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Stabilize #![feature(label_break_value)]

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# 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
This commit is contained in:
Joshua Nelson 2022-07-14 08:30:38 -05:00
parent 4b695f7c4e
commit 31e39446ec
39 changed files with 61 additions and 108 deletions
Show Stats Download Patch File Download Diff File Expand all files Collapse all files

2
compiler/rustc_ast/src/lib.rs
View File

@ -13,7 +13,7 @@
#![feature(const_default_impls)]
#![feature(const_trait_impl)]
#![feature(if_let_guard)]
#![feature(label_break_value)]
#![cfg_attr(bootstrap, feature(label_break_value))]
#![feature(min_specialization)]
#![feature(negative_impls)]
#![feature(slice_internals)]

9
compiler/rustc_ast_passes/src/feature_gate.rs
View File

@ -647,14 +647,6 @@ impl<'a> Visitor<'a> for PostExpansionVisitor<'a> {
ast::ExprKind::TryBlock(_) => {
gate_feature_post!(&self, try_blocks, e.span, "`try` expression is experimental");
}
ast::ExprKind::Block(_, Some(label)) => {
gate_feature_post!(
&self,
label_break_value,
label.ident.span,
"labels on blocks are unstable"
);
}
_ => {}
}
visit::walk_expr(self, e)
@ -823,7 +815,6 @@ pub fn check_crate(krate: &ast::Crate, sess: &Session) {
gate_all!(box_patterns, "box pattern syntax is experimental");
gate_all!(exclusive_range_pattern, "exclusive range pattern syntax is experimental");
gate_all!(try_blocks, "`try` blocks are unstable");
gate_all!(label_break_value, "labels on blocks are unstable");
gate_all!(box_syntax, "box expression syntax is experimental; you can call `Box::new` instead");
gate_all!(type_ascription, "type ascription is experimental");

3
compiler/rustc_error_codes/src/error_codes/E0695.md
View File

@ -3,7 +3,6 @@ A `break` statement without a label appeared inside a labeled block.
Erroneous code example:
```compile_fail,E0695
# #![feature(label_break_value)]
loop {
'a: {
break;
@ -14,7 +13,6 @@ loop {
Make sure to always label the `break`:
```
# #![feature(label_break_value)]
'l: loop {
'a: {
break 'l;
@ -25,7 +23,6 @@ Make sure to always label the `break`:
Or if you want to `break` the labeled block:
```
# #![feature(label_break_value)]
loop {
'a: {
break 'a;

2
compiler/rustc_feature/src/accepted.rs
View File

@ -186,6 +186,8 @@ declare_features! (
/// Allows some increased flexibility in the name resolution rules,
/// especially around globs and shadowing (RFC 1560).
(accepted, item_like_imports, "1.15.0", Some(35120), None),
/// Allows `'a: { break 'a; }`.
(accepted, label_break_value, "1.65.0", Some(48594), None),
/// Allows `if/while p && let q = r && ...` chains.
(accepted, let_chains, "1.64.0", Some(53667), None),
/// Allows `break {expr}` with a value inside `loop`s.

2
compiler/rustc_feature/src/active.rs
View File

@ -420,8 +420,6 @@ declare_features! (
(active, intra_doc_pointers, "1.51.0", Some(80896), None),
/// Allows `#[instruction_set(_)]` attribute
(active, isa_attribute, "1.48.0", Some(74727), None),
/// Allows `'a: { break 'a; }`.
(active, label_break_value, "1.28.0", Some(48594), None),
// Allows setting the threshold for the `large_assignments` lint.
(active, large_assignments, "1.52.0", Some(83518), None),
/// Allows `let...else` statements.

2
compiler/rustc_infer/src/lib.rs
View File

@ -17,7 +17,7 @@
#![feature(box_patterns)]
#![feature(control_flow_enum)]
#![feature(extend_one)]
#![feature(label_break_value)]
#![cfg_attr(bootstrap, feature(label_break_value))]
#![feature(let_else)]
#![feature(min_specialization)]
#![feature(never_type)]

4
compiler/rustc_parse/src/parser/expr.rs
View File

@ -2075,10 +2075,6 @@ impl<'a> Parser<'a> {
}
}
if let Some(label) = opt_label {
self.sess.gated_spans.gate(sym::label_break_value, label.ident.span);
}
if self.token.is_whole_block() {
self.struct_span_err(self.token.span, "cannot use a `block` macro fragment here")
.span_label(lo.to(self.token.span), "the `block` fragment is within this context")

2
compiler/rustc_trait_selection/src/lib.rs
View File

@ -16,7 +16,7 @@
#![feature(control_flow_enum)]
#![feature(drain_filter)]
#![feature(hash_drain_filter)]
#![feature(label_break_value)]
#![cfg_attr(bootstrap, feature(label_break_value))]
#![feature(let_else)]
#![feature(if_let_guard)]
#![feature(never_type)]

2
compiler/rustc_typeck/src/lib.rs
View File

@ -64,7 +64,7 @@ This API is completely unstable and subject to change.
