| Age | Commit message (Collapse) | Author | Lines |
|---|
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```
error[E0716]: temporary value dropped while borrowed
--> $DIR/multiple-sources-for-outlives-requirement.rs:5:38
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LL | fn foo<'b>() {
| -- lifetime `'b` defined here
LL | outlives_indir::<'_, 'b, _>(&mut 1u32);
| ---------------------------------^^^^-- temporary value is freed at the end of this statement
| | |
| | creates a temporary value which is freed while still in use
| argument requires that borrow lasts for `'b`
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note: requirements that the value outlives `'b` introduced here
--> $DIR/multiple-sources-for-outlives-requirement.rs:1:23
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LL | fn outlives_indir<'a: 'b, 'b, T: 'a>(_x: T) {}
| ^^ ^^
```
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```
error[E0597]: `c` does not live long enough
--> $DIR/without-precise-captures-we-are-powerless.rs:19:20
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LL | fn simple<'a>(x: &'a i32) {
| -- lifetime `'a` defined here
...
LL | let c = async move || { println!("{}", *x); };
| - binding `c` declared here
LL | outlives::<'a>(c());
| ---------------^---
| | |
| | borrowed value does not live long enough
| argument requires that `c` is borrowed for `'a`
LL | outlives::<'a>(call_once(c));
LL | }
| - `c` dropped here while still borrowed
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note: requirement that `c` is borrowed for `'a` introduced here
--> $DIR/without-precise-captures-we-are-powerless.rs:7:33
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LL | fn outlives<'a>(_: impl Sized + 'a) {}
| ^^
```
When encountering a `ConstraintCategory::Predicate` in a funtion call, point at the `Span` for that `Predicate` to explain where the lifetime obligation originates from.
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```
error[E0621]: explicit lifetime required in the type of `x`
--> $DIR/42701_one_named_and_one_anonymous.rs:10:9
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LL | &*x
| ^^^ lifetime `'a` required
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help: add explicit lifetime `'a` to the type of `x`
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LL | fn foo2<'a>(a: &'a Foo, x: &'a i32) -> &'a i32 {
| ++
```
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r=traviscross,jieyouxu
Add a new `mismatched-lifetime-syntaxes` lint
The lang-team [discussed this](https://hackmd.io/nf4ZUYd7Rp6rq-1svJZSaQ) and I attempted to [summarize](https://github.com/rust-lang/rust/pull/120808#issuecomment-2701863833) their decision. The summary-of-the-summary is:
- Using two different kinds of syntax for elided lifetimes is confusing. In rare cases, it may even [lead to unsound code](https://github.com/rust-lang/rust/issues/48686)! Some examples:
```rust
// Lint will warn about these
fn(v: ContainsLifetime) -> ContainsLifetime<'_>;
fn(&'static u8) -> &u8;
```
- Matching up references with no lifetime syntax, references with anonymous lifetime syntax, and paths with anonymous lifetime syntax is an exception to the simplest possible rule:
```rust
// Lint will not warn about these
fn(&u8) -> &'_ u8;
fn(&'_ u8) -> &u8;
fn(&u8) -> ContainsLifetime<'_>;
```
- Having a lint for consistent syntax of elided lifetimes will make the [future goal](https://github.com/rust-lang/rust/issues/91639) of warning-by-default for paths participating in elision much simpler.
---
This new lint attempts to accomplish the goal of enforcing consistent syntax. In the process, it supersedes and replaces the existing `elided-named-lifetimes` lint, which means it starts out life as warn-by-default.
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when possible.
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Signed-off-by: xizheyin <xizheyin@smail.nju.edu.cn>
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```
error[E0610]: `{integer}` is a primitive type and therefore doesn't have fields
--> $DIR/attempted-access-non-fatal.rs:7:15
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LL | let _ = 2.l;
| ^
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help: if intended to be a floating point literal, consider adding a `0` after the period and a `f64` suffix
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LL - let _ = 2.l;
LL + let _ = 2.0f64;
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```
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for now, only builtin `Sized` impls are tracked as being `Trivial`
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`best_blame_constraint`: Blame better constraints when the region graph has cycles from invariance or `'static`
This fixes #132749 by changing which constraint is blamed for region errors in several cases. `best_blame_constraint` had a heuristic that tried to pinpoint the constraint causing an error by filtering out any constraints where the outliving region is unified with the ultimate target region being outlived. However, it used the SCCs of the region graph to do this, which is unreliable; in particular, if the target region is `'static`, or if there are cycles from the presence of invariant types, it was skipping over the constraints it should be blaming. As is the case in that issue, this could lead to confusing diagnostics. The simplest fix seems to work decently, judging by test stderr: this makes `best_blame_constraint` no longer filter constraints by their outliving region's SCC.
There are admittedly some quirks in the test output. In many cases, subdiagnostics that depend on the particular constraint being blamed have either started or stopped being emitted. After starting at this for quite a while, I think anything too fickle about whether it outputs based on the particular constraint being blamed should instead be looking at the constraint path as a whole, similar to what's done for [the placeholder-from-predicate note](https://github.com/rust-lang/rust/compare/master...dianne:rust:better-blame-constraints-for-static#diff-3c0de6462469af483c9ecdf2c4b00cb26192218ef2d5c62a0fde75107a74caaeR506).
