WKT2_2018: export ID in base crs node, when there is none on top of upper node

This is the standard logic, that is now possible since ID is
allowed in BASEGEOGCRS and similar node

4 files changed, 41 insertions, 5 deletions

diff --git a/include/proj/io.hpp b/include/proj/io.hpp
index 8cf8e3c4..90163001 100644
--- a/include/proj/io.hpp
+++ b/include/proj/io.hpp
@@ -195,8 +195,7 @@ class PROJ_GCC_DLL WKTFormatter {
         WKT2_2018_SIMPLIFIED,
 
         /** WKT1 as traditionally output by GDAL, deriving from OGC 01-009.
-            A notable departuPROJ_GCC_DLLre from WKT1_GDAL with respect to OGC
-           01-009 is
+            A notable departure from WKT1_GDAL with respect to OGC 01-009 is
             that in WKT1_GDAL, the unit of the PRIMEM value is always degrees.
            */
         WKT1_GDAL,
diff --git a/src/iso19111/crs.cpp b/src/iso19111/crs.cpp
index 74f6f999..9779d817 100644
--- a/src/iso19111/crs.cpp
+++ b/src/iso19111/crs.cpp
@@ -2428,9 +2428,13 @@ void DerivedCRS::baseExportToWKT(io::WKTFormatter *formatter,
     formatter->addQuotedString(nameStr());
 
     const auto &l_baseCRS = d->baseCRS_;
-    formatter->startNode(baseKeyword, !l_baseCRS->identifiers().empty());
+    formatter->startNode(baseKeyword, formatter->use2018Keywords() &&
+                                          !l_baseCRS->identifiers().empty());
     formatter->addQuotedString(l_baseCRS->nameStr());
     l_baseCRS->exportDatumOrDatumEnsembleToWkt(formatter);
+    if (formatter->use2018Keywords() && formatter->outputId()) {
+        l_baseCRS->formatID(formatter);
+    }
     formatter->endNode();
 
     formatter->setUseDerivingConversion(true);
@@ -2658,7 +2662,7 @@ void ProjectedCRS::_exportToWKT(io::WKTFormatter *formatter) const {
              dynamic_cast<const GeographicCRS *>(l_baseCRS.get()))
                 ? io::WKTConstants::BASEGEOGCRS
                 : io::WKTConstants::BASEGEODCRS,
-            !l_baseCRS->identifiers().empty());
+            formatter->use2018Keywords() && !l_baseCRS->identifiers().empty());
         formatter->addQuotedString(l_baseCRS->nameStr());
         l_baseCRS->exportDatumOrDatumEnsembleToWkt(formatter);
         // insert ellipsoidal cs unit when the units of the map
@@ -2669,6 +2673,9 @@ void ProjectedCRS::_exportToWKT(io::WKTFormatter *formatter) const {
             geodeticCRSAxisList[0]->unit()._exportToWKT(formatter);
         }
         l_baseCRS->primeMeridian()->_exportToWKT(formatter);
+        if (formatter->use2018Keywords() && formatter->outputId()) {
+            l_baseCRS->formatID(formatter);
+        }
         formatter->endNode();
     } else {
         const auto oldAxisOutputRule = formatter->outputAxis();
diff --git a/test/unit/test_crs.cpp b/test/unit/test_crs.cpp
index 02586877..bfd6ee66 100644
--- a/test/unit/test_crs.cpp
+++ b/test/unit/test_crs.cpp
@@ -4562,7 +4562,8 @@ TEST(crs, DerivedVerticalCRS_WKT2) {
 
     auto expected = "VERTCRS[\"Derived vertCRS\",\n"
                     "    BASEVERTCRS[\"ODN height\",\n"
-                    "        VDATUM[\"Ordnance Datum Newlyn\"]],\n"
+                    "        VDATUM[\"Ordnance Datum Newlyn\",\n"
+                    "            ID[\"EPSG\",5101]]],\n"
                     "    DERIVINGCONVERSION[\"unnamed\",\n"
                     "        METHOD[\"PROJ unimplemented\"]],\n"
                     "    CS[vertical,1],\n"
diff --git a/test/unit/test_io.cpp b/test/unit/test_io.cpp
index 1d097d9b..2181b321 100644
--- a/test/unit/test_io.cpp
+++ b/test/unit/test_io.cpp
@@ -1667,6 +1667,35 @@ TEST(wkt_parse, wkt2_2018_projected_with_id_in_basegeodcrs) {
 
 // ---------------------------------------------------------------------------
 
+TEST(wkt_parse, wkt2_2018_projected_no_id_but_id_in_basegeodcrs) {
+    auto wkt = "PROJCRS[\"WGS 84 / UTM zone 31N\",\n"
+               "    BASEGEOGCRS[\"WGS 84\",\n"
+               "        DATUM[\"World Geodetic System 1984\",\n"
+               "            ELLIPSOID[\"WGS 84\",6378137,298.257223563]],\n"
+               "        ID[\"EPSG\",4326]],\n"
+               "    CONVERSION[\"UTM zone 31N\",\n"
+               "        METHOD[\"Transverse Mercator\"],\n"
+               "        PARAMETER[\"Latitude of natural origin\",0],\n"
+               "        PARAMETER[\"Longitude of natural origin\",3],\n"
+               "        PARAMETER[\"Scale factor at natural origin\",0.9996],\n"
+               "        PARAMETER[\"False easting\",500000],\n"
+               "        PARAMETER[\"False northing\",0]],\n"
+               "    CS[Cartesian,2],\n"
+               "        AXIS[\"(E)\",east],\n"
+               "        AXIS[\"(N)\",north],\n"
+               "        UNIT[\"metre\",1]]";
+    auto obj = WKTParser().createFromWKT(wkt);
+    auto crs = nn_dynamic_pointer_cast<ProjectedCRS>(obj);
+    ASSERT_TRUE(crs != nullptr);
+
+    auto got_wkt = crs->exportToWKT(
+        WKTFormatter::create(WKTFormatter::Convention::WKT2_2018).get());
+    EXPECT_TRUE(got_wkt.find("ID[\"EPSG\",4326]]") != std::string::npos)
+        << got_wkt;
+}
+
+// ---------------------------------------------------------------------------
+
 TEST(wkt_parse, wkt2_2018_simplified_projected) {
     auto wkt = "PROJCRS[\"WGS 84 / UTM zone 31N\",\n"
                "    BASEGEOGCRS[\"WGS 84\",\n"