#![feature(if_let_guard)]
#![feature(is_sorted)]
#![feature(iter_intersperse)]
#![feature(label_break_value)]
#![cfg_attr(bootstrap, feature(label_break_value))]
#![feature(let_else)]
#![feature(min_specialization)]
#![feature(never_type)]

2
library/std/src/lib.rs
View File

@ -252,7 +252,7 @@
#![feature(dropck_eyepatch)]
#![feature(exhaustive_patterns)]
#![feature(intra_doc_pointers)]
#![feature(label_break_value)]
#![cfg_attr(bootstrap, feature(label_break_value))]
#![feature(lang_items)]
#![feature(let_else)]
#![feature(linkage)]

5
src/test/ui/feature-gates/feature-gate-label_break_value.rs
View File

@ -1,5 +0,0 @@
pub fn main() {
'a: { //~ ERROR labels on blocks are unstable
break 'a;
}
}

12
src/test/ui/feature-gates/feature-gate-label_break_value.stderr
View File

@ -1,12 +0,0 @@
error[E0658]: labels on blocks are unstable
--> $DIR/feature-gate-label_break_value.rs:2:5
|
LL | 'a: {
| ^^
|
= note: see issue #48594 <https://github.com/rust-lang/rust/issues/48594> for more information
= help: add `#![feature(label_break_value)]` to the crate attributes to enable
error: aborting due to previous error
For more information about this error, try `rustc --explain E0658`.

1
src/test/ui/for-loop-while/label_break_value.rs
View File

@ -1,7 +1,6 @@
// run-pass
#![allow(dead_code)]
#![allow(unused_assignments)]
#![feature(label_break_value)]
// Test control flow to follow label_break_value semantics
fn label_break(a: bool, b: bool) -> u32 {

1
src/test/ui/for-loop-while/label_break_value_invalid.rs
View File

@ -1,5 +1,4 @@
#![crate_type = "lib"]
#![feature(label_break_value)]
fn lbv_macro_test_hygiene_respected() {
macro_rules! mac2 {

6
src/test/ui/for-loop-while/label_break_value_invalid.stderr
View File

@ -1,5 +1,5 @@
error[E0426]: use of undeclared label `'a`
--> $DIR/label_break_value_invalid.rs:7:19
--> $DIR/label_break_value_invalid.rs:6:19
|
LL | break 'a $val;
| ^^ undeclared label `'a`
@ -10,7 +10,7 @@ LL | mac2!(2);
= note: this error originates in the macro `mac2` (in Nightly builds, run with -Z macro-backtrace for more info)
error[E0426]: use of undeclared label `'a`
--> $DIR/label_break_value_invalid.rs:29:19
--> $DIR/label_break_value_invalid.rs:28:19
|
LL | let x: u8 = mac3!('b: {
| -- a label with a similar name is reachable
@ -22,7 +22,7 @@ LL | break 'a 3;
| help: try using similarly named label: `'b`
error[E0426]: use of undeclared label `'a`
--> $DIR/label_break_value_invalid.rs:34:29
--> $DIR/label_break_value_invalid.rs:33:29
|
LL | let x: u8 = mac3!(break 'a 4);
| ^^ undeclared label `'a`

2
src/test/ui/issues/issue-62480.rs
View File

@ -1,5 +1,3 @@
#![feature(label_break_value)]
fn main() {
// This used to ICE during liveness check because `target_id` passed to
// `propagate_through_expr` would be the closure and not the `loop`, which wouldn't be found in

4
src/test/ui/issues/issue-62480.stderr
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@ -1,5 +1,5 @@
error[E0767]: use of unreachable label `'a`
--> $DIR/issue-62480.rs:8:18
--> $DIR/issue-62480.rs:6:18
|
LL | 'a: {
| -- unreachable label defined here
@ -9,7 +9,7 @@ LL | || break 'a
= note: labels are unreachable through functions, closures, async blocks and modules
error[E0267]: `break` inside of a closure
--> $DIR/issue-62480.rs:8:12
--> $DIR/issue-62480.rs:6:12
|
LL | || break 'a
| -- ^^^^^^^^ cannot `break` inside of a closure

1
src/test/ui/label/label_break_value_continue.rs
