Auto merge of #116447 - oli-obk:gen_fn, r=compiler-errors

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

1 files changed, 3 insertions, 0 deletions

diff --git a/compiler/rustc_codegen_ssa/src/debuginfo/type_names.rs b/compiler/rustc_codegen_ssa/src/debuginfo/type_names.rs
index 5900c764073..1a85eb8dd79 100644
--- a/compiler/rustc_codegen_ssa/src/debuginfo/type_names.rs
+++ b/compiler/rustc_codegen_ssa/src/debuginfo/type_names.rs
@@ -560,6 +560,9 @@ pub fn push_item_name(tcx: TyCtxt<'_>, def_id: DefId, qualified: bool, output: &
 
 fn coroutine_kind_label(coroutine_kind: Option<CoroutineKind>) -> &'static str {
     match coroutine_kind {
+        Some(CoroutineKind::Gen(CoroutineSource::Block)) => "gen_block",
+        Some(CoroutineKind::Gen(CoroutineSource::Closure)) => "gen_closure",
+        Some(CoroutineKind::Gen(CoroutineSource::Fn)) => "gen_fn",
         Some(CoroutineKind::Async(CoroutineSource::Block)) => "async_block",
         Some(CoroutineKind::Async(CoroutineSource::Closure)) => "async_closure",
         Some(CoroutineKind::Async(CoroutineSource::Fn)) => "async_fn",