Commit Graph

3649 Commits

Author SHA1 Message Date
许杰友 Jieyou Xu (Joe) 04caa77a7d
Merge pull request #2366 from rust-lang/tshepang-patch-1 2025-04-30 18:39:22 +08:00
Tshepang Mbambo 1b2f1c30d9
for a more friendly output
Also, these are normal Rust things (crates/packages), so remove the word *normal*.
2025-04-29 23:39:06 +02:00
Tshepang Mbambo 64dd1c3a8c
Merge pull request #2363 from smanilov/patch-1
Update compiler-src.md
2025-04-29 23:01:31 +02:00
Travis Cross 2cc8f1a3a1 Merge PR #2360: Add docs about stabilizing an edition 2025-04-29 19:09:46 +00:00
Boxy 3c3aa7ebb4
Merge pull request #2365 from BoxyUwU/norm_footnotes
Fix footnotes
2025-04-29 19:38:28 +01:00
Boxy 2eae1c6f99 Fix footnotes 2025-04-29 19:35:26 +01:00
lcnr 12be276e9d
Merge pull request #2266 from BoxyUwU/normalization
Introduce a normalization chapter
2025-04-29 20:19:27 +02:00
Boxy 38a5e54ccd Introduce a normalization chapter 2025-04-29 19:08:55 +01:00
Stan Manilov 7700fb5dc8
Update compiler-src.md
Refactor the dependency structure from a nested unordered list to a single-level ordered list.

IMO, this is clearer, but happy to close this PR without merging, if the change is not desired.
2025-04-29 16:39:54 +03:00
Yuki Okushi b5367b8f95
Merge pull request #2361 from ehuss/update-mdbook 2025-04-29 09:12:05 +09:00
Eric Huss fb49fb6ba0 Add documentation on how to stabilize the compiler edition
This adds documentation on how to stabilize the edition in the compiler.
2025-04-28 14:53:36 -07:00
Eric Huss 5df71be99d Update mdbook to 0.4.48
This updates to the latest version of mdbook which has had a variety
of fixes of new features since the last update.

Changelog: https://github.com/rust-lang/mdBook/blob/master/CHANGELOG.md#mdbook-0448
2025-04-28 11:41:17 -07:00
Eric Huss 4ba34d12fb Add documentation on how to migration the edition of the standard library
Based on lessons learned from 2024. There's probably still more details
to say here since it was a ton of work. These are the major points that
I remember.
2025-04-28 11:30:33 -07:00
Eric Huss d0998d33cb Add an example of the example of an edition migration lint
It was observed that some people were missing the `edition20xx` rustdoc
attribute. Although this probably won't solve that problem, I'd still
like to highlight it as something to be aware of.
2025-04-28 11:29:42 -07:00
Tshepang Mbambo f2e5577050
Merge pull request #2358 from rust-lang/rustc-pull
Rustc pull update
2025-04-28 06:25:10 +02:00
The rustc-dev-guide Cronjob Bot 825c56bcaa Merge from rustc 2025-04-28 04:02:54 +00:00
The rustc-dev-guide Cronjob Bot 420aa5f9ea Preparing for merge from rustc 2025-04-28 04:02:47 +00:00
Yuki Okushi 9b18c5f55c
Merge pull request #2351 from rust-lang/rustc-pull 2025-04-27 18:53:00 +09:00
bors e6c1a64cca Auto merge of #140291 - GuillaumeGomez:doctest-2024-stdout, r=notriddle
Correctly display stdout and stderr in case a doctest is failing

Fixes https://github.com/rust-lang/rust/issues/140289.