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@ -1,4 +1,3 @@
#![feature(label_break_value)]
#![allow(unused_labels)]
// Simple continue pointing to an unlabeled break should yield in an error

6
src/test/ui/label/label_break_value_continue.stderr
View File

@ -1,11 +1,11 @@
error[E0695]: unlabeled `continue` inside of a labeled block
--> $DIR/label_break_value_continue.rs:7:9
--> $DIR/label_break_value_continue.rs:6:9
|
LL | continue;
| ^^^^^^^^ `continue` statements that would diverge to or through a labeled block need to bear a label
error[E0696]: `continue` pointing to a labeled block
--> $DIR/label_break_value_continue.rs:14:9
--> $DIR/label_break_value_continue.rs:13:9
|
LL | / 'b: {
LL | | continue 'b;
@ -14,7 +14,7 @@ LL | | }
| |_____- labeled block the `continue` points to
error[E0695]: unlabeled `continue` inside of a labeled block
--> $DIR/label_break_value_continue.rs:22:13
--> $DIR/label_break_value_continue.rs:21:13
|
LL | continue;
| ^^^^^^^^ `continue` statements that would diverge to or through a labeled block need to bear a label

9
src/test/ui/label/label_break_value_desugared_break.rs
View File

@ -1,5 +1,5 @@
// compile-flags: --edition 2018
#![feature(label_break_value, try_blocks)]
#![feature(try_blocks)]
// run-pass
fn main() {
@ -9,4 +9,11 @@ fn main() {
break 'foo;
}
};
'foo: {
let _: Result<(), ()> = try {
Err(())?;
break 'foo;
};
}
}

1
src/test/ui/label/label_break_value_illegal_uses.fixed
View File

@ -1,5 +1,4 @@
// run-rustfix
#![feature(label_break_value)]
// These are forbidden occurrences of label-break-value

1
src/test/ui/label/label_break_value_illegal_uses.rs
View File

@ -1,5 +1,4 @@
// run-rustfix
#![feature(label_break_value)]
// These are forbidden occurrences of label-break-value

8
src/test/ui/label/label_break_value_illegal_uses.stderr
View File

@ -1,23 +1,23 @@
error: block label not supported here
--> $DIR/label_break_value_illegal_uses.rs:8:12
--> $DIR/label_break_value_illegal_uses.rs:7:12
|
LL | unsafe 'b: {}
| ^^^ not supported here
error: block label not supported here
--> $DIR/label_break_value_illegal_uses.rs:12:13
--> $DIR/label_break_value_illegal_uses.rs:11:13
|
LL | if true 'b: {}
| ^^^ not supported here
error: block label not supported here
--> $DIR/label_break_value_illegal_uses.rs:16:21
--> $DIR/label_break_value_illegal_uses.rs:15:21
|
LL | if true {} else 'b: {}
| ^^^ not supported here
error: block label not supported here
--> $DIR/label_break_value_illegal_uses.rs:20:17
--> $DIR/label_break_value_illegal_uses.rs:19:17
|
LL | match false 'b: {
| ^^^ not supported here

1
src/test/ui/label/label_break_value_unlabeled_break.rs
View File

@ -1,4 +1,3 @@
#![feature(label_break_value)]
#![allow(unused_labels)]
// Simple unlabeled break should yield in an error

4
src/test/ui/label/label_break_value_unlabeled_break.stderr
View File

@ -1,11 +1,11 @@
error[E0695]: unlabeled `break` inside of a labeled block
--> $DIR/label_break_value_unlabeled_break.rs:7:9
--> $DIR/label_break_value_unlabeled_break.rs:6:9
|
LL | break;
| ^^^^^ `break` statements that would diverge to or through a labeled block need to bear a label
error[E0695]: unlabeled `break` inside of a labeled block
--> $DIR/label_break_value_unlabeled_break.rs:15:13
--> $DIR/label_break_value_unlabeled_break.rs:14:13
|
LL | break;
| ^^^^^ `break` statements that would diverge to or through a labeled block need to bear a label

