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suppress needless_lifetimes lints from clippy 0.1.83#391

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dtolnay merged 1 commit intodtolnay:masterfrom
matt-phylum:needless-lifetimes
Dec 3, 2024
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suppress needless_lifetimes lints from clippy 0.1.83#391
dtolnay merged 1 commit intodtolnay:masterfrom
matt-phylum:needless-lifetimes

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I think I did this correctly.

In Clippy 0.1.83, without the changes in expand.rs, the new test in test_lints.rs fails with the following output:

error: the following explicit lifetimes could be elided: 'a
  --> tests/test_lints.rs:29:22
   |
29 |     pub enum MyError<'a> {
   |                      ^^
   |
   = help: for further information visit https://rust-lang.github.io/rust-clippy/master/index.html#needless_lifetimes
note: the lint level is defined here
  --> tests/test_lints.rs:25:13
   |
25 |     #![deny(clippy::needless_lifetimes)]
   |             ^^^^^^^^^^^^^^^^^^^^^^^^^^
help: elide the lifetimes
   |
29 -     pub enum MyError<'a> {
29 +     pub enum MyError'_> {
   |

error: could not compile `thiserror` (test "test_lints") due to 1 previous error

Clippy doesn't like the generated impl From and gets confused about what it's fixing (rust-lang/rust-clippy#12789?) and the result is a confusing message suggesting code that is broken in multiple ways. The Display and Error impls don't seem to be affected, so this probably only affects users that use borrowed errors and #[from].

I encountered this in a project I can't share, but it's the same case as ruffle-rs/ruffle#18761 https://github.com/ruffle-rs/ruffle/blob/bd89e5b216769168d08548f01e2b6871280ab829/core/src/avm1/error.rs

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Thanks!

@dtolnay dtolnay merged commit 4fde284 into dtolnay:master Dec 3, 2024
jimsynz pushed a commit to jimsynz/outrun that referenced this pull request Oct 13, 2025
This PR contains the following updates:

| Package | Type | Update | Change |
|---|---|---|---|
| [thiserror](https://github.com/dtolnay/thiserror) | dependencies | major | `1.0` -> `2.0` |

---

### Release Notes

<details>
<summary>dtolnay/thiserror (thiserror)</summary>

### [`v2.0.17`](https://github.com/dtolnay/thiserror/releases/tag/2.0.17)

[Compare Source](dtolnay/thiserror@2.0.16...2.0.17)

- Use differently named \_\_private module per patch release ([#&#8203;434](dtolnay/thiserror#434))

### [`v2.0.16`](https://github.com/dtolnay/thiserror/releases/tag/2.0.16)

[Compare Source](dtolnay/thiserror@2.0.15...2.0.16)

- Add to "no-std" crates.io category ([#&#8203;429](dtolnay/thiserror#429))

### [`v2.0.15`](https://github.com/dtolnay/thiserror/releases/tag/2.0.15)

[Compare Source](dtolnay/thiserror@2.0.14...2.0.15)

- Prevent `Error::provide` API becoming unavailable from a future new compiler lint ([#&#8203;427](dtolnay/thiserror#427))

### [`v2.0.14`](https://github.com/dtolnay/thiserror/releases/tag/2.0.14)

[Compare Source](dtolnay/thiserror@2.0.13...2.0.14)

- Allow build-script cleanup failure with NFSv3 output directory to be non-fatal ([#&#8203;426](dtolnay/thiserror#426))

### [`v2.0.13`](https://github.com/dtolnay/thiserror/releases/tag/2.0.13)

[Compare Source](dtolnay/thiserror@2.0.12...2.0.13)

- Documentation improvements

### [`v2.0.12`](https://github.com/dtolnay/thiserror/releases/tag/2.0.12)

[Compare Source](dtolnay/thiserror@2.0.11...2.0.12)

- Prevent elidable\_lifetime\_names pedantic clippy lint in generated impl ([#&#8203;413](dtolnay/thiserror#413))

