This change consists of cherry-picking the content from the original
PR[1], which got closed due to inactivity, and applying the following
changes:

* Resolving merge conflicts (obviously)
* Linked to to_ipv4_mapped instead of to_ipv4 in the documentation (seems
  more appropriate)
* Added the must_use and rustc_const_unstable attributes the original
  didn't have

I think it's a reasonably useful method.

[1] rust-lang#86490

These tests deliberately use non-standard formatting, so that the line
execution counts reported by `llvm-cov` reveal additional information about
where code regions begin and end.

Some of these tests use non-standard formatting that we can simulate by
strategically adding `//` line comments.

One contains `where` clauses that would be split across multiple lines, which
we can keep on one line by moving the bounds to the generic type instead.

These tests can simply be reformatted as normal, because the resulting changes
are unimportant.

Starting from cargo#13311, Cargo's compiler artifact message
uses Package ID specification as package's identifier format.

…u-se

Implement strict integer operations that panic on overflow

This PR implements the first part of the ACP for adding panic on overflow style arithmetic operations (rust-lang/libs-team#270), mentioned in rust-lang#116064.

It adds the following operations on both signed and unsigned integers:

- `strict_add`
- `strict_sub`
- `strict_mul`
- `strict_div`
- `strict_div_euclid`
- `strict_rem`
- `strict_rem_euclid`
- `strict_neg`
- `strict_shl`
- `strict_shr`
- `strict_pow`

Additionally, signed integers have:

- `strict_add_unsigned`
- `strict_sub_unsigned`
- `strict_abs`

And unsigned integers have:

- `strict_add_signed`

The `div` and `rem` operations are the same as normal division and remainder but are added for completeness similar to the corresponding `wrapping_*` operations.

I'm not sure if I missed any operations, I basically found them from the `wrapping_*` and `checked_*` operations on both integer types.

…Simulacrum

Use `bool` instead of `PartiolOrd` as return value of the comparison closure in `{slice,Iteraotr}::is_sorted_by`

Changes the function signature of the closure given to `{slice,Iteraotr}::is_sorted_by` to return a `bool` instead of a `PartiolOrd` as suggested by the libs-api team here: rust-lang#53485 (comment).

This means these functions now return true if the closure returns true for all the pairs of values.

Add Ipv6Addr::is_ipv4_mapped

This change consists of cherry-picking the content from the original PR[1], which got closed due to inactivity, and applying the following changes:

* Resolving merge conflicts (obviously)
* Linked to to_ipv4_mapped instead of to_ipv4 in the documentation (seems more appropriate)
* Added the must_use and rustc_const_unstable attributes the original didn't have

I think it's a reasonably useful method to have.

[1] rust-lang#86490

…tmiasko

Use an interpreter in MIR jump threading

This allows to understand assignments of aggregate constants. This case appears more frequently with GVN promoting aggregates to constants.

Move OS String implementation into `sys`

Part of rust-lang#117276. The new structure is really useful here, since we can easily eliminate a number of ugly `#[path]`-based imports.

In the future, it might be good to move the WTF-8 implementation directly to the OS string implementation, I cannot see it being used anywhere else. That is a story for another PR, however.

coverage: Format all coverage tests with `rustfmt`

As suggested by <rust-lang#119984 (comment)>.

Test files in `tests/` are normally ignored by `x fmt`, but sometimes those files end up being run through `rustfmt` anyway, either by `rust-analyzer` or by hand.

When that happens, it's annoying to have to manually revert formatting changes that are unrelated to the actual changes being made. So it's helpful for the tests in the repository to already have standard formatting beforehand.

However, there are several coverage tests that deliberately use non-standard formatting, so that line counts reveal more information about where code regions begin and end. In those cases, we can use `#[rustfmt::skip]` to prevent that code from being disturbed.

``@rustbot`` label +A-code-coverage

…compiler-errors

pattern_analysis: Remove `Ty: Copy` bound

To make it compatible with rust-analyzer's `Ty` which isn't `Copy` (it's an `Arc`).

r? ``@compiler-errors``

…acrum

fix(rust-analyzer): use new pkgid spec to compare

Starting from rust-lang/cargo#13311, Cargo's compiler artifact message
uses Package ID specification as package's identifier format.

Zulip topic: https://rust-lang.zulipchat.com/#narrow/stream/246057-t-cargo/topic/proc-macro-test.20bootstrap.20and.20pkgid.20JSON

cc `@ehuss`