auto merge of #14250 : alexcrichton/rust/gc, r=brson

This commit removes `@T` from the compiler by moving the AST to using `Gc<T>`. This also starts treating `Gc<T>` as `@T` in the same way that `Box<T>` is the same as `~T` in the compiler.

After this hits a snapshot, the `@T` syntax should be able to be removed completely.

Author: bors

src/doc/tutorial.md

@@ -1710,14 +1710,14 @@ having ownership of the box. It allows the creation of cycles, and the individua
 not have a destructor.
 
 ~~~
-use std::gc::Gc;
+use std::gc::GC;
 
 // A fixed-size array allocated in a garbage-collected box
-let x = Gc::new([1, 2, 3, 4, 5, 6, 7, 8, 9, 10]);
+let x = box(GC) [1, 2, 3, 4, 5, 6, 7, 8, 9, 10];
 let y = x; // does not perform a move, unlike with `Rc`
 let z = x;
 
-assert!(*z.borrow() == [1, 2, 3, 4, 5, 6, 7, 8, 9, 10]);
+assert!(*z == [1, 2, 3, 4, 5, 6, 7, 8, 9, 10]);
 ~~~
 
 With shared ownership, mutability cannot be inherited so the boxes are always immutable. However,

src/liballoc/rc.rs

@@ -320,8 +320,8 @@ mod tests {
     #[test]
     fn gc_inside() {
         // see issue #11532
-        use std::gc::Gc;
-        let a = Rc::new(RefCell::new(Gc::new(1)));
+        use std::gc::GC;
+        let a = Rc::new(RefCell::new(box(GC) 1));
         assert!(a.try_borrow_mut().is_some());
     }
 

src/libcollections/hash/mod.rs

@@ -248,13 +248,6 @@ impl<S: Writer, T: Hash<S>> Hash<S> for Box<T> {
     }
 }
 
-impl<S: Writer, T: Hash<S>> Hash<S> for @T {
-    #[inline]
-    fn hash(&self, state: &mut S) {
-        (**self).hash(state);
-    }
-}
-
 impl<S: Writer, T: Hash<S>> Hash<S> for Rc<T> {
     #[inline]
     fn hash(&self, state: &mut S) {

src/libcore/clone.rs

@@ -39,12 +39,6 @@ pub trait Clone {
     }
 }
 
-impl<T> Clone for @T {
-    /// Return a shallow copy of the managed box.
-    #[inline]
-    fn clone(&self) -> @T { *self }
-}
-
 impl<'a, T> Clone for &'a T {
     /// Return a shallow copy of the reference.
     #[inline]
@@ -116,6 +110,7 @@ extern_fn_clone!(A, B, C, D, E, F, G, H)
 mod test {
     use prelude::*;
     use realstd::owned::Box;
+    use realstd::gc::{Gc, GC};
 
     fn realclone<T: ::realstd::clone::Clone>(t: &T) -> T {
         use realstd::clone::Clone;
@@ -136,9 +131,9 @@ mod test {
 
     #[test]
     fn test_managed_clone() {
-        let a = @5i;
-        let b: @int = a.clone();
-        assert_eq!(a, b);
+        let a = box(GC) 5i;
+        let b: Gc<int> = realclone(&a);
+        assert!(a == b);
     }
 
     #[test]

src/libcore/cmp.rs

@@ -326,29 +326,6 @@ mod impls {
         fn cmp(&self, other: &&'a mut T) -> Ordering { (**self).cmp(*other) }
     }
     impl<'a, T: Eq> Eq for &'a mut T {}
-
-    // @ pointers
-    impl<T:PartialEq> PartialEq for @T {
-        #[inline]
-        fn eq(&self, other: &@T) -> bool { *(*self) == *(*other) }
-        #[inline]
-        fn ne(&self, other: &@T) -> bool { *(*self) != *(*other) }
-    }
-    impl<T:PartialOrd> PartialOrd for @T {
-        #[inline]
-        fn lt(&self, other: &@T) -> bool { *(*self) < *(*other) }
-        #[inline]
-        fn le(&self, other: &@T) -> bool { *(*self) <= *(*other) }
-        #[inline]
-        fn ge(&self, other: &@T) -> bool { *(*self) >= *(*other) }
-        #[inline]
-        fn gt(&self, other: &@T) -> bool { *(*self) > *(*other) }
-    }
-    impl<T: Ord> Ord for @T {
-        #[inline]
-        fn cmp(&self, other: &@T) -> Ordering { (**self).cmp(*other) }
-    }
-    impl<T: Eq> Eq for @T {}
 }
 
