Move WTF-8 code from std to core/alloc

4 files changed, 40 insertions, 8 deletions

diff --git a/library/std/src/lib.rs b/library/std/src/lib.rs
index ab417b6c72f..ca76dcc5147 100644
--- a/library/std/src/lib.rs
+++ b/library/std/src/lib.rs
@@ -391,6 +391,7 @@
 #![feature(try_with_capacity)]
 #![feature(unique_rc_arc)]
 #![feature(vec_into_raw_parts)]
+#![feature(wtf8_internals)]
 // tidy-alphabetical-end
 //
 // Library features (unwind):
diff --git a/library/std/src/os/windows/ffi.rs b/library/std/src/os/windows/ffi.rs
index 496443dbbc3..345d5b74285 100644
--- a/library/std/src/os/windows/ffi.rs
+++ b/library/std/src/os/windows/ffi.rs
@@ -53,12 +53,13 @@
 
 #![stable(feature = "rust1", since = "1.0.0")]
 
+use alloc::wtf8::Wtf8Buf;
+
 use crate::ffi::{OsStr, OsString};
+use crate::fmt;
+use crate::iter::FusedIterator;
 use crate::sealed::Sealed;
 use crate::sys::os_str::Buf;
-#[stable(feature = "rust1", since = "1.0.0")]
-pub use crate::sys_common::wtf8::EncodeWide;
-use crate::sys_common::wtf8::Wtf8Buf;
 use crate::sys_common::{AsInner, FromInner};
 
 /// Windows-specific extensions to [`OsString`].
@@ -130,6 +131,35 @@ pub trait OsStrExt: Sealed {
 impl OsStrExt for OsStr {
     #[inline]
     fn encode_wide(&self) -> EncodeWide<'_> {
-        self.as_inner().inner.encode_wide()
+        EncodeWide { inner: self.as_inner().inner.encode_wide() }
+    }
+}
+
+/// Iterator returned by [`OsStrExt::encode_wide`].
+#[stable(feature = "rust1", since = "1.0.0")]
+#[derive(Clone)]
+pub struct EncodeWide<'a> {
+    inner: alloc::wtf8::EncodeWide<'a>,
+}
+#[stable(feature = "encode_wide_debug", since = "CURRENT_RUSTC_VERSION")]
+impl fmt::Debug for EncodeWide<'_> {
+    fn fmt(&self, f: &mut fmt::Formatter<'_>) -> fmt::Result {
+        fmt::Debug::fmt(&self.inner, f)
+    }
+}
+#[stable(feature = "rust1", since = "1.0.0")]
+impl Iterator for EncodeWide<'_> {
+    type Item = u16;
+
+    #[inline]
+    fn next(&mut self) -> Option<u16> {
+        self.inner.next()
+    }
+
+    #[inline]
+    fn size_hint(&self) -> (usize, Option<usize>) {
+        self.inner.size_hint()
     }
 }
+#[stable(feature = "encode_wide_fused_iterator", since = "1.62.0")]
+impl FusedIterator for EncodeWide<'_> {}
diff --git a/library/std/src/sys/os_str/wtf8.rs b/library/std/src/sys/os_str/wtf8.rs
index bbc704ebf86..96da891874e 100644
--- a/library/std/src/sys/os_str/wtf8.rs
+++ b/library/std/src/sys/os_str/wtf8.rs
@@ -1,12 +1,12 @@
 //! The underlying OsString/OsStr implementation on Windows is a
 //! wrapper around the "WTF-8" encoding; see the `wtf8` module for more.
+use alloc::wtf8::{Wtf8, Wtf8Buf};
 use core::clone::CloneToUninit;
 
 use crate::borrow::Cow;
 use crate::collections::TryReserveError;
 use crate::rc::Rc;
 use crate::sync::Arc;
-use crate::sys_common::wtf8::{Wtf8, Wtf8Buf, check_utf8_boundary};
 use crate::sys_common::{AsInner, FromInner, IntoInner};
 use crate::{fmt, mem};
 
@@ -220,7 +220,9 @@ impl Buf {
     /// trailing surrogate half.
     #[inline]
     pub unsafe fn extend_from_slice_unchecked(&mut self, other: &[u8]) {
-        self.inner.extend_from_slice(other);
+        unsafe {
+            self.inner.extend_from_slice_unchecked(other);
+        }
     }
 }
 
@@ -238,7 +240,7 @@ impl Slice {
     #[track_caller]
     #[inline]
     pub fn check_public_boundary(&self, index: usize) {
-        check_utf8_boundary(&self.inner, index);
+        self.inner.check_utf8_boundary(index);
     }
 
     #[inline]
diff --git a/library/std/src/sys_common/mod.rs b/library/std/src/sys_common/mod.rs
index 24b6cff1309..ec45c723e0d 100644
--- a/library/std/src/sys_common/mod.rs
+++ b/library/std/src/sys_common/mod.rs
@@ -21,7 +21,6 @@
 mod tests;
 
 pub mod wstr;
-pub mod wtf8;
 
 // common error constructors