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Author SHA1 Message Date
Joshua Nelson
31e39446ec Stabilize #![feature(label_break_value)] 
# Stabilization proposal

The feature was implemented in https://github.com/rust-lang/rust/pull/50045 by est31 and has been in nightly since 2018-05-16 (over 4 years now).
There are [no open issues][issue-label] other than the tracking issue. There is a strong consensus that `break` is the right keyword and we should not use `return`.

There have been several concerns raised about this feature on the tracking issue (other than the one about tests, which has been fixed, and an interaction with try blocks, which has been fixed).
1. nrc's original comment about cost-benefit analysis: https://github.com/rust-lang/rust/issues/48594#issuecomment-422235234
2. joshtriplett's comments about seeing use cases: https://github.com/rust-lang/rust/issues/48594#issuecomment-422281176
3. withoutboats's comments that Rust does not need more control flow constructs: https://github.com/rust-lang/rust/issues/48594#issuecomment-450050630

Many different examples of code that's simpler using this feature have been provided:
- A lexer by rpjohnst which must repeat code without label-break-value: https://github.com/rust-lang/rust/issues/48594#issuecomment-422502014
- A snippet by SergioBenitez which avoids using a new function and adding several new return points to a function: https://github.com/rust-lang/rust/issues/48594#issuecomment-427628251. This particular case would also work if `try` blocks were stabilized (at the cost of making the code harder to optimize).
- Several examples by JohnBSmith: https://github.com/rust-lang/rust/issues/48594#issuecomment-434651395
- Several examples by Centril: https://github.com/rust-lang/rust/issues/48594#issuecomment-440154733
- An example by petrochenkov where this is used in the compiler itself to avoid duplicating error checking code: https://github.com/rust-lang/rust/issues/48594#issuecomment-443557569
- Amanieu recently provided another example related to complex conditions, where try blocks would not have helped: https://github.com/rust-lang/rust/issues/48594#issuecomment-1184213006

Additionally, petrochenkov notes that this is strictly more powerful than labelled loops due to macros which accidentally exit a loop instead of being consumed by the macro matchers: https://github.com/rust-lang/rust/issues/48594#issuecomment-450246249

nrc later resolved their concern, mostly because of the aforementioned macro problems.
joshtriplett suggested that macros could be able to generate IR directly
(https://github.com/rust-lang/rust/issues/48594#issuecomment-451685983) but there are no open RFCs,
and the design space seems rather speculative.

joshtriplett later resolved his concerns, due to a symmetry between this feature and existing labelled break: https://github.com/rust-lang/rust/issues/48594#issuecomment-632960804

withoutboats has regrettably left the language team.

joshtriplett later posted that the lang team would consider starting an FCP given a stabilization report: https://github.com/rust-lang/rust/issues/48594#issuecomment-1111269353

[issue-label]: https://github.com/rust-lang/rust/issues?q=is%3Aissue+is%3Aopen+label%3AF-label_break_value+

 ## Report

+ Feature gate:
    - d695a497bb/src/test/ui/feature-gates/feature-gate-label_break_value.rs
+ Diagnostics:
    - 6b2d3d5f3c/compiler/rustc_parse/src/parser/diagnostics.rs (L2629)
    - f65bf0b2bb/compiler/rustc_resolve/src/diagnostics.rs (L749)
    - f65bf0b2bb/compiler/rustc_resolve/src/diagnostics.rs (L1001)
    - 111df9e6ed/compiler/rustc_passes/src/loops.rs (L254)
    - d695a497bb/compiler/rustc_parse/src/parser/expr.rs (L2079)
    - d695a497bb/compiler/rustc_parse/src/parser/expr.rs (L1569)
+ Tests:
    - https://github.com/rust-lang/rust/blob/master/src/test/ui/label/label_break_value_continue.rs
    - https://github.com/rust-lang/rust/blob/master/src/test/ui/label/label_break_value_unlabeled_break.rs
    - https://github.com/rust-lang/rust/blob/master/src/test/ui/label/label_break_value_illegal_uses.rs
    - https://github.com/rust-lang/rust/blob/master/src/test/ui/lint/unused_labels.rs
    - https://github.com/rust-lang/rust/blob/master/src/test/ui/run-pass/for-loop-while/label_break_value.rs

 ## Interactions with other features

Labels follow the hygiene of local variables.

