Merging upstream version 1.70.0+dfsg1.

Signed-off-by: Daniel Baumann <daniel.baumann@progress-linux.org>

17 files changed, 363 insertions, 283 deletions

diff --git a/src/tools/tidy/Cargo.toml b/src/tools/tidy/Cargo.toml
index cdf1dd366..8c6b1eb22 100644
--- a/src/tools/tidy/Cargo.toml
+++ b/src/tools/tidy/Cargo.toml
@@ -5,7 +5,7 @@ edition = "2021"
 autobins = false
 
 [dependencies]
-cargo_metadata = "0.14"
+cargo_metadata = "0.15"
 cargo-platform = "0.1.2"
 regex = "1"
 miropt-test-tools = { path = "../miropt-test-tools" }
diff --git a/src/tools/tidy/src/alphabetical.rs b/src/tools/tidy/src/alphabetical.rs
index f913f6cde..fdc411c89 100644
--- a/src/tools/tidy/src/alphabetical.rs
+++ b/src/tools/tidy/src/alphabetical.rs
@@ -95,7 +95,7 @@ fn check_section<'a>(
 }
 
 pub fn check(path: &Path, bad: &mut bool) {
-    walk(path, &mut filter_dirs, &mut |entry, contents| {
+    walk(path, |path, _is_dir| filter_dirs(path), &mut |entry, contents| {
         let file = &entry.path().display();
 
         let mut lines = contents.lines().enumerate().peekable();
diff --git a/src/tools/tidy/src/bins.rs b/src/tools/tidy/src/bins.rs
index b898f20a5..197e9a996 100644
--- a/src/tools/tidy/src/bins.rs
+++ b/src/tools/tidy/src/bins.rs
@@ -57,8 +57,8 @@ mod os_impl {
             match fs::File::create(&path) {
                 Ok(file) => {
                     let exec = is_executable(&path).unwrap_or(false);
-                    std::mem::drop(file);
-                    std::fs::remove_file(&path).expect("Deleted temp file");
+                    drop(file);
+                    fs::remove_file(&path).expect("Deleted temp file");
                     // If the file is executable, then we assume that this
                     // filesystem does not track executability, so skip this check.
                     return if exec { Unsupported } else { Supported };
@@ -101,23 +101,11 @@ mod os_impl {
 
         const ALLOWED: &[&str] = &["configure", "x"];
 
+        // FIXME: we don't need to look at all binaries, only files that have been modified in this branch
+        // (e.g. using `git ls-files`).
         walk_no_read(
-            path,
-            &mut |path| {
-                filter_dirs(path)
-                    || path.ends_with("src/etc")
-                    // This is a list of directories that we almost certainly
-                    // don't need to walk. A future PR will likely want to
-                    // remove these in favor of crate::walk_no_read using git
-                    // ls-files to discover the paths we should check, which
-                    // would naturally ignore all of these directories. It's
-                    // also likely faster than walking the directory tree
-                    // directly (since git is just reading from a couple files
-                    // to produce the results).
-                    || path.ends_with("target")
-                    || path.ends_with("build")
-                    || path.ends_with(".git")
-            },
+            &[path],
+            |path, _is_dir| filter_dirs(path) || path.ends_with("src/etc"),
             &mut |entry| {
                 let file = entry.path();
                 let extension = file.extension();
diff --git a/src/tools/tidy/src/debug_artifacts.rs b/src/tools/tidy/src/debug_artifacts.rs
index 0dd9c1e16..582014d50 100644
--- a/src/tools/tidy/src/debug_artifacts.rs
+++ b/src/tools/tidy/src/debug_artifacts.rs
@@ -1,22 +1,26 @@
 //! Tidy check to prevent creation of unnecessary debug artifacts while running tests.
 
-use crate::walk::{filter_dirs, walk};
+use crate::walk::{filter_dirs, filter_not_rust, walk};
 use std::path::Path;
 
 const GRAPHVIZ_POSTFLOW_MSG: &str = "`borrowck_graphviz_postflow` attribute in test";
 
