Typechecker can't pass copies to functions taking [const T]/&

[eholk]

Consider this code from base.rs:

        vec::riter(copy cleanups) {|cu|
            ...
        }

When I change riter to take a [const T]/&, I get the following error message:

/Users/eholk/Documents/projects/mozilla/rust/src/rustc/middle/trans/base.rs:4011:24: 4011:32 error: mismatched types: expected `[const <V10>]/&<R0>` but found `[middle::trans::common::cleanup]` (vector vs vector)
/Users/eholk/Documents/projects/mozilla/rust/src/rustc/middle/trans/base.rs:4011         vec::riter(copy cleanups) {|cu|
                                                                                                         ^~~~~~~~
error: aborting due to previous errors

These types should be coercible...

[nikomatsakis]

This may be nothing more than an artifact of the type inferencer, but I think it oughta' work... in particular I can't see why it would fix things to store copy cleanups into a temporary variable, but apparently it does.

[nikomatsakis]

I understand the problem now. It has to do w/ the limitation that we only perform borrowing for call args---the expected types then get passed down via copy and it requires a subtyping, not assignability, relationship.

[pcwalton]

Seems obsolete now. Please reopen if necessary.