Merge branch 'rust-lang:master' into master

.github/workflows/main.yml

@@ -32,9 +32,9 @@ jobs:
           - build: msrv
             os: ubuntu-20.04
             # sync MSRV with docs: guide/src/guide/installation.md and Cargo.toml
-            rust: 1.60.0
+            rust: 1.65.0
     steps:
-    - uses: actions/checkout@master
+    - uses: actions/checkout@v3
     - name: Install Rust
       run: bash ci/install-rust.sh ${{ matrix.rust }}
     - name: Build and run tests
@@ -46,7 +46,7 @@ jobs:
     name: Rustfmt
     runs-on: ubuntu-latest
     steps:
-    - uses: actions/checkout@master
+    - uses: actions/checkout@v3
     - name: Install Rust
       run: rustup update stable && rustup default stable && rustup component add rustfmt
     - run: cargo fmt --check

CHANGELOG.md

@@ -1,5 +1,53 @@
 # Changelog
 
+## mdBook 0.4.31
+[v0.4.30...v0.4.31](https://github.com/rust-lang/mdBook/compare/v0.4.30...v0.4.31)
+
+### Fixed
+- Fixed menu border render flash during page navigation.
+  [#2101](https://github.com/rust-lang/mdBook/pull/2101)
+- Fixed flicker setting sidebar scroll position.
+  [#2104](https://github.com/rust-lang/mdBook/pull/2104)
+- Fixed compile error with proc-macro2 on latest Rust nightly.
+  [#2109](https://github.com/rust-lang/mdBook/pull/2109)
+
+## mdBook 0.4.30
+[v0.4.29...v0.4.30](https://github.com/rust-lang/mdBook/compare/v0.4.29...v0.4.30)
+
+### Added
+- Added support for heading attributes.
+  Attributes are specified in curly braces just after the heading text.
+  An HTML ID can be specified with `#` and classes with `.`.
+  For example: `## My heading {#custom-id .class1 .class2}`
+  [#2013](https://github.com/rust-lang/mdBook/pull/2013)
+- Added support for hidden code lines for languages other than Rust.
+  The `output.html.code.hidelines` table allows you to define the prefix character that will be used to hide code lines based on the language.
+  [#2093](https://github.com/rust-lang/mdBook/pull/2093)
+
+### Fixed
+- Fixed a few minor markdown rendering issues.
+  [#2092](https://github.com/rust-lang/mdBook/pull/2092)
+
+## mdBook 0.4.29
+[v0.4.28...v0.4.29](https://github.com/rust-lang/mdBook/compare/v0.4.28...v0.4.29)
+
+### Changed
+- Built-in fonts are no longer copied when `fonts/fonts.css` is overridden in the theme directory.
+  Additionally, the warning about `copy-fonts` has been removed if `fonts/fonts.css` is specified.
+  [#2080](https://github.com/rust-lang/mdBook/pull/2080)
+- `mdbook init --force` now skips all interactive prompts as intended.
+  [#2057](https://github.com/rust-lang/mdBook/pull/2057)
+- Updated dependencies
+  [#2063](https://github.com/rust-lang/mdBook/pull/2063)
+  [#2086](https://github.com/rust-lang/mdBook/pull/2086)
+  [#2082](https://github.com/rust-lang/mdBook/pull/2082)
+  [#2084](https://github.com/rust-lang/mdBook/pull/2084)
+  [#2085](https://github.com/rust-lang/mdBook/pull/2085)
+
+### Fixed
+- Switched from the `gitignore` library to `ignore`. This should bring some improvements with gitignore handling.
+  [#2076](https://github.com/rust-lang/mdBook/pull/2076)
+
 ## mdBook 0.4.28
 [v0.4.27...v0.4.28](https://github.com/rust-lang/mdBook/compare/v0.4.27...v0.4.28)
 

Cargo.toml

@@ -1,6 +1,6 @@
 [package]
 name = "mdbook"
-version = "0.4.28"
+version = "0.4.31"
 authors = [
     "Mathieu David <mathieudavid@mathieudavid.org>",
     "Michael-F-Bryan <michaelfbryan@gmail.com>",
@@ -14,55 +14,55 @@ license = "MPL-2.0"
 readme = "README.md"
 repository = "https://github.com/rust-lang/mdBook"
 description = "Creates a book from markdown files"
-rust-version = "1.60"
+rust-version = "1.65"
 
 [dependencies]
-anyhow = "1.0.28"
+anyhow = "1.0.71"
-chrono = { version = "0.4", default-features = false, features = ["clock"] }
+chrono = { version = "0.4.24", default-features = false, features = ["clock"] }
-clap = { version = "4.0.29", features = ["cargo", "wrap_help"] }
+clap = { version = "4.2.7", features = ["cargo", "wrap_help"] }
-clap_complete = "4.0.6"
+clap_complete = "4.2.3"
-once_cell = "1"
+once_cell = "1.17.1"
 env_logger = "0.10.0"
-handlebars = "4.0"
+handlebars = "4.3.7"
-log = "0.4"
+log = "0.4.17"
-memchr = "2.0"
+memchr = "2.5.0"
-opener = "0.5"
+opener = "0.5.2"
-pulldown-cmark = { version = "0.9.1", default-features = false }
+pulldown-cmark = { version = "0.9.3", default-features = false }
-regex = "1.5.5"
+regex = "1.8.1"
-serde = { version = "1.0", features = ["derive"] }
+serde = { version = "1.0.163", features = ["derive"] }
-serde_json = "1.0"
+serde_json = "1.0.96"
-shlex = "1"
+shlex = "1.1.0"
-tempfile = "3.0"
+tempfile = "3.4.0"
-toml = "0.5.1"
+toml = "0.5.11"
 topological-sort = "0.2.2"
 
 # Watch feature
-notify = { version = "5.0.0", optional = true }
+notify = { version = "5.1.0", optional = true }
 notify-debouncer-mini = { version = "0.2.1", optional = true }
-gitignore = { version = "1.0", optional = true }
+ignore = { version = "0.4.20", optional = true }
 
 # Serve feature
-futures-util = { version = "0.3.4", optional = true }
+futures-util = { version = "0.3.28", optional = true }
-tokio = { version = "1", features = ["macros", "rt-multi-thread"], optional = true }
+tokio = { version = "1.28.1", features = ["macros", "rt-multi-thread"], optional = true }
-warp = { version = "0.3.2", default-features = false, features = ["websocket"], optional = true }
+warp = { version = "0.3.5", default-features = false, features = ["websocket"], optional = true }
 
 # Search feature
-elasticlunr-rs = { version = "3.0.0", optional = true }
+elasticlunr-rs = { version = "3.0.2", optional = true }
-ammonia = { version = "3", optional = true }
+ammonia = { version = "3.3.0", optional = true }
 
 [dev-dependencies]
-assert_cmd = "2.0.7"
+assert_cmd = "2.0.11"
-predicates = "2"
+predicates = "2.1.5"
 select = "0.6.0"
-semver = "1.0"
+semver = "1.0.17"
-pretty_assertions = "1.2.1"
+pretty_assertions = "1.3.0"
-walkdir = "2.0"
+walkdir = "2.3.3"
 
 [features]
 default = ["watch", "serve", "search"]
-watch = ["notify", "notify-debouncer-mini", "gitignore"]
+watch = ["dep:notify", "dep:notify-debouncer-mini", "dep:ignore"]
-serve = ["futures-util", "tokio", "warp"]
+serve = ["dep:futures-util", "dep:tokio", "dep:warp"]
-search = ["elasticlunr-rs", "ammonia"]
+search = ["dep:elasticlunr-rs", "dep:ammonia"]
 
 [[bin]]
 doc = false

guide/book.toml

@@ -17,6 +17,9 @@ edit-url-template = "https://github.com/rust-lang/mdBook/edit/master/guide/{path
 editable = true
 line-numbers = true
 
+[output.html.code.hidelines]
+python = "~"
+
 [output.html.search]
 limit-results = 20
 use-boolean-and = true

guide/src/cli/init.md

@@ -67,4 +67,16 @@ mdbook init --title="my amazing book"
 Create a `.gitignore` file configured to ignore the `book` directory created when [building] a book. 
 If not supplied, an interactive prompt will ask whether it should be created.
 
+```bash
+mdbook init --ignore=none
+```
+
+```bash
+mdbook init --ignore=git
+```
+
 [building]: build.md
+
+#### --force
+
+Skip the prompts to create a `.gitignore` and for the title for the book.

guide/src/continuous-integration.md

@@ -21,7 +21,7 @@ A simple approach would be to use the popular `curl` CLI tool to download the ex
 
 ```sh
 mkdir bin
-curl -sSL https://github.com/rust-lang/mdBook/releases/download/v0.4.28/mdbook-v0.4.28-x86_64-unknown-linux-gnu.tar.gz | tar -xz --directory=bin
+curl -sSL https://github.com/rust-lang/mdBook/releases/download/v0.4.31/mdbook-v0.4.31-x86_64-unknown-linux-gnu.tar.gz | tar -xz --directory=bin
 bin/mdbook build
 ```
 

guide/src/format/configuration/preprocessors.md

@@ -35,7 +35,7 @@ For example, if you have a preprocessor called `mdbook-example`, then you can in
 With this table, mdBook will execute the `mdbook-example` preprocessor.
 
