Constants for mutability that are useful for visitor api are in libsyntax

[dbp]

This is not good, as it means anything that wants to use the visitor api (for example, I'm working on having fmt! "%?" use it) would depend on libsyntax.

[brson]

Which constants?

[dbp]

Sorry I should have clarified what I meant by "Constants for mutability": In syntax/ast.rs:

181: enum mutability { m_mutbl, m_imm, m_const, }

The reason why this is an issue is that there are functions in the reflection api, like for example:

fn visit_rec_field(_i: uint, _name: &str,  _mtbl: uint, inner: *tydesc) -> bool

where _mtbl is the uint value of that enum. This actually really confused me at first, because I figured it was a boolean cast as a uint, but 0 was mutable, and 1 was immutable (and 2 const, but I don't think that's relevant for record fields?)! Ideally the visitor api would actually have the function have this signature:

fn visit_rec_field(_i: uint, _name: &str,  _mtbl: mutability, inner: *tydesc) -> bool

And mutability would live somewhere that could be included by core::reflect (once that exists) as well as libsyntax.

There may be other constants like this as well - I've only just started working with the api.

[catamorphism]

Not critical for 0.6; de-milestoning

[emberian]

I don't think this is worth fixing; it looks to me like the TyVisitor needs some serious love (it has methods like visit_class_field), and any changes to it would ideally use a safer interface than magic numbers.

[thestinger]

I don't think this will be a problem, because const is being removed. We can switch the mtbl parameter to a simple bool.