ICE when reusing `syn::Error` stored in static `LazyLock` across multiple proc macro invocations

[mookums]

Code

/// proc-macro crate lib.rs
use proc_macro::TokenStream;
use proc_macro2::Span;
use quote::quote;
use std::sync::LazyLock;
use syn::Error;

#[derive(Debug)]
struct FallibleError;

impl std::fmt::Display for FallibleError {
    fn fmt(&self, f: &mut std::fmt::Formatter<'_>) -> std::fmt::Result {
        write!(f, "Fallible Error")
    }
}

fn fallible_function() -> Result<(), FallibleError> {
    Err(FallibleError)
}

static SHARED: LazyLock<Result<(), Error>> = LazyLock::new(|| {
    fallible_function().map_err(|e| Error::new(Span::call_site(), e.to_string()))?;
    Ok(())
});

#[proc_macro]
pub fn trigger_ice(_input: TokenStream) -> TokenStream {
    match SHARED.as_ref() {
        Ok(_) => quote! { fn it_worked() {} }.into(),
        Err(e) => e.to_compile_error().into(),
    }
}

/// main.rs
use minimal_ice_macro::trigger_ice;

fn helper1() {
    trigger_ice!();
}

fn helper2() {
    trigger_ice!();
}

fn main() {
    helper1();
    helper2();
}

Meta

rustc --version --verbose:

rustc 1.91.1 (ed61e7d7e 2025-11-07)
binary: rustc
commit-hash: ed61e7d7e242494fb7057f2657300d9e77bb4fcb
commit-date: 2025-11-07
host: x86_64-unknown-linux-gnu
release: 1.91.1
LLVM version: 21.1.2

Error output

   Compiling minimal_ice v0.1.0 (/home/muki/Git/mookums/minimal_ice/minimal_ice)
error: Fallible Error
 --> minimal_ice/src/main.rs:4:5
  |
4 |     trigger_ice!();
  |     ^^^^^^^^^^^^^^
  |
  = note: this error originates in the macro `trigger_ice` (in Nightly builds, run with -Z macro-backtrace for more info)


thread 'rustc' (17226) panicked at /rustc-dev/ed61e7d7e242494fb7057f2657300d9e77bb4fcb/compiler/rustc_proc_macro/../../library/proc_macro/src/bridge/handle.rs:73:19:
use-after-free in `proc_macro` handle
stack backtrace:
   0: __rustc::rust_begin_unwind
   1: core::panicking::panic_fmt
   2: core::option::expect_failed
   3: <rustc_proc_macro::bridge::TokenTree<rustc_proc_macro::bridge::Marked<rustc_ast::tokenstream::TokenStream, rustc_proc_macro::bridge::client::TokenStream>, rustc_proc_macro::bridge::Marked<rustc_span::span_encoding::Span, rustc_proc_macro::bridge::client::Span>, rustc_proc_macro::bridge::Marked<rustc_span::symbol::Symbol, rustc_proc_macro::bridge::symbol::Symbol>> as rustc_proc_macro::bridge::rpc::DecodeMut<rustc_proc_macro::bridge::server::HandleStore<rustc_proc_macro::bridge::server::MarkedTypes<rustc_expand::proc_macro_server::Rustc>>>>::decode
   4: <rustc_proc_macro::bridge::server::Dispatcher<rustc_proc_macro::bridge::server::MarkedTypes<rustc_expand::proc_macro_server::Rustc>> as rustc_proc_macro::bridge::server::DispatcherTrait>::dispatch
   5: <rustc_proc_macro::bridge::closure::Closure<_, _> as core::convert::From<&mut _>>::from::call::<rustc_proc_macro::bridge::buffer::Buffer, rustc_proc_macro::bridge::buffer::Buffer, <rustc_proc_macro::bridge::server::SameThread as rustc_proc_macro::bridge::server::ExecutionStrategy>::run_bridge_and_client<rustc_proc_macro::bridge::server::Dispatcher<rustc_proc_macro::bridge::server::MarkedTypes<rustc_expand::proc_macro_server::Rustc>>>::{closure#0}>
   6: proc_macro::bridge::closure::Closure<A,R>::call
             at /rustc/ed61e7d7e242494fb7057f2657300d9e77bb4fcb/library/proc_macro/src/bridge/closure.rs:30:18
   7: proc_macro::bridge::client::TokenStream::from_token_tree::{{closure}}
             at /rustc/ed61e7d7e242494fb7057f2657300d9e77bb4fcb/library/proc_macro/src/bridge/client.rs:149:43
   8: proc_macro::bridge::client::Bridge::with::{{closure}}
             at /rustc/ed61e7d7e242494fb7057f2657300d9e77bb4fcb/library/proc_macro/src/bridge/client.rs:227:13
   9: proc_macro::bridge::client::state::with
             at /rustc/ed61e7d7e242494fb7057f2657300d9e77bb4fcb/library/proc_macro/src/bridge/client.rs:216:9
  10: proc_macro::bridge::client::Bridge::with
             at /rustc/ed61e7d7e242494fb7057f2657300d9e77bb4fcb/library/proc_macro/src/bridge/client.rs:222:9
  11: proc_macro::bridge::client::TokenStream::from_token_tree
             at /rustc/ed61e7d7e242494fb7057f2657300d9e77bb4fcb/library/proc_macro/src/bridge/client.rs:142:17
  12: <proc_macro::TokenStream as core::convert::From<proc_macro::TokenTree>>::from
             at /rustc/ed61e7d7e242494fb7057f2657300d9e77bb4fcb/library/proc_macro/src/lib.rs:258:26
  13: <proc_macro2::imp::TokenStream as core::convert::From<proc_macro2::TokenTree>>::from
  14: <proc_macro2::TokenStream as core::convert::From<proc_macro2::TokenTree>>::from
  15: syn::error::ErrorMessage::to_compile_error
  16: syn::error::Error::to_compile_error
  17: minimal_ice_macro::trigger_ice
  18: core::ops::function::Fn::call
  19: proc_macro::bridge::client::Client<proc_macro::TokenStream,proc_macro::TokenStream>::expand1::{{closure}}::{{closure}}
  20: proc_macro::bridge::client::run_client::{{closure}}::{{closure}}
  21: proc_macro::bridge::client::state::set
  22: proc_macro::bridge::client::run_client::{{closure}}
  23: <core::panic::unwind_safe::AssertUnwindSafe<F> as core::ops::function::FnOnce<()>>::call_once
  24: std::panicking::catch_unwind::do_call
  25: __rust_try
  26: proc_macro::bridge::client::run_client
  27: proc_macro::bridge::client::Client<proc_macro::TokenStream,proc_macro::TokenStream>::expand1::{{closure}}
  28: proc_macro::bridge::selfless_reify::reify_to_extern_c_fn_hrt_bridge::wrapper
  29: <rustc_proc_macro::bridge::server::MaybeCrossThread<rustc_expand::proc_macro::MessagePipe<rustc_proc_macro::bridge::buffer::Buffer>> as rustc_proc_macro::bridge::server::ExecutionStrategy>::run_bridge_and_client::<rustc_proc_macro::bridge::server::Dispatcher<rustc_proc_macro::bridge::server::MarkedTypes<rustc_expand::proc_macro_server::Rustc>>>
  30: <rustc_proc_macro::bridge::client::Client<rustc_proc_macro::TokenStream, rustc_proc_macro::TokenStream>>::run::<rustc_expand::proc_macro_server::Rustc, rustc_proc_macro::bridge::server::MaybeCrossThread<rustc_expand::proc_macro::MessagePipe<rustc_proc_macro::bridge::buffer::Buffer>>>
  31: <rustc_expand::proc_macro::BangProcMacro as rustc_expand::base::BangProcMacro>::expand
  32: <rustc_expand::expand::MacroExpander>::fully_expand_fragment
  33: <rustc_expand::expand::MacroExpander>::expand_crate
  34: rustc_interface::passes::configure_and_expand
  35: rustc_interface::passes::resolver_for_lowering_raw
      [... omitted 2 frames ...]
  36: rustc_interface::passes::create_and_enter_global_ctxt::<core::option::Option<rustc_interface::queries::Linker>, rustc_driver_impl::run_compiler::{closure#0}::{closure#2}>::{closure#2}::{closure#0}
  37: rustc_interface::interface::run_compiler::<(), rustc_driver_impl::run_compiler::{closure#0}>::{closure#1}
note: Some details are omitted, run with `RUST_BACKTRACE=full` for a verbose backtrace.

