Handle discriminant in DataflowConstProp
cc ``@jachris``
r? ``@JakobDegen``
This PR attempts to extend the DataflowConstProp pass to handle propagation of discriminants. We handle this by adding 2 new variants to `TrackElem`: `TrackElem::Variant` for enum variants and `TrackElem::Discriminant` for the enum discriminant pseudo-place.
The difficulty is that the enum discriminant and enum variants may alias each another. This is the issue of the `Option<NonZeroUsize>` test, which is the equivalent of https://github.com/rust-lang/unsafe-code-guidelines/issues/84 with a direct write.
To handle that, we generalize the flood process to flood all the potentially aliasing places. In particular:
- any write to `(PLACE as Variant)`, either direct or through a projection, floods `(PLACE as OtherVariant)` for all other variants and `discriminant(PLACE)`;
- `SetDiscriminant(PLACE)` floods `(PLACE as Variant)` for each variant.
This implies that flooding is not hierarchical any more, and that an assignment to a non-tracked place may need to flood a tracked place. This is handled by `for_each_aliasing_place` which generalizes `preorder_invoke`.
As we deaggregate enums by putting `SetDiscriminant` last, this allows to propagate the value of the discriminant.
This refactor will allow to make https://github.com/rust-lang/rust/pull/107009 able to handle discriminants too.
Suggest the correct array length on mismatch
Fixes#107156
I wasn't able to find a way to get the `Span` for the actual array size unfortunately, so this suggestion can't be applied automatically.
``@rustbot`` label +A-diagnostics
rework min_choice algorithm of member constraints
See [this comment](https://github.com/rust-lang/rust/pull/105300#issuecomment-1384312743) for the description of the new algorithm.
Fixes#63033Fixes#104639
This uses a more general algorithm than #89056 that doesn't treat `'static` as a special case. It thus accepts more code. For example:
```rust
async fn test2<'s>(_: &'s u8, _: &'_ &'s u8, _: &'_ &'s u8) {}
```
I claim it's more correct as well because it fixes#104639.
cc ``@nikomatsakis`` ``@lqd`` ``@tmandry`` ``@eholk`` ``@chenyukang`` ``@oli-obk``
r? types
use semantic equality for const param type equality assertion
Fixes#107898
See added test for what caused this ICE
---
The current in assertion in `relate.rs` is rather inadequate when keeping in mind future expansions to const generics:
- it will ICE when there are infer vars in a projection in a const param ty
- it will spurriously return false when either ty has infer vars because of using `==` instead of `infcx.at(..).eq`
- i am also unsure if it would be possible with `adt_const_params` to craft a situation where the const param type is not wf causing `normalize_erasing_regions` to `bug!` when we would have emitted a diagnostic.
This impl feels pretty Not Great to me although i am not sure what a better idea would be.
- We have to have the logic behind a query because neither `relate.rs` or `combine.rs` have access to trait solving machinery (without evaluating nested obligations this assert will become _far_ less useful under lazy norm, which consts are already doing)
- `relate.rs` does not have access to canonicalization machinery which is necessary in order to have types potentially containing infer vars in query arguments.
We could possible add a method to `TypeRelation` to do this assertion rather than a query but to avoid implementing the same logic over and over we'd probably end up with the logic in a free function somewhere in `rustc_trait_selection` _anyway_ so I don't think that would be much better.
We could also just remove this assertion, it should not actually be necessary for it to be present. It has caught some bugs in the past though so if possible I would like to keep it.
r? `@compiler-errors`
add an unstable `#[rustc_coinductive]` attribute
useful to test coinduction, especially in the new solver.
as this attribute should remain permanently unstable I don't think this needs any official approval. cc ``@rust-lang/types``
had to weaken the check for stable query results in the solver to prevent an ICE if there's a coinductive cycle with constraints.
r? ``@compiler-errors``
Update the minimum external LLVM to 14
With this change, we'll have stable support for LLVM 14 through 16 (pending release).
For reference, the previous increase to LLVM 13 was #100460.
