Software Coding Guidelines

ISO 26262-6 requires that safety-related software be written using modelling and coding guidelines that address defined criteria - enforcement of low complexity, use of language subsets, strong typing, defensive implementation techniques, and similar topics listed in the standard. The standard names criteria, not a specific rule set; in practice the industry meets them with established standards: MISRA C:2012 for C, MISRA C++:2008 or AUTOSAR C++14 for C++, and CERT C for security-oriented concerns. A compliant setup combines a selected and tailored rule set, tool-based enforcement through static analysis, a formal deviation process for justified violations, and compliance evidence for the safety assessment.

No - ISO 26262 never names MISRA. It requires coding guidelines that cover the standard's criteria, such as language subsets and low complexity, and leaves the choice of rule set to the project. MISRA C:2012, with its 143 rules and 16 directives classified as mandatory, required, or advisory, is simply the de facto way to satisfy those criteria for C. Claiming compliance with a recognized standard is far easier to defend at assessment than a homegrown guideline document, which is why nearly every automotive project uses MISRA or a MISRA-derived set.

A deviation is a documented, justified decision to violate a specific guideline rule at a specific location - the pressure valve that keeps a rule set enforceable. A compliant deviation record identifies the rule and code location, explains why compliance is not reasonable there, assesses the safety impact, and names alternative measures that address the rule's underlying risk. Deviations need review and approval, not just a suppression comment. In the course's engine-control case study, 47 justified deviations from mandatory rules were processed this way and accepted at assessment.

MISRA C targets safety: it constrains C to a predictable subset by banning constructs with undefined or implementation-defined behaviour that make code unanalyzable. CERT C targets security: its rules address exploitable weaknesses and are categorized by severity and likelihood. The overlap is substantial - buffer overflows and integer overflows are both safety and security problems - so the two complement each other, and with ISO 21434 pushing cybersecurity into automotive projects, many teams now enforce MISRA C as the base with safety-relevant CERT C rules layered on top.

Fifteen chapters spanning 400+ rules across MISRA C:2012, MISRA C++:2008, AUTOSAR C++14, and CERT C, plus rule selection and tailoring, static analysis tooling, deviation management, and dedicated chapters on memory safety, timing, numeric safety, and concurrency. The case study takes a 45,000-line ASIL C engine control codebase from 2,400 initial violations to an assessment-ready compliance package. A free account starts you off, and the Pro and Expert plans unlock more of the library.