7 files changed, 225 insertions, 270 deletions

diff --git a/src/tools/error_index_generator/Cargo.toml b/src/tools/error_index_generator/Cargo.toml
index c84b79e11..f4dac6e94 100644
--- a/src/tools/error_index_generator/Cargo.toml
+++ b/src/tools/error_index_generator/Cargo.toml
@@ -4,10 +4,7 @@ version = "0.0.0"
 edition = "2021"
 
 [dependencies]
-rustdoc = { path = "../../librustdoc" }
-
-[build-dependencies]
-walkdir = "2"
+mdbook = { version = "0.4", default-features = false, features = ["search"] }
 
 [[bin]]
 name = "error_index_generator"
diff --git a/src/tools/error_index_generator/book_config.toml b/src/tools/error_index_generator/book_config.toml
new file mode 100644
index 000000000..885100ae3
--- /dev/null
+++ b/src/tools/error_index_generator/book_config.toml
@@ -0,0 +1,19 @@
+[book]
+title = "Error codes index"
+description = "Book listing all Rust error codes"
+src = ""
+
+[output.html]
+git-repository-url = "https://github.com/rust-lang/rust/"
+additional-css = ["error-index.css"]
+additional-js = ["error-index.js"]
+
+[output.html.search]
+enable = true
+limit-results = 20
+use-boolean-and = true
+boost-title = 2
+boost-hierarchy = 2
+boost-paragraph = 1
+expand = true
+heading-split-level = 0
diff --git a/src/tools/error_index_generator/build.rs b/src/tools/error_index_generator/build.rs
deleted file mode 100644
index 70b00b36c..000000000
--- a/src/tools/error_index_generator/build.rs
+++ /dev/null
@@ -1,31 +0,0 @@
-use std::path::PathBuf;
-use std::{env, fs};
-use walkdir::WalkDir;
-
-fn main() {
-    // The src directory (we are in src/tools/error_index_generator)
-    // Note that we could skip one of the .. but this ensures we at least loosely find the right
-    // directory.
-    let out_dir = PathBuf::from(env::var("OUT_DIR").unwrap());
-
-    let error_codes_path = "../../../compiler/rustc_error_codes/src/error_codes.rs";
-
-    println!("cargo:rerun-if-changed={}", error_codes_path);
-    let file = fs::read_to_string(error_codes_path)
-        .unwrap()
-        .replace(": include_str!(\"./error_codes/", ": include_str!(\"./");
-    let contents = format!("(|| {{\n{}\n}})()", file);
-    fs::write(&out_dir.join("all_error_codes.rs"), &contents).unwrap();
-
-    // We copy the md files as well to the target directory.
-    for entry in WalkDir::new("../../../compiler/rustc_error_codes/src/error_codes") {
-        let entry = entry.unwrap();
-        match entry.path().extension() {
-            Some(s) if s == "md" => {}
-            _ => continue,
-        }
-        println!("cargo:rerun-if-changed={}", entry.path().to_str().unwrap());
-        let md_content = fs::read_to_string(entry.path()).unwrap();
-        fs::write(&out_dir.join(entry.file_name()), &md_content).unwrap();
-    }
-}
diff --git a/src/tools/error_index_generator/error-index.css b/src/tools/error_index_generator/error-index.css
new file mode 100644
index 000000000..8975af82d
--- /dev/null
+++ b/src/tools/error_index_generator/error-index.css
@@ -0,0 +1,38 @@
+code.compile_fail {
+	border-left: 2px solid red;
+}
+
+pre .tooltip {
+	position: absolute;
+	left: -25px;
+	top: 0;
+	z-index: 1;
+	color: red;
+	cursor: pointer;
+}
+pre .tooltip::after {
+	display: none;
+	content: "This example deliberately fails to compile";
+	background-color: #000;
+	color: #fff;
+	border-color: #000;
+	text-align: center;
+	padding: 5px 3px 3px 3px;
+	border-radius: 6px;
+	margin-left: 5px;
+}
+pre .tooltip::before {
+	display: none;
+	border-color: transparent black transparent transparent;
+	content: " ";
+	position: absolute;
+	top: 50%;
+	left: 16px;
+	margin-top: -5px;
+	border-width: 5px;
+	border-style: solid;
+}
+
+pre .tooltip:hover::before, pre .tooltip:hover::after {
+	display: inline;
+}
diff --git a/src/tools/error_index_generator/error-index.js b/src/tools/error_index_generator/error-index.js
new file mode 100644
index 000000000..39b371be0
--- /dev/null
+++ b/src/tools/error_index_generator/error-index.js
@@ -0,0 +1,9 @@
+for (const elem of document.querySelectorAll("pre.playground")) {
+    if (elem.querySelector(".compile_fail") === null) {
+        continue;
+    }
+    const child = document.createElement("div");
+    child.className = "tooltip";
+    child.textContent = "ⓘ";
+    elem.appendChild(child);
+}
diff --git a/src/tools/error_index_generator/main.rs b/src/tools/error_index_generator/main.rs
index 1ce02e48c..1bde8e007 100644
--- a/src/tools/error_index_generator/main.rs
+++ b/src/tools/error_index_generator/main.rs
@@ -1,267 +1,195 @@
 #![feature(rustc_private)]
 
