Unnamed union fields with enums are checked for, but if `find_field`
causes an ICE then the compiler won't get to that point.

Signed-off-by: David Wood <david@davidtw.co>

Signed-off-by: David Wood <david@davidtw.co>

…types_defined_by`

Instead, when we're collecting opaques for associated items, we choose the right collection mode depending on whether we're collecting for an associated item of a trait impl or not.

… r=pnkfelix

Limit the number of names and values in check-cfg diagnostics

The Rust for Linux [feedback](rust-lang#82450 (comment)) to the check-cfg Call for Testing, revealed a weakness in the check-cfg. They are unbounded and in the case RfL they have ~20k cfgs and having them printed (even once) is unbearable.

This PR limits it to 35 (28 rustc well known + `feature` + `docsrs` + 5 custom) which feels like a good middle ground for regular users (i.e. Cargo users).

When it goes over that limit print the N first with " and X more".

``@rustbot`` label +F-check-cfg

…r=pnkfelix

errors: share `SilentEmitter` between rustc and rustfmt

Fixes rust-lang/rustfmt#6082.

Shares the `SilentEmitter` between rustc and rustfmt, and gives it a fallback bundle (since it can emit diagnostics in some contexts).

…li-obk

Hint user to update nightly on ICEs produced from outdated nightly

This is a conservative best-effort approach to detect a potentially outdated nightly; it will fallback to the regular ICE-reporting if any of the following cases are true:
- Channel is not nightly
- Version information is not available
- Version date is not parseable as a YYYY-MM-DD or is missing
- System time is at least 36 hours ahead of the user's nightly release datetime.
- Any internal features are used.

Note that I'm not sure how to make a test for this: I tested this manually by `CFG_VER_DATE="2020-02-02" ./x build library --stage 1`, and also changing the channel detection in `rustc_driver_impl` from `Some("nightly")` to `Some("nightly" | "dev")`, and then running `rustc +stage1 test.rs -Ztreat-err-as-bug=1` with a non-existent `test.rs`.

<img width="1145" alt="Screenshot 2024-02-27 at 01 12 28" src="https://github.com/rust-lang/rust/assets/39484203/eff6af2e-4b19-4a70-af57-cd739ecf0e84">

Closes rust-lang#118832.

only compare ambiguity item that have hard error

Fixes rust-lang#121760

An easy fix, r? ``@petrochenkov``

…ochenkov

add test for rust-lang#78894 rust-lang#71450

fixes rust-lang#78894
fixes rust-lang#71450

…nkov

hir_analysis: enums return `None` in `find_field`

Fixes rust-lang#121757.

Unnamed union fields with enums are checked for, but if `find_field` causes an ICE then the compiler won't get to that point.

…th, r=bjorn3

Fix duplicated path in the "not found dylib" error

While working on the gcc backend, I couldn't figure out why I had this error:

```
error: couldn't load codegen backend /checkout/compiler/rustc_codegen_gcc/target/release/librustc_codegen_gcc.so/checkout/compiler/rustc_codegen_gcc/target/release/librustc_codegen_gcc.so: cannot open shared object file: No such file or directory
```

As you can see, the path is duplicated for some reason. After investigating a bit more, I realized that `libloading::Error::LoadLibraryExW` starts with the path of the not found dylib, making it appear twice in our error afterward (because we do render it like this: `{path}{err}`, and since the `err` starts with the path...).

Thanks to `````@bjorn3````` for linking me to rust-lang#121392. :)

…_by_queries, r=compiler-errors

Merge impl_trait_in_assoc_types_defined_by query back into `opaque_types_defined_by`

Instead, when we're collecting opaques for associated items, we choose the right collection mode depending on whether we're collecting for an associated item of a trait impl or not.

r? ```@compiler-errors```

follow up to rust-lang#121838