Lower them into a single item with multiple resolutions instead.
This also allows to remove additional `NodId`s and `DefId`s related to those additional items.
Optimizations removed in the previous commit required this function to behave incorrectly, but now those optimizations are gone so we can fix the bug.
Fixes https://github.com/rust-lang/rust/issues/104249
First, they require eagerly calculating private visibility (current normal module), which is somewhat expensive.
Private visibilities are also lost once calculated, instead of being cached in the table.
Second, I cannot prove that the optimizations are correct.
Maybe they can be partially reinstated in the future in cases when it's cheap and provably correct to do them.
They will also probably be merged into `fn update` in that case.
Partially fixes https://github.com/rust-lang/rust/issues/104249
Fixes https://github.com/rust-lang/rust/issues/104539
resolve: Set effective visibilities for imports more precisely
Instead of setting them for all primary and additional IDs of the import, only set them for the binding's true ID.
Relax priv-in-pub lint on generic bounds and where clauses of trait impls.
The priv-in-pub lint is a legacy mechanism of the compiler, supplanted by a reachability-based [type privacy](https://github.com/rust-lang/rfcs/blob/master/text/2145-type-privacy.md) analysis. This PR does **not** relax type privacy; it only relaxes the lint (as proposed by the type privacy RFC) in the case of trait impls.
## Current Behavior
On public trait impls, it's currently an **error** to have a `where` bound constraining a private type with a trait:
```rust
pub trait Trait {}
pub struct Type {}
struct Priv {}
impl Trait for Priv {}
impl Trait for Type
where
Priv: Trait // ERROR
{}
```
...and it's a **warning** to have have a public type constrained by a private trait:
```rust
pub trait Trait {}
pub struct Type {}
pub struct Pub {}
trait Priv {}
impl Priv for Pub {}
impl Trait for Type
where
Pub: Priv // WARNING
{}
```
This lint applies to `where` clauses in other contexts, too; e.g. on free functions:
```rust
struct Priv<T>(T);
pub trait Pub {}
impl<T: Pub> Pub for Priv<T> {}
pub fn function<T>()
where
Priv<T>: Pub // WARNING
{}
```
**These constraints could be relaxed without issue.**
## New Behavior
This lint is relaxed for `where` clauses on trait impls, such that it's okay to have a `where` bound constraining a private type with a trait:
```rust
pub trait Trait {}
pub struct Type {}
struct Priv {}
impl Trait for Priv {}
impl Trait for Type
where
Priv: Trait // OK
{}
```
...and it's okay to have a public type constrained by a private trait:
```rust
pub trait Trait {}
pub struct Type {}
pub struct Pub {}
trait Priv {}
impl Priv for Pub {}
impl Trait for Type
where
Pub: Priv // OK
{}
```
## Rationale
While the priv-in-pub lint is not essential for soundness, it *can* help programmers avoid pitfalls that would make their libraries difficult to use by others. For instance, such a lint *is* useful for free functions; e.g. if a downstream crate tries to call the `function` in the previous snippet in a generic context:
```rust
fn callsite<T>()
where
Priv<T>: Pub // ERROR: omitting this bound is a compile error, but including it is too
{
function::<T>()
}
```
...it cannot do so without repeating `function`'s `where` bound, which we cannot do because `Priv` is out-of-scope. A lint for this case is arguably helpful.
However, this same reasoning **doesn't** hold for trait impls. To call an unconstrained method on a public trait impl with private bounds, you don't need to forward those private bounds, you can forward the public trait:
```rust
mod upstream {
pub trait Trait {
fn method(&self) {}
}
pub struct Type<T>(T);
pub struct Pub<T>(T);
trait Priv {}
impl<T: Priv> Priv for Pub<T> {}
impl<T> Trait for Type<T>
where
Pub<T>: Priv // WARNING
{}
}
mod downstream {
use super::upstream::*;
fn function<T>(value: Type<T>)
where
Type<T>: Trait // <- no private deets!
{
value.method();
}
}
```
**This PR only eliminates the lint on trait impls.** It leaves it intact for all other contexts, including trait definitions, inherent impls, and function definitions. It doesn't need to exist in those cases either, but I figured I'd first target a case where it's mostly pointless.
## Other Notes
- See discussion [on zulip](https://rust-lang.zulipchat.com/#narrow/stream/213817-t-lang/topic/relax.20priv-in-pub.20lint.20for.20trait.20impl.20.60where.60.20bounds/near/222458397).
- This PR effectively reverts #79291.
Clarify error messages caused by re-exporting `pub(crate)` visibility to outside
This PR clarifies error messages and suggestions caused by re-exporting pub(crate) visibility outside the crate.
Here is a small example ([Rust Playground](https://play.rust-lang.org/?version=nightly&mode=debug&edition=2018&gist=e2cd0bd4422d4f20e6522dcbad167d3b)):
```rust
mod m {
pub(crate) enum E {}
}
pub use m::E;
fn main() {}
```
This code is compiled to:
```
error[E0365]: `E` is private, and cannot be re-exported
--> prog.rs:4:9
|
4 | pub use m::E;
| ^^^^ re-export of private `E`
|
= note: consider declaring type or module `E` with `pub`
error: aborting due to previous error
For more information about this error, try `rustc --explain E0365`.
```
However, enum `E` is actually public to the crate, not private totally—nevertheless, rustc treats `pub(crate)` and private visibility as the same on the error messages. They are not clear and should be segmented distinctly.
By applying changes in this PR, the error message below will be the following message that would be clearer:
```
error[E0365]: `E` is only public to inside of the crate, and cannot be re-exported outside
--> prog.rs:4:9
|
4 | pub use m::E;
| ^^^^ re-export of crate public `E`
|
= note: consider declaring type or module `E` with `pub`
error: aborting due to previous error
For more information about this error, try `rustc --explain E0365`.
```
Index and hash HIR as part of lowering
Part of https://github.com/rust-lang/rust/pull/88186
~Based on https://github.com/rust-lang/rust/pull/88880 (see merge commit).~
Once HIR is lowered, it is later indexed by the `index_hir` query and hashed for `crate_hash`. This PR moves those post-processing steps to lowering itself. As a side objective, the HIR crate data structure is refactored as an `IndexVec<LocalDefId, Option<OwnerInfo<'hir>>>` where `OwnerInfo` stores all the relevant information for an HIR owner.
r? `@michaelwoerister`
cc `@petrochenkov`
