Make ByteStr/ByteString a more-opaque wrapper like OsStr/OsString

Author: clarfonthey

library/alloc/src/bstr.rs

@@ -10,6 +10,7 @@
 #![stable(feature = "rust1", since = "1.0.0")]
 
 use core::borrow::{Borrow, BorrowMut};
+use core::bstr::ByteStr;
 #[cfg(not(no_global_oom_handling))]
 use core::clone::TrivialClone;
 #[cfg(not(no_global_oom_handling))]
@@ -661,6 +662,16 @@ impl [u8] {
         me.make_ascii_lowercase();
         me
     }
+
+    /// Converts a `Box<[u8]>` into a `Box<ByteStr>` without copying or allocating.
+    #[cfg(not(no_global_oom_handling))]
+    #[rustc_allow_incoherent_impl]
+    #[unstable(feature = "bstr", issue = "134915")]
+    #[inline]
+    pub fn into_boxed_byte_str(self: Box<[u8]>) -> Box<ByteStr> {
+        // SAFETY: `ByteStr` is a thin wrapper over `[u8]`
+        unsafe { Box::from_raw(Box::into_raw(self) as _) }
+    }
 }
 
 ////////////////////////////////////////////////////////////////////////////////

library/alloc/src/slice.rs

@@ -93,6 +93,8 @@ pub use self::extract_if::ExtractIf;
 use crate::alloc::{Allocator, Global};
 use crate::borrow::{Cow, ToOwned};
 use crate::boxed::Box;
+#[cfg(not(no_global_oom_handling))]
+use crate::bstr::ByteString;
 use crate::collections::TryReserveError;
 use crate::raw_vec::RawVec;
 
@@ -3350,6 +3352,17 @@ impl<T: Clone, A: Allocator> Vec<T, A> {
     }
 }
 
+#[cfg(not(no_global_oom_handling))]
+impl Vec<u8> {
+    /// Converts a vector of bytes into a byte string.
+    #[unstable(feature = "bstr", issue = "134915")]
+    #[inline]
+    #[rustc_const_unstable(feature = "bstr", issue = "134915")]
+    pub const fn into_byte_string(self) -> ByteString {
+        ByteString(self)
+    }
+}
+
 impl<T, A: Allocator, const N: usize> Vec<[T; N], A> {
     /// Takes a `Vec<[T; N]>` and flattens it into a `Vec<T>`.
     ///