Panic 'entered unreachable code' with nightly rustc

[MForster]

Rust analyzer panics when using nightly rustc:

rust-analyzer version: 0.3.1248-standalone
rustc version: rustc 1.63.0-nightly (fee3a45 2022-06-05)

I've confirmed that it works with stable rustc.

thread 'before' panicked at 'internal error: entered unreachable code', crates/proc-macro-srv/src/abis/abi_1_63/proc_macro/bridge/mod.rs:261:5
stack backtrace:
   0: rust_begin_unwind
             at /rustc/a55dd71d5fb0ec5a6a3a9e8c27b2127ba491ce52/library/std/src/panicking.rs:584:5
   1: core::panicking::panic_fmt
             at /rustc/a55dd71d5fb0ec5a6a3a9e8c27b2127ba491ce52/library/core/src/panicking.rs:142:14
   2: core::panicking::panic
             at /rustc/a55dd71d5fb0ec5a6a3a9e8c27b2127ba491ce52/library/core/src/panicking.rs:48:5
   3: <proc_macro_srv::abis::abi_1_63::proc_macro::bridge::api_tags::Method as proc_macro_srv::abis::abi_1_63::proc_macro::bridge::rpc::DecodeMut<S>>::decode
   4: <proc_macro_srv::abis::abi_1_63::proc_macro::bridge::server::Dispatcher<proc_macro_srv::abis::abi_1_63::proc_macro::bridge::server::MarkedTypes<S>> as proc_macro_srv::abis::abi_1_63::proc_macro::bridge::server::DispatcherTrait>::dispatch
   5: <proc_macro_srv::abis::abi_1_63::proc_macro::bridge::closure::Closure<A,R> as core::convert::From<&mut F>>::from::call
   6: proc_macro::bridge::closure::Closure<A,R>::call
             at /rustc/fee3a459dd6aba8e34a5b99f0fbcb4218a1e2401/library/proc_macro/src/bridge/closure.rs:30:18
   7: proc_macro::bridge::client::Span::call_site::{{closure}}
             at /rustc/fee3a459dd6aba8e34a5b99f0fbcb4218a1e2401/library/proc_macro/src/bridge/client.rs:263:27
   8: proc_macro::bridge::client::<impl proc_macro::bridge::Bridge>::with::{{closure}}
             at /rustc/fee3a459dd6aba8e34a5b99f0fbcb4218a1e2401/library/proc_macro/src/bridge/client.rs:355:47
   9: proc_macro::bridge::client::BridgeState::with::{{closure}}::{{closure}}
             at /rustc/fee3a459dd6aba8e34a5b99f0fbcb4218a1e2401/library/proc_macro/src/bridge/client.rs:312:17
  10: proc_macro::bridge::scoped_cell::ScopedCell<T>::replace
             at /rustc/fee3a459dd6aba8e34a5b99f0fbcb4218a1e2401/library/proc_macro/src/bridge/scoped_cell.rs:74:9
  11: proc_macro::bridge::client::BridgeState::with::{{closure}}
             at /rustc/fee3a459dd6aba8e34a5b99f0fbcb4218a1e2401/library/proc_macro/src/bridge/client.rs:310:13
  12: std::thread::local::LocalKey<T>::try_with
             at /rustc/fee3a459dd6aba8e34a5b99f0fbcb4218a1e2401/library/std/src/thread/local.rs:445:16
  13: std::thread::local::LocalKey<T>::with
             at /rustc/fee3a459dd6aba8e34a5b99f0fbcb4218a1e2401/library/std/src/thread/local.rs:421:9
  14: proc_macro::bridge::client::BridgeState::with
             at /rustc/fee3a459dd6aba8e34a5b99f0fbcb4218a1e2401/library/proc_macro/src/bridge/client.rs:309:9
  15: proc_macro::bridge::client::<impl proc_macro::bridge::Bridge>::with
             at /rustc/fee3a459dd6aba8e34a5b99f0fbcb4218a1e2401/library/proc_macro/src/bridge/client.rs:348:9
  16: proc_macro::bridge::client::Span::call_site
             at /rustc/fee3a459dd6aba8e34a5b99f0fbcb4218a1e2401/library/proc_macro/src/bridge/client.rs:256:17
  17: proc_macro::Span::call_site
             at /rustc/fee3a459dd6aba8e34a5b99f0fbcb4218a1e2401/library/proc_macro/src/lib.rs:347:14
  18: rustversion::expand::try_cfg
             at /home/mforster/.cargo/registry/src/github.com-1ecc6299db9ec823/rustversion-1.0.9/src/expand.rs:12:45
  19: rustversion::expand::cfg
             at /home/mforster/.cargo/registry/src/github.com-1ecc6299db9ec823/rustversion-1.0.9/src/expand.rs:8:5
  20: rustversion::before
             at /home/mforster/.cargo/registry/src/github.com-1ecc6299db9ec823/rustversion-1.0.9/src/lib.rs:209:5
  21: core::ops::function::Fn::call
             at /rustc/fee3a459dd6aba8e34a5b99f0fbcb4218a1e2401/library/core/src/ops/function.rs:77:5
  22: proc_macro::bridge::client::Client<(proc_macro::TokenStream,proc_macro::TokenStream),proc_macro::TokenStream>::expand2::{{closure}}::{{closure}}
