Add more suggestions to unexpected cfg names and values
This pull request adds more suggestion to unexpected cfg names and values diagnostics:
- it first adds a links to the [rustc unstable book](https://doc.rust-lang.org/nightly/unstable-book/compiler-flags/check-cfg.html) or the [Cargo reference](https://doc.rust-lang.org/nightly/cargo/reference/unstable.html#check-cfg), depending if rustc is invoked by Cargo
- it secondly adds a suggestion on how to expect the cfg name or value:
*excluding well known names and values*
- for Cargo: it suggest using a feature or `cargo:rust-check-cfg` in build script
- for rustc: it suggest using `--check-cfg` (with the correct invocation)
Those diagnostics improvements are directed towards enabling users to fix the issue if the previous suggestions weren't good enough.
r? `@petrochenkov`
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.
Add new simpler and more explicit syntax for check-cfg
<details>
<summary>
Old proposition (before the MCP)
</summary>
This PR adds a new simpler and more explicit syntax for check-cfg. It consist of two new form:
- `exhaustive(names, values)`
- `configure(name, "value1", "value2", ... "valueN")`
The preview forms `names(...)` and `values(...)` have implicit meaning that are not strait-forward. In particular `values(foo)`&`values(bar)` and `names(foo, bar)` are not equivalent which has created [some confusions](https://github.com/rust-lang/rust/pull/98080).
Also the `names()` and `values()` form are not clear either and again created some confusions where peoples believed that `values()`&`values(foo)` could be reduced to just `values(foo)`.
To fix that the two new forms are made to be explicit and simpler. See the table of correspondence:
- `names()` -> `exhaustive(names)`
- `values()` -> `exhaustive(values)`
- `names(foo)` -> `exhaustive(names)`&`configure(foo)`
- `values(foo)` -> `configure(foo)`
- `values(feat, "foo", "bar")` -> `configure(feat, "foo", "bar")`
- `values(foo)`&`values(bar)` -> `configure(foo, bar)`
- `names()`&`values()`&`values(my_cfg)` -> `exhaustive(names, values)`&`configure(my_cfg)`
Another benefits of the new syntax is that it allow for further options (like conditional checking for --cfg, currently always on) without syntax change.
The two previous forms are deprecated and will be removed once cargo and beta rustc have the necessary support.
</details>
This PR is the first part of the implementation of [MCP636 - Simplify and improve explicitness of the check-cfg syntax](https://github.com/rust-lang/compiler-team/issues/636).
## New `cfg` form
It introduces the new [`cfg` form](https://github.com/rust-lang/compiler-team/issues/636) and deprecate the other two:
```
rustc --check-cfg 'cfg(name1, ..., nameN, values("value1", "value2", ... "valueN"))'
```
## Default built-in names and values
It also changes the default for the built-in names and values checking.
- Built-in values checking would always be activated as long as a `--check-cfg` argument is present
- Built-in names checking would always be activated as long as a `--check-cfg` argument is present **unless** if any `cfg(any())` arg is passed
~~**Note: depends on https://github.com/rust-lang/rust/pull/111068 but is reviewable (last two commits)!**~~
Resolve https://github.com/rust-lang/compiler-team/issues/636
r? `@petrochenkov`
Suggest trait bounds for used associated type on type param
Fix#101351.
When an associated type on a type parameter is used, and the type parameter isn't constrained by the correct trait, suggest the appropriate trait bound:
```
error[E0220]: associated type `Associated` not found for `T`
--> file.rs:6:15
|
6 | field: T::Associated,
| ^^^^^^^^^^ there is a similarly named associated type `Associated` in the trait `Foo`
|
help: consider restricting type parameter `T`
|
5 | struct Generic<T: Foo> {
| +++++
```
When an associated type on a type parameter has a typo, suggest fixing
it:
```
error[E0220]: associated type `Baa` not found for `T`
--> $DIR/issue-55673.rs:9:8
|
LL | T::Baa: std::fmt::Debug,
| ^^^ there is a similarly named associated type `Bar` in the trait `Foo`
|
help: change the associated type name to use `Bar` from `Foo`
|
LL | T::Bar: std::fmt::Debug,
| ~~~
```
Fix#101351.
When an associated type on a type parameter is used, and the type
parameter isn't constrained by the correct trait, suggest the
appropriate trait bound:
```
error[E0220]: associated type `Associated` not found for `T`
--> file.rs:6:15
|
6 | field: T::Associated,
| ^^^^^^^^^^ there is a similarly named associated type `Associated` in the trait `Foo`
|
help: consider restricting type parameter `T`
|
5 | struct Generic<T: Foo> {
| +++++
```
When an associated type on a type parameter has a typo, suggest fixing
it:
```
error[E0220]: associated type `Baa` not found for `T`
--> $DIR/issue-55673.rs:9:8
|
LL | T::Baa: std::fmt::Debug,
| ^^^ there is a similarly named associated type `Bar` in the trait `Foo`
|
help: change the associated type name to use `Bar` from `Foo`
|
LL | T::Bar: std::fmt::Debug,
| ~~~
```
