Merge pull request #3076 from E3SM-Project/mahf708/field-utils/views-…

…are-equal-0

support views_are_equal for rank-0

components/eamxx/src/share/field/field_utils_impl.hpp

@@ -36,6 +36,16 @@ bool views_are_equal(const Field& f1, const Field& f2, const ekat::Comm* comm)
   bool same_locally = true;
   const auto& dims = l1.dims();
   switch (l1.rank()) {
+    case 0:
+      {
+        auto v1 = f1.template get_strided_view<ST,Host>();
+        auto v2 = f2.template get_strided_view<ST,Host>();
+        if (v1() != v2()) {
+          same_locally = false;
+          break;
+        }
+        break;
+      }
     case 1:
       {
         auto v1 = f1.template get_strided_view<ST*,Host>();

components/eamxx/src/share/tests/field_utils.cpp

@@ -37,6 +37,31 @@ TEST_CASE("utils") {
   f1.get_header().get_alloc_properties().request_allocation(P8::n);
   f1.allocate_view();
 
+  SECTION("compare-rank-0") {
+    // create two fields with rank-0 and get their views
+    std::vector<FieldTag> tags_0 = {};
+    std::vector<int> dims_0      = {};
+    FieldIdentifier fid_01("field_01", {tags_0, dims_0}, m / s, "some_grid");
+    FieldIdentifier fid_02("field_02", {tags_0, dims_0}, m / s, "some_grid");
+    Field f01(fid_01);
+    Field f02(fid_02);
+    f01.allocate_view();
+    f02.allocate_view();
+    auto f01v = f01.get_view<Real>();
+    auto f02v = f02.get_view<Real>();
+    // fill the views with the same values
+    Real val = 54321;
+    Kokkos::deep_copy(f01v, val);
+    Kokkos::deep_copy(f02v, val);
+    // check that the views are equal
+    REQUIRE(views_are_equal(f01, f02));
+
+    // fill the views with different values
+    Kokkos::deep_copy(f02v, 1 / val);
+    // check that the views are not equal
+    REQUIRE(not views_are_equal(f01, f02));
+  }
+
   SECTION ("compare") {
 
     Field f2(fid);