Add new lint for undropped ManuallyDrop values
Adds a new lint for the following code:
```rust
struct S;
impl Drop for S {
fn drop(&mut self) {
println!("drip drop");
}
}
fn main() {
// This will not drop the `S`!!!
drop(std::mem::ManuallyDrop::new(S));
unsafe {
// This will.
std::mem::ManuallyDrop::drop(&mut std::mem::ManuallyDrop::new(S));
}
}
```
The inner value of a `ManuallyDrop` will not be dropped unless the proper, unsafe drop function is called on it. This lint makes sure that a user does not accidently use the wrong function and forget to drop a `ManuallyDrop` value.
Fixes#5581.
---
*Please keep the line below*
changelog: none
perf: buffer SipHasher128
This is an attempt to improve Siphasher128 performance by buffering input. Although it reduces instruction count, I'm not confident the effect on wall times, or lack-thereof, is worth the change.
---
Additional notes not reflected in source comments:
* Implementation choices were guided by a combination of results from rustc-perf and micro-benchmarks, mostly the former.
* ~~I tried a couple of different struct layouts that might be more cache friendly with no obvious effect.~~ Update: a particular struct layout was chosen, but it's not critical to performance. See comments in source and discussion below.
* I suspect that buffering would be important to a SIMD-accelerated algorithm, but from what I've read and my own tests, SipHash does not seem very amenable to SIMD acceleration, at least by SSE.
Add lint for holding RefCell Ref across an await
Fixes#6008
This introduces the lint await_holding_refcell_ref. For async functions, we iterate
over all types in generator_interior_types and look for `core::cell::Ref` or `core::cell::RefMut`. If we find one then we emit a lint.
Heavily cribs from: https://github.com/rust-lang/rust-clippy/pull/5439
changelog: introduce the await_holding_refcell_ref lint
fix def collector for impl trait
fixes#77329
We now consistently make `impl Trait` a hir owner, requiring some special casing for synthetic generic params.
r? `@eddyb`
Upgrade to measureme 9.0.0
I believe I did this correctly but there's still a reference to `measureme@0.7.1` coming from `rustc-ap-rustc_data_structures` and I'm not sure how to resolve that.
r? `@Mark-Simulacrum`
We'll also need to deploy the new version of the tools on perf.rlo.
stop promoting union field accesses in 'const'
Turns out that promotion of union field accesses is the only difference between "promotion in `const`/`static` bodies" and "explicit promotion". So if we can remove this, we have finally achieved what I thought to already be the case -- that the bodies of `const`/`static` initializers behave the same as explicit promotion contexts.
The reason we do not want to promote union field accesses is that they can introduce UB, i.e., they can go wrong. We want to [minimize the ways promoteds can fail to evaluate](https://github.com/rust-lang/const-eval/issues/53). Also this change makes things more consistent overall, removing a special case that was added without much consideration (as far as I can tell).
Cc `@rust-lang/wg-const-eval`
Lint unnecessary int-to-int and float-to-float casts
This is an implementation of a lint that detects unnecessary casts of number literals, as discussed here:
https://github.com/rust-lang/rust-clippy/issues/6116
---
changelog: lint unnecessary as-casts of literals when they could be written using literal syntax.
Add large_types_passed_by_value lint
Creates a new lint that checks for large function parameters passed by value. ~Types that are Copy were ignored, because I understand they are explicitly marked as being cheap (or just acceptable) to copy. Arrays were excluded from that restriction because they are always Copy, independently of the size, if the elements are Copy.~ Only Copy types are considered, because if a type is not Copy it cannot be dereferenced, as pointed out by `@ebroto,` and that would require analyzing the whole function body to check if the argument is moved somewhere else. `self` and `mut` parameters are also skipped.
I refactored `trivially_copy_pass_by_ref` and the new lint into a new `pass_by_ref_or_value` module, since both share most of their implementations, as was pointed out to me in #4499.
~Some questions that remain:~
~1. Should `self` be disregarded for this lint?~
~2. Should we special case types like Vec and String when suggesting changes? (to slices and &str)~
~3. What should be the default size limit?~
~4. Are there any special cases I'm missing?~
I ask the maintainers to add the `hacktoberfest-accepted` label if this PR is decent, even if there are some minor details to work out, but I do intend to stick around and finish the job.
Fixes#4499
changelog: Add new lint [`large_types_passed_by_value`]
Rollup of 12 pull requests
Successful merges:
- #75115 (`#[deny(unsafe_op_in_unsafe_fn)]` in sys/cloudabi)
- #76614 (change the order of type arguments on ControlFlow)
- #77610 (revise Hermit's mutex interface to support the behaviour of StaticMutex)
- #77830 (Simplify query proc-macros)
- #77930 (Do not ICE with TraitPredicates containing [type error])
- #78069 (Fix const core::panic!(non_literal_str).)
