This message is no longer generated.
This is probably a good thing. The relevant span is entirely in user
code, and "format_args_nl" is an implementation detail with a name that
isn't even public.
These tests necessarily need to change now that `?Sized` is not
sufficient to accept extern types and `PointeeSized` is now necessary. In
addition, the `size_of_val`/`align_of_val` test can now be changed to
expect an error.
Temporary lifetime extension through tuple struct and tuple variant constructors
This makes temporary lifetime extension work for tuple struct and tuple variant constructors, such as `Some()`.
Before:
```rust
let a = &temp(); // Extended
let a = Some(&temp()); // Not extended :(
let a = Some { 0: &temp() }; // Extended
```
After:
```rust
let a = &temp(); // Extended
let a = Some(&temp()); // Extended
let a = Some { 0: &temp() }; // Extended
```
So, with this change, this works:
```rust
let a = Some(&String::from("hello")); // New: String lifetime now extended!
println!("{a:?}");
```
Until now, we did not extend through tuple struct/variant constructors (like `Some`), because they are function calls syntactically, and we do not want to extend the String lifetime in:
```rust
let a = some_function(&String::from("hello")); // String not extended!
```
However, it turns out to be very easy to distinguish between regular functions and constructors at the point where we do lifetime extension.
In practice, constructors nearly always use UpperCamelCase while regular functions use lower_snake_case, so it should still be easy to for a human programmer at the call site to see whether something qualifies for lifetime extension or not.
This needs a lang fcp.
---
More examples of what will work after this change:
```rust
let x = Person {
name: "Ferris",
job: Some(&Job { // `Job` now extended!
title: "Chief Rustacean",
organisation: "Acme Ltd.",
}),
};
dbg!(x);
```
```rust
let file = if use_stdout {
None
} else {
Some(&File::create("asdf")?) // `File` now extended!
};
set_logger(file);
```
```rust
use std::path::Component;
let c = Component::Normal(&OsString::from(format!("test-{num}"))); // OsString now extended!
assert_eq!(path.components.first().unwrap(), c);
```
refactor `AttributeGate` and `rustc_attr!` to emit notes during feature checking
First commit changes the following:
- `AttributeGate ` from an enum with (four) tuple fields to (five) named fields
- adds a `notes` fields that is emitted as notes in the `PostExpansionVisitor` pass
- removes the `this compiler was built on YYYY-MM-DD; consider upgrading it if it is out of date` note if the feature gate is `rustc_attrs`.
- various phrasing changes and touchups
- and finally, the reason why I went down this path to begin with: tell people they can use the diagnostic namespace when they hit the rustc_on_unimplemented feature gate 🙈
Second commit removes unused machinery for deprecated attributes
const-eval error: always say in which item the error occurred
I don't see why "is this generic" should make a difference. It may be reasonable to key this on whether the error occurs in a `const fn` that was invoked by a const (making it non-obvious which constant it is) vs inside the body of the const.