Suggest fix for misplaced generic params on fn item #103366fixes#103366
This still has some work to go, but works for 2/3 of the initial base cases described in #1033366
simple fn:
```
error: expected identifier, found `<`
--> shreys/test_1.rs:1:3
|
1 | fn<T> id(x: T) -> T { x }
| ^ expected identifier
|
help: help: place the generic parameter list after the function name:
|
1 | fn id<T>(x: T) -> T { x }
| ~~~~
```
Complicated bounds
```
error: expected identifier, found `<`
--> spanishpear/test_2.rs:1:3
|
1 | fn<'a, B: 'a + std::ops::Add<Output = u32>> f(_x: B) { }
| ^ expected identifier
|
help: help: place the generic parameter list after the function name:
|
1 | fn f<'a, B: 'a + std::ops::Add<Output = u32>>(_x: B) { }
| ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
```
Opening a draft PR for comments on approach, particularly I have the following questions:
- [x] Is it okay to be using `err.span_suggestion` over struct derives? I struggled to get the initial implementation (particularly the correct suggestion message) on struct derives, although I think given what I've learned since starting, I could attempt re-doing it with that approach.
- [x] in the case where the snippet cannot be obtained from a span, is the `help` but no suggestion okay? I think yes (also, when does this case occur?)
- [x] are there any red flags for the generalisation of this work for relevant item kinds (i.e. `struct`, `enum`, `trait`, and `union`). My basic testing indicates it does work for those types except the help tip is currently hardcoded to `after the function name` - which should change dependent on the item.
- [x] I am planning to not show the suggestion if there is already a `<` after the item identifier, (i.e. if there are already generics, as after a function name per the original issue). Any major objections?
- [x] Is the style of error okay? I wasn't sure if there was a way to make it display nicer, or if thats handled by span_suggestion
These aren't blocking questions, and I will keep working on:
- check if there is a `<` after the ident (and if so, not showing the suggestion)
- generalize the help message
- figuring out how to write/run/etc ui tests (including reading the docs for them)
- logic cleanups
Note that at the time of this commit, `unic-emoji-char` seems to have
data tables only up to Unicode 5.0, but Unicode is already newer than
this.
A newer emoji such as `🥺` will not be recognized as an emoji
but older emojis such as `🐱` will.
This commit makes intra-doc link tooltips consistent with generated
links in function signatures and item tables, with the format
`itemtype foo::bar::baz`. This way, you can tell if a link points at
a trait or a type (for example) by mousing over it.
See also fce944d4e7
Clearly document intentional UB in mir-opt tests
All of the changed mir-opt test input files did not pass Miri. Now they do.
r? `@cjgillot` because there's a CopyProp test in here that I do not fully understand
fix: improve the suggestion on future not awaited
Considering the following code
```rust
fn foo() -> u8 {
async fn async_fn() -> u8 { 22 }
async_fn()
}
fn main() {}
```
the error generated before this commit from the compiler is
```
➜ rust git:(macros/async_fn_suggestion) ✗ rustc test.rs --edition 2021
error[E0308]: mismatched types
--> test.rs:4:5
|
1 | fn foo() -> u8 {
| -- expected `u8` because of return type
...
4 | async_fn()
| ^^^^^^^^^^ expected `u8`, found opaque type
|
= note: expected type `u8`
found opaque type `impl Future<Output = u8>`
help: consider `await`ing on the `Future`
|
4 | async_fn().await
| ++++++
error: aborting due to previous error
```
In this case the error is nor perfect, and can confuse the user that do not know that the opaque type is the future.
So this commit will propose (and conclude the work start in https://github.com/rust-lang/rust/issues/80658)
to change the string `opaque type` to `future` when applicable and also remove the Expected vs Received note by adding a more specific one regarding the async function that return a future type.
So the new error emitted by the compiler is
```
error[E0308]: mismatched types
--> test.rs:4:5
|
1 | fn foo() -> u8 {
| -- expected `u8` because of return type
...
