mirror of
https://github.com/rust-lang/rust.git
synced 2025-11-28 08:57:13 +00:00
a810f8ac89
Better error message for late/early lifetime param mismatch Rework the way we report early-/late-bound lifetime param mismatches to equate the trait and impl signatures using region variables, so that we can detect when a late-bound param is present in the signature in place of an early-bound param, or vice versa. The diagnostic is a bit more technical, but it's more obviously clear to see what the problem is, even if it's not great at explaining how to fix it. I think this could be improved further, but I still think it's much better than what exists today. Note to reviewer(s): I'd appreciate if we didn't bikeshed *too* much about this verbiage, b/c I hope it's clear that the old message sucked a lot. I'm happy to file bugs for interested new contributors to improve the messaging further. Edit(fmease): Fixes https://github.com/rust-lang/rust/issues/33624.
For high-level intro to how type checking works in rustc, see the type checking chapter of the rustc dev guide.