Why Rust compiler doesn't consider Box<FileRotate<_>> as valid a implementation for Box<(dyn std::io::Write + Send + 'static)?

I am attempting to combine a rotating log with fern, by chaining a boxed FileRotate instance (from file-rotate crate) with a fern Dispatch instance, but can’t seem to satisfy the compiler. Here is the code snippet:

let log= Box::new(
    FileRotate::new(
        "log/output.log",
        CountSuffix::new(2),
        ContentLimit::Lines(10),
        Compression::None));

fern::Dispatch::new()
    .level(LevelFilter::Debug)
    .chain(log)
    .apply()?;

The compiler disagrees, with the following error:

error[E0277]: the trait bound `fern::Output: From<Box<FileRotate<CountSuffix>>>` is not satisfied
   --> src/main.rs:101:16
    |
101 |         .chain(log)
    |          ----- ^^^ the trait `From<Box<FileRotate<CountSuffix>>>` is not implemented for `fern::Output`
    |          |
    |          required by a bound introduced by this call
    |
    = help: the following implementations were found:
              <fern::Output as From<&'static (dyn log::Log + 'static)>>
              <fern::Output as From<Box<(dyn log::Log + 'static)>>>
              <fern::Output as From<Box<(dyn std::io::Write + Send + 'static)>>>
              <fern::Output as From<Dispatch>>
            and 6 others
    = note: required because of the requirements on the impl of `Into<fern::Output>` for `Box<FileRotate<CountSuffix>>`
note: required by a bound in `Dispatch::chain`
   --> /Users/l203663/.cargo/registry/src/github.com-1ecc6299db9ec823/fern-0.6.0/src/builders.rs:195:21
    |
195 |     pub fn chain<T: Into<Output>>(mut self, logger: T) -> Self {
    |                     ^^^^^^^^^^^^ required by this bound in `Dispatch::chain`

However, the FileRotate struct implements both Write and Send, as documented here and here.

The closest implementation proposed by the compiler is IMO:

From<Box<(dyn std::io::Write + Send + 'static)>

• Is the issue caused by the 'static lifetime? In which case, how could I solve this?
• If not, what could possibly cause the issue?

Crates in use:

log = "0.4.14"
fern = "0.6.0"
file-rotate = "0.5.3" 

>Solution :

I am not certain that this is all of the problem (not having used fern) but since the input parameter to chain() is generic, it won’t automatically coerce your Box<FileRotate> to a Box<dyn Write + Send>, so you have to do that explicitly:

.chain(log as Box<dyn Write + Send>)

You do not need to specify 'static because that is the default for all Box<dyn ...> (but not &dyn ...).