Rollup of 8 pull requests

src/libcollections/str.rs

@@ -10,9 +10,28 @@
 
 //! Unicode string slices.
 //!
+//! The `&str` type is one of the two main string types, the other being `String`.
+//! Unlike its `String` counterpart, its contents are borrowed.
+//!
+//! # Basic Usage
+//!
+//! A basic string declaration of `&str` type:
+//!
+//! ```
+//! let hello_world = "Hello, World!";
+//! ```
+//!
+//! Here we have declared a string literal, also known as a string slice.
+//! String literals have a static lifetime, which means the string `hello_world`
+//! is guaranteed to be valid for the duration of the entire program.
+//! We can explicitly specify `hello_world`'s lifetime as well:
+//!
+//! ```
+//! let hello_world: &'static str = "Hello, world!";
+//! ```
+//!
 //! *[See also the `str` primitive type](../../std/primitive.str.html).*
 
-
 #![stable(feature = "rust1", since = "1.0.0")]
 
 // Many of the usings in this module are only used in the test configuration.

src/libcollections/vec.rs

@@ -1563,7 +1563,7 @@ impl<T> ops::DerefMut for Vec<T> {
 impl<T> FromIterator<T> for Vec<T> {
     #[inline]
     fn from_iter<I: IntoIterator<Item = T>>(iter: I) -> Vec<T> {
-        <Self as SpecExtend<_, _>>::from_iter(iter.into_iter())
+        <Self as SpecExtend<T, I::IntoIter>>::from_iter(iter.into_iter())
     }
 }
 
@@ -1631,7 +1631,7 @@ 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, iter: I) {
-        self.spec_extend(iter.into_iter())
+        <Self as SpecExtend<T, I::IntoIter>>::spec_extend(self, iter.into_iter())
     }
 }
 
@@ -1662,7 +1662,7 @@ impl<T, I> SpecExtend<T, I> for Vec<T>
                 vector
             }
         };
-        vector.spec_extend(iterator);
+        <Vec<T> as SpecExtend<T, I>>::spec_extend(&mut vector, iterator);
         vector
     }
 
@@ -1674,7 +1674,7 @@ impl<T, I> SpecExtend<T, I> for Vec<T>
 impl<T, I> SpecExtend<T, I> for Vec<T>
     where I: TrustedLen<Item=T>,
 {
-    fn from_iter(iterator: I) -> Self {
+    default fn from_iter(iterator: I) -> Self {
         let mut vector = Vec::new();
         vector.spec_extend(iterator);
         vector
@@ -1706,6 +1706,27 @@ impl<T, I> SpecExtend<T, I> for Vec<T>
     }
 }
 
+impl<T> SpecExtend<T, IntoIter<T>> for Vec<T> {
+    fn from_iter(iterator: IntoIter<T>) -> Self {
+        // A common case is passing a vector into a function which immediately
+        // re-collects into a vector. We can short circuit this if the IntoIter
+        // has not been advanced at all.
+        if *iterator.buf == iterator.ptr as *mut T {
+            unsafe {
+                let vec = Vec::from_raw_parts(*iterator.buf as *mut T,
+                                              iterator.len(),
+                                              iterator.cap);
+                mem::forget(iterator);
+                vec
+            }
+        } else {
+            let mut vector = Vec::new();
+            vector.spec_extend(iterator);
+            vector
+        }
+    }
+}
+
 impl<'a, T: 'a, I> SpecExtend<&'a T, I> for Vec<T>
     where I: Iterator<Item=&'a T>,
           T: Clone,

src/libcollectionstest/vec.rs

@@ -680,3 +680,19 @@ fn test_placement_panic() {
     let _ = panic::catch_unwind(panic::AssertUnwindSafe(|| { vec.place_back() <- mkpanic(); }));
     assert_eq!(vec.len(), 3);
 }
+
+#[test]
+fn from_into_inner() {
+    let vec = vec![1, 2, 3];
+    let ptr = vec.as_ptr();
+    let vec = vec.into_iter().collect::<Vec<_>>();
+    assert_eq!(vec, [1, 2, 3]);
+    assert_eq!(vec.as_ptr(), ptr);
+
+    let ptr = &vec[1] as *const _;
+    let mut it = vec.into_iter();
+    it.next().unwrap();
+    let vec = it.collect::<Vec<_>>();
+    assert_eq!(vec, [2, 3]);
+    assert!(ptr != vec.as_ptr());
+}