- #78072 (Cleanup constant matching in exhaustiveness checking)
- #78119 (Throw core::panic!("message") as &str instead of String.)
- #78191 (Introduce a temporary for discriminant value in MatchBranchSimplification)
- #78272 (const_evaluatable_checked: deal with unused nodes + div)
- #78318 (TyCtxt: generate single impl block with `slice_interners` macro)
- #78327 (resolve: Relax macro resolution consistency check to account for any errors)
Failed merges:
r? `@ghost`
resolve: Relax macro resolution consistency check to account for any errors
The check was previously omitted only when ambiguity errors or `Res::Err` were encountered, but the "macro-expanded `extern crate` items cannot shadow..." error (at least) can cause same inconsistencies as well.
Fixes https://github.com/rust-lang/rust/issues/78325
Introduce a temporary for discriminant value in MatchBranchSimplification
The optimization introduces additional uses of the discriminant operand, but
does not ensure that it is still valid to evaluate it or that it still
evaluates to the same value.
Evaluate it once at original position, and store the result in a new temporary.
Follow up on #78151. The optimization remains disabled by default.
Closes#78239.
Throw core::panic!("message") as &str instead of String.
This makes `core::panic!("message")` consistent with `std::panic!("message")`, which throws a `&str` and not a `String`.
This also makes any other panics from `core::panicking::panic` result in a `&str` rather than a `String`, which includes compiler-generated panics such as the panics generated for `mem::zeroed()`.
---
Demonstration:
```rust
use std::panic;
use std::any::Any;
fn main() {
panic::set_hook(Box::new(|panic_info| check(panic_info.payload())));
check(&*panic::catch_unwind(|| core::panic!("core")).unwrap_err());
check(&*panic::catch_unwind(|| std::panic!("std")).unwrap_err());
}
fn check(msg: &(dyn Any + Send)) {
if let Some(s) = msg.downcast_ref::<String>() {
println!("Got a String: {:?}", s);
} else if let Some(s) = msg.downcast_ref::<&str>() {
println!("Got a &str: {:?}", s);
}
}
```
Before:
```
Got a String: "core"
Got a String: "core"
Got a &str: "std"
Got a &str: "std"
```
After:
```
Got a &str: "core"
Got a &str: "core"
Got a &str: "std"
Got a &str: "std"
```
Cleanup constant matching in exhaustiveness checking
This supercedes https://github.com/rust-lang/rust/pull/77390. I made the `Opaque` constructor work.
I have opened two issues https://github.com/rust-lang/rust/issues/78071 and https://github.com/rust-lang/rust/issues/78057 from the discussion we had on the previous PR. They are not regressions nor directly related to the current PR so I thought we'd deal with them separately.
I left a FIXME somewhere because I didn't know how to compare string constants for equality. There might even be some unicode things that need to happen there. In the meantime I preserved previous behavior.
EDIT: I accidentally fixed#78071
Fix const core::panic!(non_literal_str).
Invocations of `core::panic!(x)` where `x` is not a string literal expand to `panic!("{}", x)`, which is not understood by the const panic logic right now. This adds `panic_str` as a lang item, and modifies the const eval implementation to hook into this item as well.
This fixes the issue mentioned here: https://github.com/rust-lang/rust/issues/51999#issuecomment-687604248
r? `@RalfJung`
`@rustbot` modify labels: +A-const-eval
Simplify query proc-macros
The query code generation is split between proc-macros and regular macros in `rustc_middle::ty::query`.
This PR removes unused capabilities of the proc-macros, and tend to use regular macros for the logic.
revise Hermit's mutex interface to support the behaviour of StaticMutex
rust-lang/rust#77147 simplifies things by splitting this Mutex type into two types matching the two use cases: StaticMutex and MovableMutex. To support the new behavior of StaticMutex, we move part of the mutex implementation into libstd.
The interface to the OS changed. Consequently, I removed a few functions, which aren't longer needed.
change the order of type arguments on ControlFlow
This allows ControlFlow<BreakType> which is much more ergonomic for common iterator combinator use cases.
Addresses one component of #75744
Unconditionally capture tokens for attributes.
This allows us to avoid synthesizing tokens in `prepend_attr`, since we
have the original tokens available.
We still need to synthesize tokens when expanding `cfg_attr`,
but this is an unavoidable consequence of the syntax of `cfg_attr` -
the user does not supply the `#` and `[]` tokens that a `cfg_attr`
expands to.
