Fix suggestion on assert! points into the macros definition

[ProgramCrafter]

Code

fn main() {
    let buf = [0_u8; 4];
    assert_ne!(buf, b"----");
}

Current output

error[E0277]: can't compare `[u8; 4]` with `&[u8; 4]`
 --> src/main.rs:3:5
  |
3 |     assert_ne!(buf, b"----");
  |     ^^^^^^^^^^^^^^^^^^^^^^^^ no implementation for `[u8; 4] == &[u8; 4]`
  |
  = help: the trait `PartialEq<&[u8; 4]>` is not implemented for `[u8; 4]`
  = note: this error originates in the macro `assert_ne` (in Nightly builds, run with -Z macro-backtrace for more info)
help: consider dereferencing here
 --> /playground/.rustup/toolchains/nightly-x86_64-unknown-linux-gnu/lib/rustlib/src/rust/library/core/src/macros/mod.rs:102:33
  |
10|                 if *left_val == **right_val {
  |                                 +

Desired output

error[E0277]: can't compare `[u8; 4]` with `&[u8; 4]`
 --> src/main.rs:3:5
  |
3 |     assert_ne!(buf, b"----");
  |     ^^^^^^^^^^^^^^^^^^^^^^^^ no implementation for `[u8; 4] == &[u8; 4]`
  |
  = help: the trait `PartialEq<&[u8; 4]>` is not implemented for `[u8; 4]`
  = note: this error originates in the macro `assert_ne` (in Nightly builds, run with -Z macro-backtrace for more info)
help: consider borrowing here
 --> src/main.rs:3:16
  |
 3|      assert_ne!(&buf, b"----");
  |                 +

Rationale and extra context

The suggestion of fix should not point into internals of standard library.

Other cases

Rust Version

rustc 1.90.0-nightly (430d6eddf 2025-07-25)
binary: rustc
commit-hash: 430d6eddfc6a455ca4a0137c0822a982cccd3b2b
commit-date: 2025-07-25
host: x86_64-unknown-linux-gnu
release: 1.90.0-nightly
LLVM version: 20.1.8


Also reproduces on Playground on stable 1.89.0, on beta 1.90.0-beta.7, on nightly 1.91.0-nightly (2025-09-03 a1208bf765ba783ee4eb).

Anything else?

No response

[joshtriplett]

Ran into this myself, still present on current stable.

cc @estebank, perhaps?

[JohnTitor]

@chenyukang I see you were preparing a fix for this, would you mind opening a PR?

[chenyukang]

@chenyukang I see you were preparing a fix for this, would you mind opening a PR?

Ok, I will take another look at it.