 #[cfg(test)]

src/libcore/default.rs

@@ -43,7 +43,3 @@ default_impl!(i64, 0i64)
 
 default_impl!(f32, 0.0f32)
 default_impl!(f64, 0.0f64)
-
-impl<T: Default + 'static> Default for @T {
-    fn default() -> @T { @Default::default() }
-}

src/libcore/fmt/mod.rs

@@ -628,9 +628,6 @@ pub fn argumentuint<'a>(s: &'a uint) -> Argument<'a> {
 
 // Implementations of the core formatting traits
 
-impl<T: Show> Show for @T {
-    fn fmt(&self, f: &mut Formatter) -> Result { secret_show(&**self, f) }
-}
 impl<'a, T: Show> Show for &'a T {
     fn fmt(&self, f: &mut Formatter) -> Result { secret_show(*self, f) }
 }

src/libcore/raw.rs

@@ -79,7 +79,6 @@ pub trait Repr<T> {
 
 impl<'a, T> Repr<Slice<T>> for &'a [T] {}
 impl<'a> Repr<Slice<u8>> for &'a str {}
-impl<T> Repr<*Box<T>> for @T {}
 impl<T> Repr<*Vec<T>> for ~[T] {}
 
 #[cfg(test)]

src/librustc/driver/driver.rs

@@ -705,7 +705,7 @@ fn print_flowgraph<W:io::Writer>(analysis: CrateAnalysis,
                                  block: ast::P<ast::Block>,
                                  mut out: W) -> io::IoResult<()> {
     let ty_cx = &analysis.ty_cx;
-    let cfg = cfg::CFG::new(ty_cx, block);
+    let cfg = cfg::CFG::new(ty_cx, &*block);
     let lcfg = LabelledCFG { ast_map: &ty_cx.map,
                              cfg: &cfg,
                              name: format!("block{}", block.id).to_string(), };

src/librustc/front/config.rs

@@ -12,6 +12,8 @@ use syntax::fold::Folder;
 use syntax::{ast, fold, attr};
 use syntax::codemap;
 
+use std::gc::Gc;
+
 struct Context<'a> {
     in_cfg: |attrs: &[ast::Attribute]|: 'a -> bool,
 }
@@ -36,7 +38,7 @@ impl<'a> fold::Folder for Context<'a> {
     fn fold_item_underscore(&mut self, item: &ast::Item_) -> ast::Item_ {
         fold_item_underscore(self, item)
     }
-    fn fold_expr(&mut self, expr: @ast::Expr) -> @ast::Expr {
+    fn fold_expr(&mut self, expr: Gc<ast::Expr>) -> Gc<ast::Expr> {
         fold_expr(self, expr)
     }
 }
@@ -60,8 +62,8 @@ fn filter_view_item<'r>(cx: &mut Context, view_item: &'r ast::ViewItem)
 }
 
 fn fold_mod(cx: &mut Context, m: &ast::Mod) -> ast::Mod {
-    let filtered_items: Vec<&@ast::Item> = m.items.iter()
-            .filter(|&a| item_in_cfg(cx, *a))
+    let filtered_items: Vec<&Gc<ast::Item>> = m.items.iter()
+            .filter(|a| item_in_cfg(cx, &***a))
             .collect();
     let flattened_items = filtered_items.move_iter()
             .flat_map(|&x| cx.fold_item(x).move_iter())
@@ -76,9 +78,9 @@ fn fold_mod(cx: &mut Context, m: &ast::Mod) -> ast::Mod {
     }
 }
 
-fn filter_foreign_item(cx: &mut Context, item: @ast::ForeignItem)
-                       -> Option<@ast::ForeignItem> {
-    if foreign_item_in_cfg(cx, item) {
+fn filter_foreign_item(cx: &mut Context, item: Gc<ast::ForeignItem>)
+                       -> Option<Gc<ast::ForeignItem>> {
+    if foreign_item_in_cfg(cx, &*item) {
         Some(item)
     } else {
         None
@@ -103,7 +105,7 @@ fn fold_foreign_mod(cx: &mut Context, nm: &ast::ForeignMod) -> ast::ForeignMod {
 fn fold_item_underscore(cx: &mut Context, item: &ast::Item_) -> ast::Item_ {
     let item = match *item {
         ast::ItemImpl(ref a, ref b, c, ref methods) => {
-            let methods = methods.iter().filter(|m| method_in_cfg(cx, **m))
+            let methods = methods.iter().filter(|m| method_in_cfg(cx, &***m))
                 .map(|x| *x).collect();
             ast::ItemImpl((*a).clone(), (*b).clone(), c, methods)
         }
@@ -114,8 +116,8 @@ fn fold_item_underscore(cx: &mut Context, item: &ast::Item_) -> ast::Item_ {
                                  .collect();
             ast::ItemTrait((*a).clone(), b, (*c).clone(), methods)
         }
-        ast::ItemStruct(def, ref generics) => {
-            ast::ItemStruct(fold_struct(cx, def), generics.clone())
+        ast::ItemStruct(ref def, ref generics) => {
+            ast::ItemStruct(fold_struct(cx, &**def), generics.clone())
         }
         ast::ItemEnum(ref def, ref generics) => {
             let mut variants = def.variants.iter().map(|c| c.clone()).
@@ -125,11 +127,11 @@ fn fold_item_underscore(cx: &mut Context, item: &ast::Item_) -> ast::Item_ {
                 } else {
                     Some(match v.node.kind {
                                 ast::TupleVariantKind(..) => v,
-                                ast::StructVariantKind(def) => {
-                                    let def = fold_struct(cx, def);
-                                    @codemap::Spanned {
+                                ast::StructVariantKind(ref def) => {
+                                    let def = fold_struct(cx, &**def);
+                                    box(GC) codemap::Spanned {
                                         node: ast::Variant_ {
-                                            kind: ast::StructVariantKind(def),
+                                            kind: ast::StructVariantKind(def.clone()),
                                             ..v.node.clone()
                                         },
                                         ..*v
@@ -148,24 +150,24 @@ fn fold_item_underscore(cx: &mut Context, item: &ast::Item_) -> ast::Item_ {
     fold::noop_fold_item_underscore(&item, cx)
 }
 
