Internal error: tried to substitute for mutated var
Someone on #ligo provided this example:
$ ligo run test bug.ligo
An internal error ocurred. Please, contact the developers.
internal error, please report this as a bug: tried to substitute for mutated var File "src/passes/15-self_mini_c/subst.ml", line 312, characters 105-112.
type internal_storage is [@layout:comb] record [
value : int;
]
type storage is [@layout:comb] record [
internal_storage : internal_storage;
]
type parameter is
Reset
type return is list (operation) * storage
function reset (var s : storage) : storage is {
s.internal_storage.value := 0;
} with (s);
function main (const action : parameter; const s : storage) : return is
((nil : list (operation)), // No operations
case action of [
| Reset -> reset(s)
]);
const test_reproducing = {
const initial_storage: storage = record [
internal_storage = record [
value = 0;
];
];
const (_typed_address, _, _) = Test.originate(main, initial_storage, 0tez);
} with ("OK")
It appears the problem is that somehow the mutable function parameter (for reset
) winds up being compiled to a normal function parameter which is incorrectly mutated:
(let reset =
fun s#3371 ->
(let ()#3372 =
s#3371 := { !s#3371 with (0) = { (!s#3371).(0) with (0) =
L(0) } } in
!s#3371) in