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[ICE]: cannot decode AttrId with CacheDecoder #155139
Description
Code
Not sure what caused it. Only happens on debug mode.
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rustc --version --verbose:
rustc version: 1.96.0-nightly (900485642 2026-04-08)
thread 'rustc' panicked at /rustc-dev/900485642855f4729d926ecf24680a791f9293cf/compiler/rustc_middle/src/query/on_disk_cache.rs:663:9:
cannot decode `AttrId` with `CacheDecoder`
stack backtrace:
0: 0x113521c08 - <std[cc2a4db2680813b8]::backtrace::Backtrace>::create
1: 0x1113aeee0 - std[cc2a4db2680813b8]::panicking::update_hook::<alloc[5c025890d9b65067]::boxed::Box<rustc_driver_impl[a9b8195e93143871]::install_ice_hook::{closure#1}>>::{closure#0}
2: 0x11353369c - std[cc2a4db2680813b8]::panicking::panic_with_hook
3: 0x113517620 - std[cc2a4db2680813b8]::panicking::panic_handler::{closure#0}
4: 0x11350df98 - std[cc2a4db2680813b8]::sys::backtrace::__rust_end_short_backtrace::<std[cc2a4db2680813b8]::panicking::panic_handler::{closure#0}, !>
5: 0x113518bc4 - __rustc[9893dd7cded7045d]::rust_begin_unwind
6: 0x116554044 - core[65d2295b482aced]::panicking::panic_fmt
7: 0x11212ed30 - <rustc_middle[4fc8633060c41573]::query::on_disk_cache::OnDiskCache>::load_side_effect
8: 0x112ca46d8 - <rustc_query_impl[95864d7e07eebc26]::dep_kind_vtables::non_query::SideEffect::{closure#0} as core[65d2295b482aced]::ops::function::FnOnce<(rustc_middle[4fc8633060c41573]::ty::context::TyCtxt, rustc_middle[4fc8633060c41573]::dep_graph::dep_node::DepNode, rustc_middle[4fc8633060c41573]::dep_graph::serialized::SerializedDepNodeIndex)>>::call_once
9: 0x11215c2a4 - <rustc_middle[4fc8633060c41573]::dep_graph::graph::DepGraphData>::try_mark_previous_green
10: 0x11215c258 - <rustc_middle[4fc8633060c41573]::dep_graph::graph::DepGraphData>::try_mark_previous_green
11: 0x11215c258 - <rustc_middle[4fc8633060c41573]::dep_graph::graph::DepGraphData>::try_mark_previous_green
12: 0x11215c118 - <rustc_middle[4fc8633060c41573]::dep_graph::graph::DepGraphData>::try_mark_green
13: 0x112a38744 - rustc_query_impl[95864d7e07eebc26]::execution::ensure_can_skip_execution::<rustc_data_structures[abfc8eabe9c905b9]::vec_cache::VecCache<rustc_hir_id[185bbc009e60d6cf]::OwnerId, rustc_middle[4fc8633060c41573]::query::erase::ErasedData<[u8; 8usize]>, rustc_middle[4fc8633060c41573]::dep_graph::graph::DepNodeIndex>>
14: 0x112b3c800 - rustc_query_impl[95864d7e07eebc26]::query_impl::check_unsafety::execute_query_incr::__rust_end_short_backtrace
15: 0x111cbff88 - <rustc_middle[4fc8633060c41573]::ty::context::TyCtxt>::par_hir_body_owners::<rustc_interface[4d5dd335d36b1423]::passes::run_required_analyses::{closure#2}::{closure#0}>::{closure#0}
16: 0x111d06540 - rustc_interface[4d5dd335d36b1423]::passes::analysis
17: 0x1129b7a60 - rustc_query_impl[95864d7e07eebc26]::execution::try_execute_query::<rustc_middle[4fc8633060c41573]::query::caches::SingleCache<rustc_middle[4fc8633060c41573]::query::erase::ErasedData<[u8; 0usize]>>, true>
18: 0x112b6e930 - rustc_query_impl[95864d7e07eebc26]::query_impl::analysis::execute_query_incr::__rust_end_short_backtrace
