How can I get the size of a type?

[NSExceptional]

I'm trying to write a JSON decoder, and I'm starting with tuples. I'm enumerating the elements and labels of a tuple and using UnsafeMutableRawPointer.copyMemory(from:byteCount:), but I don't know where to get the byte count from.

[NSExceptional]

Crossposting answer from @Azoy:

If you can, you can use MemoryLayout<Type>.size, but if all you have is the metadata (or a generic Any.Type) you can get the type's size from metadata.vwt.size. Keep in mind though, that for tuples you could have something like: (Int8, Int, Int8) and currently the compiler emits padding for the first byte integer, so simply iterating the raw value by its element type size might not always work.

[NSExceptional]

Then I ask if TupleMetadata.Element.offset would work, and he said yes