'Type layout' and 'Dynamically Sized Types' pages disagree on whether the size of a pointer to a DST is defined

[Liamolucko]

The 'Dynamically Sized Types' page pretty clearly states that the size of a pointer to a DST is twice the size of a regular pointer:

• Pointer types to DSTs are sized but have twice the size of pointers to sized types

But, the 'Type layout' page gives this much less concrete answer:

• Pointers to unsized types are sized. The size and alignment is guaranteed to be at least equal to the size and alignment of a pointer.

And, in a note, it says the same thing as the DST page, but says that it shouldn't be relied upon:

Note: Though you should not rely on this, all pointers to DSTs are currently twice the size of the size of usize and have the same alignment.

The two pages should be consistent. Assuming that the DST page is correct, the type layout page should also concretely say that pointers to unsized types are twice the size of regular pointers, and the note should be removed.

[bjorn3]

You can have pointers to DST's that are the same size as pointers to regular types using the unstable extern { type Foo; }. In the future we might also get them larger than twice the size of regular pointers if we get custom DST's.

[Liamolucko]

Okay - so the DST page is wrong?

[bjorn3]

It is outdated. extern { type Foo; } probably didn't exist yet when that page was written.