SEI CERT C Coding Standard

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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).)

Code Block
bgColor#FFCCCC
langc
int *p1;
int *p2;
p1 = foo();
p2 = bar();

if (baz()) {
  return p1;
}
else {
  p2 = p1;
}
return p2;

...

Code Block
bgColor#ccccff
langc
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

Anchor
MSC13-EX1
MSC13-EX1
MSC13-EX1: Initializing a variable with a default value, such as 0, which gets subsequently overwritten may be inefficient, but is less of a problem than reading an uninitialized value, as per EXP33-C. Do not read uninitialized memory.

Risk Assessment

Unused values may indicate significant logic errors.

Recommendation

Severity

Likelihood

Detectable

Remediation Cost

Repairable

Priority

Level

MSC13-C

Low

Unlikely

Medium

Yes

Yes

P2

P3

L3

Automated Detection

Tool

Version

Checker

Description

Astrée
Include Page
Astrée_V
Astrée_V

dead-assignment
dead-initializer
unused-local-variable
unused-parameter

Partially checked
CodeSonar
Include Page
CodeSonar_V
CodeSonar_V

LANG.STRUCT.

UVAL

UUVAL

Unused
Value
value

Coverity

Include Page
Coverity_V
Coverity_V

UNUSED_VALUE

Finds variables that are assigned pointer values returned from a function call but never used

Helix QAC

Include Page
Helix QAC_V
Helix QAC_V

C1500, C1502, C3203, C3205, C3206, C3207, C3229

DF2980, DF2981, DF2982, DF2983, DF2984, DF2985, DF2986


Klocwork
Include Page
Klocwork_V
Klocwork_V

 

Can detect violations of this rule with a number of checkers

LV_UNUSED.GEN
VA_UNUSED.GEN
VA_UNUSED.INIT


LDRA tool suite
Include Page
LDRA_V
LDRA_V

1 D


70 D

, 8 D, 105 D, 94 D


, 15 D

Fully implemented

PRQA QA-C

Parasoft C/C++test
Include Page
Parasoft_V
Parasoft_V

CERT_C-MSC13-a

Avoid unnecessary local variables
PC-lint Plus

Include Page

PRQA QA

PC-

C

lint Plus_

v

V

PRQA QA

PC-

C

lint Plus_

v

V

1500

438,

1502

505,

3203

529,

3205,3206,3207,3229,3196, 2980,2981,2982,2983,2984,2985,2986

715, 838

Partially supported

Polyspace Bug Finder

Include Page
Polyspace Bug Finder_V
Polyspace Bug Finder_V

CERT C: Rec. MSC13-C


Checks for:

  • Unused parameter
  • Write without a further read

Rec. partially covered.

PVS-Studio

Include Page
PVS-Studio_V
PVS-Studio_V

V519, V596, V603, V714, V744, V751, V763, V1001, V5003
RuleChecker

Include Page
RuleChecker_V
RuleChecker_V

dead-assignment
dead-initializer
unused-local-variable
unused-parameter		Partially checked
SonarQube C/C++ Plugin
Include Page
SonarQube C/C++ Plugin_V
SonarQube C/C++ Plugin_V
S1854
Fully implemented

Related Vulnerabilities

Search for vulnerabilities resulting from the violation of this rule on the CERT website.

Related Guidelines

SEI CERT C++ Coding StandardVOID MSC13-CPP. Detect and remove unused values
ISO/IEC TR 24772Likely Incorrect Expressions [KOA]
Dead and Deactivated Code [XYQ]
Unused Variable [XYR]

Bibliography

[Coverity 2007]

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