Finalize and update visitor interface

[nikomatsakis]

The type visitor interface includes various outdated bits of cruft related to how types used to be, particularly around functions. For example, there is a ret_style, and bare fns and closures are not well distinguished. This should be updated.

[graydon]

still very much valid, properly tagged, 2013-06-11. see also #2595, #3727, #2594, #3475. pure cleanup.

[bblum]

is the visitor not something internal to rustc? I only know of the AST visitor. (if so this shouldn't be backwards-compatible milestone)

[thestinger]

There's a TyVisitor implemented in librustc/middle/trans/reflect.rs, exposed in std::reflect and used in std::repr. The %? formatter used by fmt! is implemented with std::repr.

As far as I know, there are no other users.

[thestinger]

I've done a bit of work on this in order to improve repr, but it's still in serious need of an overhaul.

[thestinger]

I don't think we should ever make this a stable public interface, because it reveals too many internal compiler details. It would prevent us from adding new primitives in a backwards compatible way. Even a TyDesc should be an implementation detail, and it's exposed in this API.

[catamorphism]

Clearing milestone, as per @thestinger 's argument

[brson]

Agree that the visitor itself should not be a public interface. we should have a higher-level reflection api someday.

[flaper87]

Triage: It looks like there are still things to cleanup.

FWIW, I agree TyVisitor shouldn't be a public interface.

[thestinger]

This interface has been removed.

[nikomatsakis]

On Tue, Oct 21, 2014 at 03:57:17PM -0700, Daniel Micay wrote:

This interface has been removed.

Horray! (I'm late to the party; catching up on github notifications)