checker: check fn_variadic with array_decompose (#8894)

vlib/v/checker/checker.v

@@ -1921,6 +1921,11 @@ pub fn (mut c Checker) call_fn(mut call_expr ast.CallExpr) table.Type {
 		} else {
 			f.params[i]
 		}
+		if f.is_variadic && call_arg.expr is ast.ArrayDecompose {
+			if i > f.params.len - 1 {
+				c.error('too many arguments in call to `$f.name`', call_expr.pos)
+			}
+		}
 		c.expected_type = arg.typ
 		typ := c.expr(call_arg.expr)
 		call_expr.args[i].typ = typ

vlib/v/checker/tests/function_variadic_arg_array_decompose.out

@@ -0,0 +1,6 @@
+vlib/v/checker/tests/function_variadic_arg_array_decompose.vv:11:10: error: too many arguments in call to `sum`
+    9 | fn main() {
+   10 |     b := [5, 6, 7]
+   11 |     println(sum(1, 2, ...b))
+      |             ~~~~~~~~~~~~~~~
+   12 | }

vlib/v/checker/tests/function_variadic_arg_array_decompose.vv

@@ -0,0 +1,12 @@
+fn sum(a ...int) int {
+	mut total := 0
+	for x in a {
+		total += x
+	}
+	return total
+}
+
+fn main() {
+	b := [5, 6, 7]
+	println(sum(1, 2, ...b))
+}