From: Wolfgang Bangerth <bangerth@colostate.edu>
Date: Thu, 13 Jan 2022 04:51:39 +0000 (-0700)
Subject: Small updates to the Serial documentation.
X-Git-Tag: v9.4.0-rc1~609^2
X-Git-Url: https://gitweb.dealii.org/cgi-bin/gitweb.cgi?a=commitdiff_plain;h=refs%2Fpull%2F13235%2Fhead;p=dealii.git

Small updates to the Serial documentation.
---

diff --git a/include/deal.II/base/mpi_consensus_algorithms.templates.h b/include/deal.II/base/mpi_consensus_algorithms.templates.h
index 1fd79d17f3..1e216c979a 100644
--- a/include/deal.II/base/mpi_consensus_algorithms.templates.h
+++ b/include/deal.II/base/mpi_consensus_algorithms.templates.h
@@ -610,10 +610,19 @@ namespace Utilities
       {
         const auto targets = this->process.compute_targets();
 
+        // The only valid target for a serial program is itself.
         if (targets.size() != 0)
           {
+            Assert(targets.size() == 1,
+                   ExcMessage(
+                     "On a single process, the only valid target "
+                     "is process zero (the process itself), which can only be "
+                     "listed once."));
             AssertDimension(targets[0], 0);
 
+            // Since the caller indicates that there is a target, and since we
+            // know that it is the current process, let the process send
+            // something to itself.
             std::vector<T1> send_buffer;
             std::vector<T2> recv_buffer;
             std::vector<T2> request_buffer;