 This table can include additional key-value pairs that are specific to the preprocessor.
-For example, if our example prepocessor needed some extra configuration options:
+For example, if our example preprocessor needed some extra configuration options:
 
 ```toml
 [preprocessor.example]

guide/src/format/configuration/renderers.md

@@ -150,9 +150,9 @@ The following configuration options are available:
 - **edit-url-template:** Edit url template, when provided shows a
   "Suggest an edit" button (which looks like <i class="fa fa-edit"></i>) for directly jumping to editing the currently
   viewed page. For e.g. GitHub projects set this to
-  `https://github.com/<owner>/<repo>/edit/master/{path}` or for
+  `https://github.com/<owner>/<repo>/edit/<branch>/{path}` or for
   Bitbucket projects set it to
-  `https://bitbucket.org/<owner>/<repo>/src/master/{path}?mode=edit`
+  `https://bitbucket.org/<owner>/<repo>/src/<branch>/{path}?mode=edit`
   where {path} will be replaced with the full path of the file in the
   repository.
 - **input-404:** The name of the markdown file used for missing files.
@@ -182,7 +182,7 @@ page-break = true # insert page-break after each chapter
 
 - **enable:** Enable print support. When `false`, all print support will not be
   rendered. Defaults to `true`.
-- **page-break** Insert page breaks between chapters. Defaults to `true`.
+- **page-break:** Insert page breaks between chapters. Defaults to `true`.
 
 ### `[output.html.fold]`
 
@@ -218,11 +218,25 @@ runnable = true          # displays a run button for rust code
 - **copyable:** Display the copy button on code snippets. Defaults to `true`.
 - **copy-js:** Copy JavaScript files for the editor to the output directory.
   Defaults to `true`.
-- **line-numbers** Display line numbers on editable sections of code. Requires both `editable` and `copy-js` to be `true`. Defaults to `false`.
+- **line-numbers:** Display line numbers on editable sections of code. Requires both `editable` and `copy-js` to be `true`. Defaults to `false`.
-- **runnable** Displays a run button for rust code snippets. Changing this to `false` will disable the run in playground feature globally. Defaults to `true`.
+- **runnable:** Displays a run button for rust code snippets. Changing this to `false` will disable the run in playground feature globally. Defaults to `true`.
 
 [Ace]: https://ace.c9.io/
 
+### `[output.html.code]`
+
+The `[output.html.code]` table provides options for controlling code blocks.
+
+```toml
+[output.html.code]
+# A prefix string per language (one or more chars).
+# Any line starting with whitespace+prefix is hidden.
+hidelines = { python = "~" }
+```
+
+- **hidelines:** A table that defines how [hidden code lines](../mdbook.md#hiding-code-lines) work for each language.
+  The key is the language and the value is a string that will cause code lines starting with that prefix to be hidden.
+
 ### `[output.html.search]`
 
 The `[output.html.search]` table provides options for controlling the built-in text [search].

guide/src/format/markdown.md

@@ -124,7 +124,7 @@ mdBook has several extensions beyond the standard CommonMark specification.
 ### Strikethrough
 
 Text may be rendered with a horizontal line through the center by wrapping the
-text with two tilde characters on each side:
+text with one or two tilde characters on each side:
 
 ```text
 An example of ~~strikethrough text~~.
@@ -220,3 +220,16 @@ To enable it, see the [`output.html.curly-quotes`] config option.
 [tables]: https://github.github.com/gfm/#tables-extension-
 [task list extension]: https://github.github.com/gfm/#task-list-items-extension-
 [`output.html.curly-quotes`]: configuration/renderers.md#html-renderer-options
+
+### Heading attributes
+
+Headings can have a custom HTML ID and classes. This lets you maintain the same ID even if you change the heading's text, it also lets you add multiple classes in the heading.
+
+Example:
+```md
+# Example heading { #first .class1 .class2 }
+```
+
+This makes the level 1 heading with the content `Example heading`, ID `first`, and classes `class1` and `class2`. Note that the attributes should be space-separated.
+
+More information can be found in the [heading attrs spec page](https://github.com/raphlinus/pulldown-cmark/blob/master/specs/heading_attrs.txt).

guide/src/format/mdbook.md

@@ -2,11 +2,11 @@
 
 ## Hiding code lines
 
-There is a feature in mdBook that lets you hide code lines by prepending them
+There is a feature in mdBook that lets you hide code lines by prepending them with a specific prefix.
-with a `#` [like you would with Rustdoc][rustdoc-hide].
-This currently only works with Rust language code blocks.
 
-[rustdoc-hide]: https://doc.rust-lang.org/stable/rustdoc/documentation-tests.html#hiding-portions-of-the-example
+For the Rust language, you can use the `#` character as a prefix which will hide lines [like you would with Rustdoc][rustdoc-hide].
+
+[rustdoc-hide]: https://doc.rust-lang.org/stable/rustdoc/write-documentation/documentation-tests.html#hiding-portions-of-the-example
 
 ```bash
 # fn main() {
@@ -28,7 +28,47 @@ Will render as
 # }
 ```
 
-The code block has an eyeball icon (<i class="fa fa-eye"></i>) which will toggle the visibility of the hidden lines.
+When you tap or hover the mouse over the code block, there will be an eyeball icon (<i class="fa fa-eye"></i>) which will toggle the visibility of the hidden lines.
+
+By default, this only works for code examples that are annotated with `rust`.
+However, you can define custom prefixes for other languages by adding a new line-hiding prefix in your `book.toml` with the language name and prefix character(s):
+
+```toml
+[output.html.code.hidelines]
+python = "~"
+```
+
+The prefix will hide any lines that begin with the given prefix. With the python prefix shown above, this:
+
+```bash
+~hidden()
+nothidden():
+~    hidden()
+    ~hidden()
+    nothidden()
+```
+
+will render as
+
+```python
+~hidden()
+nothidden():
+~    hidden()
+    ~hidden()
+    nothidden()
+```
+
+This behavior can be overridden locally with a different prefix. This has the same effect as above:
+
+~~~markdown
+```python,hidelines=!!!
+!!!hidden()
+nothidden():
+!!!    hidden()
+    !!!hidden()
+    nothidden()
+```
+~~~
 
 ## Rust Playground
 

guide/src/format/theme/README.md

@@ -1,6 +1,6 @@
 # Theme
 
-The default renderer uses a [handlebars](http://handlebarsjs.com/) template to
+The default renderer uses a [handlebars](https://handlebarsjs.com) template to
 render your markdown files and comes with a default theme included in the mdBook
 binary.
 

guide/src/format/theme/syntax-highlighting.md

@@ -77,38 +77,6 @@ the `theme` folder of your book.
 
 Now your theme will be used instead of the default theme.
 
-## Hiding code lines
-
-There is a feature in mdBook that lets you hide code lines by prepending them
-with a `#`.
-
-
-```bash
-# fn main() {
-    let x = 5;
-    let y = 6;
-
-    println!("{}", x + y);
-# }
-```
-
-Will render as
-
-```rust
-# fn main() {
-    let x = 5;
-    let y = 7;
-
-    println!("{}", x + y);
-# }
-```
-
-**At the moment, this only works for code examples that are annotated with
-`rust`. Because it would collide with semantics of some programming languages.
-In the future, we want to make this configurable through the `book.toml` so that
-everyone can benefit from it.**
-
-
 ## Improve default theme
 
 If you think the default theme doesn't look quite right for a specific language,

guide/src/guide/installation.md

@@ -20,7 +20,7 @@ To make it easier to run, put the path to the binary into your `PATH`.
 
 To build the `mdbook` executable from source, you will first need to install Rust and Cargo.
 Follow the instructions on the [Rust installation page].
-mdBook currently requires at least Rust version 1.60.
+mdBook currently requires at least Rust version 1.65.
 
 Once you have installed Rust, the following command can be used to build and install mdBook:
 

src/book/book.rs

@@ -39,9 +39,7 @@ fn create_missing(src_dir: &Path, summary: &Summary) -> Result<()> {
         .chain(summary.suffix_chapters.iter())
         .collect();
 
-    while !items.is_empty() {
+    while let Some(next) = items.pop() {
-        let next = items.pop().expect("already checked");
-
         if let SummaryItem::Link(ref link) = *next {
             if let Some(ref location) = link.location {
                 let filename = src_dir.join(location);
@@ -277,7 +275,7 @@ fn load_chapter<P: AsRef<Path>>(
         }
 
         let stripped = location
-            .strip_prefix(&src_dir)
+            .strip_prefix(src_dir)
             .expect("Chapters are always inside a book");
 
         Chapter::new(&link.name, content, stripped, parent_names.clone())
@@ -317,7 +315,7 @@ impl<'a> Iterator for BookItems<'a> {
     fn next(&mut self) -> Option<Self::Item> {
         let item = self.items.pop_front();
 
-        if let Some(&BookItem::Chapter(ref ch)) = item {
+        if let Some(BookItem::Chapter(ch)) = item {
             // if we wanted a breadth-first iterator we'd `extend()` here
             for sub_item in ch.sub_items.iter().rev() {
                 self.items.push_front(sub_item);

src/book/init.rs

@@ -198,8 +198,7 @@ impl BookBuilder {
             writeln!(f, "- [Chapter 1](./chapter_1.md)")?;
 
             let chapter_1 = src_dir.join("chapter_1.md");
-            let mut f =
+            let mut f = File::create(chapter_1).with_context(|| "Unable to create chapter_1.md")?;
-                File::create(&chapter_1).with_context(|| "Unable to create chapter_1.md")?;
             writeln!(f, "# Chapter 1")?;
         } else {
             trace!("Existing summary found, no need to create stub files.");
@@ -212,10 +211,10 @@ impl BookBuilder {
         fs::create_dir_all(&self.root)?;
 
         let src = self.root.join(&self.config.book.src);
-        fs::create_dir_all(&src)?;
+        fs::create_dir_all(src)?;
 
         let build = self.root.join(&self.config.build.build_dir);
-        fs::create_dir_all(&build)?;
+        fs::create_dir_all(build)?;
 
