Documentation for checked shifts is misleading

[mateon1]

Excerpt from the CheckedShl trait:

///Performs a left shift that returns `None` on overflow.
pub trait CheckedShl: Sized + Shl<u32, Output=Self> {
    /// Shifts a number to the left, checking for overflow. If overflow happens,
    /// `None` is returned.
...
    fn checked_shl(&self, rhs: u32) -> Option<Self>;

The current wording seems to imply that if bits are shifted past the integer's range, then None is returned. This is not the case, the primitive checked_shl explicitly documents this:

        /// Checked shift left. Computes `self << rhs`, returning `None`
        /// if `rhs` is larger than or equal to the number of bits in `self`.
...
        #[stable(feature = "wrapping", since = "1.7.0")]
        #[inline]
        pub fn checked_shl(self, rhs: u32) -> Option<Self> {
            let (a, b) = self.overflowing_shl(rhs);
            if b {None} else {Some(a)}
        }

None is only returned if rhs is larger than the number of bits in the numeric type.
E.g.

0x88u8.checked_shl(4) == Some(0x80)
0x88u8.cheched_shl(8) == None

[cuviper]

Right, it's an overflow in the number of bits being shifted, regardless of the value involved. Would you like to send a PR to clarify this?