---

yaml
---
r: 210943
b: refs/heads/try
c: c69a152
h: refs/heads/master
i:
  210941: edabe39
  210939: ff73d16
  210935: 370f77e
  210927: 2538a77
  210911: 2d2bc3e
  210879: f0572be
  210815: a3bb327
  210687: 661f593
  210431: 1062752
  209919: b25de6b
  208895: b23d14d
v: v3

Author: Nick Hamann

[refs]

@@ -2,7 +2,7 @@
 refs/heads/master: 3e561f05c00cd180ec02db4ccab2840a4aba93d2
 refs/heads/snap-stage1: e33de59e47c5076a89eadeb38f4934f58a3618a6
 refs/heads/snap-stage3: ba0e1cd8147d452c356aacb29fb87568ca26f111
-refs/heads/try: 84b1e084862c08c19c36f0cf1f3698343c8ba7fa
+refs/heads/try: c69a152018de3c70e949f758d59e6aa86e19e9d4
 refs/tags/release-0.1: 1f5c5126e96c79d22cb7862f75304136e204f105
 refs/heads/dist-snap: ba4081a5a8573875fed17545846f6f6902c8ba8d
 refs/tags/release-0.2: c870d2dffb391e14efb05aa27898f1f6333a9596

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

@@ -54,9 +54,9 @@ The second is that the syntax is similar, but a bit different. I’ve added spac
 here to make them look a little closer:
 
 ```rust
-fn  plus_one_v1   (x: i32) -> i32 { x + 1 }
-let plus_one_v2 = |x: i32| -> i32 { x + 1 };
-let plus_one_v3 = |x: i32|          x + 1  ;
+fn  plus_one_v1   (x: i32 ) -> i32 { x + 1 }
+let plus_one_v2 = |x: i32 | -> i32 { x + 1 };
+let plus_one_v3 = |x: i32 |          x + 1  ;
 ```
 
 Small differences, but they’re similar in ways.
@@ -136,7 +136,7 @@ This gives us:
 note: `nums` moved into closure environment here because it has type
   `[closure(()) -> collections::vec::Vec<i32>]`, which is non-copyable
 let takes_nums = || nums;
-                 ^~~~~~~
+                    ^~~~~~~
 ```
 
 `Vec<T>` has ownership over its contents, and therefore, when we refer to it
@@ -352,8 +352,8 @@ error: the trait `core::marker::Sized` is not implemented for the type
 factory() -> (Fn(i32) -> Vec<i32>) {
              ^~~~~~~~~~~~~~~~~~~~~
 note: `core::ops::Fn(i32) -> collections::vec::Vec<i32>` does not have a constant size known at compile-time
-factory() -> (Fn(i32) -> Vec<i32>) {
-             ^~~~~~~~~~~~~~~~~~~~~
+fa ctory() -> (Fn(i32) -> Vec<i32>) {
+              ^~~~~~~~~~~~~~~~~~~~~
 
 ```
 

branches/try/src/doc/trpl/references-and-borrowing.md

@@ -297,7 +297,7 @@ We can’t modify `v` because it’s borrowed by the loop.
 References must live as long as the resource they refer to. Rust will check the
 scopes of your references to ensure that this is true.
 
