Ensure sizeof returns correctly for isbits Union arrays. Fixes #23321

[quinnj]

The only other question I have is whether we should also define sizeof(Union{Void, Int8}), i.e. should sizeof return for isbits Unions? I feel like we should, mainly because it does actually have a definitize size now in structs & array elements.

[JeffBezanson]

should sizeof return for isbits Unions

👍 Yes I agree it should.

[JeffBezanson]

This logic should already be captured by ((jl_array_t*)x)->elsize. In fact, I believe it is.

[JeffBezanson]

Ah, except for the + len part. I'm not totally sure that should be reported as part of the array size; kind of a tough call.

[quinnj]

You're right, we can just use ->elsize. I updated the PR to not include the + len as part of the size. I think it will keep this more on the "optimization" side of things as opposed to necessarily committing to the layout. I also updated to give a size for isbits Union types.

[JeffBezanson]

We should have a more convenient jl_type_size function for just getting the size.

[quinnj]

In this case, we need the size and whether it's boxed anyway.

[quinnj]

I'm guessing this is an unrelated libuv travis failure

	From worker 6:	Assertion failed: (args[0]), function jl_uv_call_close_callback, file /Users/travis/build/JuliaLang/julia/src/jl_uv.c, line 73.
	From worker 6:	
	From worker 6:	signal (6): Abort trap: 6
	From worker 6:	while loading no file, in expression starting on line 0
	From worker 6:	__pthread_kill at /usr/lib/system/libsystem_kernel.dylib (unknown line)
	From worker 6:	Allocations: 224681289 (Pool: 224650756; Big: 30533); GC: 594

[fredrikekre]

Looks like #23215

[quinnj]

Do you want to take one more look @JeffBezanson?