by the deal.II authors
 //
 //    This file is subject to QPL and may not be  distributed
 //    without copyright and license information. Please refer
@@ -621,7 +621,8 @@ compute_n_nonzero_components (const std::vector<std::vector<bool> > &nonzero_com
 template <int dim>
 FiniteElement<dim>::FiniteElement (const FiniteElementData<dim> &fe_data,
 				   const std::vector<bool> &restriction_is_additive_flags,
-				   const std::vector<std::vector<bool> > &nonzero_components) :
+				   const std::vector<std::vector<bool> > &nonzero_components)
+                :
 		FiniteElementBase<dim> (fe_data,
 					restriction_is_additive_flags,
 					nonzero_components)
@@ -629,6 +630,22 @@ FiniteElement<dim>::FiniteElement (const FiniteElementData<dim> &fe_data,
 
 
 
+template <int dim>
+FiniteElement<dim>::FiniteElement (const FiniteElement<dim> &)
+                :
+                FiniteElementBase<dim> (FiniteElementData<dim>(),
+                                        std::vector<bool> (),
+                                        std::vector<std::vector<bool> >())
+{
+  Assert (false,
+          ExcMessage ("Finite element objects don't support copying "
+                      "semantics through the copy constructor. If "
+                      "you want to copy a finite element, use the "
+                      "clone() function."));
+}
+
+
+
 template <int dim>
 FiniteElement<dim>::~FiniteElement ()
 {}
-- 
2.39.5