 extern crate rustc_driver;
-extern crate rustc_span;
 
-use std::cell::RefCell;
-use std::collections::BTreeMap;
+// We use the function we generate from `register_diagnostics!`.
+use crate::error_codes::error_codes;
+
 use std::env;
 use std::error::Error;
-use std::fs::File;
+use std::fs::{self, File};
 use std::io::Write;
 use std::path::Path;
 use std::path::PathBuf;
 
-use rustc_span::edition::DEFAULT_EDITION;
+use std::str::FromStr;
 
-use rustdoc::html::markdown::{ErrorCodes, HeadingOffset, IdMap, Markdown, Playground};
+use mdbook::book::{parse_summary, BookItem, Chapter};
+use mdbook::{Config, MDBook};
 
-pub struct ErrorMetadata {
-    pub description: Option<String>,
+macro_rules! register_diagnostics {
+    ($($error_code:ident: $message:expr,)+ ; $($undocumented:ident,)* ) => {
+        pub fn error_codes() -> Vec<(&'static str, Option<&'static str>)> {
+            let mut errors: Vec<(&str, Option<&str>)> = vec![
+                $((stringify!($error_code), Some($message)),)+
+                $((stringify!($undocumented), None),)+
+            ];
+            errors.sort();
+            errors
+        }
+    }
 }
 
-/// Mapping from error codes to metadata that can be (de)serialized.
-pub type ErrorMetadataMap = BTreeMap<String, ErrorMetadata>;
+#[path = "../../../compiler/rustc_error_codes/src/error_codes.rs"]
+mod error_codes;
 
 enum OutputFormat {
-    HTML(HTMLFormatter),
-    Markdown(MarkdownFormatter),
+    HTML,
+    Markdown,
     Unknown(String),
 }
 
 impl OutputFormat {
-    fn from(format: &str, resource_suffix: &str) -> OutputFormat {
+    fn from(format: &str) -> OutputFormat {
         match &*format.to_lowercase() {
-            "html" => OutputFormat::HTML(HTMLFormatter(
-                RefCell::new(IdMap::new()),
-                resource_suffix.to_owned(),
-            )),
-            "markdown" => OutputFormat::Markdown(MarkdownFormatter),
+            "html" => OutputFormat::HTML,
+            "markdown" => OutputFormat::Markdown,
             s => OutputFormat::Unknown(s.to_owned()),
         }
     }
 }
 
-trait Formatter {
-    fn header(&self, output: &mut dyn Write) -> Result<(), Box<dyn Error>>;
-    fn title(&self, output: &mut dyn Write) -> Result<(), Box<dyn Error>>;
-    fn error_code_block(
-        &self,
-        output: &mut dyn Write,
-        info: &ErrorMetadata,
-        err_code: &str,
-    ) -> Result<(), Box<dyn Error>>;
-    fn footer(&self, output: &mut dyn Write) -> Result<(), Box<dyn Error>>;
-}
-
-struct HTMLFormatter(RefCell<IdMap>, String);
-struct MarkdownFormatter;
+/// Output an HTML page for the errors in `err_map` to `output_path`.
+fn render_markdown(output_path: &Path) -> Result<(), Box<dyn Error>> {
+    let mut output_file = File::create(output_path)?;
 