label-break-value is permitted within `try` blocks:
```rust
let _: Result<(), ()> = try {
    'foo: {
        Err(())?;
        break 'foo;
    }
};
```

label-break-value is disallowed within closures, generators, and async blocks:
```rust
'a: {
    || break 'a
    //~^ ERROR use of unreachable label `'a`
    //~| ERROR `break` inside of a closure
}
```

label-break-value is disallowed on [_BlockExpression_]; it can only occur as a [_LoopExpression_]:
```rust
fn labeled_match() {
    match false 'b: { //~ ERROR block label not supported here
        _ => {}
    }
}

macro_rules! m {
    ($b:block) => {
        'lab: $b; //~ ERROR cannot use a `block` macro fragment here
        unsafe $b; //~ ERROR cannot use a `block` macro fragment here
        |x: u8| -> () $b; //~ ERROR cannot use a `block` macro fragment here
    }
}

fn foo() {
    m!({});
}
```

[_BlockExpression_]: https://doc.rust-lang.org/nightly/reference/expressions/block-expr.html
[_LoopExpression_]: https://doc.rust-lang.org/nightly/reference/expressions/loop-expr.html
 2022-08-23 21:14:12 -05:00
Xiretza
7f3a6fd7f6 Replace #[lint/warning/error] with #[diag] 2022-08-21 09:17:43 +02:00
bors
dd01122b5c Auto merge of #100564 - nnethercote:box-ast-MacCall, r=spastorino 
Box the `MacCall` in various types.

r? `@spastorino`
 2022-08-20 10:26:54 +00:00
Matthias Krüger
af89769c82
Rollup merge of #100750 - akabinds:akabinds/improved-invalid-function-qual-error, r=davidtwco 
improved diagnostic for function defined with `def`, `fun`, `func`, or `function` instead of `fn`

Closes #99751
 2022-08-20 07:09:05 +02:00
Matthias Krüger
eacbe5437e
Rollup merge of #100667 - Xiretza:diag-structs-parser-ivd, r=davidtwco 
Migrate "invalid variable declaration" errors to SessionDiagnostic

After seeing the great blog post on Inside Rust, I decided to try my hand at this. Just one diagnostic for now to get used to the workflow and to check if this is the way to do it or if there are any problems.
 2022-08-20 07:09:01 +02:00
akabinds
1b54ad0585 added improved diagnostic for a function defined with an invalid qualifier 2022-08-18 16:14:04 -05:00
Matthias Krüger
5548e585c1
Rollup merge of #100670 - Xiretza:parser-stmt-force-collect-docs, r=davidtwco 
Fix documentation of rustc_parse::parser::Parser::parse_stmt_without_recovery

Something seems to have gotten out of sync during the creation of #81177, where both the argument and comment were introduced.
 2022-08-18 05:10:49 +02:00
Xiretza
e8499cfadc Migrate "invalid variable declaration" errors to SessionDiagnostic 2022-08-17 19:08:37 +02:00
Matthias Krüger
d5dca26a94
Rollup merge of #100018 - nnethercote:clean-up-LitKind, r=petrochenkov 
Clean up `LitKind`

r? ``@petrochenkov``
 2022-08-17 12:32:49 +02:00
Xiretza
d3bf103d1b Fix documentation of rustc_parse::parser::Parser::parse_stmt_without_recovery 
Something seems to have gotten out of sync during the creation of #81177,
where both the argument and comment were introduced.
 2022-08-17 11:18:48 +02:00
Nicholas Nethercote
eafd0dfd05 Box the MacCall in various types. 2022-08-17 08:10:56 +10:00
Nicholas Nethercote
5d3cc1713a Rename some things related to literals. 
- Rename `ast::Lit::token` as `ast::Lit::token_lit`, because its type is
  `token::Lit`, which is not a token. (This has been confusing me for a
  long time.)
  reasonable because we have an `ast::token::Lit` inside an `ast::Lit`.
- Rename `LitKind::{from,to}_lit_token` as
  `LitKind::{from,to}_token_lit`, to match the above change and
  `token::Lit`.
 2022-08-16 13:41:34 +10:00
Nicholas Nethercote
9619a2e3a3 Avoid unnecessary cloning in Parser::get_ident_from_generic_arg. 2022-08-16 12:14:52 +10:00
Nicholas Nethercote
3e04fed6fa Remove {ast,hir}::WhereEqPredicate::id. 
These fields are unused.
 2022-08-16 12:13:23 +10:00
Matthias Krüger
e14d12cb66
Rollup merge of #100559 - nnethercote:parser-simplifications, r=compiler-errors 
Parser simplifications