r? `@oli-obk`
Make obligation cause code suggestions verbose
```
error[E0277]: `()` is not a future
--> $DIR/unnecessary-await.rs:28:10
|
LL | e!().await;
| ^^^^^ `()` is not a future
|
= help: the trait `Future` is not implemented for `()`
= note: () must be a future or must implement `IntoFuture` to be awaited
= note: required for `()` to implement `IntoFuture`
help: remove the `.await`
|
LL - e!().await;
LL + e!();
|
```
```
error[E0277]: the trait bound `String: Copy` is not satisfied
--> $DIR/const-fn-in-vec.rs:1:47
|
LL | static _MAYBE_STRINGS: [Option<String>; 5] = [None; 5];
| ^^^^ the trait `Copy` is not implemented for `String`
|
= note: required for `Option<String>` to implement `Copy`
= note: the `Copy` trait is required because this value will be copied for each element of the array
help: create an inline `const` block
|
LL | static _MAYBE_STRINGS: [Option<String>; 5] = [const { None }; 5];
| +++++++ +
```
Part of rust-lang/rust#141973
```
error[E0277]: `()` is not a future
--> $DIR/unnecessary-await.rs:28:10
|
LL | e!().await;
| ^^^^^ `()` is not a future
|
= help: the trait `Future` is not implemented for `()`
= note: () must be a future or must implement `IntoFuture` to be awaited
= note: required for `()` to implement `IntoFuture`
help: remove the `.await`
|
LL - e!().await;
LL + e!();
|
```
```
error[E0277]: the trait bound `String: Copy` is not satisfied
--> $DIR/const-fn-in-vec.rs:1:47
|
LL | static _MAYBE_STRINGS: [Option<String>; 5] = [None; 5];
| ^^^^ the trait `Copy` is not implemented for `String`
|
= note: required for `Option<String>` to implement `Copy`
= note: the `Copy` trait is required because this value will be copied for each element of the array
help: create an inline `const` block
|
LL | static _MAYBE_STRINGS: [Option<String>; 5] = [const { None }; 5];
| +++++++ +
```
Make two transmute-related MIR lints into HIR lint
Make `PTR_TO_INTEGER_TRANSMUTE_IN_CONSTS` (rust-lang/rust#130540) and `UNNECESSARY_TRANSMUTES` (rust-lang/rust#136083) into "normal" HIR-based lints.
Funny enough this came up in the review of the latter (https://github.com/rust-lang/rust/pull/136083#issuecomment-2614301413), but I guess it just was overlooked.
But anywyas, there's no reason for these to be MIR lints; in fact, it makes the suggestions for them a bit more complicated than necessary.
Note that there's probably a few more simplifications and improvements to be done here. Follow-ups can be done in a separate PR, especially if they're about the messaging and suggestions themselves, which I didn't write.
Add some track_caller info to precondition panics
Currently, when you encounter a precondition check, you'll always get the caller location of the implementation of the precondition checks. But with this PR, you'll be told the location of the invalid call. Which is useful.
I thought of this while looking at https://github.com/rust-lang/rust/pull/129642#issuecomment-2311703898.
The changes to `tests/ui/const*` happen because the const-eval interpreter skips `#[track_caller]` frames in its backtraces.
The perf implications of this are:
* Increased debug binary sizes. The caller_location implementation requires that the additional data we want to display here be stored in const allocations, which are deduplicated but not across crates. There is no impact on optimized build sizes. The panic path and the caller location data get optimized out.
* The compile time hit to opt-incr-patched bitmaps happens because the patch changes the line number of some function calls with precondition checks, causing us to go from 0 dirty CGUs to 1 dirty CGU.
* The other compile time hits are marginal but real, and due to doing a handful of new queries. Adding more useful data isn't completely free.
remove intrinsics::drop_in_place
This was only ever accidentally stable, and has been marked as deprecated since Rust 1.52, released almost 4 years ago. We've removed the old serialization `derive`s, maybe we can remove this one as well?
As suggested by ``@jhpratt,`` let's see what crater says for this one.
stabilize ptr::swap_nonoverlapping in const
Closes https://github.com/rust-lang/rust/issues/133668
The blocking issue mentioned there is resolved by documentation. We may in the future actually support such code, but that is blocked on https://github.com/rust-lang/const-eval/issues/72 which is non-trivial to implement. Meanwhile, this completes stabilization of all `const fn` in `ptr`. :)
Here's a version of the problematic example to play around with:
https://play.rust-lang.org/?version=nightly&mode=debug&edition=2021&gist=6c390452379fb593e109b8f8ee854d2a
Should be FCP'd with both `@rust-lang/libs-api` and `@rust-lang/lang` since `swap_nonoverlapping` is documented to work as an "untyped" operation but due to the limitation mentioned above, that's not entirely true during const evaluation. I expect this limitation will only be hit in niche corner cases, so the benefits of having this function work most of the time outweigh the downsides of users running into this problem. (Note that unsafe code could already hit this limitation before this PR by doing cursed pointer casts, but having it hidden inside `swap_nonoverlapping` feels a bit different.)
Don't allow flattened format_args in const.
