Rollup of 7 pull requests

src/doc/reference.md

@@ -3529,7 +3529,9 @@ The actual implementation for each vtable entry can vary on an object-by-object
 basis.
 
 Note that for a trait object to be instantiated, the trait must be
-_object-safe_. Object safety rules are defined in [RFC 255][rfc255].
+_object-safe_. Object safety rules are defined in [RFC 255].
+
+[RFC 255]: https://github.com/rust-lang/rfcs/blob/master/text/0255-object-safety.md
 
 Given a pointer-typed expression `E` of type `&T` or `Box<T>`, where `T`
 implements trait `R`, casting `E` to the corresponding pointer type `&R` or

src/doc/trpl/iterators.md

@@ -42,7 +42,7 @@ loop is just a handy way to write this `loop`/`match`/`break` construct.
 `for` loops aren't the only thing that uses iterators, however. Writing your
 own iterator involves implementing the `Iterator` trait. While doing that is
 outside of the scope of this guide, Rust provides a number of useful iterators
-to accomplish various threads. Before we talk about those, we should talk about a
+to accomplish various tasks. Before we talk about those, we should talk about a
 Rust anti-pattern. And that's using ranges like this.
 
 Yes, we just talked about how ranges are cool. But ranges are also very

src/doc/trpl/the-stack-and-the-heap.md

@@ -80,15 +80,15 @@ This memory is kind of like a giant array: addresses start at zero and go
 up to the final number. So here’s a diagram of our first stack frame:
 
 | Address | Name | Value |
-+---------+------+-------+
+|---------|------|-------|
 | 0       | x    | 42    |
 
 We’ve got `x` located at address `0`, with the value `42`.
 
 When `foo()` is called, a new stack frame is allocated:
 
 | Address | Name | Value |
-+---------+------+-------+
+|---------|------|-------|
 | 2       | z    | 100   |
 | 1       | y    | 5     |
 | 0       | x    | 42    |
@@ -107,7 +107,7 @@ value being stored.
 After `foo()` is over, its frame is deallocated:
 
 | Address | Name | Value |
-+---------+------+-------+
+|---------|------|-------|
 | 0       | x    | 42    |
 
 And then, after `main()`, even this last value goes away. Easy!
@@ -142,13 +142,13 @@ fn main() {
 Okay, first, we call `main()`:
 
 | Address | Name | Value |
-+---------+------+-------+
+|---------|------|-------|
 | 0       | x    | 42    |
 
 Next up, `main()` calls `foo()`:
 
 | Address | Name | Value |
-+---------+------+-------+
+|---------|------|-------|
 | 3       | c    | 1     |
 | 2       | b    | 100   |
 | 1       | a    | 5     |
@@ -157,7 +157,7 @@ Next up, `main()` calls `foo()`:
 And then `foo()` calls `bar()`:
 
 | Address | Name | Value |
-+---------+------+-------+
+|---------|------|-------|
 | 4       | i    | 6     |
 | 3       | c    | 1     |
 | 2       | b    | 100   |
@@ -170,7 +170,7 @@ After `bar()` is over, its frame is deallocated, leaving just `foo()` and
 `main()`:
 
 | Address | Name | Value |
-+---------+------+-------+
+|---------|------|-------|
 | 3       | c    | 1     |
 | 2       | b    | 100   |
 | 1       | a    | 5     |
@@ -179,7 +179,7 @@ After `bar()` is over, its frame is deallocated, leaving just `foo()` and
 And then `foo()` ends, leaving just `main()`
 
 | Address | Name | Value |
-+---------+------+-------+
+|---------|------|-------|
 | 0       | x    | 42    |
 
 And then we’re done. Getting the hang of it? It’s like piling up dishes: you
@@ -206,7 +206,7 @@ fn main() {
 Here’s what happens in memory when `main()` is called:
 
 | Address | Name | Value  |
-+---------+------+--------+
+|---------|------|--------|
 | 1       | y    | 42     |
 | 0       | x    | ?????? |
 