error: 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 1.91.1 (ed61e7d7e 2025-11-07) running on x86_64-unknown-linux-gnu

note: compiler flags: --crate-type bin -C embed-bitcode=no -C debuginfo=2 -C incremental=[REDACTED]

note: some of the compiler flags provided by cargo are hidden

query stack during panic:
#0 [resolver_for_lowering_raw] getting the resolver for lowering
end of query stack
error: proc macro panicked
 --> minimal_ice/src/main.rs:8:5
  |
8 |     trigger_ice!();
  |     ^^^^^^^^^^^^^^
  |
  = help: message: use-after-free in `proc_macro` handle

error: could not compile `minimal_ice` (bin "minimal_ice") due to 2 previous errors

Backtrace

   Compiling minimal_ice v0.1.0 (/home/muki/Git/mookums/minimal_ice/minimal_ice)
error: Fallible Error
 --> minimal_ice/src/main.rs:4:5
  |
4 |     trigger_ice!();
  |     ^^^^^^^^^^^^^^
  |
  = note: this error originates in the macro `trigger_ice` (in Nightly builds, run with -Z macro-backtrace for more info)


thread 'rustc' (17453) panicked at /rustc-dev/ed61e7d7e242494fb7057f2657300d9e77bb4fcb/compiler/rustc_proc_macro/../../library/proc_macro/src/bridge/handle.rs:73:19:
use-after-free in `proc_macro` handle
stack backtrace:
   0:     0x7ffff4a4c903 - <std::sys::backtrace::BacktraceLock::print::DisplayBacktrace as core::fmt::Display>::fmt::haa87a551a4affa55
   1:     0x7ffff5201bd8 - core::fmt::write::h80461e1e45e4fdd2
   2:     0x7ffff6805b6f - std::io::Write::write_fmt::h6e6c69b2d6337d9b
   3:     0x7ffff4a11dc2 - std::sys::backtrace::BacktraceLock::print::hf67a46baa621998e
   4:     0x7ffff4a17d19 - std::panicking::default_hook::{{closure}}::h391aa815d5e47ec8
   5:     0x7ffff4a17843 - std::panicking::default_hook::hd6fdcf2489bb807d
   6:     0x7ffff39fe9a7 - std[868c2b82e02752c5]::panicking::update_hook::<alloc[2f8cfedda7e895ee]::boxed::Box<rustc_driver_impl[8c00ca3c7ff43d1e]::install_ice_hook::{closure#1}>>::{closure#0}
   7:     0x7ffff4a1813f - std::panicking::panic_with_hook::h185ddfb86bf14d73
   8:     0x7ffff4a17efa - std::panicking::panic_handler::{{closure}}::had89ddd01b6112c9
   9:     0x7ffff4a11ef9 - std::sys::backtrace::__rust_end_short_backtrace::h5d0fc36eef7265ea
  10:     0x7ffff49f286d - __rustc[eb8946e36839644a]::rust_begin_unwind
  11:     0x7ffff10e7b00 - core::panicking::panic_fmt::h92c8e5abe71dd8d1
  12:     0x7ffff246581b - core::option::expect_failed::h1729d0bd73171c50
  13:     0x7ffff3ab458c - <rustc_proc_macro[4c932ddccfb31674]::bridge::TokenTree<rustc_proc_macro[4c932ddccfb31674]::bridge::Marked<rustc_ast[587ebf2c73052b65]::tokenstream::TokenStream, rustc_proc_macro[4c932ddccfb31674]::bridge::client::TokenStream>, rustc_proc_macro[4c932ddccfb31674]::bridge::Marked<rustc_span[708dd8ee61ad0c72]::span_encoding::Span, rustc_proc_macro[4c932ddccfb31674]::bridge::client::Span>, rustc_proc_macro[4c932ddccfb31674]::bridge::Marked<rustc_span[708dd8ee61ad0c72]::symbol::Symbol, rustc_proc_macro[4c932ddccfb31674]::bridge::symbol::Symbol>> as rustc_proc_macro[4c932ddccfb31674]::bridge::rpc::DecodeMut<rustc_proc_macro[4c932ddccfb31674]::bridge::server::HandleStore<rustc_proc_macro[4c932ddccfb31674]::bridge::server::MarkedTypes<rustc_expand[5a74fa380dd05054]::proc_macro_server::Rustc>>>>::decode
  14:     0x7ffff6111fdd - <rustc_proc_macro[4c932ddccfb31674]::bridge::server::Dispatcher<rustc_proc_macro[4c932ddccfb31674]::bridge::server::MarkedTypes<rustc_expand[5a74fa380dd05054]::proc_macro_server::Rustc>> as rustc_proc_macro[4c932ddccfb31674]::bridglazylocke::server::DispatcherTrait>::dispatch
  15:     0x7ffff610ed70 - <rustc_proc_macro[4c932ddccfb31674]::bridge::closure::Closure<_, _> as core[3960b0be9a8ab2fb]::convert::From<&mut _>>::from::call::<rustc_proc_macro[4c932ddccfb31674]::bridge::buffer::Buffer, rustc_proc_macro[4c932ddccfb31674]::bridge::buffer::Buffer, <rustc_proc_macro[4c932ddccfb31674]::bridge::server::SameThread as rustc_proc_macro[4c932ddccfb31674]::bridge::server::ExecutionStrategy>::run_bridge_and_client<rustc_proc_macro[4c932ddccfb31674]::bridge::server::Dispatcher<rustc_proc_macro[4c932ddccfb31674]::bridge::server::MarkedTypes<rustc_expand[5a74fa380dd05054]::proc_macro_server::Rustc>>>::{closure#0}>
  16:     0x7fffe4ea6307 - proc_macro::bridge::closure::Closure<A,R>::call::h7f8ca987bf7b2de0
                               at /rustc/ed61e7d7e242494fb7057f2657300d9e77bb4fcb/library/proc_macro/src/bridge/closure.rs:30:18
  17:     0x7fffe4ea6307 - proc_macro::bridge::client::TokenStream::from_token_tree::{{closure}}::h9aaef0ecff856ad8
                               at /rustc/ed61e7d7e242494fb7057f2657300d9e77bb4fcb/library/proc_macro/src/bridge/client.rs:149:43
  18:     0x7fffe4ea6307 - proc_macro::bridge::client::Bridge::with::{{closure}}::he660f1a130e0d84c
                               at /rustc/ed61e7d7e242494fb7057f2657300d9e77bb4fcb/library/proc_macro/src/bridge/client.rs:227:13
  19:     0x7fffe4ea6307 - proc_macro::bridge::client::state::with::h4e6ddc6a122883ec
                               at /rustc/ed61e7d7e242494fb7057f2657300d9e77bb4fcb/library/proc_macro/src/bridge/client.rs:216:9
  20:     0x7fffe4ea6307 - proc_macro::bridge::client::Bridge::with::h4b6dc168a192463a
                               at /rustc/ed61e7d7e242494fb7057f2657300d9e77bb4fcb/library/proc_macro/src/bridge/client.rs:222:9
  21:     0x7fffe4ea6307 - proc_macro::bridge::client::TokenStream::from_token_tree::h7d64daa50e0caa5d
                               at /rustc/ed61e7d7e242494fb7057f2657300d9e77bb4fcb/library/proc_macro/src/bridge/client.rs:142:17
  22:     0x7fffe4ea6307 - <proc_macro::TokenStream as core::convert::From<proc_macro::TokenTree>>::from::hd5452b19f706845e
                               at /rustc/ed61e7d7e242494fb7057f2657300d9e77bb4fcb/library/proc_macro/src/lib.rs:258:26
  23:     0x7fffe4e995d0 - <proc_macro2::imp::TokenStream as core::convert::From<proc_macro2::TokenTree>>::from::he49f34a67fa34f94
  24:     0x7fffe4e9b679 - <proc_macro2::TokenStream as core::convert::From<proc_macro2::TokenTree>>::from::hd36ed5d645084d83
  25:     0x7fffe4e92b9b - syn::error::ErrorMessage::to_compile_error::h8fc7a9288d7d4790
  26:     0x7fffe4e92d5a - syn::error::Error::to_compile_error::h85253c9c68396ace
  27:     0x7fffe4e90012 - minimal_ice_macro::trigger_ice::hf9e470ced26765e7
  28:     0x7fffe4e9084e - core::ops::function::Fn::call::h80c0872a42c91b59
  29:     0x7fffe4e92096 - proc_macro::bridge::client::Client<proc_macro::TokenStream,proc_macro::TokenStream>::expand1::{{closure}}::{{closure}}::h62de29f5d77914ba
  30:     0x7fffe4e92056 - proc_macro::bridge::client::run_client::{{closure}}::{{closure}}::h0b775401d7e58d66
  31:     0x7fffe4e8fef1 - proc_macro::bridge::client::state::set::h56f286317c15c3e5
  32:     0x7fffe4e91ece - proc_macro::bridge::client::run_client::{{closure}}::hc67799c14faf7179
  33:     0x7fffe4e8ff70 - <core::panic::unwind_safe::AssertUnwindSafe<F> as core::ops::function::FnOnce<()>>::call_once::h89fff44e590d4a34
  34:     0x7fffe4e907dc - std::panicking::catch_unwind::do_call::hb1f61b44bd1bf271
  35:     0x7fffe4e920cb - __rust_try
  36:     0x7fffe4e91ae3 - proc_macro::bridge::client::run_client::h96eece2666342429
  37:     0x7fffe4e9207e - proc_macro::bridge::client::Client<proc_macro::TokenStream,proc_macro::TokenStream>::expand1::{{closure}}::h72f2d63c28d83229
  38:     0x7fffe4e91422 - proc_macro::bridge::selfless_reify::reify_to_extern_c_fn_hrt_bridge::wrapper::h176c9c99eda7eec8
  39:     0x7ffff5ef6181 - <rustc_proc_macro[4c932ddccfb31674]::bridge::server::MaybeCrossThread<rustc_expand[5a74fa380dd05054]::proc_macro::MessagePipe<rustc_proc_macro[4c932ddccfb31674]::bridge::buffer::Buffer>> as rustc_proc_macro[4c932ddccfb31674]::bridge::server::ExecutionStrategy>::run_bridge_and_client::<rustc_proc_macro[4c932ddccfb31674]::bridge::server::Dispatcher<rustc_proc_macro[4c932ddccfb31674]::bridge::server::MarkedTypes<rustc_expand[5a74fa380dd05054]::proc_macro_server::Rustc>>>
  40:     0x7ffff5ef5e92 - <rustc_proc_macro[4c932ddccfb31674]::bridge::client::Client<rustc_proc_macro[4c932ddccfb31674]::TokenStream, rustc_proc_macro[4c932ddccfb31674]::TokenStream>>::run::<rustc_expand[5a74fa380dd05054]::proc_macro_server::Rustc, rustc_proc_macro[4c932ddccfb31674]::bridge::server::MaybeCrossThread<rustc_expand[5a74fa380dd05054]::proc_macro::MessagePipe<rustc_proc_macro[4c932ddccfb31674]::bridge::buffer::Buffer>>>
  41:     0x7ffff5ef35b7 - <rustc_expand[5a74fa380dd05054]::proc_macro::BangProcMacro as rustc_expand[5a74fa380dd05054]::base::BangProcMacro>::expand
  42:     0x7ffff686ea93 - <rustc_expand[5a74fa380dd05054]::expand::MacroExpander>::fully_expand_fragment
  43:     0x7ffff683bb85 - <rustc_expand[5a74fa380dd05054]::expand::MacroExpander>::expand_crate
  44:     0x7ffff5d354ab - rustc_interface[76e547b88cad6d34]::passes::configure_and_expand
  45:     0x7ffff655272d - rustc_interface[76e547b88cad6d34]::passes::resolver_for_lowering_raw
  46:     0x7ffff655248d - rustc_query_impl[2d429222c3b2e6bb]::plumbing::__rust_begin_short_backtrace::<rustc_query_impl[2d429222c3b2e6bb]::query_impl::resolver_for_lowering_raw::dynamic_query::{closure#2}::{closure#0}, rustc_middle[33e32ff2bdd40d7a]::query::erase::Erased<[u8; 16usize]>>
  47:     0x7ffff6552467 - <rustc_query_impl[2d429222c3b2e6bb]::query_impl::resolver_for_lowering_raw::dynamic_query::{closure#2} as core[3960b0be9a8ab2fb]::ops::function::FnOnce<(rustc_middle[33e32ff2bdd40d7a]::ty::context::TyCtxt, ())>>::call_once
  48:     0x7ffff6728d5d - rustc_query_system[cd1a210e7e3190c4]::query::plumbing::try_execute_query::<rustc_query_impl[2d429222c3b2e6bb]::DynamicConfig<rustc_query_system[cd1a210e7e3190c4]::query::caches::SingleCache<rustc_middle[33e32ff2bdd40d7a]::query::erase::Erased<[u8; 16usize]>>, false, false, false>, rustc_query_impl[2d429222c3b2e6bb]::plumbing::QueryCtxt, true>
  49:     0x7ffff672874f - rustc_query_impl[2d429222c3b2e6bb]::query_impl::resolver_for_lowering_raw::get_query_incr::__rust_end_short_backtrace
  50:     0x7ffff64eea8e - rustc_interface[76e547b88cad6d34]::passes::create_and_enter_global_ctxt::<core[3960b0be9a8ab2fb]::option::Option<rustc_interface[76e547b88cad6d34]::queries::Linker>, rustc_driver_impl[8c00ca3c7ff43d1e]::run_compiler::{closure#0}::{closure#2}>::{closure#2}::{closure#0}
  51:     0x7ffff64df83e - rustc_interface[76e547b88cad6d34]::interface::run_compiler::<(), rustc_driver_impl[8c00ca3c7ff43d1e]::run_compiler::{closure#0}>::{closure#1}
  52:     0x7ffff63ea938 - std[868c2b82e02752c5]::sys::backtrace::__rust_begin_short_backtrace::<rustc_interface[76e547b88cad6d34]::util::run_in_thread_with_globals<rustc_interface[76e547b88cad6d34]::util::run_in_thread_pool_with_globals<rustc_interface[76e547b88cad6d34]::interface::run_compiler<(), rustc_driver_impl[8c00ca3c7ff43d1e]::run_compiler::{closure#0}>::{closure#1}, ()>::{closure#0}, ()>::{closure#0}::{closure#0}, ()>
  53:     0x7ffff63ea61c - <<std[868c2b82e02752c5]::thread::Builder>::spawn_unchecked_<rustc_interface[76e547b88cad6d34]::util::run_in_thread_with_globals<rustc_interface[76e547b88cad6d34]::util::run_in_thread_pool_with_globals<rustc_interface[76e547b88cad6d34]::interface::run_compiler<(), rustc_driver_impl[8c00ca3c7ff43d1e]::run_compiler::{closure#0}>::{closure#1}, ()>::{closure#0}, ()>::{closure#0}::{closure#0}, ()>::{closure#1} as core[3960b0be9a8ab2fb]::ops::function::FnOnce<()>>::call_once::{shim:vtable#0}
  54:     0x7ffff63f0c6f - std::sys::thread::unix::Thread::new::thread_start::h10345b7e8309cb92
  55:     0x7fffefa9a97a - start_thread
  56:     0x7fffefb22d2c - __GI___clone3
  57:                0x0 - <unknown>