         Ok(())
     }

src/book/mod.rs

@@ -99,7 +99,7 @@ impl MDBook {
         let root = book_root.into();
 
         let src_dir = root.join(&config.book.src);
-        let book = book::load_book(&src_dir, &config.build)?;
+        let book = book::load_book(src_dir, &config.build)?;
 
         let renderers = determine_renderers(&config);
         let preprocessors = determine_preprocessors(&config)?;
@@ -122,7 +122,7 @@ impl MDBook {
         let root = book_root.into();
 
         let src_dir = root.join(&config.book.src);
-        let book = book::load_book_from_disk(&summary, &src_dir)?;
+        let book = book::load_book_from_disk(&summary, src_dir)?;
 
         let renderers = determine_renderers(&config);
         let preprocessors = determine_preprocessors(&config)?;
@@ -309,7 +309,7 @@ impl MDBook {
                 info!("Testing chapter '{}': {:?}", ch.name, chapter_path);
 
                 // write preprocessed file to tempdir
-                let path = temp_dir.path().join(&chapter_path);
+                let path = temp_dir.path().join(chapter_path);
                 let mut tmpf = utils::fs::create_file(&path)?;
                 tmpf.write_all(ch.content.as_bytes())?;
 
@@ -319,13 +319,13 @@ impl MDBook {
                 if let Some(edition) = self.config.rust.edition {
                     match edition {
                         RustEdition::E2015 => {
-                            cmd.args(&["--edition", "2015"]);
+                            cmd.args(["--edition", "2015"]);
                         }
                         RustEdition::E2018 => {
-                            cmd.args(&["--edition", "2018"]);
+                            cmd.args(["--edition", "2018"]);
                         }
                         RustEdition::E2021 => {
-                            cmd.args(&["--edition", "2021"]);
+                            cmd.args(["--edition", "2021"]);
                         }
                     }
                 }

src/cmd/build.rs

@@ -16,7 +16,7 @@ pub fn make_subcommand() -> Command {
 // Build command implementation
 pub fn execute(args: &ArgMatches) -> Result<()> {
     let book_dir = get_book_dir(args);
-    let mut book = MDBook::load(&book_dir)?;
+    let mut book = MDBook::load(book_dir)?;
 
     if let Some(dest_dir) = args.get_one::<PathBuf>("dest-dir") {
         book.config.build.build_dir = dest_dir.into();

src/cmd/clean.rs

@@ -16,7 +16,7 @@ pub fn make_subcommand() -> Command {
 // Clean command implementation
 pub fn execute(args: &ArgMatches) -> mdbook::errors::Result<()> {
     let book_dir = get_book_dir(args);
-    let book = MDBook::load(&book_dir)?;
+    let book = MDBook::load(book_dir)?;
 
     let dir_to_remove = match args.get_one::<PathBuf>("dest-dir") {
         Some(dest_dir) => dest_dir.into(),

src/cmd/init.rs

@@ -56,7 +56,7 @@ pub fn execute(args: &ArgMatches) -> Result<()> {
             "git" => builder.create_gitignore(true),
             _ => builder.create_gitignore(false),
         };
-    } else {
+    } else if !args.get_flag("force") {
         println!("\nDo you want a .gitignore to be created? (y/n)");
         if confirm() {
             builder.create_gitignore(true);
@@ -65,6 +65,8 @@ pub fn execute(args: &ArgMatches) -> Result<()> {
 
     config.book.title = if args.contains_id("title") {
         args.get_one::<String>("title").map(String::from)
+    } else if args.get_flag("force") {
+        None
     } else {
         request_book_title()
     };
@@ -84,7 +86,7 @@ pub fn execute(args: &ArgMatches) -> Result<()> {
 /// Obtains author name from git config file by running the `git config` command.
 fn get_author_name() -> Option<String> {
     let output = Command::new("git")
-        .args(&["config", "--get", "user.name"])
+        .args(["config", "--get", "user.name"])
         .output()
         .ok()?;
 
@@ -114,5 +116,5 @@ fn confirm() -> bool {
     io::stdout().flush().unwrap();
     let mut s = String::new();
     io::stdin().read_line(&mut s).ok();
-    matches!(&*s.trim(), "Y" | "y" | "yes" | "Yes")
+    matches!(s.trim(), "Y" | "y" | "yes" | "Yes")
 }

src/cmd/serve.rs

@@ -48,7 +48,7 @@ pub fn make_subcommand() -> Command {
 // Serve command implementation
 pub fn execute(args: &ArgMatches) -> Result<()> {
     let book_dir = get_book_dir(args);
-    let mut book = MDBook::load(&book_dir)?;
+    let mut book = MDBook::load(book_dir)?;
 
     let port = args.get_one::<String>("port").unwrap();
     let hostname = args.get_one::<String>("hostname").unwrap();
@@ -102,7 +102,7 @@ pub fn execute(args: &ArgMatches) -> Result<()> {
         info!("Building book...");
 
         // FIXME: This area is really ugly because we need to re-set livereload :(
-        let result = MDBook::load(&book_dir).and_then(|mut b| {
+        let result = MDBook::load(book_dir).and_then(|mut b| {
             update_config(&mut b);
             b.build()
         });

src/cmd/test.rs

@@ -44,7 +44,7 @@ pub fn execute(args: &ArgMatches) -> Result<()> {
     let chapter: Option<&str> = args.get_one::<String>("chapter").map(|s| s.as_str());
 
     let book_dir = get_book_dir(args);
-    let mut book = MDBook::load(&book_dir)?;
+    let mut book = MDBook::load(book_dir)?;
 
     if let Some(dest_dir) = args.get_one::<PathBuf>("dest-dir") {
         book.config.build.build_dir = dest_dir.to_path_buf();

src/cmd/watch.rs

@@ -1,5 +1,6 @@
 use super::command_prelude::*;
 use crate::{get_book_dir, open};
+use ignore::gitignore::Gitignore;
 use mdbook::errors::Result;
 use mdbook::utils;
 use mdbook::MDBook;
@@ -20,7 +21,7 @@ pub fn make_subcommand() -> Command {
 // Watch command implementation
 pub fn execute(args: &ArgMatches) -> Result<()> {
     let book_dir = get_book_dir(args);
-    let mut book = MDBook::load(&book_dir)?;
+    let mut book = MDBook::load(book_dir)?;
 
     let update_config = |book: &mut MDBook| {
         if let Some(dest_dir) = args.get_one::<PathBuf>("dest-dir") {
@@ -41,7 +42,7 @@ pub fn execute(args: &ArgMatches) -> Result<()> {
 
     trigger_on_change(&book, |paths, book_dir| {
         info!("Files changed: {:?}\nBuilding book...\n", paths);
-        let result = MDBook::load(&book_dir).and_then(|mut b| {
+        let result = MDBook::load(book_dir).and_then(|mut b| {
             update_config(&mut b);
             b.build()
         });
@@ -62,14 +63,14 @@ fn remove_ignored_files(book_root: &Path, paths: &[PathBuf]) -> Vec<PathBuf> {
 
     match find_gitignore(book_root) {
         Some(gitignore_path) => {
-            match gitignore::File::new(gitignore_path.as_path()) {
+            let (ignore, err) = Gitignore::new(&gitignore_path);
-                Ok(exclusion_checker) => filter_ignored_files(exclusion_checker, paths),
+            if let Some(err) = err {
-                Err(_) => {
+                warn!(
-                    // We're unable to read the .gitignore file, so we'll silently allow everything.
+                    "error reading gitignore `{}`: {err}",
-                    // Please see discussion: https://github.com/rust-lang/mdBook/pull/1051
+                    gitignore_path.display()
-                    paths.iter().map(|path| path.to_path_buf()).collect()
+                );
-                }
             }
+            filter_ignored_files(ignore, paths)
         }
         None => {
             // There is no .gitignore file.
@@ -85,18 +86,13 @@ fn find_gitignore(book_root: &Path) -> Option<PathBuf> {
         .find(|p| p.exists())
 }
 
-fn filter_ignored_files(exclusion_checker: gitignore::File, paths: &[PathBuf]) -> Vec<PathBuf> {
+fn filter_ignored_files(ignore: Gitignore, paths: &[PathBuf]) -> Vec<PathBuf> {
     paths
         .iter()
-        .filter(|path| match exclusion_checker.is_excluded(path) {
+        .filter(|path| {
-            Ok(exclude) => !exclude,
+            !ignore
-            Err(error) => {
+                .matched_path_or_any_parents(path, path.is_dir())
-                warn!(
+                .is_ignore()
-                    "Unable to determine if {:?} is excluded: {:?}. Including it.",
-                    &path, error
-                );
-                true
-            }
         })
         .map(|path| path.to_path_buf())
         .collect()

src/config.rs

@@ -308,7 +308,7 @@ impl<'de> serde::Deserialize<'de> for Config {
             warn!("`description` under a table called `[book]`, move the `destination` entry");
             warn!("from `[output.html]`, renamed to `build-dir`, under a table called");
             warn!("`[build]`, and it should all work.");
-            warn!("Documentation: http://rust-lang.github.io/mdBook/format/config.html");
+            warn!("Documentation: https://rust-lang.github.io/mdBook/format/config.html");
             return Ok(Config::from_legacy(raw));
         }
 
@@ -504,6 +504,8 @@ pub struct HtmlConfig {
     /// Playground settings.
     #[serde(alias = "playpen")]
     pub playground: Playground,
+    /// Code settings.
+    pub code: Code,
     /// Print settings.
     pub print: Print,
     /// Don't render section labels.
@@ -556,6 +558,7 @@ impl Default for HtmlConfig {
             additional_js: Vec::new(),
             fold: Fold::default(),
             playground: Playground::default(),
+            code: Code::default(),
             print: Print::default(),
             no_section_label: false,
             search: None,
@@ -642,6 +645,22 @@ impl Default for Playground {
     }
 }
 