@@ -218,7 +218,7 @@ it allocates some memory for the heap, and puts `5` there. The memory now looks
 like this:
 
 | Address         | Name | Value          |
-+-----------------+------+----------------+
+|-----------------|------|----------------|
 | 2<sup>30</sup>  |      | 5              |
 | ...             | ...  | ...            |
 | 1               | y    | 42             |
@@ -243,7 +243,7 @@ layout of a program which has been running for a while now:
 
 
 | Address              | Name | Value                |
-+----------------------+------+----------------------+
+|----------------------|------|----------------------|
 | 2<sup>30</sup>       |      | 5                    |
 | (2<sup>30</sup>) - 1 |      |                      |
 | (2<sup>30</sup>) - 2 |      |                      |
@@ -272,7 +272,7 @@ when it was created. Great! So when `x` goes away, it first frees the memory
 allocated on the heap:
 
 | Address | Name | Value  |
-+---------+------+--------+
+|---------|------|--------|
 | 1       | y    | 42     |
 | 0       | x    | ?????? |
 
@@ -305,7 +305,7 @@ fn main() {
 When we enter `main()`, memory looks like this:
 
 | Address | Name | Value |
-+---------+------+-------+
+|---------|------|-------|
 | 1       | y    | 0     |
 | 0       | x    | 5     |
 
@@ -315,7 +315,7 @@ memory location that `x` lives at, which in this case is `0`.
 What about when we call `foo()`, passing `y` as an argument?
 
 | Address | Name | Value |
-+---------+------+-------+
+|---------|------|-------|
 | 3       | z    | 42    |
 | 2       | i    | 0     |
 | 1       | y    | 0     |
@@ -367,7 +367,7 @@ fn main() {
 First, we call `main()`:
 
 | Address         | Name | Value          |
-+-----------------+------+----------------+
+|-----------------|------|----------------|
 | 2<sup>30</sup>  |      | 20             |
 | ...             | ...  | ...            |
 | 2               | j    | 0              |
@@ -380,7 +380,7 @@ value pointing there.
 Next, at the end of `main()`, `foo()` gets called:
 
 | Address         | Name | Value          |
-+-----------------+------+----------------+
+|-----------------|------|----------------|
 | 2<sup>30</sup>  |      | 20             |
 | ...             | ...  | ...            |
 | 5               | z    | 4              |
@@ -397,7 +397,7 @@ since `j` points at `h`.
 Next, `foo()` calls `baz()`, passing `z`:
 
 | Address         | Name | Value          |
-+-----------------+------+----------------+
+|-----------------|------|----------------|
 | 2<sup>30</sup>  |      | 20             |
 | ...             | ...  | ...            |
 | 7               | g    | 100            |
@@ -413,7 +413,7 @@ We’ve allocated memory for `f` and `g`. `baz()` is very short, so when it’s
 over, we get rid of its stack frame:
 
 | Address         | Name | Value          |
-+-----------------+------+----------------+
+|-----------------|------|----------------|
 | 2<sup>30</sup>  |      | 20             |
 | ...             | ...  | ...            |
 | 5               | z    | 4              |
@@ -426,7 +426,7 @@ over, we get rid of its stack frame:
 Next, `foo()` calls `bar()` with `x` and `z`:
 
 | Address              | Name | Value                |
-+----------------------+------+----------------------+
+|----------------------|------|----------------------|
 |  2<sup>30</sup>      |      | 20                   |
 | (2<sup>30</sup>) - 1 |      | 5                    |
 | ...                  | ...  | ...                  |
@@ -449,7 +449,7 @@ case, we set up the variables as usual.
 At the end of `bar()`, it calls `baz()`:
 
 | Address              | Name | Value                |
-+----------------------+------+----------------------+
+|----------------------|------|----------------------|
 |  2<sup>30</sup>      |      | 20                   |
 | (2<sup>30</sup>) - 1 |      | 5                    |
 | ...                  | ...  | ...                  |
@@ -473,7 +473,7 @@ far.
 After `baz()` is over, we get rid of `f` and `g`:
 
 | Address              | Name | Value                |
-+----------------------+------+----------------------+
+|----------------------|------|----------------------|
 |  2<sup>30</sup>      |      | 20                   |
 | (2<sup>30</sup>) - 1 |      | 5                    |
 | ...                  | ...  | ...                  |
@@ -493,7 +493,7 @@ Next, we return from `bar()`. `d` in this case is a `Box<T>`, so it also frees
 what it points to: (2<sup>30</sup>) - 1.
 