error: 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 1.91.1 (ed61e7d7e 2025-11-07) running on x86_64-unknown-linux-gnu

note: compiler flags: --crate-type bin -C embed-bitcode=no -C debuginfo=2 -C incremental=[REDACTED]

note: some of the compiler flags provided by cargo are hidden

query stack during panic:
#0 [resolver_for_lowering_raw] getting the resolver for lowering
end of query stack
error: proc macro panicked
 --> minimal_ice/src/main.rs:8:5
  |
8 |     trigger_ice!();
  |     ^^^^^^^^^^^^^^
  |
  = help: message: use-after-free in `proc_macro` handle

error: could not compile `minimal_ice` (bin "minimal_ice") due to 2 previous errors

Beta

rustc 1.92.0-beta.3 (f3f12444a 2025-11-09)
binary: rustc
commit-hash: f3f12444a017add0468f683f3a10656d29438a05
commit-date: 2025-11-09
host: x86_64-unknown-linux-gnu
release: 1.92.0-beta.3
LLVM version: 21.1.3

Beta Backtrace

   Compiling minimal_ice v0.1.0 (/home/muki/Git/mookums/minimal_ice/minimal_ice)
error: Fallible Error
 --> minimal_ice/src/main.rs:4:5
  |
4 |     trigger_ice!();
  |     ^^^^^^^^^^^^^^
  |
  = note: this error originates in the macro `trigger_ice` (in Nightly builds, run with -Z macro-backtrace for more info)


thread 'rustc' (96998) panicked at /rustc-dev/f3f12444a017add0468f683f3a10656d29438a05/compiler/rustc_proc_macro/../../library/proc_macro/src/bridge/handle.rs:73:19:
use-after-free in `proc_macro` handle
stack backtrace:
   0:     0x7ffff4a31ac3 - <std::sys::backtrace::BacktraceLock::print::DisplayBacktrace as core::fmt::Display>::fmt::h3e9d275186baf5f9
   1:     0x7ffff5201b98 - core::fmt::write::hb85a90fbe7ba8ad7
   2:     0x7ffff680c011 - std::io::Write::write_fmt::h0dc6e7a219cbd6b7
   3:     0x7ffff49f7652 - std::sys::backtrace::BacktraceLock::print::h58bb164ecb3a7608
   4:     0x7ffff49fd719 - std::panicking::default_hook::{{closure}}::h112e060ce9c7ec0a
   5:     0x7ffff49fd243 - std::panicking::default_hook::h42eb8101af7ca07b
   6:     0x7ffff39f6861 - std[af028110d1055b0b]::panicking::update_hook::<alloc[6be5232bc8381716]::boxed::Box<rustc_driver_impl[8e26362778fa249e]::install_ice_hook::{closure#1}>>::{closure#0}
   7:     0x7ffff49fdb3f - std::panicking::panic_with_hook::h48e503d1a9999970
   8:     0x7ffff49fd8fa - std::panicking::panic_handler::{{closure}}::h44c20e210d370486
   9:     0x7ffff49f7789 - std::sys::backtrace::__rust_end_short_backtrace::h4d56a29a3f91ad26
  10:     0x7ffff49d818d - __rustc[1720d281c0a319d2]::rust_begin_unwind
  11:     0x7ffff197ed20 - core::panicking::panic_fmt::hbb756acb2f7b23ce
  12:     0x7ffff255632b - core::option::expect_failed::h4297324ea965e01b
  13:     0x7ffff3a9a7ac - <rustc_proc_macro[9b0c2294e94e5d37]::bridge::TokenTree<rustc_proc_macro[9b0c2294e94e5d37]::bridge::Marked<rustc_ast[91f889ff5de43160]::tokenstream::TokenStream, rustc_proc_macro[9b0c2294e94e5d37]::bridge::client::TokenStream>, rustc_proc_macro[9b0c2294e94e5d37]::bridge::Marked<rustc_span[71e329ce9c103f2d]::span_encoding::Span, rustc_proc_macro[9b0c2294e94e5d37]::bridge::client::Span>, rustc_proc_macro[9b0c2294e94e5d37]::bridge::Marked<rustc_span[71e329ce9c103f2d]::symbol::Symbol, rustc_proc_macro[9b0c2294e94e5d37]::bridge::symbol::Symbol>> as rustc_proc_macro[9b0c2294e94e5d37]::bridge::rpc::Decode<rustc_proc_macro[9b0c2294e94e5d37]::bridge::server::HandleStore<rustc_proc_macro[9b0c2294e94e5d37]::bridge::server::MarkedTypes<rustc_expand[9599ee0a5d6b1eb9]::proc_macro_server::Rustc>>>>::decode
  14:     0x7ffff60f1390 - <rustc_proc_macro[9b0c2294e94e5d37]::bridge::server::Dispatcher<rustc_proc_macro[9b0c2294e94e5d37]::bridge::server::MarkedTypes<rustc_expand[9599ee0a5d6b1eb9]::proc_macro_server::Rustc>> as rustc_proc_macro[9b0c2294e94e5d37]::bridge::server::DispatcherTrait>::dispatch
  15:     0x7ffff60ee5b0 - <rustc_proc_macro[9b0c2294e94e5d37]::bridge::closure::Closure<_, _> as core[ed376e679610330f]::convert::From<&mut _>>::from::call::<rustc_proc_macro[9b0c2294e94e5d37]::bridge::buffer::Buffer, rustc_proc_macro[9b0c2294e94e5d37]::bridge::buffer::Buffer, <rustc_proc_macro[9b0c2294e94e5d37]::bridge::server::SameThread as rustc_proc_macro[9b0c2294e94e5d37]::bridge::server::ExecutionStrategy>::run_bridge_and_client<rustc_proc_macro[9b0c2294e94e5d37]::bridge::server::Dispatcher<rustc_proc_macro[9b0c2294e94e5d37]::bridge::server::MarkedTypes<rustc_expand[9599ee0a5d6b1eb9]::proc_macro_server::Rustc>>>::{closure#0}>
  16:     0x7fffe4f3f2a7 - proc_macro::bridge::closure::Closure<A,R>::call::h27e762b8182bc4a7
                               at /rustc/f3f12444a017add0468f683f3a10656d29438a05/library/proc_macro/src/bridge/closure.rs:28:18
  17:     0x7fffe4f3f2a7 - proc_macro::bridge::client::TokenStream::from_token_tree::{{closure}}::h162f1e7289fbdc15
                               at /rustc/f3f12444a017add0468f683f3a10656d29438a05/library/proc_macro/src/bridge/client.rs:144:43
  18:     0x7fffe4f3f2a7 - proc_macro::bridge::client::Bridge::with::{{closure}}::h03d23392bf82d796
                               at /rustc/f3f12444a017add0468f683f3a10656d29438a05/library/proc_macro/src/bridge/client.rs:222:13
  19:     0x7fffe4f3f2a7 - proc_macro::bridge::client::state::with::hf7f615a92f4d4478
                               at /rustc/f3f12444a017add0468f683f3a10656d29438a05/library/proc_macro/src/bridge/client.rs:211:9
  20:     0x7fffe4f3f2a7 - proc_macro::bridge::client::Bridge::with::h6972aaccd4725b8f
                               at /rustc/f3f12444a017add0468f683f3a10656d29438a05/library/proc_macro/src/bridge/client.rs:217:9
  21:     0x7fffe4f3f2a7 - proc_macro::bridge::client::TokenStream::from_token_tree::h1ce468960c9ab270
                               at /rustc/f3f12444a017add0468f683f3a10656d29438a05/library/proc_macro/src/bridge/client.rs:137:17
  22:     0x7fffe4f3f2a7 - <proc_macro::TokenStream as core::convert::From<proc_macro::TokenTree>>::from::he7e00bfd6782b227
                               at /rustc/f3f12444a017add0468f683f3a10656d29438a05/library/proc_macro/src/lib.rs:257:26
  23:     0x7fffe4f32c40 - <proc_macro2::imp::TokenStream as core::convert::From<proc_macro2::TokenTree>>::from::h2f13d9f4712113cb
  24:     0x7fffe4f32af9 - <proc_macro2::TokenStream as core::convert::From<proc_macro2::TokenTree>>::from::h90d692e625f9f18b