 pub fn check(test_dir: &Path, bad: &mut bool) {
-    walk(test_dir, &mut filter_dirs, &mut |entry, contents| {
-        let filename = entry.path();
-        let is_rust = filename.extension().map_or(false, |ext| ext == "rs");
-        if !is_rust {
-            return;
-        }
-
-        for (i, line) in contents.lines().enumerate() {
-            if line.contains("borrowck_graphviz_postflow") {
-                tidy_error!(bad, "{}:{}: {}", filename.display(), i + 1, GRAPHVIZ_POSTFLOW_MSG);
+    walk(
+        test_dir,
+        |path, _is_dir| filter_dirs(path) || filter_not_rust(path),
+        &mut |entry, contents| {
+            for (i, line) in contents.lines().enumerate() {
+                if line.contains("borrowck_graphviz_postflow") {
+                    tidy_error!(
+                        bad,
+                        "{}:{}: {}",
+                        entry.path().display(),
+                        i + 1,
+                        GRAPHVIZ_POSTFLOW_MSG
+                    );
+                }
             }
-        }
-    });
+        },
+    );
 }
diff --git a/src/tools/tidy/src/deps.rs b/src/tools/tidy/src/deps.rs
index bddfdcfaf..a9eb6c8d0 100644
--- a/src/tools/tidy/src/deps.rs
+++ b/src/tools/tidy/src/deps.rs
@@ -42,13 +42,16 @@ const EXCEPTIONS: &[(&str, &str)] = &[
     ("bitmaps", "MPL-2.0+"),                                 // cargo via im-rc
     ("fiat-crypto", "MIT OR Apache-2.0 OR BSD-1-Clause"),    // cargo via pasetors
     ("subtle", "BSD-3-Clause"),                              // cargo via pasetors
+    ("dunce", "CC0-1.0 OR MIT-0"),                           // cargo via gix (and dev dependency)
+    ("imara-diff", "Apache-2.0"),                            // cargo via gix
+    ("sha1_smol", "BSD-3-Clause"),                           // cargo via gix
+    ("unicode-bom", "Apache-2.0"),                           // cargo via gix
     ("instant", "BSD-3-Clause"), // rustc_driver/tracing-subscriber/parking_lot
     ("snap", "BSD-3-Clause"),    // rustc
     ("fluent-langneg", "Apache-2.0"), // rustc (fluent translations)
     ("self_cell", "Apache-2.0"), // rustc (fluent translations)
     // FIXME: this dependency violates the documentation comment above:
     ("fortanix-sgx-abi", "MPL-2.0"), // libstd but only for `sgx` target
-    ("dunce", "CC0-1.0"),            // cargo (dev dependency)
     ("similar", "Apache-2.0"),       // cargo (dev dependency)
     ("normalize-line-endings", "Apache-2.0"), // cargo (dev dependency)
     ("dissimilar", "Apache-2.0"),    // rustdoc, rustc_lexer (few tests) via expect-test, (dev deps)
@@ -257,6 +260,7 @@ const PERMITTED_RUSTC_DEPENDENCIES: &[&str] = &[
     "valuable",
     "version_check",
     "wasi",
+    "windows",
     "winapi",
     "winapi-i686-pc-windows-gnu",
     "winapi-util",
diff --git a/src/tools/tidy/src/edition.rs b/src/tools/tidy/src/edition.rs
index 8172e3d29..f28f677e0 100644
--- a/src/tools/tidy/src/edition.rs
+++ b/src/tools/tidy/src/edition.rs
@@ -9,27 +9,20 @@ fn is_edition_2021(mut line: &str) -> bool {
 }
 
 pub fn check(path: &Path, bad: &mut bool) {
-    walk(
-        path,
-        &mut |path| {
-            filter_dirs(path)
-                || (path.ends_with("tests") && path.join("COMPILER_TESTS.md").exists())
-        },
-        &mut |entry, contents| {
-            let file = entry.path();
-            let filename = file.file_name().unwrap();
-            if filename != "Cargo.toml" {
-                return;
-            }
+    walk(path, |path, _is_dir| filter_dirs(path), &mut |entry, contents| {
+        let file = entry.path();
+        let filename = file.file_name().unwrap();
+        if filename != "Cargo.toml" {
+            return;
+        }
 
-            let is_2021 = contents.lines().any(is_edition_2021);
-            if !is_2021 {
-                tidy_error!(
-                    bad,
-                    "{} doesn't have `edition = \"2021\"` on a separate line",
-                    file.display()
-                );
-            }
-        },
-    );
+        let is_2021 = contents.lines().any(is_edition_2021);
+        if !is_2021 {
+            tidy_error!(
+                bad,
+                "{} doesn't have `edition = \"2021\"` on a separate line",
+                file.display()
+            );
+        }
+    });
 }
diff --git a/src/tools/tidy/src/error_codes.rs b/src/tools/tidy/src/error_codes.rs
index c60caa0d4..417ace58c 100644
--- a/src/tools/tidy/src/error_codes.rs
+++ b/src/tools/tidy/src/error_codes.rs
@@ -46,8 +46,10 @@ pub fn check(root_path: &Path, search_paths: &[&Path], verbose: bool, bad: &mut
 
     // Stage 1: create list
     let error_codes = extract_error_codes(root_path, &mut errors);
-    println!("Found {} error codes", error_codes.len());
-    println!("Highest error code: `{}`", error_codes.iter().max().unwrap());
+    if verbose {
+        println!("Found {} error codes", error_codes.len());
+        println!("Highest error code: `{}`", error_codes.iter().max().unwrap());
+    }
 
     // Stage 2: check list has docs
     let no_longer_emitted = check_error_codes_docs(root_path, &error_codes, &mut errors, verbose);
@@ -127,7 +129,7 @@ fn check_error_codes_docs(
 
     let mut no_longer_emitted_codes = Vec::new();
 
-    walk(&docs_path, &mut |_| false, &mut |entry, contents| {
+    walk(&docs_path, |_, _| false, &mut |entry, contents| {
         let path = entry.path();
 
         // Error if the file isn't markdown.
@@ -319,7 +321,7 @@ fn check_error_codes_used(
 
     let mut found_codes = Vec::new();
 
-    walk_many(search_paths, &mut filter_dirs, &mut |entry, contents| {
+    walk_many(search_paths, |path, _is_dir| filter_dirs(path), &mut |entry, contents| {
         let path = entry.path();
 
         // Return early if we aren't looking at a source file.
diff --git a/src/tools/tidy/src/features.rs b/src/tools/tidy/src/features.rs
index af92e6eb8..2fd4c797b 100644
--- a/src/tools/tidy/src/features.rs
+++ b/src/tools/tidy/src/features.rs
@@ -9,8 +9,9 @@
 //! * All unstable lang features have tests to ensure they are actually unstable.
 //! * Language features in a group are sorted by feature name.
 
