Add IoSlice::as_bytes

library/std/src/io/mod.rs

@@ -1491,6 +1491,31 @@ impl<'a> IoSlice<'a> {
             bufs[0].advance(left);
         }
     }
+
+    /// Get the underlying bytes as a rust slice with the original lifetime
+    ///
+    /// # Example
+    ///
+    /// ```
+    /// #![feature(io_slice_as_bytes)]
+    /// use std::io::IoSlice;
+    ///
+    /// let data = b"abcdef";
+    ///
+    /// let mut io_slice = IoSlice::new(data);
+    /// let tail = &io_slice.into_bytes()[3..];
+    ///
+    /// // This works because `tail` doesn't borrow `io_slice`
+    /// io_slice = IoSlice::new(tail);
+    ///
+    /// assert_eq!(io_slice.into_bytes(), b"def");
+    /// ```
+    #[unstable(feature = "io_slice_as_bytes", issue = "111277")]
+    #[inline]
+    #[must_use]
+    pub const fn into_bytes(&self) -> &'a [u8] {
+        self.0.as_slice()
+    }
 }
 
 #[stable(feature = "iovec", since = "1.36.0")]

library/std/src/sys/pal/solid/io.rs

@@ -33,7 +33,7 @@ impl<'a> IoSlice<'a> {
     }
 
     #[inline]
-    pub fn as_slice(&self) -> &[u8] {
+    pub const fn as_slice(&self) -> &'a [u8] {
         unsafe { slice::from_raw_parts(self.vec.iov_base as *mut u8, self.vec.iov_len) }
     }
 }

library/std/src/sys/pal/unix/io.rs

@@ -33,7 +33,7 @@ impl<'a> IoSlice<'a> {
     }
 
     #[inline]
-    pub fn as_slice(&self) -> &[u8] {
+    pub const fn as_slice(&self) -> &'a [u8] {
         unsafe { slice::from_raw_parts(self.vec.iov_base as *mut u8, self.vec.iov_len) }
     }
 }

library/std/src/sys/pal/unsupported/io.rs

@@ -15,7 +15,7 @@ impl<'a> IoSlice<'a> {
     }
 
     #[inline]
-    pub fn as_slice(&self) -> &[u8] {
+    pub const fn as_slice(&self) -> &'a [u8] {
         self.0
     }
 }

library/std/src/sys/pal/wasi/io.rs

@@ -30,7 +30,7 @@ impl<'a> IoSlice<'a> {
     }
 
     #[inline]
-    pub fn as_slice(&self) -> &[u8] {
+    pub const fn as_slice(&self) -> &'a [u8] {
         unsafe { slice::from_raw_parts(self.vec.buf as *const u8, self.vec.buf_len) }
     }
 }

library/std/src/sys/pal/windows/io.rs

@@ -35,7 +35,7 @@ impl<'a> IoSlice<'a> {
     }
 
     #[inline]
-    pub fn as_slice(&self) -> &[u8] {
+    pub const fn as_slice(&self) -> &'a [u8] {
         unsafe { slice::from_raw_parts(self.vec.buf, self.vec.len as usize) }
     }
 }