v: allow option array element comparison == and != (fix #23108) (#23113)

vlib/v/checker/infix.v

@@ -897,9 +897,9 @@ fn (mut c Checker) infix_expr(mut node ast.InfixExpr) ast.Type {
 	right_is_option := right_type.has_flag(.option)
 	if left_is_option || right_is_option {
 		opt_infix_pos := if left_is_option { left_pos } else { right_pos }
-		if (node.left !in [ast.Ident, ast.SelectorExpr, ast.ComptimeSelector]
-			|| node.op in [.eq, .ne, .lt, .gt, .le, .ge]) && right_sym.kind != .none
-			&& !c.inside_sql {
+		if (node.left !in [ast.Ident, ast.IndexExpr, ast.SelectorExpr, ast.ComptimeSelector]
+			|| (node.op in [.eq, .ne] && !right_is_option)
+			|| node.op in [.lt, .gt, .le, .ge]) && right_sym.kind != .none && !c.inside_sql {
 			c.error('unwrapped Option cannot be used in an infix expression', opt_infix_pos)
 		}
 	}

vlib/v/gen/c/infix.v

@@ -112,7 +112,9 @@ fn (mut g Gen) infix_expr_eq_op(node ast.InfixExpr) {
 		g.gen_plain_infix_expr(node)
 		return
 	}
-	is_none_check := left_type.has_flag(.option) && node.right is ast.None
+	left_is_option := left_type.has_flag(.option)
+	right_is_option := right_type.has_flag(.option)
+	is_none_check := left_is_option && node.right is ast.None
 	if is_none_check {
 		g.gen_is_none_check(node)
 	} else if (left.typ.is_ptr() && right.typ.is_int())
@@ -367,6 +369,18 @@ fn (mut g Gen) infix_expr_eq_op(node ast.InfixExpr) {
 			signed_type:   left.unaliased
 			signed_expr:   node.left
 		)
+	} else if left_is_option && right_is_option {
+		old_inside_opt_or_res := g.inside_opt_or_res
+		g.inside_opt_or_res = true
+		if node.op == .eq {
+			g.write('!')
+		}
+		g.write('memcmp(')
+		g.expr(node.left)
+		g.write('.data, ')
+		g.expr(node.right)
+		g.write('.data, sizeof(${g.base_type(left_type)}))')
+		g.inside_opt_or_res = old_inside_opt_or_res
 	} else {
 		g.gen_plain_infix_expr(node)
 	}

vlib/v/tests/options/option_indexexpr_eq_test.v

@@ -0,0 +1,7 @@
+fn test_main() {
+	x := []?int{len: 5, init: 1}
+	assert x[0] == x[1]
+
+	y := []?int{len: 4, init: 2}
+	assert !(x[0] == y[1])
+}