Auto merge of #33376 - Manishearth:rollup, r=Manishearth

Rollup of 14 pull requests

- Successful merges: #33277, #33294, #33314, #33322, #33333, #33338, #33339, #33340, #33343, #33357, #33363, #33365, #33371, #33372
- Failed merges:

Author: bors

src/doc/book/getting-started.md

@@ -8,7 +8,7 @@ we’ll talk about Cargo, Rust’s build system and package manager.
 
 The first step to using Rust is to install it. Generally speaking, you’ll need
 an Internet connection to run the commands in this section, as we’ll be
-downloading Rust from the internet.
+downloading Rust from the Internet.
 
 We’ll be showing off a number of commands using a terminal, and those lines all
 start with `$`. We don't need to type in the `$`s, they are there to indicate
@@ -399,13 +399,13 @@ Let’s convert the Hello World program to Cargo. To Cargo-fy a project, you nee
 to do three things:
 
 1. Put your source file in the right directory.
-2. Get rid of the old executable (`main.exe` on Windows, `main` everywhere else)
-   and make a new one.
+2. Get rid of the old executable (`main.exe` on Windows, `main` everywhere
+   else).
 3. Make a Cargo configuration file.
 
 Let's get started!
 
-### Creating a new Executable and Source Directory
+### Creating a Source Directory and Removing the Old Executable
 
 First, go back to your terminal, move to your *hello_world* directory, and
 enter the following commands:

src/libcollections/fmt.rs

@@ -333,7 +333,7 @@
 //! precision := count | '*'
 //! type := identifier | ''
 //! count := parameter | integer
-//! parameter := integer '$'
+//! parameter := argument '$'
 //! ```
 //!
 //! # Formatting Parameters
@@ -403,11 +403,12 @@
 //! println!("Hello {:5}!", "x");
 //! println!("Hello {:1$}!", "x", 5);
 //! println!("Hello {1:0$}!", 5, "x");
+//! println!("Hello {:width$}!", "x", width = 5);
 //! ```
 //!
 //! Referring to an argument with the dollar syntax does not affect the "next
-//! argument" counter, so it's usually a good idea to refer to all arguments by
-//! their position explicitly.
+//! argument" counter, so it's usually a good idea to refer to arguments by
+//! position, or use named arguments.
 //!
 //! ## Precision
 //!
@@ -426,7 +427,7 @@
 //!
 //!    the integer `N` itself is the precision.
 //!
-//! 2. An integer followed by dollar sign `.N$`:
+//! 2. An integer or name followed by dollar sign `.N$`:
 //!
 //!    use format *argument* `N` (which must be a `usize`) as the precision.
 //!
@@ -456,6 +457,10 @@
 //! // Hello {next arg (x)} is {arg 2 (0.01) with precision
 //! //                          specified in its predecessor (5)}
 //! println!("Hello {} is {2:.*}",   "x", 5, 0.01);
+//!
+//! // Hello {next arg (x)} is {arg "number" (0.01) with precision specified
+//! //                          in arg "prec" (5)}
+//! println!("Hello {} is {number:.prec$}", "x", prec = 5, number = 0.01);
 //! ```
 //!
 //! All print the same thing:

src/libcore/mem.rs

@@ -110,6 +110,7 @@ pub use intrinsics::transmute;
 ///     }
 /// }
 /// ```
+#[inline]
 #[stable(feature = "rust1", since = "1.0.0")]
 pub fn forget<T>(t: T) {
     unsafe { intrinsics::forget(t) }

