| Age | Commit message (Collapse) | Author | Lines |
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Turn ProjectionElem::Subtype into CastKind::Subtype
I noticed that drop elaboration can't, in general, handle `ProjectionElem::SubType`. It creates a disjoint move path that overlaps with other move paths. (`Subslice` does too, and I'm working on a different PR to make that special case less fragile.) If its skipped and treated as the same move path as its parent then `MovePath.place` has multiple possible projections. (It would probably make sense to remove all `Subtype` projections for the canonical place but it doesn't make sense to have this special case for a problem that doesn't actually occur in real MIR.)
The only reason this doesn't break is that `Subtype` is always the sole projection of the local its applied to. For the same reason, it works fine as a `CastKind` so I figured that makes more sense than documenting and validating this hidden invariant.
cc rust-lang/rust#112651, rust-lang/rust#133258
r? Icnr (bc you've been the main person dealing with `Subtype` it looks like)
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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
|
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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Revise the extra `r: 'static` constraints added upon universe issues
to add an explanation, and use that explanation during constraint blame
search. This greatly simplifies the region inference logic, which
now does not need to reverse-engineer the event that caused a region
to outlive 'static.
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rework GAT borrowck limitation error
The old one depends on the `ConstraintCategory` of the constraint which meant we did not emit this note if we had to prove the higher ranked trait bound due to e.g. normalization.
This made it annoying brittle and caused MIR borrowck errors to be order dependent, fixes the issue in https://github.com/rust-lang/rust/pull/140737#discussion_r2259592651.
r? types cc ```@amandasystems```
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a move error
When encountering a move error involving a closure because the captured value isn't `Copy`, and the obligation comes from a bound on a type parameter that requires `Fn` or `FnMut`, we point at it and explain that an `FnOnce` wouldn't cause the move error.
```
error[E0507]: cannot move out of `foo`, a captured variable in an `Fn` closure
--> f111.rs:15:25
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14 | fn do_stuff(foo: Option<Foo>) {
| --- ----------- move occurs because `foo` has type `Option<Foo>`, which does not implement the `Copy` trait
| |
| captured outer variable
15 | require_fn_trait(|| async {
| -- ^^^^^ `foo` is moved here
| |
| captured by this `Fn` closure
16 | if foo.map_or(false, |f| f.foo()) {
| --- variable moved due to use in coroutine
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help: `Fn` and `FnMut` closures require captured values to be able to be consumed multiple times, but an `FnOnce` consume them only once
--> f111.rs:12:53
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12 | fn require_fn_trait<F: Future<Output = ()>>(_: impl Fn() -> F) {}
| ^^^^^^^^^
help: consider cloning the value if the performance cost is acceptable
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16 | if foo.clone().map_or(false, |f| f.foo()) {
| ++++++++
```
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Currently they are mostly named `cx`, which is a terrible name for a
type that impls `Printer`/`PrettyPrinter`, and is easy to confuse with
other types like `TyCtxt`. This commit changes them to `p`. A couple of
existing `p` variables had to be renamed to make way.
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Optimize region constraints
r? `@lcnr`
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This commit changes it to store a `Region` instead of a `RegionVid` for the `Var` cases:
- We avoid having to call `Region::new_var` to re-create `Region`s from
`RegionVid`s in a few places, avoiding the interning process, giving a
small perf win. (At the cost of the type allowing some invalid
combinations of values.)
- All the cases now store two `Region`s, so the commit also separates
the `ConstraintKind` (a new type) from the `sub` and `sup` arguments
in `Constraint`.
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The fields are public, so this doesn't need a method, normal
deconstruction and/or field access is good enough.
