STRONG.TYPE.JOIN.CMP

Comparison of different strong types

The STRONG.TYPE family of checkers detects situations in which programmer-enforced strong typing (type-defined abstract types) is broken or ignored, allowing the underlying ANSI type semantics to dominate.

The STRONG.TYPE.JOIN.CMP checker looks for an instance in which two different strong type values are compared using the >, ≥, <, or ≤ operator.

Vulnerability and risk

A compiler following the ANSI standard won't report a warning for this sort of issue, as it checks only the underlying types, not the surface, or programmer-defined, types. As a result, it's possible that a logic error can occur.

Vulnerable code example

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 typedef int Count;
 typedef int Weight;

 int main() {
   Weight w;
   Count c;
   if (w >= c) ;
   return 0;
 }

Klocwork flags line 7, indicating that values of different strong types, Count and Weight, are compared with the >= operator.

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