comparing a fake Map, Set, etc throws

[ljharb]

It seems like comparing anything that's a builtin that should have internal slots, that is only pretending to be that builtin, throws instead of returning false.

var maplikeSet = new Set();
Object.defineProperty(maplikeSet, 'constructor', { enumerable: false, value: Map });

deepEqual(maplikeSet, new Map());

this should return false, but instead, it throws:

TypeError: Method get Map.prototype.size called on incompatible receiver #<Map>

This bug is affecting v4 as well, so once fixed in v5, a backport would be appreciated.

I'd be happy to make a PR for both, if desired.

[keithamus]

Thanks for discovering and filing this issue. A PR would be great to see, thanks!

[ljharb]

→ #100

[ljharb]

Thanks! I’d love to make a PR to v4, but i think there’d need to be a v4 branch created first. Are you willing to make a branch and publish a backport if I make the PR?

[keithamus]

Sure. v4 branch has been created and is ready for a PR

[ljharb]

Thanks! → #101