-impl Formatter for HTMLFormatter {
-    fn header(&self, output: &mut dyn Write) -> Result<(), Box<dyn Error>> {
-        write!(
-            output,
-            r##"<!DOCTYPE html>
-<html>
-<head>
-<title>Rust Compiler Error Index</title>
-<meta charset="utf-8">
-<!-- Include rust.css after light.css so its rules take priority. -->
-<link rel="stylesheet" type="text/css" href="rustdoc{suffix}.css"/>
-<link rel="stylesheet" type="text/css" href="light{suffix}.css"/>
-<link rel="stylesheet" type="text/css" href="rust.css"/>
-<style>
-.error-undescribed {{
-    display: none;
-}}
-</style>
-</head>
-<body>
-"##,
-            suffix = self.1
-        )?;
-        Ok(())
-    }
+    write!(output_file, "# Rust Compiler Error Index\n")?;
 
-    fn title(&self, output: &mut dyn Write) -> Result<(), Box<dyn Error>> {
-        write!(output, "<h1>Rust Compiler Error Index</h1>\n")?;
-        Ok(())
+    for (err_code, description) in error_codes().iter() {
+        match description {
+            Some(ref desc) => write!(output_file, "## {}\n{}\n", err_code, desc)?,
+            None => {}
+        }
     }
 
-    fn error_code_block(
-        &self,
-        output: &mut dyn Write,
-        info: &ErrorMetadata,
-        err_code: &str,
-    ) -> Result<(), Box<dyn Error>> {
-        // Enclose each error in a div so they can be shown/hidden en masse.
-        let desc_desc = match info.description {
-            Some(_) => "error-described",
-            None => "error-undescribed",
-        };
-        write!(output, "<div class=\"{}\">", desc_desc)?;
-
-        // Error title (with self-link).
-        write!(
-            output,
-            "<h2 id=\"{0}\" class=\"section-header\"><a href=\"#{0}\">{0}</a></h2>\n",
-            err_code
-        )?;
+    Ok(())
+}
 
-        // Description rendered as markdown.
-        match info.description {
-            Some(ref desc) => {
-                let mut id_map = self.0.borrow_mut();
-                let playground = Playground {
-                    crate_name: None,
-                    url: String::from("https://play.rust-lang.org/"),
-                };
-                write!(
-                    output,
-                    "{}",
-                    Markdown {
-                        content: desc,
-                        links: &[],
-                        ids: &mut id_map,
-                        error_codes: ErrorCodes::Yes,
-                        edition: DEFAULT_EDITION,
-                        playground: &Some(playground),
-                        heading_offset: HeadingOffset::H1,
+// By default, mdbook doesn't consider code blocks as Rust ones contrary to rustdoc so we have
+// to manually add `rust` attribute whenever needed.
+fn add_rust_attribute_on_codeblock(explanation: &str) -> String {
+    // Very hacky way to add the rust attribute on all code blocks.
+    let mut skip = true;
+    explanation.split("\n```").fold(String::new(), |mut acc, part| {
+        if !acc.is_empty() {
+            acc.push_str("\n```");
+        }
+        if !skip {
+            if let Some(attrs) = part.split('\n').next() {
+                if !attrs.contains("rust")
+                    && (attrs.is_empty()
+                        || attrs.contains("compile_fail")
+                        || attrs.contains("ignore")
+                        || attrs.contains("edition"))
+                {
+                    if !attrs.is_empty() {
+                        acc.push_str("rust,");
+                    } else {
+                        acc.push_str("rust");
                     }
-                    .into_string()
-                )?
+                }
             }
-            None => write!(output, "<p>No description.</p>\n")?,
         }
-
-        write!(output, "</div>\n")?;
-        Ok(())
-    }
-
-    fn footer(&self, output: &mut dyn Write) -> Result<(), Box<dyn Error>> {
-        write!(
-            output,
-            r##"<script>
-function onEach(arr, func) {{
-    if (arr && arr.length > 0 && func) {{
-        var length = arr.length;
-        var i;
-        for (i = 0; i < length; ++i) {{
-            if (func(arr[i])) {{
-                return true;
-            }}
-        }}
-    }}
-    return false;
-}}
-
-function onEachLazy(lazyArray, func) {{
-    return onEach(
-        Array.prototype.slice.call(lazyArray),
-        func);
-}}
-
-function hasClass(elem, className) {{
-    return elem && elem.classList && elem.classList.contains(className);
-}}
-
-onEachLazy(document.getElementsByClassName('rust-example-rendered'), function(e) {{
-    if (hasClass(e, 'compile_fail')) {{
-        e.addEventListener("mouseover", function(event) {{
-            e.parentElement.previousElementSibling.childNodes[0].style.color = '#f00';
-        }});
-        e.addEventListener("mouseout", function(event) {{
-            e.parentElement.previousElementSibling.childNodes[0].style.color = '';
-        }});
-    }} else if (hasClass(e, 'ignore')) {{
-        e.addEventListener("mouseover", function(event) {{
-            e.parentElement.previousElementSibling.childNodes[0].style.color = '#ff9200';
-        }});
-        e.addEventListener("mouseout", function(event) {{
-            e.parentElement.previousElementSibling.childNodes[0].style.color = '';
-        }});
-    }}
-}});
-</script>
-</body>
-</html>"##
-        )?;
-        Ok(())
-    }
+        skip = !skip;
+        acc.push_str(part);
+        acc
+    })
 }
 
