Auto merge of #27512 - Manishearth:rollup, r=Manishearth

- Successful merges: #27397, #27398, #27460, #27470, #27491, #27498, #27502
- Failed merges: 

9 files changed, 127 insertions, 79 deletions

diff --git a/RELEASES.md b/RELEASES.md
index 0c495595511..1dfd2186e13 100644
--- a/RELEASES.md
+++ b/RELEASES.md
@@ -79,7 +79,7 @@ Libraries
   are used by code generators to emit implementations of [`Debug`].
 * `str` has new [`to_uppercase`][strup] and [`to_lowercase`][strlow]
   methods that convert case, following Unicode case mapping.
-* It is now easier to handle to poisoned locks. The [`PoisonError`]
+* It is now easier to handle poisoned locks. The [`PoisonError`]
   type, returned by failing lock operations, exposes `into_inner`,
   `get_ref`, and `get_mut`, which all give access to the inner lock
   guard, and allow the poisoned lock to continue to operate. The
diff --git a/src/doc/trpl/guessing-game.md b/src/doc/trpl/guessing-game.md
index 0cd4c60932a..63a1c10f841 100644
--- a/src/doc/trpl/guessing-game.md
+++ b/src/doc/trpl/guessing-game.md
@@ -98,8 +98,8 @@ use std::io;
 
 We’ll need to take user input, and then print the result as output. As such, we
 need the `io` library from the standard library. Rust only imports a few things
-into every program, [the ‘prelude’][prelude]. If it’s not in the prelude,
-you’ll have to `use` it directly.
+by default into every program, [the ‘prelude’][prelude]. If it’s not in the
+prelude, you’ll have to `use` it directly.
 
 [prelude]: ../std/prelude/index.html
 
diff --git a/src/doc/trpl/hello-cargo.md b/src/doc/trpl/hello-cargo.md
index 8e479977887..4bd7de23f0c 100644
--- a/src/doc/trpl/hello-cargo.md
+++ b/src/doc/trpl/hello-cargo.md
@@ -8,13 +8,13 @@ so it is assumed that Rust projects will use Cargo from the beginning.
 [cratesio]: http://doc.crates.io
 
 Cargo manages three things: building your code, downloading the dependencies
-your code needs, and building those dependencies. At first, your
-program doesn’t have any dependencies, so we’ll only be using the first part of
-its functionality. Eventually, we’ll add more. Since we started off by using
-Cargo, it'll be easy to add later.
+your code needs, and building those dependencies. At first, your program doesn’t
+have any dependencies, so we’ll only be using the first part of its
+functionality. Eventually, we’ll add more. Since we started off by using Cargo,
+it'll be easy to add later.
 
-If you installed Rust via the official installers you will also have Cargo. If
-you installed Rust some other way, you may want to [check the Cargo
+If we installed Rust via the official installers we will also have Cargo. If we
+installed Rust some other way, we may want to [check the Cargo
 README][cargoreadme] for specific instructions about installing it.
 
 [cargoreadme]: https://github.com/rust-lang/cargo#installing-cargo-from-nightlies
@@ -23,20 +23,21 @@ README][cargoreadme] for specific instructions about installing it.
 
 Let’s convert Hello World to Cargo.
 
-To Cargo-ify our project, we need to do two things: Make a `Cargo.toml`
-configuration file, and put our source file in the right place. Let's
-do that part first:
+To Cargo-ify our project, we need to do three things: Make a `Cargo.toml`
+configuration file, put our source file in the right place, and get rid of the
+old executable (`main.exe` on Windows, `main` everywhere else). Let's do that part first:
 
 ```bash
 $ mkdir src
 $ mv main.rs src/main.rs
+$ rm main  # or main.exe on Windows
 ```
 
-Note that since we're creating an executable, we used `main.rs`. If we
-want to make a library instead, we should use `lib.rs`. This convention is required
-for Cargo to successfully compile our projects, but it can be overridden if we wish. 
-Custom file locations for the entry point can be specified
-with a [`[lib]` or `[[bin]]`][crates-custom] key in the TOML file.
+Note that since we're creating an executable, we retain `main.rs` as the source
+filename. If we want to make a library instead, we should use `lib.rs`. This
+convention is used by Cargo to successfully compile our projects, but it can be
+overridden if we wish. Custom file locations for the entry point can be
+specified with a [`[lib]` or `[[bin]]`][crates-custom] key in the TOML file.
 