### [`v2.0.11`](https://github.com/dtolnay/thiserror/releases/tag/2.0.11)

[Compare Source](dtolnay/thiserror@2.0.10...2.0.11)

- Add feature gate to tests that use std ([#&#8203;409](dtolnay/thiserror#409), [#&#8203;410](dtolnay/thiserror#410), thanks [@&#8203;Maytha8](https://github.com/Maytha8))

### [`v2.0.10`](https://github.com/dtolnay/thiserror/releases/tag/2.0.10)

[Compare Source](dtolnay/thiserror@2.0.9...2.0.10)

- Support errors containing a generic type parameter's associated type in a field ([#&#8203;408](dtolnay/thiserror#408))

### [`v2.0.9`](https://github.com/dtolnay/thiserror/releases/tag/2.0.9)

[Compare Source](dtolnay/thiserror@2.0.8...2.0.9)

- Work around `missing_inline_in_public_items` clippy restriction being triggered in macro-generated code ([#&#8203;404](dtolnay/thiserror#404))

### [`v2.0.8`](https://github.com/dtolnay/thiserror/releases/tag/2.0.8)

[Compare Source](dtolnay/thiserror@2.0.7...2.0.8)

- Improve support for macro-generated `derive(Error)` call sites ([#&#8203;399](dtolnay/thiserror#399))

### [`v2.0.7`](https://github.com/dtolnay/thiserror/releases/tag/2.0.7)

[Compare Source](dtolnay/thiserror@2.0.6...2.0.7)

- Work around conflict with #\[deny(clippy::allow\_attributes)] ([#&#8203;397](dtolnay/thiserror#397), thanks [@&#8203;zertosh](https://github.com/zertosh))

### [`v2.0.6`](https://github.com/dtolnay/thiserror/releases/tag/2.0.6)

[Compare Source](dtolnay/thiserror@2.0.5...2.0.6)

- Suppress deprecation warning on generated From impls ([#&#8203;396](dtolnay/thiserror#396))

### [`v2.0.5`](https://github.com/dtolnay/thiserror/releases/tag/2.0.5)

[Compare Source](dtolnay/thiserror@2.0.4...2.0.5)

- Prevent deprecation warning on generated impl for deprecated type ([#&#8203;394](dtolnay/thiserror#394))

### [`v2.0.4`](https://github.com/dtolnay/thiserror/releases/tag/2.0.4)

[Compare Source](dtolnay/thiserror@2.0.3...2.0.4)

- Eliminate needless\_lifetimes clippy lint in generated `From` impls ([#&#8203;391](dtolnay/thiserror#391), thanks [@&#8203;matt-phylum](https://github.com/matt-phylum))

### [`v2.0.3`](https://github.com/dtolnay/thiserror/releases/tag/2.0.3)

[Compare Source](dtolnay/thiserror@2.0.2...2.0.3)

- Support the same Path field being repeated in both Debug and Display representation in error message ([#&#8203;383](dtolnay/thiserror#383))
- Improve error message when a format trait used in error message is not implemented by some field ([#&#8203;384](dtolnay/thiserror#384))

### [`v2.0.2`](https://github.com/dtolnay/thiserror/releases/tag/2.0.2)

[Compare Source](dtolnay/thiserror@2.0.1...2.0.2)

- Fix hang on invalid input inside #\[error(...)] attribute ([#&#8203;382](dtolnay/thiserror#382))

### [`v2.0.1`](https://github.com/dtolnay/thiserror/releases/tag/2.0.1)

[Compare Source](dtolnay/thiserror@2.0.0...2.0.1)

- Support errors that contain a dynamically sized final field ([#&#8203;375](dtolnay/thiserror#375))
- Improve inference of trait bounds for fields that are interpolated multiple times in an error message ([#&#8203;377](dtolnay/thiserror#377))

### [`v2.0.0`](https://github.com/dtolnay/thiserror/releases/tag/2.0.0)

[Compare Source](dtolnay/thiserror@1.0.69...2.0.0)

