MISRA C:2023 Rule 4.2

Rule Definition

Trigraphs should not be used.

Rationale

You denote trigraphs with two question marks followed by a specific third character (for instance,'??-' represents a '~' (tilde) character and '??)' represents a ']'). These trigraphs can cause accidental confusion with other uses of two question marks.

Polyspace Implementation

The Polyspace^® analysis converts trigraphs to the equivalent character for the defect analysis. However, Polyspace also raises a MISRA™ violation.

The standard requires that trigraphs must be transformed before comments are removed during preprocessing. Therefore, Polyspace raises a violation of this rule even if a trigraph appears in code comments.

Troubleshooting

If you expect a rule violation but do not see it, refer to Diagnose Why Coding Standard Violations Do Not Appear as Expected.