 [crates-custom]: http://doc.crates.io/manifest.html#configuring-a-target
 
@@ -63,8 +64,8 @@ version = "0.0.1"
 authors = [ "Your name <you@example.com>" ]
 ```
 
-This file is in the [TOML][toml] format. TOML is similar to INI, but has some 
-extra goodies. According to the TOML docs, 
+This file is in the [TOML][toml] format. TOML is similar to INI, but has some
+extra goodies. According to the TOML docs,
 
 > TOML aims to be a minimal configuration file format that's easy to read due
 > to obvious semantics. TOML is designed to map unambiguously to a hash table.
@@ -73,7 +74,8 @@ extra goodies. According to the TOML docs,
 
 [toml]: https://github.com/toml-lang/toml
 
-Once you have this file in place, we should be ready to build! To do so, run:
+Once we have this file in place in our project's root directory, we should be
+ready to build! To do so, run:
 
 ```bash
 $ cargo build
diff --git a/src/doc/trpl/patterns.md b/src/doc/trpl/patterns.md
index 9603eec7aca..1abd4ca6c21 100644
--- a/src/doc/trpl/patterns.md
+++ b/src/doc/trpl/patterns.md
@@ -112,26 +112,55 @@ match x {
 }
 ```
 
-# Ignoring variants
+# Ignoring bindings
 
-If you’re matching on an enum which has variants, you can use `..` to
-ignore the value and type in the variant:
+You can use `_` in a pattern to disregard the type and value.
+For example, here’s a `match` against a `Result<T, E>`:
 
 ```rust
-enum OptionalInt {
-    Value(i32),
+# let some_value: Result<i32, &'static str> = Err("There was an error");
+match some_value {
+    Ok(value) => println!("got a value: {}", value),
+    Err(_) => println!("an error occurred"),
+}
+```
+
+In the first arm, we bind the value inside the `Ok` variant to `value`. But
+in the `Err` arm, we use `_` to disregard the specific error, and just print
+a general error message.
+
+`_` is valid in any pattern that creates a binding. This can be useful to
+ignore parts of a larger structure:
+
+```rust
+fn coordinate() -> (i32, i32, i32) {
+    // generate and return some sort of triple tuple
+# (1, 2, 3)
+}
+
+let (x, _, z) = coordinate();
+```
+
+Here, we bind the first and last element of the tuple to `x` and `z`, but
+ignore the middle element.
+
+Similarly, you can use `..` in a pattern to disregard multiple values.
+
+```rust
+enum OptionalTuple {
+    Value(i32, i32, i32),
     Missing,
 }
 
-let x = OptionalInt::Value(5);
+let x = OptionalTuple::Value(5, -2, 3);
 