This is based on PR https://github.com/rust-lang/rust/pull/77250 - this PR exposes a bug in the current `collect_tokens` implementation, which is fixed by the rewrite.
Fixes#75982
The direct parent of a module may not be a module
(e.g. `const _: () = { #[path = "foo.rs"] mod foo; };`).
To find the parent of a module for purposes of resolution, we need to
walk up the tree until we hit a module or a crate root.
Refactor trivially_copy_pass_by_ref and the new lint into pass_by_ref_or_value module
Update stderr of conf_unknown_key test
Rename lint to large_types_passed_by_value
Increase `pass_by_value_size_limit` default value to 256
Improve rules for `large_types_passed_by_value`
Improve tests for `large_types_passed_by_value`
Improve documentation for `large_types_passed_by_value`
Make minor corrections to pass_by_ref_or_value.rs suggested by clippy itself
Fix `large_types_passed_by_value` example and improve docs
pass_by_ref_or_value: Tweak check for mut annotation in params
large_types_passed_by_value: add tests for pub trait, trait impl and inline attributes
When the 'early' and 'late' visitors visit an attribute target, they
activate any lint attributes (e.g. `#[allow]`) that apply to it.
This can affect warnings emitted on sibiling attributes. For example,
the following code does not produce an `unused_attributes` for
`#[inline]`, since the sibiling `#[allow(unused_attributes)]` suppressed
the warning.
```rust
trait Foo {
#[allow(unused_attributes)] #[inline] fn first();
#[inline] #[allow(unused_attributes)] fn second();
}
```
However, we do not do this for statements - instead, the lint attributes
only become active when we visit the struct nested inside `StmtKind`
(e.g. `Item`).
Currently, this is difficult to observe due to another issue - the
`HasAttrs` impl for `StmtKind` ignores attributes for `StmtKind::Item`.
As a result, the `unused_doc_comments` lint will never see attributes on
item statements.
This commit makes two interrelated fixes to the handling of inert
(non-proc-macro) attributes on statements:
* The `HasAttr` impl for `StmtKind` now returns attributes for
`StmtKind::Item`, treating it just like every other `StmtKind`
variant. The only place relying on the old behavior was macro
which has been updated to explicitly ignore attributes on item
statements. This allows the `unused_doc_comments` lint to fire for
item statements.
* The `early` and `late` lint visitors now activate lint attributes when
invoking the callback for `Stmt`. This ensures that a lint
attribute (e.g. `#[allow(unused_doc_comments)]`) can be applied to
sibiling attributes on an item statement.
For now, the `unused_doc_comments` lint is explicitly disabled on item
statements, which preserves the current behavior. The exact locatiosn
where this lint should fire are being discussed in PR #78306
When the 'early' and 'late' visitors visit an attribute target, they
activate any lint attributes (e.g. `#[allow]`) that apply to it.
This can affect warnings emitted on sibiling attributes. For example,
the following code does not produce an `unused_attributes` for
`#[inline]`, since the sibiling `#[allow(unused_attributes)]` suppressed
the warning.
```rust
trait Foo {
#[allow(unused_attributes)] #[inline] fn first();
#[inline] #[allow(unused_attributes)] fn second();
}
```
However, we do not do this for statements - instead, the lint attributes
only become active when we visit the struct nested inside `StmtKind`
(e.g. `Item`).
Currently, this is difficult to observe due to another issue - the
`HasAttrs` impl for `StmtKind` ignores attributes for `StmtKind::Item`.
As a result, the `unused_doc_comments` lint will never see attributes on
item statements.
This commit makes two interrelated fixes to the handling of inert
(non-proc-macro) attributes on statements:
* The `HasAttr` impl for `StmtKind` now returns attributes for
`StmtKind::Item`, treating it just like every other `StmtKind`
variant. The only place relying on the old behavior was macro
which has been updated to explicitly ignore attributes on item
statements. This allows the `unused_doc_comments` lint to fire for
item statements.
* The `early` and `late` lint visitors now activate lint attributes when
invoking the callback for `Stmt`. This ensures that a lint
attribute (e.g. `#[allow(unused_doc_comments)]`) can be applied to
sibiling attributes on an item statement.
For now, the `unused_doc_comments` lint is explicitly disabled on item
statements, which preserves the current behavior. The exact locatiosn
where this lint should fire are being discussed in PR #78306
If there are two lists of different sizes,
iterating over the smaller list and then
looking up in the larger list is cheaper
than vice versa, because lookups scale
sublinearly.