  25:     0x7fffe4f2c57b - syn::error::ErrorMessage::to_compile_error::h8eb307be4eef352d
  26:     0x7fffe4f2c73a - syn::error::Error::to_compile_error::h1c2ace24c1884cc4
  27:     0x7fffe4f28912 - minimal_ice_macro::trigger_ice::hb4f9fc17fc3832e0
  28:     0x7fffe4f2b36e - core::ops::function::Fn::call::h76f1ee09387cb84c
  29:     0x7fffe4f2a986 - proc_macro::bridge::client::Client<proc_macro::TokenStream,proc_macro::TokenStream>::expand1::{{closure}}::{{closure}}::h7314bc6bbf5b3c06
  30:     0x7fffe4f2a946 - proc_macro::bridge::client::run_client::{{closure}}::{{closure}}::h903e16cb6e84f8a0
  31:     0x7fffe4f2a251 - proc_macro::bridge::client::state::set::h6414b07d76a35005
  32:     0x7fffe4f2a7be - proc_macro::bridge::client::run_client::{{closure}}::h1d14b2bc08673617
  33:     0x7fffe4f28790 - <core::panic::unwind_safe::AssertUnwindSafe<F> as core::ops::function::FnOnce<()>>::call_once::h65989b2034e597d5
  34:     0x7fffe4f2a9fc - std::panicking::catch_unwind::do_call::h7517074ff958203a
  35:     0x7fffe4f2a9bb - __rust_try
  36:     0x7fffe4f2a3d3 - proc_macro::bridge::client::run_client::hcaeeb7caea47ff5e
  37:     0x7fffe4f2a96e - proc_macro::bridge::client::Client<proc_macro::TokenStream,proc_macro::TokenStream>::expand1::{{closure}}::hc7580236c8388686
  38:     0x7fffe4f29742 - proc_macro::bridge::selfless_reify::reify_to_extern_c_fn_hrt_bridge::wrapper::h24ff7b36245e8635
  39:     0x7ffff5f00681 - <rustc_proc_macro[9b0c2294e94e5d37]::bridge::server::MaybeCrossThread<rustc_expand[9599ee0a5d6b1eb9]::proc_macro::MessagePipe<rustc_proc_macro[9b0c2294e94e5d37]::bridge::buffer::Buffer>> as rustc_proc_macro[9b0c2294e94e5d37]::bridge::server::ExecutionStrategy>::run_bridge_and_client::<rustc_proc_macro[9b0c2294e94e5d37]::bridge::server::Dispatcher<rustc_proc_macro[9b0c2294e94e5d37]::bridge::server::MarkedTypes<rustc_expand[9599ee0a5d6b1eb9]::proc_macro_server::Rustc>>>
  40:     0x7ffff5f00392 - <rustc_proc_macro[9b0c2294e94e5d37]::bridge::client::Client<rustc_proc_macro[9b0c2294e94e5d37]::TokenStream, rustc_proc_macro[9b0c2294e94e5d37]::TokenStream>>::run::<rustc_expand[9599ee0a5d6b1eb9]::proc_macro_server::Rustc, rustc_proc_macro[9b0c2294e94e5d37]::bridge::server::MaybeCrossThread<rustc_expand[9599ee0a5d6b1eb9]::proc_macro::MessagePipe<rustc_proc_macro[9b0c2294e94e5d37]::bridge::buffer::Buffer>>>
  41:     0x7ffff5efe177 - <rustc_expand[9599ee0a5d6b1eb9]::proc_macro::BangProcMacro as rustc_expand[9599ee0a5d6b1eb9]::base::BangProcMacro>::expand
  42:     0x7ffff67bc4cc - <rustc_expand[9599ee0a5d6b1eb9]::expand::MacroExpander>::fully_expand_fragment
  43:     0x7ffff67847a9 - <rustc_expand[9599ee0a5d6b1eb9]::expand::MacroExpander>::expand_crate
  44:     0x7ffff5ce4924 - rustc_interface[7594eb8868074b87]::passes::configure_and_expand
  45:     0x7ffff6372b95 - rustc_interface[7594eb8868074b87]::passes::resolver_for_lowering_raw
  46:     0x7ffff637290d - rustc_query_impl[d188527145c04d80]::plumbing::__rust_begin_short_backtrace::<rustc_query_impl[d188527145c04d80]::query_impl::resolver_for_lowering_raw::dynamic_query::{closure#2}::{closure#0}, rustc_middle[bd6923619f42b0b9]::query::erase::Erased<[u8; 16usize]>>
  47:     0x7ffff63728e9 - <rustc_query_impl[d188527145c04d80]::query_impl::resolver_for_lowering_raw::dynamic_query::{closure#2} as core[ed376e679610330f]::ops::function::FnOnce<(rustc_middle[bd6923619f42b0b9]::ty::context::TyCtxt, ())>>::call_once
  48:     0x7ffff64f5e7d - rustc_query_system[d8a6e816219f7c4b]::query::plumbing::try_execute_query::<rustc_query_impl[d188527145c04d80]::DynamicConfig<rustc_query_system[d8a6e816219f7c4b]::query::caches::SingleCache<rustc_middle[bd6923619f42b0b9]::query::erase::Erased<[u8; 16usize]>>, false, false, false>, rustc_query_impl[d188527145c04d80]::plumbing::QueryCtxt, true>
  49:     0x7ffff64f5851 - rustc_query_impl[d188527145c04d80]::query_impl::resolver_for_lowering_raw::get_query_incr::__rust_end_short_backtrace
  50:     0x7ffff64e872a - <rustc_interface[7594eb8868074b87]::passes::create_and_enter_global_ctxt<core[ed376e679610330f]::option::Option<rustc_interface[7594eb8868074b87]::queries::Linker>, rustc_driver_impl[8e26362778fa249e]::run_compiler::{closure#0}::{closure#2}>::{closure#2} as core[ed376e679610330f]::ops::function::FnOnce<(&rustc_session[a16f20ed1a24abe7]::session::Session, rustc_middle[bd6923619f42b0b9]::ty::context::CurrentGcx, alloc[6be5232bc8381716]::sync::Arc<rustc_data_structures[62f0d6f7c43ee74a]::jobserver::Proxy>, &std[af028110d1055b0b]::sync::once_lock::OnceLock<rustc_middle[bd6923619f42b0b9]::ty::context::GlobalCtxt>, &rustc_data_structures[62f0d6f7c43ee74a]::sync::worker_local::WorkerLocal<rustc_middle[bd6923619f42b0b9]::arena::Arena>, &rustc_data_structures[62f0d6f7c43ee74a]::sync::worker_local::WorkerLocal<rustc_hir[af2b1261e8482175]::Arena>, rustc_driver_impl[8e26362778fa249e]::run_compiler::{closure#0}::{closure#2})>>::call_once::{shim:vtable#0}
  51:     0x7ffff63dad22 - rustc_interface[7594eb8868074b87]::interface::run_compiler::<(), rustc_driver_impl[8e26362778fa249e]::run_compiler::{closure#0}>::{closure#1}
  52:     0x7ffff5f84a78 - std[af028110d1055b0b]::sys::backtrace::__rust_begin_short_backtrace::<rustc_interface[7594eb8868074b87]::util::run_in_thread_with_globals<rustc_interface[7594eb8868074b87]::util::run_in_thread_pool_with_globals<rustc_interface[7594eb8868074b87]::interface::run_compiler<(), rustc_driver_impl[8e26362778fa249e]::run_compiler::{closure#0}>::{closure#1}, ()>::{closure#0}, ()>::{closure#0}::{closure#0}, ()>
  53:     0x7ffff5f84748 - <<std[af028110d1055b0b]::thread::Builder>::spawn_unchecked_<rustc_interface[7594eb8868074b87]::util::run_in_thread_with_globals<rustc_interface[7594eb8868074b87]::util::run_in_thread_pool_with_globals<rustc_interface[7594eb8868074b87]::interface::run_compiler<(), rustc_driver_impl[8e26362778fa249e]::run_compiler::{closure#0}>::{closure#1}, ()>::{closure#0}, ()>::{closure#0}::{closure#0}, ()>::{closure#1} as core[ed376e679610330f]::ops::function::FnOnce<()>>::call_once::{shim:vtable#0}
  54:     0x7ffff5f830af - std::sys::thread::unix::Thread::new::thread_start::h08ac2fb5a17180df
  55:     0x7fffefa9a97a - start_thread
  56:     0x7fffefb22d2c - __GI___clone3
  57:                0x0 - <unknown>

