From e7e39e9ed6ad5e6bd61fe54ee76615cb686cb4e5 Mon Sep 17 00:00:00 2001
From: Kenneth Moreland <kmorel@sandia.gov>
Date: Mon, 19 Feb 2018 10:13:07 -0700
Subject: [PATCH] Fix including empty range

There was a bug where if you included an empty range into another range,
the range suddenly became infinite. This is because empty ranges have
the max at -infinity and the min at infinity. If you just include the
endpoints independently (which is what include does), then the min gets
-infinity and the max gets infinity. This gets a check to make sure that
empty ranges are ignored.
---
 vtkm/Range.h                    | 7 +++++--
 vtkm/testing/UnitTestBounds.cxx | 7 +++++++
 vtkm/testing/UnitTestRange.cxx  | 6 ++++++
 3 files changed, 18 insertions(+), 2 deletions(-)

diff --git a/vtkm/Range.h b/vtkm/Range.h
index 240131794..e46b06a06 100644
--- a/vtkm/Range.h
+++ b/vtkm/Range.h
@@ -144,8 +144,11 @@ struct Range
   VTKM_EXEC_CONT
   void Include(const vtkm::Range& range)
   {
-    this->Include(range.Min);
-    this->Include(range.Max);
+    if (range.IsNonEmpty())
+    {
+      this->Include(range.Min);
+      this->Include(range.Max);
+    }
   }
 
   /// \b Return the union of this and another range.
diff --git a/vtkm/testing/UnitTestBounds.cxx b/vtkm/testing/UnitTestBounds.cxx
index 52bc76f46..43b3b369c 100644
--- a/vtkm/testing/UnitTestBounds.cxx
+++ b/vtkm/testing/UnitTestBounds.cxx
@@ -33,6 +33,13 @@ void TestBounds()
   vtkm::Bounds emptyBounds;
   VTKM_TEST_ASSERT(!emptyBounds.IsNonEmpty(), "Non empty bounds not empty.");
 
+  vtkm::Bounds emptyBounds2;
+  VTKM_TEST_ASSERT(!emptyBounds2.IsNonEmpty(), "2nd empty bounds not empty.");
+  VTKM_TEST_ASSERT(!emptyBounds.Union(emptyBounds2).IsNonEmpty(),
+                   "Union of empty bounds not empty.");
+  emptyBounds2.Include(emptyBounds);
+  VTKM_TEST_ASSERT(!emptyBounds2.IsNonEmpty(), "Include empty in empty is not empty.");
+
   std::cout << "Single value bounds." << std::endl;
   vtkm::Bounds singleValueBounds(1.0, 1.0, 2.0, 2.0, 3.0, 3.0);
   VTKM_TEST_ASSERT(singleValueBounds.IsNonEmpty(), "Empty?");
diff --git a/vtkm/testing/UnitTestRange.cxx b/vtkm/testing/UnitTestRange.cxx
index 1238ca541..c2e16b37f 100644
--- a/vtkm/testing/UnitTestRange.cxx
+++ b/vtkm/testing/UnitTestRange.cxx
@@ -32,6 +32,12 @@ void TestRange()
   VTKM_TEST_ASSERT(!emptyRange.IsNonEmpty(), "Non empty range not empty.");
   VTKM_TEST_ASSERT(test_equal(emptyRange.Length(), 0.0), "Bad length.");
 
+  vtkm::Range emptyRange2;
+  VTKM_TEST_ASSERT(!emptyRange2.IsNonEmpty(), "2nd empty range not empty.");
+  VTKM_TEST_ASSERT(!emptyRange.Union(emptyRange2).IsNonEmpty(), "Union of empty ranges not empty.");
+  emptyRange2.Include(emptyRange);
+  VTKM_TEST_ASSERT(!emptyRange2.IsNonEmpty(), "Include empty in empty is not empty.");
+
   std::cout << "Single value range." << std::endl;
   vtkm::Range singleValueRange(5.0, 5.0);
   VTKM_TEST_ASSERT(singleValueRange.IsNonEmpty(), "Empty?");