…p_first, pop_last

…les.

It's tautological, and Rust-specific Jargon.

This changes various Option/Result methods to consistently describe unwrapping
behavior using the words "return", "contain", "consume".

It also renames the closure argument of `Return::unwrap_or_else` to `default` to
be consistent with `Option`.

This reduces the number of `associated_item` queries done here.

Quickly skip impls that do not define any items with the same name

Implement proper C ABI lowering for RISC-V

This is necessary for full RISC-V psABI compliance when passing argument across C FFI boundary.

cc @lenary

…r=KodrAus

Fix and test implementation of BTreeMap's first/last_entry, pop_first/last

Properly implement and test `first_entry` & `last_entry` to fix problem report rust-lang#68829

…agisa

rustc_codegen_llvm: always set AlwaysPreserve on all debuginfo variables

Making this depend on the optimization level appears to have been a copy-paste mistake (other LLVM functions called in this module also take a `bool` argument, but there it means something unrelated).
Also see rust-lang#8855 (comment).

I don't believe we have any reason to let LLVM omit user variables from DWARF, and we were already setting this to `true` when LLVM *could* optimize them away, so this PR should have no effect anyway.

r? @michaelwoerister or @nagisa cc @rkruppe @nikomatsakis

Make the `type_of` return a generic type for generators

Fixes rust-lang#67651.

r? @nikomatsakis

…=petrochenkov

Speed up the inherent impl overlap check

This gives a ~7% improvement in compile times for the stm32f0(x2) crate.

Also addresses @eddyb's comment in rust-lang#68837 (comment).

Pretty-print generic params and where clauses on associated types

closes rust-lang#67509

Don't use the word "unwrap" to describe "unwrap" methods

It's tautological, and "unwrap" is essentially Rust-specific jargon.

I was teaching a newbie some Rust, and doing the usual hand-waving about error handling using unwrap. They asked what 'unwrap' means. I said look it up in the docs. The docs read (paraphrased) "unwrap unwraps". I was embarrassed.

This changes all the Option/Result functions with unwrapping behavior to use a variation on a single description:

> "Returns the contained `Some/Ok` value [or ...]."

It also renames the closure of `Result::unwrap_or_else` to `default` for consistency with `Option`, and perhaps makes a few other small tweaks.

Previous: rust-lang#68849