1615741 - Interaction of lack of AllowShared and unions seems to not follow the spec

Status: RESOLVED FIXED

(Core :: DOM: Bindings (WebIDL), defect, P1)

Description

[Boris Zbarsky [:bzbarsky]]

Consider this testcase:

    var xhr = new XMLHttpRequest();
    xhr.open("GET", "");
    xhr.send(new Uint8Array(new SharedArrayBuffer(2)));

I was expecting this to throw, but it does not. This is because our union code treats lack of [AllowShared] as meaning "a thing backed by a shared thing is not a valid value for the type, move to the next type", and we end up at the USVString branch of the union and stringify the object. I think per spec this should throw, though it talks about [AllowShared] creating a different type, etc... but the actual specced behavior is "same type, but with an extra check".

I expect the same thing would be a problem for array buffer views that are distinguishing arguments for overloads.

If my understanding of the spec is correct, then the fix is for onFailureIsShared to just ignore failureCode and always throw.

Comment 1

[Edgar Chen [:edgar]]

Yes, it should throw per current spec of converting a buffer source type.

Comment 2

[Edgar Chen [:edgar]]

Attachment: Bug 1615741 - Make converting a buffer source follow the spec when a shared buffer is passed in;

Converting a shared buffer source to buffer souce type should
always throw if the type isn't annotated with [AllowShared].

Comment 3

[Anne (:annevk)]

Thanks Edgar!

Comment 4

[Pulsebot]

Pushed by [e-mail]:
https://hg.mozilla.org/integration/autoland/rev/cb8677cbf5c6
Make converting a buffer source follow the spec when a shared buffer is passed in; r=bzbarsky

Comment 5

[Web Platform Test Sync Bot (Matrix: #interop:mozilla.org)]

Created web-platform-tests PR https://github.com/web-platform-tests/wpt/pull/21864 for changes under testing/web-platform/tests

Comment 6

[Web Platform Test Sync Bot (Matrix: #interop:mozilla.org)]

Upstream web-platform-tests status checks passed, PR will merge once commit reaches central.

Comment 7

[Oana Pop-Rus]

https://hg.mozilla.org/mozilla-central/rev/cb8677cbf5c6

Comment 8

[Web Platform Test Sync Bot (Matrix: #interop:mozilla.org)]

Upstream PR merged by moz-wptsync-bot