-fn fold_struct(cx: &mut Context, def: &ast::StructDef) -> @ast::StructDef {
+fn fold_struct(cx: &mut Context, def: &ast::StructDef) -> Gc<ast::StructDef> {
     let mut fields = def.fields.iter().map(|c| c.clone()).filter(|m| {
         (cx.in_cfg)(m.node.attrs.as_slice())
     });
-    @ast::StructDef {
+    box(GC) ast::StructDef {
         fields: fields.collect(),
         ctor_id: def.ctor_id,
         super_struct: def.super_struct.clone(),
         is_virtual: def.is_virtual,
     }
 }
 
-fn retain_stmt(cx: &mut Context, stmt: @ast::Stmt) -> bool {
+fn retain_stmt(cx: &mut Context, stmt: Gc<ast::Stmt>) -> bool {
     match stmt.node {
       ast::StmtDecl(decl, _) => {
         match decl.node {
-          ast::DeclItem(item) => {
-            item_in_cfg(cx, item)
+          ast::DeclItem(ref item) => {
+            item_in_cfg(cx, &**item)
           }
           _ => true
         }
@@ -175,10 +177,10 @@ fn retain_stmt(cx: &mut Context, stmt: @ast::Stmt) -> bool {
 }
 
 fn fold_block(cx: &mut Context, b: ast::P<ast::Block>) -> ast::P<ast::Block> {
-    let resulting_stmts: Vec<&@ast::Stmt> =
+    let resulting_stmts: Vec<&Gc<ast::Stmt>> =
         b.stmts.iter().filter(|&a| retain_stmt(cx, *a)).collect();
     let resulting_stmts = resulting_stmts.move_iter()
-        .flat_map(|&stmt| cx.fold_stmt(stmt).move_iter())
+        .flat_map(|stmt| cx.fold_stmt(&**stmt).move_iter())
         .collect();
     let filtered_view_items = b.view_items.iter().filter_map(|a| {
         filter_view_item(cx, a).map(|x| cx.fold_view_item(x))
@@ -193,14 +195,14 @@ fn fold_block(cx: &mut Context, b: ast::P<ast::Block>) -> ast::P<ast::Block> {
     })
 }
 
-fn fold_expr(cx: &mut Context, expr: @ast::Expr) -> @ast::Expr {
+fn fold_expr(cx: &mut Context, expr: Gc<ast::Expr>) -> Gc<ast::Expr> {
     let expr = match expr.node {
         ast::ExprMatch(ref m, ref arms) => {
             let arms = arms.iter()
                 .filter(|a| (cx.in_cfg)(a.attrs.as_slice()))
                 .map(|a| a.clone())
                 .collect();
-            @ast::Expr {
+            box(GC) ast::Expr {
                 id: expr.id,
                 span: expr.span.clone(),
                 node: ast::ExprMatch(m.clone(), arms),
@@ -236,7 +238,7 @@ fn trait_method_in_cfg(cx: &mut Context, meth: &ast::TraitMethod) -> bool {
 
 // Determine if an item should be translated in the current crate
 // configuration based on the item's attributes
-fn in_cfg(cfg: &[@ast::MetaItem], attrs: &[ast::Attribute]) -> bool {
+fn in_cfg(cfg: &[Gc<ast::MetaItem>], attrs: &[ast::Attribute]) -> bool {
     attr::test_cfg(cfg, attrs.iter().map(|x| *x))
 }