#[instrument] breaks compilation of functions with argument named debug or display

[sersorrel]

Bug Report

Version

│   │   ├── tracing-core v0.1.17
│   │   └── tracing-error v0.1.2
│   │       ├── tracing v0.1.22
│   │       │   ├── tracing-attributes v0.1.11 (proc-macro)
│   │       │   └── tracing-core v0.1.17 (*)
│   │       └── tracing-subscriber v0.2.15
│   │           └── tracing-core v0.1.17 (*)
│   └── tracing-error v0.1.2 (*)
└── tracing v0.1.22 (*)

Platform

Linux what 4.15.0-139-generic #143-Ubuntu SMP Tue Mar 16 01:30:17 UTC 2021 x86_64 x86_64 x86_64 GNU/Linux

Description

Trying to #[instrument] a function which takes a debug or display parameter causes a compilation error.

For example, this:

use tracing::instrument;

#[instrument]
fn foo(display: ()) {
    println!("{:?}", display);
}

fn main() {
    foo(());
}

results in the following error:

error[E0277]: `fn(_) -> DisplayValue<_> {display::<_>}` doesn't implement `Debug`
   --> src/main.rs:3:1
    |
3   | #[instrument]
    | ^^^^^^^^^^^^^ `fn(_) -> DisplayValue<_> {display::<_>}` cannot be formatted using `{:?}` because it doesn't implement `Debug`
    | 
   ::: /playground/.cargo/registry/src/github.com-1ecc6299db9ec823/tracing-core-0.1.17/src/field.rs:266:8
    |
266 |     T: fmt::Debug,
    |        ---------- required by this bound in `debug`
    |
    = help: the trait `Debug` is not implemented for `fn(_) -> DisplayValue<_> {display::<_>}`
    = note: required because of the requirements on the impl of `Debug` for `&fn(_) -> DisplayValue<_> {display::<_>}`
    = note: this error originates in an attribute macro (in Nightly builds, run with -Z macro-backtrace for more info)

(playground link)

Possibly related: #805

[hawkw]

See also #2332.