src/librustc/cfg/construct.rs

@@ -74,11 +74,11 @@ pub fn construct<'a, 'tcx>(tcx: TyCtxt<'a, 'tcx, 'tcx>,
 
 impl<'a, 'tcx> CFGBuilder<'a, 'tcx> {
     fn block(&mut self, blk: &hir::Block, pred: CFGIndex) -> CFGIndex {
-        if let Some(break_to_expr_id) = blk.break_to_expr_id {
+        if blk.targeted_by_break {
             let expr_exit = self.add_ast_node(blk.id, &[]);
 
             self.breakable_block_scopes.push(BlockScope {
-                block_expr_id: break_to_expr_id,
+                block_expr_id: blk.id,
                 break_index: expr_exit,
             });
 
@@ -195,7 +195,7 @@ impl<'a, 'tcx> CFGBuilder<'a, 'tcx> {
                 //   [..expr..]
                 //
                 let cond_exit = self.expr(&cond, pred);                // 1
-                let then_exit = self.block(&then, cond_exit);          // 2
+                let then_exit = self.expr(&then, cond_exit);          // 2
                 self.add_ast_node(expr.id, &[cond_exit, then_exit])      // 3,4
             }
 
@@ -215,7 +215,7 @@ impl<'a, 'tcx> CFGBuilder<'a, 'tcx> {
                 //   [..expr..]
                 //
                 let cond_exit = self.expr(&cond, pred);                // 1
-                let then_exit = self.block(&then, cond_exit);          // 2
+                let then_exit = self.expr(&then, cond_exit);          // 2
                 let else_exit = self.expr(&otherwise, cond_exit);      // 3
                 self.add_ast_node(expr.id, &[then_exit, else_exit])      // 4, 5
             }

src/librustc/hir/intravisit.rs

@@ -960,7 +960,7 @@ pub fn walk_expr<'v, V: Visitor<'v>>(visitor: &mut V, expression: &'v Expr) {
         }
         ExprIf(ref head_expression, ref if_block, ref optional_else) => {
             visitor.visit_expr(head_expression);
-            visitor.visit_block(if_block);
+            visitor.visit_expr(if_block);
             walk_list!(visitor, visit_expr, optional_else);
         }
         ExprWhile(ref subexpression, ref block, ref opt_sp_name) => {

src/librustc/hir/lowering.rs

@@ -1146,7 +1146,7 @@ impl<'a> LoweringContext<'a> {
         bounds.iter().map(|bound| self.lower_ty_param_bound(bound)).collect()
     }
 
-    fn lower_block(&mut self, b: &Block, break_to: Option<NodeId>) -> P<hir::Block> {
+    fn lower_block(&mut self, b: &Block, targeted_by_break: bool) -> P<hir::Block> {
         let mut expr = None;
 
         let mut stmts = vec![];
@@ -1169,7 +1169,7 @@ impl<'a> LoweringContext<'a> {
             expr: expr,
             rules: self.lower_block_check_mode(&b.rules),
             span: b.span,
-            break_to_expr_id: break_to,
+            targeted_by_break: targeted_by_break,
         })
     }
 
@@ -1264,7 +1264,7 @@ impl<'a> LoweringContext<'a> {
             }
             ItemKind::Fn(ref decl, unsafety, constness, abi, ref generics, ref body) => {
                 self.with_new_scopes(|this| {
-                    let body = this.lower_block(body, None);
+                    let body = this.lower_block(body, false);
                     let body = this.expr_block(body, ThinVec::new());
                     let body_id = this.record_body(body, Some(decl));
                     hir::ItemFn(this.lower_fn_decl(decl),
@@ -1358,7 +1358,7 @@ impl<'a> LoweringContext<'a> {
                                                    hir::TraitMethod::Required(names))
                     }
                     TraitItemKind::Method(ref sig, Some(ref body)) => {
-                        let body = this.lower_block(body, None);
+                        let body = this.lower_block(body, false);
                         let expr = this.expr_block(body, ThinVec::new());
                         let body_id = this.record_body(expr, Some(&sig.decl));
                         hir::TraitItemKind::Method(this.lower_method_sig(sig),
@@ -1414,7 +1414,7 @@ impl<'a> LoweringContext<'a> {
                         hir::ImplItemKind::Const(this.lower_ty(ty), body_id)
                     }
                     ImplItemKind::Method(ref sig, ref body) => {
-                        let body = this.lower_block(body, None);
+                        let body = this.lower_block(body, false);
                         let expr = this.expr_block(body, ThinVec::new());
                         let body_id = this.record_body(expr, Some(&sig.decl));
                         hir::ImplItemKind::Method(this.lower_method_sig(sig), body_id)
@@ -1838,32 +1838,35 @@ impl<'a> LoweringContext<'a> {
                                 id: id,
                                 rules: hir::DefaultBlock,
                                 span: span,
-                                break_to_expr_id: None,
+                                targeted_by_break: false,
                             });
                             P(self.expr_block(blk, ThinVec::new()))
                         }
                         _ => P(self.lower_expr(els)),
                     }
                 });
 
