From 626bf0fc4587f70bd15ab585f58d026ff2b555cd Mon Sep 17 00:00:00 2001
From: Adam Kewley <contact@adamkewley.com>
Date: Mon, 29 Jul 2024 15:51:12 +0200
Subject: [PATCH] Fix UB found by libASAN build

---
 src/oscar/Graphics/GraphicsImplementation.cpp | 10 ++++++++--
 tests/testoscar/Graphics/TestMesh.cpp         | 18 ++++++++++++++++++
 2 files changed, 26 insertions(+), 2 deletions(-)

diff --git a/src/oscar/Graphics/GraphicsImplementation.cpp b/src/oscar/Graphics/GraphicsImplementation.cpp
index 2d68e4ccb5..21c2dfd8a4 100644
--- a/src/oscar/Graphics/GraphicsImplementation.cpp
+++ b/src/oscar/Graphics/GraphicsImplementation.cpp
@@ -4923,8 +4923,14 @@ class osc::Mesh::Impl final {
     {
         indices_are_32bit_ = false;
         num_indices_ = indices.size();
-        indices_data_.resize((indices.size()+1)/2);
-        rgs::copy(indices, &indices_data_.front().u16.a);
+
+        if (not indices.empty()) {
+            indices_data_.resize((indices.size()+1)/2);
+            rgs::copy(indices, &indices_data_.front().u16.a);
+        }
+        else {
+            indices_data_.clear();
+        }
 
         range_check_indices_and_recalculate_bounds(flags);
         version_->reset();
diff --git a/tests/testoscar/Graphics/TestMesh.cpp b/tests/testoscar/Graphics/TestMesh.cpp
index 83bcebff92..b6199afdfd 100644
--- a/tests/testoscar/Graphics/TestMesh.cpp
+++ b/tests/testoscar/Graphics/TestMesh.cpp
@@ -809,6 +809,24 @@ TEST(Mesh, SetIndicesThrowsIfOutOfBounds)
     ASSERT_ANY_THROW({ m.set_indices(iota_index_range(3, 6)); }) << "should throw: indices are out-of-bounds";
 }
 
+TEST(Mesh, SetIndices16BitWorksWithEmptyVector)
+{
+    std::vector<uint16_t> indices;
+    Mesh m;
+    m.set_vertices(generate_vertices(3));
+    m.set_indices(indices);  // should just work
+    ASSERT_TRUE(m.indices().empty());
+}
+
+TEST(Mesh, SetIndices32BitWorksWithEmptyVector)
+{
+    std::vector<uint32_t> indices;
+    Mesh m;
+    m.set_vertices(generate_vertices(3));
+    m.set_indices(indices);  // should just work
+    ASSERT_TRUE(m.indices().empty());
+}
+
 TEST(Mesh, SetIndiciesWithDontValidateIndicesAndDontRecalculateBounds)
 {
     Mesh m;