Sometimes move errors are because of a misplaced `continue`, but we didn't
surface that anywhere. Now when there are more than one set of nested loops
we show them out and point at the `continue` and `break` expressions within
that might need to go elsewhere.
```
error[E0382]: use of moved value: `foo`
--> $DIR/nested-loop-moved-value-wrong-continue.rs:46:18
|
LL | for foo in foos {
| ---
| |
| this reinitialization might get skipped
| move occurs because `foo` has type `String`, which does not implement the `Copy` trait
...
LL | for bar in &bars {
| ---------------- inside of this loop
...
LL | baz.push(foo);
| --- value moved here, in previous iteration of loop
...
LL | qux.push(foo);
| ^^^ value used here after move
|
note: verify that your loop breaking logic is correct
--> $DIR/nested-loop-moved-value-wrong-continue.rs:41:17
|
LL | for foo in foos {
| ---------------
...
LL | for bar in &bars {
| ----------------
...
LL | continue;
| ^^^^^^^^ this `continue` advances the loop at line 33
help: consider moving the expression out of the loop so it is only moved once
|
LL ~ let mut value = baz.push(foo);
LL ~ for bar in &bars {
LL |
...
LL | if foo == *bar {
LL ~ value;
|
help: consider cloning the value if the performance cost is acceptable
|
LL | baz.push(foo.clone());
| ++++++++
```
Fix#92531.
When encountering a move error on a value within a loop of any kind,
identify if the moved value belongs to a call expression that should not
be cloned and avoid the semantically incorrect suggestion. Also try to
suggest moving the call expression outside of the loop instead.
```
error[E0382]: use of moved value: `vec`
--> $DIR/recreating-value-in-loop-condition.rs:6:33
|
LL | let vec = vec!["one", "two", "three"];
| --- move occurs because `vec` has type `Vec<&str>`, which does not implement the `Copy` trait
LL | while let Some(item) = iter(vec).next() {
| ----------------------------^^^--------
| | |
| | value moved here, in previous iteration of loop
| inside of this loop
|
note: consider changing this parameter type in function `iter` to borrow instead if owning the value isn't necessary
--> $DIR/recreating-value-in-loop-condition.rs:1:17
|
LL | fn iter<T>(vec: Vec<T>) -> impl Iterator<Item = T> {
| ---- ^^^^^^ this parameter takes ownership of the value
| |
| in this function
help: consider moving the expression out of the loop so it is only moved once
|
LL ~ let mut value = iter(vec);
LL ~ while let Some(item) = value.next() {
|
```
We use the presence of a `break` in the loop that would be affected by
the moved value as a heuristic for "shouldn't be cloned".
Fix#121466.
Detect calls to .clone() on T: !Clone types on borrowck errors
When encountering a lifetime error on a type that *holds* a type that doesn't implement `Clone`, explore the item's body for potential calls to `.clone()` that are only cloning the reference `&T` instead of `T` because `T: !Clone`. If we find this, suggest `T: Clone`.
```
error[E0502]: cannot borrow `*list` as mutable because it is also borrowed as immutable
--> $DIR/clone-on-ref.rs:7:5
|
LL | for v in list.iter() {
| ---- immutable borrow occurs here
LL | cloned_items.push(v.clone())
| ------- this call doesn't do anything, the result is still `&T` because `T` doesn't implement `Clone`
LL | }
LL | list.push(T::default());
| ^^^^^^^^^^^^^^^^^^^^^^^ mutable borrow occurs here
LL |
LL | drop(cloned_items);
| ------------ immutable borrow later used here
|
help: consider further restricting this bound
|
LL | fn foo<T: Default + Clone>(list: &mut Vec<T>) {
| +++++++
```
```
error[E0505]: cannot move out of `x` because it is borrowed
--> $DIR/clone-on-ref.rs:23:10
|
LL | fn qux(x: A) {
| - binding `x` declared here
LL | let a = &x;
| -- borrow of `x` occurs here
LL | let b = a.clone();
| ------- this call doesn't do anything, the result is still `&A` because `A` doesn't implement `Clone`
LL | drop(x);
| ^ move out of `x` occurs here
LL |
LL | println!("{b:?}");
| ----- borrow later used here
|
help: consider annotating `A` with `#[derive(Clone)]`
|
LL + #[derive(Clone)]
LL | struct A;
|
```
Fix#48677.
hir: Remove `opt_local_def_id_to_hir_id` and `opt_hir_node_by_def_id`
Also replace a few `hir_node()` calls with `hir_node_by_def_id()`.
Follow up to https://github.com/rust-lang/rust/pull/120943.
Cleanup `MirBorrowckCtxt::prefixes`
Some of the uses of this method aren't necessary anymore and `PrefixSet::Supporting` is not used anywhere.
With `PrefixSet::Supporting` removed, this could technically be moved to an extension trait on `PlaceRef`. However, it would have to be moved back to `MirBorrowckCtxt` when the `Derefer` MIR pass is moved before borrowck so I didn't.
When encountering a lifetime error on a type that *holds* a type that
doesn't implement `Clone`, explore the item's body for potential calls
to `.clone()` that are only cloning the reference `&T` instead of `T`
because `T: !Clone`. If we find this, suggest `T: Clone`.
