cgen: fix fixed array option cast with none (fix #23164) (#23168)

vlib/v/gen/c/cgen.v

@@ -5364,10 +5364,14 @@ fn (mut g Gen) cast_expr(node ast.CastExpr) {
 		g.expr(node.expr)
 		g.write('))')
 	} else if sym.kind == .alias && g.table.final_sym(node.typ).kind == .array_fixed {
-		if node.expr is ast.ArrayInit && g.assign_op != .decl_assign {
-			g.write('(${g.styp(node.expr.typ)})')
+		if node.typ.has_flag(.option) {
+			g.expr_with_opt(node.expr, expr_type, node.typ)
+		} else {
+			if node.expr is ast.ArrayInit && g.assign_op != .decl_assign {
+				g.write('(${g.styp(node.expr.typ)})')
+			}
+			g.expr(node.expr)
 		}
-		g.expr(node.expr)
 	} else if expr_type == ast.bool_type && node.typ.is_int() {
 		styp := g.styp(node_typ)
 		g.write('(${styp}[]){(')

vlib/v/tests/alias_cast_to_fixed_array_test.v

@@ -0,0 +1,24 @@
+type Bytes = [3]u8
+type Strs = [3]string
+
+fn test_none() {
+	b := ?Bytes(none)
+	println(b)
+	assert b == none
+
+	c := ?Strs(none)
+	println(c)
+	assert c == none
+}
+
+fn test_non_none() {
+	b := ?Bytes([u8(1), 2, 3]!)
+	println(b)
+	assert b != none
+	assert b?[2] == 3
+
+	c := ?Strs(['a', 'b', 'c']!)
+	println(c)
+	assert c != none
+	assert c?[2] == 'c'
+}