cgen: fix array contains method with interface(fix #19670) (#19675)

vlib/v/gen/c/array.v

@@ -979,15 +979,18 @@ fn (mut g Gen) gen_array_contains(left_type ast.Type, left ast.Expr, right_type
 		g.write('->val')
 	}
 	g.write(', ')
-	if right.is_auto_deref_var() {
-		g.write('*')
-	}
 	left_sym := g.table.final_sym(left_type)
 	elem_typ := if left_sym.kind == .array {
 		left_sym.array_info().elem_type
 	} else {
 		left_sym.array_fixed_info().elem_type
 	}
+	if right.is_auto_deref_var()
+		|| (g.table.sym(elem_typ).kind !in [.interface_, .sum_type, .struct_] && right is ast.Ident
+		&& right.info is ast.IdentVar
+		&& g.table.sym(right.obj.typ).kind in [.interface_, .sum_type]) {
+		g.write('*')
+	}
 	if g.table.sym(elem_typ).kind in [.interface_, .sum_type] {
 		g.expr_with_cast(right, right_type, elem_typ)
 	} else {

vlib/v/gen/c/infix.v

@@ -622,6 +622,10 @@ fn (mut g Gen) infix_expr_in_optimization(left ast.Expr, right ast.ArrayInit) {
 			.string, .alias, .sum_type, .map, .interface_, .array, .struct_ {
 				if elem_sym.kind == .string {
 					g.write('string__eq(')
+					if left.is_auto_deref_var() || (left is ast.Ident && left.info is ast.IdentVar
+						&& g.table.sym(left.obj.typ).kind in [.interface_, .sum_type]) {
+						g.write('*')
+					}
 				} else {
 					ptr_typ := g.equality_fn(right.elem_type)
 					if elem_sym.kind == .alias {

vlib/v/tests/array_methods_test.v

@@ -39,3 +39,37 @@ fn test_any_called_with_opt_bool_fn() ? {
 	_ := [1, 2, 3].any(opt_bool_fn()?)
 	assert true
 }
+
+interface Args {}
+
+const some_strings = ['one', 'two', 'three']
+
+// For test `gen array contains method`
+fn test_array_contains_method_with_interface() {
+	arg := Args('one')
+	match arg {
+		string {
+			if arg in some_strings {
+				assert true
+				return
+			}
+		}
+		else {}
+	}
+	assert false
+}
+
+// For test `gen string_eq method`
+fn test_string_eq_method_with_interface() {
+	arg := Args('three')
+	match arg {
+		string {
+			if arg in ['one', 'two', 'three'] {
+				assert true
+				return
+			}
+		}
+		else {}
+	}
+	assert false
+}