Add `never_patterns` feature gate
This PR adds the feature gate and most basic parsing for the experimental `never_patterns` feature. See the tracking issue (https://github.com/rust-lang/rust/issues/118155) for details on the experiment.
`@scottmcm` has agreed to be my lang-team liaison for this experiment.
Currently we always do this:
```
use rustc_fluent_macro::fluent_messages;
...
fluent_messages! { "./example.ftl" }
```
But there is no need, we can just do this everywhere:
```
rustc_fluent_macro::fluent_messages! { "./example.ftl" }
```
which is shorter.
The `fluent_messages!` macro produces uses of
`crate::{D,Subd}iagnosticMessage`, which means that every crate using
the macro must have this import:
```
use rustc_errors::{DiagnosticMessage, SubdiagnosticMessage};
```
This commit changes the macro to instead use
`rustc_errors::{D,Subd}iagnosticMessage`, which avoids the need for the
imports.
By default, `newtype_index!` types get a default `Encodable`/`Decodable`
impl. You can opt out of this with `custom_encodable`. Opting out is the
opposite to how Rust normally works with autogenerated (derived) impls.
This commit inverts the behaviour, replacing `custom_encodable` with
`encodable` which opts into the default `Encodable`/`Decodable` impl.
Only 23 of the 59 `newtype_index!` occurrences need `encodable`.
Even better, there were eight crates with a dependency on
`rustc_serialize` just from unused default `Encodable`/`Decodable`
impls. This commit removes that dependency from those eight crates.
They've been deprecated for four years.
This commit includes the following changes.
- It eliminates the `rustc_plugin_impl` crate.
- It changes the language used for lints in
`compiler/rustc_driver_impl/src/lib.rs` and
`compiler/rustc_lint/src/context.rs`. External lints are now called
"loaded" lints, rather than "plugins" to avoid confusion with the old
plugins. This only has a tiny effect on the output of `-W help`.
- E0457 and E0498 are no longer used.
- E0463 is narrowed, now only relating to unfound crates, not plugins.
- The `plugin` feature was moved from "active" to "removed".
- It removes the entire plugins chapter from the unstable book.
- It removes quite a few tests, mostly all of those in
`tests/ui-fulldeps/plugin/`.
Closes#29597.
Store #[deprecated] attribute's `since` value in parsed form
This PR implements the first followup bullet listed in https://github.com/rust-lang/rust/pull/117148#issue-1960240108.
We centralize error handling to the attribute parsing code in `compiler/rustc_attr/src/builtin.rs`, and thereby remove some awkward error codepaths from later phases of compilation that had to make sense of these #\[deprecated\] attributes, namely `compiler/rustc_passes/src/stability.rs` and `compiler/rustc_middle/src/middle/stability.rs`.
- Sort dependencies and features sections.
- Add `tidy` markers to the sorted sections so they stay sorted.
- Remove empty `[lib`] sections.
- Remove "See more keys..." comments.
Excluded files:
- rustc_codegen_{cranelift,gcc}, because they're external.
- rustc_lexer, because it has external use.
- stable_mir, because it has external use.
Implement `gen` blocks in the 2024 edition
Coroutines tracking issue https://github.com/rust-lang/rust/issues/43122
`gen` block tracking issue https://github.com/rust-lang/rust/issues/117078
This PR implements `gen` blocks that implement `Iterator`. Most of the logic with `async` blocks is shared, and thus I renamed various types that were referring to `async` specifically.
An example usage of `gen` blocks is
```rust
fn foo() -> impl Iterator<Item = i32> {
gen {
yield 42;
for i in 5..18 {
if i.is_even() { continue }
yield i * 2;
}
}
}
```
The limitations (to be resolved) of the implementation are listed in the tracking issue
It's a better name, and lets "active features" refer to the features
that are active in a particular program, due to being declared or
enabled by the edition.
The commit also renames `Features::enabled` as `Features::active` to
match this; I changed my mind and have decided that "active" is a little
better thatn "enabled" for this, particularly because a number of
pre-existing comments use "active" in this way.
Finally, the commit renames `Status::Stable` as `Status::Accepted`, to
match `ACCEPTED_FEATURES`.
rustdoc: show crate name beside smaller logo
*Blocked on https://github.com/rust-lang/cargo/pull/12800*
## Summary
In this PR, the crate name and version are always shown in the sidebar, even in subpages, and the lateral navigation is always shown in the sidebar, even in modules.
Clicking the crate name does the same thing clicking the logo always did: take you to the crate root (the crate's home page, at least within Rustdoc).
The Rust logo is also no longer shown by default for non-Rust docs.
### Screenshots
<details><summary>Before</summary>
| | Macro | Module |
|--|-------|--------|
| In crate |  |
| In module[^1] |  | 
[^1]: This PR also includes a bug fix for derive macros not showing up in the lateral navigation part of the sidebar
</details>
#### Whole sidebar screenshots
| | Macro | Module |
|--|-------|--------|
| In crate |  | 
| In module |  | 
#### Different logo configurations
| | Short crate name | Long crate name |
|---------|------------------|-----------------|
| Root | ![short-root] | ![long-root]
| Subpage | ![short-subpage] | ![long-subpage]
[short-root]: 9e2b4fa8-f581-4106-b562-1e0372c13f79
[short-subpage]: 8331cdb8-fa13-4671-a1e2-dcc1cdca7451
[long-root]: 7d377fec-0f1d-4343-9f82-0e35a8f58056
[long-subpage]: 3b3094a4-63c9-477c-8c15-b6075837df30
##### Without a logo
### Preview pages
https://notriddle.com/rustdoc-html-demo-5/sidebar-layout-rocket/rocket/index.htmlhttps://notriddle.com/rustdoc-html-demo-5/sidebar-layout-rocket/rocket_sync_db_pools/index.htmlhttps://notriddle.com/rustdoc-html-demo-5/sidebar-layout-rust-compiler/index.htmlhttps://notriddle.com/rustdoc-html-demo-5/sidebar-layout-rust/std/index.htmlhttps://notriddle.com/rustdoc-html-demo-5/sidebar-layout-rocket/tokio/index.html
## Motivation
This improves visual information density (the construct with the logo and crate name is *shorter* than the logo on its own, because it's not square) and navigation clarity (we can now see what clicking the Rust logo does, specifically).
