Switch all public types to non_exhaustive

This switches all public types to use non_exhaustive to make it easier
to make additions without a semver-breaking change.

Some of the ergonomics are hampered due to the lack of exhaustiveness
checking. Hopefully some day in the future,
non_exhaustive_omitted_patterns_lint or something like it will get
stabilized.

Closes https://github.com/rust-lang/mdBook/issues/1835

Cargo.toml

@@ -9,6 +9,9 @@ members = [
 all = { level = "allow", priority = -2 }
 correctness = { level = "warn", priority = -1 }
 complexity = { level = "warn", priority = -1 }
+exhaustive_enums = "warn"
+exhaustive_structs = "warn"
+manual_non_exhaustive = "warn"
 
 [workspace.lints.rust]
 missing_docs = "warn"

crates/mdbook-core/src/book.rs

@@ -16,10 +16,10 @@ use std::path::PathBuf;
 /// [`iter()`]: #method.iter
 /// [`for_each_mut()`]: #method.for_each_mut
 #[derive(Debug, Clone, Default, PartialEq, Serialize, Deserialize)]
+#[non_exhaustive]
 pub struct Book {
     /// The sections in this book.
     pub sections: Vec<BookItem>,
-    __non_exhaustive: (),
 }
 
 impl Book {
@@ -30,10 +30,7 @@ impl Book {
 
     /// Creates a new book with the given items.
     pub fn new_with_items(items: Vec<BookItem>) -> Book {
-        Book {
+        Book { sections: items }
-            sections: items,
-            __non_exhaustive: (),
-        }
     }
 
     /// Get a depth-first iterator over the items in the book.
@@ -81,6 +78,7 @@ where
 
 /// Enum representing any type of item which can be added to a book.
 #[derive(Debug, Clone, PartialEq, Serialize, Deserialize)]
+#[non_exhaustive]
 pub enum BookItem {
     /// A nested chapter.
     Chapter(Chapter),
@@ -99,6 +97,7 @@ impl From<Chapter> for BookItem {
 /// The representation of a "chapter", usually mapping to a single file on
 /// disk however it may contain multiple sub-chapters.
 #[derive(Debug, Clone, Default, PartialEq, Serialize, Deserialize)]
+#[non_exhaustive]
 pub struct Chapter {
     /// The chapter's name.
     pub name: String,

crates/mdbook-core/src/config.rs

@@ -64,6 +64,7 @@ use toml::value::Table;
 /// The overall configuration object for MDBook, essentially an in-memory
 /// representation of `book.toml`.
 #[derive(Debug, Clone, PartialEq)]
+#[non_exhaustive]
 pub struct Config {
     /// Metadata about the book.
     pub book: BookConfig,
@@ -386,6 +387,7 @@ fn is_legacy_format(table: &Value) -> bool {
 /// loading it from disk.
 #[derive(Debug, Clone, PartialEq, Serialize, Deserialize)]
 #[serde(default, rename_all = "kebab-case")]
+#[non_exhaustive]
 pub struct BookConfig {
     /// The book's title.
     pub title: Option<String>,
@@ -429,6 +431,7 @@ impl BookConfig {
 
 /// Text direction to use for HTML output
 #[derive(Debug, Copy, Clone, PartialEq, Serialize, Deserialize)]
+#[non_exhaustive]
 pub enum TextDirection {
     /// Left to right.
     #[serde(rename = "ltr")]
@@ -454,6 +457,7 @@ impl TextDirection {
 /// Configuration for the build procedure.
 #[derive(Debug, Clone, PartialEq, Serialize, Deserialize)]
 #[serde(default, rename_all = "kebab-case")]
+#[non_exhaustive]
 pub struct BuildConfig {
     /// Where to put built artefacts relative to the book's root directory.
     pub build_dir: PathBuf,
@@ -481,13 +485,15 @@ impl Default for BuildConfig {
 /// Configuration for the Rust compiler(e.g., for playground)
 #[derive(Debug, Default, Clone, PartialEq, Serialize, Deserialize)]
 #[serde(default, rename_all = "kebab-case")]
+#[non_exhaustive]
 pub struct RustConfig {
     /// Rust edition used in playground
     pub edition: Option<RustEdition>,
 }
 
