Async function execute in different version got different output about async function itself

[Jiasm]

• Node.js Version: 11.7.0 & 10.15.0
• OS: macOS
• Scope (install, code, runtime, meta, other?): runtime

I found an interesting things,
Simple test code:

async function test () {
  await 1
}

console.log(test.constructor.name, test.prototype)

test()

console.log(test.constructor.name, test.prototype)

When I use the 10.15.0 version, I got two different outputs.
This does not appear on the 11.7.0 version.

I did not find the relevant modification record on the ChangeLog.
I'm not sure if it is a bug fix, or an implementation change. Can you provide the corresponding information?
I'm more interested in this, thank you.

[vsemozhetbyt]

On Windows 7 x64:

>node.08.15.0.v8-6.2.exe test.js
AsyncFunction undefined
AsyncFunction {}

>node.10.15.0.v8-6.8.exe test.js
AsyncFunction undefined
AsyncFunction Object [Generator] {}

>node.11.7.0.v8-7.0.exe test.js
AsyncFunction undefined
AsyncFunction undefined

[vsemozhetbyt]

cc @nodejs/v8

[Hakerh400]

Seems like it was a bug in old V8.

async function test(){await 1}
test()
console.log('prototype' in test)    // false
console.log(test.prototype)         // Object [Generator] {}
console.log(test['prototype'])      // Object [Generator] {}
console.log(test['prototype' + '']) // undefined

There's no semantical difference between the last two lines, but they give different results.

[yathamravali]

I did bisect and landed with this PR:
nodejs/node#22390
I'm not sure whether this is a bug or Enhancement. Copying the author to get more insight.
cc @TimothyGu

[TimothyGu]

@yathamravali The referenced PR was later reverted: nodejs/node#22911. So it couldn’t have been that.

[TimothyGu]

@Hakerh400’s analysis seems correct though.

[gireeshpunathil]

closing as answered, let me know if there is anything outstanding here

[Hakerh400]

I did more research on this. This bisects to nodejs/node@0e7ddbd (brought by PR nodejs/node#22754). Further bisecting V8 revealed that the bug is fixed in v8/v8@4ef4dea, as a special case of v8/v8#5085. The relevant test, which is basically the same script from the OP, that was added in that commit is test-regress-5085.