Metabug for 2018 edition lints

[Manishearth]

Edition lints

These lints will warn by default on Rust 2015.

• Edition keywords Write lint for usage of edition-gated keywords #49716 (blocked on Edition-gated keywords #49611)
  • Hygiene plan: Do this at the lexer level
• fully qualified paths that use module names Add epoch breakage lint for fully qualified paths that do not use crate, self, or super #48722 (PR at Edition breakage lint for absolute paths starting with modules #50100)
  • Hygiene plan: None
• Flipping these on
  • Need support for EpochAllow - edition_lint_opts

Idiom lints

These lints will warn only when you opt in to the 2018 edition, and are useful for driving rustfix to update idioms.

• extern crate extern crate epoch lint for Path Clarity RFC (2126) #48719 (PR at idiom lints for removing extern crate #50260)

Bugs

• Suggestions within macros (Epoch lints don't handle macros very well #48704)

[Manishearth]

cc @aturon @cramertj please fill in details on lints and add more

[aturon]

cc @nikomatsakis

[nrc]

I'm going to close this since there is not much info here, tracking has got too complex for a GH issue, and we can use the A-edition-2018-lints label.