stop using `ty::UnevaluatedConst` directly
best reviewed commit by commit.
simplifies #99798 because we now don't have to expand `ty::UnevaluatedConst` to `ty::Const`.
I also remember some other places where using `ty::UnevaluatedConst` directly was annoying and caused issues, though I don't quite remember what they were rn '^^
r? `@oli-obk` cc `@JulianKnodt`
Get rid of native_library projection queries
They don't seem particularly useful as I don't expect native libraries to change frequently.
Maybe they do provide significant value of keeping incremental compilation green though, I'm not sure.
Introduce deduced parameter attributes, and use them for deducing `readonly` on indirect immutable freeze by-value function parameters.
Introduce deduced parameter attributes, and use them for deducing `readonly` on
indirect immutable freeze by-value function parameters.
Right now, `rustc` only examines function signatures and the platform ABI when
determining the LLVM attributes to apply to parameters. This results in missed
optimizations, because there are some attributes that can be determined via
analysis of the MIR making up the function body. In particular, `readonly`
could be applied to most indirectly-passed by-value function arguments
(specifically, those that are freeze and are observed not to be mutated), but
it currently is not.
This patch introduces the machinery that allows `rustc` to determine those
attributes. It consists of a query, `deduced_param_attrs`, that, when
evaluated, analyzes the MIR of the function to determine supplementary
attributes. The results of this query for each function are written into the
crate metadata so that the deduced parameter attributes can be applied to
cross-crate functions. In this patch, we simply check the parameter for
mutations to determine whether the `readonly` attribute should be applied to
parameters that are indirect immutable freeze by-value. More attributes could
conceivably be deduced in the future: `nocapture` and `noalias` come to mind.
Adding `readonly` to indirect function parameters where applicable enables some
potential optimizations in LLVM that are discussed in [issue 103103] and [PR
103070] around avoiding stack-to-stack memory copies that appear in functions
like `core::fmt::Write::write_fmt` and `core::panicking::assert_failed`. These
functions pass a large structure unchanged by value to a subfunction that also
doesn't mutate it. Since the structure in this case is passed as an indirect
parameter, it's a pointer from LLVM's perspective. As a result, the
intermediate copy of the structure that our codegen emits could be optimized
away by LLVM's MemCpyOptimizer if it knew that the pointer is `readonly
nocapture noalias` in both the caller and callee. We already pass `nocapture
noalias`, but we're missing `readonly`, as we can't determine whether a
by-value parameter is mutated by examining the signature in Rust. I didn't have
much success with having LLVM infer the `readonly` attribute, even with fat
LTO; it seems that deducing it at the MIR level is necessary.
No large benefits should be expected from this optimization *now*; LLVM needs
some changes (discussed in [PR 103070]) to more aggressively use the `noalias
nocapture readonly` combination in its alias analysis. I have some LLVM patches
for these optimizations and have had them looked over. With all the patches
applied locally, I enabled LLVM to remove all the `memcpy`s from the following
code:
```rust
fn main() {
println!("Hello {}", 3);
}
```
which is a significant codegen improvement over the status quo. I expect that if this optimization kicks in in multiple places even for such a simple program, then it will apply to Rust code all over the place.
[issue 103103]: https://github.com/rust-lang/rust/issues/103103
[PR 103070]: https://github.com/rust-lang/rust/pull/103070
Rollup of 9 pull requests
Successful merges:
- #102635 (make `order_dependent_trait_objects` show up in future-breakage reports)
- #103335 (Replaced wrong test with the correct mcve)
- #103339 (Fix some typos)
- #103340 (WinConsole::new is not actually fallible)
- #103341 (Add test for issue 97607)
- #103351 (Require Drop impls to have the same constness on its bounds as the bounds on the struct have)
- #103359 (Remove incorrect comment in `Vec::drain`)
- #103364 (rustdoc: clean up rustdoc-toggle CSS)
- #103370 (rustdoc: remove unused CSS `.out-of-band { font-weight: normal }`)
Failed merges:
r? `@ghost`
`@rustbot` modify labels: rollup
rustdoc: remove unused CSS `.out-of-band { font-weight: normal }`
This CSS was added in 083c3952e0 to normalize the appearance of out-of-band elements that were nested directly below headers.
