Awareness and Experience of Developers to Outdated and License-Violating Code on Stack Overflow: An Online Survey

We performed two online surveys of Stack Overflow answerers and visitors to assess their awareness to outdated code and software licenses in Stack Overflow answerers. The answerer survey targeted 607 highly reputed Stack Overflow users and received a high response rate of 33%. Our findings are as follows. Although most of the code snippets in the answers are written from scratch, there are code snippets cloned from the corresponding questions, from personal or company projects, or from open source projects. Stack Overflow answerers are aware that some of their snippets are outdated. However, 19% of the participants report that they rarely or never fix their outdated code. At least 98% of the answerers never include software licenses in their snippets and 69% never check for licensing conflicts with Stack Overflow's CC BY-SA 3.0 if they copy the code from other sources to Stack Overflow answers. The visitor survey uses convenient sampling and received 89 responses. We found that 66% of the participants experienced a problem from cloning and reusing Stack Overflow snippets. Fifty-six percent of the visitors never reported the problems back to the Stack Overflow post. Eighty-five percent of the participants are not aware that StackOverflow applies the CC BY-SA 3.0 license, and sixty-two percent never give attributions to Stack Overflow posts or answers they copied the code from. Moreover, 66% of the participants do not check for licensing conflicts between the copied Stack Overflow code and their software. With these findings, we suggest Stack Overflow raise awareness of their users, both answerers and visitors, to the problem of outdated and license-violating code snippets.