Since the doctest is actually running itself, we need to handle the output directly inside it.

cc `@fmease`
r? `@notriddle`
2025-04-27 07:43:46 +00:00
bors 80e2e9f163 Auto merge of #139646 - lcnr:default-is-fully-concrete, r=BoxyUwU
check types of const param defaults

fixes #139643 by checking that the type of a const parameter default matches the type of the parameter as long as both types are fully concrete

r? `@BoxyUwU`
2025-04-27 01:59:43 +00:00
Tshepang Mbambo 28684f92ff
Merge pull request #2356 from rust-lang/tshepang-patch-2
replace command that does not work
2025-04-26 15:37:24 +02:00
Tshepang Mbambo e36f9af1cd
replace command that does not work 2025-04-26 15:34:43 +02:00
Tshepang Mbambo fae7588172
Merge pull request #2355 from rust-lang/tshepang-patch-1
copy-paste ease
2025-04-26 15:19:08 +02:00
Tshepang Mbambo 2b4bd30756
copy-paste ease 2025-04-26 15:18:36 +02:00
Tshepang Mbambo e708dad6b0
Merge pull request #2354 from rust-lang/tshepang-fix-code-blocks
use correct code block markers
2025-04-26 15:13:59 +02:00
Tshepang Mbambo 0220b0b8a5 use correct code block markers 2025-04-26 15:09:05 +02:00
Tshepang Mbambo b9fbcd1b13
Merge pull request #2343 from hwhsu1231-fork/fix-prefix-chapter
fix(docs): add newlines between prefix/suffix chapters
2025-04-26 14:47:39 +02:00
Tshepang Mbambo 1376352258
Merge pull request #2345 from rust-lang/extraneous
toolchain version does not need to be specified
2025-04-26 13:42:45 +02:00
bors f0ef8ea058 Auto merge of #140177 - tmandry:compiletest-par, r=jieyouxu
[compiletest] Parallelize test discovery

Certain filesystems are slow to service individual read requests, but can service many in parallel. This change brings down the time to run a single cached test on one of those filesystems from 40s to about 8s.
2025-04-26 02:03:54 +00:00
Tshepang Mbambo cc664309b4
Merge pull request #2353 from rust-lang/tshepang-patch-1
typo
2025-04-25 18:33:15 +02:00
Tshepang Mbambo 55d22e3d8c
typo 2025-04-25 18:32:43 +02:00
bors c22085360c Auto merge of #139756 - Zoxc:out-of-order-dep-graph, r=oli-obk
Allow out of order dep graph node encoding

This allows out of order dep graph node encoding by also encoding the index instead of using the file node order as the index.

`MemEncoder` is also brought back to life and used for encoding.

Both of these are done to enable thread-local encoding of dep graph nodes.

This is based on https://github.com/rust-lang/rust/pull/139636.
2025-04-25 15:38:58 +00:00
bors 25ffc1ef86 Auto merge of #140233 - Zalathar:revert-new-executor, r=jieyouxu
Revert compiletest new-executor, to re-land without download-rustc

Revert <https://github.com/rust-lang/rust/pull/139998> because the original merge triggered download-rustc, which messes with test metrics and prevents us from properly comparing them before/after the change.

The plan is to re-land this PR as-is, combined with a trivial compiler change to avoid download-rustc and get proper test metrics for comparison.

This reverts commit be181dd75c83d72fcc95538e235768bc367b76b9, reversing changes made to 645d0ad2a4f145ae576e442ec5c73c0f8eed829b.

r? ghost
2025-04-25 06:00:11 +00:00
bors b31bdf9282 Auto merge of #139752 - usamoi:macos-used, r=saethlin,madsmtm
set subsections_via_symbols for ld64 helper sections

closes https://github.com/rust-lang/rust/issues/139744
cc `@madsmtm`
2025-04-24 22:59:00 +00:00
bors adf332b0ba Auto merge of #140245 - matthiaskrgr:rollup-e0fwsfv, r=matthiaskrgr
Rollup of 8 pull requests

Successful merges:

 - #139261 (mitigate MSVC alignment issue on x86-32)
 - #140075 (Mention average in midpoint documentations)
 - #140184 (Update doc of cygwin target)
 - #140186 (Rename `compute_x` methods)
 - #140194 (minicore: Have `//@ add-core-stubs` also imply `-Cforce-unwind-tables=yes`)
 - #140195 (triagebot: label minicore changes w/ `A-test-infra-minicore` and ping jieyouxu on changes)
 - #140214 (Remove comment about handling non-global where bounds with corresponding projection)
 - #140228 (Revert overzealous parse recovery for single colons in paths)

r? `@ghost`
`@rustbot` modify labels: rollup
2025-04-24 12:06:16 +00:00
Matthias Krüger a157a488e8
Rollup merge of #140228 - fmease:revert-overzealous-colon-recovery, r=jieyouxu
Revert overzealous parse recovery for single colons in paths

