auto merge of #20363 : japaric/rust/moar-uc, r=nmatsakis

The the last argument of the `ItemDecorator::expand` method has changed to `Box<FnMut>`. Syntax extensions will break.

[breaking-change]

---

This PR removes pretty much all the remaining uses of boxed closures from the libraries. There are still boxed closures under the `test` directory, but I think those should be removed or replaced with unboxed closures at the same time we remove boxed closures from the language.

In a few places I had to do some contortions (see the first commit for an example) to work around issue #19596. I have marked those workarounds with FIXMEs. In the future when `&mut F where F: FnMut` implements the `FnMut` trait, we should be able to remove those workarounds. I've take care to avoid placing the workaround functions in the public API.

Since `let f = || {}` always gets type checked as a boxed closure, I have explictly annotated those closures (with e.g. `|&:| {}`) to force the compiler to type check them as unboxed closures.

Instead of removing the type aliases (like `GetCrateDataCb`), I could have replaced them with newtypes. But this seemed like overcomplicating things for little to no gain.

I think we should be able to remove the boxed closures from the languge after this PR lands. (I'm being optimistic here)

r? @alexcrichton or @aturon 
cc @nikomatsakis 

1 files changed, 5 insertions, 5 deletions

diff --git a/src/libsyntax/parse/mod.rs b/src/libsyntax/parse/mod.rs
index 8cefb111fd1..88c485a07ac 100644
--- a/src/libsyntax/parse/mod.rs
+++ b/src/libsyntax/parse/mod.rs
@@ -240,7 +240,7 @@ pub fn new_parser_from_tts<'a>(sess: &'a ParseSess,
 /// add the path to the session's codemap and return the new filemap.
 pub fn file_to_filemap(sess: &ParseSess, path: &Path, spanopt: Option<Span>)
     -> Rc<FileMap> {
-    let err = |msg: &str| {
+    let err = |&: msg: &str| {
         match spanopt {
             Some(sp) => sess.span_diagnostic.span_fatal(sp, msg),
             None => sess.span_diagnostic.handler().fatal(msg),
@@ -399,7 +399,7 @@ pub fn char_lit(lit: &str) -> (char, int) {
         .map(|x| (x, len as int))
     }
 
-    let unicode_escape: || -> Option<(char, int)> = ||
+    let unicode_escape = |&: | -> Option<(char, int)>
         if lit.as_bytes()[2] == b'{' {
             let idx = lit.find('}').expect(msg2);
             let subslice = lit[3..idx];
@@ -426,7 +426,7 @@ pub fn str_lit(lit: &str) -> String {
     let mut res = String::with_capacity(lit.len());
 
     // FIXME #8372: This could be a for-loop if it didn't borrow the iterator
-    let error = |i| format!("lexer should have rejected {} at {}", lit, i);
+    let error = |&: i| format!("lexer should have rejected {} at {}", lit, i);
 
     /// Eat everything up to a non-whitespace
     fn eat<'a>(it: &mut iter::Peekable<(uint, char), str::CharIndices<'a>>) {
@@ -561,7 +561,7 @@ pub fn float_lit(s: &str, suffix: Option<&str>, sd: &SpanHandler, sp: Span) -> a
 
 /// Parse a string representing a byte literal into its final form. Similar to `char_lit`
 pub fn byte_lit(lit: &str) -> (u8, uint) {
-    let err = |i| format!("lexer accepted invalid byte literal {} step {}", lit, i);
+    let err = |&: i| format!("lexer accepted invalid byte literal {} step {}", lit, i);
 
     if lit.len() == 1 {
         (lit.as_bytes()[0], 1)
@@ -595,7 +595,7 @@ pub fn binary_lit(lit: &str) -> Rc<Vec<u8>> {
     let mut res = Vec::with_capacity(lit.len());
 
     // FIXME #8372: This could be a for-loop if it didn't borrow the iterator
-    let error = |i| format!("lexer should have rejected {} at {}", lit, i);
+    let error = |&: i| format!("lexer should have rejected {} at {}", lit, i);
 
     /// Eat everything up to a non-whitespace
     fn eat<'a, I: Iterator<(uint, u8)>>(it: &mut iter::Peekable<(uint, u8), I>) {