4 | async_fn()
| ^^^^^^^^^^ expected `u8`, found future
|
note: calling an async function returns a future
--> test.rs:4:5
|
4 | async_fn()
| ^^^^^^^^^^
help: consider `await`ing on the `Future`
|
4 | async_fn().await
| ++++++
error: aborting due to previous error
```
Fixes https://github.com/rust-lang/rust/issues/80658
It remains to rework the case described in the following issue https://github.com/rust-lang/rust/issues/107899 but I think this deserves its own PR after we discuss a little bit how to handle these kinds of cases.
r? `@eholk`
`@rustbot` label +I-async-nominated
Signed-off-by: Vincenzo Palazzo <vincenzopalazzodev@gmail.com>
Move folding & visiting traits into type library
This is a rework of #107712, following feedback on that PR.
In particular, this version uses trait aliases to reduce the API churn for trait consumers. Doing so requires a workaround for #107747 until its fix in #107803 is merged into the stage0 compiler; this workaround, which uses conditional compilation based on the `bootstrap` configuration predicate, sits in dedicated commit b409329c for ease of reversion.
The possibility of the `rustc_middle` crate retaining its own distinct versions of each folding/visiting trait, blanket-implemented on all types that implement the respective trait in the type library, was also explored: however since this would necessitate making each `rustc_middle` trait a subtrait of the respective type library trait (so that such blanket implementations can delegate their generic methods), no benefit would be gained.
r? types
Considering the following code
```rust
fn foo() -> u8 {
async fn async_fn() -> u8 { 22 }
async_fn()
}
fn main() {}
```
the error generated before this commit from the compiler is
```
➜ rust git:(macros/async_fn_suggestion) ✗ rustc test.rs --edition 2021
error[E0308]: mismatched types
--> test.rs:4:5
|
1 | fn foo() -> u8 {
| -- expected `u8` because of return type
...
4 | async_fn()
| ^^^^^^^^^^ expected `u8`, found opaque type
|
= note: expected type `u8`
found opaque type `impl Future<Output = u8>`
help: consider `await`ing on the `Future`
|
4 | async_fn().await
| ++++++
error: aborting due to previous error
```
In this case the error is nor perfect, and can confuse the user
that do not know that the opaque type is the future.
So this commit will propose (and conclude the work start in
https://github.com/rust-lang/rust/issues/80658)
to change the string `opaque type` to `future` when applicable
and also remove the Expected vs Received note by adding a more
specific one regarding the async function that return a future type.
So the new error emitted by the compiler is
```
error[E0308]: mismatched types
--> test.rs:4:5
|
1 | fn foo() -> u8 {
| -- expected `u8` because of return type
...
4 | async_fn()
| ^^^^^^^^^^ expected `u8`, found future
|
note: calling an async function returns a future
--> test.rs:4:5
|
4 | async_fn()
| ^^^^^^^^^^
help: consider `await`ing on the `Future`
|
4 | async_fn().await
| ++++++
error: aborting due to previous error
```
Signed-off-by: Vincenzo Palazzo <vincenzopalazzodev@gmail.com>
Rollup of 6 pull requests
Successful merges:
- #107340 (rustdoc: merge doctest tooltip with notable traits tooltip)
- #107838 (Introduce `-Zterminal-urls` to use OSC8 for error codes)
- #107922 (Print disk usage in PGO CI script)
- #107931 (Intern span when length is MAX_LEN with parent.)
- #107935 (rustc_ast: Merge impls and reorder methods for attributes and meta items)
- #107986 (layout: deal with placeholders, ICE on bound types)
Failed merges:
r? `@ghost`
`@rustbot` modify labels: rollup
Introduce `-Zterminal-urls` to use OSC8 for error codes
Terminals supporting the OSC8 Hyperlink Extension can support inline anchors where the text is user defineable but clicking on it opens a browser to a specified URLs, just like `<a href="URL">` does in HTML.
https://gist.github.com/egmontkob/eb114294efbcd5adb1944c9f3cb5feda
Improve the `array::map` codegen
The `map` method on arrays [is documented as sometimes performing poorly](https://doc.rust-lang.org/std/primitive.array.html#note-on-performance-and-stack-usage), and after [a question on URLO](https://users.rust-lang.org/t/try-trait-residual-o-trait-and-try-collect-into-array/88510?u=scottmcm) prompted me to take another look at the core [`try_collect_into_array`](7c46fb2111/library/core/src/array/mod.rs (L865-L912)) function, I had some ideas that ended up working better than I'd expected.
