Add submodule for document translation

.gitmodules

@@ -55,3 +55,6 @@
 	path = src/gcc
 	url = https://github.com/rust-lang/gcc.git
 	shallow = true
+[submodule "src/doc/translations"]
+	path = src/doc/translations
+	url = https://github.com/dalance/translations

src/bootstrap/src/core/build_steps/doc.rs

@@ -177,6 +177,8 @@ impl<P: Step> Step for RustbookSrc<P> {
                 .arg(&out)
                 .arg("--rust-root")
                 .arg(&builder.src)
+                .arg("-n")
+                .arg(&name)
                 .run(builder);
 
             for lang in &self.languages {
@@ -191,6 +193,10 @@ impl<P: Step> Step for RustbookSrc<P> {
                     .arg(&src)
                     .arg("-d")
                     .arg(&out)
+                    .arg("--rust-root")
+                    .arg(&builder.src)
+                    .arg("-n")
+                    .arg(&name)
                     .arg("-l")
                     .arg(lang)
                     .run(builder);

src/tools/rustbook/Cargo.lock

@@ -1146,6 +1146,7 @@ dependencies = [
  "mdbook-spec",
  "mdbook-trpl-listing",
  "mdbook-trpl-note",
+ "toml 0.5.11",
 ]
 
 [[package]]

src/tools/rustbook/Cargo.toml

@@ -13,6 +13,7 @@ mdbook-trpl-listing = { path = "../../doc/book/packages/mdbook-trpl-listing" }
 mdbook-trpl-note = { path = "../../doc/book/packages/mdbook-trpl-note" }
 mdbook-i18n-helpers = "0.3.3"
 mdbook-spec = { path = "../../doc/reference/mdbook-spec" }
+toml = "0.5.11"
 
 [dependencies.mdbook]
 version = "0.4.37"

src/tools/rustbook/src/main.rs

@@ -22,6 +22,11 @@ fn main() {
     .required(false)
     .value_parser(clap::value_parser!(String));
 
+    let n_arg = arg!(-n --"name" <NAME>
+"The book name")
+    .required(false)
+    .value_parser(clap::value_parser!(String));
+
     let root_arg = arg!(--"rust-root" <ROOT_DIR>
 "Path to the root of the rust source tree")
     .required(false)
@@ -56,6 +61,7 @@ fn main() {
                 .about("Build the book from the markdown files")
                 .arg(d_arg)
                 .arg(l_arg)
+                .arg(n_arg)
                 .arg(root_arg)
                 .arg(&dir_arg),
         )
@@ -121,8 +127,54 @@ pub fn build(args: &ArgMatches) -> Result3<()> {
         book.with_preprocessor(Spec::new(rust_root)?);
     }
 
+    let mut cleanup = Vec::new();
+    if let Some(rust_root) = args.get_one::<PathBuf>("rust-root") {
+        if let Some(name) = args.get_one::<String>("name") {
+            let translation_path = rust_root.join(format!("src/doc/translations/{name}"));
+            if translation_path.exists() {
+                let css_file = "theme/language-picker.css";
+                let js_file = "theme/language-picker.js";
+
+                let css_path = translation_path.join(css_file);
+                let js_path = translation_path.join(js_file);
+                let po_path = translation_path.join("po");
+
+                let theme_dir = book_dir.join("theme");
+                if !theme_dir.exists() {
+                    std::fs::create_dir(theme_dir)?;
+                }
+                let css_target = book_dir.join(css_file);
+                let js_target = book_dir.join(js_file);
+                std::fs::copy(css_path, &css_target)?;
+                std::fs::copy(js_path, &js_target)?;
+                cleanup.push(css_target);
+                cleanup.push(js_target);
+
+                let css_file: toml::Value = css_file.into();
+                let js_file: toml::Value = js_file.into();
+                let po_path: toml::Value = po_path.to_string_lossy().as_ref().into();
+
+                if let Some(additional_css) = book.config.get_mut("output.html.additional-css") {
+                    additional_css.as_array_mut().unwrap().push(css_file.into());
+                } else {
+                    book.config.set("output.html.additional-css", vec![css_file])?;
+                }
+                if let Some(additional_js) = book.config.get_mut("output.html.additional-js") {
+                    additional_js.as_array_mut().unwrap().push(js_file.into());
+                } else {
+                    book.config.set("output.html.additional-js", vec![js_file])?;
+                }
+                book.config.set("preprocessor.gettext.po-dir", po_path)?;
+            }
+        }
+    }
+
     book.build()?;
 
+    for file in cleanup {
+        std::fs::remove_file(file)?;
+    }
+
     Ok(())
 }