Shift record type value for IndexRefId hash

apps/openmw_test_suite/esm/testrefid.cpp

@@ -196,6 +196,22 @@ namespace ESM
             EXPECT_NE(stringRefId, formIdRefId);
         }
 
+        TEST(ESMRefIdTest, indexRefIdHashDiffersForDistinctValues)
+        {
+            const RefId a = RefId::index(static_cast<RecNameInts>(3), 1);
+            const RefId b = RefId::index(static_cast<RecNameInts>(3), 2);
+            std::hash<RefId> hash;
+            EXPECT_NE(hash(a), hash(b));
+        }
+
+        TEST(ESMRefIdTest, indexRefIdHashDiffersForDistinctRecords)
+        {
+            const RefId a = RefId::index(static_cast<RecNameInts>(1), 3);
+            const RefId b = RefId::index(static_cast<RecNameInts>(2), 3);
+            std::hash<RefId> hash;
+            EXPECT_NE(hash(a), hash(b));
+        }
+
         struct ESMRefIdToStringTest : TestWithParam<std::pair<RefId, std::string>>
         {
         };

components/esm/indexrefid.hpp

@@ -53,7 +53,7 @@ namespace std
     {
         std::size_t operator()(ESM::IndexRefId value) const noexcept
         {
-            return std::hash<std::uint64_t>{}(static_cast<std::uint64_t>(value.mRecordType) | value.mValue);
+            return std::hash<std::uint64_t>{}((static_cast<std::uint64_t>(value.mRecordType) << 32) | value.mValue);
         }
     };
 }