I am going to pick up @eddyb's type-alias PRs, at least the ones that should become hard errors in Rust 2018:

• Too many bounds on a type alias (we need to issue suggestions for T: ?Sized in this case)
• "Global" bounds

The plan is to issue warnings in Rust 2015 and hard errors in Rust 2018, at least for now. "Too few bounds" unfortunately had too many regressions to make into a hard error without some form of migration. We'll tackle that too, but later.

Adding this issue to help us keep track of this.

Question: Do we feel it's an RC2 blocker?