Fix fallout in libsyntax from RFC 599. Clarity and efficiency seems to be mostly improved, to my eye.

Nonetheless, as this commit demonstrates, the previous commits was a [breaking-change].

In practice, breakage is focused on functions of this form:

```rust
fn foo(..., object: Box<FnMut()>)
````

where `FnMut()` could be any trait object type. The older scheme defaulted objects in argument
position so that they were bounded by a fresh lifetime:

```rust
fn foo<'a>(..., object: Box<FnMut()+'a>)
```

This meant that the object could contain borrowed data. The newer
scheme defaults to a lifetime bound of `'static`:

```rust
fn foo(..., object: Box<FnMut()+'static>)
```

This means that the object cannot contain borrowed data. In some cases, the best fix
is to stop using `Box`:

```rust
fn foo(..., object: &mut FnMut())
```

but another option is to write an explicit annotation for the `'a`
lifetime that used to be implicit.  Both fixes are demonstrated in
this commit.

1 files changed, 3 insertions, 3 deletions

diff --git a/src/libsyntax/ext/base.rs b/src/libsyntax/ext/base.rs
index 64ae6162ef4..083039995ee 100644
--- a/src/libsyntax/ext/base.rs
+++ b/src/libsyntax/ext/base.rs
@@ -35,18 +35,18 @@ pub trait ItemDecorator {
               sp: Span,
               meta_item: &ast::MetaItem,
               item: &ast::Item,
-              push: Box<FnMut(P<ast::Item>)>);
+              push: &mut FnMut(P<ast::Item>));
 }
 
 impl<F> ItemDecorator for F
-    where F : Fn(&mut ExtCtxt, Span, &ast::MetaItem, &ast::Item, Box<FnMut(P<ast::Item>)>)
+    where F : Fn(&mut ExtCtxt, Span, &ast::MetaItem, &ast::Item, &mut FnMut(P<ast::Item>))
 {
     fn expand(&self,
               ecx: &mut ExtCtxt,
               sp: Span,
               meta_item: &ast::MetaItem,
               item: &ast::Item,
-              push: Box<FnMut(P<ast::Item>)>) {
+              push: &mut FnMut(P<ast::Item>)) {
         (*self)(ecx, sp, meta_item, item, push)
     }
 }