rust-lang / rust-lang/rust

ICE `Normalizing .. without wrapping in a .. Binder`

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C-bug F-generic_const_parameter_types F-unsized_const_params I-ICE S-has-mcve T-compiler
Dominant language
Rust
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Description

auto-reduced (treereduce-rust):

#![feature(generic_const_parameter_types)]

struct Bar<'a, const N: &'a u32>;
fn foo(&self) -> Bar<0> {
    todo!();
}

original:

#![feature(generic_const_parameter_types)]
#![feature(unsized_const_params)]
#![feature(unsized_const_params)]

struct Bar<'a, const N: &'a u32>;
fn foo(&self) -> Bar<0> { todo!(); }

pub fn main() {}

Version information

rustc 1.92.0-nightly (dd7fda570 2025-09-20)
binary: rustc
commit-hash: dd7fda570040e8a736f7d8bc28ddd1b444aabc82
commit-date: 2025-09-20
host: x86_64-unknown-linux-gnu
release: 1.92.0-nightly
LLVM version: 21.1.1

Command:
/home/matthias/.rustup/toolchains/master/bin/rustc

Program output 

error: `self` parameter is only allowed in associated functions
 --> /tmp/icemaker_global_tempdir.thpkJ4fkiPJl/rustc_testrunner_tmpdir_reporting.vfQda4Joev2S/mvce.rs:4:8
  |
4 | fn foo(&self) -> Bar<0> {
  |        ^^^^^ not semantically valid as function parameter
  |
  = note: associated functions are those in `impl` or `trait` definitions

warning: the feature `generic_const_parameter_types` is incomplete and may not be safe to use and/or cause compiler crashes
 --> /tmp/icemaker_global_tempdir.thpkJ4fkiPJl/rustc_testrunner_tmpdir_reporting.vfQda4Joev2S/mvce.rs:1:12
  |
1 | #![feature(generic_const_parameter_types)]
  |            ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
  |
  = note: see issue #137626 <https://github.com/rust-lang/rust/issues/137626> for more information
  = note: `#[warn(incomplete_features)]` on by default

error[E0601]: `main` function not found in crate `mvce`
 --> /tmp/icemaker_global_tempdir.thpkJ4fkiPJl/rustc_testrunner_tmpdir_reporting.vfQda4Joev2S/mvce.rs:6:2
  |
6 | }
  |  ^ consider adding a `main` function to `/tmp/icemaker_global_tempdir.thpkJ4fkiPJl/rustc_testrunner_tmpdir_reporting.vfQda4Joev2S/mvce.rs`

error[E0392]: lifetime parameter `'a` is never used
 --> /tmp/icemaker_global_tempdir.thpkJ4fkiPJl/rustc_testrunner_tmpdir_reporting.vfQda4Joev2S/mvce.rs:3:12
  |
3 | struct Bar<'a, const N: &'a u32>;
  |            ^^ unused lifetime parameter
  |
  = help: consider removing `'a`, referring to it in a field, or using a marker such as `PhantomData`

error: `&'a u32` is forbidden as the type of a const generic parameter
 --> /tmp/icemaker_global_tempdir.thpkJ4fkiPJl/rustc_testrunner_tmpdir_reporting.vfQda4Joev2S/mvce.rs:3:25
  |
3 | struct Bar<'a, const N: &'a u32>;
  |                         ^^^^^^^
  |
  = note: the only supported types are integers, `bool`, and `char`
help: add `#![feature(adt_const_params)]` to the crate attributes to enable more complex and user defined types
  |
3 + #![feature(adt_const_params)]
  |
help: add `#![feature(unsized_const_params)]` to the crate attributes to enable references to implement the `ConstParamTy` trait
  |
3 + #![feature(unsized_const_params)]
  |