##### Breaking changes

- Referencing keyword-named fields by a raw identifier like `{r#type}` inside a format string is no longer accepted; simply use the unraw name like `{type}` ([#&#8203;347](dtolnay/thiserror#347))

  This aligns thiserror with the standard library's formatting macros, which gained support for implicit argument capture later than the release of this feature in thiserror 1.x.

  ```rust
  #[derive(Error, Debug)]
  #[error("... {type} ...")]  // Before: {r#type}
  pub struct Error {
      pub r#type: Type,
  }
  ```

- Trait bounds are no longer inferred on fields whose value is shadowed by an explicit named argument in a format message ([#&#8203;345](dtolnay/thiserror#345))

  ```rust
  // Before: impl<T: Octal> Display for Error<T>
  // After: impl<T> Display for Error<T>
  #[derive(Error, Debug)]
  #[error("{thing:o}", thing = "...")]
  pub struct Error<T> {
      thing: T,
  }
  ```

- Tuple structs and tuple variants can no longer use numerical `{0}` `{1}` access at the same time as supplying extra positional arguments for a format message, as this makes it ambiguous whether the number refers to a tuple field vs a different positional arg ([#&#8203;354](dtolnay/thiserror#354))

  ```rust
  #[derive(Error, Debug)]
  #[error("ambiguous: {0} {}", $N)]
  //                  ^^^ Not allowed, use #[error("... {0} {n}", n = $N)]
  pub struct TupleError(i32);
  ```

- Code containing invocations of thiserror's `derive(Error)` must now have a direct dependency on the `thiserror` crate regardless of the error data structure's contents ([#&#8203;368](dtolnay/thiserror#368), [#&#8203;369](dtolnay/thiserror#369), [#&#8203;370](dtolnay/thiserror#370), [#&#8203;372](dtolnay/thiserror#372))

##### Features

- Support disabling thiserror's standard library dependency by disabling the default "std" Cargo feature: `thiserror = { version = "2", default-features = false }` ([#&#8203;373](dtolnay/thiserror#373))

- Support using `r#source` as field name to opt out of a field named "source" being treated as an error's `Error::source()` ([#&#8203;350](dtolnay/thiserror#350))

  ```rust
  #[derive(Error, Debug)]
  #[error("{source} ==> {destination}")]
  pub struct Error {
      r#source: char,
      destination: char,
  }

  let error = Error { source: 'S', destination: 'D' };
  ```

- Infinite recursion in a generated Display impl now produces an `unconditional_recursion` warning ([#&#8203;359](dtolnay/thiserror#359))

  ```rust
  #[derive(Error, Debug)]
  #[error("??? {self}")]
  pub struct Error;
  ```

- A new attribute `#[error(fmt = path::to::myfmt)]` can be used to write formatting logic for an enum variant out-of-line ([#&#8203;367](dtolnay/thiserror#367))

  ```rust
  #[derive(Error, Debug)]
  pub enum Error {
      #[error(fmt = demo_fmt)]
      Demo { code: u16, message: Option<String> },
  }

  fn demo_fmt(code: &u16, message: &Option<String>, formatter: &mut fmt::Formatter) -> fmt::Result {
      write!(formatter, "{code}")?;
      if let Some(msg) = message {
          write!(formatter, " - {msg}")?;
      }
      Ok(())
  }
  ```

- Enums with an enum-level format message are now able to have individual variants that are `transparent` to supersede the enum-level message ([#&#8203;366](dtolnay/thiserror#366))

  ```rust
  #[derive(Error, Debug)]
  #[error("my error {0}")]
  pub enum Error {
      Json(#[from] serde_json::Error),
      Yaml(#[from] serde_yaml::Error),
      #[error(transparent)]
      Other(#[from] anyhow::Error),
  }
  ```

</details>

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takumi-earth pushed a commit to earthlings-dev/thiserror that referenced this pull request Jan 27, 2026
suppress needless_lifetimes lints from clippy 0.1.83
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