The fetch spec's Request's body can be a blob [1]. Our codegen generates unwrapping code for main thread, but Blob has special handling on the worker to get a Blob from JS::Value, leading to crashes when a Blob is passed as the body. [1]: https://fetch.spec.whatwg.org/#bodyinit

See bug 809899. Sadly, it seems we'll compile stuff now, just incorrect stuff. I wonder whether we can do better here... For the case of Blob, the right answer is to land bug 1047483, right?

Maybe what we can do is have union ctors assert mainthread if the union contains any interface type which has different worker and non-worker descriptors? That would at least catch the issue early in debug builds...

Just noting that this affects the Response object as well.

I think this bug is fixed by bug 1047483. Can you try again?

Thanks! That works.

Comment on attachment 8502753 [details] [diff] [review] Allow Blobs in Fetch BodyInit Review of attachment 8502753 [details] [diff] [review]: ----------------------------------------------------------------- ::: dom/fetch/Fetch.cpp @@ +114,5 @@ > } > } > > nsresult > +ExtractByteStreamFromBody(const OwningArrayBufferOrArrayBufferViewOrBlobOrScalarValueStringOrURLSearchParams& aBodyInit, wow. This is a really cool type name. @@ +122,5 @@ > MOZ_ASSERT(aStream); > > if (aBodyInit.IsArrayBuffer()) { > const ArrayBuffer& buf = aBodyInit.GetAsArrayBuffer(); > return ExtractFromArrayBuffer(buf, aStream); So actually, just because you are returning value, I think we should have this: if (aBodyInit.IsArrayBuffer()) { ... return ... } if ( ... ) { return ... } @@ +157,5 @@ > const ArrayBufferView& buf = aBodyInit.GetAsArrayBufferView(); > return ExtractFromArrayBufferView(buf, aStream); > + } else if (aBodyInit.IsBlob()) { > + const File& blob = aBodyInit.GetAsBlob(); > + return ExtractFromBlob(blob, aStream, aContentType); save comment here.

I actually can't land this until the Response + Split InternalHeaders patch is reviewed :)

remote: https://hg.mozilla.org/integration/mozilla-inbound/rev/caa56adec4f5 Andrea, I forgot to make the else-if to if change you suggested :/ Will there be performance savings in converting? If so, i can push a followup

> I forgot to make the else-if to if change you suggested :/ Will there be > performance savings in converting? If so, i can push a followup This code is changing quickly. Let's do it next time we touch this code.