There's three main ideas in here, split over three commits:
1. Don't use `array::IntoIter` when we can avoid it, since that seems to not get SRoA'd, meaning that every step writes things like loop counters into the stack unnecessarily
2. Don't return arrays in `Result`s unnecessarily, as that doesn't seem to optimize away even with `unwrap_unchecked` (perhaps because it needs to get moved into a new LLVM type to account for the discriminant)
3. Don't distract LLVM with all the `Option` dances when we know for sure we have enough items (like in `map` and `zip`). This one's a larger commit as to do it I ended up adding a new `pub(crate)` trait, but hopefully those changes are still straight-forward.
(No libs-api changes; everything should be completely implementation-detail-internal.)
It's still not completely fixed -- I think it needs pcwalton's `memcpy` optimizations still (#103830) to get further -- but this seems to go much better than before. And the remaining `memcpy`s are just `transmute`-equivalent (`[T; N] -> ManuallyDrop<[T; N]>` and `[MaybeUninit<T>; N] -> [T; N]`), so hopefully those will be easier to remove with LLVM16 than the previous subobject copies 🤞
r? `@thomcc`
As a simple example, this test
```rust
pub fn long_integer_map(x: [u32; 64]) -> [u32; 64] {
x.map(|x| 13 * x + 7)
}
```
On nightly <https://rust.godbolt.org/z/xK7548TGj> takes `sub rsp, 808`
```llvm
start:
%array.i.i.i.i = alloca [64 x i32], align 4
%_3.sroa.5.i.i.i = alloca [65 x i32], align 4
%_5.i = alloca %"core::iter::adapters::map::Map<core::array::iter::IntoIter<u32, 64>, [closure@/app/example.rs:2:11: 2:14]>", align 8
```
(and yes, that's a 6**5**-element array `alloca` despite 6**4**-element input and output)
But with this PR it's only `sub rsp, 520`
```llvm
start:
%array.i.i.i.i.i.i = alloca [64 x i32], align 4
%array1.i.i.i = alloca %"core::mem::manually_drop::ManuallyDrop<[u32; 64]>", align 4
```
Similarly, the loop it emits on nightly is scalar-only and horrifying
```nasm
.LBB0_1:
mov esi, 64
mov edi, 0
cmp rdx, 64
je .LBB0_3
lea rsi, [rdx + 1]
mov qword ptr [rsp + 784], rsi
mov r8d, dword ptr [rsp + 4*rdx + 528]
mov edi, 1
lea edx, [r8 + 2*r8]
lea r8d, [r8 + 4*rdx]
add r8d, 7
.LBB0_3:
test edi, edi
je .LBB0_11
mov dword ptr [rsp + 4*rcx + 272], r8d
cmp rsi, 64
jne .LBB0_6
xor r8d, r8d
mov edx, 64
test r8d, r8d
jne .LBB0_8
jmp .LBB0_11
.LBB0_6:
lea rdx, [rsi + 1]
mov qword ptr [rsp + 784], rdx
mov edi, dword ptr [rsp + 4*rsi + 528]
mov r8d, 1
lea esi, [rdi + 2*rdi]
lea edi, [rdi + 4*rsi]
add edi, 7
test r8d, r8d
je .LBB0_11
.LBB0_8:
mov dword ptr [rsp + 4*rcx + 276], edi
add rcx, 2
cmp rcx, 64
jne .LBB0_1
```
whereas with this PR it's unrolled and vectorized
```nasm
vpmulld ymm1, ymm0, ymmword ptr [rsp + 64]
vpaddd ymm1, ymm1, ymm2
vmovdqu ymmword ptr [rsp + 328], ymm1
vpmulld ymm1, ymm0, ymmword ptr [rsp + 96]
vpaddd ymm1, ymm1, ymm2
vmovdqu ymmword ptr [rsp + 360], ymm1
```
(though sadly still stack-to-stack)
fix UB in ancient test
This seems to go back all the way to the [original version of this test](b9aa9def85/src/test/run-pass/regions-mock-trans.rs) from ten years ago... ``@nikomatsakis`` trip down memory lane? ;)
Clearly deallocation is a form of mutation so doing it to a (pointer derived from a) shared reference cannot be legal. Let's use mutable references instead.
