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The C Standard, 5.1.1.2, paragraph 4 [ISO/IEC 9899:20112024], says
If a character sequence that matches the syntax of a universal character name is produced by token concatenation (6.10.35.3), the behavior is undefined.
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Creating a universal character name through token concatenation results in undefined behavior. See undefined behavior 3.
Rule | Severity | Likelihood | Detectable | Remediation CostRepairable | Priority | Level |
|---|---|---|---|---|---|---|
PRE30-C | Low | Unlikely | Yes | NoMedium | P2 | L3 |
Automated Detection
Tool | Version | Checker | Description | ||||||||||||
|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|
| Astrée |
| universal-character-name-concatenation | Fully implemented | ||||||||||||
| CertC-PRE30 | Fully implemented | |||||||||||||
| CodeSonar |
| LANG.PREPROC.PASTE LANG.PREPROC.PASTEHASH | Macro uses ## operator## follows # operator | ||||||||||||
| Cppcheck | 2.15.0 | preprocessorErrorDirective |
| preprocessorErrorDirective | |||||||||||
| Cppcheck Premium |
| 24.9.0 | preprocessorErrorDirective |
| preprocessorErrorDirectiveFully implemented | ||||||||||
| Helix QAC |
| C0905 C++0064,C++0080 | Fully implemented | ||||||||||||
| Klocwork |
| MISRA.DEFINE.SHARP | Fully implemented | ||||||||||||
| LDRA tool suite |
| 573 S | Fully implemented | ||||||||||||
| Parasoft C/C++test |
| CERT_C-PRE30-a | Avoid token concatenation that may produce universal character names | ||||||||||||
| CERT C: Rule PRE30-C | Checks for universal character name from token concatenation (rule fully covered) | |||||||||||||
| RuleChecker |
| universal-character-name-concatenation | Fully checked |
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| [ISO/IEC 10646-2003] | |
| [ISO/IEC 9899:20112024] | Subclause 5.1.1.2, "Translation Phases" |
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