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Signed-off-by: xizheyin <xizheyin@smail.nju.edu.cn>
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Some `let chains` clean-up
Not sure if this kind of clean-up is welcoming because of size, but I decided to try out one
r? compiler
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When encountering a moved value of a type that isn't `Clone` because of unmet obligations, but where all the unmet predicates reference crate-local types, mention them and suggest cloning, as we do in other cases already:
```
error[E0507]: cannot move out of `foo`, a captured variable in an `Fn` closure
--> f111.rs:14:25
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13 | fn do_stuff(foo: Option<Foo>) {
| --- captured outer variable
14 | require_fn_trait(|| async {
| -- ^^^^^ `foo` is moved here
| |
| captured by this `Fn` closure
15 | if foo.map_or(false, |f| f.foo()) {
| ---
| |
| variable moved due to use in coroutine
| move occurs because `foo` has type `Option<Foo>`, which does not implement the `Copy` trait
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note: if `Foo` implemented `Clone`, you could clone the value
--> f111.rs:4:1
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4 | struct Foo;
| ^^^^^^^^^^ consider implementing `Clone` for this type
...
15 | if foo.map_or(false, |f| f.foo()) {
| --- you could clone this value
```
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Tweak output for non-`Clone` values moved into closures
When we encounter a non-`Clone` value being moved into a closure, try to find the corresponding type of the binding being moved, if it is a `let`-binding or a function parameter. If any of those cases, we point at them with the note explaining that the type is not `Copy`, instead of giving that label to the place where it is captured. When it is a `let`-binding with no explicit type, we point at the initializer (if it fits in a single line).
```
error[E0507]: cannot move out of `foo`, a captured variable in an `Fn` closure
--> f111.rs:14:25
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13 | fn do_stuff(foo: Option<Foo>) {
| --- ----------- move occurs because `foo` has type `Option<Foo>`, which does not implement the `Copy` trait
| |
| captured outer variable
14 | require_fn_trait(|| async {
| -- ^^^^^ `foo` is moved here
| |
| captured by this `Fn` closure
15 | if foo.map_or(false, |f| f.foo()) {
| --- variable moved due to use in coroutine
```
instead of
```
error[E0507]: cannot move out of `foo`, a captured variable in an `Fn` closure
--> f111.rs:14:25
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13 | fn do_stuff(foo: Option<Foo>) {
| --- captured outer variable
14 | require_fn_trait(|| async {
| -- ^^^^^ `foo` is moved here
| |
| captured by this `Fn` closure
15 | if foo.map_or(false, |f| f.foo()) {
| ---
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| variable moved due to use in coroutine
| move occurs because `foo` has type `Option<Foo>`, which does not implement the `Copy` trait
```
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```
error[E0507]: cannot move out of `f`, a captured variable in an `FnMut` closure
--> $DIR/borrowck-call-is-borrow-issue-12224.rs:57:13
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LL | let mut f = move |g: Box<dyn FnMut(isize)>, b: isize| {
| ----- captured outer variable
...
LL | f(Box::new(|a| {
| --- captured by this `FnMut` closure
LL |
LL | foo(f);
| ^ move occurs because `f` has type `{closure@$DIR/borrowck-call-is-borrow-issue-12224.rs:52:17: 52:58}`, which does not implement the `Copy` trait
```
instead of
```
error[E0507]: cannot move out of `f`, a captured variable in an `FnMut` closure
--> $DIR/borrowck-call-is-borrow-issue-12224.rs:57:13
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LL | let mut f = move |g: Box<dyn FnMut(isize)>, b: isize| {
| _________-----___-
| | |
| | captured outer variable
LL | | let _ = s.len();
LL | | };
| |_____- move occurs because `f` has type `{closure@$DIR/borrowck-call-is-borrow-issue-12224.rs:52:17: 52:58}`, which does not implement the `Copy` trait
LL | f(Box::new(|a| {
| --- captured by this `FnMut` closure
LL |
LL | foo(f);
| ^ `f` is moved here
```
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Account not only for `fn` parameters when moving non-`Copy` values into closure, but also for let bindings.
