Rule Definition
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.

Remediation
Try splitting the expressions and assignments into multiple lines for better readability and maintainability.

Violation Code Sample

x = y;
x = y = z; // Non-compliant


if ( ( x = y ) != 0 ) // Non-compliant
{
foo ( );
}
if ( x = y ) // Non-compliant
{
foo ( );
}

Fixed Code Sample

if ( x != 0 ) // Compliant
{
foo ( );
}

bool b1 = x != y; // Compliant
bool b2;
b2 = x != y; // Compliant

if ( int16_t i = foo ( ) ) // Compliant
{
)
_________________________
x=y;

if ( x != 0 ) // compliant
{
foo ( );
}

Standards Reference: MISRA C++ 2008, Rule 6–2–1: Assignment operators shall not be used in subexpressions.