ffi::c_str smaller as_bytes

Author: klensy

library/std/src/ffi/c_str.rs

@@ -613,7 +613,8 @@ impl CString {
     #[inline]
     #[stable(feature = "rust1", since = "1.0.0")]
     pub fn as_bytes(&self) -> &[u8] {
-        &self.inner[..self.inner.len() - 1]
+        // SAFETY: CString has a length at least 1
+        unsafe { self.inner.get_unchecked(..self.inner.len() - 1) }
     }
 
     /// Equivalent to [`CString::as_bytes()`] except that the
@@ -1322,7 +1323,8 @@ impl CStr {
     #[stable(feature = "rust1", since = "1.0.0")]
     pub fn to_bytes(&self) -> &[u8] {
         let bytes = self.to_bytes_with_nul();
-        &bytes[..bytes.len() - 1]
+        // SAFETY: to_bytes_with_nul returns slice with length at least 1
+        unsafe { bytes.get_unchecked(..bytes.len() - 1) }
     }
 
     /// Converts this C string to a byte slice containing the trailing 0 byte.