smoke-test for async fn with mir-opt-level=0
MIR opt levels heavily influence which MIR transformations run, and we barely test non-default opt levels. I am particularly worried about `async fn` lowering and how it might (not) work when the set of preceding MIR passes changes -- see https://github.com/rust-lang/rust/pull/70073.
This adds some basic smoke testing, where at least a few `async fn` `run-pass` test are ensured to also work with mir-opt-level=0.
Add a function to turn Box<T> into Box<[T]>
Hi,
I think this is very useful, as currently it's not possible in safe rust to do this without re-allocating.
an alternative implementation of the same function can be:
```rust
pub fn into_boxed_slice<T>(boxed: Box<T>) -> Box<[T]> {
unsafe {
let slice = slice::from_raw_parts_mut(Box::into_raw(boxed), 1);
Box::from_raw(slice)
}
}
```
The only thing that makes me a little uncomfortable is this line :
> The alignment of array types is greater or equal to the alignment of its element type
from https://rust-lang.github.io/unsafe-code-guidelines/layout/arrays-and-slices.html
But then I see:
> The alignment of &T, &mut T, *const T and *mut T are the same, and are at least the word size.
> The alignment of &[T] is the word size.
from https://rust-lang.github.io/unsafe-code-guidelines/layout/pointers.html#representation
So I do believe this is valid(FWIW it also passes in miri https://play.rust-lang.org/?gist=c002b99364ee6b29862aeb3565a91c19)
[breaking change] Disallow statics initializing themselves
fixes#71078
Self-initialization is unsound because it breaks privacy assumptions that unsafe code can make. In
```rust
pub mod foo {
#[derive(Debug, Copy, Clone)]
pub struct Foo {
x: (),
}
}
pub static FOO: foo::Foo = FOO;
```
unsafe could could expect that ony functions inside the `foo` module were able to create a value of type `Foo`.
Add all remaining `DefKind`s.
r? @eddyb or @Centril
~~I'm not sure if this is what you were thinking of. There are also a few places where I'm not sure what the correct choice is because I don't fully understand the meaning of some variants.~~
~~In general, it feels a bit odd to add some of these as `DefKind`s (e.g. `Arm`) because they don't feel like definitions. Are there things that it makes sense not to add?~~
Fix span of while (let) expressions after lowering
Credit goes to @alex-700 who found this while trying to fix a suggestion in Clippy.
While `if`, `try`, `for` and `await` expressions get the span of the original expression when desugared, `while` loops got the span of the scrutinee, which lead to weird code, when building the suggestion, that randomly worked: https://github.com/rust-lang/rust-clippy/pull/5511/files#diff-df4e9d2bf840a5f2e3b580bef73da3bcR106-R108
I'm wondering, if `DesugaringKind` should get a variant `WhileLoop` and instead of using the span of the `ast::ExprKind::While` expr directly, a new span with `self.mark_span_with_reason` should be used, like it is done with `for` loops.
There was some fallout, but I think that is acceptable. If not, I need some help to find out where this can be fixed.
Only run dataflow for const qualification if type-based check would fail
This is the optimization discussed in https://github.com/rust-lang/rust/issues/49146#issuecomment-614012476. We wait for `Qualif::in_any_value_of_ty` to return `true` before running dataflow. For bodies that deal mostly with primitive types, this will avoid running dataflow at all during const qualification.
This also removes the `BitSet` used to cache `in_any_value_of_ty` for each local, which was only necessary for an old version of #64470 that also handled promotability.
Stabilize UNICODE_VERSION (feature unicode_version)
Tracking issue: #49726
r? @sfackler
#71020 changed the definition of `UNICODE_VERSION` just yesterday from a struct to a tuple. Maybe you want to wait some more before stabilizing this constant, on the other hand this is a very small and simple addition.
CC @behnam @SimonSapin @Serentty
Make the `structural_match` error diagnostic for const generics clearer
The previous diagnostic caused confusion (https://github.com/rust-lang/rust/issues/70790), so this changes the message to be closer to the message for using non-`structural_match` constants in patterns, explicitly mentioning `#[derive(PartialEq, Eq)]`.
Fixes https://github.com/rust-lang/rust/issues/70790.
r? @estebank
Confusing suggestion on incorrect closing `}`
Compiler returns
```
error: unexpected closing delimiter: `}`
--> main.rs:20:1
|
9 | ErrorHandled::Reported => {}
| -- this block is empty, you might have not meant to close it temp
...
20 | }
| ^ unexpected closing delimiter
error: aborting due to previous error
```
Improve E0308 error message wording again
Hello again,
I recently did this PR: #70242
I felt the error message could be further improved, so I made [a post on the Rust community forum](https://users.rust-lang.org/t/looking-for-feedback-on-an-improved-error-message-for-e0308/40004) to ask for feedback.
(Also, there were some comments on my original PR that I took into consideration as well.)
This PR is my attempt to take all the feedback into account and propose a better and simplified error message that should still be accurate. Its main benefit is having simpler grammar, and hopefully being easier to read and understand.
Thanks to everyone who commented and gave feedback, and thank you for taking a look at this PR.
Reading from the return place is fine
Const eval thinks that reading from local `_0` is UB, but it isn't. `_0` is just a normal local like any other, and codegen handles it that way too. The only special thing is that the `Return` terminator will read from it.
I've hit these errors while working on an NRVO pass that can merge other locals with `_0` in https://github.com/rust-lang/rust/pull/71003.
r? @oli-obk
proc_macro::is_available()
This PR adds `proc_macro::is_available() -> bool` to determine whether proc_macro has been made accessible to the currently running program.
The proc_macro crate is only intended for use inside the implementation of procedural macros. All the functions in the crate panic if invoked from outside of a procedural macro, such as from a build script or unit test or ordinary Rust binary.
Unfortunately those panics made it impossible for libraries that are designed to support both macro and non-macro use cases (e.g. Syn) to be used from binaries that are compiled with panic=abort. In panic=unwind mode we're able to attempt a proc macro call inside catch_unwind and use libproc_macro's result if it succeeds, otherwise fall back to a non-macro alternative implementation. But in panic=abort there was no way to determine which implementation needs to be used.
r? @eddyb
attn: @petrochenkov @adetaylor
ref: https://github.com/dtolnay/cxx/issues/130
Lint must_use on mem::replace
This adds a hint on `mem::replace`, "if you don't need the old value,
you can just assign the new value directly". This is in similar spirit
to the `must_use` on `ManuallyDrop::take`.
