llvm failed to generate code when trait_upcasting feature used

[mikialex]

I tried this code:

#![feature(trait_upcasting)]

pub trait A {}
pub trait B {}

pub trait C: A + B {}
impl<X: A + B> C for X {}

pub fn test<'a, T>(view: T) -> Option<&'a mut dyn B>
where
  T: IntoIterator<Item = &'a mut dyn B>,
{
  return Some(view.into_iter().next().unwrap());
}

fn main() {
  let mut a: Vec<Box<dyn C>> = Vec::new();
  test(a.iter_mut().map(|c| c.as_mut() as &mut dyn B));
}

I expected to see this happen: compile successfully

Instead, this happened: get a compile error:

Invalid InsertValueInst operands!
  %13 = insertvalue { {}*, [3 x i64]* } %12, i8* %11, 1, !dbg !170
in function _ZN6viewer6viewer10controller4test1t28_$u7b$$u7b$closure$u7d$$u7d$17h1000438316d202ffE
LLVM ERROR: Broken function found, compilation aborted!

Meta

rustc --version --verbose:

rustc 1.64.0-nightly (87588a2af 2022-07-13)
binary: rustc
commit-hash: 87588a2afd9ca903366f0deaf84d805f34469384
commit-date: 2022-07-13
host: x86_64-apple-darwin
release: 1.64.0-nightly
LLVM version: 14.0.6

no other backtrace logged

only debug build has this issue

[crlf0710]

Seems no longer panicks on today's playground: 1.65.0-nightly
(2022-08-16 86c6ebe)

https://play.rust-lang.org/?version=nightly&mode=debug&edition=2021&gist=a8cba42dddd847755877dd207aa83994

Is it worth bisecting what has changed in this month?

[crlf0710]

Did a roughly bisect on the pre-built nightly compilers:

fetching https://static.rust-lang.org/dist/2022-08-12/channel-rust-nightly-git-commit-hash.txt
nightly manifest 2022-08-12: 40 B / 40 B [======================================================] 100.00 % 100.29 KB/s converted 2022-08-12 to 20ffea6938b5839c390252e07940b99e3b6a889a

fetching https://static.rust-lang.org/dist/2022-08-13/channel-rust-nightly-git-commit-hash.txt
nightly manifest 2022-08-13: 40 B / 40 B [======================================================] 100.00 % 117.20 KB/s converted 2022-08-13 to f22819bcce4abaff7d1246a56eec493418f9f4ee

Seems it got fixed between 20ffea6..f22819b range. Didn't build each of the commits landed between them, but since the llvm 15 update is there, it is highly likely the cure ...