Unknown ICE

[korken89]

Hi, unfortunately I was not able to reprodue this ICE, but I'll provide the dump I got in case you can do something with it.

thread 'rustc' panicked at 'called `Option::unwrap()` on a `None` value', compiler/rustc_metadata/src/rmeta/decoder.rs:1565:75
note: run with `RUST_BACKTRACE=1` environment variable to display a backtrace
error: internal compiler error: unexpected panic
note: the compiler unexpectedly panicked. this is a bug.
note: we would appreciate a bug report: https://github.com/rust-lang/rust/issues/new?labels=C-bug%2C+I-ICE%2C+T-compiler&template=ice.md
note: rustc 1.50.0-nightly (3d6705aa5 2020-12-07) running on x86_64-unknown-linux-gnu
note: compiler flags: -C embed-bitcode=no -C debuginfo=2 -C incremental --crate-type lib
note: some of the compiler flags provided by cargo are hidden
query stack during panic:
#0 [analysis] running analysis passes on this crate
end of query stack

[dmit]

#79721 has the fix for this, waiting to be merged. The workaround meanwhile is to cargo clean the incremental cache and rebuild.

[camelid]

Actually I believe this is a duplicate of #79783.