---

yaml
---
r: 227575
b: refs/heads/try
c: 5a63326
h: refs/heads/master
i:
  227573: 6c07bc6
  227571: 81980b1
  227567: 635c8e4
v: v3

Author: steveklabnik

[refs]

@@ -1,7 +1,7 @@
 ---
 refs/heads/master: aca2057ed5fb7af3f8905b2bc01f72fa001c35c8
 refs/heads/snap-stage3: 1af31d4974e33027a68126fa5a5a3c2c6491824f
-refs/heads/try: b780bc513c416840ef7da3580b50248e4af07659
+refs/heads/try: 5a63326442fe068c63dcd7cdd60ca6be25ce666a
 refs/tags/release-0.1: 1f5c5126e96c79d22cb7862f75304136e204f105
 refs/tags/release-0.2: c870d2dffb391e14efb05aa27898f1f6333a9596
 refs/tags/release-0.3: b5f0d0f648d9a6153664837026ba1be43d3e2503

branches/try/src/doc/reference.md

@@ -638,7 +638,7 @@ apply to the crate as a whole.
 ```
 
 A crate that contains a `main` function can be compiled to an executable. If a
-`main` function is present, its return type must be [`unit`](#tuple-types)
+`main` function is present, its return type must be [`unit`](#primitive-types)
 and it must take no arguments.
 
 # Items and attributes
@@ -944,9 +944,20 @@ fn foo<T>(x: T) where T: Debug {
 ```
 
 When a generic function is referenced, its type is instantiated based on the
-context of the reference. For example, calling the `iter` function defined
-above on `[1, 2]` will instantiate type parameter `T` with `i32`, and require
-the closure parameter to have type `Fn(i32)`.
+context of the reference. For example, calling the `foo` function here:
+
+```
+use std::fmt::Debug;
+
+fn foo<T>(x: &[T]) where T: Debug {
+    // details elided
+    # ()
+}
+
+foo(&[1, 2]);
+```
+
+will instantiate type parameter `T` with `i32`.
 
 The type parameters can also be explicitly supplied in a trailing
 [path](#paths) component after the function name. This might be necessary if
@@ -2873,7 +2884,7 @@ The `+`, `-`, `*`, `/`, `%`, `&`, `|`, `^`, `<<`, and `>>` operators may be
 composed with the `=` operator. The expression `lval OP= val` is equivalent to
 `lval = lval OP val`. For example, `x = x + 1` may be written as `x += 1`.
 
-Any such expression always has the [`unit`](#tuple-types) type.
+Any such expression always has the [`unit`](#primitive-types) type.
 
 #### Operator precedence
 
@@ -3315,9 +3326,6 @@ assert!(b != "world");
 assert!(p.0 == 10);
 ```
 
-For historical reasons and convenience, the tuple type with no elements (`()`)
-is often called ‘unit’ or ‘the unit type’.
-
 ### Array, and Slice types
 
 Rust has two different types for a list of items:

branches/try/src/doc/trpl/traits.md

@@ -332,7 +332,7 @@ fn normal<T: ConvertTo<i64>>(x: &T) -> i64 {
 fn inverse<T>() -> T
         // this is using ConvertTo as if it were "ConvertFrom<i32>"
         where i32: ConvertTo<T> {
-    42.convert()
+    1i32.convert()
 }
 ```
 

