Provide suggestions through `rustc_confusables` annotations
Help with common API confusion, like asking for `push` when the data structure really has `append`.
```
error[E0599]: no method named `size` found for struct `Vec<{integer}>` in the current scope
--> $DIR/rustc_confusables_std_cases.rs:17:7
|
LL | x.size();
| ^^^^
|
help: you might have meant to use `len`
|
LL | x.len();
| ~~~
help: there is a method with a similar name
|
LL | x.resize();
| ~~~~~~
```
Fix#59450 (we can open subsequent tickets for specific cases).
Fix#108437:
```
error[E0599]: `Option<{integer}>` is not an iterator
--> f101.rs:3:9
|
3 | opt.flat_map(|val| Some(val));
| ^^^^^^^^ `Option<{integer}>` is not an iterator
|
::: /home/gh-estebank/rust/library/core/src/option.rs:571:1
|
571 | pub enum Option<T> {
| ------------------ doesn't satisfy `Option<{integer}>: Iterator`
|
= note: the following trait bounds were not satisfied:
`Option<{integer}>: Iterator`
which is required by `&mut Option<{integer}>: Iterator`
help: you might have meant to use `and_then`
|
3 | opt.and_then(|val| Some(val));
| ~~~~~~~~
```
On type error of method call arguments, look at confusables for suggestion. Fix#87212:
```
error[E0308]: mismatched types
--> f101.rs:8:18
|
8 | stuff.append(Thing);
| ------ ^^^^^ expected `&mut Vec<Thing>`, found `Thing`
| |
| arguments to this method are incorrect
|
= note: expected mutable reference `&mut Vec<Thing>`
found struct `Thing`
note: method defined here
--> /home/gh-estebank/rust/library/alloc/src/vec/mod.rs:2025:12
|
2025 | pub fn append(&mut self, other: &mut Self) {
| ^^^^^^
help: you might have meant to use `push`
|
8 | stuff.push(Thing);
| ~~~~
```
remove `sub_relations` from the `InferCtxt`
While doing so, I tried to remove the `delay_span_bug` in `rematch_impl` again, which lead me to discover another `freshen` bug, fixing that one in the second commit. See commit descriptions for the reasoning behind each change.
r? `@compiler-errors`
Do not provide a structured suggestion when the arguments don't match.
```
error[E0599]: no method named `test_mut` found for struct `Vec<{integer}>` in the current scope
--> $DIR/auto-ref-slice-plus-ref.rs:7:7
|
LL | a.test_mut();
| ^^^^^^^^
|
= help: items from traits can only be used if the trait is implemented and in scope
note: `MyIter` defines an item `test_mut`, perhaps you need to implement it
--> $DIR/auto-ref-slice-plus-ref.rs:14:1
|
LL | trait MyIter {
| ^^^^^^^^^^^^
help: there is a method `get_mut` with a similar name, but with different arguments
--> $SRC_DIR/core/src/slice/mod.rs:LL:COL
```
Consider methods beyond inherent ones when suggesting typos.
```
error[E0599]: no method named `owned` found for reference `&dyn Foo` in the current scope
--> $DIR/object-pointer-types.rs:11:7
|
LL | fn owned(self: Box<Self>);
| --------- the method might not be found because of this arbitrary self type
...
LL | x.owned();
| ^^^^^ help: there is a method with a similar name: `to_owned`
```
Fix#101013.
No need to `validate_alias_bound_self_from_param_env` in `assemble_alias_bound_candidates`
We already fully normalize the self type before we reach `assemble_alias_bound_candidates`, so there's no reason to double check that a projection is truly rigid by checking param-env bounds.
I think this is also blocked on us making sure to always normalize opaques: #120549.
r? lcnr
Don't ICE when hitting overflow limit in fulfillment loop in next solver
As the title says, let's not ICE when hitting the overflow limit in fulfill. On the other hand, we don't want to treat these as true errors, since it means that whether something is considered a true error or an ambiguity is dependent on overflow handling in the solver, which seems not worth it.
Now that we use the presence of true errors in fulfillment for implicit negative coherence, we especially don't want to tie together coherence and overflow.
I guess I could also drain these errors out of fulfillment and put them into some `ambiguities` storage so we could return them in `select_all_or_error` without having to re-process them every time we call `select_where_possible`. Let me know if that's desired.
r? lcnr
deduplicate infer var instantiation
Having 3 separate implementations of one of the most subtle parts of our type system is not a good strategy if we want to maintain a sound type system ✨ while working on this I already found some subtle bugs in the existing code, so that's awesome 🎉 cc #121159
This was necessary as I am not confident in my nll changes in #119106, so I am first cleaning this up in a separate PR.
r? `@BoxyUwU`
Consider principal trait ref's auto-trait super-traits in dyn upcasting
Given traits like:
```rust
trait Subtrait: Supertrait + Send {}
trait Supertrait {}
```
We should be able to upcast `dyn Subtrait` to `dyn Supertrait + Send`. This is not currently possible, because when upcasting, we look at the list of auto traits in the object type (`dyn Subtrait`, which has no auto traits in its bounds) and compare them to the target's auto traits (`dyn Supertrait + Send`, which has `Send` in its bound).
Since the target has auto traits that are not present in the source, the upcasting fails. This is overly restrictive, since `dyn Subtrait` will always implement `Send` via its built-in object impl. I propose to loosen this restriction here.
r? types
---
### ~~Aside: Fix this in astconv instead?~~
### edit: This causes too many failures. See https://github.com/rust-lang/rust/pull/119825#issuecomment-1890847150
We may also fix this by by automatically elaborating all auto-trait supertraits during `AstConv::conv_object_ty_poly_trait_ref`. That is, we can make it so that `dyn Subtrait` is elaborated into the same type of `dyn Subtrait + Send`.
