Auto merge of #50345 - kennytm:rollup, r=kennytm

Rollup of 7 pull requests

Successful merges:

 - #50233 (Make `Vec::new` a `const fn`)
 - #50312 (Add more links in panic docs)
 - #50316 (Fix some broken links in docs.)
 - #50325 (Add a few more tests for proc macro feature gating)
 - #50327 (Display correct unused field suggestion for nested struct patterns)
 - #50330 (check that #[used] is used only on statics)
 - #50344 (Update Cargo to 2018-04-28 122fd5be5201913d42e219e132d6569493583bca)

Failed merges:

5 files changed, 172 insertions, 19 deletions

diff --git a/src/test/compile-fail-fulldeps/proc-macro/proc-macro-gates.rs b/src/test/compile-fail-fulldeps/proc-macro/proc-macro-gates.rs
index 0dc1c2ab2da..fff433b90ce 100644
--- a/src/test/compile-fail-fulldeps/proc-macro/proc-macro-gates.rs
+++ b/src/test/compile-fail-fulldeps/proc-macro/proc-macro-gates.rs
@@ -24,9 +24,17 @@ use foo::*;
 #[foo::a] //~ ERROR: paths of length greater than one
 fn _test() {}
 
+fn _test_inner() {
+    #![a] // OK
+}
+
 #[a] //~ ERROR: custom attributes cannot be applied to modules
 mod _test2 {}
 
+mod _test2_inner {
+    #![a] //~ ERROR: custom attributes cannot be applied to modules
+}
+
 #[a = y] //~ ERROR: must only be followed by a delimiter token
 fn _test3() {}
 
@@ -36,19 +44,40 @@ fn _test4() {}
 #[a () = ] //~ ERROR: must only be followed by a delimiter token
 fn _test5() {}
 
-fn main() {
+fn attrs() {
+    // Statement, item
+    #[a] // OK
+    struct S;
+
+    // Statement, macro
+    #[a] //~ ERROR: custom attributes cannot be applied to statements
+    println!();
+
+    // Statement, semi
+    #[a] //~ ERROR: custom attributes cannot be applied to statements
+    S;
+
+    // Statement, local
     #[a] //~ ERROR: custom attributes cannot be applied to statements
     let _x = 2;
-    let _x = #[a] 2;
-    //~^ ERROR: custom attributes cannot be applied to expressions
-
-    let _x: m!(u32) = 3;
-    //~^ ERROR: procedural macros cannot be expanded to types
-    if let m!(Some(_x)) = Some(3) {
-    //~^ ERROR: procedural macros cannot be expanded to patterns
-    }
-    let _x = m!(3);
-    //~^ ERROR: procedural macros cannot be expanded to expressions
-    m!(let _x = 3;);
-    //~^ ERROR: procedural macros cannot be expanded to statements
+
+    // Expr
+    let _x = #[a] 2; //~ ERROR: custom attributes cannot be applied to expressions
+
+    // Opt expr
+    let _x = [#[a] 2]; //~ ERROR: custom attributes cannot be applied to expressions
+
+    // Expr macro
+    let _x = #[a] println!(); //~ ERROR: custom attributes cannot be applied to expressions
+}
+
+fn main() {
+    let _x: m!(u32) = 3; //~ ERROR: procedural macros cannot be expanded to types
+    if let m!(Some(_x)) = Some(3) {} //~ ERROR: procedural macros cannot be expanded to patterns
+
+    m!(struct S;); //~ ERROR: procedural macros cannot be expanded to statements
+    m!(let _x = 3;); //~ ERROR: procedural macros cannot be expanded to statements
+
+    let _x = m!(3); //~ ERROR: procedural macros cannot be expanded to expressions
+    let _x = [m!(3)]; //~ ERROR: procedural macros cannot be expanded to expressions
 }
diff --git a/src/test/compile-fail/used.rs b/src/test/compile-fail/used.rs
new file mode 100644
index 00000000000..f170d9c25f5
--- /dev/null
+++ b/src/test/compile-fail/used.rs
@@ -0,0 +1,28 @@
+// Copyright 2018 The Rust Project Developers. See the COPYRIGHT
+// file at the top-level directory of this distribution and at
+// http://rust-lang.org/COPYRIGHT.
+//
+// Licensed under the Apache License, Version 2.0 <LICENSE-APACHE or
+// http://www.apache.org/licenses/LICENSE-2.0> or the MIT license
+// <LICENSE-MIT or http://opensource.org/licenses/MIT>, at your
+// option. This file may not be copied, modified, or distributed
+// except according to those terms.
+
+#![feature(used)]
+
+#[used]
+static FOO: u32 = 0; // OK
+
+#[used] //~ ERROR attribute must be applied to a `static` variable
+fn foo() {}
+
+#[used] //~ ERROR attribute must be applied to a `static` variable
+struct Foo {}
+
+#[used] //~ ERROR attribute must be applied to a `static` variable
+trait Bar {}
+
+#[used] //~ ERROR attribute must be applied to a `static` variable
+impl Bar for Foo {}
+
+fn main() {}
diff --git a/src/test/run-pass/vec-const-new.rs b/src/test/run-pass/vec-const-new.rs
new file mode 100644
index 00000000000..62e2a36d7cc
--- /dev/null
+++ b/src/test/run-pass/vec-const-new.rs
@@ -0,0 +1,17 @@
+// Copyright 2012 The Rust Project Developers. See the COPYRIGHT
+// file at the top-level directory of this distribution and at
+// http://rust-lang.org/COPYRIGHT.
+//
+// Licensed under the Apache License, Version 2.0 <LICENSE-APACHE or
+// http://www.apache.org/licenses/LICENSE-2.0> or the MIT license
+// <LICENSE-MIT or http://opensource.org/licenses/MIT>, at your
+// option. This file may not be copied, modified, or distributed
+// except according to those terms.
+
+// Test that Vec::new() can be used for constants
+
+#![feature(const_vec_new)]
+
+const MY_VEC: Vec<usize> = Vec::new();
+
+pub fn main() {}
diff --git a/src/test/ui/lint/issue-47390-unused-variable-in-struct-pattern.rs b/src/test/ui/lint/issue-47390-unused-variable-in-struct-pattern.rs
index 18b83370355..6994a377a06 100644
--- a/src/test/ui/lint/issue-47390-unused-variable-in-struct-pattern.rs
+++ b/src/test/ui/lint/issue-47390-unused-variable-in-struct-pattern.rs
@@ -10,6 +10,8 @@
 
