Add new tool to check HTML:

 * Make html-checker run by default on rust compiler docs as well
 * Ensure html-checker is run on CI
 * Lazify tidy binary presence check

2 files changed, 108 insertions, 0 deletions

diff --git a/src/tools/html-checker/Cargo.toml b/src/tools/html-checker/Cargo.toml
new file mode 100644
index 00000000000..fe35df823b6
--- /dev/null
+++ b/src/tools/html-checker/Cargo.toml
@@ -0,0 +1,12 @@
+[package]
+name = "html-checker"
+version = "0.1.0"
+authors = ["Guillaume Gomez <guillaume1.gomez@gmail.com>"]
+edition = "2018"
+
+[[bin]]
+name = "html-checker"
+path = "main.rs"
+
+[dependencies]
+walkdir = "2"
diff --git a/src/tools/html-checker/main.rs b/src/tools/html-checker/main.rs
new file mode 100644
index 00000000000..a93191191cc
--- /dev/null
+++ b/src/tools/html-checker/main.rs
@@ -0,0 +1,96 @@
+use std::env;
+use std::path::Path;
+use std::process::{Command, Output};
+
+fn check_html_file(file: &Path) -> usize {
+    let to_mute = &[
+        // "disabled" on <link> or "autocomplete" on <select> emit this warning
+        "PROPRIETARY_ATTRIBUTE",
+        // It complains when multiple in the same page link to the same anchor for some reason...
+        "ANCHOR_NOT_UNIQUE",
+        // If a <span> contains only HTML elements and no text, it complains about it.
+        "TRIM_EMPTY_ELEMENT",
+        // FIXME: the three next warnings are about <pre> elements which are not supposed to
+        //        contain HTML. The solution here would be to replace them with a <div> with
+        //        ""
+        "MISSING_ENDTAG_BEFORE",
+        "INSERTING_TAG",
+        "DISCARDING_UNEXPECTED",
+        // FIXME: mdbook repeats the name attribute on <input>. When the fix is merged upstream,
+        //        this warning can be used again.
+        "REPEATED_ATTRIBUTE",
+        // FIXME: mdbook uses "align" attribute on <td>, which is not allowed.
+        "MISMATCHED_ATTRIBUTE_WARN",
+        // FIXME: mdbook doesn't add "alt" attribute on images.
+        "MISSING_ATTRIBUTE",
+        // FIXME: mdbook doesn't escape `&` (in "&String" for example).
+        "UNKNOWN_ENTITY",
+        // Compiler docs have some inlined <style> in the markdown.
+        "MOVED_STYLE_TO_HEAD",
+    ];
+    let to_mute_s = to_mute.join(",");
+    let mut command = Command::new("tidy");
+    command
+        .arg("-errors")
+        .arg("-quiet")
+        .arg("--mute-id") // this option is useful in case we want to mute more warnings
+        .arg("yes")
+        .arg("--mute")
+        .arg(&to_mute_s)
+        .arg(file);
+
+    let Output { status, stderr, .. } = command.output().expect("failed to run tidy command");
+    if status.success() {
+        0
+    } else {
+        let stderr = String::from_utf8(stderr).expect("String::from_utf8 failed...");
+        if stderr.is_empty() && status.code() != Some(2) {
+            0
+        } else {
+            eprintln!(
+                "=> Errors for `{}` (error code: {}) <=",
+                file.display(),
+                status.code().unwrap_or(-1)
+            );
+            eprintln!("{}", stderr);
+            stderr.lines().count()
+        }
+    }
+}
+
+// Returns the number of files read and the number of errors.
+fn find_all_html_files(dir: &Path) -> (usize, usize) {
+    let mut files_read = 0;
+    let mut errors = 0;
+
+    for entry in walkdir::WalkDir::new(dir) {
+        let entry = entry.expect("failed to read file");
+        if !entry.file_type().is_file() {
+            continue;
+        }
+        let entry = entry.path();
+        if entry.extension().and_then(|s| s.to_str()) == Some("html") {
+            errors += check_html_file(&entry);
+            files_read += 1;
+        }
+    }
+    (files_read, errors)
+}
+
+fn main() -> Result<(), String> {
+    let args = env::args().collect::<Vec<_>>();
+    if args.len() != 2 {
+        return Err(format!("Usage: {} <doc folder>", args[0]));
+    }
+
+    println!("Running HTML checker...");
+
+    let (files_read, errors) = find_all_html_files(&Path::new(&args[1]));
+    println!("Done! Read {} files...", files_read);
+    if errors > 0 {
+        Err(format!("HTML check failed: {} errors", errors))
+    } else {
+        println!("No error found!");
+        Ok(())
+    }
+}