(proxied function).prototype = ... about harmony-reflect HOT 2 CLOSED

Thanks for reporting. I know what causes the error, but am not yet sure how to fix it. I will send e-mail to es-discuss to discuss the best fix to the problem.

In a nutshell, what happens is the following:

fp.prototype = {} // this triggers the proxy's "set" trap
// since the "set" trap is not defined, the proxy defaults to calling:
Reflect.set(f, 'prototype', {}, fp) // note: the proxy fp itself is being passed as the "receiver" argument to Reflect.set

Inside Reflect.set, a test is made to check whether f === fp.
If this test is true, Reflect.set tries to update the existing 'prototype' property to the "receiver"
If this test is false, Reflect.set tries to add a new data property to the "receiver"

Since f === fp will fail, Reflect.set tries to add the data property {value: {}, enumerable:true, writable: true, configurable:true } to fp. The proxy in turn forwards this operation and tries to add the property to f, which fails because f already defines a property with the same name which is non-configurable, and one cannot change a non-configurable property into a configurable property.

There are a couple of fixes:

1. let the default "set" trap forward the operation as
   Reflect.set(f, 'prototype', {}, f) rather than Reflect.set(f, 'prototype', {}, fp)

2. change the f === fp test in Reflect.set to take proxies into account explicitly, and change it to:
   (f === fp || fp is a proxy for f)

from harmony-reflect.

The issue has been fixed. See commit notes referenced above.

from harmony-reflect.