From a48a69e1923dfb18a95a477a89d1d4c4a0adde47 Mon Sep 17 00:00:00 2001
From: Javier Jimenez Shaw <j1@jimenezshaw.com>
Date: Wed, 14 Sep 2022 23:50:09 +0200
Subject: [PATCH] implement alterCSLinearUnit for CompoundCRS

---
 src/iso19111/crs.cpp   | 12 ++++++++++++
 test/unit/test_crs.cpp | 18 ++++++++++++++++--
 2 files changed, 28 insertions(+), 2 deletions(-)

diff --git a/src/iso19111/crs.cpp b/src/iso19111/crs.cpp
index 983ee1f9d8..5bb99969f8 100644
--- a/src/iso19111/crs.cpp
+++ b/src/iso19111/crs.cpp
@@ -378,6 +378,18 @@ CRSNNPtr CRS::alterCSLinearUnit(const common::UnitOfMeasure &unit) const {
         }
     }
 
+    {
+        auto compoundCRS = dynamic_cast<const CompoundCRS *>(this);
+        if (compoundCRS) {
+            std::vector<CRSNNPtr> components;
+            for (const auto &subCrs :
+                 compoundCRS->componentReferenceSystems()) {
+                components.push_back(subCrs->alterCSLinearUnit(unit));
+            }
+            return CompoundCRS::create(createPropertyMap(this), components);
+        }
+    }
+
     return NN_NO_CHECK(
         std::dynamic_pointer_cast<CRS>(shared_from_this().as_nullable()));
 }
diff --git a/test/unit/test_crs.cpp b/test/unit/test_crs.cpp
index 7928270858..f38fe3c657 100644
--- a/test/unit/test_crs.cpp
+++ b/test/unit/test_crs.cpp
@@ -6551,11 +6551,25 @@ TEST(crs, crs_alterCSLinearUnit) {
     }
 
     {
-        // Not implemented on compoundCRS
         auto crs =
             createCompoundCRS()->alterCSLinearUnit(UnitOfMeasure("my unit", 2));
-        EXPECT_TRUE(createCompoundCRS()->isEquivalentTo(crs.get()));
+        auto compoundCRS = dynamic_cast<CompoundCRS *>(crs.get());
+        ASSERT_TRUE(compoundCRS != nullptr);
+        EXPECT_EQ(compoundCRS->componentReferenceSystems().size(), 2U);
+        for (const auto &subCrs : compoundCRS->componentReferenceSystems()) {
+            auto singleCrs = dynamic_cast<SingleCRS *>(subCrs.get());
+            ASSERT_TRUE(singleCrs != nullptr);
+            auto cs = singleCrs->coordinateSystem();
+            ASSERT_GE(cs->axisList().size(), 1U);
+            EXPECT_EQ(cs->axisList()[0]->unit().name(), "my unit");
+            EXPECT_EQ(cs->axisList()[0]->unit().conversionToSI(), 2);
+        }
     }
+
+    // Not implemented on parametricCRS
+    auto crs =
+        createParametricCRS()->alterCSLinearUnit(UnitOfMeasure("my unit", 2));
+    EXPECT_TRUE(createParametricCRS()->isEquivalentTo(crs.get()));
 }
 
 // ---------------------------------------------------------------------------