---

yaml
---
r: 275993
b: refs/heads/master
c: b9dd8aa
h: refs/heads/master
i:
  275991: 884c337

Author: steveklabnik

[refs]

@@ -1,5 +1,5 @@
 ---
-refs/heads/master: e6b9760df21f580e8210f97c01a957a91eeb91b5
+refs/heads/master: b9dd8aa4c291ce464655735802e68b26fe9c6862
 refs/heads/snap-stage3: 235d77457d80b549dad3ac36d94f235208a1eafb
 refs/heads/try: 49312a405e14a449b98fe0056b12a40ac128be4a
 refs/tags/release-0.1: 1f5c5126e96c79d22cb7862f75304136e204f105

trunk/src/doc/book/lifetimes.md

@@ -1,7 +1,7 @@
 % Lifetimes
 
-This guide is three of three presenting Rust’s ownership system. This is one of
-Rust’s most unique and compelling features, with which Rust developers should
+This is the last of three sections presenting Rust’s ownership system. This is one of
+Rust’s most distinct and compelling features, with which Rust developers should
 become quite acquainted. Ownership is how Rust achieves its largest goal,
 memory safety. There are a few distinct concepts, each with its own chapter:
 

trunk/src/doc/book/ownership.md

@@ -1,7 +1,7 @@
 % Ownership
 
-This guide is one of three presenting Rust’s ownership system. This is one of
-Rust’s most unique and compelling features, with which Rust developers should
+This is the first of three sections presenting Rust’s ownership system. This is one of
+Rust’s most distinct and compelling features, with which Rust developers should
 become quite acquainted. Ownership is how Rust achieves its largest goal,
 memory safety. There are a few distinct concepts, each with its own
 chapter:

