diff --git a/src/rust-2018/data-types/inclusive-ranges.md b/src/rust-2018/data-types/inclusive-ranges.md
index ee460caa..740877d5 100644
--- a/src/rust-2018/data-types/inclusive-ranges.md
+++ b/src/rust-2018/data-types/inclusive-ranges.md
@@ -5,7 +5,7 @@
 Since well before Rust 1.0, you’ve been able to create exclusive ranges with
 `..` like this:
 
-```
+```rust
 for i in 1..3 {
     println!("i: {}", i);
 }
diff --git a/src/rust-2018/edition-changes.md b/src/rust-2018/edition-changes.md
index 4e3288e2..7c4d1762 100644
--- a/src/rust-2018/edition-changes.md
+++ b/src/rust-2018/edition-changes.md
@@ -11,9 +11,11 @@ the 2018 edition compared to the 2015 edition.
 - [Anonymous trait function parameters] are not allowed.
     - [Trait function parameters] may use any irrefutable pattern when the
       function has a body.
-- [`dyn`] is a [strict keyword], in 2015 it is a [weak keyword].
-- `async`, `await`, and `try` are [reserved keywords].
-- The following lints are now deny by default:
+- Keyword changes:
+    - [`dyn`] is a [strict keyword][strict], in 2015 it is a [weak keyword].
+    - `async` and `await` are [strict keywords][strict].
+    - `try` is a [reserved keyword].
+- The following lints are now a hard error that you cannot silence:
     - [tyvar_behind_raw_pointer]
 
 ## Cargo
@@ -28,7 +30,7 @@ the 2018 edition compared to the 2015 edition.
 [Path changes]: module-system/path-clarity.md
 [Trait function parameters]: https://doc.rust-lang.org/stable/reference/items/traits.html#parameter-patterns
 [`dyn`]: trait-system/dyn-trait-for-trait-objects.md
-[reserved keywords]: https://doc.rust-lang.org/reference/keywords.html#reserved-keywords
-[strict keyword]: https://doc.rust-lang.org/reference/keywords.html#strict-keywords
+[reserved keyword]: https://doc.rust-lang.org/reference/keywords.html#reserved-keywords
+[strict]: https://doc.rust-lang.org/reference/keywords.html#strict-keywords
 [tyvar_behind_raw_pointer]: https://github.com/rust-lang/rust/issues/46906
 [weak keyword]: https://doc.rust-lang.org/reference/keywords.html#weak-keywords
diff --git a/src/rust-2018/module-system/path-clarity.md b/src/rust-2018/module-system/path-clarity.md
index 19bbf739..0a87e46d 100644
--- a/src/rust-2018/module-system/path-clarity.md
+++ b/src/rust-2018/module-system/path-clarity.md
@@ -65,26 +65,40 @@ keep doing what you were doing there as well.
 #### An exception
 
 There's one exception to this rule, and that's the "sysroot" crates. These are the
-crates distributed with Rust itself. We'd eventually like to remove the requirement
-for `extern crate` for them as well, but it hasn't shipped yet.
-
-You'll need to use `extern crate` for:
-
-* `proc_macro`
-
-Additionally, you would need to use it for:
-
-* `core`
-* `std`
-
-However, `extern crate std;` is already implicit, and with `#![no_std]`,
-`extern crate core;` is already implicit. You'll only need these in highly
-specialized situations.
-
-Finally, on nightly, you'll need it for crates like:
-
-* `alloc`
-* `test`
+crates distributed with Rust itself.
+
+Usually these are only needed in very specialized situations. Starting in
+1.41, `rustc` accepts the `--extern=CRATE_NAME` flag which automatically adds
+the given crate name in a way similar to `extern crate`. Build tools may use
+this to inject sysroot crates into the crate's prelude. Cargo does not have a
+general way to express this, though it uses it for `proc_macro` crates.
+
+Some examples of needing to explicitly import sysroot crates are:
+
+* [`std`]: Usually this is not neccesary, because `std` is automatically
+  imported unless the crate is marked with [`#![no_std]`][no_std].
+* [`core`]: Usually this is not necessary, because `core` is automatically
+  imported, unless the crate is marked with [`#![no_core]`][no_core]. For
+  example, some of the internal crates used by the standard library itself
+  need this.
+* [`proc_macro`]: This is automatically imported by Cargo if it is a
+  proc-macro crate starting in 1.42. `extern crate proc_macro;` would be
+  needed if you want to support older releases, or if using another build tool
+  that does not pass the appropriate `--extern` flags to `rustc`.
+* [`alloc`]: Items in the `alloc` crate are usually accessed via re-exports in
+  the `std` crate. If you are working with a `no_std` crate that supports
+  allocation, then you may need to explicitly import `alloc`.
+* [`test`]: This is only available on the [nightly channel], and is usually
+  only used for the unstable benchmark support.
+
+[`alloc`]: ../../../alloc/index.html
+[`core`]: ../../../core/index.html
+[`proc_macro`]: ../../../proc_macro/index.html
+[`std`]: ../../../std/index.html
+[`test`]: ../../../test/index.html
+[nightly channel]: ../../../book/appendix-07-nightly-rust.html
+[no_core]: https://github.com/rust-lang/rust/issues/29639
+[no_std]: ../../../reference/crates-and-source-files.html#preludes-and-no_std
 