Fixes https://github.com/rust-lang/rust/issues/139136
Fixes https://github.com/rust-lang/rust/issues/139621
We allow `format_args!("a")` in const, but don't allow any format_args with arguments in const, such as `format_args!("{}", arg)`.
However, we accidentally allow `format_args!("hello {}", "world")` in const, as it gets flattened to `format_args!("hello world")`.
This also applies to panic in const.
This wasn't supposed to happen. I added protection against this in the format args flattening code, ~~but I accidentally marked a function as const that shouldn't have been const~~ but this was removed in https://github.com/rust-lang/rust/pull/135139.
This is a breaking change. The crater found no breakage, however.
This breaks things like:
```rust
const _: () = if false { panic!("a {}", "a") };
```
and
```rust
const F: std::fmt::Arguments<'static> = format_args!("a {}", "a");
```
Stabilize `cfg_boolean_literals`
Closes#131204
`@rustbot` labels +T-lang +I-lang-nominated
This will end up conflicting with the test in #138293 so whichever doesn't land first will need updating
--
# Stabilization Report
## General design
### What is the RFC for this feature and what changes have occurred to the user-facing design since the RFC was finalized?
[RFC 3695](https://github.com/rust-lang/rfcs/pull/3695), none.
### What behavior are we committing to that has been controversial? Summarize the major arguments pro/con.
None
### Are there extensions to this feature that remain unstable? How do we know that we are not accidentally committing to those?
None
## Has a call-for-testing period been conducted? If so, what feedback was received?
Yes; only positive feedback was received.
## Implementation quality
### Summarize the major parts of the implementation and provide links into the code (or to PRs)
Implemented in [#131034](https://github.com/rust-lang/rust/pull/131034).
### Summarize existing test coverage of this feature
- [Basic usage, including `#[cfg()]`, `cfg!()` and `#[cfg_attr()]`](6d71251cf9/tests/ui/cfg/true-false.rs)
- [`--cfg=true/false` on the command line being accessible via `r#true/r#false`](6d71251cf9/tests/ui/cfg/raw-true-false.rs)
- [Interaction with the unstable `#[doc(cfg(..))]` feature](6d71251/tests/rustdoc-ui/cfg-boolean-literal.rs)
- [Denying `--check-cfg=cfg(true/false)`](6d71251/tests/ui/check-cfg/invalid-arguments.rs)
- Ensuring `--cfg false` on the command line doesn't change the meaning of `cfg(false)`: `tests/ui/cfg/cmdline-false.rs`
- Ensuring both `cfg(true)` and `cfg(false)` on the same item result in it being disabled: `tests/ui/cfg/both-true-false.rs`
### What outstanding bugs in the issue tracker involve this feature? Are they stabilization-blocking?
The above mentioned issue; it should not block as it interacts with another unstable feature.
### What FIXMEs are still in the code for that feature and why is it ok to leave them there?
None
### Summarize contributors to the feature by name for recognition and assuredness that people involved in the feature agree with stabilization
- `@clubby789` (RFC)
- `@Urgau` (Implementation in rustc)
### Which tools need to be adjusted to support this feature. Has this work been done?
`rustdoc`'s unstable`#[doc(cfg(..)]` has been updated to respect it. `cargo` has been updated with a forward compatibility lint to enable supporting it in cargo once stabilized.
## Type system and execution rules
### What updates are needed to the reference/specification? (link to PRs when they exist)
A few lines to be added to the reference for configuration predicates, specified in the RFC.
UI tests: migrate remaining compile time `error-pattern`s to line annotations when possible
There's a number of cases in which `error-pattern` is still necessary even for compile time checking.
- It checks something that compiler writes directly into stderr as text, and not to the structured json output. This includes some stuff reported during compiler panics, and also diagnostics that happen very early, for example when parsing the command line.
- It checks something that exists only in the full rendered diagnostic test, but not in its structured components, for example code fragments or output of `-Ztrack-diagnostics`. (The latter can probably be converted to structured form though.)
This is continuation of https://github.com/rust-lang/rust/pull/139137.
r? `@jieyouxu`
