…-cov`

…ed -Z unstable-options` to shorten symbol names by replacing them with a digest.

Enrich test cases

It looks like none of these are actually needed.

Also add tests for min-system-llvm-version.

Signed-off-by: Ryan Levick <me@ryanlevick.com>

Co-authored-by: David Wood <agile.lion3441@fuligin.ink>

… r=joshtriplett

[style edition 2024] Combine all delimited exprs as last argument

Closes rust-lang/style-team#149

If this is merged, the rustfmt option `overflow_delimited_expr` should be enabled by default in style edition 2024.

[Rendered](https://github.com/pitaj/rust/blob/style-delimited-expressions/src/doc/style-guide/src/expressions.md#combinable-expressions)

r? joshtriplett

…tmcm

Add `NonZero*::count_ones`

This PR adds the following APIs to the standard library:

```rust
impl NonZero* {
    pub const fn count_ones(self) -> NonZeroU32;
}
```

This is potentially interesting, given that `count_ones` can't ever return 0.

r? libs-api

Add the unstable option  to reduce the binary size of dynamic library…

# Motivation

The average length of symbol names in the rust standard library is about 100 bytes, while the average length of symbol names in the C++ standard library is about 65 bytes. In some embedded environments where dynamic library are widely used, rust dynamic library symbol name space hash become one of the key bottlenecks of application, Especially when the existing C/C++ module is reconstructed into the rust module.

The unstable option `-Z symbol_mangling_version=hashed` is added to solve the bottleneck caused by too long dynamic library symbol names.

## Test data

The following is a set of test data on the ubuntu 18.04 LTS environment. With this plug-in, the space saving rate of dynamic libraries can reach about 20%.

The test object is the standard library of rust (built based on Xargo), tokio crate, and hyper crate.

The contents of the Cargo.toml file in the construction project of the three dynamic libraries are as follows:

```txt
# Cargo.toml
[profile.release]
panic = "abort"
opt-leve="z"
codegen-units=1
strip=true
debug=true
```
The built dynamic library also removes the `.rustc` segments that are not needed at run time and then compares the size. The detailed data is as follows:

1. libstd.so
> | symbol_mangling_version | size | saving rate |
> | --- | --- | --- |
> | legacy | 804896 ||
> | hashed | 608288 | 0.244 |
> | v0 | 858144 ||
> | hashed | 608288 | 0.291 |

2. libhyper.so
> | symbol_mangling_version(libhyper.so) | symbol_mangling_version(libstd.so) | size | saving rate |
> | --- | --- | --- | --- |
> | legacy | legacy | 866312 ||
> | hashed | legacy | 645128 |0.255|
> | legacy | hashed | 854024 ||
> | hashed | hashed | 632840 |0.259|

…wiser

coverage: Never emit improperly-ordered coverage regions

If we emit a coverage region that is improperly ordered (end < start), `llvm-cov` will fail with `coveragemap_error::malformed`, which is inconvenient for users and also very hard to debug.

Ideally we would fix the root causes of these situations, but they tend to occur in very obscure edge-case scenarios (often involving nested macros), and we don't always have a good MCVE to work from. So it makes sense to also have a catch-all check that will prevent improperly-ordered regions from ever being emitted.

---

This is mainly aimed at resolving rust-lang#119453. We don't have a specific way to reproduce it, which is why I haven't been able to add a test case in this PR. But based on the information provided in that issue, this change seems likely to avoid the error in `llvm-cov`.

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

…ochenkov,m-ou-se

Add a new `wasm32-wasi-preview2` target

This is the initial implementation of the MCP rust-lang/compiler-team#694 creating a new tier 3 target `wasm32-wasi-preview2`. That MCP has been seconded and will most likely be approved in a little over a week from now. For more information on the need for this target, please read the [MCP](rust-lang/compiler-team#694).

