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This recommendation is a specific case of MSC12-C. Detect and remove code that has no effect or is never executed.
Noncompliant Code Example
In this example, p2 is assigned the value returned by bar(), but that value is never used. Note this example assumes that foo() and bar() return valid pointers . (See see DCL30-C. Declare objects with appropriate storage durations).)
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int *p1,; int *p2; p1 = foo(); p2 = bar(); if (baz()) { return p1; } else { p2 = p1; } return p2; |
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int *p1 = foo(); /* Removable if bar() does not produce any side effects */ (void)bar(); /* Removable if baz() does not produce any side effects */ (void)baz(); return p1; |
Exceptions
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Risk Assessment
Unused values may indicate significant logic errors.
Recommendation | Severity | Likelihood | Remediation Cost | Priority | Level |
|---|---|---|---|---|---|
MSC13-C |
Low |
Unlikely |
Medium | P2 | L3 |
Automated Detection
Tool | Version | Checker | Description |
|---|
| Astrée |
|
|
|
1 D
70 D
94 D
15 D
Fully implemented.
| Supported, but no explicit checker | |||||||||
| CodeSonar |
| LANG.STRUCT.UUVAL | Unused value | ||||||
| UNUSED_VALUE | Finds variables that are assigned pointer values returned from a function call but never used |
| Helix QAC |
| C1500, C1502, C3203, C3205, C3206, C3207, C3229 DF2980, DF2981, DF2982, DF2983, DF2984, DF2985, DF2986 | |||||||
| Klocwork |
| LV_UNUSED.GEN | |||||||
| LDRA tool suite |
|
1 D, 8 D, 105 D, 94 D, 15 D | Fully implemented | ||||||||
| Parasoft C/C++test |
| CERT_C-MSC13-a | Avoid unnecessary local variables | ||||||
| PC-lint Plus |
| 438, 505, 529, 715, 838 | Partially supported | ||||||
| Polyspace Bug Finder |
| Checks for:
Rec. partially covered. | |||||||
| PVS-Studio |
| V519, V596, V603, V714, V744, V751, V763, V1001, V5003 | |||||||
| SonarQube C/C++ Plugin |
| S1854 |
Related Vulnerabilities
Search for vulnerabilities resulting from the violation of this rule on the CERT website.
Related Guidelines
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| Likely Incorrect Expressions [KOA] Dead and Deactivated Code [XYQ] Unused Variable [XYR] |
Bibliography
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