Deep equality for sets fails in Node v20

[WeepingClown13]

I tried this:

let a = MutSet<Map<str>> {{"a" => "b", "c" => "d"}};
let b = a.copy();
assert(a == b);

let c = b.copyMut();
assert(a == c);

a.add({"e" => "f"});
c.add({"e" => "f"});
assert(a == {{"a" => "b", "c" => "d"}, {"e" => "f"}});
assert(c == {{"a" => "b", "c" => "d"}, {"e" => "f"}});
assert(a == c);

This happened:

Assertion failed with the following error (it is the final assert that is causing this):

ERROR: assertion failed: a == c

target/test/main.wsim.354620.tmp/.wing/preflight.js:17
       {((cond) => {if (!cond) throw new Error("assertion failed: a == {{\"a\" => \"b\", \"c\" => \"d\"}, {\"e\" => \"f\"}}")})((((a,b) => { try { return require('assert').deepStrictEqual(a,b) === undefined; } catch { return false; } })(a,new Set([({"a": "b","c": "d"}), ({"e": "f"})]))))};
       {((cond) => {if (!cond) throw new Error("assertion failed: c == {{\"a\" => \"b\", \"c\" => \"d\"}, {\"e\" => \"f\"}}")})((((a,b) => { try { return require('assert').deepStrictEqual(a,b) === undefined; } catch { return false; } })(c,new Set([({"a": "b","c": "d"}), ({"e": "f"})]))))};
>>     {((cond) => {if (!cond) throw new Error("assertion failed: a == c")})((((a,b) => { try { return require('assert').deepStrictEqual(a,b) === undefined; } catch { return false; } })(a,c)))};
     }
   }

I expected this:

For the assertions to pass without any errors.

Is there a workaround?

Run the tests by removing the final assertion, like so:

let a = MutSet<Map<str>> {{"a" => "b", "c" => "d"}};
let b = a.copy();
assert(a == b);

let c = b.copyMut();
assert(a == c);

a.add({"e" => "f"});
c.add({"e" => "f"});
assert(a == {{"a" => "b", "c" => "d"}, {"e" => "f"}});
assert(c == {{"a" => "b", "c" => "d"}, {"e" => "f"}});
// assert(a == c);

Which passes as expected: Tasks: 12 successful, 12 total

Component

Compiler

Wing Version

0.35.5

Node.js Version

v20.8.0

Platform(s)

Linux

Anything else?

Originally noticed this issue because of a CI failure for the PR #4432. This behavior only happens with node v20 as seen in the pipeline and upon further testing in local environment, it is confirmed that it still passes (the snippet I provided here, as well as the one that caused the ci failure) in node v18, but fails in node v20.

Community Notes

• Please vote by adding a 👍 reaction to the issue to help us prioritize.
• If you are interested to work on this issue, please leave a comment.

[Chriscbr]

it is confirmed that it still passes (the snippet I provided here, as well as the one that caused the ci failure) in node v18, but fails in node v20.

@WeepingClown13 To clarify the issue title, is it always failing on Node v20, or is it only sometimes failing (i.e. the behavior is nondeterministic)?

[WeepingClown13]

Is it always failing on Node v20, or is it only sometimes failing (i.e. the behavior is nondeterministic)?

It is always failing on Node v20, so it's consistent. The same always passes in Node v18.

[staycoolcall911]

I can confirm this fails on node 20, but succeeds on node 18, very strange...

[github-actions]

Hi,

This issue hasn't seen activity in 60 days. Therefore, we are marking this issue as stale for now. It will be closed after 7 days.
Feel free to re-open this issue when there's an update or relevant information to be added.
Thanks!

[Chriscbr]

I thought this could be related to running preflight code in a worker thread, but it turns out it's unrelated. This bug is basically due to how we're using deepStrictEqual here, which treats sets as equal only if they contain the same JavaScript values by reference. (nodejs/node#13347)

[monadabot]

Congrats! 🚀 This was released in Wing 0.74.32.