trunk/src/doc/book/references-and-borrowing.md

@@ -1,7 +1,7 @@
 % References and Borrowing
 
-This guide is two of three presenting Rust’s ownership system. This is one of
-Rust’s most unique and compelling features, with which Rust developers should
+This is the second of three sections presenting Rust’s ownership system. This is one of
+Rust’s most distinct and compelling features, with which Rust developers should
 become quite acquainted. Ownership is how Rust achieves its largest goal,
 memory safety. There are a few distinct concepts, each with its own
 chapter:
@@ -77,6 +77,32 @@ let answer = foo(&v1, &v2);
 // we can use v1 and v2 here!
 ```
 
+A more concrete example:
+
+```rust
+fn main() {
+    // Don't worry if you don't understand how `fold` works, the point here is that an immutable reference is borrowed.
+    fn sum_vec(v: &Vec<i32>) -> i32 {
+        return v.iter().fold(0, |a, &b| a + b);
+    }
+    // Borrow two vectors and and sum them.
+    // This kind of borrowing does not allow mutation to the borrowed.
+    fn foo(v1: &Vec<i32>, v2: &Vec<i32>) -> i32 {
+        // do stuff with v1 and v2
+        let s1 = sum_vec(v1);
+        let s2 = sum_vec(v2);
+        // return the answer
+        s1 + s2
+    }
+
+    let v1 = vec![1, 2, 3];
+    let v2 = vec![4, 5, 6];
+
+    let answer = foo(&v1, &v2);
+    println!("{}", answer);
+}
+```
+
 Instead of taking `Vec<i32>`s as our arguments, we take a reference:
 `&Vec<i32>`. And instead of passing `v1` and `v2` directly, we pass `&v1` and
 `&v2`. We call the `&T` type a ‘reference’, and rather than owning the resource,

trunk/src/libcore/ptr.rs

@@ -459,6 +459,9 @@ impl<T: ?Sized> *mut T {
     /// ```
     /// let mut s = [1, 2, 3];
     /// let ptr: *mut u32 = s.as_mut_ptr();
+    /// let first_value = unsafe { ptr.as_mut().unwrap() };
+    /// *first_value = 4;
+    /// println!("{:?}", s); // It'll print: "[4, 2, 3]".
     /// ```
     #[stable(feature = "ptr_as_ref", since = "1.9.0")]
     #[inline]

trunk/src/librustc/infer/error_reporting.rs

@@ -157,7 +157,7 @@ impl<'tcx> TyCtxt<'tcx> {
                         "scope of call-site for function"
                     }
                     region::CodeExtentData::ParameterScope { .. } => {
-                        "scope of parameters for function"
+                        "scope of function body"
                     }
                     region::CodeExtentData::DestructionScope(_) => {
                         new_string = format!("destruction scope surrounding {}", tag);

trunk/src/librustc_const_eval/eval.rs

@@ -562,44 +562,51 @@ pub fn eval_const_expr_partial<'tcx>(tcx: &TyCtxt<'tcx>,
     let result = match e.node {
       hir::ExprUnary(hir::UnNeg, ref inner) => {
         // unary neg literals already got their sign during creation
-        if let hir::ExprLit(ref lit) = inner.node {
-            use syntax::ast::*;
-            use syntax::ast::LitIntType::*;
-            const I8_OVERFLOW: u64 = ::std::i8::MAX as u64 + 1;
-            const I16_OVERFLOW: u64 = ::std::i16::MAX as u64 + 1;
-            const I32_OVERFLOW: u64 = ::std::i32::MAX as u64 + 1;
-            const I64_OVERFLOW: u64 = ::std::i64::MAX as u64 + 1;
-            match (&lit.node, ety.map(|t| &t.sty)) {
-                (&LitKind::Int(I8_OVERFLOW, Unsuffixed), Some(&ty::TyInt(IntTy::I8))) |
-                (&LitKind::Int(I8_OVERFLOW, Signed(IntTy::I8)), _) => {
-                    return Ok(Integral(I8(::std::i8::MIN)))
-                },
-                (&LitKind::Int(I16_OVERFLOW, Unsuffixed), Some(&ty::TyInt(IntTy::I16))) |
-                (&LitKind::Int(I16_OVERFLOW, Signed(IntTy::I16)), _) => {
-                    return Ok(Integral(I16(::std::i16::MIN)))
-                },
-                (&LitKind::Int(I32_OVERFLOW, Unsuffixed), Some(&ty::TyInt(IntTy::I32))) |
-                (&LitKind::Int(I32_OVERFLOW, Signed(IntTy::I32)), _) => {
-                    return Ok(Integral(I32(::std::i32::MIN)))
-                },
-                (&LitKind::Int(I64_OVERFLOW, Unsuffixed), Some(&ty::TyInt(IntTy::I64))) |
-                (&LitKind::Int(I64_OVERFLOW, Signed(IntTy::I64)), _) => {
