This environment variable should always be set by bootstrap in
`rustc_llvm_env`. The fallback is quite ugly and complicated, so
removing it is nice.

Now that we're using a type folder, the arguments in predicates are
processed automatically - we don't need to descend manually.

We also want to keep projection clauses around, and this does so.

Fix rust-lang#123442

…lubby789

Require LLVM_CONFIG to be set in rustc_llvm/build.rs

This environment variable should always be set by bootstrap in `rustc_llvm_env`. The fallback is quite ugly and complicated, so removing it is nice.

https://github.com/rust-lang/rust/blob/bf71daedc29e7a240261acd1516378047e311a6f/src/bootstrap/src/core/build_steps/compile.rs#L1166

I tried finding when this was added in git history, but it pointed all the way to "add build scripts" at which point I stopped digging more. This has always been here.

cc `@nikic` `@cuviper` in case you happen to be aware of a deeper reason behind this

r? bootstrap

MSVC targets should use COFF as their archive format

While adding support for Arm64EC I ran into an issue where the standard library's rlib was missing the "EC Symbol Table" which is required for the MSVC linker to find import library symbols (generated by Rust's `raw-dylib` feature) when building for EC.

The root cause of the issue is that LLVM only generated symbol tables (including the EC Symbol Table) if the `ArchiveKind` is `COFF`, but the MSVC targets didn't set their archive format, so it was defaulting to GNU.

explaining `DefKind::Field`

…ements, r=wesleywiser

Improve cfg and check-cfg configuration

This PR improves cfg and check-cfg configuration by:
 1. Extracting both logic under a common module (to improve the connection between the two)
 2. Adding more documentation, in particular some steps when adding a new cfg

I also added my-self as mention in our triagebot conf for the new module.

Inspired by rust-lang#123411 (comment)

CFI: Don't rewrite ty::Dynamic directly

Now that we're using a type folder, the arguments in predicates are processed automatically - we don't need to descend manually.

We also want to keep projection clauses around, and this does so.

r? `@compiler-errors`

…errors

Do not ICE when calling incorrectly defined `transmute` intrinsic

Fix rust-lang#123442

…ler-errors

Hide async_gen_internals from standard library documentation

These are from rust-lang#118420. It doesn't appear that there is any intention to ever make these APIs available to user code. These are just conveniences meant for the compiler's implementation of `async gen`. I don't think having them featured in documentation in <https://doc.rust-lang.org/1.77.1/core/task/enum.Poll.html> is appropriate.

![image](https://github.com/rust-lang/rust/assets/1940490/0a8ae90d-5c83-4ab1-b08a-50bad2433d69)