error: 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 1.92.0-beta.3 (f3f12444a 2025-11-09) running on x86_64-unknown-linux-gnu

note: compiler flags: --crate-type bin -C embed-bitcode=no -C debuginfo=2 -C incremental=[REDACTED]

note: some of the compiler flags provided by cargo are hidden

query stack during panic:
#0 [resolver_for_lowering_raw] getting the resolver for lowering
end of query stack
error: proc macro panicked
 --> minimal_ice/src/main.rs:8:5
  |
8 |     trigger_ice!();
  |     ^^^^^^^^^^^^^^
  |
  = help: message: use-after-free in `proc_macro` handle

error: could not compile `minimal_ice` (bin "minimal_ice") due to 2 previous errors

Nightly

rustc 1.93.0-nightly (cc3eee7fb 2025-11-28)
binary: rustc
commit-hash: cc3eee7fbe17ea4b7238531cb97e1b7b8bd6afce
commit-date: 2025-11-28
host: x86_64-unknown-linux-gnu
release: 1.93.0-nightly
LLVM version: 21.1.5

Nightly Backtrace

   Compiling minimal_ice v0.1.0 (/home/muki/Git/mookums/minimal_ice/minimal_ice)
error: Fallible Error
 --> minimal_ice/src/main.rs:4:5
  |
4 |     trigger_ice!();
  |     ^^^^^^^^^^^^^^
  |
  = note: this error originates in the macro `trigger_ice` (in Nightly builds, run with -Z macro-backtrace for more info)


