derivable_impls false positive on array sizes that do not implement Default

[shssoichiro]

Lint name: derivable_impls

I have the following code:

struct RCDeserialize {
  pass2_buffer: [u8; 68],
}

impl Default for RCDeserialize {
  fn default() -> Self {
    RCDeserialize {
      pass2_buffer: [0; 68],
    }
  }
}

I receive this warning:

warning: this `impl` can be derived
   --> src/rate.rs:466:1
    |
466 | / impl Default for RCDeserialize {
467 | |   fn default() -> Self {
468 | |     RCDeserialize {
469 | |       pass2_buffer: [0; 68],
...   |
473 | |   }
474 | | }
    | |_^
    |
    = help: try annotating `rate::RCDeserialize` with `#[derive(Default)]`
    = help: for further information visit https://rust-lang.github.io/rust-clippy/master/index.html#derivable_impls

I try the suggestion:

#[derive(Default)]
struct RCDeserialize {
  pass2_buffer: [u8; 68],
}

I receive the following compiler error:

error[E0277]: the trait bound `[u8; 68]: std::default::Default` is not satisfied
   --> src/rate.rs:464:3
    |
456 | #[derive(Default)]
    |          ------- in this derive macro expansion
...
464 |   pass2_buffer: [u8; 68],
    |   ^^^^^^^^^^^^^^^^^^^^^^ the trait `std::default::Default` is not implemented for `[u8; 68]`
    |
    = help: the following implementations were found:
              <&[T] as std::default::Default>
              <&mut [T] as std::default::Default>
              <[T; 0] as std::default::Default>
              <[T; 10] as std::default::Default>
            and 31 others
note: required by `std::default::Default::default`

Meta

Rust version (rustc -Vv):

rustc 1.57.0-nightly (9dd4ce80f 2021-09-17)
binary: rustc
commit-hash: 9dd4ce80fb01d1ff5cb5002f08b7b3847b59e664
commit-date: 2021-09-17
host: x86_64-unknown-linux-gnu
release: 1.57.0-nightly
LLVM version: 13.0.0

@rustbot label +I-suggestion-causes-error