src/librustc_borrowck/diagnostics.rs

@@ -314,6 +314,82 @@ let c = &i; // still ok!
 ```
 "##,
 
+E0501: r##"
+This error indicates that a mutable variable is being used while it is still
+captured by a closure. Because the closure has borrowed the variable, it is not
+available for use until the closure goes out of scope.
+
+Note that a capture will either move or borrow a variable, but in this
+situation, the closure is borrowing the variable. Take a look at
+http://rustbyexample.com/fn/closures/capture.html for more information about
+capturing.
+
+Example of erroneous code:
+
+```compile_fail
+fn inside_closure(x: &mut i32) {
+    // Actions which require unique access
+}
+
+fn outside_closure(x: &mut i32) {
+    // Actions which require unique access
+}
+
+fn foo(a: &mut i32) {
+    let bar = || {
+        inside_closure(a)
+    };
+    outside_closure(a); // error: cannot borrow `*a` as mutable because previous
+                        //        closure requires unique access.
+}
+```
+
+To fix this error, you can place the closure in its own scope:
+
+```
+fn inside_closure(x: &mut i32) {}
+fn outside_closure(x: &mut i32) {}
+
+fn foo(a: &mut i32) {
+    {
+        let bar = || {
+            inside_closure(a)
+        };
+    } // borrow on `a` ends.
+    outside_closure(a); // ok!
+}
+```
+
+Or you can pass the variable as a parameter to the closure:
+
+```
+fn inside_closure(x: &mut i32) {}
+fn outside_closure(x: &mut i32) {}
+
+fn foo(a: &mut i32) {
+    let bar = |s: &mut i32| {
+        inside_closure(s)
+    };
+    outside_closure(a);
+    bar(a);
+}
+```
+
+It may be possible to define the closure later:
+
+```
+fn inside_closure(x: &mut i32) {}
+fn outside_closure(x: &mut i32) {}
+
+fn foo(a: &mut i32) {
+    outside_closure(a);
+    let bar = || {
+        inside_closure(a)
+    };
+}
+```
+"##,
+
 E0507: r##"
 You tried to move out of a value which was borrowed. Erroneous code example:
 
@@ -436,7 +512,6 @@ register_diagnostics! {
     E0388, // {} in a static location
     E0389, // {} in a `&` reference
     E0500, // closure requires unique access to `..` but .. is already borrowed
-    E0501, // cannot borrow `..`.. as .. because previous closure requires unique access
     E0502, // cannot borrow `..`.. as .. because .. is also borrowed as ...
     E0503, // cannot use `..` because it was mutably borrowed
     E0504, // cannot move `..` into closure because it is borrowed

src/librustc_const_eval/eval.rs

@@ -377,13 +377,6 @@ pub enum ErrKind {
     NotOn(ConstVal),
     CallOn(ConstVal),
 
-    NegateWithOverflow(i64),
-    AddiWithOverflow(i64, i64),
-    SubiWithOverflow(i64, i64),
-    MuliWithOverflow(i64, i64),
-    AdduWithOverflow(u64, u64),
-    SubuWithOverflow(u64, u64),
-    MuluWithOverflow(u64, u64),
     DivideByZero,
     DivideWithOverflow,
     ModuloByZero,
@@ -415,6 +408,7 @@ pub enum ErrKind {
     TypeMismatch(String, ConstInt),
     BadType(ConstVal),
     ErroneousReferencedConstant(Box<ConstEvalErr>),
+    CharCast(ConstInt),
 }
 
 impl From<ConstMathErr> for ErrKind {
@@ -439,13 +433,6 @@ impl ConstEvalErr {
             NotOn(ref const_val) => format!("not on {}", const_val.description()).into_cow(),
             CallOn(ref const_val) => format!("call on {}", const_val.description()).into_cow(),
 
-            NegateWithOverflow(..) => "attempted to negate with overflow".into_cow(),
-            AddiWithOverflow(..) => "attempted to add with overflow".into_cow(),
-            SubiWithOverflow(..) => "attempted to sub with overflow".into_cow(),
-            MuliWithOverflow(..) => "attempted to mul with overflow".into_cow(),
-            AdduWithOverflow(..) => "attempted to add with overflow".into_cow(),