thread 'rustc' (142190) panicked at /rustc-dev/cc3eee7fbe17ea4b7238531cb97e1b7b8bd6afce/compiler/rustc_proc_macro/../../library/proc_macro/src/bridge/handle.rs:73:19:
use-after-free in `proc_macro` handle
stack backtrace:
   0:     0x7ffff4c5e473 - <<std[cbf56a46dac989f5]::sys::backtrace::BacktraceLock>::print::DisplayBacktrace as core[a3424aac13c77cf6]::fmt::Display>::fmt
   1:     0x7ffff5211d88 - core[a3424aac13c77cf6]::fmt::write
   2:     0x7ffff4c74de6 - <std[cbf56a46dac989f5]::sys::stdio::unix::Stderr as std[cbf56a46dac989f5]::io::Write>::write_fmt
   3:     0x7ffff4c34def - std[cbf56a46dac989f5]::panicking::default_hook::{closure#0}
   4:     0x7ffff4c545a0 - std[cbf56a46dac989f5]::panicking::default_hook
   5:     0x7ffff3cbf737 - std[cbf56a46dac989f5]::panicking::update_hook::<alloc[9fa3fef380221c31]::boxed::Box<rustc_driver_impl[9601b55f30d2923c]::install_ice_hook::{closure#1}>>::{closure#0}
   6:     0x7ffff4c54882 - std[cbf56a46dac989f5]::panicking::panic_with_hook
   7:     0x7ffff4c34f48 - std[cbf56a46dac989f5]::panicking::panic_handler::{closure#0}
   8:     0x7ffff4c2bfc9 - std[cbf56a46dac989f5]::sys::backtrace::__rust_end_short_backtrace::<std[cbf56a46dac989f5]::panicking::panic_handler::{closure#0}, !>
   9:     0x7ffff4c36a9d - __rustc[f3f8441e4970532f]::rust_begin_unwind
  10:     0x7ffff1f9526c - core[a3424aac13c77cf6]::panicking::panic_fmt
  11:     0x7ffff260c7c4 - core[a3424aac13c77cf6]::option::expect_failed
  12:     0x7ffff3d7e7ec - <rustc_proc_macro[396dcc20919f0e14]::bridge::TokenTree<rustc_proc_macro[396dcc20919f0e14]::bridge::Marked<rustc_ast[ef2e9f90390c76f5]::tokenstream::TokenStream, rustc_proc_macro[396dcc20919f0e14]::bridge::client::TokenStream>, rustc_proc_macro[396dcc20919f0e14]::bridge::Marked<rustc_span[577032adbb3e2bdb]::span_encoding::Span, rustc_proc_macro[396dcc20919f0e14]::bridge::client::Span>, rustc_proc_macro[396dcc20919f0e14]::bridge::Marked<rustc_span[577032adbb3e2bdb]::symbol::Symbol, rustc_proc_macro[396dcc20919f0e14]::bridge::symbol::Symbol>> as rustc_proc_macro[396dcc20919f0e14]::bridge::rpc::Decode<rustc_proc_macro[396dcc20919f0e14]::bridge::server::HandleStore<rustc_proc_macro[396dcc20919f0e14]::bridge::server::MarkedTypes<rustc_expand[b07ac48910fdba03]::proc_macro_server::Rustc>>>>::decode
  13:     0x7ffff610ad90 - <rustc_proc_macro[396dcc20919f0e14]::bridge::server::Dispatcher<rustc_proc_macro[396dcc20919f0e14]::bridge::server::MarkedTypes<rustc_expand[b07ac48910fdba03]::proc_macro_server::Rustc>> as rustc_proc_macro[396dcc20919f0e14]::bridge::server::DispatcherTrait>::dispatch
  14:     0x7ffff6107fb0 - <rustc_proc_macro[396dcc20919f0e14]::bridge::closure::Closure<_, _> as core[a3424aac13c77cf6]::convert::From<&mut _>>::from::call::<rustc_proc_macro[396dcc20919f0e14]::bridge::buffer::Buffer, rustc_proc_macro[396dcc20919f0e14]::bridge::buffer::Buffer, <rustc_proc_macro[396dcc20919f0e14]::bridge::server::SameThread as rustc_proc_macro[396dcc20919f0e14]::bridge::server::ExecutionStrategy>::run_bridge_and_client<rustc_proc_macro[396dcc20919f0e14]::bridge::server::Dispatcher<rustc_proc_macro[396dcc20919f0e14]::bridge::server::MarkedTypes<rustc_expand[b07ac48910fdba03]::proc_macro_server::Rustc>>>::{closure#0}>
  15:     0x7fffe531dd67 - <proc_macro[f63ca3dfe5772356]::bridge::closure::Closure<proc_macro[f63ca3dfe5772356]::bridge::buffer::Buffer, proc_macro[f63ca3dfe5772356]::bridge::buffer::Buffer>>::call
                               at /rustc/cc3eee7fbe17ea4b7238531cb97e1b7b8bd6afce/library/proc_macro/src/bridge/closure.rs:28:18
  16:     0x7fffe531dd67 - <proc_macro[f63ca3dfe5772356]::bridge::client::TokenStream>::from_token_tree::{closure#0}
                               at /rustc/cc3eee7fbe17ea4b7238531cb97e1b7b8bd6afce/library/proc_macro/src/bridge/client.rs:144:43
  17:     0x7fffe531dd67 - <proc_macro[f63ca3dfe5772356]::bridge::client::Bridge>::with::<proc_macro[f63ca3dfe5772356]::bridge::client::TokenStream, <proc_macro[f63ca3dfe5772356]::bridge::client::TokenStream>::from_token_tree::{closure#0}>::{closure#0}
                               at /rustc/cc3eee7fbe17ea4b7238531cb97e1b7b8bd6afce/library/proc_macro/src/bridge/client.rs:222:13
  18:     0x7fffe531dd67 - proc_macro[f63ca3dfe5772356]::bridge::client::state::with::<proc_macro[f63ca3dfe5772356]::bridge::client::TokenStream, <proc_macro[f63ca3dfe5772356]::bridge::client::Bridge>::with<proc_macro[f63ca3dfe5772356]::bridge::client::TokenStream, <proc_macro[f63ca3dfe5772356]::bridge::client::TokenStream>::from_token_tree::{closure#0}>::{closure#0}>
                               at /rustc/cc3eee7fbe17ea4b7238531cb97e1b7b8bd6afce/library/proc_macro/src/bridge/client.rs:211:9
  19:     0x7fffe531dd67 - <proc_macro[f63ca3dfe5772356]::bridge::client::Bridge>::with::<proc_macro[f63ca3dfe5772356]::bridge::client::TokenStream, <proc_macro[f63ca3dfe5772356]::bridge::client::TokenStream>::from_token_tree::{closure#0}>
                               at /rustc/cc3eee7fbe17ea4b7238531cb97e1b7b8bd6afce/library/proc_macro/src/bridge/client.rs:217:9
  20:     0x7fffe531dd67 - <proc_macro[f63ca3dfe5772356]::bridge::client::TokenStream>::from_token_tree
                               at /rustc/cc3eee7fbe17ea4b7238531cb97e1b7b8bd6afce/library/proc_macro/src/bridge/client.rs:137:17
  21:     0x7fffe531dd67 - <proc_macro[f63ca3dfe5772356]::TokenStream as core[a3424aac13c77cf6]::convert::From<proc_macro[f63ca3dfe5772356]::TokenTree>>::from
                               at /rustc/cc3eee7fbe17ea4b7238531cb97e1b7b8bd6afce/library/proc_macro/src/lib.rs:257:26
  22:     0x7fffe5310690 - <proc_macro2[f2e3d13f49dc920e]::imp::TokenStream as core[a3424aac13c77cf6]::convert::From<proc_macro2[f2e3d13f49dc920e]::TokenTree>>::from
  23:     0x7fffe5314021 - <proc_macro2[f2e3d13f49dc920e]::TokenStream as core[a3424aac13c77cf6]::convert::From<proc_macro2[f2e3d13f49dc920e]::TokenTree>>::from
  24:     0x7fffe530aa2b - <syn[83b5691fa31d6ac]::error::ErrorMessage>::to_compile_error
  25:     0x7fffe530a60a - <syn[83b5691fa31d6ac]::error::Error>::to_compile_error
  26:     0x7fffe5307cf2 - minimal_ice_macro[4567a4db178e6784]::trigger_ice
  27:     0x7fffe53091ee - <minimal_ice_macro[4567a4db178e6784]::trigger_ice as core[a3424aac13c77cf6]::ops::function::Fn<(proc_macro[f63ca3dfe5772356]::TokenStream,)>>::call
  28:     0x7fffe53089f6 - <proc_macro[f63ca3dfe5772356]::bridge::client::Client<proc_macro[f63ca3dfe5772356]::TokenStream, proc_macro[f63ca3dfe5772356]::TokenStream>>::expand1::<minimal_ice_macro[4567a4db178e6784]::trigger_ice>::{closure#0}::{closure#0}
  29:     0x7fffe5308a06 - proc_macro[f63ca3dfe5772356]::bridge::client::run_client::<proc_macro[f63ca3dfe5772356]::bridge::client::TokenStream, core[a3424aac13c77cf6]::option::Option<proc_macro[f63ca3dfe5772356]::bridge::client::TokenStream>, <proc_macro[f63ca3dfe5772356]::bridge::client::Client<proc_macro[f63ca3dfe5772356]::TokenStream, proc_macro[f63ca3dfe5772356]::TokenStream>>::expand1<minimal_ice_macro[4567a4db178e6784]::trigger_ice>::{closure#0}::{closure#0}>::{closure#0}::{closure#0}
  30:     0x7fffe5308161 - proc_macro[f63ca3dfe5772356]::bridge::client::state::set::<core[a3424aac13c77cf6]::option::Option<proc_macro[f63ca3dfe5772356]::bridge::client::TokenStream>, proc_macro[f63ca3dfe5772356]::bridge::client::run_client<proc_macro[f63ca3dfe5772356]::bridge::client::TokenStream, core[a3424aac13c77cf6]::option::Option<proc_macro[f63ca3dfe5772356]::bridge::client::TokenStream>, <proc_macro[f63ca3dfe5772356]::bridge::client::Client<proc_macro[f63ca3dfe5772356]::TokenStream, proc_macro[f63ca3dfe5772356]::TokenStream>>::expand1<minimal_ice_macro[4567a4db178e6784]::trigger_ice>::{closure#0}::{closure#0}>::{closure#0}::{closure#0}>