Basically manually reverts #136808, cc ``@chenyukang`` ``@estebank.``

Reopens #129273.
Fixes [after beta backport] #140227.
2025-04-24 11:40:47 +02:00
Matthias Krüger 2121525677
Rollup merge of #140214 - compiler-errors:remove-hack, r=lcnr
Remove comment about handling non-global where bounds with corresponding projection

This comment is no longer relevant since we only assemble rigid projections if no param-env candidates hold.

Also remove a stray comment from the old solver.

r? lcnr
2025-04-24 11:40:46 +02:00
Matthias Krüger 5efe05a732
Rollup merge of #140195 - jieyouxu:minicore-triagebot, r=jieyouxu
triagebot: label minicore changes w/ `A-test-infra-minicore` and ping jieyouxu on changes

Just routine triagebot labelling/mentioning changes.

r? ```@ghost```
2025-04-24 11:40:44 +02:00
Matthias Krüger 3df0e6542b
Rollup merge of #140194 - jieyouxu:minicore-force-unwind-tables, r=bjorn3
minicore: Have `//@ add-core-stubs` also imply `-Cforce-unwind-tables=yes`

To preserve CFI directives in assembly tests, as `//@ add-core-stubs` already imply `-C panic=abort`.

This is a blocker for https://github.com/rust-lang/rust/pull/140037#issuecomment-2816665358.

cc ```@RalfJung```
r? ```@bjorn3```
2025-04-24 11:40:42 +02:00
Matthias Krüger 6668ae14a4
Rollup merge of #140075 - Urgau:midpoint-average, r=tgross35
Mention average in midpoint documentations

Added a mention to "average" in midpoint documentations and as well as some `#[doc(alias = "average")]`[^1].

This is done to improve the discoverability of the function.

[^1]: https://docs.rs/num-integer/latest/num_integer/trait.Average.html#tymethod.average_floor
2025-04-24 11:40:38 +02:00
Matthias Krüger c67c520bc2
Rollup merge of #139261 - RalfJung:msvc-align-mitigation, r=oli-obk
mitigate MSVC alignment issue on x86-32

This implements mitigation for https://github.com/rust-lang/rust/issues/112480 by stopping to emit `align` attributes on loads and function arguments when building for a win32 MSVC target. MSVC is known to not properly align `u64` and similar types, and claiming to LLVM that everything is properly aligned increases the chance that this will cause problems.

Of course, the misalignment is still a bug, but we can't fix that bug, only MSVC can.

Also add an errata note to the platform support page warning users about this known problem.

try-job: `i686-msvc*`
2025-04-24 11:40:35 +02:00
The rustc-dev-guide Cronjob Bot 6310a6f64c Merge from rustc 2025-04-24 04:02:56 +00:00
The rustc-dev-guide Cronjob Bot 4837eb332b Preparing for merge from rustc 2025-04-24 04:02:49 +00:00
bors 0708bec824 Auto merge of #139309 - RalfJung:abi_unsupported_vector_types, r=fee1-dead,traviscross
make abi_unsupported_vector_types a hard error

Fixes https://github.com/rust-lang/rust/issues/116558 by completing the transition; see that issue for context. The lint was introduced with Rust 1.84 and this has been shown in cargo's future breakage reports since Rust 1.85, released 6 weeks ago, and so far we got 0 complaints by users. There's not even a backlink on the tracking issue. We did a [crater run](https://github.com/rust-lang/rust/pull/127731#issuecomment-2286736295) when the lint was originally added and found no breakage. So I don't think we need another crater run now, but I can do one if the team prefers that.

https://github.com/rust-lang/rust/issues/131800 is done, so for most current targets (in particular, all tier 1 and tier 2 targets) we have the information to implement this check (modulo the targets where we don't properly support SIMD vectors yet, see the sub-issues of https://github.com/rust-lang/rust/issues/116558). If a new target gets added in the future, it will default to reject all SIMD vector types until proper information is added, which is the default we want.

