1 files changed, 16 insertions, 0 deletions
diff --git a/third_party/rust/clap/src/strext.rs b/third_party/rust/clap/src/strext.rs
new file mode 100644
index 0000000000..6f81367ab2
--- /dev/null
+++ b/third_party/rust/clap/src/strext.rs
@@ -0,0 +1,16 @@
+pub trait _StrExt {
+    fn _is_char_boundary(&self, index: usize) -> bool;
+}
+
+impl _StrExt for str {
+    #[inline]
+    fn _is_char_boundary(&self, index: usize) -> bool {
+        if index == self.len() {
+            return true;
+        }
+        match self.as_bytes().get(index) {
+            None => false,
+            Some(&b) => b < 128 || b >= 192,
+        }
+    }
+}