```
error[E0507]: cannot move out of `bar`, a captured variable in an `FnMut` closure
--> $DIR/borrowck-move-by-capture.rs:9:29
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LL | let bar: Box<_> = Box::new(3);
| --- ------ move occurs because `bar` has type `Box<isize>`, which does not implement the `Copy` trait
| |
| captured outer variable
LL | let _g = to_fn_mut(|| {
| -- captured by this `FnMut` closure
LL | let _h = to_fn_once(move || -> isize { *bar });
| ^^^^^^^^^^^^^^^^ ---- variable moved due to use in closure
| |
| `bar` is moved here
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help: consider cloning the value before moving it into the closure
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LL ~ let value = bar.clone();
LL ~ let _h = to_fn_once(move || -> isize { value });
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```
```
error[E0507]: cannot move out of `y`, a captured variable in an `Fn` closure
--> $DIR/unboxed-closures-move-upvar-from-non-once-ref-closure.rs:12:9
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LL | let y = vec![format!("World")];
| - ---------------------- move occurs because `y` has type `Vec<String>`, which does not implement the `Copy` trait
| |
| captured outer variable
LL | call(|| {
| -- captured by this `Fn` closure
LL | y.into_iter();
| ^ ----------- `y` moved due to this method call
| |
| `y` is moved here
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note: `into_iter` takes ownership of the receiver `self`, which moves `y`
--> $SRC_DIR/core/src/iter/traits/collect.rs:LL:COL
help: you can `clone` the value and consume it, but this might not be your desired behavior
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LL | <Vec<String> as Clone>::clone(&y).into_iter();
| +++++++++++++++++++++++++++++++ +
help: consider cloning the value if the performance cost is acceptable
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LL | y.clone().into_iter();
| ++++++++
```
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When encountering a non-`Copy` value that is moved into a closure which is coming directly from a fn parameter, point at the parameter's type when mentioning it is not `Copy`.
Before:
```
error[E0507]: cannot move out of `foo`, a captured variable in an `Fn` closure
--> f111.rs:14:25
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13 | fn do_stuff(foo: Option<Foo>) {
| --- captured outer variable
14 | require_fn_trait(|| async {
| -- ^^^^^ `foo` is moved here
| |
| captured by this `Fn` closure
15 | if foo.map_or(false, |f| f.foo()) {
| ---
| |
| variable moved due to use in coroutine
| move occurs because `foo` has type `Option<Foo>`, which does not implement the `Copy` trait
```
After:
```
error[E0507]: cannot move out of `foo`, a captured variable in an `Fn` closure
--> f111.rs:14:25
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13 | fn do_stuff(foo: Option<Foo>) {
| --- ----------- move occurs because `foo` has type `Option<Foo>`, which does not implement the `Copy` trait
| |
| captured outer variable
14 | require_fn_trait(|| async {
| -- ^^^^^ `foo` is moved here
| |
| captured by this `Fn` closure
15 | if foo.map_or(false, |f| f.foo()) {
| --- variable moved due to use in coroutine
```
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Ensure they are always created using constructors.
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Rollup of 18 pull requests
Successful merges:
- rust-lang/rust#137843 (make RefCell unstably const)
- rust-lang/rust#140942 (const-eval: allow constants to refer to mutable/external memory, but reject such constants as patterns)
- rust-lang/rust#142549 (small iter.intersperse.fold() optimization)
- rust-lang/rust#142637 (Remove some glob imports from the type system)
- rust-lang/rust#142647 ([perf] Compute hard errors without diagnostics in impl_intersection_has_impossible_obligation)
- rust-lang/rust#142700 (Remove incorrect comments in `Weak`)
- rust-lang/rust#142927 (Add note to `find_const_ty_from_env`)
- rust-lang/rust#142967 (Fix RwLock::try_write documentation for WouldBlock condition)
- rust-lang/rust#142986 (Port `#[export_name]` to the new attribute parsing infrastructure)
- rust-lang/rust#143001 (Rename run always )
- rust-lang/rust#143010 (Update `browser-ui-test` version to `0.20.7`)
- rust-lang/rust#143015 (Add `sym::macro_pin` diagnostic item for `core::pin::pin!()`)
- rust-lang/rust#143033 (Expand const-stabilized API links in relnotes)
- rust-lang/rust#143041 (Remove cache for citool)
- rust-lang/rust#143056 (Move an ACE test out of the GCI directory)
- rust-lang/rust#143059 (Fix 1.88 relnotes)
- rust-lang/rust#143067 (Tracking issue number for `iter_macro`)
- rust-lang/rust#143073 (Fix some fixmes that were waiting for let chains)
Failed merges:
- rust-lang/rust#143020 (codegen_fn_attrs: make comment more precise)
r? `@ghost`
`@rustbot` modify labels: rollup
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