Commit Graph

2430 Commits

Author SHA1 Message Date
Guillaume Gomez
93ca0af08c
Rollup merge of #141603 - nnethercote:reduce-P, r=fee1-dead
Reduce `ast::ptr::P` to a typedef of `Box`

As per the MCP at https://github.com/rust-lang/compiler-team/issues/878.

r? `@fee1-dead`
2025-06-06 23:53:16 +02:00
Josh Stone
af2a85bd75 Ensure stack in Parser::parse_ty
This solve a stack overflow found on Fedora s390x when building
`tests/ui/associated-consts/issue-93775.rs`.
2025-06-04 15:21:30 -07:00
Matthias Krüger
0736a03a78
Rollup merge of #141570 - chenyukang:yukang-fix-eq_unspanned, r=workingjubilee
Fix incorrect eq_unspanned in TokenStream

Fixes rust-lang/rust#141522

r? ``@workingjubilee``

should we remove this function?
since it's used in several places, i'd prefer to keep it.
2025-06-04 16:24:07 +02:00
Matthias Krüger
96531418f8
Rollup merge of #141945 - nnethercote:rm-Path-is_ident, r=compiler-errors
Remove `Path::is_ident`.

It checks that a path has a single segment that matches the given symbol, and that there are zero generic arguments. It has a single use.

We also have `impl PartialEq<Symbol> for Path` which does exactly the same thing *except* it doesn't check for zero generic arguments, which seems like an oversight. It has numerous uses.

This commit removes `Path::is_ident`, adds a test for zero generic arguments to `PartialEq<Symbol> for Path`, and changes the single use of `is_ident` to instead use `==`.

r? `@wesleywiser`
2025-06-03 21:53:38 +02:00
Oli Scherer
5fbdfc3e10
Add iter macro
This adds an `iter!` macro that can be used to create movable
generators.

This also adds a yield_expr feature so the `yield` keyword can be used
within iter! macro bodies. This was needed because several unstable
features each need `yield` expressions, so this allows us to stabilize
them separately from any individual feature.

Co-authored-by: Oli Scherer <github35764891676564198441@oli-obk.de>
Co-authored-by: Jieyou Xu <jieyouxu@outlook.com>
Co-authored-by: Travis Cross <tc@traviscross.com>
2025-06-03 10:52:32 -07:00
Nicholas Nethercote
04391045d0 Remove Path::is_ident.
It checks that a path has a single segment that matches the given
symbol, and that there are zero generic arguments. It has a single use.

We also have `impl PartialEq<Symbol> for Path` which does exactly the
same thing *except* it doesn't check for zero generic arguments, which
seems like an oversight. It has numerous uses.

This commit removes `Path::is_ident`, adds a test for zero generic
arguments to `PartialEq<Symbol> for Path`, and changes the single use of
`is_ident` to instead use `==`.
2025-06-03 15:21:33 +10:00
Jubilee
5e139db47b
Rollup merge of #141077 - chenyukang:yukang-fix-140991-comma, r=wesleywiser
Fix the issue of typo of comma in arm parsing

Fixes #140991

I also checked is it a '/', since it's near from ',' from keyboard.
2025-05-30 13:52:25 -07:00
Matthias Krüger
5fc3f26748
Rollup merge of #141004 - matthewjasper:unicode-before-expansion, r=davidtwco
Report text_direction_codepoint_in_literal when parsing

The lint is now reported in code that gets removed/modified/duplicated by macro expansion, and spans are more accurate so we don't get ICEs from trying to split a span in the middle of a character.

This removes support for lint level attributes for `text_direction_codepoint_in_literal` except at the crate level, I don't think that there's an easy way around this when the lint can be reported on code that's removed by `cfg` or that is only in the input of a macro.

Fixes #140281
2025-05-30 07:01:28 +02:00
Jacob Pratt
0ac0285c3f
Rollup merge of #141675 - nnethercote:ItemKind-field-order, r=fee1-dead
Reorder `ast::ItemKind::{Struct,Enum,Union}` fields.

So they match the order of the parts in the source code, e.g.:
```
struct Foo<T, U> { t: T, u: U }
       <-><----> <------------>
       /   |       \
   ident generics  variant_data
```

r? `@fee1-dead`
2025-05-29 04:49:43 +02:00
Trevor Gross
d6b1108cda
Rollup merge of #141670 - chenyukang:yukang-fix-ice-from-contracts, r=nnethercote
Fix ICE in tokenstream with contracts from parser recovery

Fixes rust-lang/rust#140683

After two times of parsing error, the `recover_stmt_` constructs an error ast, then when we expand macors, the invalid tokenstream triggered ICE because of mismatched delims.