+/// Configuration for tweaking how the the HTML renderer handles code blocks.
+#[derive(Debug, Clone, PartialEq, Serialize, Deserialize)]
+#[serde(default, rename_all = "kebab-case")]
+pub struct Code {
+    /// A prefix string to hide lines per language (one or more chars).
+    pub hidelines: HashMap<String, String>,
+}
+
+impl Default for Code {
+    fn default() -> Code {
+        Code {
+            hidelines: HashMap::new(),
+        }
+    }
+}
+
 /// Configuration of the search functionality of the HTML renderer.
 #[derive(Debug, Clone, PartialEq, Serialize, Deserialize)]
 #[serde(default, rename_all = "kebab-case")]
@@ -703,7 +722,7 @@ trait Updateable<'de>: Serialize + Deserialize<'de> {
         let mut raw = Value::try_from(&self).expect("unreachable");
 
         if let Ok(value) = Value::try_from(value) {
-            let _ = raw.insert(key, value);
+            raw.insert(key, value);
         } else {
             return;
         }

src/preprocess/links.rs

@@ -93,7 +93,7 @@ where
     for link in find_links(s) {
         replaced.push_str(&s[previous_end_index..link.start_index]);
 
-        match link.render_with_path(&path, chapter_title) {
+        match link.render_with_path(path, chapter_title) {
             Ok(new_content) => {
                 if depth < MAX_LINK_NESTED_DEPTH {
                     if let Some(rel_path) = link.link_type.relative_path(path) {
@@ -327,7 +327,7 @@ impl<'a> Link<'a> {
         let base = base.as_ref();
         match self.link_type {
             // omit the escape char
-            LinkType::Escaped => Ok((&self.link_text[1..]).to_owned()),
+            LinkType::Escaped => Ok(self.link_text[1..].to_owned()),
             LinkType::Include(ref pat, ref range_or_anchor) => {
                 let target = base.join(pat);
 

src/renderer/html_handlebars/hbs_renderer.rs

@@ -1,5 +1,5 @@
 use crate::book::{Book, BookItem};
-use crate::config::{BookConfig, Config, HtmlConfig, Playground, RustEdition};
+use crate::config::{BookConfig, Code, Config, HtmlConfig, Playground, RustEdition};
 use crate::errors::*;
 use crate::renderer::html_handlebars::helpers;
 use crate::renderer::{RenderContext, Renderer};
@@ -99,7 +99,7 @@ impl HtmlHandlebars {
         ctx.data.insert("title".to_owned(), json!(title));
         ctx.data.insert(
             "path_to_root".to_owned(),
-            json!(utils::fs::path_to_root(&path)),
+            json!(utils::fs::path_to_root(path)),
         );
         if let Some(ref section) = ch.number {
             ctx.data
@@ -110,7 +110,12 @@ impl HtmlHandlebars {
         debug!("Render template");
         let rendered = ctx.handlebars.render("index", &ctx.data)?;
 
-        let rendered = self.post_process(rendered, &ctx.html_config.playground, ctx.edition);
+        let rendered = self.post_process(
+            rendered,
+            &ctx.html_config.playground,
+            &ctx.html_config.code,
+            ctx.edition,
+        );
 
         // Write to file
         debug!("Creating {}", filepath.display());
@@ -121,8 +126,12 @@ impl HtmlHandlebars {
             ctx.data.insert("path_to_root".to_owned(), json!(""));
             ctx.data.insert("is_index".to_owned(), json!(true));
             let rendered_index = ctx.handlebars.render("index", &ctx.data)?;
-            let rendered_index =
+            let rendered_index = self.post_process(
-                self.post_process(rendered_index, &ctx.html_config.playground, ctx.edition);
+                rendered_index,
+                &ctx.html_config.playground,
+                &ctx.html_config.code,
+                ctx.edition,
+            );
             debug!("Creating index.html from {}", ctx_path);
             utils::fs::write_file(&ctx.destination, "index.html", rendered_index.as_bytes())?;
         }
@@ -182,8 +191,12 @@ impl HtmlHandlebars {
         data_404.insert("title".to_owned(), json!(title));
         let rendered = handlebars.render("index", &data_404)?;
 
-        let rendered =
+        let rendered = self.post_process(
-            self.post_process(rendered, &html_config.playground, ctx.config.rust.edition);
+            rendered,
+            &html_config.playground,
+            &html_config.code,
+            ctx.config.rust.edition,
+        );
         let output_file = get_404_output_file(&html_config.input_404);
         utils::fs::write_file(destination, output_file, rendered.as_bytes())?;
         debug!("Creating 404.html ✓");
@@ -195,11 +208,13 @@ impl HtmlHandlebars {
         &self,
         rendered: String,
         playground_config: &Playground,
+        code_config: &Code,
         edition: Option<RustEdition>,
     ) -> String {
         let rendered = build_header_links(&rendered);
         let rendered = fix_code_blocks(&rendered);
         let rendered = add_playground_pre(&rendered, playground_config, edition);
+        let rendered = hide_lines(&rendered, code_config);
 
         rendered
     }
@@ -275,7 +290,8 @@ impl HtmlHandlebars {
             "FontAwesome/fonts/FontAwesome.ttf",
             theme::FONT_AWESOME_TTF,
         )?;
-        if html_config.copy_fonts {
+        // Don't copy the stock fonts if the user has specified their own fonts to use.
+        if html_config.copy_fonts && theme.fonts_css.is_none() {
             write_file(destination, "fonts/fonts.css", theme::fonts::CSS)?;
             for (file_name, contents) in theme::fonts::LICENSES.iter() {
                 write_file(destination, file_name, contents)?;
@@ -291,20 +307,13 @@ impl HtmlHandlebars {
         }
         if let Some(fonts_css) = &theme.fonts_css {
             if !fonts_css.is_empty() {
-                if html_config.copy_fonts {
+                write_file(destination, "fonts/fonts.css", fonts_css)?;
-                    warn!(
-                        "output.html.copy_fonts is deprecated.\n\
-                        Set copy_fonts=false and ensure the fonts you want are in \
-                        the `theme/fonts/` directory."
-                    );
-                }
-                write_file(destination, "fonts/fonts.css", &fonts_css)?;
             }
         }
         if !html_config.copy_fonts && theme.fonts_css.is_none() {
             warn!(
-                "output.html.copy_fonts is deprecated.\n\
+                "output.html.copy-fonts is deprecated.\n\
-                This book appears to have copy_fonts=false without a fonts.css file.\n\
+                This book appears to have copy-fonts=false in book.toml without a fonts.css file.\n\
                 Add an empty `theme/fonts/fonts.css` file to squelch this warning."
             );
         }
@@ -553,7 +562,7 @@ impl Renderer for HtmlHandlebars {
         // Print version
         let mut print_content = String::new();
 
-        fs::create_dir_all(&destination)
+        fs::create_dir_all(destination)
             .with_context(|| "Unexpected error when constructing destination path")?;
 
         let mut is_index = true;
@@ -589,8 +598,12 @@ impl Renderer for HtmlHandlebars {
             debug!("Render template");
             let rendered = handlebars.render("index", &data)?;
 
-            let rendered =
+            let rendered = self.post_process(
-                self.post_process(rendered, &html_config.playground, ctx.config.rust.edition);
+                rendered,
+                &html_config.playground,
+                &html_config.code,
+                ctx.config.rust.edition,
+            );
 
             utils::fs::write_file(destination, "print.html", rendered.as_bytes())?;
             debug!("Creating print.html ✓");
@@ -795,8 +808,10 @@ fn make_data(
 /// Goes through the rendered HTML, making sure all header tags have
 /// an anchor respectively so people can link to sections directly.
 fn build_header_links(html: &str) -> String {
-    static BUILD_HEADER_LINKS: Lazy<Regex> =
+    static BUILD_HEADER_LINKS: Lazy<Regex> = Lazy::new(|| {
-        Lazy::new(|| Regex::new(r"<h(\d)>(.*?)</h\d>").unwrap());
+        Regex::new(r#"<h(\d)(?: id="([^"]+)")?(?: class="([^"]+)")?>(.*?)</h\d>"#).unwrap()
+    });
+    static IGNORE_CLASS: &[&str] = &["menu-title"];
 
     let mut id_counter = HashMap::new();
 
@@ -806,7 +821,22 @@ fn build_header_links(html: &str) -> String {
                 .parse()
                 .expect("Regex should ensure we only ever get numbers here");
 
-            insert_link_into_header(level, &caps[2], &mut id_counter)
+            // Ignore .menu-title because now it's getting detected by the regex.
+            if let Some(classes) = caps.get(3) {
+                for class in classes.as_str().split(" ") {
+                    if IGNORE_CLASS.contains(&class) {
+                        return caps[0].to_string();
+                    }
+                }
+            }
+
+            insert_link_into_header(
+                level,
+                &caps[4],
+                caps.get(2).map(|x| x.as_str().to_string()),
+                caps.get(3).map(|x| x.as_str().to_string()),
+                &mut id_counter,
+            )
         })
         .into_owned()
 }
@@ -816,15 +846,21 @@ fn build_header_links(html: &str) -> String {
 fn insert_link_into_header(
     level: usize,
     content: &str,
+    id: Option<String>,
+    classes: Option<String>,
     id_counter: &mut HashMap<String, usize>,
 ) -> String {
-    let id = utils::unique_id_from_content(content, id_counter);
+    let id = id.unwrap_or_else(|| utils::unique_id_from_content(content, id_counter));
+    let classes = classes
+        .map(|s| format!(" class=\"{s}\""))
+        .unwrap_or_default();
 
     format!(
-        r##"<h{level} id="{id}"><a class="header" href="#{id}">{text}</a></h{level}>"##,
+        r##"<h{level} id="{id}"{classes}><a class="header" href="#{id}">{text}</a></h{level}>"##,
         level = level,
         id = id,
-        text = content
+        text = content,
+        classes = classes
     )
 }
 
