From 3f07b9e0fa109da8f3cd9aab0275cae3600e736c Mon Sep 17 00:00:00 2001
From: Even Rouault <even.rouault@spatialys.com>
Date: Wed, 11 Sep 2019 17:25:35 +0000
Subject: [PATCH] createOperations(): fix conversion from/to PROJ.4 CRS strings
 with non-ISO-cosher options and towgs84/nadgrids

This actually fixes a regression introduced in PROJ 6.2.0
per 78302efb70eb4b49610cda6a60bf9ce39b82264f
that made a conversion like EPSG:4326 to "+proj=something +towgs84/+nadgrids +over +type=crs"
apply the towgs84/nadgrids operation twice.
---
 src/iso19111/coordinateoperation.cpp | 19 +++++++++++++------
 test/unit/test_operation.cpp         | 24 ++++++++++++++++++++++++
 2 files changed, 37 insertions(+), 6 deletions(-)

diff --git a/src/iso19111/coordinateoperation.cpp b/src/iso19111/coordinateoperation.cpp
index e95241634c..9d20b39642 100644
--- a/src/iso19111/coordinateoperation.cpp
+++ b/src/iso19111/coordinateoperation.cpp
@@ -12048,14 +12048,23 @@ CoordinateOperationFactory::Private::createOperations(
     std::vector<CoordinateOperationNNPtr> res;
     const bool allowEmptyIntersection = true;
 
-    const auto &sourceProj4Ext = sourceCRS->getExtensionProj4();
-    const auto &targetProj4Ext = targetCRS->getExtensionProj4();
+    auto boundSrc = dynamic_cast<const crs::BoundCRS *>(sourceCRS.get());
+    auto boundDst = dynamic_cast<const crs::BoundCRS *>(targetCRS.get());
+
+    const auto &sourceProj4Ext = boundSrc
+                                     ? boundSrc->baseCRS()->getExtensionProj4()
+                                     : sourceCRS->getExtensionProj4();
+    const auto &targetProj4Ext = boundDst
+                                     ? boundDst->baseCRS()->getExtensionProj4()
+                                     : targetCRS->getExtensionProj4();
     if (!sourceProj4Ext.empty() || !targetProj4Ext.empty()) {
 
         auto sourceProjExportable =
-            dynamic_cast<io::IPROJStringExportable *>(sourceCRS.get());
+            dynamic_cast<const io::IPROJStringExportable *>(
+                boundSrc ? boundSrc : sourceCRS.get());
         auto targetProjExportable =
-            dynamic_cast<io::IPROJStringExportable *>(targetCRS.get());
+            dynamic_cast<const io::IPROJStringExportable *>(
+                boundDst ? boundDst : targetCRS.get());
         if (!sourceProjExportable) {
             throw InvalidOperation("Source CRS is not PROJ exportable");
         }
@@ -12284,7 +12293,6 @@ CoordinateOperationFactory::Private::createOperations(
         return applyInverse(createOperations(targetCRS, sourceCRS, context));
     }
 
-    auto boundSrc = dynamic_cast<const crs::BoundCRS *>(sourceCRS.get());
     auto geogDst = dynamic_cast<const crs::GeographicCRS *>(targetCRS.get());
     if (boundSrc && geogDst) {
         const auto &hubSrc = boundSrc->hubCRS();
@@ -12474,7 +12482,6 @@ CoordinateOperationFactory::Private::createOperations(
     }
 
     // reverse of previous case
-    auto boundDst = dynamic_cast<const crs::BoundCRS *>(targetCRS.get());
     auto geogSrc = dynamic_cast<const crs::GeographicCRS *>(sourceCRS.get());
     if (geogSrc && boundDst) {
         return applyInverse(createOperations(targetCRS, sourceCRS, context));
diff --git a/test/unit/test_operation.cpp b/test/unit/test_operation.cpp
index 89edfca485..8344ed6ad5 100644
--- a/test/unit/test_operation.cpp
+++ b/test/unit/test_operation.cpp
@@ -7187,6 +7187,30 @@ TEST(operation,
 
 // ---------------------------------------------------------------------------
 
+TEST(
+    operation,
+    createOperation_fallback_to_proj4_strings_regular_to_projliteral_with_towgs84) {
+    auto objSrc =
+        createFromUserInput("EPSG:4326", DatabaseContext::create(), false);
+    auto src = nn_dynamic_pointer_cast<CRS>(objSrc);
+    ASSERT_TRUE(src != nullptr);
+
+    auto objDst = PROJStringParser().createFromPROJString(
+        "+proj=utm +zone=31 +ellps=GRS80 +towgs84=1,2,3 +over +type=crs");
+    auto dst = nn_dynamic_pointer_cast<CRS>(objDst);
+    ASSERT_TRUE(dst != nullptr);
+
+    auto op = CoordinateOperationFactory::create()->createOperation(
+        NN_CHECK_ASSERT(src), NN_CHECK_ASSERT(dst));
+    ASSERT_TRUE(op != nullptr);
+    EXPECT_EQ(op->exportToPROJString(PROJStringFormatter::create().get()),
+              "+proj=pipeline +step +proj=axisswap +order=2,1 "
+              "+step +proj=unitconvert +xy_in=deg +xy_out=rad "
+              "+step +proj=utm +zone=31 +ellps=GRS80 +towgs84=1,2,3 +over");
+}
+
+// ---------------------------------------------------------------------------
+
 TEST(operation, createOperation_on_crs_with_bound_crs_and_wktext) {
     auto objSrc = PROJStringParser().createFromPROJString(
         "+proj=utm +zone=55 +south +ellps=GRS80 +towgs84=0,0,0,0,0,0,0 "