-use crate::walk::{filter_dirs, walk, walk_many};
+use crate::walk::{filter_dirs, filter_not_rust, walk, walk_many};
 use std::collections::hash_map::{Entry, HashMap};
+use std::ffi::OsStr;
 use std::fmt;
 use std::fs;
 use std::num::NonZeroU32;
@@ -101,17 +102,15 @@ pub fn check(
             &tests_path.join("rustdoc-ui"),
             &tests_path.join("rustdoc"),
         ],
-        &mut filter_dirs,
+        |path, _is_dir| {
+            filter_dirs(path)
+                || filter_not_rust(path)
+                || path.file_name() == Some(OsStr::new("features.rs"))
+                || path.file_name() == Some(OsStr::new("diagnostic_list.rs"))
+        },
         &mut |entry, contents| {
             let file = entry.path();
             let filename = file.file_name().unwrap().to_string_lossy();
-            if !filename.ends_with(".rs")
-                || filename == "features.rs"
-                || filename == "diagnostic_list.rs"
-            {
-                return;
-            }
-
             let filen_underscore = filename.replace('-', "_").replace(".rs", "");
             let filename_is_gate_test = test_filen_gate(&filen_underscore, &mut features);
 
@@ -219,8 +218,6 @@ pub fn check(
         for line in lines {
             println!("* {line}");
         }
-    } else {
-        println!("* {} features", features.len());
     }
 
     CollectedFeatures { lib: lib_features, lang: features }
@@ -477,11 +474,11 @@ fn get_and_check_lib_features(
 
 fn map_lib_features(
     base_src_path: &Path,
-    mf: &mut dyn FnMut(Result<(&str, Feature), &str>, &Path, usize),
+    mf: &mut (dyn Send + Sync + FnMut(Result<(&str, Feature), &str>, &Path, usize)),
 ) {
     walk(
         base_src_path,
-        &mut |path| filter_dirs(path) || path.ends_with("tests"),
+        |path, _is_dir| filter_dirs(path) || path.ends_with("tests"),
         &mut |entry, contents| {
             let file = entry.path();
             let filename = file.file_name().unwrap().to_string_lossy();
diff --git a/src/tools/tidy/src/main.rs b/src/tools/tidy/src/main.rs
index 505f9d724..f59406c40 100644
--- a/src/tools/tidy/src/main.rs
+++ b/src/tools/tidy/src/main.rs
@@ -13,7 +13,7 @@ use std::path::PathBuf;
 use std::process;
 use std::str::FromStr;
 use std::sync::atomic::{AtomicBool, Ordering};
-use std::thread::{scope, ScopedJoinHandle};
+use std::thread::{self, scope, ScopedJoinHandle};
 
 fn main() {
     let root_path: PathBuf = env::args_os().nth(1).expect("need path to root of repo").into();
@@ -55,16 +55,28 @@ fn main() {
             VecDeque::with_capacity(concurrency.get());
 
         macro_rules! check {
-            ($p:ident $(, $args:expr)* ) => {
+            ($p:ident) => {
+                check!(@ $p, name=format!("{}", stringify!($p)));
+            };
+            ($p:ident, $path:expr $(, $args:expr)* ) => {
+                let shortened = $path.strip_prefix(&root_path).unwrap();
+                let name = if shortened == std::path::Path::new("") {
+                    format!("{} (.)", stringify!($p))
+                } else {
+                    format!("{} ({})", stringify!($p), shortened.display())
+                };
+                check!(@ $p, name=name, $path $(,$args)*);
+            };
+            (@ $p:ident, name=$name:expr $(, $args:expr)* ) => {
                 drain_handles(&mut handles);
 
-                let handle = s.spawn(|| {
+                let handle = thread::Builder::new().name($name).spawn_scoped(s, || {
                     let mut flag = false;
                     $p::check($($args, )* &mut flag);
                     if (flag) {
                         bad.store(true, Ordering::Relaxed);
                     }
-                });
+                }).unwrap();
                 handles.push_back(handle);
             }
         }
@@ -91,7 +103,6 @@ fn main() {
 
         // Checks that need to be done for both the compiler and std libraries.
         check!(unit_tests, &src_path);
-        check!(unit_tests, &tests_path);
         check!(unit_tests, &compiler_path);
         check!(unit_tests, &library_path);
 
@@ -107,10 +118,8 @@ fn main() {
         check!(edition, &src_path);
         check!(edition, &compiler_path);
         check!(edition, &library_path);
-        check!(edition, &tests_path);
 
         check!(alphabetical, &src_path);
-        check!(alphabetical, &tests_path);
         check!(alphabetical, &compiler_path);
         check!(alphabetical, &library_path);
 
diff --git a/src/tools/tidy/src/mir_opt_tests.rs b/src/tools/tidy/src/mir_opt_tests.rs
index 2a9dcac2e..2f6918510 100644
--- a/src/tools/tidy/src/mir_opt_tests.rs
+++ b/src/tools/tidy/src/mir_opt_tests.rs
@@ -3,19 +3,24 @@
 use std::collections::HashSet;
 use std::path::{Path, PathBuf};
 
+use crate::walk::walk_no_read;
+
 fn check_unused_files(path: &Path, bless: bool, bad: &mut bool) {
     let mut rs_files = Vec::<PathBuf>::new();
     let mut output_files = HashSet::<PathBuf>::new();
-    let files = walkdir::WalkDir::new(&path.join("mir-opt")).into_iter();
 
-    for file in files.filter_map(Result::ok).filter(|e| e.file_type().is_file()) {
-        let filepath = file.path();
-        if filepath.extension() == Some("rs".as_ref()) {
-            rs_files.push(filepath.to_owned());
-        } else {
-            output_files.insert(filepath.to_owned());
-        }
-    }
+    walk_no_read(
+        &[&path.join("mir-opt")],
+        |path, _is_dir| path.file_name() == Some("README.md".as_ref()),
+        &mut |file| {
+            let filepath = file.path();
+            if filepath.extension() == Some("rs".as_ref()) {
+                rs_files.push(filepath.to_owned());
+            } else {
+                output_files.insert(filepath.to_owned());
+            }
+        },
+    );
 
     for file in rs_files {
         for bw in [32, 64] {
@@ -26,16 +31,14 @@ fn check_unused_files(path: &Path, bless: bool, bad: &mut bool) {
     }
 
