Enabling recursion in Visitor.visit_ty makes the compiler reject fixed-length arrays

[alexcrichton]

It turns out that the compiler has a blank implementation of visit_ty (which does not recurse). The only relevant recursing is the visit_expr on the length of a fixed-length vector. If recursion is enabled (which I'm doing), the compiler dies all over the place because the expression doesn't have a type listed in the tcx.

For now I'm disabling recursion manually (to restore the old behavior), and tagging all relevant locations with this issue.

cc @nikomatsakis
cc @pnkfelix

[pnkfelix]

see also #10108

[alexcrichton]

Hm, that is a far better explanation. I'm currently landing this as part of #10862, so it sounds like everything is working as intended. Perhaps both bugs should be closed after that lands?

[pnkfelix]

@alexcrichton no objections here.

[nikomatsakis]

I agree recursion should be enabled by default. Can you point at the locations where you disabled recursion? it's quite possible that this is just the right thing to do in that instance.

[alexcrichton]

All of the relevant locations are tagged with a FIXME to this bug now that #10862 has landed.

I'm going to close the other bug for now, but leave this one open so it can track the blank visit_ty methods.

[steveklabnik]

rust/src/libsyntax/visit.rs

Line 76 in a0f86de

fn visit_ty(&mut self, t: &'v Ty) { walk_ty(self, t) }

<- I think this was fixed. And non of the visit_ty methods are blank now.

[ipetkov]

There is still a reference to this bug present in the source, namely the lint visitor: https://github.com/rust-lang/rust/blob/master/src/librustc/lint/context.rs#L645