0556			[C] Left operand of assignment must be a modifiable object.
	Constraint violations				REFERENCE - ISO:C90-6.3.16 Assignment Operators - Constraints

/*PRQA S 3132,3227,3313,3408,3447,3602,3617 ++*/

extern struct ST stx;       /* ST is incomplete type */
extern struct ST sty;

extern int lbuf[10];
extern const int ci;

void foo(int mode)
{
    lbuf = mode;            /* Message 0556 and also 0555 */
    ci = mode;              /* Message 0556               */
    stx = sty;              /* Message 0556 and also 0545 */
}

See also:

• 0545 [U] The value of an incomplete 'struct' may not be used.
• 0555 [C] Invalid assignment to object of void type or array type.