From 4d7e3578f7c3b4fe095fcf98dd2b5351f4147d7b Mon Sep 17 00:00:00 2001
From: Krchi <997054144@qq.com>
Date: Sun, 14 Dec 2025 19:17:26 +0800
Subject: [PATCH] checker,cgen: fix variadic call on sumtype with array of
 itself (fix #25898) (#25964)

---
 vlib/v/checker/fn.v                           |  3 +-
 .../tests/sumtype_array_to_variadic.vv        |  2 +-
 vlib/v/gen/c/fn.v                             |  3 +-
 ...iadic_sumtype_with_it_array_variant_test.v | 29 +++++++++++++++++++
 4 files changed, 34 insertions(+), 3 deletions(-)
 create mode 100644 vlib/v/tests/fns/call_args_variadic_sumtype_with_it_array_variant_test.v

diff --git a/vlib/v/checker/fn.v b/vlib/v/checker/fn.v
index ef418d942..cc7c04ade 100644
--- a/vlib/v/checker/fn.v
+++ b/vlib/v/checker/fn.v
@@ -4068,7 +4068,8 @@ fn (mut c Checker) check_variadic_arg(arg_expr ast.Expr, typ ast.Type, expected_
 	styp := c.table.type_to_str(typ)
 	elem_styp := c.table.type_to_str(expected_type)
 	expected_kind := c.table.sym(expected_type).kind
-	sum_type_needs_spread := expected_kind == .sum_type && is_single_array_arg
+	sum_type_needs_spread := expected_kind == .sum_type
+		&& !c.table.sumtype_has_variant(expected_type, typ, false) && is_single_array_arg
 	if kind == .array && !is_decompose && !allow_variadic_pass
 		&& (expected_kind !in [.sum_type, .interface] || sum_type_needs_spread)
 		&& !param_typ.has_flag(.generic) && expected_type != typ {
diff --git a/vlib/v/checker/tests/sumtype_array_to_variadic.vv b/vlib/v/checker/tests/sumtype_array_to_variadic.vv
index 711374ae7..1ba594821 100644
--- a/vlib/v/checker/tests/sumtype_array_to_variadic.vv
+++ b/vlib/v/checker/tests/sumtype_array_to_variadic.vv
@@ -2,7 +2,7 @@ type Nil = u8
 
 const c_nil = Nil(`\0`)
 
-pub type Value = Nil | int | string | []Value | Map
+pub type Value = Nil | int | string | Map
 
 pub fn (v Value) string() string {
 	return '${v.str()}'
diff --git a/vlib/v/gen/c/fn.v b/vlib/v/gen/c/fn.v
index 2da8a8de7..52bfe22cd 100644
--- a/vlib/v/gen/c/fn.v
+++ b/vlib/v/gen/c/fn.v
@@ -2647,7 +2647,8 @@ fn (mut g Gen) call_args(node ast.CallExpr) {
 					if variadic_count == 1
 						&& ((args[arg_nr].typ.has_flag(.variadic) && args[arg_nr].typ == varg_type)
 						|| (varg_type.has_flag(.variadic)
-						&& args[arg_nr].typ == varg_type.clear_flag(.variadic))) {
+						&& args[arg_nr].typ == varg_type.clear_flag(.variadic)
+						&& !g.table.sumtype_has_variant(arr_info.elem_type, args[arg_nr].typ, false))) {
 						g.ref_or_deref_arg(args[arg_nr], arr_info.elem_type, node.language,
 							false)
 					} else {
diff --git a/vlib/v/tests/fns/call_args_variadic_sumtype_with_it_array_variant_test.v b/vlib/v/tests/fns/call_args_variadic_sumtype_with_it_array_variant_test.v
new file mode 100644
index 000000000..79541e26c
--- /dev/null
+++ b/vlib/v/tests/fns/call_args_variadic_sumtype_with_it_array_variant_test.v
@@ -0,0 +1,29 @@
+type Any = []Any | int
+
+fn print_any(arr ...Any) {
+	if any := arr[0] {
+		match any {
+			int {
+				assert any == 1
+			}
+			[]Any {
+				assert any == [Any(1)]
+			}
+		}
+	}
+	println(arr)
+}
+
+fn print_int_any(_ int, arr ...Any) {
+	print_any(...arr)
+}
+
+fn test_main() {
+	print_any(1, Any(1), [Any(1)])
+	print_any(1)
+	print_any(Any(1))
+	print_any([Any(1)])
+	print_any([Any(1)], 1)
+	print_int_any(1, 1)
+	print_int_any(1, [Any(1)])
+}
-- 
2.39.5