MISRA.ASSIGN.SUBEXPR

Assignment operator is used in sub-expression.

MISRA-C++ Rule 6-2-1 (required): Assignment operators shall not be used in subexpressions.

This rule is also covered by MISRA.ASSIGN.COND.

Rationale

Assignments used in a sub-expression add an additional side effect to that of the full expression, potentially resulting in a value inconsistent with developer expectations. In addition, this helps to avoid getting = and == confused.

Example

x = y;
x = y = z;                 // Non-compliant
if ( x != 0 )              // Compliant
{
   foo ( );
}
bool b1 = x != y;          // Compliant
bool b2;
b2 = x != y;               // Compliant
if ( ( x = y ) != 0 )      // Non-compliant
{
   foo ( );
}
if ( x = y )               // Non-compliant
{
   foo ( );
}
if ( int16_t i = foo ( ) ) // Compliant
{
}