1
src/test/ui/lint/unused_labels.rs
View File

@ -4,7 +4,6 @@
// check-pass
#![feature(label_break_value)]
#![warn(unused_labels)]
fn main() {

20
src/test/ui/lint/unused_labels.stderr
View File

@ -1,5 +1,5 @@
warning: label name `'many_used_shadowed` shadows a label name that is already in scope
--> $DIR/unused_labels.rs:62:9
--> $DIR/unused_labels.rs:61:9
|
LL | 'many_used_shadowed: for _ in 0..10 {
| ------------------- first declared here
@ -8,55 +8,55 @@ LL | 'many_used_shadowed: for _ in 0..10 {
| ^^^^^^^^^^^^^^^^^^^ label `'many_used_shadowed` already in scope
warning: unused label
--> $DIR/unused_labels.rs:11:5
--> $DIR/unused_labels.rs:10:5
|
LL | 'unused_while_label: while 0 == 0 {
| ^^^^^^^^^^^^^^^^^^^
|
note: the lint level is defined here
--> $DIR/unused_labels.rs:8:9
--> $DIR/unused_labels.rs:7:9
|
LL | #![warn(unused_labels)]
| ^^^^^^^^^^^^^
warning: unused label
--> $DIR/unused_labels.rs:16:5
--> $DIR/unused_labels.rs:15:5
|
LL | 'unused_while_let_label: while let Some(_) = opt {
| ^^^^^^^^^^^^^^^^^^^^^^^
warning: unused label
--> $DIR/unused_labels.rs:20:5
--> $DIR/unused_labels.rs:19:5
|
LL | 'unused_for_label: for _ in 0..10 {
| ^^^^^^^^^^^^^^^^^
warning: unused label
--> $DIR/unused_labels.rs:36:9
--> $DIR/unused_labels.rs:35:9
|
LL | 'unused_loop_label_inner_2: for _ in 0..10 {
| ^^^^^^^^^^^^^^^^^^^^^^^^^^
warning: unused label
--> $DIR/unused_labels.rs:42:5
--> $DIR/unused_labels.rs:41:5
|
LL | 'unused_loop_label_outer_3: for _ in 0..10 {
| ^^^^^^^^^^^^^^^^^^^^^^^^^^
warning: unused label
--> $DIR/unused_labels.rs:60:5
--> $DIR/unused_labels.rs:59:5
|
LL | 'many_used_shadowed: for _ in 0..10 {
| ^^^^^^^^^^^^^^^^^^^
warning: unused label
--> $DIR/unused_labels.rs:72:5
--> $DIR/unused_labels.rs:71:5
|
LL | 'unused_loop_label: loop {
| ^^^^^^^^^^^^^^^^^^
warning: unused label
--> $DIR/unused_labels.rs:78:5
--> $DIR/unused_labels.rs:77:5
|
LL | 'unused_block_label: {
| ^^^^^^^^^^^^^^^^^^^

1
src/test/ui/macros/stringify.rs
View File

@ -9,7 +9,6 @@
#![feature(decl_macro)]
#![feature(generators)]
#![feature(half_open_range_patterns)]
#![feature(label_break_value)]
#![feature(more_qualified_paths)]
#![feature(raw_ref_op)]
#![feature(trait_alias)]

2
src/test/ui/parser/bad-interpolated-block.rs
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@ -1,5 +1,3 @@
#![feature(label_break_value)]
fn main() {}
macro_rules! m {

6
src/test/ui/parser/bad-interpolated-block.stderr
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@ -1,5 +1,5 @@
error: cannot use a `block` macro fragment here
--> $DIR/bad-interpolated-block.rs:7:15
--> $DIR/bad-interpolated-block.rs:5:15
|
LL | 'lab: $b;
| ------^^
@ -12,7 +12,7 @@ LL | m!({});
= note: this error originates in the macro `m` (in Nightly builds, run with -Z macro-backtrace for more info)
error: cannot use a `block` macro fragment here
--> $DIR/bad-interpolated-block.rs:8:16
--> $DIR/bad-interpolated-block.rs:6:16
|
LL | unsafe $b;
| -------^^
@ -25,7 +25,7 @@ LL | m!({});
= note: this error originates in the macro `m` (in Nightly builds, run with -Z macro-backtrace for more info)
error: cannot use a `block` macro fragment here
--> $DIR/bad-interpolated-block.rs:9:23
--> $DIR/bad-interpolated-block.rs:7:23
|
LL | |x: u8| -> () $b;
| ^^ the `block` fragment is within this context

2
src/test/ui/parser/labeled-no-colon-expr.rs
View File

@ -1,5 +1,3 @@
#![feature(label_break_value)]
fn main() {