-If Rust didn’t check this property, we could accidentally use a reference
+If Rust didn’t check that this property, we could accidentally use a reference
 which was invalid. For example:
 
 ```rust,ignore

branches/try/src/grammar/verify.rs

@@ -111,7 +111,7 @@ fn parse_token_list(file: &str) -> HashMap<String, token::Token> {
             "LIT_BINARY_RAW"    => token::Literal(token::BinaryRaw(Name(0), 0), None),
             "QUESTION"          => token::Question,
             "SHEBANG"           => token::Shebang(Name(0)),
-            _                   => continue,
+            _                   => panic!("Bad token str `{}`", val),
         };
 
         res.insert(num.to_string(), tok);

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

@@ -1,4 +1,4 @@
-// Copyright 2012-2015 The Rust Project Developers. See the COPYRIGHT
+// Copyright 2012-2014 The Rust Project Developers. See the COPYRIGHT
 // file at the top-level directory of this distribution and at
 // http://rust-lang.org/COPYRIGHT.
 //
@@ -34,7 +34,7 @@ use std::borrow::{Cow, IntoCow};
 use std::num::wrapping::OverflowingOps;
 use std::cmp::Ordering;
 use std::collections::hash_map::Entry::Vacant;
-use std::{i8, i16, i32, i64, u8, u16, u32, u64};
+use std::{i8, i16, i32, i64};
 use std::rc::Rc;
 
 fn lookup_const<'a>(tcx: &'a ty::ctxt, e: &Expr) -> Option<&'a Expr> {
@@ -461,16 +461,6 @@ pub fn const_uint_checked_neg<'a>(
     Ok(const_uint((!a).wrapping_add(1)))
 }
 
-fn const_uint_not(a: u64, opt_ety: Option<UintTy>) -> const_val {
-    let mask = match opt_ety {
-        Some(UintTy::U8) => u8::MAX as u64,
-        Some(UintTy::U16) => u16::MAX as u64,
-        Some(UintTy::U32) => u32::MAX as u64,
-        None | Some(UintTy::U64) => u64::MAX,
-    };
-    const_uint(!a & mask)
-}
-
 macro_rules! overflow_checking_body {
     ($a:ident, $b:ident, $ety:ident, $overflowing_op:ident,
      lhs: $to_8_lhs:ident $to_16_lhs:ident $to_32_lhs:ident,
@@ -687,7 +677,7 @@ pub fn eval_const_expr_partial<'tcx>(tcx: &ty::ctxt<'tcx>,
       ast::ExprUnary(ast::UnNot, ref inner) => {
         match try!(eval_const_expr_partial(tcx, &**inner, ety)) {
           const_int(i) => const_int(!i),
-          const_uint(i) => const_uint_not(i, expr_uint_type),
+          const_uint(i) => const_uint(!i),
           const_bool(b) => const_bool(!b),
           const_str(_) => signal!(e, NotOnString),
           const_float(_) => signal!(e, NotOnFloat),

branches/try/src/librustc_typeck/check/mod.rs

@@ -3153,10 +3153,26 @@ fn check_expr_with_unifier<'a, 'tcx, F>(fcx: &FnCtxt<'a, 'tcx>,
                                                            Some(&**oprnd), oprnd_t, lvalue_pref) {
                             Some(mt) => mt.ty,
                             None => {
-                                fcx.type_error_message(expr.span, |actual| {
-                                    format!("type `{}` cannot be \
-                                            dereferenced", actual)
-                                }, oprnd_t, None);
+                                let is_newtype = match oprnd_t.sty {
+                                    ty::ty_struct(did, substs) => {
+                                        let fields = ty::struct_fields(fcx.tcx(), did, substs);
+                                        fields.len() == 1
+                                        && fields[0].name ==
+                                        token::special_idents::unnamed_field.name
+                                    }
+                                    _ => false
+                                };
+                                if is_newtype {
+                                    // This is an obsolete struct deref
+                                    span_err!(tcx.sess, expr.span, E0068,
+                                        "single-field tuple-structs can \
+                                         no longer be dereferenced");
+                                } else {
+                                    fcx.type_error_message(expr.span, |actual| {
+                                        format!("type `{}` cannot be \
+                                                dereferenced", actual)
+                                    }, oprnd_t, None);
+                                }
                                 tcx.types.err
                             }
                         }

branches/try/src/librustc_typeck/diagnostics.rs

@@ -170,6 +170,63 @@ Since `return;` is just like `return ();`, there is a mismatch between the
 function's return type and the value being returned.
 "##,
 
+E0072: r##"
+When defining a recursive struct or enum, any use of the type being defined
+from inside the definition must occur behind a pointer (like `Box` or `&`).
+This is because structs and enums must have a well-defined size, and without
+the pointer the size of the type would need to be unbounded.
+
+Consider the following erroneous definition of a type for a list of bytes:
+
+```
+// error, illegal recursive struct type
+struct ListNode {
+    head: u8,
+    tail: Option<ListNode>,
+}
+```
+
+This type cannot have a well-defined size, because it needs to be arbitrarily
+large (since we would be able to nest `ListNode`s to any depth). Specifically,
+
+```
+size of ListNode = 1 byte for head
+                 + 1 byte for the discriminant of the Option
+                 + size of ListNode
+```
+
+One way to fix this is by wrapping `ListNode` in a `Box`, like so:
+
+```
+struct ListNode {
+    head: u8,
+    tail: Option<Box<ListNode>>,
+}
+```
+