Compare this with the layout at [Phoenix's Hexdocs] (which is what this proposal is closely based on), the old proposal on [Internals Discourse] (which always says "Rust standard library" in the sidebar, but doesn't do the side-by-side layout).
[Phoenix's Hexdocs]: https://hexdocs.pm/phoenix/1.7.7/overview.html
[Internals Discourse]: https://internals.rust-lang.org/t/poc-of-a-new-design-for-the-generated-rustdoc/11018
## Guide-level explanation
This PR cleans up some of the sidebar navigation.
It makes the logo in the desktop sidebar a bit smaller, and puts the crate name and version next to it (either beside it, or below it, depending on if there's space), making it clearer what clicking on it does: click the crate name to open the crate's home page. It also removes the Rust logo from non-official-Rust crates, again to make the navigation and supply chain clearer (since the crate name has been added, the logo is no longer necessary for navigation).
It adds a bit more clarifying information for lateral navigation. On items that don't add their own sidebar items, it just shows its siblings directly below the crate name and logo, but for other items, it shows "In crate alloc" instead of just "In alloc". It also shows the lateral navigation tools on module pages, making modules consistent with every other item.
## Drawbacks
While this actually takes up less screen real estate than the old layout on desktop, it takes up more HTML. It's also a bit more visually complex.
## Rationale and alternatives
I could do what the Internals POC did and keep the vertically stacked layout all the time, instead of doing a horizontal stack where possible. It would take up more screen real estate, though.
## Prior art
This design is lifted almost verbatim from Hexdocs. It seems to work for them. [`opentelemetry_process_propagator`], for example, has a long application name.
[`opentelemetry_process_propagator`]: https://hexdocs.pm/opentelemetry_process_propagator/OpentelemetryProcessPropagator.html
## Unresolved questions
Maybe we should encourage crate authors to include their own logo more often? It certainly helps give people a better sense of "place." This seems to be blocked on coming up with an API to do it without requiring them to host the file somewhere.
## Future possibilities
Beyond this, plenty of other changes could be made to improve the layout, like
* Fix things so that clicking an item in the sidebar doesn't cause it to scroll back to the top.
* The [Internals demo](https://utherii.github.io/new.html) does this right: clicking an item in the sidebar changes the content area, but the sidebar itself does not change. This is nice, because clicking is cheap and I can skim the opening few paragraphs while browsing.
* The layout of the docs sidebar causes trouble to implement this, because it's different on different pages, but at least fix this on the file browser.
* Come up with a less cluttered way to do disclosure. There's a lot of `[-]` on the page.
* We don't lack ideas to fix this one. We have *too many*.
* Do a better job of separating local navigation (vec::Vec links to vec::IntoIter) and the table of contents (vec::Vec links to vec::Vec::new).
* A possibility: add a Back arrow next to the "In [module]" header?
* Give readers more control of how much rustdoc shows them, and giving doc authors more control of how much it generates. Basically, https://github.com/rust-lang/rust/pull/115660 is great, let's do it too.
But those are mostly orthogonal, not future possibilities unlocked by this change.
Show more information when multiple `impl`s apply
- When there are `impl`s without type params, show only those (to avoid showing overly generic `impl`s).
```
error[E0283]: type annotations needed
--> $DIR/multiple-impl-apply.rs:34:9
|
LL | let y = x.into();
| ^ ---- type must be known at this point
|
note: multiple `impl`s satisfying `_: From<Baz>` found
--> $DIR/multiple-impl-apply.rs:14:1
|
LL | impl From<Baz> for Bar {
| ^^^^^^^^^^^^^^^^^^^^^^
...
LL | impl From<Baz> for Foo {
| ^^^^^^^^^^^^^^^^^^^^^^
= note: required for `Baz` to implement `Into<_>`
help: consider giving `y` an explicit type
|
LL | let y: /* Type */ = x.into();
| ++++++++++++
```
- Lower the importance of `T: Sized`, `T: WellFormed` and coercion errors, to prioritize more relevant errors. The pre-existing deduplication logic deals with hiding redundant errors better that way, and we show errors with more metadata that is useful to the user.
- Show `<SelfTy as Trait>::assoc_fn` suggestion in more cases.
```
error[E0790]: cannot call associated function on trait without specifying the corresponding `impl` type
--> $DIR/cross-return-site-inference.rs:38:16
|
LL | return Err(From::from("foo"));
| ^^^^^^^^^^ cannot call associated function of trait
|
help: use a fully-qualified path to a specific available implementation
|
LL | return Err(</* self type */ as From>::from("foo"));
| +++++++++++++++++++ +
```
Fix#88284.