Now, the only use of `out-of-band` is in the main page header, and it is nested below a wrapper, not the `<h1>` itself.
Remove incorrect comment in `Vec::drain`
r? ``@scottmcm``
Turns out this comment wasn't correct for 6 years, since #34951, which switched from using `slice::IterMut` into using `slice::Iter`.
Add test for issue 97607
Fixes#97607
r? ``@compiler-errors``
Not sure which UI test dir to put this under, kindly let me know of a better dir if necessary and I will change it. Thanks.
Replaced wrong test with the correct mcve
Closes#89008.
The old test was wrong and the compiler was [correctly raising an error](https://github.com/rust-lang/rust/issues/89008#issuecomment-1285128060). The bug in the issue was resolved at some point but due to the wrong test the issue was never closed.
This pr replaces that test with the correct MCVE (made by ``@jackh726).``
The error raised by the bug changed between when the bug was posted (2021-09-08) and when the MCVE [was posted](https://github.com/rust-lang/rust/issues/89008#issuecomment-950110735) (2021-10-23).
I ran them both through `nightly-2021-09-08` and they produce identical error messages. They also produce identical but different from before error messages when ran through `nightly-2021-10-23`.
<details>
<summary>Error message with <code>nightly-2021-09-08</code></summary>
The code with the original bug report:
```
error[E0277]: the size for values of type `Repr` cannot be known at compilation time
--> src/main.rs:23:43
|
23 | fn line_stream<'a, Repr>(&'a self) -> Self::LineStreamFut<'a, Repr> {
| ---- ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^ doesn't have a size known at compile-time
| |
| this type parameter needs to be `std::marker::Sized`
For more information about this error, try `rustc --explain E0277`.
error: could not compile `test-234234` due to previous error
```
MVCE:
```
error[E0277]: the size for values of type `Repr` cannot be known at compilation time
--> src/main.rs:30:43
|
30 | fn line_stream<'a, Repr>(&'a self) -> Self::LineStreamFut<'a, Repr> {
| ---- ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^ doesn't have a size known at compile-time
| |
| this type parameter needs to be `std::marker::Sized`
For more information about this error, try `rustc --explain E0277`.
error: could not compile `test-234234` due to previous error
```
</details>
<details>
<summary>Error message with <code>nightly-2021-10-23</code></summary>
The code with the original bug report:
```
error[E0271]: type mismatch resolving `<impl futures::Future as futures::Future>::Output == impl futures::Stream`
--> src/main.rs:23:43
|
19 | type LineStream<'a, Repr> = impl Stream<Item = Repr>;
| ------------------------ the expected opaque type
...
23 | fn line_stream<'a, Repr>(&'a self) -> Self::LineStreamFut<'a, Repr> {
| ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^ expected opaque type, found struct `futures::stream::Empty`
|
= note: expected opaque type `impl futures::Stream`
found struct `futures::stream::Empty<_>`
error: could not find defining uses
--> src/main.rs:19:33
|
19 | type LineStream<'a, Repr> = impl Stream<Item = Repr>;
| ^^^^^^^^^^^^^^^^^^^^^^^^
For more information about this error, try `rustc --explain E0271`.
error: could not compile `test-234234` due to 2 previous errors
```
MCVE:
```
error[E0271]: type mismatch resolving `<impl Future as Future>::Output == impl Stream`
--> src/main.rs:30:43
|
28 | type LineStream<'a, Repr> = impl Stream<Item = Repr>;
| ------------------------ the expected opaque type
29 | type LineStreamFut<'a, Repr> = impl Future<Output = Self::LineStream<'a, Repr>>;
30 | fn line_stream<'a, Repr>(&'a self) -> Self::LineStreamFut<'a, Repr> {
| ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^ expected opaque type, found struct `Empty`
|
= note: expected opaque type `impl Stream`
found struct `Empty<_>`
error: could not find defining uses
--> src/main.rs:28:33
|
28 | type LineStream<'a, Repr> = impl Stream<Item = Repr>;
| ^^^^^^^^^^^^^^^^^^^^^^^^
For more information about this error, try `rustc --explain E0271`.
error: could not compile `test-234234` due to 2 previous errors
```
</details>
make `order_dependent_trait_objects` show up in future-breakage reports
tried to change it to a hard error in #102474 but breaking the more than 1000 dependents of `traitobject` doesn't feel great 😅
This lint has existed since more than 3 years now and the way this is currently implemented is buggy and will break with #102472. imo we should upgrade it to also report for dependencies and maybe also backport this to beta. Then after maybe 2-3 stable versions I would like to finally convert this lint to a hard error.