-impl Formatter for MarkdownFormatter {
-    #[allow(unused_variables)]
-    fn header(&self, output: &mut dyn Write) -> Result<(), Box<dyn Error>> {
-        Ok(())
-    }
-
-    fn title(&self, output: &mut dyn Write) -> Result<(), Box<dyn Error>> {
-        write!(output, "# Rust Compiler Error Index\n")?;
-        Ok(())
-    }
-
-    fn error_code_block(
-        &self,
-        output: &mut dyn Write,
-        info: &ErrorMetadata,
-        err_code: &str,
-    ) -> Result<(), Box<dyn Error>> {
-        Ok(match info.description {
-            Some(ref desc) => write!(output, "## {}\n{}\n", err_code, desc)?,
-            None => (),
-        })
-    }
-
-    #[allow(unused_variables)]
-    fn footer(&self, output: &mut dyn Write) -> Result<(), Box<dyn Error>> {
-        Ok(())
+fn render_html(output_path: &Path) -> Result<(), Box<dyn Error>> {
+    let mut introduction = format!(
+        "<script src='redirect.js'></script>
+# Rust error codes index
+
+This page lists all the error codes emitted by the Rust compiler.
+
+"
+    );
+
+    let err_codes = error_codes();
+    let mut chapters = Vec::with_capacity(err_codes.len());
+
+    for (err_code, explanation) in err_codes.iter() {
+        if let Some(explanation) = explanation {
+            introduction.push_str(&format!(" * [{0}](./{0}.html)\n", err_code));
+
+            let content = add_rust_attribute_on_codeblock(explanation);
+            chapters.push(BookItem::Chapter(Chapter {
+                name: err_code.to_string(),
+                content: format!("# Error code {}\n\n{}\n", err_code, content),
+                number: None,
+                sub_items: Vec::new(),
+                // We generate it into the `error_codes` folder.
+                path: Some(PathBuf::from(&format!("{}.html", err_code))),
+                source_path: None,
+                parent_names: Vec::new(),
+            }));
+        } else {
+            introduction.push_str(&format!(" * {}\n", err_code));
+        }
     }
-}
-
-/// Output an HTML page for the errors in `err_map` to `output_path`.
-fn render_error_page<T: Formatter>(
-    err_map: &ErrorMetadataMap,
-    output_path: &Path,
-    formatter: T,
-) -> Result<(), Box<dyn Error>> {
-    let mut output_file = File::create(output_path)?;
-
-    formatter.header(&mut output_file)?;
-    formatter.title(&mut output_file)?;
 
-    for (err_code, info) in err_map {
-        formatter.error_code_block(&mut output_file, info, err_code)?;
-    }
+    let mut config = Config::from_str(include_str!("book_config.toml"))?;
+    config.build.build_dir = output_path.join("error_codes").to_path_buf();
+    let mut book = MDBook::load_with_config_and_summary(
+        env!("CARGO_MANIFEST_DIR"),
+        config,
+        parse_summary("")?,
+    )?;
+    let chapter = Chapter {
+        name: "Rust error codes index".to_owned(),
+        content: introduction,
+        number: None,
+        sub_items: chapters,
+        // Very important: this file is named as `error-index.html` and not `index.html`!
+        path: Some(PathBuf::from("error-index.html")),
+        source_path: None,
+        parent_names: Vec::new(),
+    };
+    book.book.sections.push(BookItem::Chapter(chapter));
+    book.build()?;
+
+    // We can't put this content into another file, otherwise `mbdbook` will also put it into the
+    // output directory, making a duplicate.
+    fs::write(
+        output_path.join("error-index.html"),
+        r#"<!DOCTYPE html>
+<html>
+    <head>
+        <title>Rust error codes index - Error codes index</title>
+        <meta content="text/html; charset=utf-8" http-equiv="Content-Type">
+        <meta name="description" content="Book listing all Rust error codes">
+        <script src="error_codes/redirect.js"></script>
+    </head>
+    <body>
+        <div>If you are not automatically redirected to the error code index, please <a id="index-link" href="./error_codes/error-index.html">here</a>.
+        <script>document.getElementById("index-link").click()</script>
+    </body>
+</html>"#,
+    )?;
+
+    // No need for a 404 file, it's already handled by the server.
+    fs::remove_file(output_path.join("error_codes/404.html"))?;
 
