1158222 - Implement last-minute change to ES6 [[Set]]

Status: RESOLVED FIXED

(Core :: JavaScript Engine, defect)

Description

[Jason Orendorff [:jorendorff]]

https://bugs.ecmascript.org/show_bug.cgi?id=4331

Comment 1

[Tom S [:evilpie]]

Attachment: Implement the new [[Set]] receiver restrictions

Comment 2

[Jason Orendorff [:jorendorff]]

Comment on attachment 8606971 [details] [diff] [review]
Implement the new [[Set]] receiver restrictions

Review of attachment 8606971 [details] [diff] [review]:
-----------------------------------------------------------------

Great. r=me.

::: js/src/proxy/BaseProxyHandler.cpp
@@ +175,2 @@
>          unsigned attrs =
> +            !!existingDescriptor.object()

Is the !! necessary here?

::: js/src/tests/ecma_6/Proxy/proxy-no-receiver-overwrite.js
@@ +15,5 @@
> +        throw "not invoked";
> +    }
> +})
> +
> +// This will invoke [[Set]] on the target, with the proxy as receiver.

Great test!

::: js/src/vm/NativeObject.cpp
@@ +1980,4 @@
>          // The common case. The caller has necessarily done a property lookup
>          // on obj and passed us the answer as objHasOwn.
> +        // We also know that the property is a data property and writable
> +        // iff it exists.

Plain "if" is more plain-spoken and logically just as good as "iff" here.

Comment 3

[Pulsebot]

https://hg.mozilla.org/integration/mozilla-inbound/rev/8a807d40c36f

Comment 4

[Phil Ringnalda (:philor)]

https://hg.mozilla.org/mozilla-central/rev/8a807d40c36f

Comment 5

[Florian Scholz (Open Web Docs)]

Added an example to https://developer.mozilla.org/en-US/docs/Web/JavaScript/Reference/Operators/super#Super.prop_can_not_overwrite_non-writable_properties