 | Address         | Name | Value          |
-+-----------------+------+----------------+
+|-----------------|------|----------------|
 |  2<sup>30</sup> |      | 20             |
 | ...             | ...  | ...            |
 | 5               | z    | 4              |
@@ -506,7 +506,7 @@ what it points to: (2<sup>30</sup>) - 1.
 And after that, `foo()` returns:
 
 | Address         | Name | Value          |
-+-----------------+------+----------------+
+|-----------------|------|----------------|
 |  2<sup>30</sup> |      | 20             |
 | ...             | ...  | ...            |
 | 2               | j    | 0              |

src/librustc_resolve/diagnostics.rs

@@ -49,6 +49,88 @@ about what constitutes an Item declaration and what does not:
 http://doc.rust-lang.org/reference.html#statements
 "##,
 
+E0251: r##"
+Two items of the same name cannot be imported without rebinding one of the
+items under a new local name.
+
+An example of this error:
+
+```
+use foo::baz;
+use bar::*; // error, do `use foo::baz as quux` instead on the previous line
+
+fn main() {}
+
+mod foo {
+    pub struct baz;
+}
+
+mod bar {
+    pub mod baz {}
+}
+```
+"##,
+
+E0252: r##"
+Two items of the same name cannot be imported without rebinding one of the
+items under a new local name.
+
+An example of this error:
+
+```
+use foo::baz;
+use bar::baz; // error, do `use bar::baz as quux` instead
+
+fn main() {}
+
+mod foo {
+    pub struct baz;
+}
+
+mod bar {
+    pub mod baz {}
+}
+```
+"##,
+
+E0255: r##"
+You can't import a value whose name is the same as another value defined in the
+module.
+
+An example of this error:
+
+```
+use bar::foo; // error, do `use bar::foo as baz` instead
+
+fn foo() {}
+
+mod bar {
+     pub fn foo() {}
+}
+
+fn main() {}
+```
+"##,
+
+E0256: r##"
+You can't import a type or module when the name of the item being imported is
+the same as another type or submodule defined in the module.
+
+An example of this error:
+
+```
+use foo::Bar; // error
+
+type Bar = u32;
+
+mod foo {
+    pub mod Bar { }
+}
+
+fn main() {}
+```
+"##,
+
 E0259: r##"
 The name chosen for an external crate conflicts with another external crate that
 has been imported into the current module.
@@ -122,14 +204,10 @@ http://doc.rust-lang.org/reference.html#types
 register_diagnostics! {
     E0157,
     E0153,
-    E0251, // a named type or value has already been imported in this module
-    E0252, // a named type or value has already been imported in this module
     E0253, // not directly importable
     E0254, // import conflicts with imported crate in this module
-    E0255, // import conflicts with value in this module
-    E0256, // import conflicts with type in this module
-    E0257, // inherent implementations are only allowed on types defined in the current module
-    E0258, // import conflicts with existing submodule
+    E0257,
+    E0258,
     E0364, // item is private
     E0365  // item is private
 }

src/librustc_typeck/check/mod.rs

@@ -3082,8 +3082,8 @@ fn check_expr_with_unifier<'a, 'tcx, F>(fcx: &FnCtxt<'a, 'tcx>,
           let mut checked = false;
           opt_place.as_ref().map(|place| match place.node {
               ast::ExprPath(None, ref path) => {
-                  // FIXME(pcwalton): For now we hardcode the two permissible
-                  // places: the exchange heap and the managed heap.
+                  // FIXME(pcwalton): For now we hardcode the only permissible
+                  // place: the exchange heap.
                   let definition = lookup_full_def(tcx, path.span, place.id);
                   let def_id = definition.def_id();
                   let referent_ty = fcx.expr_ty(&**subexpr);
@@ -3097,7 +3097,7 @@ fn check_expr_with_unifier<'a, 'tcx, F>(fcx: &FnCtxt<'a, 'tcx>,
 
           if !checked {
               span_err!(tcx.sess, expr.span, E0066,
-                  "only the managed heap and exchange heap are currently supported");
+                  "only the exchange heap is currently supported");
               fcx.write_ty(id, tcx.types.err);
           }
       }
@@ -3317,7 +3317,8 @@ fn check_expr_with_unifier<'a, 'tcx, F>(fcx: &FnCtxt<'a, 'tcx>,
                         if let Err(_) = fcx.mk_eqty(false, infer::Misc(expr.span),
                                                     result_type, ty::mk_nil(fcx.tcx())) {
                             span_err!(tcx.sess, expr.span, E0069,
-                                "`return;` in function returning non-nil");
+                                "`return;` in a function whose return type is \
+                                 not `()`");
                         },
                     Some(ref e) => {
                         check_expr_coercable_to_type(fcx, &**e, result_type);