This CSS was added in 083c3952e0 to
normalize the appearance of out-of-band elements that were nested directly
below headers.
Now, the only use of `out-of-band` is in the main page header, and it is
nested below a wrapper, not the `<h1>` itself.
Add default trait implementations for "c-unwind" ABI function pointers
Following up on #92964, only add default trait implementations for the `c-unwind` family of function pointers. The previous attempt in #92964 added trait implementations for many more ABIs and ran into concerns regarding the increase in size of the libcore rlib.
An attempt to abstract away function pointer types behind a unified trait to reduce the duplication of trait impls is being discussed in #99531 but this change looks to be blocked on a lang MCP.
Following `@RalfJung's` suggestion in https://github.com/rust-lang/rust/pull/99531#issuecomment-1233440142, this commit is another cut at #92964 but it _only_ adds the impls for `extern "C-unwind" fn` and `unsafe extern "C-unwind" fn`.
I am interested in landing this patch to unblock the stabilization of the `c_unwind` feature.
RFC: https://github.com/rust-lang/rfcs/pull/2945
Tracking Issue: https://github.com/rust-lang/rust/issues/74990
Change process spawning to inherit the parent's signal mask by default
Previously, the signal mask was always reset when a child process is
started. This breaks tools like `nohup` which expect `SIGHUP` to be
blocked for all transitive processes.
With this change, the default behavior changes to inherit the signal mask.
This also changes the signal disposition for `SIGPIPE` to only be changed if the `#[unix_sigpipe]` attribute isn't set.
Remove more attributes from metadata
A lot of the attributes that are currently stored in the metadata aren't used at all. The biggest metadata usage comes from the doc attributes currently but they are needed by rustdoc so we only removed the ones that cannot be used in downstream crates (doc comments on private items).
r? `@ghost`
Rollup of 6 pull requests
Successful merges:
- #102287 (Elaborate supertrait bounds when triggering `unused_must_use` on `impl Trait`)
- #102922 (Filtering spans when emitting json)
- #103051 (translation: doc comments with derives, subdiagnostic-less enum variants, more derive use)
- #103111 (Account for hygiene in typo suggestions, and use them to point to shadowed names)
- #103260 (Fixup a few tests needing asm support)
- #103321 (rustdoc: improve appearance of source page navigation bar)
Failed merges:
- #103209 (Diagnostic derives: allow specifying multiple alternative suggestions)
r? `@ghost`
`@rustbot` modify labels: rollup
translation: doc comments with derives, subdiagnostic-less enum variants, more derive use
- Adds support for `doc` attributes in the diagnostic derives so that documentation comments don't result in the derive failing.
- Adds support for enum variants in the subdiagnostic derive to not actually correspond to an addition to a diagnostic.
- Made use of the derive in more places in the `rustc_ast_lowering`, `rustc_ast_passes`, `rustc_lint`, `rustc_session`, `rustc_infer` - taking advantage of recent additions like eager subdiagnostics, multispan suggestions, etc.
cc #100717
Elaborate supertrait bounds when triggering `unused_must_use` on `impl Trait`
Given `impl Trait`, if one of its supertraits has a `#[must_use]`, then trigger the lint. This means that, for example, `-> impl ExactSizeIterator` also triggers the `must_use` on `trait Iterator`, which fixes#102183.
This might need `@rust-lang/lang` sign-off, since it changes the behavior of the lint, so cc'ing them.
move hir typeck into separate crate
second part https://github.com/rust-lang/compiler-team/issues/529
I avoided pretty much anything that wasn't just a simple move + path adjustment. Left fixmes for methods which are at an odd place
r? `@compiler-errors`
indirect immutable freeze by-value function parameters.
