Fix lintcheck --fix

There were several issues:
- `--fix` was ignored as part of rust-lang#9461
-  `--filter` in conjunction to `--fix` was broken due to rust-lang#9703

After `lintcheck --fix` is used, crates will be re-extracted since their content has been modified

Author: kraktus

lintcheck/src/main.rs

@@ -182,33 +182,35 @@ impl CrateSource {
             CrateSource::CratesIo { name, version, options } => {
                 let extract_dir = PathBuf::from(LINTCHECK_SOURCES);
                 let krate_download_dir = PathBuf::from(LINTCHECK_DOWNLOADS);
+                let extracted_krate_dir = extract_dir.join(format!("{name}-{version}/"));
 
                 // url to download the crate from crates.io
                 let url = format!("https://crates.io/api/v1/crates/{name}/{version}/download");
                 println!("Downloading and extracting {name} {version} from {url}");
                 create_dirs(&krate_download_dir, &extract_dir);
 
                 let krate_file_path = krate_download_dir.join(format!("{name}-{version}.crate.tar.gz"));
-                // don't download/extract if we already have done so
+                // don't download if we already have done so
                 if !krate_file_path.is_file() {
                     // create a file path to download and write the crate data into
                     let mut krate_dest = std::fs::File::create(&krate_file_path).unwrap();
                     let mut krate_req = get(&url).unwrap().into_reader();
                     // copy the crate into the file
                     std::io::copy(&mut krate_req, &mut krate_dest).unwrap();
+                }
 
-                    // unzip the tarball
-                    let ungz_tar = flate2::read::GzDecoder::new(std::fs::File::open(&krate_file_path).unwrap());
-                    // extract the tar archive
-                    let mut archive = tar::Archive::new(ungz_tar);
-                    archive.unpack(&extract_dir).expect("Failed to extract!");
+                // if the source code was altered (previous use of `--fix`), we need to restore the crate
+                // to its original state by re-extracting it
+                if !extracted_krate_dir.exists() || has_been_modified(&extracted_krate_dir) {
+                    debug!("extracting {} {}", name, version);
+                    Self::extract(&extract_dir, &krate_file_path);
                 }
                 // crate is extracted, return a new Krate object which contains the path to the extracted
                 // sources that clippy can check
                 Crate {
                     version: version.clone(),
                     name: name.clone(),
-                    path: extract_dir.join(format!("{name}-{version}/")),
+                    path: extracted_krate_dir,
                     options: options.clone(),
                 }
             },
@@ -299,6 +301,14 @@ impl CrateSource {
             },
         }
     }
+
+    fn extract(extract_dir: &Path, krate_file_path: &Path) {
+        // unzip the tarball
+        let ungz_tar = flate2::read::GzDecoder::new(std::fs::File::open(krate_file_path).unwrap());
+        // extract the tar archive
+        let mut archive = tar::Archive::new(ungz_tar);
+        archive.unpack(extract_dir).expect("Failed to extract!");
+    }
 }
 
 impl Crate {
@@ -338,7 +348,9 @@ impl Crate {
         let shared_target_dir = clippy_project_root().join("target/lintcheck/shared_target_dir");
 
         let mut cargo_clippy_args = if config.fix {
-            vec!["--fix", "--"]
+            // need to pass `clippy` arg even if already feeding `cargo-clippy`
+            // see https://github.com/rust-lang/rust-clippy/pull/9461
+            vec!["clippy", "--fix", "--allow-no-vcs", "--"]
         } else {
             vec!["--", "--message-format=json", "--"]
         };
@@ -348,16 +360,19 @@ impl Crate {
             for opt in options {
                 clippy_args.push(opt);
             }
-        } else {
-            clippy_args.extend(["-Wclippy::pedantic", "-Wclippy::cargo"]);
         }
 
-        if lint_filter.is_empty() {
-            clippy_args.push("--cap-lints=warn");
+        // cap-lints flag is ignored when using `clippy --fix` for now
+        // So it needs to be passed directly to rustc
+        // see https://github.com/rust-lang/rust-clippy/issues/9703
+        let rustc_flags = if lint_filter.is_empty() {
+            clippy_args.extend(["-Wclippy::pedantic", "-Wclippy::cargo"]);
+            "--cap-lints=warn".to_string()
         } else {
-            clippy_args.push("--cap-lints=allow");
-            clippy_args.extend(lint_filter.iter().map(std::string::String::as_str));
-        }
+            let mut lint_filter_buf = lint_filter.clone();
+            lint_filter_buf.push("--cap-lints=allow".to_string());
+            lint_filter_buf.join(" ")
+        };
 
         if let Some(server) = server {
             let target = shared_target_dir.join("recursive");
@@ -396,6 +411,7 @@ impl Crate {
         let all_output = Command::new(&cargo_clippy_path)
             // use the looping index to create individual target dirs
             .env("CARGO_TARGET_DIR", shared_target_dir.join(format!("_{thread_index:?}")))
+            .env("RUSTFLAGS", rustc_flags)
             .args(&cargo_clippy_args)
             .current_dir(&self.path)
             .output()
@@ -807,6 +823,14 @@ fn clippy_project_root() -> &'static Path {
     Path::new(env!("CARGO_MANIFEST_DIR")).parent().unwrap()
 }
 
+fn has_been_modified(extracted_krate_dir: &Path) -> bool {
+    extracted_krate_dir.metadata().map_or(false, |metadata| {
+        metadata.created().map_or(false, |created| {
+            metadata.modified().map_or(false, |modified| created != modified)
+        })
+    })
+}
+
 #[test]
 fn lintcheck_test() {
     let args = [