I'm open to considering this solution instead, but it would break coherence in the following example:
```rust
trait Foo: Send {}
trait Bar {}
impl Bar for dyn Foo {}
impl Bar for dyn Foo + Send {}
//~^ This would begin to be an overlapping impl.
```
Continue compilation after check_mod_type_wf errors
The ICEs fixed here were probably reachable through const eval gymnastics before, but now they are easily reachable without that, too.
The new errors are often bugfixes, where useful errors were missing, because they were reported after the early abort. In other cases sometimes they are just duplication of already emitted errors, which won't be user-visible due to deduplication.
fixes https://github.com/rust-lang/rust/issues/120860
Fix suggestion span for `?Sized` when param type has default
Fixes#120878
Diagnostic suggests adding `: ?Sized` in an incorrect place if a type parameter default is present
r? `@fmease`
Be less confident when `dyn` suggestion is not checked for object safety
#120275 no longer checks bare traits for object safety when making a `dyn` suggestion on Rust < 2021. In this case, qualify the suggestion with a note that the trait must be object safe, to prevent user confusion as seen in #116434
r? ```@fmease```
improve normalization of `Pointee::Metadata`
This PR makes it so that `<Wrapper<Tail> as Pointee>::Metadata` is normalized to `<Tail as Pointee>::Metadata` if we don't know `Wrapper<Tail>: Sized`. With that, the trait solver can prove projection predicates like `<Wrapper<Tail> as Pointee>::Metadata == <Tail as Pointee>::Metadata`, which makes it possible to use the metadata APIs to cast between the tail and the wrapper:
```rust
#![feature(ptr_metadata)]
use std::ptr::{self, Pointee};
fn cast_same_meta<T: ?Sized, U: ?Sized>(ptr: *const T) -> *const U
where
T: Pointee<Metadata = <U as Pointee>::Metadata>,
{
let (thin, meta) = ptr.to_raw_parts();
ptr::from_raw_parts(thin, meta)
}
struct Wrapper<T: ?Sized>(T);
fn cast_to_wrapper<T: ?Sized>(ptr: *const T) -> *const Wrapper<T> {
cast_same_meta(ptr)
}
```
Previously, this failed to compile:
```
error[E0271]: type mismatch resolving `<Wrapper<T> as Pointee>::Metadata == <T as Pointee>::Metadata`
--> src/lib.rs:16:5
|
15 | fn cast_to_wrapper<T: ?Sized>(ptr: *const T) -> *const Wrapper<T> {
| - found this type parameter
16 | cast_same_meta(ptr)
| ^^^^^^^^^^^^^^ expected `Wrapper<T>`, found type parameter `T`
|
= note: expected associated type `<Wrapper<T> as Pointee>::Metadata`
found associated type `<T as Pointee>::Metadata`
= note: an associated type was expected, but a different one was found
```
(Yes, you can already do this with `as` casts. But using functions is so much ✨ *safer* ✨, because you can't change the metadata on accident.)
---
This PR essentially changes the built-in impls of `Pointee` from this:
```rust
// before
impl Pointee for u8 {
type Metadata = ();
}
impl Pointee for [u8] {
type Metadata = usize;
}
// ...
impl Pointee for Wrapper<u8> {
type Metadata = ();
}
impl Pointee for Wrapper<[u8]> {
type Metadata = usize;
}
// ...
// This impl is only selected if `T` is a type parameter or unnormalizable projection or opaque type.
fallback impl<T: ?Sized> Pointee for Wrapper<T>
where
Wrapper<T>: Sized
{
type Metadata = ();
}
// This impl is only selected if `T` is a type parameter or unnormalizable projection or opaque type.
fallback impl<T /*: Sized */> Pointee for T {
type Metadata = ();
}
```
to this:
```rust
// after
impl Pointee for u8 {
type Metadata = ();
}
impl Pointee for [u8] {
type Metadata = usize;
}
// ...
impl<T: ?Sized> Pointee for Wrapper<T> {
// in the old solver this will instead project to the "deep" tail directly,
// e.g. `Wrapper<Wrapper<T>>::Metadata = T::Metadata`
type Metadata = <T as Pointee>::Metadata;
}
// ...
// This impl is only selected if `T` is a type parameter or unnormalizable projection or opaque type.
fallback impl<T /*: Sized */> Pointee for T {
type Metadata = ();
}
```
Rollup of 9 pull requests
Successful merges:
- #119592 (resolve: Unload speculatively resolved crates before freezing cstore)
- #120103 (Make it so that async-fn-in-trait is compatible with a concrete future in implementation)
- #120206 (hir: Make sure all `HirId`s have corresponding HIR `Node`s)
- #120214 (match lowering: consistently lower bindings deepest-first)
- #120688 (GVN: also turn moves into copies with projections)
- #120702 (docs: also check the inline stmt during redundant link check)
- #120727 (exhaustiveness: Prefer "`0..MAX` not covered" to "`_` not covered")
- #120734 (Add `SubdiagnosticMessageOp` as a trait alias.)
- #120739 (improve pretty printing for associated items in trait objects)
r? `@ghost`
`@rustbot` modify labels: rollup
improve pretty printing for associated items in trait objects
* Don't print a binder in front of associated items, because it's not valid syntax.
* e.g. print `dyn for<'a> Trait<'a, Assoc = &'a u8>` instead of `dyn for<'a> Trait<'a, for<'a> Assoc = &'a u8>`.
* Don't print associated items that are implied by a supertrait bound.
* e.g. if we have `trait Sub: Super<Assoc = u8> {}`, then just print `dyn Sub` instead of `dyn Sub<Assoc = u8>`.
I've added the test in the first commit, so you can see the diff of the compiler output in the second commit.