@@ -856,67 +892,64 @@ fn fix_code_blocks(html: &str) -> String {
         .into_owned()
 }
 
+static CODE_BLOCK_RE: Lazy<Regex> =
+    Lazy::new(|| Regex::new(r##"((?s)<code[^>]?class="([^"]+)".*?>(.*?)</code>)"##).unwrap());
+
 fn add_playground_pre(
     html: &str,
     playground_config: &Playground,
     edition: Option<RustEdition>,
 ) -> String {
-    static ADD_PLAYGROUND_PRE: Lazy<Regex> =
+    CODE_BLOCK_RE
-        Lazy::new(|| Regex::new(r##"((?s)<code[^>]?class="([^"]+)".*?>(.*?)</code>)"##).unwrap());
-
-    ADD_PLAYGROUND_PRE
         .replace_all(html, |caps: &Captures<'_>| {
             let text = &caps[1];
             let classes = &caps[2];
             let code = &caps[3];
 
-            if classes.contains("language-rust") {
+            if classes.contains("language-rust")
-                if (!classes.contains("ignore")
+                && ((!classes.contains("ignore")
                     && !classes.contains("noplayground")
                     && !classes.contains("noplaypen")
                     && playground_config.runnable)
-                    || classes.contains("mdbook-runnable")
+                    || classes.contains("mdbook-runnable"))
-                {
+            {
-                    let contains_e2015 = classes.contains("edition2015");
+                let contains_e2015 = classes.contains("edition2015");
-                    let contains_e2018 = classes.contains("edition2018");
+                let contains_e2018 = classes.contains("edition2018");
-                    let contains_e2021 = classes.contains("edition2021");
+                let contains_e2021 = classes.contains("edition2021");
-                    let edition_class = if contains_e2015 || contains_e2018 || contains_e2021 {
+                let edition_class = if contains_e2015 || contains_e2018 || contains_e2021 {
-                        // the user forced edition, we should not overwrite it
+                    // the user forced edition, we should not overwrite it
-                        ""
+                    ""
-                    } else {
-                        match edition {
-                            Some(RustEdition::E2015) => " edition2015",
-                            Some(RustEdition::E2018) => " edition2018",
-                            Some(RustEdition::E2021) => " edition2021",
-                            None => "",
-                        }
-                    };
-
-                    // wrap the contents in an external pre block
-                    format!(
-                        "<pre class=\"playground\"><code class=\"{}{}\">{}</code></pre>",
-                        classes,
-                        edition_class,
-                        {
-                            let content: Cow<'_, str> = if playground_config.editable
-                                && classes.contains("editable")
-                                || text.contains("fn main")
-                                || text.contains("quick_main!")
-                            {
-                                code.into()
-                            } else {
-                                // we need to inject our own main
-                                let (attrs, code) = partition_source(code);
-
-                                format!("# #![allow(unused)]\n{}#fn main() {{\n{}#}}", attrs, code)
-                                    .into()
-                            };
-                            hide_lines(&content)
-                        }
-                    )
                 } else {
-                    format!("<code class=\"{}\">{}</code>", classes, hide_lines(code))
+                    match edition {
-                }
+                        Some(RustEdition::E2015) => " edition2015",
+                        Some(RustEdition::E2018) => " edition2018",
+                        Some(RustEdition::E2021) => " edition2021",
+                        None => "",
+                    }
+                };
+
+                // wrap the contents in an external pre block
+                format!(
+                    "<pre class=\"playground\"><code class=\"{}{}\">{}</code></pre>",
+                    classes,
+                    edition_class,
+                    {
+                        let content: Cow<'_, str> = if playground_config.editable
+                            && classes.contains("editable")
+                            || text.contains("fn main")
+                            || text.contains("quick_main!")
+                        {
+                            code.into()
+                        } else {
+                            // we need to inject our own main
+                            let (attrs, code) = partition_source(code);
+
+                            format!("# #![allow(unused)]\n{}#fn main() {{\n{}#}}", attrs, code)
+                                .into()
+                        };
+                        content
+                    }
+                )
             } else {
                 // not language-rust, so no-op
                 text.to_owned()
@@ -925,7 +958,50 @@ fn add_playground_pre(
         .into_owned()
 }
 
-fn hide_lines(content: &str) -> String {
+/// Modifies all `<code>` blocks to convert "hidden" lines and to wrap them in
+/// a `<span class="boring">`.
+fn hide_lines(html: &str, code_config: &Code) -> String {
+    let language_regex = Regex::new(r"\blanguage-(\w+)\b").unwrap();
+    let hidelines_regex = Regex::new(r"\bhidelines=(\S+)").unwrap();
+    CODE_BLOCK_RE
+        .replace_all(html, |caps: &Captures<'_>| {
+            let text = &caps[1];
+            let classes = &caps[2];
+            let code = &caps[3];
+
+            if classes.contains("language-rust") {
+                format!(
+                    "<code class=\"{}\">{}</code>",
+                    classes,
+                    hide_lines_rust(code)
+                )
+            } else {
+                // First try to get the prefix from the code block
+                let hidelines_capture = hidelines_regex.captures(classes);
+                let hidelines_prefix = match &hidelines_capture {
+                    Some(capture) => Some(&capture[1]),
+                    None => {
+                        // Then look up the prefix by language
+                        language_regex.captures(classes).and_then(|capture| {
+                            code_config.hidelines.get(&capture[1]).map(|p| p.as_str())
+                        })
+                    }
+                };
+
+                match hidelines_prefix {
+                    Some(prefix) => format!(
+                        "<code class=\"{}\">{}</code>",
+                        classes,
+                        hide_lines_with_prefix(code, prefix)
+                    ),
+                    None => text.to_owned(),
+                }
+            }
+        })
+        .into_owned()
+}
+
+fn hide_lines_rust(content: &str) -> String {
     static BORING_LINES_REGEX: Lazy<Regex> = Lazy::new(|| Regex::new(r"^(\s*)#(.?)(.*)$").unwrap());
 
     let mut result = String::with_capacity(content.len());
@@ -958,6 +1034,26 @@ fn hide_lines(content: &str) -> String {
     result
 }
 
+fn hide_lines_with_prefix(content: &str, prefix: &str) -> String {
+    let mut result = String::with_capacity(content.len());
+    for line in content.lines() {
+        if line.trim_start().starts_with(prefix) {
+            let pos = line.find(prefix).unwrap();
+            let (ws, rest) = (&line[..pos], &line[pos + prefix.len()..]);
+
+            result += "<span class=\"boring\">";
+            result += ws;
+            result += rest;
+            result += "\n";
+            result += "</span>";
+            continue;
+        }
+        result += line;
+        result += "\n";
+    }
+    result
+}
+
 fn partition_source(s: &str) -> (String, String) {
     let mut after_header = false;
     let mut before = String::new();
@@ -993,6 +1089,7 @@ struct RenderItemContext<'a> {
 #[cfg(test)]
 mod tests {
     use super::*;
+    use pretty_assertions::assert_eq;
 
     #[test]
     fn original_build_header_links() {
@@ -1021,6 +1118,21 @@ mod tests {
                 "<h1>Foo</h1><h3>Foo</h3>",
                 r##"<h1 id="foo"><a class="header" href="#foo">Foo</a></h1><h3 id="foo-1"><a class="header" href="#foo-1">Foo</a></h3>"##,
             ),
+            // id only
+            (
+                r##"<h1 id="foobar">Foo</h1>"##,
+                r##"<h1 id="foobar"><a class="header" href="#foobar">Foo</a></h1>"##,
+            ),
+            // class only
+            (
+                r##"<h1 class="class1 class2">Foo</h1>"##,
+                r##"<h1 id="foo" class="class1 class2"><a class="header" href="#foo">Foo</a></h1>"##,
+            ),
+            // both id and class
+            (
+                r##"<h1 id="foobar" class="class1 class2">Foo</h1>"##,
+                r##"<h1 id="foobar" class="class1 class2"><a class="header" href="#foobar">Foo</a></h1>"##,
+            ),
         ];
 
