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Some identifiers are reserved.
— All identifiers that begin with a double underscore (__) or begin with an underscore (_) followed by an uppercase letter are reserved for any use, except those identifiers which are lexically identical to keywords.
— All identifiers that begin with an underscore are reserved for use as identifiers with file scope in both the ordinary and tag name spaces.
Other identifiers may be reserved, see 7.1.3.
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Each header declares or defines all identifiers listed in its associated subclause, and optionally declares or defines identifiers listed in its associated future library directions subclause and identifiers which are always reserved either for any use or for use as file scope identifiers.
— All potentially reserved identifiers (including ones listed in the future library directions) that are provided by an implementation with an external definition are reserved for any use. An implementation shall not provide an external definition of a potentially reserved identifier unless that identifier is reserved for a use where it would have external linkage. All other potentially reserved identifiers that are provided by an implementation (including in the form of a macro) are reserved for any use when the associated header is included. No other potentially reserved identifiers are reserved.
— Each macro name in any of the following subclauses (including the future library directions) is reserved for use as specified if any of its associated headers is included; unless explicitly stated otherwise (see 7.1.4).
— All identifiers with external linkage in any of the following subclauses (including the future library directions) and
errnoare always reserved for use as identifiers with external linkage.— Each identifier with file scope listed in any of the following subclauses (including the future library directions) is reserved for use as a macro name and as an identifier with file scope in the same name space if any of its associated headers is included.
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Using reserved identifiers can lead to incorrect program operation.
Rule | Severity | Likelihood | Detectable | RepairableRemediation Cost | Priority | Level |
|---|---|---|---|---|---|---|
DCL37-C | Low | Unlikely | Yes | NoLow | P3P2 | L3 |
Automated Detection
Tool | Version | Checker | Description | ||||||
|---|---|---|---|---|---|---|---|---|---|
| Astrée |
| future-library-use language-override language-override-c99 reserved-declaration reserved-declaration-c99 reserved-identifier | Partially checked | ||||||
| Axivion Bauhaus Suite |
| CertC-DCL37 | Fully implemented. Reserved identifiers, as in DCL37-C-EX3, are configurable. | ||||||
| CodeSonar |
| LANG.STRUCT.DECL.RESERVED | Declaration of reserved name | ||||||
| Compass/ROSE | |||||||||
| Coverity |
| MISRA C 2004 Rule 20.1 MISRA C 2004 Rule 20.2 MISRA C 2012 Rule 21.1 MISRA C 2012 Rule 21.2 | Implemented | ||||||
| Cppcheck Premium |
| premium-cert-dcl37-c | |||||||
| ECLAIR |
| CC2.DCL37 | Fully implemented | ||||||
| Helix QAC |
| C0602, C0603, C4600, C4601, C4602, C4603, C4604, C4605, C4606, C4607, C4608, C4620, C4621, C4622, C4623, C4624, C4640, C4641, C4642, C4643, C4644, C4645 | Fully implemented | ||||||
| Klocwork |
| MISRA.DEFINE.WRONGNAME.UNDERSCORE MISRA.STDLIB.WRONGNAME.UNDERSCORE MISRA.STDLIB.WRONGNAME | Fully implemented | ||||||
| LDRA tool suite |
| 86 S, 218 S, 219 S, 580 S, 626 S | Fully Implemented | ||||||
| Parasoft C/C++test |
| CERT_C-DCL37-b | Identifiers that begin with an underscore and either an uppercase letter or another underscore should not be declared Avoid declaring file-scoped objects whose names begin with an underscore The names of standard library macros should not be reused (C11 code) The names of standard library identifiers with file scope should not be reused (C11 code) The standard library identifiers with external linkage should not be reused (C11 code) Macros that begin with an underscore and either an uppercase letter or another underscore should not be defined | ||||||
| PC-lint Plus |
| 978, 9071, 9093 | Partially supported | ||||||
| Polyspace Bug Finder |
| Checks for:
Rule partially covered | |||||||
| PVS-Studio |
| V677 | |||||||
| SonarQube C/C++ Plugin |
| S978 | |||||||
| RuleChecker |
| future-library-use language-override language-override-c99 reserved-declaration reserved-declaration-c99 reserved-identifier | Partially checked |
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