Best reviewed one commit at a time.

r? ``@compiler-errors``
 2022-08-15 20:11:38 +02:00
Matthias Krüger
e369ec871e
Rollup merge of #100458 - compiler-errors:fn-argument-span, r=estebank 
Adjust span of fn argument declaration

Span of a fn argument declaration goes from:

```
fn foo(i : i32 , ...)
       ^^^^^^^^
```

to:

```
fn foo(i : i32 , ...)
       ^^^^^^^
```

That is, we don't include the extra spacing up to the trailing comma, which I think is more correct.

cc https://github.com/rust-lang/rust/pull/99646#discussion_r944568074
r? ``@estebank``

---

The two tests that had dramatic changes in their rendering I think actually are improved, though they are kinda poor spans both before and after the changes. 🤷 Thoughts?
 2022-08-15 20:11:35 +02:00
Matthias Krüger
fece51174b
Rollup merge of #100566 - TaKO8Ki:use-create-snapshot-for-diagnostic, r=cjgillot 
Use `create_snapshot_for_diagnostic` instead of `clone` for `Parser`

follow-up to #98020
 2022-08-15 10:28:14 +02:00
Matthias Krüger
748925bf1b
Rollup merge of #100534 - Rageking8:Rageking8-refactor1, r=compiler-errors 
Make code slightly more uniform
 2022-08-15 10:28:13 +02:00
Takayuki Maeda
84f0d5e460 use create_snapshot_for_diagnostic instead of clone for Parser 2022-08-15 16:42:58 +09:00
Nicholas Nethercote
2ef0479568 Simplify attribute handling in parse_bottom_expr. 
`Parser::parse_bottom_expr` currently constructs an empty `attrs` and
then passes it to a large number of other functions. This makes the code
harder to read than it should be, because it's not clear that many
`attrs` arguments are always empty.

This commit removes `attrs` and the passing, simplifying a lot of
functions. The commit also renames `Parser::mk_expr` (which takes an
`attrs` argument) as `mk_expr_with_attrs`, and introduces a new
`mk_expr` which creates an expression with no attributes, which is the
more common case.
 2022-08-15 13:29:28 +10:00
Nicholas Nethercote
1e8497351d Streamline parse_path_start_expr. 
Let-chaining avoids some code duplication.
 2022-08-15 09:51:11 +10:00
Matthias Krüger
13b8b6ede0
Rollup merge of #100253 - obeis:issue-100197, r=cjgillot 
Recover from mutable variable declaration where `mut` is placed before `let`

Closes #100197
 2022-08-14 20:16:00 +02:00
Rageking8
44f878d75f
Make code slightly more uniform 2022-08-14 22:17:49 +08:00
Dylan DPC
7473484d52
Rollup merge of #100115 - obeis:issue-99910, r=cjgillot 
Suggest removing `let` if `const let` or `let const` is used

Closes #99910
 2022-08-14 17:09:15 +05:30
Michael Goulet
86e1d1e28f
Rollup merge of #100446 - TaKO8Ki:suggest-removing-semicolon-after-impl-trait-items, r=compiler-errors 
Suggest removing a semicolon after impl/trait items

fixes #99822
 2022-08-13 21:06:51 -07:00
Michael Goulet
2af344595a
Rollup merge of #99646 - compiler-errors:arg-mismatch-single-arg-label, r=estebank 
Only point out a single function parameter if we have a single arg incompatibility

Fixes #99635
 2022-08-13 21:06:46 -07:00
Michael Goulet
29f905bfaf
Rollup merge of #100475 - chenyukang:fix-100461, r=fee1-dead 
Give a helpful diagnostic when the next struct field has an attribute

Fixes #100461
 2022-08-13 14:10:12 -07:00
Takayuki Maeda
d47df26784 use span_suggestion instead of span_suggestion_verbose 2022-08-13 22:10:54 +09:00
yukang
52a15180d2 give a helpful diagnostic even when the next struct field has an attribute 2022-08-13 12:50:53 +08:00
Michael Goulet
9b0edd099d Adjust span of fn arguments 2022-08-12 15:21:39 +00:00
Michael Goulet
237cbe91a8 Adjust span of closure param 2022-08-12 15:18:40 +00:00
Dylan DPC
9914c96f06
Rollup merge of #100396 - chenyukang:fix-100394, r=petrochenkov 
Suggest const and static for global variable

