From bd10becb6540543c94f902ff1fe1dff8f35dd9eb Mon Sep 17 00:00:00 2001
From: elsid <elsid.mail@gmail.com>
Date: Sat, 8 Apr 2023 16:20:50 +0200
Subject: [PATCH] Use lexicographical comparison in
 ESM3ExteriorCellRefId::operator<

---
 apps/openmw_test_suite/esm/testrefid.cpp | 8 ++++++++
 components/esm/esm3exteriorcellrefid.hpp | 9 +++++++--
 2 files changed, 15 insertions(+), 2 deletions(-)

diff --git a/apps/openmw_test_suite/esm/testrefid.cpp b/apps/openmw_test_suite/esm/testrefid.cpp
index 19aa0d5d13..65fe27605c 100644
--- a/apps/openmw_test_suite/esm/testrefid.cpp
+++ b/apps/openmw_test_suite/esm/testrefid.cpp
@@ -212,6 +212,14 @@ namespace ESM
             EXPECT_NE(hash(a), hash(b));
         }
 
+        TEST(ESMRefIdTest, esm3ExteriorCellHasLexicographicalOrder)
+        {
+            const RefId a = RefId::esm3ExteriorCell(0, 0);
+            const RefId b = RefId::esm3ExteriorCell(1, 0);
+            EXPECT_LT(a, b);
+            EXPECT_TRUE(!(b < a));
+        }
+
         struct ESMRefIdToStringTest : TestWithParam<std::pair<RefId, std::string>>
         {
         };
diff --git a/components/esm/esm3exteriorcellrefid.hpp b/components/esm/esm3exteriorcellrefid.hpp
index 9bb9bf17d8..5fca8dc597 100644
--- a/components/esm/esm3exteriorcellrefid.hpp
+++ b/components/esm/esm3exteriorcellrefid.hpp
@@ -28,9 +28,14 @@ namespace ESM
         int32_t getX() const { return mX; }
         int32_t getY() const { return mY; }
 
-        constexpr bool operator==(ESM3ExteriorCellRefId rhs) const noexcept { return mX == rhs.mX && mY == rhs.mY; }
+        friend inline constexpr auto tie(const ESM3ExteriorCellRefId& value) noexcept
+        {
+            return std::tie(value.mX, value.mY);
+        }
+
+        constexpr bool operator==(ESM3ExteriorCellRefId rhs) const noexcept { return tie(*this) == tie(rhs); }
 
-        constexpr bool operator<(ESM3ExteriorCellRefId rhs) const noexcept { return mX < rhs.mX && mY < rhs.mY; }
+        constexpr bool operator<(ESM3ExteriorCellRefId rhs) const noexcept { return tie(*this) < tie(rhs); }
 
         friend std::ostream& operator<<(std::ostream& stream, ESM3ExteriorCellRefId value);