This will need approval by for `@rust-lang/lang.` Cc `@workingjubilee` `@veluca93`

try-job: test-various
try-job: armhf-gnu
try-job: dist-i586-gnu-i586-i686-musl
2025-04-24 00:44:40 +00:00
Jieyou Xu dd639a47fe
rustc-dev-guide: document that `//@ add-core-stubs` imply `-Cforce-unwind-tables=yes` 2025-04-23 17:18:20 +08:00
bors 7537d3bba6 Auto merge of #138591 - Kobzol:git-ci, r=Mark-Simulacrum
Refactor git change detection in bootstrap

While working on https://github.com/rust-lang/rust/pull/138395, I finally found the courage to delve into the insides of git path change detection in bootstrap, which is used (amongst other things) to detect if we should rebuilt od download `[llvm|rustc|gcc]`. I found it a bit hard to understand, and given that this code was historically quite fragile, I thought that it would be better to rebuild it from scratch.

The previous approach had a bunch of limitations:
- It separated the computation of "are there local changes?" and "what upstream SHA should we use?" even though these two things are intertwined.
- It used hacks to work around what happens on CI.
- It had special cases for CI scattered throughout the codebase, rather than centralized in one place.
- It wasn't documented enough and didn't have tests for the git behavior.

The current approach should hopefully resolve all of that. I implemented a single entrypoint called `check_path_modifications` (naming bikeshed pending, half of the time I spend on this PR was thinking about names, as it's quite tricky here..) that explicitly receives a mode of operation (in CI or outside CI), and accordingly figures out that upstream SHA that we should use for downloading artifacts and it also figures out if there are any local changes. Users of this function can then use this unified output to implement `download-ci-X` and other functionality. Notably, this change detection no longer uses `git merge-base`, which makes it easier to use and doesn't require setting up remotes.

I also added a bunch of integration tests that literally spawn a git repository on disk and then check that the function can deal with various situations (PR CI, auto/try CI, local builds).

After I built this inner layer, I used it for downloading GCC, LLVM and rustc. The latter two (and especially rustc) were using the `last_modified_commit` function before, but in all cases but one this function was actually only used to check if there are any local changes, which was IMO confusing. The LLVM handling would deserve a bit of refactoring, but that's a larger change that can be done as a follow-up.

I hope that the implementation is now clear and easy to understand, so that in combination with the tests we can have more confidence that it does what we want. I tried to include a lot of documentation in the code, so I won't be repeating the actual implementation details here, if there are any questions, I'll add the answers to the documentation too :)

The new approach explicitly supports three scenarios:
- Running on PR CI, where we have one upstream bors parent commit and one PR merge commit made by GitHub.
- Running on try/auto CI, where we have one upstream bors parent commit and one PR merge commit made by bors.
- Running locally, where we assume that we have at least one upstream bors parent commit in our git history.

I removed the handling of upstreams on CI, as I think that it shouldn't be needed and I considered it to be a hack. However, it's possible that there are other use-cases that I haven't considered, so I want to ask around if people have other situations than the three use-cases described above. If there are other such use-cases, I would like to include them in the new centralized implementation and add them to the git test suite, rather than going back to the old ways :)

In particular, the code before relied on `git merge-base`, but I don't see why we can't just lookup the most recent bors commit and assume that is a merge commit that is also upstream? I might be running into Chesterton's Fence here :)

CC `@pietroalbini` To make sure that this won't break downstream users of Rust's CI.

Best reviewed commit by commit.

