Match file regexes against path bytes

crates/prek/src/cli/run/filter.rs

@@ -764,15 +764,23 @@ mod tests {
 
     #[cfg(unix)]
     #[test]
-    fn filename_filter_skips_non_utf8_paths_with_regex_include() {
+    fn filename_filter_matches_non_utf8_paths_with_regex_include() {
         use std::ffi::OsStr;
         use std::os::unix::ffi::OsStrExt as _;
 
         let include = regex_pattern(r".*\.py$");
         let path = Path::new(OsStr::from_bytes(b"bad-\xff.py"));
         let filter = FilenameFilter::new(Some(&include), None);
 
-        assert!(!filter.matches(path));
+        assert!(filter.matches(path));
+    }
+
+    #[test]
+    fn filename_filter_regex_keeps_unicode_character_classes() {
+        let include = regex_pattern(r"^\w+\.py$");
+        let filter = FilenameFilter::new(Some(&include), None);
+
+        assert!(filter.matches(Path::new("café.py")));
     }
 
     #[test]

crates/prek/src/config.rs

@@ -4,7 +4,7 @@ use std::fmt::Display;
 use std::path::Path;
 
 use anyhow::Result;
-use fancy_regex::Regex;
+use fancy_regex::{BytesMode, Regex, RegexBuilder};
 use globset::{Glob, GlobSet};
 use itertools::Itertools;
 use owo_colors::OwoColorize;
@@ -327,16 +327,18 @@ impl FilePattern {
     }
 
     pub(crate) fn regex(pattern: &str) -> Result<Self, fancy_regex::Error> {
-        Ok(Self::Regex(Regex::new(pattern)?))
+        let regex = RegexBuilder::new(pattern)
+            .bytes_mode(BytesMode::UnicodeBytes)
+            .build()?;
+        Ok(Self::Regex(regex))
     }
 
     pub(crate) fn is_match(&self, path: &Path) -> bool {
         match self {
             FilePattern::Never => false,
-            // Regex patterns are text matchers; globs can match OS paths directly.
-            FilePattern::Regex(regex) => path
-                .to_str()
-                .is_some_and(|path| regex.is_match(path).unwrap_or(false)),
+            FilePattern::Regex(regex) => regex
+                .is_match(path.as_os_str().as_encoded_bytes())
+                .unwrap_or(false),
             FilePattern::Glob(globs) => globs.is_match(path),
         }
     }
@@ -360,9 +362,9 @@ impl TryFrom<FilePatternWire> for FilePattern {
 
     fn try_from(value: FilePatternWire) -> Result<Self, Self::Error> {
         match value {
-            FilePatternWire::Glob { glob } => Ok(Self::Glob(GlobPatterns::new(vec![glob])?)),
-            FilePatternWire::GlobList { glob } => Ok(Self::Glob(GlobPatterns::new(glob)?)),
-            FilePatternWire::Regex(pattern) => Ok(Self::Regex(Regex::new(&pattern)?)),
+            FilePatternWire::Glob { glob } => Ok(Self::glob(vec![glob])?),
+            FilePatternWire::GlobList { glob } => Ok(Self::glob(glob)?),
+            FilePatternWire::Regex(pattern) => Ok(Self::regex(&pattern)?),
         }
     }
 }

crates/prek/src/hooks/pre_commit_hooks/no_commit_to_branch.rs

@@ -32,7 +32,7 @@ impl Args {
 
         for pattern in &self.patterns {
             let pattern = Regex::new(pattern).context("Failed to compile regex patterns")?;
-            if pattern.is_match(branch).unwrap_or(false) {
+            if pattern.is_match(branch)? {
                 return Ok(true);
             }
         }
@@ -67,3 +67,19 @@ pub(crate) async fn run(hook: &Hook) -> Result<HookOutput> {
         Ok(HookOutput::unchanged(0, Vec::new()))
     }
 }
+
+#[cfg(test)]
+mod tests {
+    use super::Args;
+
+    #[test]
+    fn pattern_runtime_errors_are_reported() {
+        let args = Args {
+            branches: Vec::new(),
+            patterns: vec![r"^(a|aa)+\1$".to_string()],
+        };
+        let branch = format!("{}b", "a".repeat(40));
+
+        assert!(args.check_protected(&branch).is_err());
+    }
+}