thread 'rustc' (3574067) panicked at /rustc-dev/dd7fda570040e8a736f7d8bc28ddd1b444aabc82/compiler/rustc_trait_selection/src/traits/normalize.rs:172:9:
Normalizing &'^0.Named(DefId(0:9 ~ mvce[a7ac]::foo::'_)) u32 without wrapping in a `Binder`
stack backtrace:
   0:     0x7fc536e02983 - <std::sys::backtrace::BacktraceLock::print::DisplayBacktrace as core::fmt::Display>::fmt::h7c6ba7eb3d79c74e
   1:     0x7fc537602044 - core::fmt::write::h51b415dc740abb61
   2:     0x7fc536db7201 - std::io::Write::write_fmt::h65024e6b411b5d6a
   3:     0x7fc536dc86f2 - std::sys::backtrace::BacktraceLock::print::h1fa141d4115fcdc7
   4:     0x7fc536dce659 - std::panicking::default_hook::{{closure}}::h5b8d1bafc007debc
   5:     0x7fc536dce183 - std::panicking::default_hook::hbee1bd2db26bedfe
   6:     0x7fc535df23c7 - std[aa543e5c3b33e14e]::panicking::update_hook::<alloc[25bb32ac37752f7b]::boxed::Box<rustc_driver_impl[4e82038d4654c963]::install_ice_hook::{closure#1}>>::{closure#0}
   7:     0x7fc536dcea7f - std::panicking::panic_with_hook::h8cbd8c4377e6572b
   8:     0x7fc536dce83a - std::panicking::panic_handler::{{closure}}::h335ded1aca77b6b6
   9:     0x7fc536dc8839 - std::sys::backtrace::__rust_end_short_backtrace::hd229ab5df32e8172
  10:     0x7fc536da936d - __rustc[8ed8e68a5aa5849d]::rust_begin_unwind
  11:     0x7fc533df3dd0 - core::panicking::panic_fmt::hb55754338c38e2ee
  12:     0x7fc537937879 - <rustc_hir_typeck[135be1f05852888c]::fn_ctxt::FnCtxt>::normalize::<rustc_middle[224366ec5639bfdc]::ty::Ty>
  13:     0x7fc5379e4ec8 - rustc_hir_typeck[135be1f05852888c]::typeck_with_inspect::{closure#0}
  14:     0x7fc5379dfcf6 - rustc_query_impl[c74c6a12e169b097]::plumbing::__rust_begin_short_backtrace::<rustc_query_impl[c74c6a12e169b097]::query_impl::typeck::dynamic_query::{closure#2}::{closure#0}, rustc_middle[224366ec5639bfdc]::query::erase::Erased<[u8; 8usize]>>
  15:     0x7fc537801344 - rustc_query_system[dabb8f7ac9ad8702]::query::plumbing::try_execute_query::<rustc_query_impl[c74c6a12e169b097]::DynamicConfig<rustc_data_structures[2c2d92c6a626fca3]::vec_cache::VecCache<rustc_span[201c3f2d192352b6]::def_id::LocalDefId, rustc_middle[224366ec5639bfdc]::query::erase::Erased<[u8; 8usize]>, rustc_query_system[dabb8f7ac9ad8702]::dep_graph::graph::DepNodeIndex>, false, false, false>, rustc_query_impl[c74c6a12e169b097]::plumbing::QueryCtxt, false>
  16:     0x7fc537800cc9 - rustc_query_impl[c74c6a12e169b097]::query_impl::typeck::get_query_non_incr::__rust_end_short_backtrace
  17:     0x7fc537802195 - rustc_query_impl[c74c6a12e169b097]::plumbing::__rust_begin_short_backtrace::<rustc_query_impl[c74c6a12e169b097]::query_impl::used_trait_imports::dynamic_query::{closure#2}::{closure#0}, rustc_middle[224366ec5639bfdc]::query::erase::Erased<[u8; 8usize]>>
  18:     0x7fc537801344 - rustc_query_system[dabb8f7ac9ad8702]::query::plumbing::try_execute_query::<rustc_query_impl[c74c6a12e169b097]::DynamicConfig<rustc_data_structures[2c2d92c6a626fca3]::vec_cache::VecCache<rustc_span[201c3f2d192352b6]::def_id::LocalDefId, rustc_middle[224366ec5639bfdc]::query::erase::Erased<[u8; 8usize]>, rustc_query_system[dabb8f7ac9ad8702]::dep_graph::graph::DepNodeIndex>, false, false, false>, rustc_query_impl[c74c6a12e169b097]::plumbing::QueryCtxt, false>
  19:     0x7fc537800c09 - rustc_query_impl[c74c6a12e169b097]::query_impl::used_trait_imports::get_query_non_incr::__rust_end_short_backtrace
  20:     0x7fc5378022c7 - rustc_hir_analysis[84156159369fd08e]::check_unused::check_unused_traits
  21:     0x7fc5378021c7 - rustc_query_impl[c74c6a12e169b097]::plumbing::__rust_begin_short_backtrace::<rustc_query_impl[c74c6a12e169b097]::query_impl::check_unused_traits::dynamic_query::{closure#2}::{closure#0}, rustc_middle[224366ec5639bfdc]::query::erase::Erased<[u8; 0usize]>>
  22:     0x7fc5385c2a60 - rustc_query_system[dabb8f7ac9ad8702]::query::plumbing::try_execute_query::<rustc_query_impl[c74c6a12e169b097]::DynamicConfig<rustc_query_system[dabb8f7ac9ad8702]::query::caches::SingleCache<rustc_middle[224366ec5639bfdc]::query::erase::Erased<[u8; 0usize]>>, false, false, false>, rustc_query_impl[c74c6a12e169b097]::plumbing::QueryCtxt, false>
  23:     0x7fc5385c27c2 - rustc_query_impl[c74c6a12e169b097]::query_impl::check_unused_traits::get_query_non_incr::__rust_end_short_backtrace
  24:     0x7fc538043341 - rustc_hir_analysis[84156159369fd08e]::check_crate
  25:     0x7fc537802a30 - rustc_interface[ddde8db7de1554b0]::passes::analysis
  26:     0x7fc5378026ed - rustc_query_impl[c74c6a12e169b097]::plumbing::__rust_begin_short_backtrace::<rustc_query_impl[c74c6a12e169b097]::query_impl::analysis::dynamic_query::{closure#2}::{closure#0}, rustc_middle[224366ec5639bfdc]::query::erase::Erased<[u8; 0usize]>>
  27:     0x7fc5385c2a60 - rustc_query_system[dabb8f7ac9ad8702]::query::plumbing::try_execute_query::<rustc_query_impl[c74c6a12e169b097]::DynamicConfig<rustc_query_system[dabb8f7ac9ad8702]::query::caches::SingleCache<rustc_middle[224366ec5639bfdc]::query::erase::Erased<[u8; 0usize]>>, false, false, false>, rustc_query_impl[c74c6a12e169b097]::plumbing::QueryCtxt, false>
  28:     0x7fc5385c26b6 - rustc_query_impl[c74c6a12e169b097]::query_impl::analysis::get_query_non_incr::__rust_end_short_backtrace
  29:     0x7fc5389027cf - rustc_interface[ddde8db7de1554b0]::passes::create_and_enter_global_ctxt::<core[e1f2d92e823976a5]::option::Option<rustc_interface[ddde8db7de1554b0]::queries::Linker>, rustc_driver_impl[4e82038d4654c963]::run_compiler::{closure#0}::{closure#2}>::{closure#2}::{closure#0}
  30:     0x7fc53881643e - rustc_interface[ddde8db7de1554b0]::interface::run_compiler::<(), rustc_driver_impl[4e82038d4654c963]::run_compiler::{closure#0}>::{closure#1}
  31:     0x7fc538797db8 - std[aa543e5c3b33e14e]::sys::backtrace::__rust_begin_short_backtrace::<rustc_interface[ddde8db7de1554b0]::util::run_in_thread_with_globals<rustc_interface[ddde8db7de1554b0]::util::run_in_thread_pool_with_globals<rustc_interface[ddde8db7de1554b0]::interface::run_compiler<(), rustc_driver_impl[4e82038d4654c963]::run_compiler::{closure#0}>::{closure#1}, ()>::{closure#0}, ()>::{closure#0}::{closure#0}, ()>
  32:     0x7fc538797a88 - <<std[aa543e5c3b33e14e]::thread::Builder>::spawn_unchecked_<rustc_interface[ddde8db7de1554b0]::util::run_in_thread_with_globals<rustc_interface[ddde8db7de1554b0]::util::run_in_thread_pool_with_globals<rustc_interface[ddde8db7de1554b0]::interface::run_compiler<(), rustc_driver_impl[4e82038d4654c963]::run_compiler::{closure#0}>::{closure#1}, ()>::{closure#0}, ()>::{closure#0}::{closure#0}, ()>::{closure#1} as core[e1f2d92e823976a5]::ops::function::FnOnce<()>>::call_once::{shim:vtable#0}
  33:     0x7fc53879ddcd - std::sys::thread::unix::Thread::new::thread_start::ha9de35456108e0f3
  34:     0x7fc531e969cb - <unknown>
  35:     0x7fc531f1aa0c - <unknown>
  36:                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: rustc 1.92.0-nightly (dd7fda570 2025-09-20) running on x86_64-unknown-linux-gnu