 match x {
-    OptionalInt::Value(..) => println!("Got an int!"),
-    OptionalInt::Missing => println!("No such luck."),
+    OptionalTuple::Value(..) => println!("Got a tuple!"),
+    OptionalTuple::Missing => println!("No such luck."),
 }
 ```
 
-This prints `Got an int!`.
+This prints `Got a tuple!`.
 
 # Guards
 
@@ -282,38 +311,6 @@ This ‘destructuring’ behavior works on any compound data type, like
 [tuples]: primitive-types.html#tuples
 [enums]: enums.html
 
-# Ignoring bindings
-
-You can use `_` in a pattern to disregard the value. For example, here’s a
-`match` against a `Result<T, E>`:
-
-```rust
-# let some_value: Result<i32, &'static str> = Err("There was an error");
-match some_value {
-    Ok(value) => println!("got a value: {}", value),
-    Err(_) => println!("an error occurred"),
-}
-```
-
-In the first arm, we bind the value inside the `Ok` variant to `value`. But
-in the `Err` arm, we use `_` to disregard the specific error, and just print
-a general error message.
-
-`_` is valid in any pattern that creates a binding. This can be useful to
-ignore parts of a larger structure:
-
-```rust
-fn coordinate() -> (i32, i32, i32) {
-    // generate and return some sort of triple tuple
-# (1, 2, 3)
-}
-
-let (x, _, z) = coordinate();
-```
-
-Here, we bind the first and last element of the tuple to `x` and `z`, but
-ignore the middle element.
-
 # Mix and Match
 
 Whew! That’s a lot of different ways to match things, and they can all be
diff --git a/src/libcore/mem.rs b/src/libcore/mem.rs
index 3b321d43b3d..7e63c8d71f9 100644
--- a/src/libcore/mem.rs
+++ b/src/libcore/mem.rs
@@ -322,20 +322,16 @@ pub unsafe fn dropped<T>() -> T {
 /// println!("{:?}", &data[0]);
 /// ```
 ///
-/// Hopefully this example emphasizes to you exactly how delicate
-/// and dangerous doing this is. Note that the `vec!` macro
-/// *does* let you initialize every element with a value that
-/// is only `Clone`, so the following is equivalent and vastly
-/// less dangerous, as long as you can live with an extra heap
+/// This example emphasizes exactly how delicate and dangerous doing this is.
+/// Note that the `vec!` macro *does* let you initialize every element with a
+/// value that is only `Clone`, so the following is semantically equivalent and
+/// vastly less dangerous, as long as you can live with an extra heap
 /// allocation:
 ///
 /// ```
 /// let data: Vec<Vec<u32>> = vec![Vec::new(); 1000];
 /// println!("{:?}", &data[0]);
 /// ```
-///
-/// For large arrays this is probably advisable
-/// anyway to avoid blowing the stack.
 #[inline]
 #[stable(feature = "rust1", since = "1.0.0")]
 pub unsafe fn uninitialized<T>() -> T {
diff --git a/src/librustc_resolve/lib.rs b/src/librustc_resolve/lib.rs
index c1f8af1562d..3e22b42836b 100644
--- a/src/librustc_resolve/lib.rs
+++ b/src/librustc_resolve/lib.rs
@@ -313,8 +313,8 @@ fn resolve_error<'b, 'a:'b, 'tcx:'a>(resolver: &'b Resolver<'a, 'tcx>, span: syn
         },
         ResolutionError::StructVariantUsedAsFunction(path_name) => {
             span_err!(resolver.session, span, E0423,
-                         "`{}` is a struct variant name, but \
-                          this expression \
+                         "`{}` is the name of a struct or struct variant, \
+                          but this expression \
                           uses it like a function name",
                           path_name);
         },
diff --git a/src/librustc_typeck/diagnostics.rs b/src/librustc_typeck/diagnostics.rs
index 77256d5b34e..07c1b5e3d20 100644
--- a/src/librustc_typeck/diagnostics.rs
+++ b/src/librustc_typeck/diagnostics.rs
@@ -826,6 +826,63 @@ struct Foo { x: Option<Box<Foo>> }
 Now it's possible to create at least one instance of `Foo`: `Foo { x: None }`.
 "##,
 
+E0074: r##"
+When using the `#[simd]` attribute on a tuple struct, the components of the
+tuple struct must all be of a concrete, nongeneric type so the compiler can
+reason about how to use SIMD with them. This error will occur if the types
+are generic.
+
+```
+#[simd]
+struct Bad<T>(T, T, T); // This will cause an error
+
+#[simd]
+struct Good(u32, u32, u32); // This will not
+```
+"##,
+
+E0075: r##"
+The `#[simd]` attribute can only be applied to non empty tuple structs, because
+it doesn't make sense to try to use SIMD operations when there are no values to
+operate on.
+
+```
+#[simd]
+struct Bad; // This will cause an error
+
+#[simd]
+struct Good(u32); // This will not
+```
+"##,
+
+E0076: r##"
+When using the `#[simd]` attribute to automatically use SIMD operations in tuple
+struct, the types in the struct must all be of the same type, or the compiler
+will trigger this error.
+
+```
+#[simd]
+struct Bad(u16, u32, u32); // This will cause an error
+
+#[simd]
+struct Good(u32, u32, u32); // This will not
+```
+
+"##,
+
+E0077: r##"
+When using the `#[simd]` attribute on a tuple struct, the elements in the tuple
+must be machine types so SIMD operations can be applied to them.
+
+```
+#[simd]
+struct Bad(String); // This will cause an error
+
+#[simd]
+struct Good(u32, u32, u32); // This will not
+```
+"##,
+
 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,
@@ -2378,10 +2435,6 @@ https://doc.rust-lang.org/std/marker/struct.PhantomData.html
 
 register_diagnostics! {
     E0068,
-    E0074,
-    E0075,
-    E0076,
-    E0077,
     E0085,
     E0086,
     E0090,
diff --git a/src/libstd/prelude/mod.rs b/src/libstd/prelude/mod.rs
index 275f415c6fc..4597db41e90 100644
--- a/src/libstd/prelude/mod.rs
+++ b/src/libstd/prelude/mod.rs
@@ -11,8 +11,8 @@
 //! The Rust Prelude
 //!
 //! Because `std` is required by most serious Rust software, it is
-//! imported at the topmost level of every crate by default, as if the
-//! first line of each crate was
+//! imported at the topmost level of every crate by default, as if
+//! each crate contains the following:
 //!
 //! ```ignore
 //! extern crate std;
@@ -23,7 +23,7 @@
 //! etc.
 //!
 //! Additionally, `std` contains a versioned *prelude* that reexports many of the
-//! most common traits, types and functions. *The contents of the prelude are
+//! most common traits, types, and functions. *The contents of the prelude are
 //! imported into every module by default*.  Implicitly, all modules behave as if
 //! they contained the following [`use` statement][book-use]:
 //!
diff --git a/src/test/compile-fail/issue-6702.rs b/src/test/compile-fail/issue-6702.rs
index bfda113ae8b..66ed817ffa8 100644
--- a/src/test/compile-fail/issue-6702.rs
+++ b/src/test/compile-fail/issue-6702.rs
@@ -14,6 +14,6 @@ struct Monster {
 
 
 fn main() {
-    let _m = Monster(); //~ ERROR `Monster` is a struct variant name, but
+    let _m = Monster(); //~ ERROR `Monster` is the name of a struct or
     //~^ HELP did you mean to write: `Monster { /* fields */ }`?
 }