Auto merge of #46538 - frewsxcv:rollup, r=frewsxcv

Rollup of 7 pull requests

- Successful merges: #46136, #46378, #46431, #46483, #46495, #46502, #46512
- Failed merges:

9 files changed, 87 insertions, 15 deletions

diff --git a/CONTRIBUTING.md b/CONTRIBUTING.md
index e3767df2808..b8fea40090f 100644
--- a/CONTRIBUTING.md
+++ b/CONTRIBUTING.md
@@ -336,7 +336,7 @@ will run all the tests on every platform we support. If it all works out,
 
 Speaking of tests, Rust has a comprehensive test suite. More information about
 it can be found
-[here](https://github.com/rust-lang/rust-wiki-backup/blob/master/Note-testsuite.md).
+[here](https://github.com/rust-lang/rust/blob/master/src/test/COMPILER_TESTS.md).
 
 ### External Dependencies
 [external-dependencies]: #external-dependencies
diff --git a/src/liballoc/benches/btree/map.rs b/src/liballoc/benches/btree/map.rs
index 744afb991b0..20b9091a07b 100644
--- a/src/liballoc/benches/btree/map.rs
+++ b/src/liballoc/benches/btree/map.rs
@@ -12,7 +12,7 @@
 use std::iter::Iterator;
 use std::vec::Vec;
 use std::collections::BTreeMap;
-use std::__rand::{Rng, thread_rng};
+use rand::{Rng, thread_rng};
 use test::{Bencher, black_box};
 
 macro_rules! map_insert_rand_bench {
diff --git a/src/liballoc/benches/slice.rs b/src/liballoc/benches/slice.rs
index d99270e7f31..17538d885f8 100644
--- a/src/liballoc/benches/slice.rs
+++ b/src/liballoc/benches/slice.rs
@@ -8,7 +8,7 @@
 // option. This file may not be copied, modified, or distributed
 // except according to those terms.
 
-use std::__rand::{thread_rng};
+use rand::{thread_rng};
 use std::mem;
 use std::ptr;
 
diff --git a/src/libcore/macros.rs b/src/libcore/macros.rs
index 6e3dbcbec9d..fe2df226115 100644
--- a/src/libcore/macros.rs
+++ b/src/libcore/macros.rs
@@ -596,9 +596,9 @@ mod builtin {
 
     /// Unconditionally causes compilation to fail with the given error message when encountered.
     ///
-    /// For more information, see the [RFC].
+    /// For more information, see the documentation for [`std::compile_error!`].
     ///
-    /// [RFC]: https://github.com/rust-lang/rfcs/blob/master/text/1695-add-error-macro.md
+    /// [`std::compile_error!`]: ../std/macro.compile_error.html
     #[stable(feature = "compile_error_macro", since = "1.20.0")]
     #[macro_export]
     #[cfg(dox)]
diff --git a/src/libcore/ptr.rs b/src/libcore/ptr.rs
index 5e70c8283f4..20f054f5a77 100644
--- a/src/libcore/ptr.rs
+++ b/src/libcore/ptr.rs
@@ -91,8 +91,12 @@ pub const fn null<T>() -> *const T { 0 as *const T }
 pub const fn null_mut<T>() -> *mut T { 0 as *mut T }
 