+This works because `Box` is a pointer, so its size is well-known.
+"##,
+
+E0073: r##"
+You cannot define a struct (or enum) `Foo` that requires an instance of `Foo`
+in order to make a new `Foo` value. This is because there would be no way a
+first instance of `Foo` could be made to initialize another instance!
+
+Here's an example of a struct that has this problem:
+
+```
+struct Foo { x: Box<Foo> } // error
+```
+
+One fix is to use `Option`, like so:
+
+```
+struct Foo { x: Option<Box<Foo>> }
+```
+
+Now it's possible to create at least one instance of `Foo`: `Foo { x: None }`.
+"##,
+
 E0081: r##"
 Enum discriminants are used to differentiate enum variants stored in memory.
 This error indicates that the same value was used for two or more variants,
@@ -327,6 +384,19 @@ RFC. It is, however, [currently unimplemented][iss15872].
 [iss15872]: https://github.com/rust-lang/rust/issues/15872
 "##,
 
+E0121: r##"
+In order to be consistent with Rust's lack of global type inference, type
+placeholders are disallowed by design in item signatures.
+
+Examples of this error include:
+
+```
+fn foo() -> _ { 5 } // error, explicitly write out the return type instead
+
+static BAR: _ = "test"; // error, explicitly write out the type instead
+```
+"##,
+
 E0131: r##"
 It is not possible to define `main` with type parameters, or even with function
 parameters. When `main` is present, it must take no arguments and return `()`.
@@ -355,6 +425,28 @@ return, for example with a `loop` that never breaks or a call to another
 diverging function (such as `panic!()`).
 "##,
 
+E0178: r##"
+In types, the `+` type operator has low precedence, so it is often necessary
+to use parentheses.
+
+For example:
+
+```
+trait Foo {}
+
+struct Bar<'a> {
+    w: &'a Foo + Copy,   // error, use &'a (Foo + Copy)
+    x: &'a Foo + 'a,     // error, use &'a (Foo + 'a)
+    y: &'a mut Foo + 'a, // error, use &'a mut (Foo + 'a)
+    z: fn() -> Foo + 'a, // error, use fn() -> (Foo + 'a)
+}
+```
+
+More details can be found in [RFC 438].
+
+[RFC 438]: https://github.com/rust-lang/rfcs/pull/438
+"##,
+
 E0184: r##"
 Explicitly implementing both Drop and Copy for a type is currently disallowed.
 This feature can make some sense in theory, but the current implementation is
@@ -632,6 +724,35 @@ traits, so it is not possible to overload them. See [RFC 953] for a proposal
 to change this.
 
 [RFC 953]: https://github.com/rust-lang/rfcs/pull/953
+"##,
+
+E0371: r##"
+When `Trait2` is a subtrait of `Trait1` (for example, when `Trait2` has a
+definition like `trait Trait2: Trait1 { ... }`), it is not allowed to implement
+`Trait1` for `Trait2`. This is because `Trait2` already implements `Trait1` by
+definition, so it is not useful to do this.
+
+Example:
+
+```
+trait Foo { fn foo(&self) { } }
+trait Bar: Foo { }
+trait Baz: Bar { }
+
+impl Bar for Baz { } // error, `Baz` implements `Bar` by definition
+impl Foo for Baz { } // error, `Baz` implements `Bar` which implements `Foo`
+impl Baz for Baz { } // error, `Baz` (trivially) implements `Baz`
+impl Baz for Bar { } // Note: This is OK
+```
+"##,
+
+E0372: r##"
+Trying to implement a trait for a trait object (as in `impl Trait1 for
+Trait2 { ... }`) does not work if the trait is not object-safe. Please see the
+[RFC 255] for more details on object safety rules.
+
+[RFC 255]:https://github.com/rust-lang/rfcs/blob/master/text/0255-object-\
+safety.md
 "##
 
 }
@@ -660,8 +781,6 @@ register_diagnostics! {
     E0068,
     E0070,
     E0071,
-    E0072,
-    E0073,
     E0074,
     E0075,
     E0076,
@@ -685,7 +804,6 @@ register_diagnostics! {
     E0118,
     E0119,
     E0120,
-    E0121,
     E0122,
     E0123,
     E0124,
@@ -702,7 +820,6 @@ register_diagnostics! {
     E0172,
     E0173, // manual implementations of unboxed closure traits are experimental
     E0174, // explicit use of unboxed closure methods are experimental
-    E0178,
     E0182,
     E0183,
     E0185,
@@ -774,8 +891,6 @@ register_diagnostics! {
     E0366, // dropck forbid specialization to concrete type or region
     E0367, // dropck forbid specialization to predicate not in struct/enum
     E0369, // binary operation `<op>` cannot be applied to types
-    E0371, // impl Trait for Trait is illegal
-    E0372, // impl Trait for Trait where Trait is not object safe
     E0374, // the trait `CoerceUnsized` may only be implemented for a coercion
            // between structures with one field being coerced, none found
     E0375, // the trait `CoerceUnsized` may only be implemented for a coercion

branches/try/src/libsyntax/feature_gate.rs

@@ -258,6 +258,7 @@ pub const KNOWN_ATTRIBUTES: &'static [(&'static str, AttributeType)] = &[
     ("no_builtins", Whitelisted),
     ("no_mangle", Whitelisted),
     ("no_stack_check", Whitelisted),
+    ("packed", Whitelisted),
     ("static_assert", Gated("static_assert",
                             "`#[static_assert]` is an experimental feature, and has a poor API")),
     ("no_debug", Whitelisted),

branches/try/src/test/compile-fail/coherence-impl-trait-for-trait.rs

@@ -15,14 +15,14 @@ trait Foo { fn dummy(&self) { } }
 trait Bar: Foo { }
 trait Baz: Bar { }
 
-// Subtraits of Baz are not legal:
+// Supertraits of Baz are not legal:
 impl Foo for Baz { }   //~ ERROR E0371
 impl Bar for Baz { }   //~ ERROR E0371
 impl Baz for Baz { }   //~ ERROR E0371
 
 // But other random traits are:
 trait Other { }
-impl Other for Baz { } // OK, Bar not a subtrait of Baz
+impl Other for Baz { } // OK, Other not a supertrait of Baz
 
 // If the trait is not object-safe, we give a more tailored message
 // because we're such schnuckels: