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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.

#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.

Automated Detection

Related Vulnerabilities

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

Related Guidelines

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