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Allowing too many objects to have external linkage can use up descriptive identifiers, leading to more complicated identifiers, violations of abstraction models, and possible name conflicts with libraries. If the compilation unit implements a data abstraction, it may also expose invocations of private functions from outside the abstraction.
Recommendation | Severity | Likelihood | Remediation Cost | Priority | Level |
|---|---|---|---|---|---|
DCL15-C | Low | Unlikely | Low | P3 | L3 |
Automated Detection
Tool | Version | Checker | Description | ||||||
|---|---|---|---|---|---|---|---|---|---|
| Astrée |
| global-object-scope | Fully checked | ||||||
| Axivion Bauhaus Suite |
| CertC-DCL15 | |||||||
| CodeSonar |
| LANG.STRUCT.SCOPE.FILE | Scope could be file static | ||||||
| CC2.DCL15 | Fully implemented | |||||||
| Helix QAC |
| C1504, C1531 | |||||||
| LDRA tool suite |
| 27 D | Fully implemented | ||||||
| Parasoft C/C++test |
1504
1531
| CERT_C-DCL15-a | Objects or functions with external linkage shall be declared in a header file | |||||||
| PC-lint Plus |
| 765 | Fully supported | ||||||
| Polyspace Bug Finder |
| Checks for situations where function or object with external linkage is referenced in only one translation unit (rec. fully covered) | |||||||
| RuleChecker |
| global-object-scope | Fully checked |
| Splint |
|
Related Vulnerabilities
Search for vulnerabilities resulting from the violation of this rule on the CERT website.
Related Guidelines
| SEI CERT C++ Coding Standard | VOID DCL15-CPP. Declare file-scope objects or functions that do not need external linkage in an unnamed namespace |
| MISRA C:2012 | Rule 8.7 (advisory) |
Bibliography
| ISO/IEC 9899:2011 | Subclause 6.2.2, "Linkages of Identifiers" |
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