-#[derive(Debug, Copy, Clone, PartialEq, Serialize, Deserialize)]
 /// Rust edition to use for the code.
+#[derive(Debug, Copy, Clone, PartialEq, Serialize, Deserialize)]
+#[non_exhaustive]
 pub enum RustEdition {
     /// The 2024 edition of Rust
     #[serde(rename = "2024")]
@@ -506,6 +512,7 @@ pub enum RustEdition {
 /// Configuration for the HTML renderer.
 #[derive(Debug, Clone, PartialEq, Serialize, Deserialize)]
 #[serde(default, rename_all = "kebab-case")]
+#[non_exhaustive]
 pub struct HtmlConfig {
     /// The theme directory, if specified.
     pub theme: Option<PathBuf>,
@@ -625,6 +632,7 @@ impl HtmlConfig {
 /// Configuration for how to render the print icon, print.html, and print.css.
 #[derive(Debug, Clone, PartialEq, Serialize, Deserialize)]
 #[serde(default, rename_all = "kebab-case")]
+#[non_exhaustive]
 pub struct Print {
     /// Whether print support is enabled.
     pub enable: bool,
@@ -644,6 +652,7 @@ impl Default for Print {
 /// Configuration for how to fold chapters of sidebar.
 #[derive(Default, Debug, Clone, PartialEq, Serialize, Deserialize)]
 #[serde(default, rename_all = "kebab-case")]
+#[non_exhaustive]
 pub struct Fold {
     /// When off, all folds are open. Default: `false`.
     pub enable: bool,
@@ -656,6 +665,7 @@ pub struct Fold {
 /// Configuration for tweaking how the HTML renderer handles the playground.
 #[derive(Debug, Clone, PartialEq, Serialize, Deserialize)]
 #[serde(default, rename_all = "kebab-case")]
+#[non_exhaustive]
 pub struct Playground {
     /// Should playground snippets be editable? Default: `false`.
     pub editable: bool,
@@ -685,6 +695,7 @@ impl Default for Playground {
 /// Configuration for tweaking how the HTML renderer handles code blocks.
 #[derive(Debug, Default, Clone, PartialEq, Serialize, Deserialize)]
 #[serde(default, rename_all = "kebab-case")]
+#[non_exhaustive]
 pub struct Code {
     /// A prefix string to hide lines per language (one or more chars).
     pub hidelines: HashMap<String, String>,
@@ -693,6 +704,7 @@ pub struct Code {
 /// Configuration of the search functionality of the HTML renderer.
 #[derive(Debug, Clone, PartialEq, Serialize, Deserialize)]
 #[serde(default, rename_all = "kebab-case")]
+#[non_exhaustive]
 pub struct Search {
     /// Enable the search feature. Default: `true`.
     pub enable: bool,
@@ -750,6 +762,7 @@ impl Default for Search {
 /// Search options for chapters (or paths).
 #[derive(Debug, Clone, PartialEq, Serialize, Deserialize, Default)]
 #[serde(default, rename_all = "kebab-case")]
+#[non_exhaustive]
 pub struct SearchChapterSettings {
     /// Whether or not indexing is enabled, default `true`.
     pub enable: Option<bool>,

crates/mdbook-driver/src/builtin_preprocessors/index.rs

@@ -8,6 +8,7 @@ use std::{path::Path, sync::LazyLock};
 /// A preprocessor for converting file name `README.md` to `index.md` since
 /// `README.md` is the de facto index file in markdown-based documentation.
 #[derive(Default)]
+#[non_exhaustive]
 pub struct IndexPreprocessor;
 
 impl IndexPreprocessor {

crates/mdbook-driver/src/builtin_preprocessors/links.rs

@@ -26,6 +26,7 @@ const MAX_LINK_NESTED_DEPTH: usize = 10;
 /// - `{{# playground}}` - Insert runnable Rust files
 /// - `{{# title}}` - Override \<title\> of a webpage.
 #[derive(Default)]
+#[non_exhaustive]
 pub struct LinkPreprocessor;
 
 impl LinkPreprocessor {

crates/mdbook-driver/src/builtin_renderers/markdown_renderer.rs

@@ -5,9 +5,10 @@ use mdbook_core::utils;
 use mdbook_renderer::{RenderContext, Renderer};
 use std::fs;
 