branches/try/src/libcollections/vec.rs

@@ -1469,26 +1469,42 @@ impl<T> ops::DerefMut for Vec<T> {
 impl<T> FromIterator<T> for Vec<T> {
     #[inline]
     fn from_iter<I: IntoIterator<Item=T>>(iterable: I) -> Vec<T> {
-        // Unroll the first iteration, as the vector is going to be
-        // expanded on this iteration in every case when the iterable is not
-        // empty, but the loop in extend_desugared() is not going to see the
-        // vector being full in the few subsequent loop iterations.
-        // So we get better branch prediction and the possibility to
-        // construct the vector with initial estimated capacity.
         let mut iterator = iterable.into_iter();
-        let mut vector = match iterator.next() {
-            None => return Vec::new(),
-            Some(element) => {
-                let (lower, _) = iterator.size_hint();
-                let mut vector = Vec::with_capacity(1 + lower);
-                unsafe {
-                    ptr::write(vector.get_unchecked_mut(0), element);
-                    vector.set_len(1);
-                }
-                vector
+        let (lower, _) = iterator.size_hint();
+        let mut vector = Vec::with_capacity(lower);
+
+        // This function should be the moral equivalent of:
+        //
+        //      for item in iterator {
+        //          vector.push(item);
+        //      }
+        //
+        // This equivalent crucially runs the iterator precisely once. Below we
+        // actually in theory run the iterator twice (one without bounds checks
+        // and one with). To achieve the "moral equivalent", we use the `if`
+        // statement below to break out early.
+        //
+        // If the first loop has terminated, then we have one of two conditions.
+        //
+        // 1. The underlying iterator returned `None`. In this case we are
+        //    guaranteed that less than `vector.capacity()` elements have been
+        //    returned, so we break out early.
+        // 2. The underlying iterator yielded `vector.capacity()` elements and
+        //    has not yielded `None` yet. In this case we run the iterator to
+        //    its end below.
+        for element in iterator.by_ref().take(vector.capacity()) {
+            let len = vector.len();
+            unsafe {
+                ptr::write(vector.get_unchecked_mut(len), element);
+                vector.set_len(len + 1);
+            }
+        }
+
+        if vector.len() == vector.capacity() {
+            for element in iterator {
+                vector.push(element);
             }
-        };
-        vector.extend_desugared(iterator);
+        }
         vector
     }
 }
@@ -1553,27 +1569,11 @@ impl<'a, T> IntoIterator for &'a mut Vec<T> {
 impl<T> Extend<T> for Vec<T> {
     #[inline]
     fn extend<I: IntoIterator<Item=T>>(&mut self, iterable: I) {
-        self.extend_desugared(iterable.into_iter())
-    }
-}
-
-impl<T> Vec<T> {
-    fn extend_desugared<I: Iterator<Item=T>>(&mut self, mut iterator: I) {
-        // This function should be the moral equivalent of:
-        //
-        //      for item in iterator {
-        //          self.push(item);
-        //      }
-        while let Some(element) = iterator.next() {
-            let len = self.len();
-            if len == self.capacity() {
-                let (lower, _) = iterator.size_hint();
-                self.reserve(lower + 1);
-            }
-            unsafe {
-                ptr::write(self.get_unchecked_mut(len), element);
-                self.set_len(len + 1);
-            }
+        let iterator = iterable.into_iter();
+        let (lower, _) = iterator.size_hint();
+        self.reserve(lower);
+        for element in iterator {
+            self.push(element)
         }
     }
 }

branches/try/src/libcore/char.rs

@@ -74,8 +74,17 @@ pub const MAX: char = '\u{10ffff}';
 /// ```
 /// use std::char;
 ///
-/// assert_eq!(char::from_u32(0x2764), Some('❤'));
-/// assert_eq!(char::from_u32(0x110000), None); // invalid character
+/// let c = char::from_u32(10084); // produces `Some(❤)`
+/// assert_eq!(c, Some('❤'));
+/// ```
+///
+/// An invalid character:
+///
+/// ```
+/// use std::char;
+///
+/// let none = char::from_u32(1114112);
+/// assert_eq!(none, None);
 /// ```
 #[inline]
 #[stable(feature = "rust1", since = "1.0.0")]

branches/try/src/librustc/middle/check_const.rs

@@ -285,7 +285,7 @@ impl<'a, 'tcx> CheckCrateVisitor<'a, 'tcx> {
     fn check_static_type(&self, e: &ast::Expr) {
         let ty = ty::node_id_to_type(self.tcx, e.id);
         let infcx = infer::new_infer_ctxt(self.tcx);
-        let mut fulfill_cx = traits::FulfillmentContext::new(false);
+        let mut fulfill_cx = traits::FulfillmentContext::new();
         let cause = traits::ObligationCause::new(e.span, e.id, traits::SharedStatic);
         fulfill_cx.register_builtin_bound(&infcx, ty, ty::BoundSync, cause);
         let env = ty::empty_parameter_environment(self.tcx);