19: 0x111366440 - rustc_interface[4d5dd335d36b1423]::passes::create_and_enter_global_ctxt::<core[65d2295b482aced]::option::Option<rustc_interface[4d5dd335d36b1423]::queries::Linker>, rustc_driver_impl[a9b8195e93143871]::run_compiler::{closure#0}::{closure#2}>
20: 0x1113addc0 - rustc_interface[4d5dd335d36b1423]::interface::run_compiler::<(), rustc_driver_impl[a9b8195e93143871]::run_compiler::{closure#0}>::{closure#1}
21: 0x1113a5948 - std[cc2a4db2680813b8]::sys::backtrace::__rust_begin_short_backtrace::<rustc_interface[4d5dd335d36b1423]::util::run_in_thread_with_globals<rustc_interface[4d5dd335d36b1423]::util::run_in_thread_pool_with_globals<rustc_interface[4d5dd335d36b1423]::interface::run_compiler<(), rustc_driver_impl[a9b8195e93143871]::run_compiler::{closure#0}>::{closure#1}, ()>::{closure#0}, ()>::{closure#0}::{closure#0}, ()>
22: 0x1113b5ad0 - <std[cc2a4db2680813b8]::thread::lifecycle::spawn_unchecked<rustc_interface[4d5dd335d36b1423]::util::run_in_thread_with_globals<rustc_interface[4d5dd335d36b1423]::util::run_in_thread_pool_with_globals<rustc_interface[4d5dd335d36b1423]::interface::run_compiler<(), rustc_driver_impl[a9b8195e93143871]::run_compiler::{closure#0}>::{closure#1}, ()>::{closure#0}, ()>::{closure#0}::{closure#0}, ()>::{closure#1} as core[65d2295b482aced]::ops::function::FnOnce<()>>::call_once::{shim:vtable#0}
23: 0x11353dee0 - <std[cc2a4db2680813b8]::sys::thread::unix::Thread>::new::thread_start
24: 0x18250fbc8 - __pthread_cond_wait
rustc version: 1.96.0-nightly (900485642 2026-04-08)
platform: aarch64-apple-darwin
query stack during panic:
#0 [analysis] running analysis passes on crate `---`
end of query stack
Backtrace
<backtrace>
Activity
[-][ICE]:[/-][+][ICE]: cannot decode `AttrId` with `CacheDecoder`[/+]spqr79 commentedon Apr 11, 2026
have you tried
cargo cleanfirst and then doing a fresh build? the panic inon_disk_cache.rs:663usually means the incremental cache has something itcan't decode anymore, and nightly builds can invalidate it without warning.
if the ICE comes back on the next incremental build after that, it's more
likely a regression in
900485642. in that case it would be worth tryingrustup override set nightly-2026-04-07to see if an earlier nightly avoidsit, since the
check_unsafetypath in the backtrace is a pretty specific cluefor bisecting.
ruriww commentedon Apr 11, 2026
I have cleaned, and I believe it was happening in the 04-05 build as well.
spqr79 commentedon Apr 11, 2026
Good to know it's not just stale cache. If 04-05 also triggers it, try nightly-2026-04-01 to narrow the window before bisecting.
ruriww commentedon Apr 12, 2026
Ok actually it is due to cache, but I wouldn't call it stale. Simply running two back to back builds after a clean consistently causes the error. 04-03 is the last version to work, 04-04 breaks.
spqr79 commentedon Apr 12, 2026
That's a precise reproduction. The window is tight enough that git log --oneline .. -- compiler/rustc_middle/src/query/on_disk_cache.rs might show the culprit directly without a full bisect.
JonathanBrouwer commentedon Apr 12, 2026
Duplicate of #154878, fixed by #155056