Companion PRs:
- For testing beta: https://github.com/rust-lang/rust/pull/138597

r? `@onur-ozkan`

Fixes: https://github.com/rust-lang/rust/issues/101907

try-job: x86_64-gnu-aux
try-job: aarch64-gnu
try-job: dist-x86_64-apple
2025-04-23 03:10:04 +00:00
bors 91efc2c192 Auto merge of #139960 - amandasystems:placeholder-ui-tests, r=lcnr
Add tests for two untested cases of placeholder relations

During work on #130227, I discovered several situations not covered by any previously existing UI test. This commit introudces tests to cover that.

r? lcnr
2025-04-22 11:05:54 +00:00
bors d9ad280a69 Auto merge of #132833 - est31:stabilize_let_chains, r=fee1-dead
Stabilize let chains in the 2024 edition

# Stabilization report

This proposes the stabilization of `let_chains` ([tracking issue], [RFC 2497]) in the [2024 edition] of Rust.

[tracking issue]: https://github.com/rust-lang/rust/issues/53667
[RFC 2497]: https://github.com/rust-lang/rfcs/pull/2497
[2024 edition]: https://doc.rust-lang.org/nightly/edition-guide/rust-2024/index.html

## What is being stabilized

The ability to `&&`-chain `let` statements inside `if` and `while` is being stabilized, allowing intermixture with boolean expressions. The patterns inside the `let` sub-expressions can be irrefutable or refutable.

```Rust
struct FnCall<'a> {
    fn_name: &'a str,
    args: Vec<i32>,
}

fn is_legal_ident(s: &str) -> bool {
    s.chars()
        .all(|c| ('a'..='z').contains(&c) || ('A'..='Z').contains(&c))
}

impl<'a> FnCall<'a> {
    fn parse(s: &'a str) -> Option<Self> {
        if let Some((fn_name, after_name)) = s.split_once("(")
            && !fn_name.is_empty()
            && is_legal_ident(fn_name)
            && let Some((args_str, "")) = after_name.rsplit_once(")")
        {
            let args = args_str
                .split(',')
                .map(|arg| arg.parse())
                .collect::<Result<Vec<_>, _>>();
            args.ok().map(|args| FnCall { fn_name, args })
        } else {
            None
        }
    }
    fn exec(&self) -> Option<i32> {
        let iter = self.args.iter().copied();
        match self.fn_name {
            "sum" => Some(iter.sum()),
            "max" => iter.max(),
            "min" => iter.min(),
            _ => None,
        }
    }
}

fn main() {
    println!("{:?}", FnCall::parse("sum(1,2,3)").unwrap().exec());
    println!("{:?}", FnCall::parse("max(4,5)").unwrap().exec());
}
```

The feature will only be stabilized for the 2024 edition and future editions. Users of past editions will get an error with a hint to update the edition.

closes #53667

## Why 2024 edition?

Rust generally tries to ship new features to all editions. So even the oldest editions receive the newest features. However, sometimes a feature requires a breaking change so much that offering the feature without the breaking change makes no sense. This occurs rarely, but has happened in the 2018 edition already with `async` and `await` syntax. It required an edition boundary in order for `async`/`await` to become keywords, and the entire feature foots on those keywords.

In the instance of let chains, the issue is the drop order of `if let` chains. If we want `if let` chains to be compatible with `if let`, drop order makes it hard for us to [generate correct MIR]. It would be strange to have different behaviour for `if let ... {}` and `if true && let ... {}`. So it's better to [stay consistent with `if let`].

In edition 2024, [drop order changes] have been introduced to make `if let` temporaries be lived more shortly. These changes also affected `if let` chains. These changes make sense even if you don't take the `if let` chains MIR generation problem into account. But if we want to use them as the solution to the MIR generation problem, we need to restrict let chains to edition 2024 and beyond: for let chains, it's not just a change towards more sensible behaviour, but one required for correct function.

[generate correct MIR]: https://github.com/rust-lang/rust/issues/104843
[stay consistent with `if let`]: https://github.com/rust-lang/rust/pull/103293#issuecomment-1293408574
[drop order changes]: https://github.com/rust-lang/rust/issues/124085

## Introduction considerations

As edition 2024 is very new, this stabilization PR only makes it possible to use let chains on 2024 without that feature gate, it doesn't mark that feature gate as stable/removed. I would propose to continue offering the `let_chains` feature (behind a feature gate) for a limited time (maybe 3 months after stabilization?) on older editions to allow nightly users to adopt edition 2024 at their own pace. After that, the feature gate shall be marked as *stabilized*, not removed, and replaced by an error on editions 2021 and below.