Very many tests involving invariant types gained a note pointing out the types' invariance, but in a few cases it was lost. A particularly illustrative example is [tests/ui/lifetimes/copy_modulo_regions.stderr](https://github.com/rust-lang/rust/compare/master...dianne:rust:better-blame-constraints-for-static?expand=1#diff-96e1f8b29789b3c4ce2f77a5e0fba248829b97ef9d1ce39e7d2b4aa57b2cf4f0); I'd argue the new constraint is a better one to blame, but it lacks the variance diagnostic information that's elsewhere in the constraint path. If desired, I can try making that note check the whole path rather than just the blamed constraint.
The subdiagnostic [`BorrowExplanation::add_object_lifetime_default_note`](https://doc.rust-lang.org/nightly/nightly-rustc/rustc_borrowck/diagnostics/explain_borrow/enum.BorrowExplanation.html#method.add_object_lifetime_default_note) depends on a `Cast` being blamed, so [a special case](https://github.com/rust-lang/rust/pull/133858/commits/364ca7f99c12fb5220e6b568ac391979317ce878) was necessary to keep it from disappearing from tests specifically testing for it. However, see the FIXME comment in that commit; I think the special case should be removed once that subdiagnostic works properly, but it's nontrivial enough to warrant a separate PR. Incidentally, this removes the note from a test where it was being added erroneously: in [tests/ui/borrowck/two-phase-surprise-no-conflict.stderr](https://github.com/rust-lang/rust/compare/master...dianne:rust:better-blame-constraints-for-static?expand=1#diff-8cf085af8203677de6575a45458c9e6b03412a927df879412adec7e4f7ff5e14), the object lifetime is explicitly provided and it's not `'static`.
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The SCCs of the region graph are not a reliable heuristic to use for blaming an interesting
constraint for diagnostics. For region errors, if the outlived region is `'static`, or the involved
types are invariant in their lifetiems, there will be cycles in the constraint graph containing both
the target region and the most interesting constraints to blame. To get better diagnostics in these
cases, this commit removes that heuristic.
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Signed-off-by: fudancoder <fudancoder@icloud.com.>
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```
help: consider restricting type parameter `T` with traits `Copy` and `Trait`
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LL | fn duplicate_custom<T: Copy + Trait>(t: S<T>) -> (S<T>, S<T>) {
| ++++++++++++++
```
```
help: consider restricting type parameter `V` with trait `Copy`
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LL | fn index<'a, K, V: std::marker::Copy>(map: &'a HashMap<K, V>, k: K) -> &'a V {
| +++++++++++++++++++
```
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Done with
```bash
sd '//@ pretty-expanded.*\n' '' tests/ui/**/*.rs
```
and
```
sd '//@pretty-expanded.*\n' '' tests/ui/**/*.rs
```
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Given `trait Any: 'static` and a `struct` with a `Box<dyn Any + 'a>` field, point at the `'static` bound in `Any` to explain why `'a: 'static`.
```
error[E0478]: lifetime bound not satisfied
--> f202.rs:2:12
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2 | value: Box<dyn std::any::Any + 'a>,
| ^^^^^^^^^^^^^^^^^^^^^^^^^^^
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note: lifetime parameter instantiated with the lifetime `'a` as defined here
--> f202.rs:1:14
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1 | struct Hello<'a> {
| ^^
note: but lifetime parameter must outlive the static lifetime
--> /home/gh-estebank/rust/library/core/src/any.rs:113:16
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113 | pub trait Any: 'static {
| ^^^^^^^
```
Partially address #33652.
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This reverts commit 13314df21b0bb0cdd02c6760581d1b9f1052fa7e, reversing
changes made to 6e534c73c35f569492ed5fb5f349075d58ed8b7e.
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Account for `for` lifetimes when constructing closure to see if dereferencing the return value would be valid.
Fix #125634, fix #124563.
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Start pointing to where bindings were declared when they are captured in closures:
```
error[E0597]: `x` does not live long enough
--> $DIR/suggest-return-closure.rs:23:9
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LL | let x = String::new();
| - binding `x` declared here
...
LL | |c| {
| --- value captured here
LL | x.push(c);
| ^ borrowed value does not live long enough
...
LL | }
| -- borrow later used here
| |
| `x` dropped here while still borrowed
```
Suggest cloning in more cases involving closures:
```
error[E0507]: cannot move out of `foo` in pattern guard
--> $DIR/issue-27282-move-ref-mut-into-guard.rs:11:19
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LL | if { (|| { let mut bar = foo; bar.take() })(); false } => {},
| ^^ --- move occurs because `foo` has type `&mut Option<&i32>`, which does not implement the `Copy` trait
| |
| `foo` is moved here
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= note: variables bound in patterns cannot be moved from until after the end of the pattern guard
help: consider cloning the value if the performance cost is acceptable
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LL | if { (|| { let mut bar = foo.clone(); bar.take() })(); false } => {},
| ++++++++
```
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This reverts commit 65cd843ae06ad00123c131a431ed5304e4cd577a, reversing
changes made to d255c6a57c393db6221b1ff700daea478436f1cd.
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This improves parallel rustc parallelism by avoiding the bottleneck after each individual `par_body_owners` (because it needs to wait for queries to finish, so if there is one long running one, a lot of cores will be idle while waiting for the single query).
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detects redundant imports that can be eliminated.
for #117772 :
In order to facilitate review and modification, split the checking code and
removing redundant imports code into two PR.
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Co-authored-by: Adrian <adrian.iosdev@gmail.com>
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