From 1223da98f791f67cf678389ae594a960184047f9 Mon Sep 17 00:00:00 2001
From: Will Bainbridge <http://cfd.direct>
Date: Mon, 4 Jun 2018 10:47:49 +0100
Subject: [PATCH] cyclicRepeatAMI: Added error message for zero-sized transform
 patch

Sometimes decomposition can remove a cyclic patch entirely, converting
it into a processor cyclic. If this patch is being used to specify the
transform for a cyclicRepeatAMI patch then the calculation will fail.
This change adds a check for this situation, and errors with the
suggestion that the transform patch be preserved during decomposition.
---
 .../cyclicRepeatAMIPolyPatch.C                   | 16 ++++++++++++++--
 1 file changed, 14 insertions(+), 2 deletions(-)

diff --git a/src/meshTools/AMIInterpolation/patches/cyclicRepeatAMI/cyclicRepeatAMIPolyPatch/cyclicRepeatAMIPolyPatch.C b/src/meshTools/AMIInterpolation/patches/cyclicRepeatAMI/cyclicRepeatAMIPolyPatch/cyclicRepeatAMIPolyPatch.C
index dd2d391d7..a95adcc92 100644
--- a/src/meshTools/AMIInterpolation/patches/cyclicRepeatAMI/cyclicRepeatAMIPolyPatch/cyclicRepeatAMIPolyPatch.C
+++ b/src/meshTools/AMIInterpolation/patches/cyclicRepeatAMI/cyclicRepeatAMIPolyPatch/cyclicRepeatAMIPolyPatch.C
@@ -82,8 +82,9 @@ void Foam::cyclicRepeatAMIPolyPatch::resetAMI() const
     }
 
     Info<< indent << typeName <<" : Creating addressing and weights between "
-        << this->size() << " source faces and " << neighbPatch().size()
-        << " target faces" << endl;
+        << returnReduce(this->size(), sumOp<label>()) << " source faces and "
+        << returnReduce(neighbPatch().size(), sumOp<label>()) << " target faces"
+        << endl;
 
     // Get the transform associated with the transform patch
     vectorTensorTransform t;
@@ -129,6 +130,17 @@ void Foam::cyclicRepeatAMIPolyPatch::resetAMI() const
 
         reduce(bt, keepIfTrueOp<vectorTensorTransform>());
 
+        if (!bt.first())
+        {
+            FatalErrorInFunction
+                << "Transform patch " << transformPatch.name() << " for "
+                << typeName << " patch " << name() << " has zero faces. It may "
+                << "have been converted to a processor cyclic during "
+                << "decomposition. Consider adding " << transformPatch.name()
+                << " and it's neighbour to the list of preserved patches."
+                << exit(FatalError);
+        }
+
         t = bt.second();
     }
     const vectorTensorTransform tInv(inv(t));