Delete empty fields from Symbol Fields editor.

Fixes: lp:1784718
* https://bugs.launchpad.net/kicad/+bug/1784718

eeschema/dialogs/dialog_fields_editor_global.cpp

@@ -585,8 +585,10 @@ public:
                 if( !destField && !srcValue.IsEmpty() )
                     destField = comp->AddField( SCH_FIELD( wxPoint( 0, 0 ), -1, comp, srcName ) );
 
-                if( destField )
+                if( destField && !srcValue.IsEmpty() )
                     destField->SetText( srcValue );
+                else
+                    comp->RemoveField( srcName );
             }
         }
 

eeschema/sch_component.cpp

@@ -934,6 +934,19 @@ SCH_FIELD* SCH_COMPONENT::AddField( const SCH_FIELD& aField )
 }
 
 
+void SCH_COMPONENT::RemoveField( const wxString& aFieldName )
+{
+    for( unsigned i = MANDATORY_FIELDS; i < m_Fields.size(); ++i )
+    {
+        if( aFieldName == m_Fields[i].GetName( false ) )
+        {
+            m_Fields.erase( m_Fields.begin() + i );
+            return;
+        }
+    }
+}
+
+
 SCH_FIELD* SCH_COMPONENT::FindField( const wxString& aFieldName, bool aIncludeDefaultFields )
 {
     unsigned start = aIncludeDefaultFields ? 0 : MANDATORY_FIELDS;

eeschema/sch_component.h

@@ -349,6 +349,13 @@ public:
      */
     SCH_FIELD* AddField( const SCH_FIELD& aField );
 
+    /**
+     * Removes a user field from the symbol.
+     * @param aFieldName is the user fieldName to remove.  Attempts to remove a mandatory
+     *                   field or a non-existant field are silently ignored.
+     */
+    void RemoveField( const wxString& aFieldName );
+
     /**
      * Search for a #SCH_FIELD with \a aFieldName
      *