-            SubuWithOverflow(..) => "attempted to sub with overflow".into_cow(),
-            MuluWithOverflow(..) => "attempted to mul with overflow".into_cow(),
             DivideByZero         => "attempted to divide by zero".into_cow(),
             DivideWithOverflow   => "attempted to divide with overflow".into_cow(),
             ModuloByZero         => "attempted remainder with a divisor of zero".into_cow(),
@@ -482,6 +469,9 @@ impl ConstEvalErr {
             },
             BadType(ref i) => format!("value of wrong type: {:?}", i).into_cow(),
             ErroneousReferencedConstant(_) => "could not evaluate referenced constant".into_cow(),
+            CharCast(ref got) => {
+                format!("only `u8` can be cast as `char`, not `{}`", got.description()).into_cow()
+            },
         }
     }
 }
@@ -824,7 +814,10 @@ pub fn eval_const_expr_partial<'tcx>(tcx: &TyCtxt<'tcx>,
           debug!("const call({:?})", call_args);
           eval_const_expr_partial(tcx, &result, ty_hint, Some(&call_args))?
       },
-      hir::ExprLit(ref lit) => lit_to_const(&lit.node, tcx, ety, lit.span)?,
+      hir::ExprLit(ref lit) => match lit_to_const(&lit.node, tcx, ety, lit.span) {
+          Ok(val) => val,
+          Err(err) => signal!(e, err),
+      },
       hir::ExprBlock(ref block) => {
         match block.expr {
             Some(ref expr) => eval_const_expr_partial(tcx, &expr, ty_hint, fn_args)?,
@@ -930,7 +923,10 @@ pub fn eval_const_expr_partial<'tcx>(tcx: &TyCtxt<'tcx>,
     };
 
     match (ety.map(|t| &t.sty), result) {
-        (Some(ref ty_hint), Integral(i)) => Ok(Integral(infer(i, tcx, ty_hint, e.span)?)),
+        (Some(ref ty_hint), Integral(i)) => match infer(i, tcx, ty_hint) {
+            Ok(inferred) => Ok(Integral(inferred)),
+            Err(err) => signal!(e, err),
+        },
         (_, result) => Ok(result),
     }
 }
@@ -939,15 +935,9 @@ fn infer<'tcx>(
     i: ConstInt,
     tcx: &TyCtxt<'tcx>,
     ty_hint: &ty::TypeVariants<'tcx>,
-    span: Span
-) -> Result<ConstInt, ConstEvalErr> {
+) -> Result<ConstInt, ErrKind> {
     use syntax::ast::*;
 
-    let err = |e| ConstEvalErr {
-        span: span,
-        kind: e,
-    };
-
     match (ty_hint, i) {
         (&ty::TyInt(IntTy::I8), result @ I8(_)) => Ok(result),
         (&ty::TyInt(IntTy::I16), result @ I16(_)) => Ok(result),
@@ -993,17 +983,17 @@ fn infer<'tcx>(
                 Err(_) => Ok(Usize(ConstUsize::Us32(i as u32))),
             }
         },
-        (&ty::TyUint(_), InferSigned(_)) => Err(err(IntermediateUnsignedNegative)),
+        (&ty::TyUint(_), InferSigned(_)) => Err(IntermediateUnsignedNegative),
 
-        (&ty::TyInt(ity), i) => Err(err(TypeMismatch(ity.to_string(), i))),
-        (&ty::TyUint(ity), i) => Err(err(TypeMismatch(ity.to_string(), i))),
+        (&ty::TyInt(ity), i) => Err(TypeMismatch(ity.to_string(), i)),
+        (&ty::TyUint(ity), i) => Err(TypeMismatch(ity.to_string(), i)),
 
         (&ty::TyEnum(ref adt, _), i) => {
             let hints = tcx.lookup_repr_hints(adt.did);
             let int_ty = tcx.enum_repr_type(hints.iter().next());
-            infer(i, tcx, &int_ty.to_ty(tcx).sty, span)
+            infer(i, tcx, &int_ty.to_ty(tcx).sty)
         },
-        (_, i) => Err(err(BadType(ConstVal::Integral(i)))),
+        (_, i) => Err(BadType(ConstVal::Integral(i))),
     }
 }
 
@@ -1089,23 +1079,22 @@ fn cast_const_int<'tcx>(tcx: &TyCtxt<'tcx>, val: ConstInt, ty: ty::Ty) -> CastRe
                 Err(_) => Ok(Integral(Usize(ConstUsize::Us32(v as u32)))),
             }
         },
-        ty::TyFloat(ast::FloatTy::F64) if val.is_negative() => {
-            // FIXME: this could probably be prettier