     for extra in output_files {
-        if extra.file_name() != Some("README.md".as_ref()) {
-            if !bless {
-                tidy_error!(
-                    bad,
-                    "the following output file is not associated with any mir-opt test, you can remove it: {}",
-                    extra.display()
-                );
-            } else {
-                let _ = std::fs::remove_file(extra);
-            }
+        if !bless {
+            tidy_error!(
+                bad,
+                "the following output file is not associated with any mir-opt test, you can remove it: {}",
+                extra.display()
+            );
+        } else {
+            let _ = std::fs::remove_file(extra);
         }
     }
 }
diff --git a/src/tools/tidy/src/pal.rs b/src/tools/tidy/src/pal.rs
index f4592fdcf..6fd41e833 100644
--- a/src/tools/tidy/src/pal.rs
+++ b/src/tools/tidy/src/pal.rs
@@ -31,7 +31,6 @@
 //! this in the long term.
 
 use crate::walk::{filter_dirs, walk};
-use std::iter::Iterator;
 use std::path::Path;
 
 // Paths that may contain platform-specific code.
@@ -59,7 +58,6 @@ const EXCEPTION_PATHS: &[&str] = &[
     "library/std/src/path.rs",
     "library/std/src/sys_common", // Should only contain abstractions over platforms
     "library/std/src/net/test.rs", // Utility helpers for tests
-    "library/std/src/panic.rs",   // fuchsia-specific panic backtrace handling
     "library/std/src/personality.rs",
     "library/std/src/personality/",
 ];
@@ -68,7 +66,7 @@ pub fn check(path: &Path, bad: &mut bool) {
     // Sanity check that the complex parsing here works.
     let mut saw_target_arch = false;
     let mut saw_cfg_bang = false;
-    walk(path, &mut filter_dirs, &mut |entry, contents| {
+    walk(path, |path, _is_dir| filter_dirs(path), &mut |entry, contents| {
         let file = entry.path();
         let filestr = file.to_string_lossy().replace("\\", "/");
         if !filestr.ends_with(".rs") {
@@ -128,6 +126,7 @@ fn check_cfgs(
             || cfg.contains("target_env")
             || cfg.contains("target_abi")
             || cfg.contains("target_vendor")
+            || cfg.contains("target_family")
             || cfg.contains("unix")
             || cfg.contains("windows");
 
diff --git a/src/tools/tidy/src/rustdoc_gui_tests.rs b/src/tools/tidy/src/rustdoc_gui_tests.rs
index feb513df3..91776bc98 100644
--- a/src/tools/tidy/src/rustdoc_gui_tests.rs
+++ b/src/tools/tidy/src/rustdoc_gui_tests.rs
@@ -5,10 +5,7 @@ use std::path::Path;
 pub fn check(path: &Path, bad: &mut bool) {
     crate::walk::walk(
         &path.join("rustdoc-gui"),
-        &mut |p| {
-            // If there is no extension, it's very likely a folder and we want to go into it.
-            p.extension().map(|e| e != "goml").unwrap_or(false)
-        },
+        |p, is_dir| !is_dir && p.extension().map_or(true, |e| e != "goml"),
         &mut |entry, content| {
             for line in content.lines() {
                 if !line.starts_with("// ") {
diff --git a/src/tools/tidy/src/style.rs b/src/tools/tidy/src/style.rs
index 6a0855405..a2012db90 100644
--- a/src/tools/tidy/src/style.rs
+++ b/src/tools/tidy/src/style.rs
@@ -19,7 +19,7 @@
 
 use crate::walk::{filter_dirs, walk};
 use regex::{Regex, RegexSet};
-use std::path::Path;
+use std::{ffi::OsStr, path::Path};
 
 /// Error code markdown is restricted to 80 columns because they can be
 /// displayed on the console with --example.
@@ -171,9 +171,9 @@ fn contains_ignore_directive(can_contain: bool, contents: &str, check: &str) ->
 }
 
 macro_rules! suppressible_tidy_err {
-    ($err:ident, $skip:ident, $msg:expr) => {
+    ($err:ident, $skip:ident, $msg:literal) => {
         if let Directive::Deny = $skip {
-            $err($msg);
+            $err(&format!($msg));
         } else {
             $skip = Directive::Ignore(true);
         }
@@ -227,22 +227,41 @@ fn is_unexplained_ignore(extension: &str, line: &str) -> bool {
 }
 
 pub fn check(path: &Path, bad: &mut bool) {
-    fn skip(path: &Path) -> bool {
-        filter_dirs(path) || skip_markdown_path(path)
+    fn skip(path: &Path, is_dir: bool) -> bool {
+        if path.file_name().map_or(false, |name| name.to_string_lossy().starts_with(".#")) {
+            // vim or emacs temporary file
+            return true;
+        }
+
+        if filter_dirs(path) || skip_markdown_path(path) {
+            return true;
+        }
+
+        // Don't check extensions for directories
+        if is_dir {
+            return false;
+        }
+
+        let extensions = ["rs", "py", "js", "sh", "c", "cpp", "h", "md", "css", "ftl", "goml"];
+
+        // NB: don't skip paths without extensions (or else we'll skip all directories and will only check top level files)
+        if path.extension().map_or(true, |ext| !extensions.iter().any(|e| ext == OsStr::new(e))) {
+            return true;
+        }
+
+        // We only check CSS files in rustdoc.
+        path.extension().map_or(false, |e| e == "css") && !is_in(path, "src", "librustdoc")
     }
+
     let problematic_consts_strings: Vec<String> = (PROBLEMATIC_CONSTS.iter().map(u32::to_string))
         .chain(PROBLEMATIC_CONSTS.iter().map(|v| format!("{:x}", v)))
         .chain(PROBLEMATIC_CONSTS.iter().map(|v| format!("{:X}", v)))
         .collect();
     let problematic_regex = RegexSet::new(problematic_consts_strings.as_slice()).unwrap();
-    walk(path, &mut skip, &mut |entry, contents| {
+
+    walk(path, skip, &mut |entry, contents| {
         let file = entry.path();
         let filename = file.file_name().unwrap().to_string_lossy();
-        let extensions =
-            [".rs", ".py", ".js", ".sh", ".c", ".cpp", ".h", ".md", ".css", ".ftl", ".goml"];
-        if extensions.iter().all(|e| !filename.ends_with(e)) || filename.starts_with(".#") {
-            return;
-        }
 
