Account for sealed traits in privacy and trait bound errors
On trait bound errors caused by super-traits, identify if the super-trait is publicly accessibly and if not, explain "sealed traits".
```
error[E0277]: the trait bound `S: Hidden` is not satisfied
--> $DIR/sealed-trait-local.rs:17:20
|
LL | impl a::Sealed for S {}
| ^ the trait `Hidden` is not implemented for `S`
|
note: required by a bound in `Sealed`
--> $DIR/sealed-trait-local.rs:3:23
|
LL | pub trait Sealed: self:🅱️:Hidden {
| ^^^^^^^^^^^^^^^ required by this bound in `Sealed`
= note: `Sealed` is a "sealed trait", because to implement it you also need to implelement `a:🅱️:Hidden`, which is not accessible; this is usually done to force you to use one of the provided types that already implement it
```
Deduplicate privacy errors that point to the same path segment even if their deduplication span are different.
When encountering a path that is not reachable due to privacy constraints path segments other than the last, keep metadata for the last path segment's `Res` in order to look for alternative import paths for that item to suggest. If there are none, be explicit that the item is not accessible.
```
error[E0603]: module `b` is private
--> $DIR/re-exported-trait.rs:11:9
|
LL | impl a:🅱️:Trait for S {}
| ^ private module
|
note: the module `b` is defined here
--> $DIR/re-exported-trait.rs:5:5
|
LL | mod b {
| ^^^^^
help: consider importing this trait through its public re-export instead
|
LL | impl a::Trait for S {}
| ~~~~~~~~
```
```
error[E0603]: module `b` is private
--> $DIR/private-trait.rs:8:9
|
LL | impl a:🅱️:Hidden for S {}
| ^ ------ trait `b` is not publicly reachable
| |
| private module
|
note: the module `b` is defined here
--> $DIR/private-trait.rs:2:5
|
LL | mod b {
| ^^^^^
```
Suggest publicly accessible paths for items in private mod:
When encountering a path in non-import situations that are not reachable
due to privacy constraints, search for any public re-exports that the
user could use instead.
Track whether an import suggestion is offering a re-export.
When encountering a path with private segments, mention if the item at
the final path segment is not publicly accessible at all.
Add item visibility metadata to privacy errors from imports:
On unreachable imports, record the item that was being imported in order
to suggest publicly available re-exports or to be explicit that the item
is not available publicly from any path.
In order to allow this, we add a mode to `resolve_path` that will not
add new privacy errors, nor return early if it encounters one. This way
we can get the `Res` corresponding to the final item in the import,
which is used in the privacy error machinery.
When implementing a public trait with a private super-trait, we now emit
a note that the missing bound is not going to be able to be satisfied,
and we explain the concept of a sealed trait.
Print def_id on EarlyBoundRegion debug
It's not the first time that I can't make sense out of the default debug print on `EarlyBoundRegion`. As I was working on #112682 I needed this.
I was doing some git archeology and found that we used to print everything dfbc9608ce/src/librustc/util/ppaux.rs (L425-L430) but we lost the ability in some refactor midway.
Don't substitute a GAT that has mismatched generics in `OpaqueTypeCollector`
Fixes#111828
I didn't put up minimized UI tests for #112510 or #112873 because they'd minimize to literally the same code, but with different substs on the trait/impl. I don't think that warrants duplicate tests given the nature of the fix.
r? `@oli-obk`
----
Side-note: I checked, and this isn't fixed by #112652 -- I think we discussed whether or not that PR fixed it either intentionally or by accident. The code here isn't really touched by that PR either as far as I can tell?
Also, sorry, did some other drive-bys. Hope it doesn't make rebasing #112652 too difficult 😅
Fix union fields display
So two bugs in this screenshot: no whitespace between field name and type name, both fields are on the same line. Both problems come from issues in the templates because all whitespace are removed if a askama "command" follows.
r? `@notriddle`
Warn on unused `offset_of!()` result
The usage of `core::hint::must_use()` means that we don't get a specialized message. I figured out that since there are plenty of other methods that just have `#[must_use]` with no message it'll be fine, but it is a bit unfortunate that the error mentions `must_use` and not `offset_of!`.
Fixes#111669.
Add `lazy_type_alias` feature gate
Add the `type_alias_type` to be able to have the weak alias used without restrictions.
