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

Author: bors

src/libcollections/str.rs

@@ -202,7 +202,7 @@ impl<'a> Iterator<char> for Decompositions<'a> {
                 let buffer = &mut self.buffer;
                 let sorted = &mut self.sorted;
                 {
-                    let callback = |d| {
+                    let callback = |&mut: d| {
                         let class =
                             unicode::char::canonical_combining_class(d);
                         if class == 0 && !*sorted {

src/libcore/fmt/float.rs

@@ -225,10 +225,10 @@ pub fn float_to_str_bytes_common<T: Float, U, F>(
         // cut off the one extra digit, and depending on its value
         // round the remaining ones.
         if limit_digits && dig == digit_count {
-            let ascii2value = |chr: u8| {
+            let ascii2value = |&: chr: u8| {
                 (chr as char).to_digit(radix).unwrap()
             };
-            let value2ascii = |val: uint| {
+            let value2ascii = |&: val: uint| {
                 char::from_digit(val, radix).unwrap() as u8
             };
 

src/libcore/fmt/mod.rs

@@ -398,7 +398,7 @@ impl<'a> Formatter<'a> {
         }
 
         // Writes the sign if it exists, and then the prefix if it was requested
-        let write_prefix = |f: &mut Formatter| {
+        let write_prefix = |&: f: &mut Formatter| {
             for c in sign.into_iter() {
                 let mut b = [0, ..4];
                 let n = c.encode_utf8(&mut b).unwrap_or(0);

src/libgetopts/lib.rs

@@ -875,7 +875,7 @@ fn each_split_within<F>(ss: &str, lim: uint, mut it: F) -> bool where
         lim = fake_i;
     }
 
-    let machine: |&mut bool, (uint, char)| -> bool = |cont, (i, c)| {
+    let mut machine = |&mut: cont: &mut bool, (i, c): (uint, char)| -> bool {
         let whitespace = if c.is_whitespace() { Ws }       else { Cr };
         let limit      = if (i - slice_start + 1) <= lim  { UnderLim } else { OverLim };
 

src/librustc/metadata/creader.rs

@@ -177,7 +177,7 @@ fn extract_crate_info(e: &Env, i: &ast::ViewItem) -> Option<CrateInfo> {
 }
 
 pub fn validate_crate_name(sess: Option<&Session>, s: &str, sp: Option<Span>) {
-    let err = |s: &str| {
+    let err = |&: s: &str| {
         match (sp, sess) {
             (_, None) => panic!("{}", s),
             (Some(sp), Some(sess)) => sess.span_err(sp, s),

src/librustc/metadata/csearch.rs

@@ -62,7 +62,7 @@ pub fn each_child_of_item<F>(cstore: &cstore::CStore,
     F: FnMut(decoder::DefLike, ast::Name, ast::Visibility),
 {
     let crate_data = cstore.get_crate_data(def_id.krate);
-    let get_crate_data: decoder::GetCrateDataCb = |cnum| {
+    let get_crate_data = |&mut: cnum| {
         cstore.get_crate_data(cnum)
     };
     decoder::each_child_of_item(cstore.intr.clone(),
@@ -79,7 +79,7 @@ pub fn each_top_level_item_of_crate<F>(cstore: &cstore::CStore,
     F: FnMut(decoder::DefLike, ast::Name, ast::Visibility),
 {
     let crate_data = cstore.get_crate_data(cnum);
-    let get_crate_data: decoder::GetCrateDataCb = |cnum| {
+    let get_crate_data = |&mut: cnum| {
         cstore.get_crate_data(cnum)
     };
     decoder::each_top_level_item_of_crate(cstore.intr.clone(),

src/librustc/metadata/decoder.rs

@@ -487,14 +487,13 @@ pub fn each_lang_item<F>(cdata: Cmd, mut f: F) -> bool where
     })
 }
 
