Tracking issue for syn 2.0 inside rust-lang/rust #109302
Description
syn 2.0 was just released!
https://github.com/dtolnay/syn/releases/tag/2.0.0
We should try to fully eliminate syn 1.0 from our dependency tree for better compile times.
The current ways in which we depend on syn 1:
- [ ] `synstructure` (chalk and yoke) - https://github.com/mystor/synstructure/pull/57 - [x] `rustc_macros` (requires `synstructure` support, #109663) - [x] [`chalk_derive`](https://github.com/rust-lang/chalk/blob/master/chalk-derive/Cargo.toml) (chalk) (requires `synstructure`) https://github.com/rust-lang/chalk/pull/793 - [x] `askama_derive` (used by rustdoc) #109512 - [x] `clap_derive` (used by cargo and several other tools) #110077 - [x] `declare_clippy_lint` https://github.com/rust-lang/rust-clippy/pull/10621 - [ ] `derive_new` (through rustfmt) - https://github.com/nrc/derive-new/pull/61 - [x] `tracing-attributes` (tracing, used in the compiler) https://github.com/tokio-rs/tracing/pull/2516 - [ ] `derive_more` (used in rustc_middle) - https://github.com/JelteF/derive_more/issues/249 - [x] `displaydoc` (used in icu4x) - https://github.com/yaahc/displaydoc/pull/42 - [x] `futures_macro` (dev dep of clippy) #110079 - [ ] `icu_provider_macros`: (icu4x) - [x] `proc-macro-error`: (through clap) - [x] `serde_derive`: (compiletest , cargo and probably more) #110078 - [x] `thiserror-impl`: (gitoxide through cargo) #110081 - [ ] `zerovec-derive`: (used in icu4x) - [ ] `yoke-derive`: (used in icu4x) - [ ] `zerofrom-derive`: (used in icu4x) - [ ] `strum_macros` (spdx, licensing) - [ ] `unic-langid-macros-impl` - [ ] `derivative` (unmaintained) - and a few more
Fixing this involes updating the dependencies once they upgrade or contributing upgrades to them directly.