1 files changed, 22 insertions, 20 deletions

diff --git a/compiler/rustc_incremental/src/persist/fs.rs b/compiler/rustc_incremental/src/persist/fs.rs
index 7708deece..db8ea2bfe 100644
--- a/compiler/rustc_incremental/src/persist/fs.rs
+++ b/compiler/rustc_incremental/src/persist/fs.rs
@@ -427,13 +427,11 @@ fn copy_files(sess: &Session, target_dir: &Path, source_dir: &Path) -> Result<bo
     if sess.opts.unstable_opts.incremental_info {
         eprintln!(
             "[incremental] session directory: \
-                  {} files hard-linked",
-            files_linked
+                  {files_linked} files hard-linked"
         );
         eprintln!(
             "[incremental] session directory: \
-                 {} files copied",
-            files_copied
+                 {files_copied} files copied"
         );
     }
 
@@ -540,9 +538,13 @@ where
             continue;
         }
 
-        let timestamp = extract_timestamp_from_session_dir(&directory_name).unwrap_or_else(|_| {
-            bug!("unexpected incr-comp session dir: {}", session_dir.display())
-        });
+        let timestamp = match extract_timestamp_from_session_dir(&directory_name) {
+            Ok(timestamp) => timestamp,
+            Err(e) => {
+                debug!("unexpected incr-comp session dir: {}: {}", session_dir.display(), e);
+                continue;
+            }
+        };
 
         if timestamp > best_candidate.0 {
             best_candidate = (timestamp, Some(session_dir.clone()));
@@ -564,14 +566,14 @@ fn is_session_directory_lock_file(file_name: &str) -> bool {
     file_name.starts_with("s-") && file_name.ends_with(LOCK_FILE_EXT)
 }
 
-fn extract_timestamp_from_session_dir(directory_name: &str) -> Result<SystemTime, ()> {
+fn extract_timestamp_from_session_dir(directory_name: &str) -> Result<SystemTime, &'static str> {
     if !is_session_directory(directory_name) {
-        return Err(());
+        return Err("not a directory");
     }
 
     let dash_indices: Vec<_> = directory_name.match_indices('-').map(|(idx, _)| idx).collect();
     if dash_indices.len() != 3 {
-        return Err(());
+        return Err("not three dashes in name");
     }
 
     string_to_timestamp(&directory_name[dash_indices[0] + 1..dash_indices[1]])
@@ -583,11 +585,11 @@ fn timestamp_to_string(timestamp: SystemTime) -> String {
     base_n::encode(micros as u128, INT_ENCODE_BASE)
 }
 
-fn string_to_timestamp(s: &str) -> Result<SystemTime, ()> {
+fn string_to_timestamp(s: &str) -> Result<SystemTime, &'static str> {
     let micros_since_unix_epoch = u64::from_str_radix(s, INT_ENCODE_BASE as u32);
 
     if micros_since_unix_epoch.is_err() {
-        return Err(());
+        return Err("timestamp not an int");
     }
 
     let micros_since_unix_epoch = micros_since_unix_epoch.unwrap();
@@ -604,7 +606,7 @@ fn crate_path(sess: &Session, crate_name: Symbol, stable_crate_id: StableCrateId
 
     let stable_crate_id = base_n::encode(stable_crate_id.as_u64() as u128, INT_ENCODE_BASE);
 
-    let crate_name = format!("{}-{}", crate_name, stable_crate_id);
+    let crate_name = format!("{crate_name}-{stable_crate_id}");
     incr_dir.join(crate_name)
 }
 
@@ -730,13 +732,13 @@ pub fn garbage_collect_session_directories(sess: &Session) -> io::Result<()> {
             debug!("garbage_collect_session_directories() - inspecting: {}", directory_name);
 
             let Ok(timestamp) = extract_timestamp_from_session_dir(directory_name) else {
-            debug!(
-                "found session-dir with malformed timestamp: {}",
-                crate_directory.join(directory_name).display()
-            );
-            // Ignore it
-            return None;
-        };
+                debug!(
+                    "found session-dir with malformed timestamp: {}",
+                    crate_directory.join(directory_name).display()
+                );
+                // Ignore it
+                return None;
+            };
 
             if is_finalized(directory_name) {
                 let lock_file_path = crate_directory.join(lock_file_name);