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This reverts commit 326646074940222d602f3683d0559088690830f4.
This is the revert against master, the beta revert was already done in #100538.
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Avoid cloning a collection only to iterate over it
`@rustbot` label: +C-cleanup
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Parser will not suggest invalid expression when use public
Fixes #100165
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Stabilize `#![feature(label_break_value)]`
See the stabilization report in https://github.com/rust-lang/rust/issues/48594#issuecomment-1186213313.
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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:
- https://github.com/rust-lang/rust/blob/d695a497bbf4b20d2580b75075faa80230d41667/src/test/ui/feature-gates/feature-gate-label_break_value.rs
+ Diagnostics:
- https://github.com/rust-lang/rust/blob/6b2d3d5f3cd1e553d87b5496632132565b6779d3/compiler/rustc_parse/src/parser/diagnostics.rs#L2629
- https://github.com/rust-lang/rust/blob/f65bf0b2bb1a99f73095c01a118f3c37d3ee614c/compiler/rustc_resolve/src/diagnostics.rs#L749
- https://github.com/rust-lang/rust/blob/f65bf0b2bb1a99f73095c01a118f3c37d3ee614c/compiler/rustc_resolve/src/diagnostics.rs#L1001
- https://github.com/rust-lang/rust/blob/111df9e6eda1d752233482c1309d00d20a4bbf98/compiler/rustc_passes/src/loops.rs#L254
- https://github.com/rust-lang/rust/blob/d695a497bbf4b20d2580b75075faa80230d41667/compiler/rustc_parse/src/parser/expr.rs#L2079
- https://github.com/rust-lang/rust/blob/d695a497bbf4b20d2580b75075faa80230d41667/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
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r=petrochenkov
Minor `ast::LitKind` improvements
r? `@petrochenkov`
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Because it's never used meaningfully.
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TaKO8Ki:suggest-adding-missing-semicolon-before-item, r=compiler-errors
Suggest adding a missing semicolon before an item
fixes #100533
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Convert diagnostics in parser/expr to SessionDiagnostic
This migrates all the easy cases in `rustc_parse::parser::expr` to `SessionDiagnostic`s, I've left things such as `multipart_suggestion`s out for now in the hopes of a derive API being developed soon.
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Recover keywords in trait bounds
(_this pr was inspired by [this tweet](https://twitter.com/Azumanga/status/1552982326409367561)_)
Recover keywords in trait bound, motivational example:
```rust
fn f(_: impl fn()) {} // mistyped, meant `Fn`
```
<details><summary>Current nightly (3 needless and confusing errors!)</summary>
<p>
```text
error: expected identifier, found keyword `fn`
--> ./t.rs:1:15
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1 | fn _f(_: impl fn()) {}
| ^^ expected identifier, found keyword
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help: escape `fn` to use it as an identifier
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1 | fn _f(_: impl r#fn()) {}
| ++
error: expected one of `:` or `|`, found `)`
--> ./t.rs:1:19
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1 | fn _f(_: impl fn()) {}
| ^ expected one of `:` or `|`
error: expected one of `!`, `(`, `)`, `,`, `?`, `for`, `~`, lifetime, or path, found keyword `fn`
--> ./t.rs:1:15
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1 | fn _f(_: impl fn()) {}
| -^^ expected one of 9 possible tokens
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| help: missing `,`
error: at least one trait must be specified
--> ./t.rs:1:10
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1 | fn _f(_: impl fn()) {}
| ^^^^
```
</p>
</details>
This PR:
```text
error: expected identifier, found keyword `fn`
--> ./t.rs:1:15
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1 | fn _f(_: impl fn()) {}
| ^^ expected identifier, found keyword
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help: escape `fn` to use it as an identifier
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1 | fn _f(_: impl r#fn()) {}
| ++
error[E0405]: cannot find trait `r#fn` in this scope
--> ./t.rs:1:15
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1 | fn _f(_: impl fn()) {}
| ^^ help: a trait with a similar name exists (notice the capitalization): `Fn`
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::: /home/waffle/projects/repos/rust/library/core/src/ops/function.rs:74:1
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74 | pub trait Fn<Args>: FnMut<Args> {
| ------------------------------- similarly named trait `Fn` defined here
```
It would be nice to have suggestion in the first error like "have you meant `Fn` trait", instead of a separate error, but the recovery is deep inside ident parsing, which makes it a lot harder to do.
r? `@compiler-errors`
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In some places we use `Vec<Attribute>` and some places we use
`ThinVec<Attribute>` (a.k.a. `AttrVec`). This results in various points
where we have to convert between `Vec` and `ThinVec`.
This commit changes the places that use `Vec<Attribute>` to use
`AttrVec`. A lot of this is mechanical and boring, but there are
some interesting parts:
- It adds a few new methods to `ThinVec`.
- It implements `MapInPlace` for `ThinVec`, and introduces a macro to
avoid the repetition of this trait for `Vec`, `SmallVec`, and
`ThinVec`.
Overall, it makes the code a little nicer, and has little effect on
performance. But it is a precursor to removing
`rustc_data_structures::thin_vec::ThinVec` and replacing it with
`thin_vec::ThinVec`, which is implemented more efficiently.
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Box the `MacCall` in various types.
r? `@spastorino`
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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
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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.
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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.
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Clean up `LitKind`
r? ``@petrochenkov``
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Something seems to have gotten out of sync during the creation of #81177,
where both the argument and comment were introduced.
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- 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`.
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These fields are unused.
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Parser simplifications
Best reviewed one commit at a time.
r? ``@compiler-errors``
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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. :shrug: Thoughts?
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Use `create_snapshot_for_diagnostic` instead of `clone` for `Parser`
follow-up to #98020
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Make code slightly more uniform
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`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.
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Let-chaining avoids some code duplication.
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Recover from mutable variable declaration where `mut` is placed before `let`
Closes #100197
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Suggest removing `let` if `const let` or `let const` is used
Closes #99910
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TaKO8Ki:suggest-removing-semicolon-after-impl-trait-items, r=compiler-errors
Suggest removing a semicolon after impl/trait items
fixes #99822
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r=estebank
Only point out a single function parameter if we have a single arg incompatibility
Fixes #99635
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Give a helpful diagnostic when the next struct field has an attribute
Fixes #100461
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Suggest const and static for global variable
Fixing #100394
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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
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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.
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