cgen: fix multi return with option type

vlib/v/gen/c/cgen.v

@@ -5517,10 +5517,9 @@ fn (mut g Gen) concat_expr(node ast.ConcatExpr) {
 		g.write('(${styp}){')
 		for i, expr in node.vals {
 			g.write('.arg${i}=')
-			if types[i].has_flag(.option) && expr.is_literal() {
-				g.write('{.data=')
-				g.expr(expr)
-				g.write('}')
+			expr_typ := g.get_expr_type(expr)
+			if expr_typ != ast.void_type && types[i].has_flag(.option) {
+				g.expr_with_opt(expr, expr_typ, types[i])
 			} else {
 				old_left_is_opt := g.left_is_opt
 				g.left_is_opt = true
@@ -5942,7 +5941,7 @@ fn (mut g Gen) return_stmt(node ast.Return) {
 					multi_unpack += g.go_before_last_stmt()
 					g.write(line)
 					expr_styp := g.base_type(call_expr.return_type)
-					tmp = ('(*(${expr_styp}*)${tmp}.data)')
+					tmp = '(*(${expr_styp}*)${tmp}.data)'
 				}
 				expr_types := expr_sym.mr_info().types
 				for j, _ in expr_types {

vlib/v/gen/c/comptime.v

@@ -472,6 +472,21 @@ fn (mut g Gen) get_expr_type(cond ast.Expr) ast.Type {
 				}
 			}
 		}
+		ast.IntegerLiteral {
+			return ast.int_type
+		}
+		ast.BoolLiteral {
+			return ast.bool_type
+		}
+		ast.StringLiteral {
+			return ast.string_type
+		}
+		ast.CharLiteral {
+			return ast.char_type
+		}
+		ast.FloatLiteral {
+			return ast.f64_type
+		}
 		else {
 			return ast.void_type
 		}

vlib/v/tests/options/option_multi_return_opt_test.v

@@ -0,0 +1,10 @@
+fn fails(i int) !(int, ?int) {
+	return error('fails')
+}
+
+fn test_main() {
+	a2, b2 := fails(2) or { 22, 22 }
+	c2 := b2? as int
+	assert b2 != none
+	assert a2 == c2
+}