Right now, `rustc` only examines function signatures and the platform ABI when
determining the LLVM attributes to apply to parameters. This results in missed
optimizations, because there are some attributes that can be determined via
analysis of the MIR making up the function body. In particular, `readonly`
could be applied to most indirectly-passed by-value function arguments
(specifically, those that are freeze and are observed not to be mutated), but
it currently is not.
This patch introduces the machinery that allows `rustc` to determine those
attributes. It consists of a query, `deduced_param_attrs`, that, when
evaluated, analyzes the MIR of the function to determine supplementary
attributes. The results of this query for each function are written into the
crate metadata so that the deduced parameter attributes can be applied to
cross-crate functions. In this patch, we simply check the parameter for
mutations to determine whether the `readonly` attribute should be applied to
parameters that are indirect immutable freeze by-value. More attributes could
conceivably be deduced in the future: `nocapture` and `noalias` come to mind.
Adding `readonly` to indirect function parameters where applicable enables some
potential optimizations in LLVM that are discussed in [issue 103103] and [PR
103070] around avoiding stack-to-stack memory copies that appear in functions
like `core::fmt::Write::write_fmt` and `core::panicking::assert_failed`. These
functions pass a large structure unchanged by value to a subfunction that also
doesn't mutate it. Since the structure in this case is passed as an indirect
parameter, it's a pointer from LLVM's perspective. As a result, the
intermediate copy of the structure that our codegen emits could be optimized
away by LLVM's MemCpyOptimizer if it knew that the pointer is `readonly
nocapture noalias` in both the caller and callee. We already pass `nocapture
noalias`, but we're missing `readonly`, as we can't determine whether a
by-value parameter is mutated by examining the signature in Rust. I didn't have
much success with having LLVM infer the `readonly` attribute, even with fat
LTO; it seems that deducing it at the MIR level is necessary.
No large benefits should be expected from this optimization *now*; LLVM needs
some changes (discussed in [PR 103070]) to more aggressively use the `noalias
nocapture readonly` combination in its alias analysis. I have some LLVM patches
for these optimizations and have had them looked over. With all the patches
applied locally, I enabled LLVM to remove all the `memcpy`s from the following
code:
```rust
fn main() {
println!("Hello {}", 3);
}
```
which is a significant codegen improvement over the status quo. I expect that
if this optimization kicks in in multiple places even for such a simple
program, then it will apply to Rust code all over the place.
[issue 103103]: https://github.com/rust-lang/rust/issues/103103
[PR 103070]: https://github.com/rust-lang/rust/pull/103070
Mark `std::os::wasi::io::AsFd` etc. as stable.
io_safety was stabilized in Rust 1.63, so mark the io_safety exports in `std::os::wasi::io` as stable.
Fixes#103306.
Previously, the signal mask is always reset when a child process is
started. This breaks tools like `nohup` which expect `SIGHUP` to be
blocked.
With this change, the default behavior changes to inherit the signal mask.
This also changes the signal disposition for `SIGPIPE` to only be
changed if the `#[unix_sigpipe]` attribute isn't set.
Rollup of 9 pull requests
Successful merges:
- #103221 (Fix `SelfVisitor::is_self_ty` ICE)
- #103230 (Clarify startup)
- #103281 (Adjust `transmute{,_copy}` to be clearer about which of `T` and `U` is input vs output)
- #103288 (Fixed docs typo in `library/std/src/time.rs`)
- #103296 (+/- shortcut now only expand/collapse, not both)
- #103297 (fix typo)
- #103313 (Don't label `src/test` tests as `A-testsuite`)
- #103315 (interpret: remove an incorrect assertion)
- #103319 (Improve "`~const` is not allowed here" message)
Failed merges:
r? `@ghost`
`@rustbot` modify labels: rollup
interpret: remove an incorrect assertion
This fixes an ICE in Miri, [reported](https://rust-lang.zulipchat.com/#narrow/stream/269128-miri/topic/SwitchInt.20with.20no.20targets.3F) by `@saethlin.` The faulty assertion was introduced by 432535da2b, when a previously correct assertion checking that the `otherwise` target exists got replaced by this assertion checking that at least one more target beyond `otherwise` exists.
Sadly we don't have a small reproducer so I don't think we can easily add a testcase.