## Implementation history

* History from before March 14, 2022 can be found in the [original stabilization PR] that was reverted.
* https://github.com/rust-lang/rust/pull/94927
* https://github.com/rust-lang/rust/pull/94951
* https://github.com/rust-lang/rust/pull/94974
* https://github.com/rust-lang/rust/pull/95008
* https://github.com/rust-lang/rust/pull/97295
* https://github.com/rust-lang/rust/pull/98633
* https://github.com/rust-lang/rust/pull/99731
* https://github.com/rust-lang/rust/pull/102394
* https://github.com/rust-lang/rust/pull/100526
* https://github.com/rust-lang/rust/pull/100538
* https://github.com/rust-lang/rust/pull/102998
* https://github.com/rust-lang/rust/pull/103405
* https://github.com/rust-lang/rust/pull/103293
* https://github.com/rust-lang/rust/pull/107251
* https://github.com/rust-lang/rust/pull/110568
* https://github.com/rust-lang/rust/pull/115677
* https://github.com/rust-lang/rust/pull/117743
* https://github.com/rust-lang/rust/pull/117770
* https://github.com/rust-lang/rust/pull/118191
* https://github.com/rust-lang/rust/pull/119554
* https://github.com/rust-lang/rust/pull/129394
* https://github.com/rust-lang/rust/pull/132828
* https://github.com/rust-lang/reference/pull/1179
* https://github.com/rust-lang/reference/pull/1251
* https://github.com/rust-lang/rustfmt/pull/5910

[original stabilization PR]: https://github.com/rust-lang/rust/pull/94927

## Adoption history

### In the compiler

* History before March 14, 2022 can be found in the [original stabilization PR].
* https://github.com/rust-lang/rust/pull/115983
* https://github.com/rust-lang/rust/pull/116549
* https://github.com/rust-lang/rust/pull/116688

### Outside of the compiler

* https://github.com/rust-lang/rust-clippy/pull/11750
* [rspack](https://github.com/web-infra-dev/rspack)
* [risingwave](https://github.com/risingwavelabs/risingwave)
* [dylint](https://github.com/trailofbits/dylint)
* [convex-backend](https://github.com/get-convex/convex-backend)
* [tikv](https://github.com/tikv/tikv)
* [Daft](https://github.com/Eventual-Inc/Daft)
* [greptimedb](https://github.com/GreptimeTeam/greptimedb)

## Tests

<details>

### Intentional restrictions

[`partially-macro-expanded.rs`](4adafcf40a/tests/ui/rfcs/rfc-2294-if-let-guard/partially-macro-expanded.rs), [`macro-expanded.rs`](4adafcf40a/tests/ui/rfcs/rfc-2294-if-let-guard/macro-expanded.rs): it is possible to use macros to expand to both the pattern and the expression inside a let chain, but not to the entire `let pat = expr` operand.
[`parens.rs`](4adafcf40a/tests/ui/rfcs/rfc-2294-if-let-guard/parens.rs): `if (let pat = expr)` is not allowed in chains
[`ensure-that-let-else-does-not-interact-with-let-chains.rs`](4adafcf40a/tests/ui/rfcs/rfc-2497-if-let-chains/ensure-that-let-else-does-not-interact-with-let-chains.rs): `let...else` doesn't support chaining.

### Overlap with match guards

[`move-guard-if-let-chain.rs`](4adafcf40a/tests/ui/rfcs/rfc-2294-if-let-guard/move-guard-if-let-chain.rs): test for the `use moved value` error working well in match guards. could maybe be extended with let chains that have more than one `let`
[`shadowing.rs`](4adafcf40a/tests/ui/rfcs/rfc-2294-if-let-guard/shadowing.rs): shadowing in if let guards works as expected
[`ast-validate-guards.rs`](4adafcf40a/tests/ui/rfcs/rfc-2497-if-let-chains/ast-validate-guards.rs): let chains in match guards require the match guards feature gate

### Simple cases from the early days

PR #88642 has added some tests with very simple usages of `let else`, mostly as regression tests to early bugs.

