[stdlib] Use UnsafePointer in vector.mojo

[gabrieldemarmiesse]

With this change I get a weird error:

 ./stdlib/scripts/run-tests.sh && lit -sv stdlib/test
Creating build directory for building the stdlib running the tests in.
Packaging up the Standard Library.
Included from /projects/open_source/mojo/stdlib/src/collections/__init__.mojo:1:
/projects/open_source/mojo/stdlib/src/collections/vector.mojo:250:48: error: '_VecIter' parameter #2 has 'fn(UnsafePointer[InlinedFixedVector[type, size], 0], Int, /) -> type' type, but value has type 'fn(selfptr: UnsafePointer[InlinedFixedVector[type, size], 0], i: Int, /) -> type'
    alias _iterator = _VecIter[type, Self, Self._deref_iter_impl]
                                           ~~~~^~~~~~~~~~~~~~~~~
/projects/open_source/mojo/stdlib/src/__init__.mojo:1:1: note: '_VecIter' declared here
# ===----------------------------------------------------------------------=== #
^
mojo: error: failed to parse the provided Mojo source module

That does seem like a compiler bug no? Those looks the same to me:

fn(UnsafePointer[InlinedFixedVector[type, size], 0], Int, /) -> type
fn(selfptr: UnsafePointer[InlinedFixedVector[type, size], 0], i: Int, /) -> type

Maybe I'm missing something?

[Moosems]

Not the same, one has a named argument ((sarcasm) yeah, I think it's a compiler bug).

[JoeLoser]

Thanks for pushing on this! I'll import the PR internally and we'll take a look at the compiler bug and see if there's a workaround, etc.

[lattner]

Thanks for poking me about this Joe. @gabrieldemarmiesse the problem here is a disagreement about AnyRegType, I think it works if you change VecIter to:

@value
struct _VecIter[
    type: AnyRegType,
    vec_type: AnyType,
    deref: fn (UnsafePointer[vec_type], Int) -> type,

AnyRegType is a bad thing :), we need to move off it completely to use AnyType.

[gabrieldemarmiesse]

Thanks @lattner it works well :) This PR is ready for review now

[soraros]

Maybe:

Suggested change

	0, self.current_size, UnsafePointer(Reference(self))
	0, self.current_size, UnsafePointer.address_of(self)

[JoeLoser]

Landed in #2559!