MISRA C:2012 Rule 3.1

int x;
int y;
int z;

void non_compliant_comments ( void )
{
    x = y //  	/* Non-compliant
        + z
        //  */
        ;
    z++;	//	Compliant with exception: // permitted within a // comment
}

void compliant_comments ( void )
{
    x = y /*  	Compliant
      + z
	  */
        ;
    z++;	//	Compliant with exception: // is permitted within a // comment
}

In this example, in the non_compliant_comments function, the /* character occurs in what appears to be a // comment, violating the rule. Because of the comment structure, the operation that takes place is x = y + z;. However, without the two //-s, an entirely different operation x=y; takes place. It is not clear which operation is intended.

Use a comment format that makes your intention clear. For instance, in the compliant_comments function, it is clear that the operation x=y; is intended.