Do not suggest trivially false const predicates
Pass through constness to `predicate_can_apply` and don't suggest other impls if it's satisfied but not const.
Fixes#103267
Introduce `subst_iter` and `subst_iter_copied` on `EarlyBinder`
Makes working with bounds lists a bit easier, which I seem to do a lot.
Specifically, means that we don't need to do `.transpose_iter().map(|(pred, _)| *pred)` every time we want to iterate through an `EarlyBinder<&'tcx [(Predicate, Span)]>` (and even then, still have to call `subst` later), which was a very awkward idiom imo.
Rust's niche handling allows for wrapping valid ranges with end < start;
for instance, a valid range with start=43 and end=41 means a niche of
42. Most places in the compiler handle this correctly, but
ty_find_init_error assumed that `lo > 0` means the type cannot contain a
zero.
Fix it to handle wrapping ranges.
Add a test to cover this case.
Allow semicolon after closure within parentheses in macros
#88546 added some parsing logic that if we're parsing a closure, and we're within parentheses, and a semicolon follows, then we must be parsing something erroneous like: `f(|| a; b)`, so it replaces the closure body with an error expression. However, it's valid to parse those tokens if we're within a macro, as in #103222.
This is a bit unsatisfying fix. Is there a more robust way of checking that we're within a macro?
I would also be open to removing this "_It is likely that the closure body is a block but where the braces have been removed_" check altogether at the expense of more verbose errors, since it seems very suspicious in the first place...
Fixes#103222.
Slightly tweak comments wrt `lint_overflowing_range_endpoint`
From the review: https://github.com/rust-lang/rust/pull/101986#discussion_r975610611
It _seemed_ that the lint was not emitted when the `if` check failed, but _actually_ this happens already in a special case and the lint is emitted outside of this function, if this function doesn't. I've cleared up the code/comments a bit, so it's more obvious :)
r? ```@estebank```
Remove byte swap of valtree hash on big endian
This addresses problem reported in #103183. The code was originally introduced in e14b34c386. (see https://github.com/rust-lang/rust/pull/96591)
On big-endian environment, this operation sequence actually put the other half from 128-bit result, thus we got different hash result on LE and BE.
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.
The latest version of `rental` (v0.5.6) contains a fix that allows it to
compile without relying on the pretty-print back-compat hack.
Hopefully, there are no longer any crates relying on the affected
versions of the (much less popular) `procedural-masquerade` crate. This
should allow us to target the pretty-print back-compat hack specifically
to older versions of `rental`, and specifically mention upgrading to
`rental` v0.5.6 in the lint message.
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
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.
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
