Which of the following are the typical defects found by static analysis tools?

Static analysis tools are designed to analyze source code without executing it. Their primary purpose is to identify structural and syntactic issues that could lead to defects or inefficiencies in the software.

Unreachable code is a classic example of a defect that static analysis tools often detect. This type of code is written but never executed during the program's runtime, which can lead to unnecessary code complexity and maintenance challenges. Detecting unreachable code helps developers clean up their codebases, improving readability and maintainability.

Variables that are never used can also be identified by static analysis tools, as well as security vulnerabilities and potential performance issues. However, while these other types of issues can indeed be uncovered through static analysis, unreachable code distinctly emphasizes the structural integrity of the codebase, focusing specifically on logic flow and code execution paths, making it a more explicit defect targeted by such tools.