TypedArray(typedArray) must be modified for SharedArrayBuffer

[lars-t-hansen]

The problem is that if the current spec is taken as-is, we end up with some weird objects, eg, I've seen an ArrayBuffer with a prototype that is the SharedArrayBufferPrototype.

See https://bugzilla.mozilla.org/show_bug.cgi?id=1314564 for more information. Excerpted from there:

me:

The intent of the Shared Memory spec is that the TypedArray methods should
construct plain ArrayBuffers in this case. I'll take a look at the prose
you point to.

@anba:

Okay. In that case, the Shared Memory spec needs to specify the following changes to 22.2.4.3, steps 17-18:

17. If SameValue(elementType, srcType) is true, then
    a. Let srcLength be typedArray.[[ByteLength]].
    b. If IsSharedArrayBuffer(srcData) is false, then
        i. Let data be ? CloneArrayBuffer(srcData, srcByteOffset, srcLength).
    c. Else,
        i. Let data be ? CloneArrayBuffer(srcData, srcByteOffset, srcLength, %ArrayBuffer%).
18. Else,
    a. If IsSharedArrayBuffer(srcData) is false, then
        i. Let bufferConstructor be ? SpeciesConstructor(srcData, %ArrayBuffer%).
    b. Else,
        i. Let bufferConstructor be %ArrayBuffer%.
    b. Let data be ? AllocateArrayBuffer(bufferConstructor, byteLength).

This seems reasonable to me. Discuss.

[lars-t-hansen]

It also does not seem that there are other, analogous cases in the spec that need similar handling.