Rollup of 5 pull requests #124258
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Rollup of 5 pull requests #124258
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…ing `yield` expressions
And suggest adding the `#[coroutine]` to the closure
Stabilise inline_const
# Stabilisation Report
## Summary
This PR will stabilise `inline_const` feature in expression position. `inline_const_pat` is still unstable and will *not* be stabilised.
The feature will allow code like this:
```rust
foo(const { 1 + 1 })
```
which is roughly desugared into
```rust
struct Foo;
impl Foo {
const FOO: i32 = 1 + 1;
}
foo(Foo::FOO)
```
This feature is from rust-lang/rfcs#2920 and is tracked in rust-lang#76001 (the tracking issue should *not* be closed as it needs to track inline const in pattern position). The initial implementation is done in rust-lang#77124.
## Difference from RFC
There are two major differences (enhancements) as implemented from the RFC. First thing is that the RFC says that the type of an inline const block inferred from the content *within* it, but we currently can infer the type using the information from outside the const block as well. This is a frequently requested feature to the initial implementation (e.g. rust-lang#89964). The inference is implemented in rust-lang#89561 and is done by treating inline const similar to a closure and therefore share inference context with its parent body.
This allows code like:
```rust
let v: Vec<i32> = const { Vec::new() };
```
Another enhancement that differs from the RFC is that we currently allow inline consts to reference generic parameters. This is implemented in rust-lang#96557.
This allows code like:
```rust
fn create_none_array<T, const N: usize>() -> [Option<T>; N] {
[const { None::<T> }; N]
}
```
This enhancement also makes inline const usable as static asserts:
```rust
fn require_zst<T>() {
const { assert!(std::mem::size_of::<T>() == 0) }
}
```
## Documentation
Reference: rust-lang/reference#1295
## Unresolved issues
We still have a few issues that are not resolved, but I don't think it necessarily has to block stabilisation:
* expr fragment specifier issue: rust-lang#86730
* ~~`const {}` behaves similar to `async {}` but not to `{}` and `unsafe {}` (they are treated as `ExpressionWithoutBlock` rather than `ExpressionWithBlock`): https://rust-lang.zulipchat.com/#narrow/stream/213817-t-lang/topic/const.20blocks.20differ.20from.20normal.20and.20from.20unsafe.20blocks/near/290229453~~
## Tests
There are a few tests in https://github.com/rust-lang/rust/tree/master/src/test/ui/inline-const
…iler-errors Require explicitly marking closures as coroutines instead of relying on patching up the closure to be a coroutine if it happens to contain a `yield` expression. I only do this in the 2024 edition, as the `gen` keyword is only available there.
…=compiler-errors Fix ICE when ADT tail has type error Fixes rust-lang#124031
…-obk [cleanup] [llvm backend] Prevent creating the same `Instance::mono` multiple times Just a little thing I came across while going through the code. r? `@oli-obk`
…=oli-obk Miri: detect wrong vtables in wide pointers Fixes rust-lang/miri#3497. Needed to catch the UB that rust-lang#123572 will start exploiting. r? `@oli-obk`
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@bors r+ p=5 rollup=never |
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Apr 22, 2024
…llaumeGomez Rollup of 5 pull requests Successful merges: - rust-lang#104087 (Stabilise inline_const) - rust-lang#123792 (Require explicitly marking closures as coroutines) - rust-lang#124057 (Fix ICE when ADT tail has type error) - rust-lang#124178 ([cleanup] [llvm backend] Prevent creating the same `Instance::mono` multiple times) - rust-lang#124220 (Miri: detect wrong vtables in wide pointers) r? `@ghost` `@rustbot` modify labels: rollup
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The job Click to see the possible cause of the failure (guessed by this bot) |
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💔 Test failed - checks-actions |
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@GuillaumeGomez: It would be useful if you ping the PR that causes the issue and r- it, rather than just reopening a new one without the PR you're suspicious of |
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I am still going through the suspicious ones, hence why I didn't comment yet. |
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Successful merges:
Instance::monomultiple times #124178 ([cleanup] [llvm backend] Prevent creating the sameInstance::monomultiple times)r? @ghost
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