-#[derive(Default)]
 /// A renderer to output the Markdown after the preprocessors have run. Mostly useful
 /// when debugging preprocessors.
+#[derive(Default)]
+#[non_exhaustive]
 pub struct MarkdownRenderer;
 
 impl MarkdownRenderer {

crates/mdbook-driver/src/load.rs

@@ -95,6 +95,7 @@ fn load_summary_item<P: AsRef<Path> + Clone>(
         SummaryItem::Separator => Ok(BookItem::Separator),
         SummaryItem::Link(link) => load_chapter(link, src_dir, parent_names).map(BookItem::Chapter),
         SummaryItem::PartTitle(title) => Ok(BookItem::PartTitle(title.clone())),
+        _ => panic!("SummaryItem {item:?} not covered"),
     }
 }
 
@@ -252,28 +253,21 @@ And here is some \
     fn load_recursive_link_with_separators() {
         let (root, temp) = nested_links();
 
-        let nested = Chapter {
+        let mut nested = Chapter::new(
-            name: String::from("Nested Chapter 1"),
+            "Nested Chapter 1",
-            content: String::from("Hello World!"),
+            String::from("Hello World!"),
-            number: Some(SectionNumber::new([1, 2])),
+            "second.md",
-            path: Some(PathBuf::from("second.md")),
+            vec![String::from("Chapter 1")],
-            source_path: Some(PathBuf::from("second.md")),
+        );
-            parent_names: vec![String::from("Chapter 1")],
+        nested.number = Some(SectionNumber::new([1, 2]));
-            sub_items: Vec::new(),
+        let mut chapter =
-        };
+            Chapter::new("Chapter 1", String::from(DUMMY_SRC), "chapter_1.md", vec![]);
-        let should_be = BookItem::Chapter(Chapter {
+        chapter.sub_items = vec![
-            name: String::from("Chapter 1"),
-            content: String::from(DUMMY_SRC),
-            number: None,
-            path: Some(PathBuf::from("chapter_1.md")),
-            source_path: Some(PathBuf::from("chapter_1.md")),
-            parent_names: Vec::new(),
-            sub_items: vec![
             BookItem::Chapter(nested.clone()),
             BookItem::Separator,
             BookItem::Chapter(nested),
-            ],
+        ];
-        });
+        let should_be = BookItem::Chapter(chapter);
 
         let got = load_summary_item(&SummaryItem::Link(root), temp.path(), Vec::new()).unwrap();
         assert_eq!(got, should_be);
@@ -282,17 +276,15 @@ And here is some \
     #[test]
     fn load_a_book_with_a_single_chapter() {
         let (link, temp) = dummy_link();
-        let summary = Summary {
+        let mut summary = Summary::default();
-            numbered_chapters: vec![SummaryItem::Link(link)],
+        summary.numbered_chapters = vec![SummaryItem::Link(link)];
-            ..Default::default()
+        let chapter = Chapter::new(
-        };
+            "Chapter 1",
-        let sections = vec![BookItem::Chapter(Chapter {
+            String::from(DUMMY_SRC),
-            name: String::from("Chapter 1"),
+            PathBuf::from("chapter_1.md"),
-            content: String::from(DUMMY_SRC),
+            vec![],
-            path: Some(PathBuf::from("chapter_1.md")),
+        );
-            source_path: Some(PathBuf::from("chapter_1.md")),
+        let sections = vec![BookItem::Chapter(chapter)];
-            ..Default::default()
-        })];
         let should_be = Book::new_with_items(sections);
 
