Remove from_vec_offset

src/bytes.rs

@@ -1066,7 +1066,9 @@ unsafe fn promotable_to_mut(
         let cap = off + len;
         let v = Vec::from_raw_parts(buf, cap, cap);
 
-        BytesMut::from_vec_offset(v, off)
+        let mut b = BytesMut::from_vec(v);
+        b.advance_unchecked(off);
+        b
     }
 }
 
@@ -1242,10 +1244,11 @@ unsafe fn shared_to_mut_impl(shared: *mut Shared, ptr: *const u8, len: usize) ->
 
         // Rebuild Vec
         let off = offset_from(ptr, buf);
-        let len = len + off;
-        let v = Vec::from_raw_parts(buf, len, cap);
+        let v = Vec::from_raw_parts(buf, len + off, cap);
 
-        BytesMut::from_vec_offset(v, off)
+        let mut b = BytesMut::from_vec(v);
+        b.advance_unchecked(off);
+        b
     } else {
         // Copy the data from Shared in a new Vec, then release it
         let v = slice::from_raw_parts(ptr, len).to_vec();

src/bytes_mut.rs

@@ -829,20 +829,13 @@ impl BytesMut {
     // suddenly a lot more expensive.
     #[inline]
     pub(crate) fn from_vec(vec: Vec<u8>) -> BytesMut {
-        unsafe { BytesMut::from_vec_offset(vec, 0) }
-    }
-
-    #[inline]
-    pub(crate) unsafe fn from_vec_offset(vec: Vec<u8>, off: usize) -> BytesMut {
         let mut vec = ManuallyDrop::new(vec);
-        let ptr = vptr(vec.as_mut_ptr().add(off));
-        let len = vec.len().checked_sub(off).unwrap_or(0);
-        let cap = vec.capacity().checked_sub(off).unwrap_or(0);
+        let ptr = vptr(vec.as_mut_ptr());
+        let len = vec.len();
+        let cap = vec.capacity();
 
-        let original_capacity_repr = original_capacity_to_repr(vec.capacity());
-        let data = (original_capacity_repr << ORIGINAL_CAPACITY_OFFSET)
-            | (off << VEC_POS_OFFSET)
-            | KIND_VEC;
+        let original_capacity_repr = original_capacity_to_repr(cap);
+        let data = (original_capacity_repr << ORIGINAL_CAPACITY_OFFSET) | KIND_VEC;
 
         BytesMut {
             ptr,
@@ -867,7 +860,7 @@ impl BytesMut {
     /// # SAFETY
     ///
     /// The caller must ensure that `count` <= `self.cap`.
-    unsafe fn advance_unchecked(&mut self, count: usize) {
+    pub(crate) unsafe fn advance_unchecked(&mut self, count: usize) {
         // Setting the start to 0 is a no-op, so return early if this is the
         // case.
         if count == 0 {