--- /dev/null
+use std::ffi::OsStr;
+use std::path::PathBuf;
+
+use regex::RegexSet;
+
+#[derive(Debug)]
+struct Message {
+ path: PathBuf,
+ bad_lines: Vec<String>,
+}
+
+impl Message {
+ fn new(path: PathBuf) -> Self {
+ let content: String = std::fs::read_to_string(&path).unwrap();
+ // we don't want the first letter after "error: ", "help: " ... to be capitalized
+ // also no puncutation (except for "?" ?) at the end of a line
+ let regex_set: RegexSet = RegexSet::new(&[
+ r"error: [A-Z]",
+ r"help: [A-Z]",
+ r"warning: [A-Z]",
+ r"note: [A-Z]",
+ r"try this: [A-Z]",
+ r"error: .*[.!]$",
+ r"help: .*[.!]$",
+ r"warning: .*[.!]$",
+ r"note: .*[.!]$",
+ r"try this: .*[.!]$",
+ ])
+ .unwrap();
+
+ // sometimes the first character is capitalized and it is legal (like in "C-like enum variants") or
+ // we want to ask a question ending in "?"
+ let exceptions_set: RegexSet = RegexSet::new(&[
+ r".*C-like enum variant discriminant is not portable to 32-bit targets",
+ r".*did you mean `unix`?",
+ r".*the arguments may be inverted...",
+ r".*Intel x86 assembly syntax used",
+ r".*AT&T x86 assembly syntax used",
+ r".*remove .*the return type...",
+ r"note: Clippy version: .*",
+ r"the compiler unexpectedly panicked. this is a bug.",
+ ])
+ .unwrap();
+
+ let bad_lines = content
+ .lines()
+ .filter(|line| regex_set.matches(line).matched_any())
+ // ignore exceptions
+ .filter(|line| !exceptions_set.matches(line).matched_any())
+ .map(ToOwned::to_owned)
+ .collect::<Vec<String>>();
+
+ Message { path, bad_lines }
+ }
+}
+
+#[test]
+fn lint_message_convention() {
+ // disable the test inside the rustc test suite
+ if option_env!("RUSTC_TEST_SUITE").is_some() {
+ return;
+ }
+
+ // make sure that lint messages:
+ // * are not capitalized
+ // * don't have puncuation at the end of the last sentence
+
+ // these directories have interesting tests
+ let test_dirs = ["ui", "ui-cargo", "ui-internal", "ui-toml"]
+ .iter()
+ .map(PathBuf::from)
+ .map(|p| {
+ let base = PathBuf::from("tests");
+ base.join(p)
+ });
+
+ // gather all .stderr files
+ let tests = test_dirs
+ .flat_map(|dir| {
+ std::fs::read_dir(dir)
+ .expect("failed to read dir")
+ .map(|direntry| direntry.unwrap().path())
+ })
+ .filter(|file| matches!(file.extension().map(OsStr::to_str), Some(Some("stderr"))));
+
+ // get all files that have any "bad lines" in them
+ let bad_tests: Vec<Message> = tests
+ .map(Message::new)
+ .filter(|message| !message.bad_lines.is_empty())
+ .collect();
+
+ bad_tests.iter().for_each(|message| {
+ eprintln!(
+ "error: the test '{}' contained the following nonconforming lines :",
+ message.path.display()
+ );
+ message.bad_lines.iter().for_each(|line| eprintln!("{}", line));
+ eprintln!("\n\n");
+ });
+
+ eprintln!(
+ "\n\n\nLint message should not start with a capital letter and should not have punctuation at the end of the message unless multiple sentences are needed."
+ );
+ eprintln!("Check out the rustc-dev-guide for more information:");
+ eprintln!("https://rustc-dev-guide.rust-lang.org/diagnostics.html#diagnostic-structure\n\n\n");
+
+ assert!(bad_tests.is_empty());
+}