Part of #112792.
cc `@compiler-errors`
r? `@oli-obk`
[rustdoc] partially fix invalid files creation
Part of #111249. It only removes generation for modules which shouldn't exist. For files, we need the compiler to keep re-export information alive for external items so we can actually have the right path to their location as it's currently not generating them correctly.
In case the item is inlined, it shouldn't (and neither should its children) get a file generated.
r? ```@notriddle```
Syntactically accept `become` expressions (explicit tail calls experiment)
This adds `ast::ExprKind::Become`, implements parsing and properly gates the feature.
cc `@scottmcm`
There's no need to store it in `Queries`. We can just use a local
variable, because it's always used shortly after it's produced.
The commit also removes the `tcx.analysis()` call in `ongoing_codegen`,
because it's easy to ensure that's done beforehand.
All this makes the dataflow within `run_compiler` easier to follow, at
the cost of making one test slightly more verbose, which I think is a
good tradeoff.
Revert #112758 and add test case
Fixes#112831.
Cannot unwrap `update_resolution` for `resolution.single_imports.remove(&Interned::new_unchecked(import));` because there is a relationship between the `Import` and `&NameBinding` in `NameResolution`. This issue caused by my unfamiliarity with the data structure and I apologize for it.
This PR had been reverted, and test case have been added.
r? `@Nilstrieb`
cc `@petrochenkov`
Sort the errors from arguments checking so that suggestions are handled properly
Fixes#112507
The algorithm of `find_issue` does not make sure the index comes out in order, which will make suggesting `remove` or `add` arguments broken in some cases.
Modifying the algorithm to obey order involves much more trivial change, so it's better to order the `errors` after iterations.
Rustdoc: search: color item type and reduce size to avoid clashing
- rustdoc: search: color item type same as item
- rustdoc: search: reduce item type size to 0.875rem to avoid clashing with path and item
Add `implement_via_object` to `rustc_deny_explicit_impl` to control object candidate assembly
Some built-in traits are special, since they are used to prove facts about the program that are important for later phases of compilation such as codegen and CTFE. For example, the `Unsize` trait is used to assert to the compiler that we are able to unsize a type into another type. It doesn't have any methods because it doesn't actually *instruct* the compiler how to do this unsizing, but this is later used (alongside an exhaustive match of combinations of unsizeable types) during codegen to generate unsize coercion code.
Due to this, these built-in traits are incompatible with the type erasure provided by object types. For example, the existence of `dyn Unsize<T>` does not mean that the compiler is able to unsize `Box<dyn Unsize<T>>` into `Box<T>`, since `Unsize` is a *witness* to the fact that a type can be unsized, and it doesn't actually encode that unsizing operation in its vtable as mentioned above.
The old trait solver gets around this fact by having complex control flow that never considers object bounds for certain built-in traits:
2f896da247/compiler/rustc_trait_selection/src/traits/select/candidate_assembly.rs (L61-L132)
However, candidate assembly in the new solver is much more lovely, and I'd hate to add this list of opt-out cases into the new solver. Instead of maintaining this complex and hard-coded control flow, instead we can make this a property of the trait via a built-in attribute. We already have such a build attribute that's applied to every single trait that we care about: `rustc_deny_explicit_impl`. This PR adds `implement_via_object` as a meta-item to that attribute that allows us to opt a trait out of object-bound candidate assembly as well.
r? `@lcnr`
Don't consider TAIT normalizable to hidden ty if it would result in impossible item bounds
See test for example where we shouldn't consider it possible to alias-relate a TAIT and hidden type.
r? `@lcnr`
Don't ICE on bound var in `reject_fn_ptr_impls`
We may try to use an impl like `impl<T: FnPtr> PartialEq {}` to satisfy a predicate like `for<T> T: PartialEq` -- don't ICE in that case.
Fixes#112735
Treat TAIT equation as always ambiguous in coherence
Not sure why we weren't treating all TAIT equality as ambiguous -- this behavior combined with `DefineOpaqueTypes::No` leads to coherence overlap failures, since we incorrectly consider impls as not overlapping because the obligation `T: From<Foo>` doesn't hold.
Fixes#112765
Continue folding in query normalizer on weak aliases
Fixes#112752Fixes#112731 (same root cause, so didn't make a test for it)
fixes#112776
r? ```@oli-obk```