         for (src, should_be) in inputs {
@@ -1033,17 +1145,17 @@ mod tests {
     fn add_playground() {
         let inputs = [
           ("<code class=\"language-rust\">x()</code>",
-           "<pre class=\"playground\"><code class=\"language-rust\"><span class=\"boring\">#![allow(unused)]\n</span><span class=\"boring\">fn main() {\n</span>x()\n<span class=\"boring\">}</span></code></pre>"),
+           "<pre class=\"playground\"><code class=\"language-rust\"># #![allow(unused)]\n#fn main() {\nx()\n#}</code></pre>"),
           ("<code class=\"language-rust\">fn main() {}</code>",
            "<pre class=\"playground\"><code class=\"language-rust\">fn main() {}</code></pre>"),
           ("<code class=\"language-rust editable\">let s = \"foo\n # bar\n\";</code>",
-           "<pre class=\"playground\"><code class=\"language-rust editable\">let s = \"foo\n<span class=\"boring\"> bar\n</span>\";</code></pre>"),
-          ("<code class=\"language-rust editable\">let s = \"foo\n ## bar\n\";</code>",
            "<pre class=\"playground\"><code class=\"language-rust editable\">let s = \"foo\n # bar\n\";</code></pre>"),
+          ("<code class=\"language-rust editable\">let s = \"foo\n ## bar\n\";</code>",
+           "<pre class=\"playground\"><code class=\"language-rust editable\">let s = \"foo\n ## bar\n\";</code></pre>"),
           ("<code class=\"language-rust editable\">let s = \"foo\n # bar\n#\n\";</code>",
-           "<pre class=\"playground\"><code class=\"language-rust editable\">let s = \"foo\n<span class=\"boring\"> bar\n</span><span class=\"boring\">\n</span>\";</code></pre>"),
+           "<pre class=\"playground\"><code class=\"language-rust editable\">let s = \"foo\n # bar\n#\n\";</code></pre>"),
           ("<code class=\"language-rust ignore\">let s = \"foo\n # bar\n\";</code>",
-           "<code class=\"language-rust ignore\">let s = \"foo\n<span class=\"boring\"> bar\n</span>\";</code>"),
+           "<code class=\"language-rust ignore\">let s = \"foo\n # bar\n\";</code>"),
           ("<code class=\"language-rust editable\">#![no_std]\nlet s = \"foo\";\n #[some_attr]</code>",
            "<pre class=\"playground\"><code class=\"language-rust editable\">#![no_std]\nlet s = \"foo\";\n #[some_attr]</code></pre>"),
         ];
@@ -1063,7 +1175,7 @@ mod tests {
     fn add_playground_edition2015() {
         let inputs = [
           ("<code class=\"language-rust\">x()</code>",
-           "<pre class=\"playground\"><code class=\"language-rust edition2015\"><span class=\"boring\">#![allow(unused)]\n</span><span class=\"boring\">fn main() {\n</span>x()\n<span class=\"boring\">}</span></code></pre>"),
+           "<pre class=\"playground\"><code class=\"language-rust edition2015\"># #![allow(unused)]\n#fn main() {\nx()\n#}</code></pre>"),
           ("<code class=\"language-rust\">fn main() {}</code>",
            "<pre class=\"playground\"><code class=\"language-rust edition2015\">fn main() {}</code></pre>"),
           ("<code class=\"language-rust edition2015\">fn main() {}</code>",
@@ -1087,7 +1199,7 @@ mod tests {
     fn add_playground_edition2018() {
         let inputs = [
           ("<code class=\"language-rust\">x()</code>",
-           "<pre class=\"playground\"><code class=\"language-rust edition2018\"><span class=\"boring\">#![allow(unused)]\n</span><span class=\"boring\">fn main() {\n</span>x()\n<span class=\"boring\">}</span></code></pre>"),
+           "<pre class=\"playground\"><code class=\"language-rust edition2018\"># #![allow(unused)]\n#fn main() {\nx()\n#}</code></pre>"),
           ("<code class=\"language-rust\">fn main() {}</code>",
            "<pre class=\"playground\"><code class=\"language-rust edition2018\">fn main() {}</code></pre>"),
           ("<code class=\"language-rust edition2015\">fn main() {}</code>",
@@ -1111,7 +1223,7 @@ mod tests {
     fn add_playground_edition2021() {
         let inputs = [
             ("<code class=\"language-rust\">x()</code>",
-             "<pre class=\"playground\"><code class=\"language-rust edition2021\"><span class=\"boring\">#![allow(unused)]\n</span><span class=\"boring\">fn main() {\n</span>x()\n<span class=\"boring\">}</span></code></pre>"),
+             "<pre class=\"playground\"><code class=\"language-rust edition2021\"># #![allow(unused)]\n#fn main() {\nx()\n#}</code></pre>"),
             ("<code class=\"language-rust\">fn main() {}</code>",
              "<pre class=\"playground\"><code class=\"language-rust edition2021\">fn main() {}</code></pre>"),
             ("<code class=\"language-rust edition2015\">fn main() {}</code>",
@@ -1131,4 +1243,60 @@ mod tests {
             assert_eq!(&*got, *should_be);
         }
     }
+
+    #[test]
+    fn hide_lines_language_rust() {
+        let inputs = [
+          (
+           "<pre class=\"playground\"><code class=\"language-rust\">\n# #![allow(unused)]\n#fn main() {\nx()\n#}</code></pre>",
+           "<pre class=\"playground\"><code class=\"language-rust\">\n<span class=\"boring\">#![allow(unused)]\n</span><span class=\"boring\">fn main() {\n</span>x()\n<span class=\"boring\">}</span></code></pre>",),
+          (
+           "<pre class=\"playground\"><code class=\"language-rust\">fn main() {}</code></pre>",
+           "<pre class=\"playground\"><code class=\"language-rust\">fn main() {}</code></pre>",),
+          (
+           "<pre class=\"playground\"><code class=\"language-rust editable\">let s = \"foo\n # bar\n\";</code></pre>",
+           "<pre class=\"playground\"><code class=\"language-rust editable\">let s = \"foo\n<span class=\"boring\"> bar\n</span>\";</code></pre>",),
+          (
+           "<pre class=\"playground\"><code class=\"language-rust editable\">let s = \"foo\n ## bar\n\";</code></pre>",
+           "<pre class=\"playground\"><code class=\"language-rust editable\">let s = \"foo\n # bar\n\";</code></pre>",),
+          (
+           "<pre class=\"playground\"><code class=\"language-rust editable\">let s = \"foo\n # bar\n#\n\";</code></pre>",
+           "<pre class=\"playground\"><code class=\"language-rust editable\">let s = \"foo\n<span class=\"boring\"> bar\n</span><span class=\"boring\">\n</span>\";</code></pre>",),
+          (
+           "<code class=\"language-rust ignore\">let s = \"foo\n # bar\n\";</code>",
+           "<code class=\"language-rust ignore\">let s = \"foo\n<span class=\"boring\"> bar\n</span>\";</code>",),
+          (
+           "<pre class=\"playground\"><code class=\"language-rust editable\">#![no_std]\nlet s = \"foo\";\n #[some_attr]</code></pre>",
+           "<pre class=\"playground\"><code class=\"language-rust editable\">#![no_std]\nlet s = \"foo\";\n #[some_attr]</code></pre>",),
+        ];
+        for (src, should_be) in &inputs {
+            let got = hide_lines(src, &Code::default());
+            assert_eq!(&*got, *should_be);
+        }
+    }
+
+    #[test]
+    fn hide_lines_language_other() {
+        let inputs = [
+          (
+           "<code class=\"language-python\">~hidden()\nnothidden():\n~    hidden()\n    ~hidden()\n    nothidden()</code>",
+           "<code class=\"language-python\"><span class=\"boring\">hidden()\n</span>nothidden():\n<span class=\"boring\">    hidden()\n</span><span class=\"boring\">    hidden()\n</span>    nothidden()\n</code>",),
+           (
+            "<code class=\"language-python hidelines=!!!\">!!!hidden()\nnothidden():\n!!!    hidden()\n    !!!hidden()\n    nothidden()</code>",
+            "<code class=\"language-python hidelines=!!!\"><span class=\"boring\">hidden()\n</span>nothidden():\n<span class=\"boring\">    hidden()\n</span><span class=\"boring\">    hidden()\n</span>    nothidden()\n</code>",),
+        ];
+        for (src, should_be) in &inputs {
+            let got = hide_lines(
+                src,
+                &Code {
+                    hidelines: {
+                        let mut map = HashMap::new();
+                        map.insert("python".to_string(), "~".to_string());
+                        map
+                    },
+                },
+            );
+            assert_eq!(&*got, *should_be);
+        }
+    }
 }

src/renderer/html_handlebars/helpers/navigation.rs

@@ -127,7 +127,7 @@ fn render(
 
     context.insert(
         "path_to_root".to_owned(),
-        json!(utils::fs::path_to_root(&base_path)),
+        json!(utils::fs::path_to_root(base_path)),
     );
 
     chapter

src/renderer/html_handlebars/search.rs

@@ -138,9 +138,11 @@ fn render_item(
 
                 in_heading = true;
             }
-            Event::End(Tag::Heading(i, ..)) if i as u32 <= max_section_depth => {
+            Event::End(Tag::Heading(i, id, _classes)) if i as u32 <= max_section_depth => {
                 in_heading = false;
-                section_id = Some(utils::unique_id_from_content(&heading, &mut id_counter));
+                section_id = id
+                    .map(|id| id.to_string())
+                    .or_else(|| Some(utils::unique_id_from_content(&heading, &mut id_counter)));
                 breadcrumbs.push(heading.clone());
             }
             Event::Start(Tag::FootnoteDefinition(name)) => {

src/renderer/markdown_renderer.rs

@@ -37,14 +37,14 @@ impl Renderer for MarkdownRenderer {
                 if !ch.is_draft_chapter() {
                     utils::fs::write_file(
                         &ctx.destination,
-                        &ch.path.as_ref().expect("Checked path exists before"),
+                        ch.path.as_ref().expect("Checked path exists before"),
                         ch.content.as_bytes(),
                     )?;
                 }
             }
         }
 
-        fs::create_dir_all(&destination)
+        fs::create_dir_all(destination)
             .with_context(|| "Unexpected error when constructing destination path")?;
 
         Ok(())

src/theme/book.js

@@ -68,7 +68,7 @@ function playground_text(playground, hidden = true) {
     }
 
     // updates the visibility of play button based on `no_run` class and
-    // used crates vs ones available on http://play.rust-lang.org
+    // used crates vs ones available on https://play.rust-lang.org
     function update_play_button(pre_block, playground_crates) {
         var play_button = pre_block.querySelector(".play-button");
 
@@ -179,7 +179,7 @@ function playground_text(playground, hidden = true) {
     // even if highlighting doesn't apply
     code_nodes.forEach(function (block) { block.classList.add('hljs'); });
 
