Track `clippy.toml` and `Cargo.toml` in `file_depinfo`

Causes cargo to re-run clippy when those paths are modified

Also tracks the path to `clippy-driver` in debug mode to remove the
workarounds in `cargo dev lint` and `lintcheck`

clippy_dev/Cargo.toml

@@ -10,7 +10,6 @@ indoc = "1.0"
 itertools = "0.10.1"
 opener = "0.5"
 shell-escape = "0.1"
-tempfile = "3.2"
 walkdir = "2.3"
 
 [features]

clippy_dev/src/lint.rs

@@ -36,20 +36,12 @@ pub fn run<'a>(path: &str, args: impl Iterator<Item = &'a String>) {
     } else {
         exit_if_err(Command::new("cargo").arg("build").status());
 
-        // Run in a tempdir as changes to clippy do not retrigger linting
-        let target = tempfile::Builder::new()
-            .prefix("clippy")
-            .tempdir()
-            .expect("failed to create tempdir");
-
         let status = Command::new(cargo_clippy_path())
             .arg("clippy")
             .args(args)
             .current_dir(path)
-            .env("CARGO_TARGET_DIR", target.as_ref())
             .status();
 
-        target.close().expect("failed to remove tempdir");
         exit_if_err(status);
     }
 }

clippy_lints/src/lib.rs

@@ -49,6 +49,9 @@ extern crate clippy_utils;
 #[macro_use]
 extern crate declare_clippy_lint;
 
+use std::io;
+use std::path::PathBuf;
+
 use clippy_utils::parse_msrv;
 use rustc_data_structures::fx::FxHashSet;
 use rustc_lint::{Lint, LintId};
@@ -303,8 +306,8 @@ mod zero_div_zero;
 mod zero_sized_map_values;
 // end lints modules, do not remove this comment, it’s used in `update_lints`
 
-pub use crate::utils::conf::Conf;
 use crate::utils::conf::{format_error, TryConf};
+pub use crate::utils::conf::{lookup_conf_file, Conf};
 
 /// Register all pre expansion lints
 ///
@@ -361,8 +364,8 @@ fn read_msrv(conf: &Conf, sess: &Session) -> Option<RustcVersion> {
 }
 
 #[doc(hidden)]
-pub fn read_conf(sess: &Session) -> Conf {
-    let file_name = match utils::conf::lookup_conf_file() {
+pub fn read_conf(sess: &Session, path: &io::Result<Option<PathBuf>>) -> Conf {
+    let file_name = match path {
         Ok(Some(path)) => path,
         Ok(None) => return Conf::default(),
         Err(error) => {
@@ -372,7 +375,7 @@ pub fn read_conf(sess: &Session) -> Conf {
         },
     };
 
-    let TryConf { conf, errors, warnings } = utils::conf::read(&file_name);
+    let TryConf { conf, errors, warnings } = utils::conf::read(file_name);
     // all conf errors are non-fatal, we just use the default conf in case of error
     for error in errors {
         sess.err(format!(

clippy_lints/src/utils/conf.rs

@@ -390,6 +390,10 @@ define_Conf! {
 }
 
 /// Search for the configuration file.
+///
+/// # Errors
+///
+/// Returns any unexpected filesystem error encountered when searching for the config file
 pub fn lookup_conf_file() -> io::Result<Option<PathBuf>> {
     /// Possible filename to search for.
     const CONFIG_FILE_NAMES: [&str; 2] = [".clippy.toml", "clippy.toml"];

lintcheck/src/main.rs

@@ -544,34 +544,6 @@ fn gather_stats(clippy_warnings: &[ClippyWarning]) -> (String, HashMap<&String,
     (stats_string, counter)
 }
 
-/// check if the latest modification of the logfile is older than the modification date of the
-/// clippy binary, if this is true, we should clean the lintchec shared target directory and recheck
-fn lintcheck_needs_rerun(lintcheck_logs_path: &Path, paths: [&Path; 2]) -> bool {
-    if !lintcheck_logs_path.exists() {
-        return true;
-    }
-
-    let clippy_modified: std::time::SystemTime = {
-        let [cargo, driver] = paths.map(|p| {
-            std::fs::metadata(p)
-                .expect("failed to get metadata of file")
-                .modified()
-                .expect("failed to get modification date")
-        });
-        // the oldest modification of either of the binaries
-        std::cmp::max(cargo, driver)
-    };
-
-    let logs_modified: std::time::SystemTime = std::fs::metadata(lintcheck_logs_path)
-        .expect("failed to get metadata of file")
-        .modified()
-        .expect("failed to get modification date");
-
-    // time is represented in seconds since X
-    // logs_modified 2 and clippy_modified 5 means clippy binary is older and we need to recheck
-    logs_modified < clippy_modified
-}
-
 #[allow(clippy::too_many_lines)]
 fn main() {
     // We're being executed as a `RUSTC_WRAPPER` as part of `--recursive`
@@ -594,23 +566,6 @@ fn main() {
     let cargo_clippy_path = fs::canonicalize(format!("target/debug/cargo-clippy{EXE_SUFFIX}")).unwrap();
     let clippy_driver_path = fs::canonicalize(format!("target/debug/clippy-driver{EXE_SUFFIX}")).unwrap();
 