-pub type GetCrateDataCb<'a> = |ast::CrateNum|: 'a -> Rc<crate_metadata>;
-
-fn each_child_of_item_or_crate<F>(intr: Rc<IdentInterner>,
-                                  cdata: Cmd,
-                                  item_doc: rbml::Doc,
-                                  get_crate_data: GetCrateDataCb,
-                                  mut callback: F) where
+fn each_child_of_item_or_crate<F, G>(intr: Rc<IdentInterner>,
+                                     cdata: Cmd,
+                                     item_doc: rbml::Doc,
+                                     mut get_crate_data: G,
+                                     mut callback: F) where
     F: FnMut(DefLike, ast::Name, ast::Visibility),
+    G: FnMut(ast::CrateNum) -> Rc<crate_metadata>,
 {
     // Iterate over all children.
     let _ = reader::tagged_docs(item_doc, tag_mod_child, |child_info_doc| {
@@ -608,12 +607,13 @@ fn each_child_of_item_or_crate<F>(intr: Rc<IdentInterner>,
 }
 
 /// Iterates over each child of the given item.
-pub fn each_child_of_item<F>(intr: Rc<IdentInterner>,
-                             cdata: Cmd,
-                             id: ast::NodeId,
-                             get_crate_data: GetCrateDataCb,
-                             callback: F) where
+pub fn each_child_of_item<F, G>(intr: Rc<IdentInterner>,
+                               cdata: Cmd,
+                               id: ast::NodeId,
+                               get_crate_data: G,
+                               callback: F) where
     F: FnMut(DefLike, ast::Name, ast::Visibility),
+    G: FnMut(ast::CrateNum) -> Rc<crate_metadata>,
 {
     // Find the item.
     let root_doc = rbml::Doc::new(cdata.data());
@@ -631,11 +631,12 @@ pub fn each_child_of_item<F>(intr: Rc<IdentInterner>,
 }
 
 /// Iterates over all the top-level crate items.
-pub fn each_top_level_item_of_crate<F>(intr: Rc<IdentInterner>,
-                                       cdata: Cmd,
-                                       get_crate_data: GetCrateDataCb,
-                                       callback: F) where
+pub fn each_top_level_item_of_crate<F, G>(intr: Rc<IdentInterner>,
+                                          cdata: Cmd,
+                                          get_crate_data: G,
+                                          callback: F) where
     F: FnMut(DefLike, ast::Name, ast::Visibility),
+    G: FnMut(ast::CrateNum) -> Rc<crate_metadata>,
 {
     let root_doc = rbml::Doc::new(cdata.data());
     let misc_info_doc = reader::get_doc(root_doc, tag_misc_info);

src/librustc/metadata/encoder.rs

@@ -1418,7 +1418,7 @@ fn encode_info_for_item(ecx: &EncodeContext,
             encode_parent_sort(rbml_w, 't');
 
             let trait_item = &ms[i];
-            let encode_trait_item = |rbml_w: &mut Encoder| {
+            let encode_trait_item = |&: rbml_w: &mut Encoder| {
                 // If this is a static method, we've already
                 // encoded this.
                 if is_nonstatic_method {

src/librustc/metadata/filesearch.rs

@@ -30,10 +30,6 @@ pub enum FileMatch {
 // FIXME (#2658): I'm not happy how this module turned out. Should
 // probably just be folded into cstore.
 
-/// Functions with type `pick` take a parent directory as well as
-/// a file found in that directory.
-pub type pick<'a> = |path: &Path|: 'a -> FileMatch;
-
 pub struct FileSearch<'a> {
     pub sysroot: &'a Path,
     pub search_paths: &'a SearchPaths,
@@ -95,7 +91,7 @@ impl<'a> FileSearch<'a> {
         make_target_lib_path(self.sysroot, self.triple)
     }
 
-    pub fn search(&self, pick: pick) {
+    pub fn search<F>(&self, mut pick: F) where F: FnMut(&Path) -> FileMatch {
         self.for_each_lib_search_path(|lib_search_path| {
             debug!("searching {}", lib_search_path.display());
             match fs::readdir(lib_search_path) {

src/librustc/middle/check_const.rs

@@ -185,7 +185,7 @@ fn check_expr(v: &mut CheckCrateVisitor, e: &ast::Expr) -> bool {
         ast::ExprBlock(ref block) => {
             // Check all statements in the block
             for stmt in block.stmts.iter() {
-                let block_span_err = |span|
+                let block_span_err = |&: span|
                     span_err!(v.tcx.sess, span, E0016,
                               "blocks in constants are limited to items and \
                                tail expressions");