If it's a static candidate, then it's already implemented. Do not suggest
it a second time for implementing.

This reverts commit a6b5f95.

This patch adds test cases for AFIT, the majority of which are currently
expected to run as `check-fail`.

Co-authored-by: Michael Goulet <[email protected]>

- Add comment to some tests that will break when rust-lang#102745 is implemented
- Mark a test with known-bug
- Delete duplicate test

…errors

Add tests for static async functions in traits

This patch adds test cases for AFIT, the majority of which are currently expected to run as `check-fail`.

---

Note: I grabbed the cases from https://hackmd.io/SwRcXCiWQV-WRJ4BYs53fA

Also, I'm not sure if the `async-associated-types2` and `async-associated-types2-desugared` are correct, I modified them a bit from the examples in the HackMD.

…ns, r=cjgillot

Add suggestions for unsafe impl error codes

Adds suggestions for users to add `unsafe` to trait impls that should be `unsafe`, and remove `unsafe` from trait impls that do not require `unsafe`

With the folllowing code:

```rust
struct Foo {}

struct Bar {}

trait Safe {}

unsafe trait Unsafe {}

impl Safe for Foo {} // ok

impl Unsafe for Foo {} // E0200

unsafe impl Safe for Bar {} // E0199

unsafe impl Unsafe for Bar {} // ok

// omitted empty main fn
```

The current rustc output is:
```
error[E0199]: implementing the trait `Safe` is not unsafe
  --> e0200.rs:13:1
   |
13 | unsafe impl Safe for Bar {} // E0199
   | ^^^^^^^^^^^^^^^^^^^^^^^^^^^

error[E0200]: the trait `Unsafe` requires an `unsafe impl` declaration
  --> e0200.rs:11:1
   |
11 | impl Unsafe for Foo {} // E0200
   | ^^^^^^^^^^^^^^^^^^^^^^

error: aborting due to 2 previous errors

Some errors have detailed explanations: E0199, E0200.
For more information about an error, try `rustc --explain E0199`.
```

With this PR, the future rustc output would be:
```
error[E0199]: implementing the trait `Safe` is not unsafe
  --> ../../temp/e0200.rs:13:1
   |
13 | unsafe impl Safe for Bar {} // E0199
   | ^^^^^^^^^^^^^^^^^^^^^^^^^^^
   |
help: remove `unsafe` from this trait implementation
   |
13 - unsafe impl Safe for Bar {} // E0199
13 + impl Safe for Bar {} // E0199
   |

error[E0200]: the trait `Unsafe` requires an `unsafe impl` declaration
  --> ../../temp/e0200.rs:11:1
   |
11 | impl Unsafe for Foo {} // E0200
   | ^^^^^^^^^^^^^^^^^^^^^^
   |
   = note: the trait `Unsafe` enforces invariants that the compiler can't check. Review the trait documentation and make sure this implementation upholds those invariants before adding the `unsafe` keyword
help: add `unsafe` to this trait implementation
   |
11 | unsafe impl Unsafe for Foo {} // E0200
   | ++++++

error: aborting due to 2 previous errors

Some errors have detailed explanations: E0199, E0200.
For more information about an error, try `rustc --explain E0199`.
```

``@rustbot`` label +T-compiler +A-diagnostics +A-suggestion-diagnostics

…impl-block, r=notriddle

Fix unwanted merge of inline doc comments for impl blocks

Fixes rust-lang#102909.

We need this merge mechanism for inlined items but it's completely unwanted for impl blocks (at least the doc comments are, not the other attributes) since we want to keep what `cfg()` is put on the `pub use` or other attributes.

r? ``@notriddle``

…tic-candidates, r=wesleywiser

diagnostics: do not suggest static candidates as traits to import

If it's a static candidate, then it's already implemented. Do not suggest it a second time for implementing.

Partial fix for rust-lang#102354

…gillot

Don't carry MIR location in `ConstraintCategory::CallArgument`

It turns out that `ConstraintCategory::CallArgument` cannot just carry a MIR location in it, since we may bubble them up to totally different MIR bodies.

So instead, revert the commit a6b5f95, and instead just erase regions from the original `Option<Ty<'tcx>>` that it carried, so that it doesn't ICE with the changes in rust-lang#103220.

Best reviewed in parts -- the first is just a revert, and the second is where the meaningful changes happen.

Fixes rust-lang#103624