json: fix decode codegen for []&type (fix #23007) (#23010)

Author: felipensp

vlib/json/tests/json_decode_arr_ref_test.v

@@ -0,0 +1,10 @@
+import json
+
+struct Test {
+	a string
+}
+
+fn test_main() {
+	x := json.decode([]&Test, '[{"a":"a"}]') or { exit(1) }
+	assert x[0].a == 'a'
+}

vlib/v/gen/c/json.v

@@ -1021,7 +1021,7 @@ fn (mut g Gen) decode_array(utyp ast.Type, value_type ast.Type, fixed_array_size
 		s = '${styp} val = ${fn_name}((cJSON *)jsval); '
 	} else if is_array_fixed_val {
 		s = '
-		${result_name}_${styp} val2 = ${fn_name} ((cJSON *)jsval);
+		${result_name}_${styp.replace('*', '_ptr')} val2 = ${fn_name} ((cJSON *)jsval);
 		if(val2.is_error) {
 			${array_free_str}
 			return *(${result_name}_${ret_styp}*)&val2;
@@ -1030,7 +1030,7 @@ fn (mut g Gen) decode_array(utyp ast.Type, value_type ast.Type, fixed_array_size
 		memcpy(&val, (${styp}*)val2.data, sizeof(${styp}));'
 	} else {
 		s = '
-		${result_name}_${styp} val2 = ${fn_name} ((cJSON *)jsval);
+		${result_name}_${styp.replace('*', '_ptr')} val2 = ${fn_name} ((cJSON *)jsval);
 		if(val2.is_error) {
 			${array_free_str}
 			return *(${result_name}_${ret_styp}*)&val2;