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DCL01-C-EX2: A temporary variable within a new scope inside of a macro can override a surrounding identifier.override an identifier in a containing scope. However,this exception does not apply to to the arguments of the macro itself.

Code Block

bgColor	#ccccff
lang	c

#define SWAP(type, a, b) do { type tmp = a; a = b; b = tmp; } while(0)
 
void func(void) {
  int tmp = 100;
  int a = 10, b = 20;
  SWAP(int, a, b); /* Hidden redeclaration of tmp is acceptable */
  SWAP(int, tmp, b); /* NONCOMPLIANT: Hidden redeclaration of tmp clashes with argument */
}

Risk Assessment

Reusing a variable name in a subscope can lead to unintentionally referencing an incorrect variable.

Recommendation	Severity	Likelihood	Detectable	Remediation CostRepairable	Priority	Level
DCL01-C	Low	Unlikely	Yes	YesMedium	P2P3	L3

Automated Detection

Variable shadowing

MISRA 2012 Rule 5.3

Tool

Version

Checker

Description

Astrée

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	Astrée_V
	Astrée_V

Supported indirectly via MISRA C:2012 Rule 5.3.

Axivion Bauhaus Suite

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	Axivion Bauhaus Suite_V
	Axivion Bauhaus Suite_V

CertC-DCL01

CodeSonar

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	CodeSonar_V
	CodeSonar_V

LANG.ID.ND.NEST

Non-distinct identifiers: nested scope

Compass/ROSE

ECLAIR

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	ECLAIR_V
	ECLAIR_V

CC2.DCL01

Fully implemented

Helix QAC

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	Helix QAC_V
	Helix QAC_V

C0795, C0796, C2547, C3334

Klocwork

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	Klocwork_V
	Klocwork_V

MISRA.VAR.HIDDEN

LDRA tool suite

Include Page

	LDRA_V
	LDRA_V

131 S

Fully implemented

Parasoft C/C++test

Include Page

	Parasoft_V
	Parasoft_V

CERT_C-DCL01-a
CERT_C-DCL01-b

Identifier declared in a local or function prototype scope shall not hide an identifier declared in a global or namespace scope
Identifiers declared in an inner local scope should not hide identifiers declared in an outer local scope

PC-lint Plus

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