-    formatter.footer(&mut output_file)
+    Ok(())
 }
 
 fn main_with_result(format: OutputFormat, dst: &Path) -> Result<(), Box<dyn Error>> {
-    let long_codes = register_all();
-    let mut err_map = BTreeMap::new();
-    for (code, desc) in long_codes {
-        err_map.insert(code.to_string(), ErrorMetadata { description: desc.map(String::from) });
-    }
     match format {
         OutputFormat::Unknown(s) => panic!("Unknown output format: {}", s),
-        OutputFormat::HTML(h) => render_error_page(&err_map, dst, h)?,
-        OutputFormat::Markdown(m) => render_error_page(&err_map, dst, m)?,
+        OutputFormat::HTML => render_html(dst),
+        OutputFormat::Markdown => render_markdown(dst),
     }
-    Ok(())
 }
 
 fn parse_args() -> (OutputFormat, PathBuf) {
     let mut args = env::args().skip(1);
     let format = args.next();
     let dst = args.next();
-    let resource_suffix = args.next().unwrap_or_else(String::new);
-    let format = format
-        .map(|a| OutputFormat::from(&a, &resource_suffix))
-        .unwrap_or(OutputFormat::from("html", &resource_suffix));
+    let format = format.map(|a| OutputFormat::from(&a)).unwrap_or(OutputFormat::from("html"));
     let dst = dst.map(PathBuf::from).unwrap_or_else(|| match format {
-        OutputFormat::HTML(..) => PathBuf::from("doc/error-index.html"),
-        OutputFormat::Markdown(..) => PathBuf::from("doc/error-index.md"),
+        OutputFormat::HTML => PathBuf::from("doc"),
+        OutputFormat::Markdown => PathBuf::from("doc/error-index.md"),
         OutputFormat::Unknown(..) => PathBuf::from("<nul>"),
     });
     (format, dst)
@@ -270,29 +198,8 @@ fn parse_args() -> (OutputFormat, PathBuf) {
 fn main() {
     rustc_driver::init_env_logger("RUST_LOG");
     let (format, dst) = parse_args();
-    let result =
-        rustc_span::create_default_session_globals_then(move || main_with_result(format, &dst));
+    let result = main_with_result(format, &dst);
     if let Err(e) = result {
-        panic!("{}", e.to_string());
-    }
-}
-
-fn register_all() -> Vec<(&'static str, Option<&'static str>)> {
-    let mut long_codes: Vec<(&'static str, Option<&'static str>)> = Vec::new();
-    macro_rules! register_diagnostics {
-        ($($ecode:ident: $message:expr,)* ; $($code:ident,)*) => (
-            $(
-                {long_codes.extend([
-                    (stringify!($ecode), Some($message)),
-                ].iter());}
-            )*
-            $(
-                {long_codes.extend([
-                    stringify!($code),
-                ].iter().cloned().map(|s| (s, None)).collect::<Vec<_>>());}
-            )*
-        )
+        panic!("{:?}", e);
     }
-    include!(concat!(env!("OUT_DIR"), "/all_error_codes.rs"));
-    long_codes
 }
diff --git a/src/tools/error_index_generator/redirect.js b/src/tools/error_index_generator/redirect.js
new file mode 100644
index 000000000..8c907f579
--- /dev/null
+++ b/src/tools/error_index_generator/redirect.js
@@ -0,0 +1,16 @@
+(function() {
+    if (window.location.hash) {
+        let code = window.location.hash.replace(/^#/, '');
+        // We have to make sure this pattern matches to avoid inadvertently creating an
+        // open redirect.
+        if (!/^E[0-9]+$/.test(code)) {
+            return;
+        }
+        if (window.location.pathname.indexOf("/error_codes/") !== -1) {
+            // We're not at the top level, so we don't prepend with "./error_codes/".
+            window.location = './' + code + '.html';
+        } else {
+            window.location = './error_codes/' + code + '.html';
+        }
+    }
+})()