From 5f870260544c0c56484b3c3e0e111a666b148d29 Mon Sep 17 00:00:00 2001
From: Wolfgang Bangerth <bangerth@colostate.edu>
Date: Mon, 19 Oct 2020 19:26:05 -0600
Subject: [PATCH] Move the order of member variables in ParticleHandler around.

---
 include/deal.II/particles/particle_handler.h | 16 ++++++++++------
 source/particles/particle_handler.cc         |  4 ++--
 2 files changed, 12 insertions(+), 8 deletions(-)

diff --git a/include/deal.II/particles/particle_handler.h b/include/deal.II/particles/particle_handler.h
index fd0b345fd1..5752de864e 100644
--- a/include/deal.II/particles/particle_handler.h
+++ b/include/deal.II/particles/particle_handler.h
@@ -786,6 +786,16 @@ namespace Particles
     SmartPointer<const Mapping<dim, spacedim>, ParticleHandler<dim, spacedim>>
       mapping;
 
+    /**
+     * This object owns and organizes the memory for all particle
+     * properties. Since particles reference the property pool, the
+     * latter has to be destroyed *after* the particles are destroyed.
+     * This is achieved by making sure the `property_pool` member variable
+     * precedes the declaration of the `particles` and `ghost_particles`
+     * members.
+     */
+    std::unique_ptr<PropertyPool> property_pool;
+
     /**
      * Set of particles currently living in the local domain, organized by
      * the level/index of the cell they are in.
@@ -821,12 +831,6 @@ namespace Particles
      */
     types::particle_index next_free_particle_index;
 
-    /**
-     * This object owns and organizes the memory for all particle
-     * properties.
-     */
-    std::unique_ptr<PropertyPool> property_pool;
-
     /**
      * A function that can be registered by calling
      * register_additional_store_load_functions. It is called when serializing
diff --git a/source/particles/particle_handler.cc b/source/particles/particle_handler.cc
index 2376c51dc0..7261572fa3 100644
--- a/source/particles/particle_handler.cc
+++ b/source/particles/particle_handler.cc
@@ -87,12 +87,12 @@ namespace Particles
   template <int dim, int spacedim>
   ParticleHandler<dim, spacedim>::ParticleHandler()
     : triangulation()
+    , property_pool(std::make_unique<PropertyPool>(0))
     , particles()
     , ghost_particles()
     , global_number_of_particles(0)
     , global_max_particles_per_cell(0)
     , next_free_particle_index(0)
-    , property_pool(std::make_unique<PropertyPool>(0))
     , size_callback()
     , store_callback()
     , load_callback()
@@ -108,12 +108,12 @@ namespace Particles
     const unsigned int                  n_properties)
     : triangulation(&triangulation, typeid(*this).name())
     , mapping(&mapping, typeid(*this).name())
+    , property_pool(std::make_unique<PropertyPool>(n_properties))
     , particles()
     , ghost_particles()
     , global_number_of_particles(0)
     , global_max_particles_per_cell(0)
     , next_free_particle_index(0)
-    , property_pool(std::make_unique<PropertyPool>(n_properties))
     , size_callback()
     , store_callback()
     , load_callback()
-- 
2.39.5