Keep a memory of how to trigger #583 error

Tests/GRDBTests/DatabaseCursorTests.swift

@@ -128,5 +128,46 @@ class DatabaseCursorTests: GRDBTestCase {
                     User(username: flagged.username)
             }
         }
+
+        // For the record, the lines below show how this test used to fail,
+        // with raw C SQLite3 apis. The faulty line is the call to
+        // sqlite3_set_authorizer during the statement iteration.
+
+//        if #available(OSX 10.14, *) {
+//            var connection: SQLiteConnection? = nil
+//            sqlite3_open_v2(":memory:", &connection, SQLITE_OPEN_READWRITE | SQLITE_OPEN_NOMUTEX, nil)
+//            sqlite3_extended_result_codes(connection, 1)
+//
+//            sqlite3_exec(connection, """
+//                 CREATE TABLE user (username TEXT NOT NULL);
+//                 CREATE TABLE flagUser (username TEXT NOT NULL);
+//                 INSERT INTO flagUser (username) VALUES ('User1');
+//                 INSERT INTO flagUser (username) VALUES ('User2');
+//                 """, nil, nil, nil)
+//
+//            var statement: SQLiteStatement? = nil
+//            sqlite3_set_authorizer(connection, { (_, _, _, _, _, _) in SQLITE_OK }, nil)
+//            sqlite3_prepare_v3(connection, """
+//                 SELECT * FROM flagUser WHERE (SELECT COUNT(*) FROM user WHERE username = flagUser.username) = 0
+//                 """, -1, 0, &statement, nil)
+//            sqlite3_set_authorizer(connection, nil, nil)
+//            while true {
+//                let code = sqlite3_step(statement)
+//                if code == SQLITE_DONE {
+//                    break
+//                } else if code == SQLITE_ROW {
+//                    // part of the compilation of another statement, here
+//                    // reduced to the strict minimum that reproduces
+//                    // the error.
+//                    sqlite3_set_authorizer(connection, nil, nil)
+//                } else {
+//                    print(String(cString: sqlite3_errmsg(connection)))
+//                    XCTFail("Error \(code)")
+//                    break
+//                }
+//            }
+//            sqlite3_finalize(statement)
+//            sqlite3_close_v2(connection)
+//        }
     }
 }