From 43912638f7f10b15c9b2bd12115da9e84b505190 Mon Sep 17 00:00:00 2001
From: David Wells <drwells@email.unc.edu>
Date: Thu, 15 Aug 2024 10:03:06 -0600
Subject: [PATCH] Drop support for p4est versions older than 2.2.

We already have several features which depend on this version.
---
 cmake/configure/configure_50_p4est.cmake      |  4 +--
 .../incompatibilities/20240815DavidWells      |  4 +++
 source/distributed/tria.cc                    | 27 +------------------
 3 files changed, 7 insertions(+), 28 deletions(-)
 create mode 100644 doc/news/changes/incompatibilities/20240815DavidWells

diff --git a/cmake/configure/configure_50_p4est.cmake b/cmake/configure/configure_50_p4est.cmake
index 13992d1d1f..77c170d967 100644
--- a/cmake/configure/configure_50_p4est.cmake
+++ b/cmake/configure/configure_50_p4est.cmake
@@ -26,9 +26,9 @@ macro(feature_p4est_find_external var)
     set(${var} TRUE)
 
     #
-    # We require at least version 2.0
+    # We require at least version 2.2
     #
-    set(_version_required 2.0)
+    set(_version_required 2.2)
     if(P4EST_VERSION VERSION_LESS ${_version_required})
       message(STATUS "Insufficient p4est installation found: "
         "At least version ${_version_required} is required."
diff --git a/doc/news/changes/incompatibilities/20240815DavidWells b/doc/news/changes/incompatibilities/20240815DavidWells
new file mode 100644
index 0000000000..78021f68c7
--- /dev/null
+++ b/doc/news/changes/incompatibilities/20240815DavidWells
@@ -0,0 +1,4 @@
+Changed: The minimum version of p4est compatible with deal.II has been
+increased to 2.2.
+<br>
+(David Wells, 2024/08/15)
diff --git a/source/distributed/tria.cc b/source/distributed/tria.cc
index 623822953d..27f27e1a53 100644
--- a/source/distributed/tria.cc
+++ b/source/distributed/tria.cc
@@ -618,7 +618,6 @@ namespace
       }
   }
 
-#  ifdef P4EST_SEARCH_LOCAL
   template <int dim>
   class PartitionSearch
   {
@@ -1193,7 +1192,7 @@ namespace
 
     are_vertices_initialized = true;
   }
-#  endif //  P4EST_SEARCH_LOCAL defined
+
 
 
   /**
@@ -1977,19 +1976,6 @@ namespace parallel
                             this->data_serializer.dest_sizes_variable.end(),
                             std::vector<int>::size_type(0)));
 
-#  if DEAL_II_P4EST_VERSION_GTE(2, 0, 65, 0)
-#  else
-          // ----- WORKAROUND -----
-          // An assertion in p4est prevents us from sending/receiving no data
-          // at all, which is mandatory if one of our processes does not own
-          // any quadrant. This bypasses the assertion from being triggered.
-          //   - see: https://github.com/cburstedde/p4est/issues/48
-          if (this->data_serializer.src_sizes_variable.empty())
-            this->data_serializer.src_sizes_variable.resize(1);
-          if (this->data_serializer.dest_sizes_variable.empty())
-            this->data_serializer.dest_sizes_variable.resize(1);
-#  endif
-
           // Execute variable size transfer.
           dealii::internal::p4est::functions<dim>::transfer_custom(
             parallel_forest->global_first_quadrant,
@@ -3202,16 +3188,6 @@ namespace parallel
     std::vector<types::subdomain_id> Triangulation<dim, spacedim>::
       find_point_owner_rank(const std::vector<Point<dim>> &points)
     {
-#  ifndef P4EST_SEARCH_LOCAL
-      (void)points;
-      AssertThrow(
-        false,
-        ExcMessage(
-          "This function is only available if p4est is version 2.2 and higher."));
-      // Just return to satisfy compiler
-      return std::vector<unsigned int>(1,
-                                       dealii::numbers::invalid_subdomain_id);
-#  else
       // We can only use this function if vertices are communicated to p4est
       AssertThrow(this->are_vertices_communicated_to_p4est(),
                   ExcMessage(
@@ -3298,7 +3274,6 @@ namespace parallel
       sc_array_destroy_null(&point_sc_array);
 
       return owner_rank;
-#  endif // P4EST_SEARCH_LOCAL defined
     }
 
 
-- 
2.39.5