diff --git a/library/core/src/mem/mod.rs b/library/core/src/mem/mod.rs
index d8521e79006e3..b321908fd9e77 100644
--- a/library/core/src/mem/mod.rs
+++ b/library/core/src/mem/mod.rs
@@ -1,7 +1,32 @@
-//! Basic functions for dealing with memory.
+//! Basic functions for dealing with memory, values, and types.
 //!
-//! This module contains functions for querying the size and alignment of
-//! types, initializing and manipulating memory.
+//! The contents of this module can be seen as belonging to a few families:
+//!
+//! * [`drop`], [`replace`], [`swap`], and [`take`]
+//!   are safe functions for moving values in particular ways.
+//!   They are useful in everyday Rust code.
+//!
+//! * [`size_of`], [`size_of_val`], [`align_of`], [`align_of_val`], and [`offset_of`]
+//!   give information about the representation of values in memory.
+//!
+//! * [`discriminant`]
+//!   allows comparing the variants of [`enum`] values while ignoring their fields.
+//!
+//! * [`forget`] and [`ManuallyDrop`]
+//!   prevent destructors from running, which is used in certain kinds of ownership transfer.
+//!   [`needs_drop`]
+//!   tells you whether a type’s destructor even does anything.
+//!
+//! * [`transmute`], [`transmute_copy`], and [`MaybeUninit`]
+//!   convert and construct values in [`unsafe`] ways.
+//!
+//! See also the [`alloc`] and [`ptr`] modules for more primitive operations on memory.
+//!
+// core::alloc exists but doesn’t contain all the items we want to discuss
+//! [`alloc`]: ../../std/alloc/index.html
+//! [`enum`]: ../../std/keyword.enum.html
+//! [`ptr`]: crate::ptr
+//! [`unsafe`]: ../../std/keyword.unsafe.html
 
 #![stable(feature = "rust1", since = "1.0.0")]
 
diff --git a/tests/ui/binding/match-naked-record.rs b/tests/ui/binding/match-naked-record.rs
deleted file mode 100644
index ce9489a00f2c6..0000000000000
--- a/tests/ui/binding/match-naked-record.rs
+++ /dev/null
@@ -1,12 +0,0 @@
-//@ run-pass
-#![allow(dead_code)]
-
-struct X { x: isize }
-
-pub fn main() {
-    let _x = match 0 {
-      _ => X {
-        x: 0
-      }
-    };
-}
diff --git a/tests/ui/issues/issue-4830.rs b/tests/ui/issues/issue-4830.rs
deleted file mode 100644
index d48c13fd10b1d..0000000000000
--- a/tests/ui/issues/issue-4830.rs
+++ /dev/null
@@ -1,10 +0,0 @@
-//@ check-pass
-#![allow(dead_code)]
-
-
-pub struct Scheduler {
-    /// The event loop used to drive the scheduler and perform I/O
-    event_loop: Box<isize>
-}
-
-pub fn main() { }
diff --git a/tests/ui/issues/issue-5192.rs b/tests/ui/issues/issue-5192.rs
deleted file mode 100644
index be5d70f09b3c0..0000000000000
--- a/tests/ui/issues/issue-5192.rs
+++ /dev/null
@@ -1,38 +0,0 @@
-//@ run-pass
-#![allow(dead_code)]
-
-pub trait EventLoop {
-    fn dummy(&self) { }
-}
-
-pub struct UvEventLoop {
-    uvio: isize
-}
-
-impl UvEventLoop {
-    pub fn new() -> UvEventLoop {
-        UvEventLoop {
-            uvio: 0
-        }
-    }
-}
-
-impl EventLoop for UvEventLoop {
-}
-
-pub struct Scheduler {
-    event_loop: Box<dyn EventLoop+'static>,
-}
-
-impl Scheduler {
-
-    pub fn new(event_loop: Box<dyn EventLoop+'static>) -> Scheduler {
-        Scheduler {
-            event_loop: event_loop,
-        }
-    }
-}
-
-pub fn main() {
-    let _sched = Scheduler::new(Box::new(UvEventLoop::new()) as Box<dyn EventLoop>);
-}
diff --git a/tests/ui/macros/unreachable.rs b/tests/ui/macros/unreachable.rs
deleted file mode 100644
index c5cea5551cfcf..0000000000000
--- a/tests/ui/macros/unreachable.rs
+++ /dev/null
@@ -1,7 +0,0 @@
-//@ run-fail
-//@ error-pattern:internal error: entered unreachable code
-//@ needs-subprocess
-
-fn main() {
-    unreachable!()
-}
diff --git a/tests/ui/moves/array-copy-move.rs b/tests/ui/moves/array-copy-move.rs
deleted file mode 100644
index ea95bc06a3693..0000000000000
--- a/tests/ui/moves/array-copy-move.rs
+++ /dev/null
@@ -1,8 +0,0 @@
-//! regression test for issue https://github.com/rust-lang/rust/issues/16783
-//@ run-pass
-#![allow(unused_variables)]
-
-pub fn main() {
-    let x = [1, 2, 3];
-    let y = x;
-}