inconsistent and confusing error message about first argument of `assert!`

[jendrikw]

Code

fn f(x: Result<i8, Box<dyn std::error::Error>>) {
    assert!(x.unwrap(), "expected Ok");      // expected `bool`, found `i8`
    assert!(x.unwrap_err(), "expected Err"); // cannot apply unary operator `!`
}

Current output

error[E0308]: mismatched types
 --> src/lib.rs:2:5
  |
2 |     assert!(x.unwrap(), "expected Ok");      // expected `bool`, found `i8`
  |     ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^ expected `bool`, found `i8`

error[E0600]: cannot apply unary operator `!` to type `Box<dyn std::error::Error>`
 --> src/lib.rs:3:5
  |
3 |     assert!(x.unwrap_err(), "expected Err"); // cannot apply unary operator `!` to type `Box<dyn std::error::Error>`
  |     ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^ cannot apply unary operator `!`
  |
  = note: this error originates in the macro `assert` (in Nightly builds, run with -Z macro-backtrace for more info)

Some errors have detailed explanations: E0308, E0600.
For more information about an error, try `rustc --explain E0308`.

Desired output

No response

Rationale and extra context

The macro assert! is documented as taking a bool as its first parameter. Therefore I suggest the error message be expected `bool`, found `i8` in both cases.

The very different error messages are very confusing, because Result::unwrap and Result::unwrap_err are basically the same. While I understand both error messages, I do not understand why they are different.

Edit: I just realized it's probably because i8 has an implementation of std::ops::Not. Still weird.

Other cases

No response

Rust Version

rustc 1.76.0 (07dca489a 2024-02-04)
binary: rustc
commit-hash: 07dca489ac2d933c78d3c5158e3f43beefeb02ce
commit-date: 2024-02-04
host: x86_64-unknown-linux-gnu
release: 1.76.0
LLVM version: 17.0.6

Anything else?

No response