         let got = load_book_from_disk(&summary, temp.path()).unwrap();
@@ -303,16 +295,9 @@ And here is some \
     #[test]
     fn cant_load_chapters_with_an_empty_path() {
         let (_, temp) = dummy_link();
-        let summary = Summary {
+        let mut summary = Summary::default();
-            numbered_chapters: vec![SummaryItem::Link(Link {
+        let link = Link::new("Empty", "");
-                name: String::from("Empty"),
+        summary.numbered_chapters = vec![SummaryItem::Link(link)];
-                location: Some(PathBuf::from("")),
-                ..Default::default()
-            })],
-
-            ..Default::default()
-        };
-
         let got = load_book_from_disk(&summary, temp.path());
         assert!(got.is_err());
     }
@@ -323,14 +308,9 @@ And here is some \
         let dir = temp.path().join("nested");
         fs::create_dir(&dir).unwrap();
 
-        let summary = Summary {
+        let mut summary = Summary::default();
-            numbered_chapters: vec![SummaryItem::Link(Link {
+        let link = Link::new("nested", dir);
-                name: String::from("nested"),
+        summary.numbered_chapters = vec![SummaryItem::Link(link)];
-                location: Some(dir),
-                ..Default::default()
-            })],
-            ..Default::default()
-        };
 
         let got = load_book_from_disk(&summary, temp.path());
         assert!(got.is_err());

crates/mdbook-driver/src/mdbook.rs

@@ -136,6 +136,7 @@ impl MDBook {
     ///         BookItem::Chapter(ref chapter) => {},
     ///         BookItem::Separator => {},
     ///         BookItem::PartTitle(ref title) => {}
+    ///         _ => {}
     ///     }
     /// }
     ///
@@ -329,6 +330,7 @@ impl MDBook {
                         RustEdition::E2024 => {
                             cmd.args(["--edition", "2024"]);
                         }
+                        _ => panic!("RustEdition {edition:?} not covered"),
                     }
                 }
 

crates/mdbook-driver/src/mdbook/tests.rs

@@ -230,7 +230,7 @@ fn config_respects_preprocessor_selection() {
 
     let cfg = Config::from_str(cfg_str).unwrap();
 
-    let html_renderer = HtmlHandlebars;
+    let html_renderer = HtmlHandlebars::default();
     let pre = LinkPreprocessor::new();
 
     let should_run = preprocessor_should_run(&pre, &html_renderer, &cfg).unwrap();

crates/mdbook-html/src/html_handlebars/hbs_renderer.rs

@@ -21,6 +21,7 @@ use std::sync::LazyLock;
 
 /// The HTML renderer for mdBook.
 #[derive(Default)]
+#[non_exhaustive]
 pub struct HtmlHandlebars;
 
 impl HtmlHandlebars {
@@ -656,6 +657,7 @@ fn make_data(
             BookItem::Separator => {
                 chapter.insert("spacer".to_owned(), json!("_spacer_"));
             }
+            _ => panic!("BookItem {item:?} not covered"),
         }
 