-                    return Ok(Integral(I64(::std::i64::MIN)))
-                },
-                (&LitKind::Int(n, Unsuffixed), Some(&ty::TyInt(IntTy::Is))) |
-                (&LitKind::Int(n, Signed(IntTy::Is)), _) => {
-                    match tcx.sess.target.int_type {
-                        IntTy::I32 => if n == I32_OVERFLOW {
-                            return Ok(Integral(Isize(Is32(::std::i32::MIN))));
-                        },
-                        IntTy::I64 => if n == I64_OVERFLOW {
-                            return Ok(Integral(Isize(Is64(::std::i64::MIN))));
-                        },
-                        _ => bug!(),
-                    }
-                },
-                _ => {},
-            }
+        match inner.node {
+            hir::ExprLit(ref lit) => {
+                use syntax::ast::*;
+                use syntax::ast::LitIntType::*;
+                const I8_OVERFLOW: u64 = ::std::i8::MAX as u64 + 1;
+                const I16_OVERFLOW: u64 = ::std::i16::MAX as u64 + 1;
+                const I32_OVERFLOW: u64 = ::std::i32::MAX as u64 + 1;
+                const I64_OVERFLOW: u64 = ::std::i64::MAX as u64 + 1;
+                match (&lit.node, ety.map(|t| &t.sty)) {
+                    (&LitKind::Int(I8_OVERFLOW, Unsuffixed), Some(&ty::TyInt(IntTy::I8))) |
+                    (&LitKind::Int(I8_OVERFLOW, Signed(IntTy::I8)), _) => {
+                        return Ok(Integral(I8(::std::i8::MIN)))
+                    },
+                    (&LitKind::Int(I16_OVERFLOW, Unsuffixed), Some(&ty::TyInt(IntTy::I16))) |
+                    (&LitKind::Int(I16_OVERFLOW, Signed(IntTy::I16)), _) => {
+                        return Ok(Integral(I16(::std::i16::MIN)))
+                    },
+                    (&LitKind::Int(I32_OVERFLOW, Unsuffixed), Some(&ty::TyInt(IntTy::I32))) |
+                    (&LitKind::Int(I32_OVERFLOW, Signed(IntTy::I32)), _) => {
+                        return Ok(Integral(I32(::std::i32::MIN)))
+                    },
+                    (&LitKind::Int(I64_OVERFLOW, Unsuffixed), Some(&ty::TyInt(IntTy::I64))) |
+                    (&LitKind::Int(I64_OVERFLOW, Signed(IntTy::I64)), _) => {
+                        return Ok(Integral(I64(::std::i64::MIN)))
+                    },
+                    (&LitKind::Int(n, Unsuffixed), Some(&ty::TyInt(IntTy::Is))) |
+                    (&LitKind::Int(n, Signed(IntTy::Is)), _) => {
+                        match tcx.sess.target.int_type {
+                            IntTy::I32 => if n == I32_OVERFLOW {
+                                return Ok(Integral(Isize(Is32(::std::i32::MIN))));
+                            },
+                            IntTy::I64 => if n == I64_OVERFLOW {
+                                return Ok(Integral(Isize(Is64(::std::i64::MIN))));
+                            },
+                            _ => bug!(),
+                        }
+                    },
+                    _ => {},
+                }
+            },
+            hir::ExprUnary(hir::UnNeg, ref inner) => {
+                // skip `--$expr`
+                return eval_const_expr_partial(tcx, inner, ty_hint, fn_args);
+            },
+            _ => {},
         }
         match eval_const_expr_partial(tcx, &inner, ty_hint, fn_args)? {
           Float(f) => Float(-f),

trunk/src/librustc_const_math/int.rs

@@ -503,7 +503,7 @@ impl ::std::ops::Shr<ConstInt> for ConstInt {
             I8(a) => Ok(I8(overflowing!(a.overflowing_shr(b), Op::Shr))),
             I16(a) => Ok(I16(overflowing!(a.overflowing_shr(b), Op::Shr))),
             I32(a) => Ok(I32(overflowing!(a.overflowing_shr(b), Op::Shr))),
-            I64(a) => Ok(I64(overflowing!(a.overflowing_shr(b), Op::Shl))),
+            I64(a) => Ok(I64(overflowing!(a.overflowing_shr(b), Op::Shr))),
             Isize(Is32(a)) => Ok(Isize(Is32(overflowing!(a.overflowing_shr(b), Op::Shr)))),
             Isize(Is64(a)) => Ok(Isize(Is64(overflowing!(a.overflowing_shr(b), Op::Shr)))),
             U8(a) => Ok(U8(overflowing!(a.overflowing_shr(b), Op::Shr))),

trunk/src/librustc_const_math/lib.rs