[`then-else-blocks.rs`](4adafcf40a/tests/ui/rfcs/rfc-2497-if-let-chains/then-else-blocks.rs)
[`ast-lowering-does-not-wrap-let-chains.rs`](4adafcf40a/tests/ui/rfcs/rfc-2497-if-let-chains/ast-lowering-does-not-wrap-let-chains.rs)
[`issue-90722.rs`](4adafcf40a/tests/ui/rfcs/rfc-2497-if-let-chains/issue-90722.rs)
[`issue-92145.rs`](4adafcf40a/tests/ui/rfcs/rfc-2497-if-let-chains/issue-92145.rs)

### Drop order/MIR scoping tests

[`issue-100276.rs`](4adafcf40a/tests/ui/drop/issue-100276.rs): let expressions on RHS aren't terminating scopes
[`drop_order.rs`](4adafcf40a/tests/ui/drop/drop_order.rs): exhaustive temporary drop order test for various Rust constructs, including let chains
[`scope.rs`](4adafcf40a/tests/ui/rfcs/rfc-2294-if-let-guard/scope.rs): match guard scoping test
[`drop-scope.rs`](4adafcf40a/tests/ui/rfcs/rfc-2294-if-let-guard/drop-scope.rs): another match guard scoping test, ensuring that temporaries in if-let guards live for the arm
[`drop_order_if_let_rescope.rs`](4adafcf40a/tests/ui/drop/drop_order_if_let_rescope.rs): if let rescoping on edition 2024, including chains
[`mir_let_chains_drop_order.rs`](4adafcf40a/tests/ui/mir/mir_let_chains_drop_order.rs): comprehensive drop order test for let chains, distinguishes editions 2021 and 2024.
[`issue-99938.rs`](4adafcf40a/tests/ui/rfcs/rfc-2497-if-let-chains/issue-99938.rs), [`issue-99852.rs`](4adafcf40a/tests/ui/mir/issue-99852.rs) both bad MIR ICEs fixed by #102394

### Linting

[`irrefutable-lets.rs`](4adafcf40a/tests/ui/rfcs/rfc-2497-if-let-chains/irrefutable-lets.rs): trailing and leading irrefutable let patterns get linted for, others don't. The lint is turned off for `else if`.
[`issue-121070-let-range.rs`](4adafcf40a/tests/ui/lint/issue-121070-let-range.rs): regression test for false positive of the unused parens lint, precedence requires the `()`s here

### Parser: intentional restrictions

[`disallowed-positions.rs`](2128d8df0e/tests/ui/rfcs/rfc-2497-if-let-chains/disallowed-positions.rs): `let` in expression context is rejected everywhere except at the top level
[`invalid-let-in-a-valid-let-context.rs`](4adafcf40a/tests/ui/rfcs/rfc-2497-if-let-chains/invalid-let-in-a-valid-let-context.rs): nested `let` is not allowed (let's are no legal expressions just because they are allowed in `if` and `while`).

### Parser: recovery

[`issue-103381.rs`](4adafcf40a/tests/ui/parser/issues/issue-103381.rs): Graceful recovery of incorrect chaining of `if` and `if let`
[`semi-in-let-chain.rs`](4adafcf40a/tests/ui/parser/semi-in-let-chain.rs): Ensure that stray `;`s in let chains give nice errors (`if_chain!` users might be accustomed to `;`s)
[`deli-ident-issue-1.rs`](4adafcf40a/tests/ui/parser/deli-ident-issue-1.rs), [`brace-in-let-chain.rs`](4adafcf40a/tests/ui/parser/brace-in-let-chain.rs): Ensure that stray unclosed `{`s in let chains give nice errors and hints

### Misc

[`conflicting_bindings.rs`](4adafcf40a/tests/ui/pattern/usefulness/conflicting_bindings.rs): the conflicting bindings check also works in let chains. Personally, I'd extend it to chains with multiple let's as well.
[`let-chains-attr.rs`](4adafcf40a/tests/ui/expr/if/attrs/let-chains-attr.rs): attributes work on let chains