-                hir::ExprIf(P(self.lower_expr(cond)), self.lower_block(blk, None), else_opt)
+                let then_blk = self.lower_block(blk, false);
+                let then_expr = self.expr_block(then_blk, ThinVec::new());
+
+                hir::ExprIf(P(self.lower_expr(cond)), P(then_expr), else_opt)
             }
             ExprKind::While(ref cond, ref body, opt_ident) => {
                 self.with_loop_scope(e.id, |this|
                     hir::ExprWhile(
                         this.with_loop_condition_scope(|this| P(this.lower_expr(cond))),
-                        this.lower_block(body, None),
+                        this.lower_block(body, false),
                         this.lower_opt_sp_ident(opt_ident)))
             }
             ExprKind::Loop(ref body, opt_ident) => {
                 self.with_loop_scope(e.id, |this|
-                    hir::ExprLoop(this.lower_block(body, None),
+                    hir::ExprLoop(this.lower_block(body, false),
                                   this.lower_opt_sp_ident(opt_ident),
                                   hir::LoopSource::Loop))
             }
             ExprKind::Catch(ref body) => {
-                self.with_catch_scope(e.id, |this|
-                    hir::ExprBlock(this.lower_block(body, Some(e.id))))
+                self.with_catch_scope(body.id, |this|
+                    hir::ExprBlock(this.lower_block(body, true)))
             }
             ExprKind::Match(ref expr, ref arms) => {
                 hir::ExprMatch(P(self.lower_expr(expr)),
@@ -1881,7 +1884,7 @@ impl<'a> LoweringContext<'a> {
                     })
                 })
             }
-            ExprKind::Block(ref blk) => hir::ExprBlock(self.lower_block(blk, None)),
+            ExprKind::Block(ref blk) => hir::ExprBlock(self.lower_block(blk, false)),
             ExprKind::Assign(ref el, ref er) => {
                 hir::ExprAssign(P(self.lower_expr(el)), P(self.lower_expr(er)))
             }
@@ -2027,7 +2030,7 @@ impl<'a> LoweringContext<'a> {
 
                 // `<pat> => <body>`
                 {
-                    let body = self.lower_block(body, None);
+                    let body = self.lower_block(body, false);
                     let body_expr = P(self.expr_block(body, ThinVec::new()));
                     let pat = self.lower_pat(pat);
                     arms.push(self.arm(hir_vec![pat], body_expr));
@@ -2099,7 +2102,7 @@ impl<'a> LoweringContext<'a> {
                             let (guard, body) = if let ExprKind::If(ref cond,
                                                                     ref then,
                                                                     _) = else_expr.node {
-                                let then = self.lower_block(then, None);
+                                let then = self.lower_block(then, false);
                                 (Some(cond),
                                  self.expr_block(then, ThinVec::new()))
                             } else {
@@ -2149,7 +2152,7 @@ impl<'a> LoweringContext<'a> {
                 // Note that the block AND the condition are evaluated in the loop scope.
                 // This is done to allow `break` from inside the condition of the loop.
                 let (body, break_expr, sub_expr) = self.with_loop_scope(e.id, |this| (
-                    this.lower_block(body, None),
+                    this.lower_block(body, false),
                     this.expr_break(e.span, ThinVec::new()),
                     this.with_loop_condition_scope(|this| P(this.lower_expr(sub_expr))),
                 ));
@@ -2210,7 +2213,7 @@ impl<'a> LoweringContext<'a> {
                 // `::std::option::Option::Some(<pat>) => <body>`
                 let pat_arm = {
                     let body_block = self.with_loop_scope(e.id,
-                                                          |this| this.lower_block(body, None));
+                                                          |this| this.lower_block(body, false));
                     let body_expr = P(self.expr_block(body_block, ThinVec::new()));
                     let pat = self.lower_pat(pat);
                     let some_pat = self.pat_some(e.span, pat);
@@ -2642,7 +2645,7 @@ impl<'a> LoweringContext<'a> {
             id: self.next_id(),
             rules: hir::DefaultBlock,
             span: span,
-            break_to_expr_id: None,
+            targeted_by_break: false,
         }
     }
 