branches/try/src/librustc/middle/dead.rs

@@ -48,7 +48,6 @@ struct MarkSymbolVisitor<'a, 'tcx: 'a> {
     struct_has_extern_repr: bool,
     ignore_non_const_paths: bool,
     inherited_pub_visibility: bool,
-    ignore_variant_stack: Vec<ast::NodeId>,
 }
 
 impl<'a, 'tcx> MarkSymbolVisitor<'a, 'tcx> {
@@ -61,7 +60,6 @@ impl<'a, 'tcx> MarkSymbolVisitor<'a, 'tcx> {
             struct_has_extern_repr: false,
             ignore_non_const_paths: false,
             inherited_pub_visibility: false,
-            ignore_variant_stack: vec![],
         }
     }
 
@@ -82,9 +80,7 @@ impl<'a, 'tcx> MarkSymbolVisitor<'a, 'tcx> {
                 def::DefPrimTy(_) => (),
                 def::DefVariant(enum_id, variant_id, _) => {
                     self.check_def_id(enum_id);
-                    if !self.ignore_variant_stack.contains(&variant_id.node) {
-                        self.check_def_id(variant_id);
-                    }
+                    self.check_def_id(variant_id);
                 }
                 _ => {
                     self.check_def_id(def.def_id());
@@ -276,23 +272,6 @@ impl<'a, 'tcx, 'v> Visitor<'v> for MarkSymbolVisitor<'a, 'tcx> {
         visit::walk_expr(self, expr);
     }
 
-    fn visit_arm(&mut self, arm: &ast::Arm) {
-        if arm.pats.len() == 1 {
-            let pat = &*arm.pats[0];
-            let variants = pat_util::necessary_variants(&self.tcx.def_map, pat);
-
-            // Inside the body, ignore constructions of variants
-            // necessary for the pattern to match. Those construction sites
-            // can't be reached unless the variant is constructed elsewhere.
-            let len = self.ignore_variant_stack.len();
-            self.ignore_variant_stack.push_all(&*variants);
-            visit::walk_arm(self, arm);
-            self.ignore_variant_stack.truncate(len);
-        } else {
-            visit::walk_arm(self, arm);
-        }
-    }
-
     fn visit_pat(&mut self, pat: &ast::Pat) {
         let def_map = &self.tcx.def_map;
         match pat.node {
@@ -414,11 +393,6 @@ fn create_and_seed_worklist(tcx: &ty::ctxt,
         worklist.push(*id);
     }
     for id in reachable_symbols {
-        // Reachable variants can be dead, because we warn about
-        // variants never constructed, not variants never used.
-        if let Some(ast_map::NodeVariant(..)) = tcx.map.find(*id) {
-            continue;
-        }
         worklist.push(*id);
     }
 

branches/try/src/librustc/middle/pat_util.rs

@@ -201,27 +201,3 @@ pub fn def_to_path(tcx: &ty::ctxt, id: ast::DefId) -> ast::Path {
         span: DUMMY_SP,
     })
 }
-
-/// Return variants that are necessary to exist for the pattern to match.
-pub fn necessary_variants(dm: &DefMap, pat: &ast::Pat) -> Vec<ast::NodeId> {
-    let mut variants = vec![];
-    walk_pat(pat, |p| {
-        match p.node {
-            ast::PatEnum(_, _) |
-            ast::PatIdent(_, _, None) |
-            ast::PatStruct(..) => {
-                match dm.borrow().get(&p.id) {
-                    Some(&PathResolution { base_def: DefVariant(_, id, _), .. }) => {
-                        variants.push(id.node);
-                    }
-                    _ => ()
-                }
-            }
-            _ => ()
-        }
-        true
-    });
-    variants.sort();
-    variants.dedup();
-    variants
-}