Open
Description
Bug Description
See explainer, test and a monkey-patch fix at https://github.com/ExodusMovement/patch-broken-hermes-typed-arrays
> Buffer.alloc(10).subarray(0).toString('hex')
'0,0,0,0,0,0,0,0,0,0'
// What?Sections of specification broken in Hermes:
- ECMAScript® Language Specification,
%TypedArray%.prototype.subarray - ECMAScript® Language Specification,
%TypedArray%.prototype.map - ECMAScript® Language Specification,
%TypedArray%.prototype.filter - ECMAScript® Language Specification,
%TypedArray%.prototype.slice
See https://github.com/ExodusMovement/patch-broken-hermes-typed-arrays/blob/main/index.js for links to specific spec steps
See ecosystem fallout in feross/buffer#329
- I
have runconfirmed this bug does not occur with JSCgradle cleanand - The issue is reproducible with the latest version of
React Native.Hermes
Hermes git revision (if applicable): 0410fb4 (latest main)
React Native version: 🤷🏻
OS:
Platform (most likely one of arm64-v8a, armeabi-v7a, x86, x86_64):
Steps To Reproduce
See full explainer, test and a monkey-patch fix at https://github.com/ExodusMovement/patch-broken-hermes-typed-arrays
chalker@Nikitas-Air hermes_workingdir % cat bad-inheritance.js
var TestArray = function (...args) {
print('called TestArray constructor')
var buf = new Uint8Array(...args)
Object.setPrototypeOf(buf, TestArray.prototype)
return buf
}
Object.setPrototypeOf(TestArray.prototype, Uint8Array.prototype)
Object.setPrototypeOf(TestArray, Uint8Array)
var arr = new TestArray(10)
var mapped = arr.map((_, i) => i * 10)
print(mapped.constructor.name)
chalker@Nikitas-Air hermes_workingdir % jsc bad-inheritance.js
called TestArray constructor
called TestArray constructor
TestArray
chalker@Nikitas-Air hermes_workingdir % ./build_release/bin/hermes bad-inheritance.js
called TestArray constructor
Uint8ArrayThe Expected Behavior
Implementation of TypedArray per spec, perhaps without Symbol.species but with working inheritance
See spec refs above