         let is_style_file = filename.ends_with(".css");
         let under_rustfmt = filename.ends_with(".rs") &&
@@ -253,11 +272,6 @@ pub fn check(path: &Path, bad: &mut bool) {
                     a.ends_with("src/doc/book")
             });
 
-        if is_style_file && !is_in(file, "src", "librustdoc") {
-            // We only check CSS files in rustdoc.
-            return;
-        }
-
         if contents.is_empty() {
             tidy_error!(bad, "{}: empty file", file.display());
         }
@@ -300,10 +314,13 @@ pub fn check(path: &Path, bad: &mut bool) {
             contains_ignore_directive(can_contain, &contents, "leading-newlines");
         let mut skip_copyright = contains_ignore_directive(can_contain, &contents, "copyright");
         let mut skip_dbg = contains_ignore_directive(can_contain, &contents, "dbg");
+        let mut skip_odd_backticks =
+            contains_ignore_directive(can_contain, &contents, "odd-backticks");
         let mut leading_new_lines = false;
         let mut trailing_new_lines = 0;
         let mut lines = 0;
         let mut last_safety_comment = false;
+        let mut comment_block: Option<(usize, usize)> = None;
         let is_test = file.components().any(|c| c.as_os_str() == "tests");
         // scanning the whole file for multiple needles at once is more efficient than
         // executing lines times needles separate searches.
@@ -351,7 +368,7 @@ pub fn check(path: &Path, bad: &mut bool) {
                 suppressible_tidy_err!(
                     err,
                     skip_line_length,
-                    &format!("line longer than {max_columns} chars")
+                    "line longer than {max_columns} chars"
                 );
             }
             if !is_style_file && line.contains('\t') {
@@ -415,15 +432,55 @@ pub fn check(path: &Path, bad: &mut bool) {
 
             // For now only enforce in compiler
             let is_compiler = || file.components().any(|c| c.as_os_str() == "compiler");
-            if is_compiler()
-                && line.contains("//")
-                && line
-                    .chars()
-                    .collect::<Vec<_>>()
-                    .windows(4)
-                    .any(|cs| matches!(cs, ['.', ' ', ' ', last] if last.is_alphabetic()))
-            {
-                err(DOUBLE_SPACE_AFTER_DOT)
+
+            if is_compiler() {
+                if line.contains("//")
+                    && line
+                        .chars()
+                        .collect::<Vec<_>>()
+                        .windows(4)
+                        .any(|cs| matches!(cs, ['.', ' ', ' ', last] if last.is_alphabetic()))
+                {
+                    err(DOUBLE_SPACE_AFTER_DOT)
+                }
+
+                if filename.ends_with(".ftl") {
+                    let line_backticks = trimmed.chars().filter(|ch| *ch == '`').count();
+                    if line_backticks % 2 == 1 {
+                        suppressible_tidy_err!(err, skip_odd_backticks, "odd number of backticks");
+                    }
+                } else if trimmed.contains("//") {
+                    let (start_line, mut backtick_count) = comment_block.unwrap_or((i + 1, 0));
+                    let line_backticks = trimmed.chars().filter(|ch| *ch == '`').count();
+                    let comment_text = trimmed.split("//").nth(1).unwrap();
+                    // This check ensures that we don't lint for code that has `//` in a string literal
+                    if line_backticks % 2 == 1 {
+                        backtick_count += comment_text.chars().filter(|ch| *ch == '`').count();
+                    }
+                    comment_block = Some((start_line, backtick_count));
+                } else {
+                    if let Some((start_line, backtick_count)) = comment_block.take() {
+                        if backtick_count % 2 == 1 {
+                            let mut err = |msg: &str| {
+                                tidy_error!(bad, "{}:{start_line}: {msg}", file.display());
+                            };
+                            let block_len = (i + 1) - start_line;
+                            if block_len == 1 {
+                                suppressible_tidy_err!(
+                                    err,
+                                    skip_odd_backticks,
+                                    "comment with odd number of backticks"
+                                );
+                            } else {
+                                suppressible_tidy_err!(
+                                    err,
+                                    skip_odd_backticks,
+                                    "{block_len}-line comment block with odd number of backticks"
+                                );
+                            }
+                        }
+                    }
+                }
             }
         }
         if leading_new_lines {
@@ -441,7 +498,7 @@ pub fn check(path: &Path, bad: &mut bool) {
             n => suppressible_tidy_err!(
                 err,
                 skip_trailing_newlines,
-                &format!("too many trailing newlines ({n})")
+                "too many trailing newlines ({n})"
             ),
         };
         if lines > LINES {
diff --git a/src/tools/tidy/src/target_specific_tests.rs b/src/tools/tidy/src/target_specific_tests.rs
index d7a157672..de022be28 100644
--- a/src/tools/tidy/src/target_specific_tests.rs
+++ b/src/tools/tidy/src/target_specific_tests.rs
@@ -4,6 +4,8 @@
 use std::collections::BTreeMap;
 use std::path::Path;
 