-    // if the clippy bin is newer than our logs, throw away target dirs to force clippy to
-    // refresh the logs
-    if lintcheck_needs_rerun(
-        &config.lintcheck_results_path,
-        [&cargo_clippy_path, &clippy_driver_path],
-    ) {
-        let shared_target_dir = "target/lintcheck/shared_target_dir";
-        // if we get an Err here, the shared target dir probably does simply not exist
-        if let Ok(metadata) = std::fs::metadata(shared_target_dir) {
-            if metadata.is_dir() {
-                println!("Clippy is newer than lint check logs, clearing lintcheck shared target dir...");
-                std::fs::remove_dir_all(shared_target_dir)
-                    .expect("failed to remove target/lintcheck/shared_target_dir");
-            }
-        }
-    }
-
     // assert that clippy is found
     assert!(
         cargo_clippy_path.is_file(),

src/driver.rs

@@ -1,4 +1,5 @@
 #![feature(rustc_private)]
+#![feature(let_chains)]
 #![feature(once_cell)]
 #![cfg_attr(feature = "deny-warnings", deny(warnings))]
 // warn on lints, that are included in `rust-lang/rust`s bootstrap
@@ -71,6 +72,32 @@ fn track_clippy_args(parse_sess: &mut ParseSess, args_env_var: &Option<String>)
     ));
 }
 
+/// Track files that may be accessed at runtime in `file_depinfo` so that cargo will re-run clippy
+/// when any of them are modified
+fn track_files(parse_sess: &mut ParseSess, conf_path_string: Option<String>) {
+    let file_depinfo = parse_sess.file_depinfo.get_mut();
+
+    // Used by `clippy::cargo` lints and to determine the MSRV. `cargo clippy` executes `clippy-driver`
+    // with the current directory set to `CARGO_MANIFEST_DIR` so a relative path is fine
+    if Path::new("Cargo.toml").exists() {
+        file_depinfo.insert(Symbol::intern("Cargo.toml"));
+    }
+
+    // `clippy.toml`
+    if let Some(path) = conf_path_string {
+        file_depinfo.insert(Symbol::intern(&path));
+    }
+
+    // During development track the `clippy-driver` executable so that cargo will re-run clippy whenever
+    // it is rebuilt
+    if cfg!(debug_assertions)
+        && let Ok(current_exe) = env::current_exe()
+        && let Some(current_exe) = current_exe.to_str()
+    {
+        file_depinfo.insert(Symbol::intern(current_exe));
+    }
+}
+
 struct DefaultCallbacks;
 impl rustc_driver::Callbacks for DefaultCallbacks {}
 
@@ -97,10 +124,18 @@ impl rustc_driver::Callbacks for ClippyCallbacks {
     // JUSTIFICATION: necessary in clippy driver to set `mir_opt_level`
     #[allow(rustc::bad_opt_access)]
     fn config(&mut self, config: &mut interface::Config) {
+        let conf_path = clippy_lints::lookup_conf_file();
+        let conf_path_string = if let Ok(Some(path)) = &conf_path {
+            path.to_str().map(String::from)
+        } else {
+            None
+        };
+
         let previous = config.register_lints.take();
         let clippy_args_var = self.clippy_args_var.take();
         config.parse_sess_created = Some(Box::new(move |parse_sess| {
             track_clippy_args(parse_sess, &clippy_args_var);
+            track_files(parse_sess, conf_path_string);
         }));
         config.register_lints = Some(Box::new(move |sess, lint_store| {
             // technically we're ~guaranteed that this is none but might as well call anything that
@@ -109,7 +144,7 @@ impl rustc_driver::Callbacks for ClippyCallbacks {
                 (previous)(sess, lint_store);
             }
 
-            let conf = clippy_lints::read_conf(sess);
+            let conf = clippy_lints::read_conf(sess, &conf_path);
             clippy_lints::register_plugins(lint_store, sess, &conf);
             clippy_lints::register_pre_expansion_lints(lint_store, sess, &conf);
             clippy_lints::register_renamed(lint_store);