possible regression: expected value, found module `self`

[ignatenkobrain]

serde 0.8 fails to build with

---- src/ser/mod.rs - ser::Serializer::serialize_bytes (line 175) stdout ----
	error[E0424]: expected value, found module `self`
 --> src/ser/mod.rs:176:22
  |
3 | let mut state = try!(self.serialize_seq(value));
  |                      ^^^^ `self` value is only available in methods with `self` parameter
error[E0425]: cannot find value `value` in this scope
 --> src/ser/mod.rs:176:41
  |
3 | let mut state = try!(self.serialize_seq(value));
  |                                         ^^^^^ not found in this scope
error[E0425]: cannot find value `value` in this scope
 --> src/ser/mod.rs:177:10
  |
4 | for b in value {
  |          ^^^^^ not found in this scope
error[E0424]: expected value, found module `self`
 --> src/ser/mod.rs:178:10
  |
5 |     try!(self.serialize_seq_elt(&mut state, b));
  |          ^^^^ `self` value is only available in methods with `self` parameter
error[E0424]: expected value, found module `self`
 --> src/ser/mod.rs:180:1
  |
7 | self.serialize_seq_end(state)
  | ^^^^ `self` value is only available in methods with `self` parameter
error[E0308]: mismatched types
 --> src/ser/mod.rs:176:17
  |
3 | let mut state = try!(self.serialize_seq(value));
  |                 ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^ expected (), found enum `std::result::Result`
  |
  = note: expected type `()`
             found type `std::result::Result<_, _>`
  = note: this error originates in a macro outside of the current crate (in Nightly builds, run with -Z external-macro-backtrace for more info)

This is coming from doctest, so I'm not sure if it's a regression or expected behavior:

    /// Enables serializers to serialize byte slices more compactly or more
    /// efficiently than other types of slices. If no efficient implementation
    /// is available, a reasonable implementation would be to forward to
    /// `serialize_seq`. If forwarded, the implementation looks usually just like this:
    /// ```rust
    /// let mut state = try!(self.serialize_seq(value));
    /// for b in value {
    ///     try!(self.serialize_seq_elt(&mut state, b));
    /// }
    /// self.serialize_seq_end(state)
    /// ```
    fn serialize_bytes(&mut self, value: &[u8]) -> Result<(), Self::Error>;

[ishitatsuyuki]

Duplicate of #28712.

Working as intended.

[SergioBenitez]

This is not a duplicate of #28712. They aren't related, except that the code block should be separated for rustdoc to run it.

Nonetheless, that code block isn't valid Rust, so it won't compile regardless. That is, the error message is correct.