@@ -2750,7 +2753,7 @@ impl<'a> LoweringContext<'a> {
             id: id,
             stmts: stmts,
             expr: Some(expr),
-            break_to_expr_id: None,
+            targeted_by_break: false,
         });
         self.expr_block(block, attrs)
     }

src/librustc/hir/mod.rs

@@ -548,9 +548,11 @@ pub struct Block {
     /// Distinguishes between `unsafe { ... }` and `{ ... }`
     pub rules: BlockCheckMode,
     pub span: Span,
-    /// The id of the expression that `break` breaks to if the block can be broken out of.
-    /// Currently only `Some(_)` for `catch {}` blocks
-    pub break_to_expr_id: Option<NodeId>,
+    /// If true, then there may exist `break 'a` values that aim to
+    /// break out of this block early. As of this writing, this is not
+    /// currently permitted in Rust itself, but it is generated as
+    /// part of `catch` statements.
+    pub targeted_by_break: bool,
 }
 
 #[derive(Clone, PartialEq, Eq, RustcEncodable, RustcDecodable, Hash)]
@@ -992,8 +994,8 @@ pub enum Expr_ {
     ExprType(P<Expr>, P<Ty>),
     /// An `if` block, with an optional else block
     ///
-    /// `if expr { block } else { expr }`
-    ExprIf(P<Expr>, P<Block>, Option<P<Expr>>),
+    /// `if expr { expr } else { expr }`
+    ExprIf(P<Expr>, P<Expr>, Option<P<Expr>>),
     /// A while loop, with an optional label
     ///
     /// `'label: while expr { block }`

src/librustc/hir/print.rs

@@ -1036,7 +1036,7 @@ impl<'a> State<'a> {
                         word(&mut self.s, " else if ")?;
                         self.print_expr(&i)?;
                         space(&mut self.s)?;
-                        self.print_block(&then)?;
+                        self.print_expr(&then)?;
                         self.print_else(e.as_ref().map(|e| &**e))
                     }
                     // "final else"
@@ -1058,13 +1058,13 @@ impl<'a> State<'a> {
 
     pub fn print_if(&mut self,
                     test: &hir::Expr,
-                    blk: &hir::Block,
+                    blk: &hir::Expr,
                     elseopt: Option<&hir::Expr>)
                     -> io::Result<()> {
         self.head("if")?;
         self.print_expr(test)?;
         space(&mut self.s)?;
-        self.print_block(blk)?;
+        self.print_expr(blk)?;
         self.print_else(elseopt)
     }
 

src/librustc/infer/type_variable.rs

@@ -30,6 +30,7 @@ pub struct TypeVariableTable<'tcx> {
 }
 
 /// Reasons to create a type inference variable
+#[derive(Debug)]
 pub enum TypeVariableOrigin {
     MiscVariable(Span),
     NormalizeProjectionType(Span),
@@ -41,6 +42,7 @@ pub enum TypeVariableOrigin {
     AdjustmentType(Span),
     DivergingStmt(Span),
     DivergingBlockExpr(Span),
+    DivergingFn(Span),
     LatticeVariable(Span),
 }
 
@@ -196,14 +198,15 @@ impl<'tcx> TypeVariableTable<'tcx> {
                    diverging: bool,
                    origin: TypeVariableOrigin,
                    default: Option<Default<'tcx>>,) -> ty::TyVid {
+        debug!("new_var(diverging={:?}, origin={:?})", diverging, origin);
         self.eq_relations.new_key(());
         let index = self.values.push(TypeVariableData {
             value: Bounded { relations: vec![], default: default },
             origin: origin,
             diverging: diverging
         });
         let v = ty::TyVid { index: index as u32 };
-        debug!("new_var() -> {:?}", v);
+        debug!("new_var: diverging={:?} index={:?}", diverging, v);
         v
     }