Expected `{` and get other tokens is an obvious error message, too much effort on recovery may introduce noise.

r? ```@nnethercote```
2025-05-28 10:28:11 -04:00
Nicholas Nethercote
4c4a40f6df Reorder ast::ItemKind::{Struct,Enum,Union} fields.
So they match the order of the parts in the source code, e.g.:
```
struct Foo<T, U> { t: T, u: U }
       <-><----> <------------>
       /   |       \
   ident generics  variant_data
```
2025-05-28 15:48:45 +10:00
yukang
adcd0bf5c3 Fix ICE in tokenstream with contracts from parser recovery 2025-05-28 09:35:10 +08:00
Matthew Jasper
65bdb31a97 Report text_direction_codepoint_in_literal when parsing
- The lint is now reported in code that gets removed/modified/duplicated
  by macro expansion.
- Spans are more accurate
- Fixes #140281
2025-05-27 15:57:41 +00:00
Folkert de Vries
c7c0194d98
move asm parsing code into rustc_parse 2025-05-27 09:44:10 +02:00
Nicholas Nethercote
991c91fdaa Reduce P<T> to a typedef of Box<T>.
Keep the `P` constructor function for now, to minimize immediate churn.

All the `into_inner` calls are removed, which is nice.
2025-05-27 13:29:24 +10:00
Nicholas Nethercote
0f285e346f Remove the one use of P<[T]>.
A `Vec` is fine, the additional word (vector vs. boxed slice) doesn't
matter here.
2025-05-27 02:54:18 +10:00
yukang
d3347bb32b remove eq_unspanned from TokenStream 2025-05-26 17:02:51 +08:00
yukang
5f8954bc41 Fix the issue of typo of comma in arm parsing 2025-05-16 12:40:04 +02:00
Matthias Krüger
e53b9f8fdd
Rollup merge of #141003 - clubby789:ternary-improve, r=compiler-errors
Improve ternary operator recovery

This
- Improves the span of the error to not point at the next token
- Where possible, we use the span of the condition to further improve the span of the error to include the cond, and suggest a maybe-incorrect fix

Currently this works on free expressions, not let statements; some more refactoring would be needed to pass the span down, which I'm not sure is worth doing.

### Old
![image](https://github.com/user-attachments/assets/5688cefc-e4ef-4135-a5ba-340ce05ae6f3)

### New
![image](https://github.com/user-attachments/assets/154f5380-e0c8-42c7-9bf8-0adb3d0433fa)
2025-05-16 07:19:41 +02:00
Jamie
1267333ef1 Improve ternary operator recovery 2025-05-14 13:32:59 +01:00
Pietro Albini
2ce08ca5d6
update cfg(bootstrap) 2025-05-12 15:33:37 +02:00
Kornel
fc20650c6a
Error message for top-level or-patterns suggesting a solution 2025-05-09 22:16:34 +09:00
Nicholas Nethercote
0984db553d Remove Ident::empty.
All uses have been removed. And it's nonsensical: an identifier by
definition has at least one char.

The commits adds an is-non-empty assertion to `Ident::new` to enforce
this, and converts some `Ident` constructions to use `Ident::new`.
Adding the assertion requires making `Ident::new` and
`Ident::with_dummy_span` non-const, which is no great loss.

The commit amends a couple of places that do path splitting to ensure no
empty identifiers are created.
2025-05-09 13:57:49 +10:00
Guillaume Gomez
32325e1dec
Rollup merge of #140671 - xizheyin:issue-140169, r=petrochenkov
Parser: Recover error from named params while parse_path

Fixes #140169

I added test to the first commit and the second added the code and changes to test.

r? `@petrochenkov`
2025-05-07 18:19:06 +02:00
xizheyin
b922da3586 Use parse_param_general when parsing (T, U)->R in parse_path_segment
Signed-off-by: xizheyin <xizheyin@smail.nju.edu.cn>

Co-authored-by: Vadim Petrochenkov <vadim.petrochenkov@gmail.com>
2025-05-07 22:56:14 +08:00
Stuart Cook
627873a078
Rollup merge of #140035 - fee1-dead-contrib:push-oszwkkvmpkks, r=jieyouxu,wesleywiser
Implement RFC 3503: frontmatters

Tracking issue: #136889

Supercedes #137193. This implements [RFC 3503](https://github.com/rust-lang/rfcs/blob/master/text/3503-frontmatter.md).

This might break rust-analyzer. Will look into how to fix that.