'l0 while false {} //~ ERROR labeled expression must be followed by `:`
'l1 for _ in 0..1 {} //~ ERROR labeled expression must be followed by `:`

16
src/test/ui/parser/labeled-no-colon-expr.stderr
View File

@ -1,5 +1,5 @@
error: labeled expression must be followed by `:`
--> $DIR/labeled-no-colon-expr.rs:4:5
--> $DIR/labeled-no-colon-expr.rs:2:5
|
LL | 'l0 while false {}
| ----^^^^^^^^^^^^^^
@ -10,7 +10,7 @@ LL | 'l0 while false {}
= note: labels are used before loops and blocks, allowing e.g., `break 'label` to them
error: labeled expression must be followed by `:`
--> $DIR/labeled-no-colon-expr.rs:5:5
--> $DIR/labeled-no-colon-expr.rs:3:5
|
LL | 'l1 for _ in 0..1 {}
| ----^^^^^^^^^^^^^^^^
@ -21,7 +21,7 @@ LL | 'l1 for _ in 0..1 {}
= note: labels are used before loops and blocks, allowing e.g., `break 'label` to them
error: labeled expression must be followed by `:`
--> $DIR/labeled-no-colon-expr.rs:6:5
--> $DIR/labeled-no-colon-expr.rs:4:5
|
LL | 'l2 loop {}
| ----^^^^^^^
@ -32,7 +32,7 @@ LL | 'l2 loop {}
= note: labels are used before loops and blocks, allowing e.g., `break 'label` to them
error: labeled expression must be followed by `:`
--> $DIR/labeled-no-colon-expr.rs:7:5
--> $DIR/labeled-no-colon-expr.rs:5:5
|
LL | 'l3 {}
| ----^^
@ -43,7 +43,7 @@ LL | 'l3 {}
= note: labels are used before loops and blocks, allowing e.g., `break 'label` to them
error: expected `while`, `for`, `loop` or `{` after a label
--> $DIR/labeled-no-colon-expr.rs:8:9
--> $DIR/labeled-no-colon-expr.rs:6:9
|
LL | 'l4 0;
| ^ expected `while`, `for`, `loop` or `{` after a label
@ -55,7 +55,7 @@ LL + 0;
|
error: labeled expression must be followed by `:`
--> $DIR/labeled-no-colon-expr.rs:8:9
--> $DIR/labeled-no-colon-expr.rs:6:9
|
LL | 'l4 0;
| ----^
@ -66,7 +66,7 @@ LL | 'l4 0;
= note: labels are used before loops and blocks, allowing e.g., `break 'label` to them
error: cannot use a `block` macro fragment here
--> $DIR/labeled-no-colon-expr.rs:13:17
--> $DIR/labeled-no-colon-expr.rs:11:17
|
LL | 'l5 $b;
| ----^^
@ -79,7 +79,7 @@ LL | m!({});
= note: this error originates in the macro `m` (in Nightly builds, run with -Z macro-backtrace for more info)
error: labeled expression must be followed by `:`
--> $DIR/labeled-no-colon-expr.rs:16:8
--> $DIR/labeled-no-colon-expr.rs:14:8
|
LL | 'l5 $b;
| ---- help: add `:` after the label

1
src/test/ui/parser/recover-labeled-non-block-expr.fixed
View File

@ -1,5 +1,4 @@
// run-rustfix
#![feature(label_break_value)]
fn main() {
let _ = 1 + 1; //~ ERROR expected `while`, `for`, `loop` or `{` after a label

1
src/test/ui/parser/recover-labeled-non-block-expr.rs
View File

@ -1,5 +1,4 @@
// run-rustfix
#![feature(label_break_value)]
fn main() {
let _ = 'label: 1 + 1; //~ ERROR expected `while`, `for`, `loop` or `{` after a label

12
src/test/ui/parser/recover-labeled-non-block-expr.stderr
View File

@ -1,5 +1,5 @@
error: expected `while`, `for`, `loop` or `{` after a label
--> $DIR/recover-labeled-non-block-expr.rs:4:21
--> $DIR/recover-labeled-non-block-expr.rs:3:21
|
LL | let _ = 'label: 1 + 1;
| ^ expected `while`, `for`, `loop` or `{` after a label
@ -11,7 +11,7 @@ LL + let _ = 1 + 1;
|
error: expected `while`, `for`, `loop` or `{` after a label
--> $DIR/recover-labeled-non-block-expr.rs:6:13
--> $DIR/recover-labeled-non-block-expr.rs:5:13
|
LL | 'label: match () { () => {}, };
| ^^^^^ expected `while`, `for`, `loop` or `{` after a label