-    Array.from(document.querySelectorAll("code.language-rust")).forEach(function (block) {
+    Array.from(document.querySelectorAll("code.hljs")).forEach(function (block) {
 
         var lines = Array.from(block.querySelectorAll('.boring'));
         // If no lines were hidden, return
@@ -551,13 +551,6 @@ function playground_text(playground, hidden = true) {
             firstContact = null;
         }
     }, { passive: true });
-
-    // Scroll sidebar to current active section
-    var activeSection = document.getElementById("sidebar").querySelector(".active");
-    if (activeSection) {
-        // https://developer.mozilla.org/en-US/docs/Web/API/Element/scrollIntoView
-        activeSection.scrollIntoView({ block: 'center' });
-    }
 })();
 
 (function chapterNavigation() {
@@ -676,13 +669,14 @@ function playground_text(playground, hidden = true) {
         }, { passive: true });
     })();
     (function controllBorder() {
-        menu.classList.remove('bordered');
+        function updateBorder() {
-        document.addEventListener('scroll', function () {
             if (menu.offsetTop === 0) {
                 menu.classList.remove('bordered');
             } else {
                 menu.classList.add('bordered');
             }
-        }, { passive: true });
+        }
+        updateBorder();
+        document.addEventListener('scroll', updateBorder, { passive: true });
     })();
 })();

src/theme/index.hbs

@@ -110,12 +110,34 @@
             <div id="sidebar-resize-handle" class="sidebar-resize-handle"></div>
         </nav>
 
+        <!-- Track and set sidebar scroll position -->
+        <script>
+            var sidebarScrollbox = document.querySelector('#sidebar .sidebar-scrollbox');
+            sidebarScrollbox.addEventListener('click', function(e) {
+                if (e.target.tagName === 'A') {
+                    sessionStorage.setItem('sidebar-scroll', sidebarScrollbox.scrollTop);
+                }
+            }, { passive: true });
+            var sidebarScrollTop = sessionStorage.getItem('sidebar-scroll');
+            sessionStorage.removeItem('sidebar-scroll');
+            if (sidebarScrollTop) {
+                // preserve sidebar scroll position when navigating via links within sidebar
+                sidebarScrollbox.scrollTop = sidebarScrollTop;
+            } else {
+                // scroll sidebar to current active section when navigating via "next/previous chapter" buttons
+                var activeSection = document.querySelector('#sidebar .active');
+                if (activeSection) {
+                    activeSection.scrollIntoView({ block: 'center' });
+                }
+            }
+        </script>
+
         <div id="page-wrapper" class="page-wrapper">
 
             <div class="page">
                 {{> header}}
                 <div id="menu-bar-hover-placeholder"></div>
-                <div id="menu-bar" class="menu-bar sticky bordered">
+                <div id="menu-bar" class="menu-bar sticky">
                     <div class="left-buttons">
                         <button id="sidebar-toggle" class="icon-button" type="button" title="Toggle Table of Contents" aria-label="Toggle Table of Contents" aria-controls="sidebar">
                             <i class="fa fa-bars"></i>

src/theme/tomorrow-night.css

@@ -1,7 +1,7 @@
 /* Tomorrow Night Theme */
-/* http://jmblog.github.com/color-themes-for-google-code-highlightjs */
+/* https://github.com/jmblog/color-themes-for-highlightjs */
 /* Original theme - https://github.com/chriskempson/tomorrow-theme */
-/* http://jmblog.github.com/color-themes-for-google-code-highlightjs */
+/* https://github.com/jmblog/color-themes-for-highlightjs */
 
 /* Tomorrow Comment */
 .hljs-comment {

src/utils/fs.rs

@@ -210,39 +210,36 @@ mod tests {
         };
 
         // Create a couple of files
-        if let Err(err) = fs::File::create(&tmp.path().join("file.txt")) {
+        if let Err(err) = fs::File::create(tmp.path().join("file.txt")) {
             panic!("Could not create file.txt: {}", err);
         }
-        if let Err(err) = fs::File::create(&tmp.path().join("file.md")) {
+        if let Err(err) = fs::File::create(tmp.path().join("file.md")) {
             panic!("Could not create file.md: {}", err);
         }
-        if let Err(err) = fs::File::create(&tmp.path().join("file.png")) {
+        if let Err(err) = fs::File::create(tmp.path().join("file.png")) {
             panic!("Could not create file.png: {}", err);
         }
-        if let Err(err) = fs::create_dir(&tmp.path().join("sub_dir")) {
+        if let Err(err) = fs::create_dir(tmp.path().join("sub_dir")) {
             panic!("Could not create sub_dir: {}", err);
         }
-        if let Err(err) = fs::File::create(&tmp.path().join("sub_dir/file.png")) {
+        if let Err(err) = fs::File::create(tmp.path().join("sub_dir/file.png")) {
             panic!("Could not create sub_dir/file.png: {}", err);
         }
-        if let Err(err) = fs::create_dir(&tmp.path().join("sub_dir_exists")) {
+        if let Err(err) = fs::create_dir(tmp.path().join("sub_dir_exists")) {
             panic!("Could not create sub_dir_exists: {}", err);
         }
-        if let Err(err) = fs::File::create(&tmp.path().join("sub_dir_exists/file.txt")) {
+        if let Err(err) = fs::File::create(tmp.path().join("sub_dir_exists/file.txt")) {
             panic!("Could not create sub_dir_exists/file.txt: {}", err);
         }
-        if let Err(err) = symlink(
+        if let Err(err) = symlink(tmp.path().join("file.png"), tmp.path().join("symlink.png")) {
-            &tmp.path().join("file.png"),
-            &tmp.path().join("symlink.png"),
-        ) {
             panic!("Could not symlink file.png: {}", err);
         }
 
         // Create output dir
-        if let Err(err) = fs::create_dir(&tmp.path().join("output")) {
+        if let Err(err) = fs::create_dir(tmp.path().join("output")) {
             panic!("Could not create output: {}", err);
         }
-        if let Err(err) = fs::create_dir(&tmp.path().join("output/sub_dir_exists")) {
+        if let Err(err) = fs::create_dir(tmp.path().join("output/sub_dir_exists")) {
             panic!("Could not create output/sub_dir_exists: {}", err);
         }
 
@@ -253,22 +250,22 @@ mod tests {
         }
 
         // Check if the correct files where created
-        if !(&tmp.path().join("output/file.txt")).exists() {
+        if !tmp.path().join("output/file.txt").exists() {
             panic!("output/file.txt should exist")
         }
-        if (&tmp.path().join("output/file.md")).exists() {
+        if tmp.path().join("output/file.md").exists() {
             panic!("output/file.md should not exist")
         }
-        if !(&tmp.path().join("output/file.png")).exists() {
+        if !tmp.path().join("output/file.png").exists() {
             panic!("output/file.png should exist")
         }
-        if !(&tmp.path().join("output/sub_dir/file.png")).exists() {
+        if !tmp.path().join("output/sub_dir/file.png").exists() {
             panic!("output/sub_dir/file.png should exist")
         }
-        if !(&tmp.path().join("output/sub_dir_exists/file.txt")).exists() {
+        if !tmp.path().join("output/sub_dir_exists/file.txt").exists() {
             panic!("output/sub_dir/file.png should exist")
         }
-        if !(&tmp.path().join("output/symlink.png")).exists() {
+        if !tmp.path().join("output/symlink.png").exists() {
             panic!("output/symlink.png should exist")
         }
     }

src/utils/mod.rs

@@ -183,6 +183,7 @@ pub fn new_cmark_parser(text: &str, curly_quotes: bool) -> Parser<'_, '_> {
     opts.insert(Options::ENABLE_FOOTNOTES);
     opts.insert(Options::ENABLE_STRIKETHROUGH);
     opts.insert(Options::ENABLE_TASKLISTS);
+    opts.insert(Options::ENABLE_HEADING_ATTRIBUTES);
     if curly_quotes {
         opts.insert(Options::ENABLE_SMART_PUNCTUATION);
     }

test_book/src/individual/heading.md

@@ -13,3 +13,9 @@
 ##### Really Small Heading
 
 ###### Is it even a heading anymore - heading
+
+## Custom id {#example-id}
+
+## Custom class {.class1 .class2}
+
+## Both id and class {#example-id2 .class1 .class2}

test_book/src/individual/image.md

@@ -4,19 +4,19 @@ For copyright and trademark information on these images, please check [rust-artw
 
 ## A 16x16 image
 
-![16x16 rust-lang logo](http://rust-lang.org/logos/rust-logo-16x16.png)
+![16x16 rust-lang logo](https://rust-lang.org/logos/rust-logo-16x16.png)
 
 ## A 32x32 image
 
-![32x32 rust-lang logo](http://rust-lang.org/logos/rust-logo-32x32-blk.png)
+![32x32 rust-lang logo](https://rust-lang.org/logos/rust-logo-32x32-blk.png)
 
 ## A 256x256 image
 
-![256x256 rust-lang logo](http://rust-lang.org/logos/rust-logo-256x256.png)
+![256x256 rust-lang logo](https://rust-lang.org/logos/rust-logo-256x256.png)
 
 ## A 512x512 image
 
-![512x512 rust-lang logo](http://rust-lang.org/logos/rust-logo-512x512-blk.png)
+![512x512 rust-lang logo](https://rust-lang.org/logos/rust-logo-512x512-blk.png)
 
 ## A large image
 

test_book/src/individual/mixed.md

@@ -31,7 +31,7 @@ fn main(){
 
 A random image sprinkled in between
 
-![16x16 rust-lang logo](http://rust-lang.org/logos/rust-logo-16x16.png)
+![16x16 rust-lang logo](https://rust-lang.org/logos/rust-logo-16x16.png)
 