+use crate::walk::filter_not_rust;
+
 const COMMENT: &str = "//";
 const LLVM_COMPONENTS_HEADER: &str = "needs-llvm-components:";
 const COMPILE_FLAGS_HEADER: &str = "compile-flags:";
@@ -35,61 +37,57 @@ struct RevisionInfo<'a> {
 }
 
 pub fn check(path: &Path, bad: &mut bool) {
-    crate::walk::walk(
-        path,
-        &mut |path| path.extension().map(|p| p == "rs") == Some(false),
-        &mut |entry, content| {
-            let file = entry.path().display();
-            let mut header_map = BTreeMap::new();
-            iter_header(content, &mut |cfg, directive| {
-                if let Some(value) = directive.strip_prefix(LLVM_COMPONENTS_HEADER) {
-                    let info = header_map.entry(cfg).or_insert(RevisionInfo::default());
-                    let comp_vec = info.llvm_components.get_or_insert(Vec::new());
-                    for component in value.split(' ') {
-                        let component = component.trim();
-                        if !component.is_empty() {
-                            comp_vec.push(component);
-                        }
-                    }
-                } else if directive.starts_with(COMPILE_FLAGS_HEADER) {
-                    let compile_flags = &directive[COMPILE_FLAGS_HEADER.len()..];
-                    if let Some((_, v)) = compile_flags.split_once("--target") {
-                        if let Some((arch, _)) =
-                            v.trim_start_matches(|c| c == ' ' || c == '=').split_once("-")
-                        {
-                            let info = header_map.entry(cfg).or_insert(RevisionInfo::default());
-                            info.target_arch.replace(arch);
-                        } else {
-                            eprintln!("{file}: seems to have a malformed --target value");
-                            *bad = true;
-                        }
+    crate::walk::walk(path, |path, _is_dir| filter_not_rust(path), &mut |entry, content| {
+        let file = entry.path().display();
+        let mut header_map = BTreeMap::new();
+        iter_header(content, &mut |cfg, directive| {
+            if let Some(value) = directive.strip_prefix(LLVM_COMPONENTS_HEADER) {
+                let info = header_map.entry(cfg).or_insert(RevisionInfo::default());
+                let comp_vec = info.llvm_components.get_or_insert(Vec::new());
+                for component in value.split(' ') {
+                    let component = component.trim();
+                    if !component.is_empty() {
+                        comp_vec.push(component);
                     }
                 }
-            });
-            for (rev, RevisionInfo { target_arch, llvm_components }) in &header_map {
-                let rev = rev.unwrap_or("[unspecified]");
-                match (target_arch, llvm_components) {
-                    (None, None) => {}
-                    (Some(_), None) => {
-                        eprintln!(
-                            "{}: revision {} should specify `{}` as it has `--target` set",
-                            file, rev, LLVM_COMPONENTS_HEADER
-                        );
+            } else if directive.starts_with(COMPILE_FLAGS_HEADER) {
+                let compile_flags = &directive[COMPILE_FLAGS_HEADER.len()..];
+                if let Some((_, v)) = compile_flags.split_once("--target") {
+                    if let Some((arch, _)) =
+                        v.trim_start_matches(|c| c == ' ' || c == '=').split_once("-")
+                    {
+                        let info = header_map.entry(cfg).or_insert(RevisionInfo::default());
+                        info.target_arch.replace(arch);
+                    } else {
+                        eprintln!("{file}: seems to have a malformed --target value");
                         *bad = true;
                     }
-                    (None, Some(_)) => {
-                        eprintln!(
-                            "{}: revision {} should not specify `{}` as it doesn't need `--target`",
-                            file, rev, LLVM_COMPONENTS_HEADER
-                        );
-                        *bad = true;
-                    }
-                    (Some(_), Some(_)) => {
-                        // FIXME: check specified components against the target architectures we
-                        // gathered.
-                    }
                 }
             }
-        },
-    );
+        });
+        for (rev, RevisionInfo { target_arch, llvm_components }) in &header_map {
+            let rev = rev.unwrap_or("[unspecified]");
+            match (target_arch, llvm_components) {
+                (None, None) => {}
+                (Some(_), None) => {
+                    eprintln!(
+                        "{}: revision {} should specify `{}` as it has `--target` set",
+                        file, rev, LLVM_COMPONENTS_HEADER
+                    );
+                    *bad = true;
+                }
+                (None, Some(_)) => {
+                    eprintln!(
+                        "{}: revision {} should not specify `{}` as it doesn't need `--target`",
+                        file, rev, LLVM_COMPONENTS_HEADER
+                    );
+                    *bad = true;
+                }
+                (Some(_), Some(_)) => {
+                    // FIXME: check specified components against the target architectures we
+                    // gathered.
+                }
+            }
+        }
+    });
 }
diff --git a/src/tools/tidy/src/ui_tests.rs b/src/tools/tidy/src/ui_tests.rs
index 409f75631..29664c854 100644
--- a/src/tools/tidy/src/ui_tests.rs
+++ b/src/tools/tidy/src/ui_tests.rs
@@ -3,87 +3,99 @@
 //! - there are no stray `.stderr` files
 
 use ignore::Walk;
-use ignore::WalkBuilder;
+use std::collections::HashMap;
 use std::fs;
-use std::path::Path;
+use std::path::{Path, PathBuf};
 
-const ENTRY_LIMIT: usize = 1000;
 // FIXME: The following limits should be reduced eventually.
-const ROOT_ENTRY_LIMIT: usize = 940;
-const ISSUES_ENTRY_LIMIT: usize = 1978;
+const ENTRY_LIMIT: usize = 885;
+const ROOT_ENTRY_LIMIT: usize = 891;
+const ISSUES_ENTRY_LIMIT: usize = 1977;
 
