Merge pull request #4277 from bangerth/use-unique-ptr

Use std::unique_ptr instead of std::shared_ptr in FESystem.

diff --cc include/deal.II/fe/fe_system.h
index 20b7cb3c33d0e3ef7c75bed2ab92871a3d4ae51b,c8a3e6b9fa22773842b0f4c04c04283c8dab5a64..9e1870529bde75a325f0a5d86027b0ee55663885
--- 1/include/deal.II/fe/fe_system.h
--- 2/include/deal.II/fe/fe_system.h
+++ b/include/deal.II/fe/fe_system.h
@@@ -966,8 -962,15 +968,8 @@@ private
     * This object contains a pointer to each contributing element of a mixed
     * discretization and its multiplicity. It is created by the constructor and
     * constant afterwards.
 -   *
 -   * The pointers are managed as shared pointers. This ensures that we can use
 -   * the copy constructor of this class without having to manage cloning the
 -   * elements themselves. Since finite element objects do not contain any
 -   * state, this also allows multiple copies of an FESystem object to share
 -   * pointers to the underlying base finite elements. The last one of these
 -   * copies around will then delete the pointer to the base elements.
     */
-   std::vector<std::pair<std::shared_ptr<const FiniteElement<dim,spacedim> >,
+   std::vector<std::pair<std::unique_ptr<const FiniteElement<dim,spacedim> >,
        unsigned int> >
        base_elements;
  

diff --cc source/fe/fe_system.cc
Simple merge