 #### Macros
 
diff --git a/src/rust-2018/rustdoc/documentation-tests-can-now-compile-fail.md b/src/rust-2018/rustdoc/documentation-tests-can-now-compile-fail.md
index 35207c61..7fbf4fb7 100644
--- a/src/rust-2018/rustdoc/documentation-tests-can-now-compile-fail.md
+++ b/src/rust-2018/rustdoc/documentation-tests-can-now-compile-fail.md
@@ -4,7 +4,7 @@
 
 You can now create `compile-fail` tests in Rustdoc, like this:
 
-```
+```rust
 /// ```compile_fail
 /// let x = 5;
 /// x += 2; // shouldn't compile!
diff --git a/src/rust-next/const-fn.md b/src/rust-next/const-fn.md
index 65f640f7..13bb50bc 100644
--- a/src/rust-next/const-fn.md
+++ b/src/rust-next/const-fn.md
@@ -6,7 +6,7 @@ Expanded in many releases, see each aspect below for more details.
 
 A `const fn` allows you to execute code in a "const context." For example:
 
-```
+```rust
 const fn five() -> i32 {
     5
 }
@@ -34,7 +34,7 @@ that it is becoming more `const` over time.
 
 You can do arithmetic on integer literals:
 
-```
+```rust
 const fn foo() -> i32 {
     5 + 6
 }
@@ -46,7 +46,7 @@ const fn foo() -> i32 {
 
 You can use boolean operators other than `&&` and `||`, because they short-circut evaluation:
 
-```
+```rust
 const fn mask(val: u8) -> u8 {
     let mask = 0x0f;
 
@@ -60,7 +60,7 @@ const fn mask(val: u8) -> u8 {
 
 You can create arrays, structs, enums, and tuples:
 
-```
+```rust
 struct Point {
     x: i32,
     y: i32,
@@ -92,7 +92,7 @@ const fn foo() {
 You can call `const fn` from a `const fn`:
 
 
-```
+```rust
 const fn foo() -> i32 {
     5
 }
@@ -108,7 +108,7 @@ const fn bar() -> i32 {
 
 You can index into an array or slice:
 
-```
+```rust
 const fn foo() -> i32 {
     let array = [1, 2, 3];
 
@@ -122,7 +122,7 @@ const fn foo() -> i32 {
 
 You can access parts of a struct or tuple:
 
-```
+```rust
 struct Point {
     x: i32,
     y: i32,
@@ -147,7 +147,7 @@ const fn foo() {
 
 You can read from a constant:
 
-```
+```rust
 const FOO: i32 = 5;
 
 const fn foo() -> i32 {
@@ -163,7 +163,7 @@ Note that this is *only* `const`, not `static`.
 
 You can create and de-reference references:
 
-```
+```rust
 const fn foo(r: &i32) {
     *r;
 
@@ -177,7 +177,7 @@ const fn foo(r: &i32) {
 
 You may cast things, except for raw pointers may not be casted to an integer:
 
-```
+```rust
 const fn foo() {
     let x: usize = 5;
 
@@ -191,7 +191,7 @@ const fn foo() {
 
 You can use irrefutable patterns that destructure values. For example:
 
-```
+```rust
 const fn foo((x, y): (u8, u8)) {
     // ...
 }
@@ -206,7 +206,7 @@ place that uses irrefutable patterns.
 
 You can use both mutable and immutable `let` bindings:
 
-```
+```rust
 const fn foo() {
     let x = 5;
     let mut y = 10;
@@ -219,7 +219,7 @@ const fn foo() {
 
 You can use assignment and assignment operators:
 
-```
+```rust
 const fn foo() {
     let mut x = 5;
     x = 10;
@@ -232,7 +232,7 @@ const fn foo() {
 
 You can call an `unsafe fn` inside a `const fn`:
 
-```
+```rust
 const unsafe fn foo() -> i32 { 5 }
 
 const fn bar() -> i32 {