Fixing #100394
 2022-08-12 20:39:16 +05:30
Takayuki Maeda
48c0341a70 suggest removing a semicolon after impl/trait items 2022-08-12 18:11:01 +09:00
Matthias Krüger
6ae0414122
Rollup merge of #100350 - jhpratt:stringify-vis, r=cjgillot 
Stringify non-shorthand visibility correctly

This makes `stringify!(pub(in crate))` evaluate to `pub(in crate)` rather than `pub(crate)`, matching the behavior before the `crate` shorthand was removed. Further, this changes `stringify!(pub(in super))` to evaluate to `pub(in super)` rather than the current `pub(super)`. If the latter is not desired (it is _technically_ breaking), it can be undone.

Fixes #99981

`@rustbot` label +C-bug +regression-from-stable-to-beta +T-compiler
 2022-08-11 22:53:06 +02:00
Dylan DPC
b5f5bdce87
Rollup merge of #100351 - compiler-errors:diagnostic-convention, r=fee1-dead 
Use `&mut Diagnostic` instead of `&mut DiagnosticBuilder` unless needed

This seems to be the established convention (02ff9e0) when `DiagnosticBuilder` was first added. I am guilty of introducing some of these.
 2022-08-11 22:47:03 +05:30
chenyukang
98518c2379 suggest const or static for global variable 2022-08-11 23:15:39 +08:00
Camille GILLOT
9701845287 Do not consider method call receiver as an argument in AST. 2022-08-10 18:34:54 +02:00
Michael Goulet
a2b6744af0 Use &mut Diagnostic instead of &mut DiagnosticBuilder unless needed 2022-08-10 03:45:42 +00:00
Jacob Pratt
be5672ecb2
Stringify non-shorthand visibility correctly 2022-08-09 23:31:45 -04:00
Takayuki Maeda
6d85bb9535 suggest a missing semicolon before an array 2022-08-10 02:29:28 +09:00
Obei Sideg
ea2df3a798 Recover from mutable variable declaration where mut is placed before let 2022-08-09 00:55:37 +03:00
Matthias Krüger
18ddb41184
Rollup merge of #100167 - chenyukang:require-suggestion, r=estebank 
Recover `require`, `include` instead of `use` in item

Fix #100140
 2022-08-06 16:15:59 +02:00
Dylan DPC
e7ed8443ea
Rollup merge of #100168 - WaffleLapkin:improve_diagnostics_for_missing_type_in_a_const_item, r=compiler-errors 
Improve diagnostics for `const a: = expr;`

Adds a suggestion to write a type when there is a colon, but the type is not present.
I've also shrunk spans a little, so the suggestions are a little nicer.

Resolves #100146

r? `@compiler-errors`
 2022-08-05 21:54:37 +05:30
Maybe Waffle
743ad07c4b Improve diagnostics for const a: = expr; 2022-08-05 16:19:28 +04:00
yukang
2b15fc6d9a recover require,include instead of use in item 2022-08-05 19:20:03 +08:00
Matthias Krüger
f6ea143f93
Rollup merge of #98796 - compiler-errors:no-semi-if-comma, r=estebank 
Do not exclusively suggest `;` when `,` is also a choice

Fixes #96791
 2022-08-04 22:24:59 +02:00
Obei Sideg
accb8e34c5 Suggest removing let if let const is used 2022-08-04 01:23:14 +03:00
Matthias Krüger
9c18fdc71f
Rollup merge of #99786 - obeis:issue-99625, r=compiler-errors 
Recover from C++ style `enum struct`

Closes #99625
 2022-08-03 22:29:29 +02:00
Obei Sideg
2af92bbf2e Suggest removing let if const let is used 2022-08-03 18:43:29 +03:00
Matthias Krüger
beb4cdddde
Rollup merge of #100011 - compiler-errors:let-chain-restriction, r=fee1-dead 
Use Parser's `restrictions` instead of `let_expr_allowed`

This also means that the `ALLOW_LET` flag is reset properly for subexpressions, so we can properly deny things like `a && (b && let c = d)`. Also the parser is a tiny bit smaller now.

It doesn't reject _all_ bad `let` expr usages, just a bit more.

cc `@c410-f3r`
 2022-08-02 07:30:44 +02:00