         chapters.push(chapter);
@@ -778,6 +780,7 @@ fn add_playground_pre(
                         Some(RustEdition::E2018) => " edition2018",
                         Some(RustEdition::E2021) => " edition2021",
                         Some(RustEdition::E2024) => " edition2024",
+                        Some(_) => panic!("edition {edition:?} not covered"),
                         None => "",
                     }
                 };
@@ -1085,14 +1088,9 @@ mod tests {
             ),
         ];
         for (src, should_be) in &inputs {
-            let got = add_playground_pre(
+            let mut p = Playground::default();
-                src,
+            p.editable = true;
-                &Playground {
+            let got = add_playground_pre(src, &p, None);
-                    editable: true,
-                    ..Playground::default()
-                },
-                None,
-            );
             assert_eq!(&*got, *should_be);
         }
     }
@@ -1117,14 +1115,9 @@ mod tests {
             ),
         ];
         for (src, should_be) in &inputs {
-            let got = add_playground_pre(
+            let mut p = Playground::default();
-                src,
+            p.editable = true;
-                &Playground {
+            let got = add_playground_pre(src, &p, Some(RustEdition::E2015));
-                    editable: true,
-                    ..Playground::default()
-                },
-                Some(RustEdition::E2015),
-            );
             assert_eq!(&*got, *should_be);
         }
     }
@@ -1149,14 +1142,9 @@ mod tests {
             ),
         ];
         for (src, should_be) in &inputs {
-            let got = add_playground_pre(
+            let mut p = Playground::default();
-                src,
+            p.editable = true;
-                &Playground {
+            let got = add_playground_pre(src, &p, Some(RustEdition::E2018));
-                    editable: true,
-                    ..Playground::default()
-                },
-                Some(RustEdition::E2018),
-            );
             assert_eq!(&*got, *should_be);
         }
     }
@@ -1181,14 +1169,9 @@ mod tests {
             ),
         ];
         for (src, should_be) in &inputs {
-            let got = add_playground_pre(
+            let mut p = Playground::default();
-                src,
+            p.editable = true;
-                &Playground {
+            let got = add_playground_pre(src, &p, Some(RustEdition::E2021));
-                    editable: true,
-                    ..Playground::default()
-                },
-                Some(RustEdition::E2021),
-            );
             assert_eq!(&*got, *should_be);
         }
     }
@@ -1248,17 +1231,10 @@ mod tests {
                 "<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>",
             ),
         ];
+        let mut code = Code::default();
+        code.hidelines.insert("python".to_string(), "~".to_string());
         for (src, should_be) in &inputs {
-            let got = hide_lines(
+            let got = hide_lines(src, &code);
-                src,
-                &Code {
-                    hidelines: {
-                        let mut map = HashMap::new();
-                        map.insert("python".to_string(), "~".to_string());
-                        map
-                    },
-                },
-            );
             assert_eq!(&*got, *should_be);
         }
     }

crates/mdbook-html/src/html_handlebars/search.rs

@@ -409,9 +409,11 @@ fn chapter_settings_priority() {
         ("cli/inner/index.md", Some(true)),
         ("cli/inner/foo.md", Some(false)),
     ] {
+        let mut settings = SearchChapterSettings::default();
+        settings.enable = enable;
         assert_eq!(
             get_chapter_settings(&chapter_configs, Path::new(path)),
-            SearchChapterSettings { enable }
+            settings
         );
     }
 }

crates/mdbook-html/src/theme/mod.rs

@@ -49,6 +49,7 @@ pub static FONT_AWESOME_OTF: &[u8] = include_bytes!("../../front-end/fonts/FontA
 /// You should only ever use the static variables directly if you want to
 /// override the user's theme with the defaults.
 #[derive(Debug, PartialEq)]
+#[non_exhaustive]
 pub struct Theme {
     pub index: Vec<u8>,
     pub head: Vec<u8>,

crates/mdbook-preprocessor/src/lib.rs

@@ -47,6 +47,7 @@ pub trait Preprocessor {
 /// Extra information for a `Preprocessor` to give them more context when
 /// processing a book.
 #[derive(Debug, Clone, PartialEq, Serialize, Deserialize)]
+#[non_exhaustive]
 pub struct PreprocessorContext {
     /// The location of the book directory on disk.
     pub root: PathBuf,
@@ -62,8 +63,6 @@ pub struct PreprocessorContext {
     /// This should not be used outside of mdbook's internals.
     #[serde(skip)]
     pub chapter_titles: RefCell<HashMap<PathBuf, String>>,
-    #[serde(skip)]
-    __non_exhaustive: (),
 }
 
 impl PreprocessorContext {
@@ -75,7 +74,6 @@ impl PreprocessorContext {
             renderer,
             mdbook_version: crate::MDBOOK_VERSION.to_string(),
             chapter_titles: RefCell::new(HashMap::new()),
-            __non_exhaustive: (),
         }
     }
 }