-fn check_entries(path: &Path, bad: &mut bool) {
-    for dir in Walk::new(&path.join("ui")) {
-        if let Ok(entry) = dir {
-            if entry.file_type().map(|ft| ft.is_dir()).unwrap_or(false) {
-                let dir_path = entry.path();
-                // Use special values for these dirs.
-                let is_root = path.join("ui") == dir_path;
-                let is_issues_dir = path.join("ui/issues") == dir_path;
-                let limit = if is_root {
-                    ROOT_ENTRY_LIMIT
-                } else if is_issues_dir {
-                    ISSUES_ENTRY_LIMIT
-                } else {
-                    ENTRY_LIMIT
-                };
+fn check_entries(tests_path: &Path, bad: &mut bool) {
+    let mut directories: HashMap<PathBuf, usize> = HashMap::new();
 
-                let count = WalkBuilder::new(&dir_path)
-                    .max_depth(Some(1))
-                    .build()
-                    .into_iter()
-                    .collect::<Vec<_>>()
-                    .len()
-                    - 1; // remove the dir itself
+    for dir in Walk::new(&tests_path.join("ui")) {
+        if let Ok(entry) = dir {
+            let parent = entry.path().parent().unwrap().to_path_buf();
+            *directories.entry(parent).or_default() += 1;
+        }
+    }
 
-                if count > limit {
-                    tidy_error!(
-                        bad,
-                        "following path contains more than {} entries, \
-                            you should move the test to some relevant subdirectory (current: {}): {}",
-                        limit,
-                        count,
-                        dir_path.display()
-                    );
-                }
-            }
+    let (mut max, mut max_root, mut max_issues) = (0usize, 0usize, 0usize);
+    for (dir_path, count) in directories {
+        // Use special values for these dirs.
+        let is_root = tests_path.join("ui") == dir_path;
+        let is_issues_dir = tests_path.join("ui/issues") == dir_path;
+        let (limit, maxcnt) = if is_root {
+            (ROOT_ENTRY_LIMIT, &mut max_root)
+        } else if is_issues_dir {
+            (ISSUES_ENTRY_LIMIT, &mut max_issues)
+        } else {
+            (ENTRY_LIMIT, &mut max)
+        };
+        *maxcnt = (*maxcnt).max(count);
+        if count > limit {
+            tidy_error!(
+                bad,
+                "following path contains more than {} entries, \
+                    you should move the test to some relevant subdirectory (current: {}): {}",
+                limit,
+                count,
+                dir_path.display()
+            );
         }
     }
+    if ENTRY_LIMIT > max {
+        tidy_error!(bad, "`ENTRY_LIMIT` is too high (is {ENTRY_LIMIT}, should be {max})");
+    }
+    if ROOT_ENTRY_LIMIT > max_root {
+        tidy_error!(
+            bad,
+            "`ROOT_ENTRY_LIMIT` is too high (is {ROOT_ENTRY_LIMIT}, should be {max_root})"
+        );
+    }
+    if ISSUES_ENTRY_LIMIT > max_issues {
+        tidy_error!(
+            bad,
+            "`ISSUES_ENTRY_LIMIT` is too high (is {ISSUES_ENTRY_LIMIT}, should be {max_issues})"
+        );
+    }
 }
 
 pub fn check(path: &Path, bad: &mut bool) {
     check_entries(&path, bad);
-    for path in &[&path.join("ui"), &path.join("ui-fulldeps")] {
-        crate::walk::walk_no_read(path, &mut |_| false, &mut |entry| {
-            let file_path = entry.path();
-            if let Some(ext) = file_path.extension() {
-                if ext == "stderr" || ext == "stdout" {
-                    // Test output filenames have one of the formats:
-                    // ```
-                    // $testname.stderr
-                    // $testname.$mode.stderr
-                    // $testname.$revision.stderr
-                    // $testname.$revision.$mode.stderr
-                    // ```
-                    //
-                    // For now, just make sure that there is a corresponding
-                    // `$testname.rs` file.
-                    //
-                    // NB: We do not use file_stem() as some file names have multiple `.`s and we
-                    // must strip all of them.
-                    let testname =
-                        file_path.file_name().unwrap().to_str().unwrap().split_once('.').unwrap().0;
-                    if !file_path.with_file_name(testname).with_extension("rs").exists() {
-                        tidy_error!(bad, "Stray file with UI testing output: {:?}", file_path);
-                    }
+    let (ui, ui_fulldeps) = (path.join("ui"), path.join("ui-fulldeps"));
+    let paths = [ui.as_path(), ui_fulldeps.as_path()];
+    crate::walk::walk_no_read(&paths, |_, _| false, &mut |entry| {
+        let file_path = entry.path();
+        if let Some(ext) = file_path.extension() {
+            if ext == "stderr" || ext == "stdout" {
+                // Test output filenames have one of the formats:
+                // ```
+                // $testname.stderr
+                // $testname.$mode.stderr
+                // $testname.$revision.stderr
+                // $testname.$revision.$mode.stderr
+                // ```
+                //
+                // For now, just make sure that there is a corresponding
+                // `$testname.rs` file.
+                //
+                // NB: We do not use file_stem() as some file names have multiple `.`s and we
+                // must strip all of them.
+                let testname =
+                    file_path.file_name().unwrap().to_str().unwrap().split_once('.').unwrap().0;
+                if !file_path.with_file_name(testname).with_extension("rs").exists() {
+                    tidy_error!(bad, "Stray file with UI testing output: {:?}", file_path);
+                }
 