Suggestions welcome for how to improve diagnostics.
2025-05-06 16:28:39 +10:00
Deadbeef
662182637e Implement RFC 3503: frontmatters
Supercedes #137193
2025-05-05 23:10:08 +08:00
Jieyou Xu
eb3a8e5b81
Make attribute safety validation logic more obvious 2025-05-04 21:44:50 +08:00
Urgau
f4e1ec111c Report the unsafe_attr_outside_unsafe lint at the closest node 2025-05-03 16:10:25 +02:00
Matthias Krüger
a477172ced
Rollup merge of #140494 - ehuss:document-restrictions, r=traviscross,SparrowLii
Parser: Document restrictions

I had trouble easily understanding what these various flags do. This is my attempt to try to explain what these do.
2025-04-30 22:36:44 +02:00
Vadim Petrochenkov
6668d13de2 ast: Remove token visiting from AST visitor
It's no longer necessary after the removal of nonterminal tokens in #124141.
2025-04-30 10:36:03 +03:00
Eric Huss
2b92f9fb98 Parser: Document restrictions
I had trouble easily understanding what these various flags do. This is
my attempt to try to explain what these do.
2025-04-29 18:05:45 -07:00
Nicholas Nethercote
880e6f716d Use ThinVec to shrink LazyAttrTokenStreamInner. 2025-04-30 07:12:09 +10:00
Nicholas Nethercote
298c56f4ba Simplify LazyAttrTokenStream.
This commit does the following.
- Changes it from `Lrc<Box<dyn ToAttrTokenStream>>` to
  `Lrc<LazyAttrTokenStreamInner>`.
- Reworks `LazyAttrTokenStreamImpl` as `LazyAttrTokenStreamInner`, which
  is a two-variant enum.
- Removes the `ToAttrTokenStream` trait and the two impls of it.

The recursion limit must be increased in some crates otherwise rustdoc
aborts.
2025-04-30 07:10:56 +10:00
Nicholas Nethercote
28236ab703 Move various token stream things from rustc_parse to rustc_ast.
Specifically: `TokenCursor`, `TokenTreeCursor`,
`LazyAttrTokenStreamImpl`, `FlatToken`, `make_attr_token_stream`,
`ParserRange`, `NodeRange`. `ParserReplacement`, and `NodeReplacement`.
These are all related to token streams, rather than actual parsing.

This will facilitate the simplifications in the next commit.
2025-04-29 12:14:27 +10:00
Matthias Krüger
6f6fa0f23a
Rollup merge of #140272 - Kivooeo:new-fix-four, r=est31
Improve error message for `||` (or) in let chains

**Description**

This PR improves the error message when using `||` in an if let chain expression, addressing #140263.

**Changes**

1. Creates a dedicated error message specifically for `||` usage in let chains
2. Points the primary span directly at the `||` operator
3. Removes confusing secondary notes about "let statements" and unsupported contexts
5. Adds UI tests verifying the new error message and valid cases

**Before**
```rust
error: expected expression, found let statement
 --> src/main.rs:2:8
  |
2 |     if let true = true || false {}
  |        ^^^^^^^^^^^^^^^
  |
  = note: only supported directly in conditions of if and while expressions
note: || operators are not supported in let chain expressions
 --> src/main.rs:2:24
  |
2 |     if let true = true || false {}
  |
```

**After**
```rust
error: `||` operators are not supported in let chain conditions
 --> src/main.rs:2:24
  |
2 |     if let true = true || false {}
  |                        ^^
```

**Implementation details**
1. Added new `OrInLetChain` diagnostic in errors.rs

2. Modified `CondChecker` in expr.rs to prioritize the `||` error

3. Updated fluent message definitions to use clearer wording

**Related issue**
Fixes #140263

cc ```@ehuss``` (issue author)
2025-04-26 07:13:08 +02:00
Kivooeo
f072d30741 resolved conflict 2025-04-25 17:02:59 +05:00
Matthias Krüger
564e5ccb5c
Rollup merge of #140202 - est31:let_chains_feature_compiler, r=lcnr
Make #![feature(let_chains)] bootstrap conditional in compiler/

Let chains have been stabilized recently in #132833, so we can remove the gating from our uses in the compiler (as the compiler uses edition 2024).
2025-04-25 07:50:25 +02:00
Matthias Krüger
f45d2bd8ee
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
León Orell Valerian Liehr
16da97be2f
Revert overzealous parse recovery for single colons 2025-04-24 02:57:10 +02:00
bors
553600e0f5 Auto merge of #140180 - ChrisDenton:rollup-5pvs08u, r=ChrisDenton
Rollup of 7 pull requests

