void inc1(out float x)  { x++; }
void inc4(out float4 x) { x += half4(1); }

void test_a() { inc1(0); }
void test_b() { inc4(float4(0)); }
void test_c() { inc1(sqrt(1)); }

/*%%*
cannot assign to this expression
cannot assign to this expression
cannot assign to this expression
*%%*/