```
error[E0502]: cannot borrow `*list` as mutable because it is also borrowed as immutable
--> $DIR/clone-on-ref.rs:7:5
|
LL | for v in list.iter() {
| ---- immutable borrow occurs here
LL | cloned_items.push(v.clone())
| ------- this call doesn't do anything, the result is still `&T` because `T` doesn't implement `Clone`
LL | }
LL | list.push(T::default());
| ^^^^^^^^^^^^^^^^^^^^^^^ mutable borrow occurs here
LL |
LL | drop(cloned_items);
| ------------ immutable borrow later used here
|
help: consider further restricting this bound
|
LL | fn foo<T: Default + Clone>(list: &mut Vec<T>) {
| +++++++
```
```
error[E0505]: cannot move out of `x` because it is borrowed
--> $DIR/clone-on-ref.rs:23:10
|
LL | fn qux(x: A) {
| - binding `x` declared here
LL | let a = &x;
| -- borrow of `x` occurs here
LL | let b = a.clone();
| ------- this call doesn't do anything, the result is still `&A` because `A` doesn't implement `Clone`
LL | drop(x);
| ^ move out of `x` occurs here
LL |
LL | println!("{b:?}");
| ----- borrow later used here
|
help: consider annotating `A` with `#[derive(Clone)]`
|
LL + #[derive(Clone)]
LL | struct A;
|
```
Distinguish between library and lang UB in assert_unsafe_precondition
As described in https://github.com/rust-lang/rust/pull/121583#issuecomment-1963168186, `assert_unsafe_precondition` now explicitly distinguishes between language UB (conditions we explicitly optimize on) and library UB (things we document you shouldn't do, and maybe some library internals assume you don't do).
`debug_assert_nounwind` was originally added to avoid the "only at runtime" aspect of `assert_unsafe_precondition`. Since then the difference between the macros has gotten muddied. This totally revamps the situation.
Now _all_ preconditions shall be checked with `assert_unsafe_precondition`. If you have a precondition that's only checkable at runtime, do a `const_eval_select` hack, as done in this PR.
r? RalfJung
Use `ControlFlow` in visitors.
Follow up to #121256
This does have a few small behaviour changes in some diagnostic output where the visitor will now find the first match rather than the last match. The change in `find_anon_types.rs` has the only affected test. I don't see this being an issue as the last occurrence isn't any better of a choice than the first.
Make TAITs and ATPITs capture late-bound lifetimes in scope
This generalizes the behavior that RPITs have, where they duplicate their in-scope lifetimes so that they will always *reify* late-bound lifetimes that they capture. This allows TAITs and ATPITs to properly error when they capture in-scope late-bound lifetimes.
r? `@oli-obk` cc `@aliemjay`
Fixes#122093 and therefore https://github.com/rust-lang/rust/pull/120700#issuecomment-1981213868
Add asm goto support to `asm!`
Tracking issue: #119364
This PR implements asm-goto support, using the syntax described in "future possibilities" section of [RFC2873](https://rust-lang.github.io/rfcs/2873-inline-asm.html#asm-goto).
Currently I have only implemented the `label` part, not the `fallthrough` part (i.e. fallthrough is implicit). This doesn't reduce the expressive though, since you can use label-break to get arbitrary control flow or simply set a value and rely on jump threading optimisation to get the desired control flow. I can add that later if deemed necessary.
r? ``@Amanieu``
cc ``@ojeda``
Prior to the previous commit, `#[rust_lint_diagnostics]` attributes
could only be used on methods with an `impl Into<{D,Subd}iagMessage>`
parameter. But there are many other nearby diagnostic methods (e.g.
`Diag::span`) that don't take such a parameter and should have the
attribute.
This commit adds the missing attribute to these `Diag` methods. This
requires adding some missing
`#[allow(rustc::diagnostic_outside_of_impl)]` markers at call sites to
these methods.
Currently it only checks calls to functions marked with
`#[rustc_lint_diagnostics]`. This commit changes it to check calls to
any function with an `impl Into<{D,Subd}iagMessage>` parameter. This
greatly improves its coverage and doesn't rely on people remembering to
add `#[rustc_lint_diagnostics]`.
The commit also adds `#[allow(rustc::untranslatable_diagnostic)`]
attributes to places that need it that are caught by the improved lint.
These places that might be easy to convert to translatable diagnostics.
Finally, it also:
- Expands and corrects some comments.
- Does some minor formatting improvements.
- Adds missing `DecorateLint` cases to
`tests/ui-fulldeps/internal-lints/diagnostics.rs`.
Add `StructurallyRelateAliases` to allow instantiating infer vars with rigid aliases.
Change `instantiate_query_response` to be infallible in the new solver. This requires canonicalization to not hide any information used by the query, so weaken
universe compression. It also modifies `term_is_fully_unconstrained` to allow
region inference variables in a higher universe.
fix generalizer unsoundness
I ended up getting confused while trying to flip the variances when flipping the order. Should be all right now.
This is only exploitable when generalizing if the `ambient_variance` of the relation is `Contravariant`. This can currently only be the case in the NLL generalizer which only rarely generalizes, causing us to miss this regression. Very much an issue with #121462 however.