query stack during panic:
#0 [typeck] type-checking `foo::{constant#0}`
#1 [used_trait_imports] finding used_trait_imports `foo::{constant#0}`
#2 [check_unused_traits] checking unused trait imports in crate
#3 [analysis] running analysis passes on this crate
end of query stack
error: aborting due to 4 previous errors; 1 warning emitted

Some errors have detailed explanations: E0392, E0601.
For more information about an error, try `rustc --explain E0392`.

@rustbot label +F-generic_const_parameter_types +F-unsized_const_params +F-unsized_const_params

Contributor guide

Open the contributing guide

First steps

  1. Read the whole issue, then the project's contributing guide.
  2. Comment on the issue to say you are picking it up — it saves two people doing the same work.
  3. Fork the repository and make your change on a branch.
  4. Open a pull request that references the issue number.

Research direction

Start by compiling the reduced Rust example from the issue with the reported nightly and inspect compiler/rustc_trait_selection/src/traits/normalize.rs:172. Trace the type-checking path shown in the query stack, then verify that the example reports diagnostics without an internal compiler error. The issue does not name a regression-test location.

Written by the indexing model from the issue text.

Assessment

Tech stack
rust
Domain
compilers
Issue type
Bug
Difficulty
4/5
Estimated time
3-5 days
Activity status
Quiet
Clarity
Mostly clear
Newbie friendliness
48/100

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