MISRA.CAST.INT.SIGN

Non-trivial integral expression is cast to type with different signedness.

MISRA-C++ Rule 5-0-9 (required): An explicit integral conversion shall not change the signedness of the underlying type of a cvalue expression.

Rationale

A signed to unsigned conversion may lead to an expression having a value inconsistent with developer expectations.

Example

void f ( )
{
   int8_t s8;
   uint8_t u8;

   s8 = static_cast< int8_t >( u8 + u8 );   // Non-compliant
   s8 = static_cast< int8_t >( u8 )
      + static_cast< int8_t >( u8 );        // Compliant
}

In the above example, the expression ( u8 + u8 ) is performed with an underlying type of 'uint8_t' rather than 'int8_t'.