  31:     0x7fffe530886e - proc_macro[f63ca3dfe5772356]::bridge::client::run_client::<proc_macro[f63ca3dfe5772356]::bridge::client::TokenStream, core[a3424aac13c77cf6]::option::Option<proc_macro[f63ca3dfe5772356]::bridge::client::TokenStream>, <proc_macro[f63ca3dfe5772356]::bridge::client::Client<proc_macro[f63ca3dfe5772356]::TokenStream, proc_macro[f63ca3dfe5772356]::TokenStream>>::expand1<minimal_ice_macro[4567a4db178e6784]::trigger_ice>::{closure#0}::{closure#0}>::{closure#0}
  32:     0x7fffe53094e0 - <core[a3424aac13c77cf6]::panic::unwind_safe::AssertUnwindSafe<proc_macro[f63ca3dfe5772356]::bridge::client::run_client<proc_macro[f63ca3dfe5772356]::bridge::client::TokenStream, core[a3424aac13c77cf6]::option::Option<proc_macro[f63ca3dfe5772356]::bridge::client::TokenStream>, <proc_macro[f63ca3dfe5772356]::bridge::client::Client<proc_macro[f63ca3dfe5772356]::TokenStream, proc_macro[f63ca3dfe5772356]::TokenStream>>::expand1<minimal_ice_macro[4567a4db178e6784]::trigger_ice>::{closure#0}::{closure#0}>::{closure#0}> as core[a3424aac13c77cf6]::ops::function::FnOnce<()>>::call_once
  33:     0x7fffe530830c - std[cbf56a46dac989f5]::panicking::catch_unwind::do_call::<core[a3424aac13c77cf6]::panic::unwind_safe::AssertUnwindSafe<proc_macro[f63ca3dfe5772356]::bridge::client::run_client<proc_macro[f63ca3dfe5772356]::bridge::client::TokenStream, core[a3424aac13c77cf6]::option::Option<proc_macro[f63ca3dfe5772356]::bridge::client::TokenStream>, <proc_macro[f63ca3dfe5772356]::bridge::client::Client<proc_macro[f63ca3dfe5772356]::TokenStream, proc_macro[f63ca3dfe5772356]::TokenStream>>::expand1<minimal_ice_macro[4567a4db178e6784]::trigger_ice>::{closure#0}::{closure#0}>::{closure#0}>, ()>
  34:     0x7fffe5308a7b - __rust_try
  35:     0x7fffe5308453 - proc_macro[f63ca3dfe5772356]::bridge::client::run_client::<proc_macro[f63ca3dfe5772356]::bridge::client::TokenStream, core[a3424aac13c77cf6]::option::Option<proc_macro[f63ca3dfe5772356]::bridge::client::TokenStream>, <proc_macro[f63ca3dfe5772356]::bridge::client::Client<proc_macro[f63ca3dfe5772356]::TokenStream, proc_macro[f63ca3dfe5772356]::TokenStream>>::expand1<minimal_ice_macro[4567a4db178e6784]::trigger_ice>::{closure#0}::{closure#0}>
  36:     0x7fffe530860e - <proc_macro[f63ca3dfe5772356]::bridge::client::Client<proc_macro[f63ca3dfe5772356]::TokenStream, proc_macro[f63ca3dfe5772356]::TokenStream>>::expand1::<minimal_ice_macro[4567a4db178e6784]::trigger_ice>::{closure#0}
  37:     0x7fffe5309802 - proc_macro[f63ca3dfe5772356]::bridge::selfless_reify::reify_to_extern_c_fn_hrt_bridge::wrapper::<proc_macro[f63ca3dfe5772356]::bridge::buffer::Buffer, <proc_macro[f63ca3dfe5772356]::bridge::client::Client<proc_macro[f63ca3dfe5772356]::TokenStream, proc_macro[f63ca3dfe5772356]::TokenStream>>::expand1<minimal_ice_macro[4567a4db178e6784]::trigger_ice>::{closure#0}>
  38:     0x7ffff5edb501 - <rustc_proc_macro[396dcc20919f0e14]::bridge::server::MaybeCrossThread<rustc_expand[b07ac48910fdba03]::proc_macro::MessagePipe<rustc_proc_macro[396dcc20919f0e14]::bridge::buffer::Buffer>> as rustc_proc_macro[396dcc20919f0e14]::bridge::server::ExecutionStrategy>::run_bridge_and_client::<rustc_proc_macro[396dcc20919f0e14]::bridge::server::Dispatcher<rustc_proc_macro[396dcc20919f0e14]::bridge::server::MarkedTypes<rustc_expand[b07ac48910fdba03]::proc_macro_server::Rustc>>>
  39:     0x7ffff5edb224 - <rustc_proc_macro[396dcc20919f0e14]::bridge::client::Client<rustc_proc_macro[396dcc20919f0e14]::TokenStream, rustc_proc_macro[396dcc20919f0e14]::TokenStream>>::run::<rustc_expand[b07ac48910fdba03]::proc_macro_server::Rustc, rustc_proc_macro[396dcc20919f0e14]::bridge::server::MaybeCrossThread<rustc_expand[b07ac48910fdba03]::proc_macro::MessagePipe<rustc_proc_macro[396dcc20919f0e14]::bridge::buffer::Buffer>>>
  40:     0x7ffff5ed9077 - <rustc_expand[b07ac48910fdba03]::proc_macro::BangProcMacro as rustc_expand[b07ac48910fdba03]::base::BangProcMacro>::expand
  41:     0x7ffff66633e1 - <rustc_expand[b07ac48910fdba03]::expand::MacroExpander>::fully_expand_fragment
  42:     0x7ffff662b20e - <rustc_expand[b07ac48910fdba03]::expand::MacroExpander>::expand_crate
  43:     0x7ffff5c8303c - rustc_interface[4796e4db9508b896]::passes::configure_and_expand
  44:     0x7ffff6357f15 - rustc_interface[4796e4db9508b896]::passes::resolver_for_lowering_raw
  45:     0x7ffff6357c8d - rustc_query_impl[48c5202159a19ef7]::plumbing::__rust_begin_short_backtrace::<rustc_query_impl[48c5202159a19ef7]::query_impl::resolver_for_lowering_raw::dynamic_query::{closure#2}::{closure#0}, rustc_middle[e9d0f7e844f3166b]::query::erase::Erased<[u8; 16usize]>>
  46:     0x7ffff6357c67 - <rustc_query_impl[48c5202159a19ef7]::query_impl::resolver_for_lowering_raw::dynamic_query::{closure#2} as core[a3424aac13c77cf6]::ops::function::FnOnce<(rustc_middle[e9d0f7e844f3166b]::ty::context::TyCtxt, ())>>::call_once
  47:     0x7ffff66d3bd1 - rustc_query_system[3f0601432c754995]::query::plumbing::try_execute_query::<rustc_query_impl[48c5202159a19ef7]::DynamicConfig<rustc_query_system[3f0601432c754995]::query::caches::SingleCache<rustc_middle[e9d0f7e844f3166b]::query::erase::Erased<[u8; 16usize]>>, false, false, false>, rustc_query_impl[48c5202159a19ef7]::plumbing::QueryCtxt, true>
  48:     0x7ffff66d35c1 - rustc_query_impl[48c5202159a19ef7]::query_impl::resolver_for_lowering_raw::get_query_incr::__rust_end_short_backtrace
  49:     0x7ffff64bcdfa - <rustc_interface[4796e4db9508b896]::passes::create_and_enter_global_ctxt<core[a3424aac13c77cf6]::option::Option<rustc_interface[4796e4db9508b896]::queries::Linker>, rustc_driver_impl[9601b55f30d2923c]::run_compiler::{closure#0}::{closure#2}>::{closure#2} as core[a3424aac13c77cf6]::ops::function::FnOnce<(&rustc_session[8beb91a8b00f9da9]::session::Session, rustc_middle[e9d0f7e844f3166b]::ty::context::CurrentGcx, alloc[9fa3fef380221c31]::sync::Arc<rustc_data_structures[22be9c18f5b496a9]::jobserver::Proxy>, &std[cbf56a46dac989f5]::sync::once_lock::OnceLock<rustc_middle[e9d0f7e844f3166b]::ty::context::GlobalCtxt>, &rustc_data_structures[22be9c18f5b496a9]::sync::worker_local::WorkerLocal<rustc_middle[e9d0f7e844f3166b]::arena::Arena>, &rustc_data_structures[22be9c18f5b496a9]::sync::worker_local::WorkerLocal<rustc_hir[bb83e21edf5dc5d8]::Arena>, rustc_driver_impl[9601b55f30d2923c]::run_compiler::{closure#0}::{closure#2})>>::call_once::{shim:vtable#0}
  50:     0x7ffff6304e45 - rustc_interface[4796e4db9508b896]::interface::run_compiler::<(), rustc_driver_impl[9601b55f30d2923c]::run_compiler::{closure#0}>::{closure#1}
  51:     0x7ffff62da44a - std[cbf56a46dac989f5]::sys::backtrace::__rust_begin_short_backtrace::<rustc_interface[4796e4db9508b896]::util::run_in_thread_with_globals<rustc_interface[4796e4db9508b896]::util::run_in_thread_pool_with_globals<rustc_interface[4796e4db9508b896]::interface::run_compiler<(), rustc_driver_impl[9601b55f30d2923c]::run_compiler::{closure#0}>::{closure#1}, ()>::{closure#0}, ()>::{closure#0}::{closure#0}, ()>
  52:     0x7ffff62da154 - <<std[cbf56a46dac989f5]::thread::Builder>::spawn_unchecked_<rustc_interface[4796e4db9508b896]::util::run_in_thread_with_globals<rustc_interface[4796e4db9508b896]::util::run_in_thread_pool_with_globals<rustc_interface[4796e4db9508b896]::interface::run_compiler<(), rustc_driver_impl[9601b55f30d2923c]::run_compiler::{closure#0}>::{closure#1}, ()>::{closure#0}, ()>::{closure#0}::{closure#0}, ()>::{closure#1} as core[a3424aac13c77cf6]::ops::function::FnOnce<()>>::call_once::{shim:vtable#0}
  53:     0x7ffff62d7bef - <std[cbf56a46dac989f5]::sys::thread::unix::Thread>::new::thread_start
  54:     0x7fffefe9a97a - start_thread
  55:     0x7fffeff22d2c - __GI___clone3
  56:                0x0 - <unknown>