Successful merges:

 - #140142 (Some more graphviz tweaks)
 - #140146 (Update `compiler_builtins` to 0.1.156)
 - #140147 (Clean: rename `open_braces` to `open_delimiters` in lexer and move `make_unclosed_delims_error` into `diagnostics.rs`.)
 - #140160 (Use `is_lang_item` and `as_lang_item` instead of handrolling their logic)
 - #140163 (Validate extension in `PathBuf::add_extension`)
 - #140173 (Ping Mara when touching format_args!() internals.)
 - #140175 (`rc""` more clear error message)

r? `@ghost`
`@rustbot` modify labels: rollup
2025-04-23 15:12:33 +00:00
est31
7493e1cdf6 Make #![feature(let_chains)] bootstrap conditional in compiler/ 2025-04-23 16:40:30 +02:00
Chris Denton
ecb9775438
Rollup merge of #140175 - Kivooeo:new-fix-one, r=compiler-errors
`rc""` more clear error message

here is small fix that provides better error message when user is trying to use `rc""` the same way it was made for `rb""`

example of it's work

```rust
  |
2 |     rc"\n";
  |     ^^ unknown prefix
  |
  = note: prefixed identifiers and literals are reserved since Rust 2021
help: use `cr` for a raw C-string
  |
2 -     rc"\n";
2 +     cr"\n";
  |
```

**related issue**
fixes #140170

cc `@cyrgani` (issue author)
2025-04-23 00:43:08 +00:00
Chris Denton
090f6a9629
Rollup merge of #140147 - xizheyin:issue-138401-1, r=compiler-errors
Clean: rename `open_braces` to `open_delimiters` in lexer and move `make_unclosed_delims_error` into `diagnostics.rs`.

Clean code prepared for resolving #138401. To avoid having too many extraneous changes in one PR, I cleaned up some of the naming and method placement in lexer in this PR.
1. For the make_unclosed_delims_error function defined in mod.rs is only used in lexer, so moved into lexer, which enhances encapsulation.
2. For open_braces in TokenTreeDiagInfo the naming is not canonical, as Brace refers to `{...} ` and this variable can store all kinds of different Delimiters. so I named it open_delimiters.

r? `@chenyukang`
2025-04-23 00:43:06 +00:00
Kivooeo
44b19e5fe7 rc and cr more clear error message 2025-04-23 03:15:43 +05:00
Chris Denton
15f8847a25
Rollup merge of #140144 - nnethercote:fix-140098, r=petrochenkov
Handle another negated literal in `eat_token_lit`.

Extends the change from #139653, which was on expressions, to literals.

Fixes #140098.

r? ``@petrochenkov``
2025-04-22 15:24:08 +00:00
Chris Denton
8089e317b5
Rollup merge of #139921 - Kivooeo:master, r=WaffleLapkin
improve diagnostic for raw pointer field access with ->

This PR enhances the error messages emitted by the Rust compiler when users attempt to use the `->` operator for field access on raw pointers or when dereferencing is needed. The changes aim to provide clearer guidance, by suggesting the correct use of the `.` operator and explicit dereferencing.

**Before:**
```
help: `xs` is a raw pointer; try dereferencing it
   |
LL |         (*xs)->count += 1;
   |         ++  +
```

**Now:**
```
help: use `.` on a dereferenced raw pointer instead
   |
LL -         xs->count += 1;
LL +         (*xs).count += 1;
   |
```

I added extra clarification in the message. Since this error occurs in the parser, we can't be certain that the type is a raw pointer. That's why the message includes only a small note in brackets. (In contrast, the message above is emitted in HIR, where we *can* check whether it's a raw pointer.)

**Before:**
```
  --> main.rs:11:11
   |
11 |         xs->count += 1;
   |           ^^
   |
   = help: the . operator will dereference the value if needed
```
**After:**
```
--> main.rs:11:11
   |
11 |         xs->count += 1;
   |           ^^
   |
   = help: the `.` operator will automatically dereference the value, except if the value is a raw pointer
```
2025-04-22 15:24:05 +00:00
bors
8bf5a8d12f 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
xizheyin
dce5d99ce8 Rename open_brace to open_delimiters
Signed-off-by: xizheyin <xizheyin@smail.nju.edu.cn>
2025-04-22 14:37:26 +08:00
xizheyin
e827b17ddb Move make_unclosed_delims_error to lexer/diagonostics.rs
Signed-off-by: xizheyin <xizheyin@smail.nju.edu.cn>
2025-04-22 14:37:26 +08:00