 // compile-pass
 
+#![feature(box_syntax)]
+#![feature(box_patterns)]
 #![warn(unused)] // UI tests pass `-A unused` (#43896)
 
 struct SoulHistory {
@@ -18,6 +20,13 @@ struct SoulHistory {
     endless_and_singing: bool
 }
 
+#[derive(Clone, Copy)]
+enum Large {
+    Suit { case: () }
+}
+
+struct Tuple(Large, ());
+
 fn main() {
     let i_think_continually = 2;
     let who_from_the_womb_remembered = SoulHistory {
@@ -31,4 +40,38 @@ fn main() {
                          endless_and_singing: true } = who_from_the_womb_remembered {
         hours_are_suns = false;
     }
+
+    let bag = Large::Suit {
+        case: ()
+    };
+
+    // Plain struct
+    match bag {
+        Large::Suit { case } => {}
+    };
+
+    // Referenced struct
+    match &bag {
+        &Large::Suit { case } => {}
+    };
+
+    // Boxed struct
+    match box bag {
+        box Large::Suit { case } => {}
+    };
+
+    // Tuple with struct
+    match (bag,) {
+        (Large::Suit { case },) => {}
+    };
+
+    // Slice with struct
+    match [bag] {
+        [Large::Suit { case }] => {}
+    };
+
+    // Tuple struct with struct
+    match Tuple(bag, ()) {
+        Tuple(Large::Suit { case }, ()) => {}
+    };
 }
diff --git a/src/test/ui/lint/issue-47390-unused-variable-in-struct-pattern.stderr b/src/test/ui/lint/issue-47390-unused-variable-in-struct-pattern.stderr
index 35fe5479406..7bfe2c9162e 100644
--- a/src/test/ui/lint/issue-47390-unused-variable-in-struct-pattern.stderr
+++ b/src/test/ui/lint/issue-47390-unused-variable-in-struct-pattern.stderr
@@ -1,24 +1,24 @@
 warning: unused variable: `i_think_continually`
-  --> $DIR/issue-47390-unused-variable-in-struct-pattern.rs:22:9
+  --> $DIR/issue-47390-unused-variable-in-struct-pattern.rs:31:9
    |
 LL |     let i_think_continually = 2;
    |         ^^^^^^^^^^^^^^^^^^^ help: consider using `_i_think_continually` instead
    |
 note: lint level defined here
-  --> $DIR/issue-47390-unused-variable-in-struct-pattern.rs:13:9
+  --> $DIR/issue-47390-unused-variable-in-struct-pattern.rs:15:9
    |
 LL | #![warn(unused)] // UI tests pass `-A unused` (#43896)
    |         ^^^^^^
    = note: #[warn(unused_variables)] implied by #[warn(unused)]
 
