Add default favicon for documentation

Author: GuillaumeGomez

src/librustdoc/html/layout.rs

@@ -191,7 +191,9 @@ pub fn render<T: fmt::Display, S: fmt::Display>(
     description = page.description,
     keywords = page.keywords,
     favicon   = if layout.favicon.is_empty() {
-        String::new()
+        format!(r#"<link rel="shortcut icon" href="{static_root_path}favicon{suffix}.ico">"#,
+                static_root_path=static_root_path,
+                suffix=page.resource_suffix)
     } else {
         format!(r#"<link rel="shortcut icon" href="{}">"#, layout.favicon)
     },

src/librustdoc/html/render.rs

@@ -793,6 +793,10 @@ fn write_shared(
         write(cx.dst.join(&format!("rust-logo{}.png", cx.shared.resource_suffix)),
               static_files::RUST_LOGO)?;
     }
+    if (*cx.shared).layout.favicon.is_empty() {
+        write(cx.dst.join(&format!("favicon{}.ico", cx.shared.resource_suffix)),
+              static_files::RUST_FAVICON)?;
+    }
     write(cx.dst.join(&format!("brush{}.svg", cx.shared.resource_suffix)),
           static_files::BRUSH_SVG)?;
     write(cx.dst.join(&format!("wheel{}.svg", cx.shared.resource_suffix)),
@@ -1999,8 +2003,6 @@ impl Context {
         themes.push(PathBuf::from("settings.css"));
         let mut layout = self.shared.layout.clone();
         layout.krate = String::new();
-        layout.logo = String::new();
-        layout.favicon = String::new();
         try_err!(layout::render(&mut w, &layout,
                                 &page, &sidebar, &settings,
                                 self.shared.css_file_extension.is_some(),

src/librustdoc/html/static/favicon.ico

@@ -53,6 +53,8 @@ pub static LICENSE_MIT: &'static [u8] = include_bytes!("static/LICENSE-MIT.txt")
 
 /// The contents of `rust-logo.png`, the default icon of the documentation.
 pub static RUST_LOGO: &'static [u8] = include_bytes!("static/rust-logo.png");
+/// The contents of `favicon.ico`, the default favicon of the documentation.
+pub static RUST_FAVICON: &'static [u8] = include_bytes!("static/favicon.ico");
 
 /// The built-in themes given to every documentation site.
 pub mod themes {