There is one aspect of this PR that will become insta-stable once these changes reach a stable compiler:
* A new `target_family` named `wasi` is introduced. This target family incorporates all wasi targets including `wasm32-wasi` and its derivative `wasm32-wasi-preview1-threads`. The difference between `target_family = wasi` and `target_os = wasi` will become much clearer when `wasm32-wasi` is renamed to `wasm32-wasi-preview1` and the `target_os` becomes `wasm32-wasi-preview1`. You can read about this target rename in [this MCP](rust-lang/compiler-team#695) which has also been seconded and will hopefully be officially approved soon.

Additional technical details include:
* Both `std::sys::wasi_preview2` and `std::os::wasi_preview2` have been created and mostly use `#[path]` annotations on their submodules to reach into the existing `wasi` (soon to be `wasi_preview1`) modules. Over time the differences between `wasi_preview1` and `wasi_preview2` will grow and most like all `#[path]` based module aliases will fall away.
* Building `wasi-preview2` relies on a [`wasi-sdk`](https://github.com/WebAssembly/wasi-sdk) in the same way that `wasi-preview1` does (one must include a `wasi-root` path in the `Config.toml` pointing to sysroot included in the wasi-sdk). The target should build against [wasi-sdk v21](https://github.com/WebAssembly/wasi-sdk/releases/tag/wasi-sdk-21) without modifications. However, the wasi-sdk itself is growing [preview2 support](WebAssembly/wasi-sdk#370) so this might shift rapidly. We will be following along quickly to make sure that building the target remains possible as the wasi-sdk changes.
* This requires a [patch to libc](https://github.com/rylev/rust-libc/tree/wasm32-wasi-preview2) that we'll need to land in conjunction with this change. Until that patch lands the target won't actually build.

coverage: Don't instrument `#[automatically_derived]` functions

This PR makes the coverage instrumentor detect and skip functions that have [`#[automatically_derived]`](https://doc.rust-lang.org/reference/attributes/derive.html#the-automatically_derived-attribute) on their enclosing impl block.

Most notably, this means that methods generated by built-in derives (e.g. `Clone`, `Debug`, `PartialEq`) are now ignored by coverage instrumentation, and won't appear as executed or not-executed in coverage reports.

This is a noticeable change in user-visible behaviour, but overall I think it's a net improvement. For example, we've had a few user requests for this sort of change (e.g. rust-lang#105055, rust-lang#84605 (comment)), and I believe it's the behaviour that most users will expect/prefer by default.

It's possible to imagine situations where users would want to instrument these derived implementations, but I think it's OK to treat that as an opportunity to consider adding more fine-grained option flags to control the details of coverage instrumentation, while leaving this new behaviour as the default.

(Also note that while `-Cinstrument-coverage` is a stable feature, the exact details of coverage instrumentation are allowed to change. So we *can* make this change; the main question is whether we *should*.)

Fixes rust-lang#105055.

Remove no-system-llvm

We currently have a bunch of codegen tests that use no-system-llvm -- however, all of those tests also pass with system LLVM 16.

I've opted to remove `no-system-llvm` entirely, as there's basically no valid use case for it anymore:

 * The only thing this option could have legitimately been used for (testing the target feature support that requires an LLVM patch) doesn't use it, and the need for this will go away with LLVM 18 anyway.
 * In cases where the test depends on optimizations/fixes from newer LLVM versions, `min-llvm-version` should be used instead.
 * In case it depends on optimization/fixes from newer LLVM versions that have been backported into our fork, `min-system-llvm-version` (with the major version larger than the one in our fork) should be used instead.

r? ````@cuviper````

privacy: Refactor top-level visiting in `TypePrivacyVisitor`

Full hierarchical visiting (`nested_filter::All`) is not necessary, visiting all item-likes in isolation is enough.
Tracking current item is not necessary, just keeping the current `mod` item is enough.
`visit_generic_arg` should behave like its default version, including checking types of const arguments.
Some comments, including FIXMEs, are also added.

Noticed while reading code to review rust-lang#113671.
r? `@oli-obk`

Remove extra # from url in suggestion

The suggestion added in rust-lang#119805 contains an unnecessary # hash sign.

…pdate, r=davidtwco

Add mw to review rotation and add some owner assignments

I've also added a `debuginfo` group and fixed the ownership assignment for the `incremental` group. I hope I got the syntax right.

r? `@davidtwco`