-            // there's no easy way to turn an `Infer` into a f64
-            let val = (-val).map_err(Math)?;
-            let val = val.to_u64().unwrap() as f64;
-            let val = -val;
-            Ok(Float(val))
+        ty::TyFloat(ast::FloatTy::F64) => match val.erase_type() {
+            Infer(u) => Ok(Float(u as f64)),
+            InferSigned(i) => Ok(Float(i as f64)),
+            _ => bug!("ConstInt::erase_type returned something other than Infer/InferSigned"),
         },
-        ty::TyFloat(ast::FloatTy::F64) => Ok(Float(val.to_u64().unwrap() as f64)),
-        ty::TyFloat(ast::FloatTy::F32) if val.is_negative() => {
-            let val = (-val).map_err(Math)?;
-            let val = val.to_u64().unwrap() as f32;
-            let val = -val;
-            Ok(Float(val as f64))
+        ty::TyFloat(ast::FloatTy::F32) => match val.erase_type() {
+            Infer(u) => Ok(Float(u as f32 as f64)),
+            InferSigned(i) => Ok(Float(i as f32 as f64)),
+            _ => bug!("ConstInt::erase_type returned something other than Infer/InferSigned"),
         },
-        ty::TyFloat(ast::FloatTy::F32) => Ok(Float(val.to_u64().unwrap() as f32 as f64)),
         ty::TyRawPtr(_) => Err(ErrKind::UnimplementedConstVal("casting an address to a raw ptr")),
+        ty::TyChar => match infer(val, tcx, &ty::TyUint(ast::UintTy::U8)) {
+            Ok(U8(u)) => Ok(Char(u as char)),
+            // can only occur before typeck, typeck blocks `T as char` for `T` != `u8`
+            _ => Err(CharCast(val)),
+        },
         _ => Err(CannotCast),
     }
 }
@@ -1136,36 +1125,36 @@ fn lit_to_const<'tcx>(lit: &ast::LitKind,
                       tcx: &TyCtxt<'tcx>,
                       ty_hint: Option<Ty<'tcx>>,
                       span: Span,
-                      ) -> Result<ConstVal, ConstEvalErr> {
+                      ) -> Result<ConstVal, ErrKind> {
     use syntax::ast::*;
     use syntax::ast::LitIntType::*;
     match *lit {
         LitKind::Str(ref s, _) => Ok(Str((*s).clone())),
         LitKind::ByteStr(ref data) => Ok(ByteStr(data.clone())),
         LitKind::Byte(n) => Ok(Integral(U8(n))),
         LitKind::Int(n, Signed(ity)) => {
-            infer(InferSigned(n as i64), tcx, &ty::TyInt(ity), span).map(Integral)
+            infer(InferSigned(n as i64), tcx, &ty::TyInt(ity)).map(Integral)
         },
 
         LitKind::Int(n, Unsuffixed) => {
             match ty_hint.map(|t| &t.sty) {
                 Some(&ty::TyInt(ity)) => {
-                    infer(InferSigned(n as i64), tcx, &ty::TyInt(ity), span).map(Integral)
+                    infer(InferSigned(n as i64), tcx, &ty::TyInt(ity)).map(Integral)
                 },
                 Some(&ty::TyUint(uty)) => {
-                    infer(Infer(n), tcx, &ty::TyUint(uty), span).map(Integral)
+                    infer(Infer(n), tcx, &ty::TyUint(uty)).map(Integral)
                 },
                 None => Ok(Integral(Infer(n))),
                 Some(&ty::TyEnum(ref adt, _)) => {
                     let hints = tcx.lookup_repr_hints(adt.did);
                     let int_ty = tcx.enum_repr_type(hints.iter().next());
-                    infer(Infer(n), tcx, &int_ty.to_ty(tcx).sty, span).map(Integral)
+                    infer(Infer(n), tcx, &int_ty.to_ty(tcx).sty).map(Integral)
                 },
                 Some(ty_hint) => bug!("bad ty_hint: {:?}, {:?}", ty_hint, lit),
             }
         },
         LitKind::Int(n, Unsigned(ity)) => {
-            infer(Infer(n), tcx, &ty::TyUint(ity), span).map(Integral)
+            infer(Infer(n), tcx, &ty::TyUint(ity)).map(Integral)
         },
 
         LitKind::Float(ref n, _) |