Make more traits of the From/Into family diagnostic items
Following traits are now diagnostic items:
- `From` (unchanged)
- `Into`
- `TryFrom`
- `TryInto`
This also adds symbols for those items:
- `into_trait`
- `try_from_trait`
- `try_into_trait`
Related: https://github.com/rust-lang/rust-clippy/pull/6620#discussion_r562482587
Add `unwrap_unchecked()` methods for `Option` and `Result`
In particular:
- `unwrap_unchecked()` for `Option`.
- `unwrap_unchecked()` and `unwrap_err_unchecked()` for `Result`.
These complement other `*_unchecked()` methods in `core` etc.
Currently there are a couple of places it may be used inside rustc (`LinkedList`, `BTree`). It is also easy to find other repositories with similar functionality.
Fixes#48278.
Prevent query cycles in the MIR inliner
r? `@eddyb` `@wesleywiser`
cc `@rust-lang/wg-mir-opt`
The general design is that we have a new query that is run on the `validated_mir` instead of on the `optimized_mir`. That query is forced before going into the optimization pipeline, so as to not try to read from a stolen MIR.
The query should not be cached cross crate, as you should never call it for items from other crates. By its very design calls into other crates can never cause query cycles.
This is a pessimistic approach to inlining, since we strictly have more calls in the `validated_mir` than we have in `optimized_mir`, but that's not a problem imo.
More clear documentation for NonNull<T>
Rephrase and hopefully clarify the discussion of covariance in `NonNull<T>` documentation.
I'm very much not an expert so someone should definitely double check the correctness of what I'm saying. At the same time, the new language makes more sense to me, so hopefully it also is more logical to others whose knowledge of covariance basically begins and ends with the [Rustonomicon chapter](https://doc.rust-lang.org/nomicon/subtyping.html).
Related to #48929.
This is a temporary change only, as we wait to resolve dynamic dispatch issues. The `Stream::next` method and corresponding documentation are expected to be fully restored once we have a path to proceed.
Ref: https://github.com/rust-lang/rfcs/pull/2996#issuecomment-757386206
update docs
Change branching in `iter.skip()`
Optimize branching in `Skip`, which was brought up in #80416.
This assumes that if `next` is called, it's likely that there will be more calls to `next`, and the branch for skip will only be hit once thus it's unlikely to take that path. Even w/o the `unlikely` intrinsic, it compiles more efficiently, I believe because the path where `next` is called is always taken.
It should be noted there are very few places in the compiler where `Skip` is used, so probably won't have a noticeable perf impact.
[New impl](https://godbolt.org/z/85rdj4)
[Old impl](https://godbolt.org/z/Wc74rh)
[Some additional asm examples](https://godbolt.org/z/feKzoz) although they really don't have a ton of difference between them.
Following traits are now diagnostic items:
- `From` (unchanged)
- `Into`
- `TryFrom`
- `TryInto`
This also adds symbols for those items:
- `into_trait`
- `try_from_trait`
- `try_into_trait`
Expand docs on Iterator::intersperse
Unstable feature in #79524. This expands on the docs to bring them more in line with how other methods of `Iterator` are demonstrated.
Stability oddity with const intrinsics
cc `@RalfJung`
In https://github.com/rust-lang/rust/pull/80699#discussion_r551495670 `@usbalbin` realized we accepted some intrinsics as `const` without a `#[rustc_const_(un)stable]` attribute. I did some digging, and that example works because intrinsics inherit their stability from their parents... including `#[rustc_const_(un)stable]` attributes. While we may want to fix that (not sure, wasn't there just a MCPed PR that caused this on purpose?), we definitely want tests for it, thus this PR adding tests and some fun tracing statements.