crates/mdbook-renderer/src/lib.rs

@@ -36,6 +36,7 @@ pub trait Renderer {
 
 /// The context provided to all renderers.
 #[derive(Debug, Clone, PartialEq, Serialize, Deserialize)]
+#[non_exhaustive]
 pub struct RenderContext {
     /// Which version of `mdbook` did this come from (as written in `mdbook`'s
     /// `Cargo.toml`). Useful if you know the renderer is only compatible with
@@ -57,8 +58,6 @@ pub struct RenderContext {
     /// This should not be used outside of mdbook's internals.
     #[serde(skip)]
     pub chapter_titles: HashMap<PathBuf, String>,
-    #[serde(skip)]
-    __non_exhaustive: (),
 }
 
 impl RenderContext {
@@ -75,7 +74,6 @@ impl RenderContext {
             root: root.into(),
             destination: destination.into(),
             chapter_titles: HashMap::new(),
-            __non_exhaustive: (),
         }
     }
 

crates/mdbook-summary/src/lib.rs

@@ -63,6 +63,7 @@ pub fn parse_summary(summary: &str) -> Result<Summary> {
 
 /// The parsed `SUMMARY.md`, specifying how the book should be laid out.
 #[derive(Debug, Clone, Default, PartialEq, Serialize, Deserialize)]
+#[non_exhaustive]
 pub struct Summary {
     /// An optional title for the `SUMMARY.md`, currently just ignored.
     pub title: Option<String>,
@@ -79,6 +80,7 @@ pub struct Summary {
 ///
 /// This is roughly the equivalent of `[Some section](./path/to/file.md)`.
 #[derive(Debug, Clone, PartialEq, Serialize, Deserialize)]
+#[non_exhaustive]
 pub struct Link {
     /// The name of the chapter.
     pub name: String,
@@ -114,8 +116,9 @@ impl Default for Link {
     }
 }
 
-/// An item in `SUMMARY.md` which could be either a separator or a `Link`.
+/// An item in `SUMMARY.md`.
 #[derive(Debug, Clone, PartialEq, Serialize, Deserialize)]
+#[non_exhaustive]
 pub enum SummaryItem {
     /// A link to a chapter.
     Link(Link),

examples/nop-preprocessor.rs

@@ -146,8 +146,7 @@ mod nop_lib {
                                 "parent_names": []
                             }
                         }
-                    ],
+                    ]
-                    "__non_exhaustive": null
                 }
             ]"##;
             let input_json = input_json.as_bytes();

tests/testsuite/renderer.rs

@@ -167,7 +167,6 @@ fn backends_receive_render_context_via_stdin() {
         str![[r##"
 {
   "book": {
-    "__non_exhaustive": null,
     "sections": [
       {
         "Chapter": {

tests/testsuite/search.rs

@@ -3,7 +3,7 @@
 use crate::prelude::*;
 use mdbook_core::book::{BookItem, Chapter};
 use snapbox::file;
-use std::path::{Path, PathBuf};
+use std::path::Path;
 
 fn read_book_index(root: &Path) -> serde_json::Value {
     let index = root.join("book/searchindex.js");
@@ -116,15 +116,7 @@ fn can_disable_individual_chapters() {
 fn with_no_source_path() {
     let test = BookTest::from_dir("search/reasonable_search_index");
     let mut book = test.load_book();
-    let chapter = Chapter {
+    let chapter = Chapter::new("Sample chapter", String::new(), "sample.html", vec![]);
-        name: "Sample chapter".to_string(),
-        content: "".to_string(),
-        number: None,
-        sub_items: Vec::new(),
-        path: Some(PathBuf::from("sample.html")),
-        source_path: None,
-        parent_names: Vec::new(),
-    };
     book.book.sections.push(BookItem::Chapter(chapter));
     book.build().unwrap();
 }