             at /rustc/fee3a459dd6aba8e34a5b99f0fbcb4218a1e2401/library/proc_macro/src/bridge/client.rs:453:21
  23: proc_macro::bridge::client::run_client::{{closure}}::{{closure}}
             at /rustc/fee3a459dd6aba8e34a5b99f0fbcb4218a1e2401/library/proc_macro/src/bridge/client.rs:407:26
  24: proc_macro::bridge::scoped_cell::ScopedCell<T>::set::{{closure}}
             at /rustc/fee3a459dd6aba8e34a5b99f0fbcb4218a1e2401/library/proc_macro/src/bridge/scoped_cell.rs:79:33
  25: proc_macro::bridge::scoped_cell::ScopedCell<T>::replace
             at /rustc/fee3a459dd6aba8e34a5b99f0fbcb4218a1e2401/library/proc_macro/src/bridge/scoped_cell.rs:74:9
  26: proc_macro::bridge::scoped_cell::ScopedCell<T>::set
             at /rustc/fee3a459dd6aba8e34a5b99f0fbcb4218a1e2401/library/proc_macro/src/bridge/scoped_cell.rs:79:9
  27: proc_macro::bridge::client::<impl proc_macro::bridge::Bridge>::enter::{{closure}}
             at /rustc/fee3a459dd6aba8e34a5b99f0fbcb4218a1e2401/library/proc_macro/src/bridge/client.rs:344:35
  28: std::thread::local::LocalKey<T>::try_with
             at /rustc/fee3a459dd6aba8e34a5b99f0fbcb4218a1e2401/library/std/src/thread/local.rs:445:16
  29: std::thread::local::LocalKey<T>::with
             at /rustc/fee3a459dd6aba8e34a5b99f0fbcb4218a1e2401/library/std/src/thread/local.rs:421:9
  30: proc_macro::bridge::client::<impl proc_macro::bridge::Bridge>::enter
             at /rustc/fee3a459dd6aba8e34a5b99f0fbcb4218a1e2401/library/proc_macro/src/bridge/client.rs:344:9
  31: proc_macro::bridge::client::run_client::{{closure}}
             at /rustc/fee3a459dd6aba8e34a5b99f0fbcb4218a1e2401/library/proc_macro/src/bridge/client.rs:400:9
  32: <core::panic::unwind_safe::AssertUnwindSafe<F> as core::ops::function::FnOnce<()>>::call_once
             at /rustc/fee3a459dd6aba8e34a5b99f0fbcb4218a1e2401/library/core/src/panic/unwind_safe.rs:271:9
  33: std::panicking::try::do_call
             at /rustc/fee3a459dd6aba8e34a5b99f0fbcb4218a1e2401/library/std/src/panicking.rs:492:40
  34: __rust_try
  35: std::panicking::try
             at /rustc/fee3a459dd6aba8e34a5b99f0fbcb4218a1e2401/library/std/src/panicking.rs:456:19
  36: std::panic::catch_unwind
             at /rustc/fee3a459dd6aba8e34a5b99f0fbcb4218a1e2401/library/std/src/panic.rs:137:14
  37: proc_macro::bridge::client::run_client
             at /rustc/fee3a459dd6aba8e34a5b99f0fbcb4218a1e2401/library/proc_macro/src/bridge/client.rs:399:5
  38: proc_macro::bridge::client::Client<(proc_macro::TokenStream,proc_macro::TokenStream),proc_macro::TokenStream>::expand2::{{closure}}
             at /rustc/fee3a459dd6aba8e34a5b99f0fbcb4218a1e2401/library/proc_macro/src/bridge/client.rs:452:17
  39: proc_macro::bridge::selfless_reify::reify_to_extern_c_fn_hrt_bridge::wrapper
             at /rustc/fee3a459dd6aba8e34a5b99f0fbcb4218a1e2401/library/proc_macro/src/bridge/selfless_reify.rs:64:17
  40: proc_macro_srv::abis::abi_1_63::proc_macro::bridge::server::run_server
  41: proc_macro_srv::abis::abi_1_63::proc_macro::bridge::server::<impl proc_macro_srv::abis::abi_1_63::proc_macro::bridge::client::Client<(proc_macro_srv::abis::abi_1_63::proc_macro::TokenStream,proc_macro_srv::abis::abi_1_63::proc_macro::TokenStream),proc_macro_srv::abis::abi_1_63::proc_macro::TokenStream>>::run
  42: proc_macro_srv::abis::abi_1_63::Abi::expand
  43: proc_macro_srv::dylib::Expander::expand
note: Some details are omitted, run with `RUST_BACKTRACE=full` for a verbose backtrace.

[lnicola]

You need to switch to an older or a newer (end of July? I don't remember) nightly.

[MForster]

Confirmed that this works with rustc 1.66.0-nightly (6e95b6da8 2022-10-22).

I could have figured this out myself :-). A nicer error message would have been nice...

[lnicola]

More recent nightlies should always (terms and conditions apply) be compatible with RA: https://fasterthanli.me/articles/proc-macro-support-in-rust-analyzer-for-nightly-rustc-versions.