error: 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: please make sure that you have updated to the latest nightly

note: please attach the file at `/home/muki/Git/mookums/minimal_ice/rustc-ice-2025-11-29T22_14_05-142188.txt` to your bug report

note: compiler flags: --crate-type bin -C embed-bitcode=no -C debuginfo=2 -C incremental=[REDACTED]

note: some of the compiler flags provided by cargo are hidden

query stack during panic:
#0 [resolver_for_lowering_raw] getting the resolver for lowering
end of query stack
error: proc macro panicked
 --> minimal_ice/src/main.rs:8:5
  |
8 |     trigger_ice!();
  |     ^^^^^^^^^^^^^^
  |
  = help: message: use-after-free in `proc_macro` handle

error: could not compile `minimal_ice` (bin "minimal_ice") due to 2 previous errors

[cyrgani]

smaller:

/// proc-macro crate lib.rs
use proc_macro::{Ident, Span, TokenStream, TokenTree};
use std::{iter::once, sync::LazyLock};

struct ThreadBound(Span);
unsafe impl Sync for ThreadBound {}
unsafe impl Send for ThreadBound {}

static SHARED: LazyLock<ThreadBound> = LazyLock::new(|| ThreadBound(Span::call_site()));

#[proc_macro]
pub fn trigger_ice(_input: TokenStream) -> TokenStream {
    let mut tokens = proc_macro::TokenStream::new();

    tokens.extend(once(TokenTree::Ident(Ident::new(
        "compile_error",
        SHARED.0,
    ))));

    tokens
}

or with the safety checks from syn still in place:

/// proc-macro crate lib.rs
use proc_macro::{Ident, Span, TokenStream, TokenTree};
use std::{
    iter::once,
    sync::LazyLock,
    thread::{self, ThreadId},
};

pub(crate) struct ThreadBound<T> {
    value: T,
    thread_id: ThreadId,
}

unsafe impl<T> Sync for ThreadBound<T> {}

// Send bound requires Copy, as otherwise Drop could run in the wrong place.
//
// Today Copy and Drop are mutually exclusive so `T: Copy` implies `T: !Drop`.
// This impl needs to be revisited if that restriction is relaxed in the future.
unsafe impl<T: Copy> Send for ThreadBound<T> {}

static SHARED: LazyLock<ThreadBound<Span>> = LazyLock::new(|| {
    let value = Span::call_site();
    ThreadBound {
        value,
        thread_id: thread::current().id(),
    }
});

#[proc_macro]
pub fn trigger_ice(_input: TokenStream) -> TokenStream {
    assert!(thread::current().id() == SHARED.thread_id);
    let mut tokens = proc_macro::TokenStream::new();

    tokens.extend(once(TokenTree::Ident(Ident::new(
        "compile_error",
        SHARED.value,
    ))));

    tokens
}

similar to #66003

[roussov]

/// proc-macro crate lib.rs
use proc_macro::TokenStream;
use proc_macro2::Span;
use quote::quote;
use std::sync::LazyLock;
use syn::Error;

#[derive(Debug)]
struct FallibleError;

impl std::fmt::Display for FallibleError {
    fn fmt(&self, f: &mut std::fmt::Formatter<'_>) -> std::fmt::Result {
        write!(f, "Fallible Error")
    }
}

fn fallible_function() -> Result<(), FallibleError> {
    Err(FallibleError)
}

static SHARED: LazyLock<Result<(), Error>> = LazyLock::new(|| {
    // On retourne directement le `Result<(), Error>` attendu par LazyLock,
    // sans passer par `?` + `Ok(())`.
    fallible_function().map_err(|e| Error::new(Span::call_site(), e.to_string()))
});

#[proc_macro]
pub fn trigger_ice(_input: TokenStream) -> TokenStream {
    match SHARED.as_ref() {
        Ok(_) => quote! { fn it_worked() {} }.into(),
        Err(e) => e.to_compile_error().into(),
    }
}

/// main.rs
use minimal_ice_macro::trigger_ice;


trigger_ice!();

fn helper1() {
    
    it_worked();
}

fn helper2() {
    it_worked();
}

fn main() {
    helper1();
    helper2();
}

[bjorn3]

It is very much intended that proc-macros panic if you try to reuse a proc-macro handle between proc-macro invocations. The handle interner is cleared between proc-macro invocations and doesn't reuse handle numbers. The only bug here is that an ICE message is shown rather than just the error: proc macro panicked error.