@ -23,7 +23,7 @@ LL + match () { () => {}, };
|
error: expected `while`, `for`, `loop` or `{` after a label
--> $DIR/recover-labeled-non-block-expr.rs:7:13
--> $DIR/recover-labeled-non-block-expr.rs:6:13
|
LL | 'label: match () { () => break 'label, };
| ^^^^^ expected `while`, `for`, `loop` or `{` after a label
@ -34,7 +34,7 @@ LL | 'label: { match () { () => break 'label, } };
| + +
error: expected `while`, `for`, `loop` or `{` after a label
--> $DIR/recover-labeled-non-block-expr.rs:9:13
--> $DIR/recover-labeled-non-block-expr.rs:8:13
|
LL | 'label: match () { () => 'lp: loop { break 'lp 0 }, };
| ^^^^^ expected `while`, `for`, `loop` or `{` after a label
@ -45,7 +45,7 @@ LL | 'label: { match () { () => 'lp: loop { break 'lp 0 }, } };
| + +
error: expected `while`, `for`, `loop` or `{` after a label
--> $DIR/recover-labeled-non-block-expr.rs:12:22
--> $DIR/recover-labeled-non-block-expr.rs:11:22
|
LL | let _i = 'label: match x {
| ^^^^^ expected `while`, `for`, `loop` or `{` after a label
@ -60,7 +60,7 @@ LL ~ } };
|
error: expected `while`, `for`, `loop` or `{` after a label
--> $DIR/recover-labeled-non-block-expr.rs:26:24
--> $DIR/recover-labeled-non-block-expr.rs:25:24
|
LL | let _val = 'label: (1, if other == 3 { break 'label (2, 3) } else { other });
| ^ expected `while`, `for`, `loop` or `{` after a label

1
src/tools/clippy/tests/ui/semicolon_if_nothing_returned.rs
View File

@ -1,6 +1,5 @@
#![warn(clippy::semicolon_if_nothing_returned)]
#![allow(clippy::redundant_closure)]
#![feature(label_break_value)]
#![feature(let_else)]
fn get_unit() {}

10
src/tools/clippy/tests/ui/semicolon_if_nothing_returned.stderr
View File

@ -1,5 +1,5 @@
error: consider adding a `;` to the last statement for consistent formatting
--> $DIR/semicolon_if_nothing_returned.rs:10:5
--> $DIR/semicolon_if_nothing_returned.rs:9:5
|
LL | println!("Hello")
| ^^^^^^^^^^^^^^^^^ help: add a `;` here: `println!("Hello");`
@ -7,25 +7,25 @@ LL | println!("Hello")
= note: `-D clippy::semicolon-if-nothing-returned` implied by `-D warnings`
error: consider adding a `;` to the last statement for consistent formatting
--> $DIR/semicolon_if_nothing_returned.rs:14:5
--> $DIR/semicolon_if_nothing_returned.rs:13:5
|
LL | get_unit()
| ^^^^^^^^^^ help: add a `;` here: `get_unit();`
error: consider adding a `;` to the last statement for consistent formatting
--> $DIR/semicolon_if_nothing_returned.rs:19:5
--> $DIR/semicolon_if_nothing_returned.rs:18:5
|
LL | y = x + 1
| ^^^^^^^^^ help: add a `;` here: `y = x + 1;`
error: consider adding a `;` to the last statement for consistent formatting
--> $DIR/semicolon_if_nothing_returned.rs:25:9
--> $DIR/semicolon_if_nothing_returned.rs:24:9
|
LL | hello()
| ^^^^^^^ help: add a `;` here: `hello();`
error: consider adding a `;` to the last statement for consistent formatting
--> $DIR/semicolon_if_nothing_returned.rs:36:9
--> $DIR/semicolon_if_nothing_returned.rs:35:9
|
LL | ptr::drop_in_place(s.as_mut_ptr())
| ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^ help: add a `;` here: `ptr::drop_in_place(s.as_mut_ptr());`

2
src/tools/rustfmt/tests/source/issue-3217.rs
View File

@ -1,5 +1,3 @@
#![feature(label_break_value)]
fn main() {
let mut res = 0;
's_39: { if res == 0i32 { println!("Hello, world!"); } }

2
src/tools/rustfmt/tests/target/issue-3217.rs
View File

@ -1,5 +1,3 @@
#![feature(label_break_value)]
fn main() {
let mut res = 0;
's_39: {