### Tangential tests with `#![feature(let_chains)]`

[`if-let.rs`](4adafcf40a/tests/coverage/branch/if-let.rs): MC/DC coverage tests for let chains
[`logical_or_in_conditional.rs`](4adafcf40a/tests/mir-opt/building/logical_or_in_conditional.rs): not really about let chains, more about dropping/scoping behaviour of `||`
[`stringify.rs`](4adafcf40a/tests/ui/macros/stringify.rs): exhaustive test of the `stringify` macro
[`expanded-interpolation.rs`](4adafcf40a/tests/ui/unpretty/expanded-interpolation.rs), [`expanded-exhaustive.rs`](4adafcf40a/tests/ui/unpretty/expanded-exhaustive.rs): Exhaustive test of `-Zunpretty`
[`diverges-not.rs`](4adafcf40a/tests/ui/rfcs/rfc-0000-never_patterns/diverges-not.rs): Never type, mostly tangential to let chains

</details>

## Possible future work

* There is proposals to allow `if let Pat(bindings) = expr {}` to be written as `if expr is Pat(bindings) {}` ([RFC 3573]). `if let` chains are a natural extension of the already existing `if let` syntax, and I'd argue orthogonal towards `is` syntax.
  * https://github.com/rust-lang/lang-team/issues/297
* One could have similar chaining inside `let ... else` statements. There is no proposed RFC for this however, nor is it implemented on nightly.
* Match guards have the `if` keyword as well, but on stable Rust, they don't support `let`. The functionality is available via an unstable feature ([`if_let_guard` tracking issue]). Stabilization of let chains affects this feature in so far as match guards containing let chains now only need the `if_let_guard` feature gate be present instead of also the `let_chains` feature (NOTE: this PR doesn't implement this simplification, it's left for future work).

[RFC 3573]: https://github.com/rust-lang/rfcs/pull/3573
[`if_let_guard` tracking issue]: https://github.com/rust-lang/rust/issues/51114

## Open questions / blockers

- [ ] bad recovery if you don't put a `let` (I don't think this is a blocker): [#117977](https://github.com/rust-lang/rust/issues/117977)
- [x] An instance where a temporary lives shorter than with nested ifs, breaking compilation: [#103476](https://github.com/rust-lang/rust/issues/103476). Personally I don't think this is a blocker either, as it's an edge case. Edit: turns out to not reproduce in edition 2025 any more, due to let rescoping. regression test added in #133093
- [x] One should probably extend the tests for `move-guard-if-let-chain.rs` and `conflicting_bindings.rs` to have chains with multiple let's: done in 133093
- [x] Parsing rejection tests: addressed by https://github.com/rust-lang/rust/pull/132828
- [x] [Style](https://rust-lang.zulipchat.com/#narrow/channel/346005-t-style/topic/let.20chains.20stabilization.20and.20formatting): https://github.com/rust-lang/rust/pull/139456
- [x] https://github.com/rust-lang/rust/issues/86730 explicitly mentions `let_else`. I think we can live with `let pat = expr` not evaluating as `expr` for macro_rules macros, especially given that `let pat = expr` is not a legal expression anywhere except inside `if` and `while`.
- [x] Documentation in the reference: https://github.com/rust-lang/reference/pull/1740
- [x] Add chapter to the Rust 2024 [edition guide]: https://github.com/rust-lang/edition-guide/pull/337
- [x] Resolve open questions on desired drop order.

[original reference PR]: https://github.com/rust-lang/reference/pull/1179
[edition guide]: https://github.com/rust-lang/edition-guide
2025-04-22 07:54:10 +00:00
Manuel Drehwald c4d85f1cc1
Merge pull request #2350 from rust-lang/update-autodiff-build-instr
update build and test instructions
2025-04-22 01:17:18 -04:00
Manuel Drehwald e74f97682c update build and test instructions 2025-04-22 01:16:04 -04:00