 /// Swaps the values at two mutable locations of the same type, without
-/// deinitializing either. They may overlap, unlike `mem::swap` which is
-/// otherwise equivalent.
+/// deinitializing either.
+///
+/// The values pointed at by `x` and `y` may overlap, unlike `mem::swap` which
+/// is otherwise equivalent. If the values do overlap, then the overlapping
+/// region of memory from `x` will be used. This is demonstrated in the
+/// examples section below.
 ///
 /// # Safety
 ///
@@ -100,6 +104,40 @@ pub const fn null_mut<T>() -> *mut T { 0 as *mut T }
 /// as arguments.
 ///
 /// Ensure that these pointers are valid before calling `swap`.
+///
+/// # Examples
+///
+/// Swapping two non-overlapping regions:
+///
+/// ```
+/// use std::ptr;
+///
+/// let mut array = [0, 1, 2, 3];
+///
+/// let x = array[0..].as_mut_ptr() as *mut [u32; 2];
+/// let y = array[2..].as_mut_ptr() as *mut [u32; 2];
+///
+/// unsafe {
+///     ptr::swap(x, y);
+///     assert_eq!([2, 3, 0, 1], array);
+/// }
+/// ```
+///
+/// Swapping two overlapping regions:
+///
+/// ```
+/// use std::ptr;
+///
+/// let mut array = [0, 1, 2, 3];
+///
+/// let x = array[0..].as_mut_ptr() as *mut [u32; 3];
+/// let y = array[1..].as_mut_ptr() as *mut [u32; 3];
+///
+/// unsafe {
+///     ptr::swap(x, y);
+///     assert_eq!([1, 0, 1, 2], array);
+/// }
+/// ```
 #[inline]
 #[stable(feature = "rust1", since = "1.0.0")]
 pub unsafe fn swap<T>(x: *mut T, y: *mut T) {
diff --git a/src/libcore/result.rs b/src/libcore/result.rs
index db5bffced10..959935242dc 100644
--- a/src/libcore/result.rs
+++ b/src/libcore/result.rs
@@ -153,12 +153,12 @@
 //! }
 //! ```
 //!
-//! # The `?` syntax
+//! # The question mark operator, `?`
 //!
 //! When writing code that calls many functions that return the
-//! [`Result`] type, the error handling can be tedious. The [`?`]
-//! syntax hides some of the boilerplate of propagating errors up the
-//! call stack.
+//! [`Result`] type, the error handling can be tedious. The question mark
+//! operator, [`?`], hides some of the boilerplate of propagating errors
+//! up the call stack.
 //!
 //! It replaces this:
 //!
diff --git a/src/librustc_driver/lib.rs b/src/librustc_driver/lib.rs
index bda721d0783..d9b67e2d27f 100644
--- a/src/librustc_driver/lib.rs
+++ b/src/librustc_driver/lib.rs
@@ -982,7 +982,7 @@ Available lint options:
     println!("Lint groups provided by rustc:\n");
     println!("    {}  {}", padded("name"), "sub-lints");
     println!("    {}  {}", padded("----"), "---------");
-    println!("    {}  {}", padded("warnings"), "all built-in lints");
+    println!("    {}  {}", padded("warnings"), "all lints that are set to issue warnings");
 
     let print_lint_groups = |lints: Vec<(&'static str, Vec<lint::LintId>)>| {
         for (name, to) in lints {
diff --git a/src/librustdoc/html/static/rustdoc.css b/src/librustdoc/html/static/rustdoc.css
index 679f5f6e3fd..f32252b726c 100644
--- a/src/librustdoc/html/static/rustdoc.css
+++ b/src/librustdoc/html/static/rustdoc.css
@@ -179,7 +179,6 @@ nav.sub {
 	top: 0;
 	height: 100vh;
 	overflow: auto;
-	z-index: 1;
 }
 
 .sidebar .current {
@@ -273,9 +272,19 @@ nav.sub {
 	overflow: auto;
 	padding-left: 0;
 }
+
 #search {
 	margin-left: 230px;
+	position: relative;
+}
+
+#results {
+	position: absolute;
+	right: 0;
+	left: 0;
+	overflow: auto;
 }
+
 .content pre.line-numbers {
 	float: left;
 	border: none;
diff --git a/src/libstd/macros.rs b/src/libstd/macros.rs
index 7d62f94056f..b36473d9b75 100644
--- a/src/libstd/macros.rs
+++ b/src/libstd/macros.rs
@@ -282,9 +282,34 @@ pub mod builtin {
 
     /// Unconditionally causes compilation to fail with the given error message when encountered.
     ///
-    /// For more information, see the [RFC].
+    /// This macro should be used when a crate uses a conditional compilation strategy to provide
+    /// better error messages for errornous conditions.
     ///
-    /// [RFC]: https://github.com/rust-lang/rfcs/blob/master/text/1695-add-error-macro.md
+    /// # Examples
+    ///
+    /// Two such examples are macros and `#[cfg]` environments.
+    ///
+    /// Emit better compiler error if a macro is passed invalid values.
+    ///
+    /// ```compile_fail
+    /// macro_rules! give_me_foo_or_bar {
+    ///     (foo) => {};
+    ///     (bar) => {};
+    ///     ($x:ident) => {
+    ///         compile_error!("This macro only accepts `foo` or `bar`");
+    ///     }
+    /// }
+    ///
+    /// give_me_foo_or_bar!(neither);
+    /// // ^ will fail at compile time with message "This macro only accepts `foo` or `bar`"
+    /// ```
+    ///
+    /// Emit compiler error if one of a number of features isn't available.
+    ///
+    /// ```compile_fail
+    /// #[cfg(not(any(feature = "foo", feature = "bar")))]
+    /// compile_error!("Either feature \"foo\" or \"bar\" must be enabled for this crate.")
+    /// ```
     #[stable(feature = "compile_error_macro", since = "1.20.0")]
     #[macro_export]
     macro_rules! compile_error { ($msg:expr) => ({ /* compiler built-in */ }) }