Clang-Tidy

Clang-Tidy is an open-source static analysis tool for C, C++, and Objective-C, developed as part of the LLVM project. It is designed to provide extensible, easy-to-use diagnostic checks for C++ code, covering a wide range of issues from style violations to potential bugs and security vulnerabilities.

Clang-Tidy integrates seamlessly with the Clang compiler front-end, allowing it to perform deep semantic analysis of the code. It is highly configurable, enabling developers to select specific checks relevant to their project's coding standards, such as those derived from MISRA C++, CERT C++, or internal guidelines.

Its primary purpose is to help developers improve code quality, maintainability, and correctness by identifying and suggesting fixes for problematic code patterns.

Clang-Tidy is highly relevant for functional safety, particularly in domains like automotive (ISO 26262), industrial automation (IEC 61508), and avionics (DO-178C). Its ability to perform static analysis and enforce coding standards directly contributes to the reliability and robustness of safety-critical software.

By systematically identifying issues such as potential null pointer dereferences, uninitialized variables, or violations of secure coding guidelines, Clang-Tidy helps prevent common programming errors that could lead to system malfunctions or hazardous situations. Adhering to strict coding standards—which Clang-Tidy can effectively check—is a foundational element in developing software that meets the stringent requirements for functional safety integrity levels (ASILs or SILs), ultimately reducing the risk of systematic failures.

Clang-Tidy's impact on software tool qualification is significant, particularly as a static analysis tool used in the development and verification of safety-critical software. For tools to be used in a functional safety context, they must undergo a qualification process to demonstrate their suitability and reliability.

Although Clang-Tidy is open-source and not qualified out-of-the-box, it can be integrated into a qualified toolchain through qualification processes or by using a qualification kit that supports compliance.

Adopting Clang-Tidy in safety-critical projects presents several challenges. One key challenge is managing the extensive number of checks Clang-Tidy offers; configuring it to be effective without generating excessive false positives or missing critical issues requires careful calibration and expertise.

Integrating Clang-Tidy into existing complex build systems and continuous integration pipelines can also be intricate. Furthermore, interpreting and addressing the warnings generated by Clang-Tidy, especially for legacy codebases that may not adhere to modern coding standards, can demand significant effort for refactoring or justification of deviations.

For tools used in functional safety, ensuring consistent results across different environments and versions of Clang-Tidy, and documenting its usage and outputs as part of the safety case, adds another layer of complexity.

Clang-Tidy is a valuable tool for enforcing coding standards such as MISRA C++ and AUTOSAR C++14, which are commonly used to support compliance with functional safety standards like ISO 26262. While ISO 26262 does not mandate specific tools, it recommends the use of coding guidelines to improve code quality and reduce the risk of software errors. Tools like Clang-Tidy, when properly qualified, can assist in meeting these requirements.

By integrating Clang-Tidy into the development workflow from continuous integration pipelines to developer workstations, organizations can ensure that code consistently adheres to the required safety-critical coding standards throughout the software development lifecycle. This significantly contributes to the overall functional safety argument and reduces the effort required for manual code reviews.