handle underscore bounds in unexpected places
Per the discussion on #54902, I made it a hard error to use lifetime bounds in various places where they used to be permitted:
- `where Foo: Bar<'_>` for example
I also moved error reporting to HIR lowering and added `Error` variants to let us suppress downstream errors that result.
I (imo) improved the error message wording to be clearer, as well.
In the process, I fixed the ICE in #52098.
Fixes#54902Fixes#52098
Also, avoid shadowing of the `ty` variable by giving the `cast_ty` and
`var_ty` variables different names. We want to get the user-provided
type from `cast_ty.hir_id`.
Add a `copysign` function to f32 and f64
This patch adds a `copysign` function to the float primitive types. It is an exceptionally useful function for writing efficient numeric code, as it often avoids branches, is auto-vectorizable, and there are efficient intrinsics for most platforms.
I think this might work as-is, as the relevant `copysign` intrinsic is already used internally for the implementation of `signum`. It's possible that an implementation might be needed in japaric/libm for portability across all platforms, in which case I'll do that also.
Part of the work towards #55107
Custom E0277 diagnostic for `Path`
r? @nikomatsakis we have a way to target `Path` exclusively, we need to identify the correct text to show to consider #23286 fixed.
NLL lacks various special case handling of closures
Part of #52663.
Firstly, this PR extends existing handling of closures to also support generators.
Second, this PR adds the note found in the AST when a closure is invoked twice and captures a variable by-value:
```text
note: closure cannot be invoked more than once because it moves the variable `dict` out of its environment
--> $DIR/issue-42065.rs:16:29
|
LL | for (key, value) in dict {
| ^^^^
```
r? @nikomatsakis
cc @pnkfelix
This commit extends existing special-casing of closures to highlight the
use of variables within generators that are causing the generator to
borrow them.
Add slice::rchunks(), rchunks_mut(), rchunks_exact() and rchunks_exact_mut()
These work exactly like the normal chunks iterators but start creating
chunks from the end of the slice.
----
The new iterators were motivated by a [comment](https://github.com/rust-lang/rust/issues/47115#issuecomment-424141121) by @DutchGhost.
~~~This currently includes the commits from https://github.com/rust-lang/rust/pull/54537 to not have to rename things twice or have merge conflicts. I'll force-push a new version of the branch ones those are in master.~~~
Also the stabilization tracking issue is just some number right now. I'll create the corresponding issue once this is reviewed and otherwise mergeable.
cc @DutchGhost