 warning: unused variable: `corridors_of_light`
-  --> $DIR/issue-47390-unused-variable-in-struct-pattern.rs:29:26
+  --> $DIR/issue-47390-unused-variable-in-struct-pattern.rs:38:26
    |
 LL |     if let SoulHistory { corridors_of_light,
    |                          ^^^^^^^^^^^^^^^^^^ help: try ignoring the field: `corridors_of_light: _`
 
 warning: variable `hours_are_suns` is assigned to, but never used
-  --> $DIR/issue-47390-unused-variable-in-struct-pattern.rs:30:26
+  --> $DIR/issue-47390-unused-variable-in-struct-pattern.rs:39:26
    |
 LL |                          mut hours_are_suns,
    |                          ^^^^^^^^^^^^^^^^^^
@@ -26,15 +26,51 @@ LL |                          mut hours_are_suns,
    = note: consider using `_hours_are_suns` instead
 
 warning: value assigned to `hours_are_suns` is never read
-  --> $DIR/issue-47390-unused-variable-in-struct-pattern.rs:32:9
+  --> $DIR/issue-47390-unused-variable-in-struct-pattern.rs:41:9
    |
 LL |         hours_are_suns = false;
    |         ^^^^^^^^^^^^^^
    |
 note: lint level defined here
-  --> $DIR/issue-47390-unused-variable-in-struct-pattern.rs:13:9
+  --> $DIR/issue-47390-unused-variable-in-struct-pattern.rs:15:9
    |
 LL | #![warn(unused)] // UI tests pass `-A unused` (#43896)
    |         ^^^^^^
    = note: #[warn(unused_assignments)] implied by #[warn(unused)]
 
+warning: unused variable: `case`
+  --> $DIR/issue-47390-unused-variable-in-struct-pattern.rs:50:23
+   |
+LL |         Large::Suit { case } => {}
+   |                       ^^^^ help: try ignoring the field: `case: _`
+
+warning: unused variable: `case`
+  --> $DIR/issue-47390-unused-variable-in-struct-pattern.rs:55:24
+   |
+LL |         &Large::Suit { case } => {}
+   |                        ^^^^ help: try ignoring the field: `case: _`
+
+warning: unused variable: `case`
+  --> $DIR/issue-47390-unused-variable-in-struct-pattern.rs:60:27
+   |
+LL |         box Large::Suit { case } => {}
+   |                           ^^^^ help: try ignoring the field: `case: _`
+
+warning: unused variable: `case`
+  --> $DIR/issue-47390-unused-variable-in-struct-pattern.rs:65:24
+   |
+LL |         (Large::Suit { case },) => {}
+   |                        ^^^^ help: try ignoring the field: `case: _`
+
+warning: unused variable: `case`
+  --> $DIR/issue-47390-unused-variable-in-struct-pattern.rs:70:24
+   |
+LL |         [Large::Suit { case }] => {}
+   |                        ^^^^ help: try ignoring the field: `case: _`
+
+warning: unused variable: `case`
+  --> $DIR/issue-47390-unused-variable-in-struct-pattern.rs:75:29
+   |
+LL |         Tuple(Large::Suit { case }, ()) => {}
+   |                             ^^^^ help: try ignoring the field: `case: _`
+