@@ -40,4 +40,4 @@ mod err;
 pub use int::*;
 pub use us::*;
 pub use is::*;
-pub use err::ConstMathErr;
+pub use err::{ConstMathErr, Op};

trunk/src/librustc_driver/driver.rs

@@ -528,19 +528,13 @@ pub fn phase_2_configure_and_expand(sess: &Session,
         middle::recursion_limit::update_recursion_limit(sess, &krate);
     });
 
-    time(time_passes, "gated macro checking", || {
-        sess.track_errors(|| {
-            let features =
-              syntax::feature_gate::check_crate_macros(sess.codemap(),
-                                                       &sess.parse_sess.span_diagnostic,
-                                                       &krate);
-
-            // these need to be set "early" so that expansion sees `quote` if enabled.
-            *sess.features.borrow_mut() = features;
-        })
+    // these need to be set "early" so that expansion sees `quote` if enabled.
+    sess.track_errors(|| {
+        *sess.features.borrow_mut() =
+            syntax::feature_gate::get_features(&sess.parse_sess.span_diagnostic,
+                                               &krate);
     })?;
 
-
     krate = time(time_passes, "crate injection", || {
         syntax::std_inject::maybe_inject_crates_ref(krate, sess.opts.alt_std_name.clone())
     });

trunk/src/librustc_mir/build/block.rs

@@ -44,11 +44,7 @@ impl<'a,'tcx> Builder<'a,'tcx> {
                     StmtKind::Expr { scope, expr } => {
                         unpack!(block = this.in_scope(scope, block, |this, _| {
                             let expr = this.hir.mirror(expr);
-                            let expr_span = expr.span;
-                            let temp = this.temp(expr.ty.clone());
-                            unpack!(block = this.into(&temp, block, expr));
-                            unpack!(block = this.build_drop(block, expr_span, temp));
-                            block.unit()
+                            this.stmt_expr(block, expr)
                         }));
                     }
                     StmtKind::Let { remainder_scope, init_scope, pattern, initializer } => {

trunk/src/librustc_mir/build/expr/as_rvalue.rs

@@ -189,6 +189,11 @@ impl<'a,'tcx> Builder<'a,'tcx> {
                 block.and(Rvalue::Aggregate(AggregateKind::Adt(adt_def, variant_index, substs),
                                             fields))
             }
+            ExprKind::Assign { .. } |
+            ExprKind::AssignOp { .. } => {
+                block = unpack!(this.stmt_expr(block, expr));
+                block.and(this.unit_rvalue())
+            }
             ExprKind::Literal { .. } |
             ExprKind::Block { .. } |
             ExprKind::Match { .. } |
@@ -201,8 +206,6 @@ impl<'a,'tcx> Builder<'a,'tcx> {
             ExprKind::Index { .. } |
             ExprKind::VarRef { .. } |
             ExprKind::SelfRef |
-            ExprKind::Assign { .. } |
-            ExprKind::AssignOp { .. } |
             ExprKind::Break { .. } |
             ExprKind::Continue { .. } |
             ExprKind::Return { .. } |

trunk/src/librustc_mir/build/expr/into.rs

@@ -12,12 +12,9 @@
 
 use build::{BlockAnd, BlockAndExtension, Builder};
 use build::expr::category::{Category, RvalueFunc};
-use build::scope::LoopScope;
 use hair::*;
-use rustc::middle::region::CodeExtent;
 use rustc::ty;
 use rustc::mir::repr::*;
-use syntax::codemap::Span;
 
 impl<'a,'tcx> Builder<'a,'tcx> {
     /// Compile `expr`, storing the result into `destination`, which
@@ -207,65 +204,6 @@ impl<'a,'tcx> Builder<'a,'tcx> {
                 }
                 exit_block.unit()
             }
-            ExprKind::Assign { lhs, rhs } => {
-                // Note: we evaluate assignments right-to-left. This
-                // is better for borrowck interaction with overloaded
-                // operators like x[j] = x[i].
-                let lhs = this.hir.mirror(lhs);
-                let lhs_span = lhs.span;
-                let rhs = unpack!(block = this.as_operand(block, rhs));
-                let lhs = unpack!(block = this.as_lvalue(block, lhs));
-                unpack!(block = this.build_drop(block, lhs_span, lhs.clone()));
