`tracing` 0.1.42 breaks unqualified use of `debug` and `display` in macros

[hds]

Bug Report

Up to tracing 0.1.41, this works:

    let foo = Some(42);
    let bar = true;

    tracing::info!(foo = debug(foo), bar = display(bar));

However, from tracing 0.1.42 (due to #3382), it fails to compile:

error[E0425]: cannot find function `debug` in this scope
  --> src/main.rs:12:26
   |
12 |     tracing::info!(foo = debug(foo), bar = display(bar));
   |                          ^^^^^ not found in this scope
   |
help: consider importing this function
   |
 1 + use tracing::field::debug;
   |

error[E0425]: cannot find function `display` in this scope
  --> src/main.rs:12:44
   |
12 |     tracing::info!(foo = debug(foo), bar = display(bar));
   |                                            ^^^^^^^ not found in this scope
   |
help: consider importing this function
   |
 1 + use tracing::field::display;
   |

For more information about this error, try `rustc --explain E0425`.

Version

• tracing 0.1.42

Platform

all

Crates

• tracing

Notes

Release train: #3413
Release PR: #3418

[hds]

I've yanked tracing 0.1.42.

Will prepare a revert tomorrow (it can't be done automatically due to other changes in the macros) and then prepare a new release.

[geofmureithi]

Some of us were too eager to update 😆

[geofmureithi]

I thing tracing-subscriber is also broken:

error: failed to select a version for the requirement `tracing = "^0.1.42"`
  version 0.1.42 is yanked
location searched: crates.io index
required by package `tracing-subscriber v0.3.21`
    ... which satisfies dependency `tracing-subscriber = "^0.3.21"`

[hds]

I still can't reproduce this issue, but obviously it's there. As such I've also yanked:

• tracing-subscriber 0.3.21
• tracing-mock 0.1.0-beta.2

[hawkw]

I would like to point out that removing the implicit imports has been proposed in the past, and we've historically chosen not to do to avoid the breaking change. The issue (#3381) that PR #3382 was intended to fix was closed when @mladedav pointed out that "fixing" it would break existing uses: #3381 (comment)

[hds]

Yeah, that's my bad. I didn't read all the comments on the Issue closely enough, clearly.

[mladedav]

For completeness, here is even older description of this with a link to the PR 5 years ago where something like this was already merged and then reverted with more context and discussion.

[hds]

This is still our best hope: #2332 (comment)