createOperations(): make it work when transforming between CompoundCRS and Geog3D when the DB has only VertCS to Geog2D

This is needed to fix cases that would not work if using the promoteTo3D()/--3d
functionnality just added per a6e1d72890615b42f54edad9b17acff8e7623844
In some cases, the EPSG database only contains a Geographic 2D CRS (like NAD83),
without a 3D version. Consequently vertical transformations between that
Geographic CRS and a Vertical CRS are only available with a 2D CRS code
(kind of a bug in modelization by the way...). So when promoting the
Geographic 2D CRS to a 3D one, we suddenly cannot find the available
transformations any more. So in such situation, try to fallback to the
2D CRS to restore the capability to find the available transformations.

1 files changed, 26 insertions, 0 deletions

diff --git a/test/unit/test_operation.cpp b/test/unit/test_operation.cpp
index 38f0864d..21275284 100644
--- a/test/unit/test_operation.cpp
+++ b/test/unit/test_operation.cpp
@@ -6763,6 +6763,32 @@ TEST(operation, compoundCRS_to_geogCRS_3D_context) {
 
 // ---------------------------------------------------------------------------
 
+TEST(operation, compoundCRS_to_geogCRS_2D_promote_to_3D_context) {
+    auto authFactory =
+        AuthorityFactory::create(DatabaseContext::create(), "EPSG");
+    auto ctxt = CoordinateOperationContext::create(authFactory, nullptr, 0.0);
+    // NAD83 + NAVD88 height
+    auto srcObj = createFromUserInput("EPSG:4269+5703",
+                                      authFactory->databaseContext(), false);
+    auto src = nn_dynamic_pointer_cast<CRS>(srcObj);
+    ASSERT_TRUE(src != nullptr);
+    auto nnSrc = NN_NO_CHECK(src);
+    auto dst = authFactory->createCoordinateReferenceSystem("4269"); // NAD83
+    dst = dst->promoteTo3D(std::string(), authFactory->databaseContext());
+    {
+        auto list = CoordinateOperationFactory::create()->createOperations(
+            nnSrc, dst, ctxt);
+        ASSERT_GE(list.size(), 8U);
+    }
+    {
+        auto list = CoordinateOperationFactory::create()->createOperations(
+            dst, nnSrc, ctxt);
+        ASSERT_GE(list.size(), 8U);
+    }
+}
+
+// ---------------------------------------------------------------------------
+
 TEST(operation, compoundCRS_from_WKT2_to_geogCRS_3D_context) {
     auto authFactory =
         AuthorityFactory::create(DatabaseContext::create(), "EPSG");