MISRA.BITS.NOT_UNSIGNED.PREP

Rule 5-0-21: Bitwise operators shall only be applied to operands of unsigned underlying type

Operand of bitwise operation in a preprocessor directive #if or #elif is not an unsigned integer

Rationale

Rationale Bitwise operations (~, <<, <<=, >>, >>=, &, &=, ^, ^=, | and |=) are not normally meaningful on signed integers or enumeration constants. Additionally, an implementation-defined result is obtained if a right shift is applied to a negative value.

Example

if ( ( uint16_a & int16_b ) == 0x1234U )   // Non-compliant 
if ( ( uint16_a | uint16_b ) == 0x1234U )  // Compliant 
if ( ~int16_a == 0x1234U )                 // Non-compliant 
if ( ~uint16_a == 0x1234U )                // Compliant