For all of the methods that pick off the first or last element, we can
use subslice patterns to implement them directly, rather than relying on
deeper indexing function calls. At a minimum, this means the generated
code will rely less on inlining for performance, but in some cases it
also optimizes better.

…same line

…'tcx

Use .next() instead of .nth(0) on iterators.

Rename DefKind::Method and TraitItemKind::Method

r? @eddyb, @Centril, or @matthewjasper

cc rust-lang#69498 rust-lang#60163

Use subslice patterns in slice methods

For all of the methods that pick off the first or last element, we can
use subslice patterns to implement them directly, rather than relying on
deeper indexing function calls. At a minimum, this means the generated
code will rely less on inlining for performance, but in some cases it
also optimizes better.

On mismatched delimiters, only point at empty blocks that are in the same line

We point at empty blocks when we have mismatched braces to detect cases where editors auto insert `}` after writing `{`. Gate this to only the case where the entire span is in the same line so we never point at explicitly empty blocks.

…i-obk

Make PlaceRef take just one lifetime

r? @eddyb

Avoid using `unwrap()` in suggestions

Addresses rust-lang#69725, still need a regression test.

r? @estebank

…ited-enum-field, r=oli-obk

Do not ICE when matching an uninhabited enum's field

Fix rust-lang#69191