Switch fontawesome from font files to embedded SVG

Fixes rust-lang#790

The rationale for embedding the SVG files directly in the binary:

* avoid file I/O occurring in your Tera Filter, which would likely
  have complex knock-on effects when combined with `async`
* avoid complex error handling in your Tera Filter, which is the
  inevitable outcome of file I/O
* avoid having to carefully construct filesystem paths, with all
  the terrible possible outcomes and failure modes that come with
  that (using the infrastructure that the existing static file
  server uses is not an option, because it's not an HTTP request)
* I'm guessing it's faster to pull a string out of the binary's
  text section than it is to open a file for every request, though
  I have done no benchmarking to justify this wild speculation

The rationale for doing it in its own crate:

* we're not using any of docs.rs's file handling infrastructure
  anyway, so all the other stuff in its build.rs was just getting
  in the way while I coded up its codegen script
* it should be useful in other Rust web projects, regardless of
  the web framework they're using
* let's not force rustc to parse a 1.3MiB source file every time
  you change docs.rs; this seems like prime "separate translation
  unit" material

Cargo.toml

@@ -50,6 +50,7 @@ once_cell = { version = "1.4.0", features = ["parking_lot"] }
 base64 = "0.12.1"
 strum = { version = "0.18.0", features = ["derive"] }
 lol_html = "0.2"
+font-awesome-as-a-crate = { path = "crates/font-awesome-as-a-crate" }
 
 # Async
 tokio = { version = "0.2.22", features = ["rt-threaded"] }

README.md

@@ -220,18 +220,9 @@ cargo run -- queue add <CRATE> <VERSION>
 
 ### Updating vendored sources
 
-The instructions & links for updating Font Awesome can be found [on their website](https://fontawesome.com/how-to-use/on-the-web/using-with/sass). Similarly, Pure-CSS also [explains on theirs](https://purecss.io/start/).
+The instructions & links for updating Font Awesome can be found [on their website](https://fontawesome.com/how-to-use/on-the-web/advanced/svg-sprites). Similarly, Pure-CSS also [explains on theirs](https://purecss.io/start/).
 
 When updating Font Awesome, make sure to change `$fa-font-path` in `scss/_variables.scss` (it should be at the top of the file) to `../-/static`. This will point font awesome at the correct path from which to request font and icon resources.
-<!--
-    TODO: Whenever scss modules are avaliable, use [scss modules](https://sass-lang.com/documentation/at-rules/use#configuration)
-    instead of manually editing the `_variables.scss` file. Something like this should work:
-    ```scss
-    @use "fontawesome" with (
-        $fa-font-path: "../-/static"
-    );
-    ```
--->
 
 ### Contact
 

build.rs

@@ -18,7 +18,6 @@ fn main() {
     println!("cargo:rerun-if-changed=templates/menu.js");
     println!("cargo:rerun-if-changed=templates/index.js");
     println!("cargo:rerun-if-changed=vendor/");
-    println!("cargo:rerun-if-changed=vendor/fontawesome/scss/_variables.scss");
     // TODO: are these right?
     println!("cargo:rerun-if-changed=.git/HEAD");
     println!("cargo:rerun-if-changed=.git/index");
@@ -91,10 +90,7 @@ fn compile_sass() -> Result<(), Box<dyn Error>> {
     compile_sass_file(
         "vendored",
         "vendored",
-        &[
-            concat!(env!("CARGO_MANIFEST_DIR"), "/vendor/fontawesome/scss").to_owned(),
-            concat!(env!("CARGO_MANIFEST_DIR"), "/vendor/pure-css/css").to_owned(),
-        ],
+        &[concat!(env!("CARGO_MANIFEST_DIR"), "/vendor/pure-css/css").to_owned()],
     )?;
 
     Ok(())

crates/font-awesome-as-a-crate/.gitignore

@@ -0,0 +1,2 @@
+/target
+Cargo.lock

crates/font-awesome-as-a-crate/Cargo.toml

@@ -0,0 +1,10 @@
+[package]
+name = "font-awesome-as-a-crate"
+version = "0.1.2"
+# https://github.com/FortAwesome/Font-Awesome/blob/master/composer.json
+authors = ["Michael Howell <[email protected]>", "Travis Chase", "Dave Gandy", "Rob Madole", "Jory Raphael", "Geremia Taglialatela", "Brian Talbot", "Mike Wilkerson", "Fonticons Inc <[email protected]>"]
+edition = "2018"
+license = "CC-BY-4.0 AND MIT"
+description = "Font Awesome Free, packaged as a crate"
+repository = "https://github.com/rust-lang/docs.rs"
+

crates/font-awesome-as-a-crate/README.md

@@ -0,0 +1,5 @@
+# [Font Awesome Free](https://fontawesome.com/how-to-use/on-the-web/setup/hosting-font-awesome-yourself) SVG files as a crate
+
+This is not officially supported by Fonticons, Inc.
+If you have problems, [contact us](https://github.com/rust-lang/docs.rs), not them.
+

crates/font-awesome-as-a-crate/build.rs

@@ -0,0 +1,54 @@
+use std::{
+    env,
+    fs::{read_dir, File},
+    io::{Read, Write},
+    path::Path,
+};
+
+fn main() {
+    println!("cargo:rustc-cfg=font_awesome_out_dir");
+    write_fontawesome_sprite();
+}
+
+fn write_fontawesome_sprite() {
+    let dest_path = Path::new(&env::var("OUT_DIR").unwrap()).join("fontawesome.rs");
+    let mut dest_file = File::create(&dest_path).unwrap();
+    dest_file
+        .write_all(b"fn fontawesome_svg(dir:&str,file:&str)->&'static str{match(dir,file){")
+        .expect("fontawesome fn write");
+    for dirname in &["brands", "regular", "solid"] {
+        let dir = read_dir(Path::new("fontawesome-free-5.14.0-web/svgs").join(dirname)).unwrap();
+        let mut data = String::new();
+        for file in dir {
+            let file = file.expect("fontawesome directory access");
+            let filename = file
+                .file_name()
+                .into_string()
+                .expect("fontawesome filenames are unicode");
+            let mut file = File::open(file.path()).expect("fontawesome file access");
+            data.clear();
+            file.read_to_string(&mut data)
+                .expect("fontawesome file read");
+            // if this assert goes off, add more hashes here and in the format! below
+            assert!(
+                data.find("###").is_none(),
+                "file {} breaks raw string",
+                filename,
+            );
+            dest_file
+                .write_all(
+                    format!(
+                        r####"("{dirname}","{filename}")=>r###"{data}"###,"####,
+                        data = data,
+                        dirname = dirname,
+                        filename = filename.replace(".svg", ""),
+                    )
+                    .as_bytes(),
+                )
+                .expect("write fontawesome file");
+        }
+    }
+    dest_file
+        .write_all(b"_=>\"\"}}")
+        .expect("fontawesome fn write");
+}

crates/font-awesome-as-a-crate/fontawesome-free-5.14.0-web/VENDOR.md

@@ -0,0 +1,3 @@
+The svgs folder was downloaded from https://fontawesome.com/how-to-use/on-the-web/setup/hosting-font-awesome-yourself
+The rest of fontawesome was just deleted; this means that the font license and MIT license are not applicable, just the copyright license on the icon files themselves.
+