-                    if let Ok(metadata) = fs::metadata(file_path) {
-                        if metadata.len() == 0 {
-                            tidy_error!(bad, "Empty file with UI testing output: {:?}", file_path);
-                        }
+                if let Ok(metadata) = fs::metadata(file_path) {
+                    if metadata.len() == 0 {
+                        tidy_error!(bad, "Empty file with UI testing output: {:?}", file_path);
                     }
                 }
             }
-        });
-    }
+        }
+    });
 }
diff --git a/src/tools/tidy/src/unit_tests.rs b/src/tools/tidy/src/unit_tests.rs
index 27f36c855..0a5dad887 100644
--- a/src/tools/tidy/src/unit_tests.rs
+++ b/src/tools/tidy/src/unit_tests.rs
@@ -11,18 +11,19 @@ use crate::walk::{filter_dirs, walk};
 use std::path::Path;
 
 pub fn check(root_path: &Path, bad: &mut bool) {
-    let core = &root_path.join("core");
-    let core_tests = &core.join("tests");
-    let core_benches = &core.join("benches");
-    let is_core = |path: &Path| {
-        path.starts_with(core) && !(path.starts_with(core_tests) || path.starts_with(core_benches))
+    let core = root_path.join("core");
+    let core_copy = core.clone();
+    let core_tests = core.join("tests");
+    let core_benches = core.join("benches");
+    let is_core = move |path: &Path| {
+        path.starts_with(&core)
+            && !(path.starts_with(&core_tests) || path.starts_with(&core_benches))
     };
 
-    let mut skip = |path: &Path| {
+    let skip = move |path: &Path, is_dir| {
         let file_name = path.file_name().unwrap_or_default();
-        if path.is_dir() {
+        if is_dir {
             filter_dirs(path)
-                || path.ends_with("tests")
                 || path.ends_with("src/doc")
                 || (file_name == "tests" || file_name == "benches") && !is_core(path)
         } else {
@@ -35,9 +36,9 @@ pub fn check(root_path: &Path, bad: &mut bool) {
         }
     };
 
-    walk(root_path, &mut skip, &mut |entry, contents| {
+    walk(root_path, skip, &mut |entry, contents| {
         let path = entry.path();
-        let is_core = path.starts_with(core);
+        let is_core = path.starts_with(&core_copy);
         for (i, line) in contents.lines().enumerate() {
             let line = line.trim();
             let is_test = || line.contains("#[test]") && !line.contains("`#[test]");
diff --git a/src/tools/tidy/src/walk.rs b/src/tools/tidy/src/walk.rs
index 4cfb70fa3..3539943eb 100644
--- a/src/tools/tidy/src/walk.rs
+++ b/src/tools/tidy/src/walk.rs
@@ -1,9 +1,8 @@
-use std::fs::File;
-use std::io::Read;
-use walkdir::{DirEntry, WalkDir};
+use ignore::DirEntry;
 
-use std::path::Path;
+use std::{ffi::OsStr, fs::File, io::Read, path::Path};
 
+/// The default directory filter.
 pub fn filter_dirs(path: &Path) -> bool {
     let skip = [
         "tidy-test-file",
@@ -30,40 +29,57 @@ pub fn filter_dirs(path: &Path) -> bool {
         // Filter RLS output directories
         "target/rls",
         "src/bootstrap/target",
+        "vendor",
     ];
     skip.iter().any(|p| path.ends_with(p))
 }
 
-pub fn walk_many(
-    paths: &[&Path],
-    skip: &mut dyn FnMut(&Path) -> bool,
+/// Filter for only files that end in `.rs`.
+pub fn filter_not_rust(path: &Path) -> bool {
+    path.extension() != Some(OsStr::new("rs")) && !path.is_dir()
+}
+
+pub fn walk(
+    path: &Path,
+    skip: impl Send + Sync + 'static + Fn(&Path, bool) -> bool,
     f: &mut dyn FnMut(&DirEntry, &str),
 ) {
-    for path in paths {
-        walk(path, skip, f);
-    }
+    walk_many(&[path], skip, f);
 }
 
-pub fn walk(path: &Path, skip: &mut dyn FnMut(&Path) -> bool, f: &mut dyn FnMut(&DirEntry, &str)) {
-    let mut contents = String::new();
-    walk_no_read(path, skip, &mut |entry| {
+pub fn walk_many(
+    paths: &[&Path],
+    skip: impl Send + Sync + 'static + Fn(&Path, bool) -> bool,
+    f: &mut dyn FnMut(&DirEntry, &str),
+) {
+    let mut contents = Vec::new();
+    walk_no_read(paths, skip, &mut |entry| {
         contents.clear();
-        if t!(File::open(entry.path()), entry.path()).read_to_string(&mut contents).is_err() {
-            contents.clear();
-        }
-        f(&entry, &contents);
+        let mut file = t!(File::open(entry.path()), entry.path());
+        t!(file.read_to_end(&mut contents), entry.path());
+        let contents_str = match std::str::from_utf8(&contents) {
+            Ok(s) => s,
+            Err(_) => return, // skip this file
+        };
+        f(&entry, &contents_str);
     });
 }
 
 pub(crate) fn walk_no_read(
-    path: &Path,
-    skip: &mut dyn FnMut(&Path) -> bool,
+    paths: &[&Path],
+    skip: impl Send + Sync + 'static + Fn(&Path, bool) -> bool,
     f: &mut dyn FnMut(&DirEntry),
 ) {
-    let walker = WalkDir::new(path).into_iter().filter_entry(|e| !skip(e.path()));
-    for entry in walker {
+    let mut walker = ignore::WalkBuilder::new(paths[0]);
+    for path in &paths[1..] {
+        walker.add(path);
+    }
+    let walker = walker.filter_entry(move |e| {
+        !skip(e.path(), e.file_type().map(|ft| ft.is_dir()).unwrap_or(false))
+    });
+    for entry in walker.build() {
         if let Ok(entry) = entry {
-            if entry.file_type().is_dir() {
+            if entry.file_type().map_or(true, |kind| kind.is_dir() || kind.is_symlink()) {
                 continue;
             }
             f(&entry);