 ---
 

test_book/src/individual/strikethrough.md

@@ -1,5 +1,7 @@
 # Strikethrough
 
+~Single strike~
+
 ~~This is Striked~~
 
 ~~This is **strong**, _italic_ , **_both_** and striked~~

test_book/src/languages/highlight.md

@@ -57,7 +57,7 @@ _start:
 
 ## bash
 
-```
+```bash
 #!/bin/bash
 
 ###### CONFIG

tests/alternative_backends.rs

@@ -90,7 +90,7 @@ fn relative_command_path() {
             .set("output.html", toml::value::Table::new())
             .unwrap();
         config.set("output.myrenderer.command", cmd_path).unwrap();
-        let md = MDBook::init(&temp.path())
+        let md = MDBook::init(temp.path())
             .with_config(config)
             .build()
             .unwrap();

tests/cli/init.rs

@@ -0,0 +1,24 @@
+use crate::cli::cmd::mdbook_cmd;
+use crate::dummy_book::DummyBook;
+
+use mdbook::config::Config;
+
+/// Run `mdbook init` with `--force` to skip the confirmation prompts
+#[test]
+fn base_mdbook_init_can_skip_confirmation_prompts() {
+    let temp = DummyBook::new().build().unwrap();
+
+    // doesn't exist before
+    assert!(!temp.path().join("book").exists());
+
+    let mut cmd = mdbook_cmd();
+    cmd.args(["init", "--force"]).current_dir(temp.path());
+    cmd.assert()
+        .success()
+        .stdout(predicates::str::contains("\nAll done, no errors...\n"));
+
+    let config = Config::from_disk(temp.path().join("book.toml")).unwrap();
+    assert_eq!(config.book.title, None);
+
+    assert!(!temp.path().join(".gitignore").exists());
+}

tests/cli/mod.rs

@@ -1,3 +1,4 @@
 mod build;
 mod cmd;
+mod init;
 mod test;

tests/dummy_book/mod.rs

@@ -112,12 +112,12 @@ fn recursive_copy<A: AsRef<Path>, B: AsRef<Path>>(from: A, to: B) -> Result<()>
     let from = from.as_ref();
     let to = to.as_ref();
 
-    for entry in WalkDir::new(&from) {
+    for entry in WalkDir::new(from) {
         let entry = entry.with_context(|| "Unable to inspect directory entry")?;
 
         let original_location = entry.path();
         let relative = original_location
-            .strip_prefix(&from)
+            .strip_prefix(from)
             .expect("`original_location` is inside the `from` directory");
         let new_location = to.join(relative);
 
@@ -126,7 +126,7 @@ fn recursive_copy<A: AsRef<Path>, B: AsRef<Path>>(from: A, to: B) -> Result<()>
                 fs::create_dir_all(parent).with_context(|| "Couldn't create directory")?;
             }
 
-            fs::copy(&original_location, &new_location)
+            fs::copy(original_location, &new_location)
                 .with_context(|| "Unable to copy file contents")?;
         }
     }

tests/dummy_book/src/SUMMARY.md

@@ -14,6 +14,7 @@
     - [Unicode](first/unicode.md)
     - [No Headers](first/no-headers.md)
     - [Duplicate Headers](first/duplicate-headers.md)
+    - [Heading Attributes](first/heading-attributes.md)
 - [Second Chapter](second.md)
     - [Nested Chapter](second/nested.md)
 

tests/dummy_book/src/first/heading-attributes.md

@@ -0,0 +1,5 @@
+# Heading Attributes {#attrs}
+
+## Heading with classes {.class1 .class2}
+
+## Heading with id and classes {#both .class1 .class2}

tests/rendered_output.rs

@@ -35,6 +35,7 @@ const TOC_SECOND_LEVEL: &[&str] = &[
     "1.5. Unicode",
     "1.6. No Headers",
     "1.7. Duplicate Headers",
+    "1.8. Heading Attributes",
     "2.1. Nested Chapter",
 ];
 
@@ -275,7 +276,7 @@ fn root_index_html() -> Result<Document> {
         .with_context(|| "Book building failed")?;
 
     let index_page = temp.path().join("book").join("index.html");
-    let html = fs::read_to_string(&index_page).with_context(|| "Unable to read index.html")?;
+    let html = fs::read_to_string(index_page).with_context(|| "Unable to read index.html")?;
 
     Ok(Document::from(html.as_str()))
 }
@@ -412,7 +413,7 @@ fn recursive_includes_are_capped() {
     let content = &["Around the world, around the world
 Around the world, around the world
 Around the world, around the world"];
-    assert_contains_strings(&recursive, content);
+    assert_contains_strings(recursive, content);
 }
 
 #[test]
@@ -462,7 +463,7 @@ fn by_default_mdbook_use_index_preprocessor_to_convert_readme_to_index() {
 
     let second_index = temp.path().join("book").join("second").join("index.html");
     let unexpected_strings = vec!["Second README"];
-    assert_doesnt_contain_strings(&second_index, &unexpected_strings);
+    assert_doesnt_contain_strings(second_index, &unexpected_strings);
 }
 
 #[test]
@@ -628,10 +629,8 @@ fn edit_url_has_configured_src_dir_edit_url() {
 }
 
 fn remove_absolute_components(path: &Path) -> impl Iterator<Item = Component> + '_ {
-    path.components().skip_while(|c| match c {
+    path.components()
-        Component::Prefix(_) | Component::RootDir => true,
+        .skip_while(|c| matches!(c, Component::Prefix(_) | Component::RootDir))
-        _ => false,
-    })
 }
 
 /// Checks formatting of summary names with inline elements.
@@ -756,6 +755,7 @@ mod search {
         let no_headers = get_doc_ref("first/no-headers.html");
         let duplicate_headers_1 = get_doc_ref("first/duplicate-headers.html#header-text-1");
         let conclusion = get_doc_ref("conclusion.html#conclusion");
+        let heading_attrs = get_doc_ref("first/heading-attributes.html#both");
 
         let bodyidx = &index["index"]["index"]["body"]["root"];
         let textidx = &bodyidx["t"]["e"]["x"]["t"];
@@ -768,7 +768,7 @@ mod search {
         assert_eq!(docs[&some_section]["body"], "");
         assert_eq!(
             docs[&summary]["body"],
-            "Dummy Book Introduction First Chapter Nested Chapter Includes Recursive Markdown Unicode No Headers Duplicate Headers Second Chapter Nested Chapter Conclusion"
+            "Dummy Book Introduction First Chapter Nested Chapter Includes Recursive Markdown Unicode No Headers Duplicate Headers Heading Attributes Second Chapter Nested Chapter Conclusion"
         );
         assert_eq!(
             docs[&summary]["breadcrumbs"],
@@ -787,6 +787,10 @@ mod search {
             docs[&no_headers]["body"],
             "Capybara capybara capybara. Capybara capybara capybara. ThisLongWordIsIncludedSoWeCanCheckThatSufficientlyLongWordsAreOmittedFromTheSearchIndex."
         );
+        assert_eq!(
+            docs[&heading_attrs]["breadcrumbs"],
+            "First Chapter » Heading Attributes » Heading with id and classes"
+        );
     }
 
     // Setting this to `true` may cause issues with `cargo watch`,
@@ -803,7 +807,7 @@ mod search {
             let src = read_book_index(temp.path());
 
             let dest = Path::new(env!("CARGO_MANIFEST_DIR")).join("tests/searchindex_fixture.json");
-            let dest = File::create(&dest).unwrap();
+            let dest = File::create(dest).unwrap();
             serde_json::to_writer_pretty(dest, &src).unwrap();
 
             src
@@ -891,8 +895,8 @@ fn custom_fonts() {
     assert_eq!(actual_files(&p.join("book/fonts")), &builtin_fonts);
     assert!(has_fonts_css(p));
 
-    // Mixed with copy_fonts=true
+    // Mixed with copy-fonts=true
-    // This should generate a deprecation warning.
+    // Should ignore the copy-fonts setting since the user has provided their own fonts.css.
     let temp = TempFileBuilder::new().prefix("mdbook").tempdir().unwrap();
     let p = temp.path();
     MDBook::init(p).build().unwrap();
@@ -900,10 +904,10 @@ fn custom_fonts() {
     write_file(&p.join("theme/fonts"), "myfont.woff", b"").unwrap();
     MDBook::load(p).unwrap().build().unwrap();
     assert!(has_fonts_css(p));
-    let mut expected = Vec::from(builtin_fonts);
+    assert_eq!(
-    expected.push("myfont.woff");
+        actual_files(&p.join("book/fonts")),
-    expected.sort();
+        ["fonts.css", "myfont.woff"]
-    assert_eq!(actual_files(&p.join("book/fonts")), expected.as_slice());
+    );
 
     // copy-fonts=false, no theme
     // This should generate a deprecation warning.
@@ -948,3 +952,19 @@ fn custom_fonts() {
         &["fonts.css", "myfont.woff"]
     );
 }
+
+#[test]
+fn custom_header_attributes() {
+    let temp = DummyBook::new().build().unwrap();
+    let md = MDBook::load(temp.path()).unwrap();
+    md.build().unwrap();
+
+    let contents = temp.path().join("book/first/heading-attributes.html");
+
+    let summary_strings = &[
+        r##"<h1 id="attrs"><a class="header" href="#attrs">Heading Attributes</a></h1>"##,
+        r##"<h2 id="heading-with-classes" class="class1 class2"><a class="header" href="#heading-with-classes">Heading with classes</a></h2>"##,
+        r##"<h2 id="both" class="class1 class2"><a class="header" href="#both">Heading with id and classes</a></h2>"##,
+    ];
+    assert_contains_strings(&contents, summary_strings);
+}