-                this.cfg.push_assign(block, scope_id, expr_span, &lhs, Rvalue::Use(rhs));
-                block.unit()
-            }
-            ExprKind::AssignOp { op, lhs, rhs } => {
-                // FIXME(#28160) there is an interesting semantics
-                // question raised here -- should we "freeze" the
-                // value of the lhs here?  I'm inclined to think not,
-                // since it seems closer to the semantics of the
-                // overloaded version, which takes `&mut self`.  This
-                // only affects weird things like `x += {x += 1; x}`
-                // -- is that equal to `x + (x + 1)` or `2*(x+1)`?
-
-                // As above, RTL.
-                let rhs = unpack!(block = this.as_operand(block, rhs));
-                let lhs = unpack!(block = this.as_lvalue(block, lhs));
-
-                // we don't have to drop prior contents or anything
-                // because AssignOp is only legal for Copy types
-                // (overloaded ops should be desugared into a call).
-                this.cfg.push_assign(block, scope_id, expr_span, &lhs,
-                                     Rvalue::BinaryOp(op,
-                                                      Operand::Consume(lhs.clone()),
-                                                      rhs));
-
-                block.unit()
-            }
-            ExprKind::Continue { label } => {
-                this.break_or_continue(expr_span, label, block,
-                                       |loop_scope| loop_scope.continue_block)
-            }
-            ExprKind::Break { label } => {
-                this.break_or_continue(expr_span, label, block, |loop_scope| {
-                    loop_scope.might_break = true;
-                    loop_scope.break_block
-                })
-            }
-            ExprKind::Return { value } => {
-                block = match value {
-                    Some(value) => unpack!(this.into(&Lvalue::ReturnPointer, block, value)),
-                    None => {
-                        this.cfg.push_assign_unit(block, scope_id,
-                                                  expr_span, &Lvalue::ReturnPointer);
-                        block
-                    }
-                };
-                let extent = this.extent_of_return_scope();
-                let return_block = this.return_block();
-                this.exit_scope(expr_span, extent, block, return_block);
-                this.cfg.start_new_block().unit()
-            }
             ExprKind::Call { ty, fun, args } => {
                 let diverges = match ty.sty {
                     ty::TyFnDef(_, _, ref f) | ty::TyFnPtr(ref f) => {
@@ -294,6 +232,15 @@ impl<'a,'tcx> Builder<'a,'tcx> {
                 success.unit()
             }
 
+            // These cases don't actually need a destination
+            ExprKind::Assign { .. } |
+            ExprKind::AssignOp { .. } |
+            ExprKind::Continue { .. } |
+            ExprKind::Break { .. } |
+            ExprKind::Return {.. } => {
+                this.stmt_expr(block, expr)
+            }
+
             // these are the cases that are more naturally handled by some other mode
             ExprKind::Unary { .. } |
             ExprKind::Binary { .. } |
@@ -327,20 +274,4 @@ impl<'a,'tcx> Builder<'a,'tcx> {
             }
         }
     }
-
-    fn break_or_continue<F>(&mut self,
-                            span: Span,
-                            label: Option<CodeExtent>,
-                            block: BasicBlock,
-                            exit_selector: F)
-                            -> BlockAnd<()>
-        where F: FnOnce(&mut LoopScope) -> BasicBlock
-    {
-        let (exit_block, extent) = {
-            let loop_scope = self.find_loop_scope(span, label);
-            (exit_selector(loop_scope), loop_scope.extent)
-        };
-        self.exit_scope(span, extent, block, exit_block);
-        self.cfg.start_new_block().unit()
-    }
 }

trunk/src/librustc_mir/build/expr/mod.rs

@@ -77,3 +77,4 @@ mod as_operand;
 mod as_temp;
 mod category;
 mod into;
+mod stmt;