Fix uint64 vector unit tests

Firebird and SQLite store UINT64_MAX incorrectly, leading to an incorrect
value ordering when retrieving sorted table contents.

tests/common-tests.h

@@ -466,6 +466,11 @@ public:
     // strings (Oracle does this).
     virtual bool treats_empty_strings_as_null() const { return false; }
 
+    // Override this if the backend does not store values bigger than INT64_MAX
+    // correctly. This can lead to an unexpected ordering of values as larger
+    // values might be stored as overflown and therefore negative integer.
+    virtual bool has_uint64_storage_bug() const { return false; }
+
     // Override this to call commit() if it's necessary for the DDL statements
     // to be taken into account (currently this is only the case for Firebird).
     virtual void on_after_ddl(session&) const { }
@@ -2406,12 +2411,24 @@ TEST_CASE_METHOD(common_tests, "Use vector", "[core][use][vector]")
 
         sql << "select ul from soci_test order by ul", into(v2);
         CHECK(v2.size() == 6);
-        CHECK(v2[0] == (std::numeric_limits<uint64_t>::min)());
-        CHECK(v2[1] == 0);
-        CHECK(v2[2] == 1);
-        CHECK(v2[3] == 123);
-        CHECK(v2[4] == 1000);
-        CHECK(v2[5] == (std::numeric_limits<uint64_t>::max)());
+        if (tc_.has_uint64_storage_bug())
+        {
+            CHECK(v2[0] == (std::numeric_limits<uint64_t>::max)());
+            CHECK(v2[1] == (std::numeric_limits<uint64_t>::min)());
+            CHECK(v2[2] == 0);
+            CHECK(v2[3] == 1);
+            CHECK(v2[4] == 123);
+            CHECK(v2[5] == 1000);
+        }
+        else
+        {
+            CHECK(v2[0] == (std::numeric_limits<uint64_t>::min)());
+            CHECK(v2[1] == 0);
+            CHECK(v2[2] == 1);
+            CHECK(v2[3] == 123);
+            CHECK(v2[4] == 1000);
+            CHECK(v2[5] == (std::numeric_limits<uint64_t>::max)());
+        }
     }
 
     SECTION("double")

tests/firebird/test-firebird.cpp

@@ -1339,6 +1339,17 @@ class test_context : public tests::test_context_base
             return "'" + datdt_string + "'";
         }
 
+        bool has_uint64_storage_bug() const override
+        {
+            // Firebird does not support unsigned integer types.
+            // We're using Firebird 3, which does not yet support a data
+            // type that can correctly store a UINT64_MAX. The biggest
+            // numeric data type available is numeric(18,0).
+            // Firebird 4 introduces the data type int128 and numeric(36,0),
+            // which will be sufficient for that in the future.
+            return true;
+        }
+
         void on_after_ddl(soci::session& sql) const override
         {
             sql.commit();

tests/sqlite3/test-sqlite3.cpp

@@ -665,6 +665,13 @@ public:
         return true;
     }
 
+    bool has_uint64_storage_bug() const override
+    {
+        // SQLite processes integers as 8-byte signed values. Values bigger
+        // than INT64_MAX therefore overflow and are stored as negative values.
+        return true;
+    }
+
     bool enable_std_char_padding(soci::session&) const override
     {
         // SQLite does not support right padded char type.