Incorrect inspection of Set iterator for set.entries()

Version: 10, 11, master
Platform: Linux
Subsystem: util

var set = new Set([1, 2])
console.log(set.entries())

In Node 6 and 8, it outputs:

SetIterator { [ 1, 1 ], [ 2, 2 ] }

In Node 10, 11 and master:

[Set Iterator] { 1, 2 }

Object::PreviewEntries reports unkeyed and gives the flat array.

@nodejs/v8

Yeah, Chrome has the same behavior:

@BridgeAR

/ping @BridgeAR

AFAIC this works as intended. With the change to using Object::PreviewEntries this difference has been discussed as well and we decided to follow chrome.
The set entries only contain the values, so there is no need to display it as an array with the value duplicated.

@BridgeAR

@BridgeAR its not an accurate representation of the actual iterator results though...

> new Set([2, 4]).entries()
[Set Iterator] { 2, 4 }
> // oh ok its just some numbers
> new Set([2, 4]).entries().next()
{ value: [ 2, 2 ], done: false }
> // wait value is an array now?
>

It's true that they contain the values but they are still in arrays, so IMHO it is confusing to not see that in the preview.

I just fixed Object::PreviewEntries to work as intended locally and I'll raise a PR to V8 as soon as I set up the whole machinery for V8 PRs and I'll backport that as soon as it lands.

ruben@BridgeAR-T450s:~/repos/node/node$ ./node
> a = new Set([1,2,3])
Set { 1, 2, 3 }
> a.values()
[Set Iterator] { 1, 2, 3 }
> a.keys()
[Set Iterator] { 1, 2, 3 }
> a.entries()
[Set Iterator] { [ 1, 1 ], [ 2, 2 ], [ 3, 3 ] }
> process.versions
{ http_parser: '2.8.0',
  node: '12.0.0-pre',
  v8: '7.0.276.38-node.13',

Refs: #20831 (the original PR that changed the behavior)

@BridgeAR

@BridgeAR what's the status?

@targos

@targos I have to fix the Node.js test expectation first in another PR for V8 as those tests will now fail (Which is intended). I am working on that.

The actual CL to fix the preview: https://chromium-review.googlesource.com/c/v8/v8/+/1350790

Fix preview of set entries

util: update set iterator entries inspection

deps: V8: backport 74571c8

util: update set iterator entries inspection

deps: V8: backport 74571c8

util: update set iterator entries inspection

deps: V8: cherry-pick 74571c8

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Incorrect inspection of Set iterator for set.entries() #24629

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Incorrect inspection of Set iterator for set.entries() #24629

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devsnek commented on Nov 24, 2018

targos commented on Nov 24, 2018

Trott commented on Nov 24, 2018

BridgeAR commented on Nov 24, 2018

devsnek commented on Nov 24, 2018

targos commented on Nov 24, 2018

BridgeAR commented on Nov 25, 2018

targos commented on Dec 16, 2018

BridgeAR commented on Dec 18, 2018

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