2018 edition lints #52047

Edition lints in the rust_2018_idioms group power Rustfix, the tool for transitioning crates from the 2015 to the 2018 edition. Having a good automatic tool for migrating crates is essential to a successful 2018 edition, and having well-implemented lints is essential to Rustfix actually working.

All issues

rust_2018_compatibility

• keywords (Write lint for usage of edition-gated keywords #49716, some mentoring instructions)
• migrating $()?* macros (2018 edition ? Kleene operator #51587; PR in progress)
  • PR implementing the lint
  • Blocked on FCP being accepted and finishing
• migrating extern crate with #[macro_use] (edition lint: migrating extern crate with #[macro_use] #52043)
• shadowing of extern crates with modules (edition lint: modules shadowing extern crates #52040)
• dyn should not be allowed as a trait name (impl dyn for AnyType fails to compile #50405)
  • decision was to allow this and force impl self::dyn for ... for disambiguation

rust_2018_idioms

• '_ in preference to lifetime elision in types (edition lint: prefer '_ to lifetime elision in types #52041)
• ... to ..= (rewrite ... to ..= as an idiom lint for Rust 2018 edition #51043; partial solution)
• unnecessary T: 'a annotations (edition lint: unnecessary T: 'a annotations #52042)
• declarations obviated by in-band lifetimes (edition lint: declarations obviated by in-band lifetimes #52045)
• prefer crate to pub(crate) (edition lint: prefer crate to pub(crate) #52048)
• suggestion for pub(crate) (add modifier keyword spans to hir::Visibility; improve unreachable-pub, private-no-mangle lint suggestions #51866)
• bare trait objects (i.e., missing dyn)
• unreachable pub
• unused extern crate
• inclusive range patterns (... to ..=)