Remove 'dummy' members and allow empty structs.

Empty structs are implementation-dependent in C, but are acceptable in
C++. Therefore unused private members are not needed (and they cause
clang to generate warnings).

diff --git a/include/deal.II/base/data_out_base.h b/include/deal.II/base/data_out_base.h
index 768ab37217ff3d46c503dddb0a9c45c4d33a8ad6..a8e47c9a3246fec176895f0297a8288fb8a7a48a 100644 (file)
--- a/include/deal.II/base/data_out_base.h
+++ b/include/deal.II/base/data_out_base.h
@@ -509,15 +509,7 @@ namespace DataOutBase
    * @ingroup output
    */
   struct GnuplotFlags : public OutputFlagsBase<GnuplotFlags>
-  {
-  private:
-    /**
-     * Dummy entry to suppress compiler warnings when copying an empty
-     * structure. Remove this member when adding the first flag to this
-     * structure (and remove the <tt>private</tt> as well).
-     */
-    int dummy;
-  };
+  {};
 
   /**
    * Flags controlling the details of output in Povray format. Several flags
@@ -816,15 +808,7 @@ namespace DataOutBase
    * @ingroup output
    */
   struct GmvFlags : public OutputFlagsBase<GmvFlags>
-  {
-  private:
-    /**
-     * Dummy entry to suppress compiler warnings when copying an empty
-     * structure. Remove this member when adding the first flag to this
-     * structure (and remove the <tt>private</tt> as well).
-     */
-    int dummy;
-  };
+  {};
 
   /**
    * Flags controlling the details of output in Tecplot format.
@@ -977,14 +961,6 @@ namespace DataOutBase
      * what the current readers and writers understand.
      */
     static const unsigned int format_version = 3;
-
-  private:
-    /**
-     * Dummy entry to suppress compiler warnings when copying an empty
-     * structure. Remove this member when adding the first flag to this
-     * structure (and remove the <tt>private</tt> as well).
-     */
-    int dummy;
   };
 
   /**