Code Cloning in Solidity Smart Contracts: Prevalence, Evolution, and Impact on Development

In recent years, the development of Solidity smart contracts has been increasing rapidly in popularity. Code cloning is a common coding practice, and many prior studies have revealed that code clones could negatively impact software maintenance and quality. However, there is little work systematically analyzing the nature and impacts of code clones in solidity smart contracts. To bridge this gap, we investigate the prevalence, evolution, and bug-proneness of code clones in solidity smart contracts, and further identify the possible reasons for these clones' occurrences. With our evaluation of 26,294 smart contracts with 97,877 functions, we have found that code clones are highly prevalent in smart contracts. Additionally, on average, 32.01% of clones co-evolve, indicating the need for careful management to avoid consistency issues. Surprisingly, unlike in traditional software development, code clones in smart contracts are rarely involved in bug fixes. Finally, we identify three main factors that affect the occurrences of clones. We believe our study can provide valuable insights for developers to understand and manage code clones in solidity smart contracts.