checker: add check for decomposing to interface (fix #24441) (#24453)

vlib/v/checker/fn.v

@@ -1612,6 +1612,12 @@ fn (mut c Checker) fn_call(mut node ast.CallExpr, mut continue_check &bool) ast.
 				c.error('cannot use `${got_typ_str}` as `${expected_typ_str}` in argument ${i + 1} to `${fn_name}`',
 					call_arg.pos)
 			}
+			if call_arg.expr is ast.ArrayDecompose && arg_typ.idx() != final_param_typ.idx() {
+				expected_type_str := c.table.type_to_str(param.typ)
+				got_type_str := c.table.type_to_str(arg_typ)
+				c.error('cannot use `${got_type_str}` as `${expected_type_str}` in argument ${i + 1} to `${fn_name}`',
+					call_arg.pos)
+			}
 			continue
 		}
 		if param.typ.is_ptr() && !param.is_mut && !call_arg.typ.is_any_kind_of_pointer()

vlib/v/checker/tests/decompose_interface_err.out

@@ -0,0 +1,20 @@
+vlib/v/checker/tests/decompose_interface_err.vv:3:8: warning: module 'arrays' is imported but never used
+    1 | module main
+    2 | 
+    3 | import arrays
+      |        ~~~~~~
+    4 | 
+    5 | interface Value {}
+vlib/v/checker/tests/decompose_interface_err.vv:17:2: warning: unused variable: `region_id`
+   15 |         'AF',
+   16 |     ]
+   17 |     region_id := 'something'
+      |     ~~~~~~~~~
+   18 |     some_function(...country_ids)
+   19 | }
+vlib/v/checker/tests/decompose_interface_err.vv:18:16: error: cannot use `string` as `Value` in argument 1 to `some_function`
+   16 |     ]
+   17 |     region_id := 'something'
+   18 |     some_function(...country_ids)
+      |                   ~~~~~~~~~~~~~~
+   19 | }

vlib/v/checker/tests/decompose_interface_err.vv

@@ -0,0 +1,19 @@
+module main
+
+import arrays
+
+interface Value {}
+
+fn some_function(values ...Value) {
+	println(values)
+}
+
+fn main() {
+	country_ids := [
+		'AD',
+		'AE',
+		'AF',
+	]
+	region_id := 'something'
+	some_function(...country_ids)
+}