Normalize path separator before filtering

src/cli/run.rs

@@ -16,6 +16,7 @@ use unicode_width::UnicodeWidthStr;
 
 use crate::cli::ExitStatus;
 use crate::config::Stage;
+use crate::fs::normalize_path;
 use crate::git::{get_all_files, get_changed_files, get_diff, get_staged_files};
 use crate::hook::{Hook, Project};
 use crate::identify::tags_from_path;
@@ -97,7 +98,7 @@ pub(crate) async fn run(
 
     let filenames = all_filenames(hook_stage, from_ref, to_ref, all_files, files).await?;
     let filenames = filter_filenames(
-        filenames.par_iter(),
+        filenames.par_iter().map(normalize_path),
         project.config().files.as_deref(),
         project.config().exclude.as_deref(),
     )?

src/fs.rs

@@ -20,6 +20,7 @@
 // OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN THE
 // SOFTWARE.
 
+use std::borrow::Cow;
 use std::fmt::Display;
 use std::path::{Path, PathBuf};
 use std::sync::LazyLock;
@@ -181,3 +182,26 @@ pub fn copy_dir_all(src: impl AsRef<Path>, dst: impl AsRef<Path>) -> std::io::Re
     }
     Ok(())
 }
+
+/// Normalizes a path to use `/` as a separator everywhere, even on platforms
+/// that recognize other characters as separators.
+#[cfg(unix)]
+pub(crate) fn normalize_path(path: Cow<'_, [u8]>) -> Cow<'_, [u8]> {
+    // UNIX only uses /, so we're good.
+    path
+}
+
+/// Normalizes a path to use `/` as a separator everywhere, even on platforms
+/// that recognize other characters as separators.
+#[cfg(not(unix))]
+pub(crate) fn normalize_path(mut path: Cow<[u8]>) -> Cow<[u8]> {
+    use std::path::is_separator;
+
+    for i in 0..path.len() {
+        if path[i] == b'/' || !is_separator(char::from(path[i])) {
+            continue;
+        }
+        path.to_mut()[i] = b'/';
+    }
+    path
+}