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Rollup of 8 pull requests #120359

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Successful merges:

r? @ghost
@rustbot modify labels: rollup

Create a similar rollup

mbrubeck and others added 21 commits January 4, 2024 13:08
the linker arguments can be *very* long, especially for crates with many dependencies. often they are not useful. omit them unless the user specifically requests them.
On ELF, the text section is opened with ".text", on MachO with
".section __TEXT,__text".

Previously, on ELF this test was actually matching a GNU note
section, which is no longer emitted on Solaris starting with
LLVM 18.

Fixes rust-lang#120105.
… r=compiler-errors

Add the `min_exhaustive_patterns` feature gate

## Motivation

Pattern-matching on empty types is tricky around unsafe code. For that reason, current stable rust conservatively requires arms for empty types in all but the simplest case. It has long been the intention to allow omitting empty arms when it's safe to do so. The [`exhaustive_patterns`](rust-lang#51085) feature allows the omission of all empty arms, but hasn't been stabilized because that was deemed dangerous around unsafe code.

## Proposal

This feature aims to stabilize an uncontroversial subset of exhaustive_patterns. Namely: when `min_exhaustive_patterns` is enabled and the data we're matching on is guaranteed to be valid by rust's operational semantics, then we allow empty arms to be omitted. E.g.:

```rust
let x: Result<T, !> = foo();
match x { // ok
    Ok(y) => ...,
}
let Ok(y) = x; // ok
```

If the place is not guaranteed to hold valid data (namely ptr dereferences, ref dereferences (conservatively) and union field accesses), then we keep stable behavior i.e. we (usually) require arms for the empty cases.

```rust
unsafe {
    let ptr: *const Result<u32, !> = ...;
    match *ptr {
        Ok(x) => { ... }
        Err(_) => { ... } // still required
    }
}
let foo: Result<u32, &!> = ...;
match foo {
    Ok(x) => { ... }
    Err(&_) => { ... } // still required because of the dereference
}
unsafe {
    let ptr: *const ! = ...;
    match *ptr {} // already allowed on stable
}
```

Note that we conservatively consider that a valid reference can point to invalid data, hence we don't allow arms of type `&!` and similar cases to be omitted. This could eventually change depending on [opsem decisions](rust-lang/unsafe-code-guidelines#413). Whenever opsem is undecided on a case, we conservatively keep today's stable behavior.

I proposed this behavior in the [`never_patterns`](rust-lang#118155) feature gate but it makes sense on its own and could be stabilized more quickly. The two proposals nicely complement each other.

## Unresolved Questions

Part of the question is whether this requires an RFC. I'd argue this doesn't need one since there is no design question beyond the intent to omit unreachable patterns, but I'm aware the problem can be framed in ways that require design (I'm thinking of the [original never patterns proposal](https://smallcultfollowing.com/babysteps/blog/2018/08/13/never-patterns-exhaustive-matching-and-uninhabited-types-oh-my/), which would frame this behavior as "auto-nevering" happening).

EDIT: I initially proposed a future-compatibility lint as part of this feature, I don't anymore.
show linker output even if the linker succeeds

- show stderr by default
- show stdout if `--verbose` is passed
- remove both from RUSTC_LOG
- hide the linker cli args unless `--verbose` is passed

fixes rust-lang#83436. fixes rust-lang#38206. fixes rust-lang#109979. helps with rust-lang#46998. cc https://rust-lang.zulipchat.com/#narrow/stream/233931-t-compiler.2Fmajor-changes/topic/uplift.20some.20-Zverbose.20calls.20and.20rename.20to.E2.80.A6.20compiler-team.23706/near/408986134

this is based on rust-lang#119129 for convenience so i didn't have to duplicate the changes around saving `--verbose` in rust-lang@cb6d033#diff-7a49efa20548d6806dbe1c66dd4dc445fda18fcbbf1709520cadecc4841aae12

r? `@bjorn3`
…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.
Split assembly tests for ELF and MachO

On ELF, the text section is opened with ".text", on MachO with ".section __TEXT,__text".

Previously, on ELF this test was actually matching a GNU note section, which is no longer emitted on Solaris starting with LLVM 18.

Fixes rust-lang#120105.

r? `@davidtwco`
Bump some deps with syn 1.0 dependencies

cc rust-lang#109302

`cargo update`ing `unic-langid` and `object` removes two dependencies on Syn 1.0.
…_for_builtin, r=petrochenkov

Builtin macros effectively have implicit #[collapse_debuginfo(yes)]

If collapse_debuginfo attribute for builtin macro is not specified explicitly, it will be effectively set to `#[collapse_debuginfo(yes)]`.
…c-closures, r=oli-obk

Don't manually resolve async closures in `rustc_resolve`

There's a comment here that talks about doing this "[so] closure [args] are detected as upvars rather than normal closure arg usages", but we do upvar analysis on the HIR now:

https://github.com/rust-lang/rust/blob/cd6d8f2a04528f827ad3d399581c0f3502b15a72/compiler/rustc_passes/src/upvars.rs#L21-L29

Removing this ad-hoc logic makes it so that `async |x: &str|` now introduces an implicit binder, like regular closures.

r? `@oli-obk`
Fix broken markdown in csky-unknown-linux-gnuabiv2.md
@rustbot rustbot added A-testsuite Area: The testsuite used to check the correctness of rustc A-translation Area: Translation infrastructure, and migrating existing diagnostics to SessionDiagnostic S-waiting-on-review Status: Awaiting review from the assignee but also interested parties. T-bootstrap Relevant to the bootstrap subteam: Rust's build system (x.py and src/bootstrap) T-compiler Relevant to the compiler team, which will review and decide on the PR/issue. rollup A PR which is a rollup labels Jan 26, 2024
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@bors r+ rollup=never p=8

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bors commented Jan 26, 2024

📌 Commit 907936e has been approved by compiler-errors

It is now in the queue for this repository.

@bors bors removed the S-waiting-on-review Status: Awaiting review from the assignee but also interested parties. label Jan 26, 2024
@bors bors added the S-waiting-on-bors Status: Waiting on bors to run and complete tests. Bors will change the label on completion. label Jan 26, 2024
bors added a commit to rust-lang-ci/rust that referenced this pull request Jan 26, 2024
…mpiler-errors

Rollup of 8 pull requests

Successful merges:

 - rust-lang#118803 (Add the `min_exhaustive_patterns` feature gate)
 - rust-lang#119286 (show linker output even if the linker succeeds)
 - rust-lang#119616 (Add a new `wasm32-wasi-preview2` target)
 - rust-lang#120124 (Split assembly tests for ELF and MachO)
 - rust-lang#120201 (Bump some deps with syn 1.0 dependencies)
 - rust-lang#120204 (Builtin macros effectively have implicit #[collapse_debuginfo(yes)])
 - rust-lang#120322 (Don't manually resolve async closures in `rustc_resolve`)
 - rust-lang#120356 (Fix broken markdown in csky-unknown-linux-gnuabiv2.md)

r? `@ghost`
`@rustbot` modify labels: rollup
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bors commented Jan 26, 2024

⌛ Testing commit 907936e with merge de9022d...

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bors commented Jan 26, 2024

💔 Test failed - checks-actions

@bors bors added S-waiting-on-review Status: Awaiting review from the assignee but also interested parties. and removed S-waiting-on-bors Status: Waiting on bors to run and complete tests. Bors will change the label on completion. labels Jan 26, 2024
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