rust-lang / rust-lang/rust

ICE (delayed): broken MIR in DefId(...) (...): bad assignment (...): NoSolution

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C-bug I-ICE S-bug-has-test T-compiler T-types
Dominant language
Rust
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PR metrics pending

Description

Code

(one file: "ice-mwe.rs")

use std::ops::Add;

pub trait TimesTwo
   where *const Self: Add<*const Self>,
{
   extern "C" fn t2_ptr(slf: *const Self)
   -> <*const Self as Add<*const Self>>::Output {
       slf + slf
   }
}

fn main(){}
Meta

rustc --version --verbose:

rustc 1.85.0-nightly (9e136a30a 2024-12-19)
binary: rustc
commit-hash: 9e136a30a965bf4e63f03095c57df7257bf96fd6
commit-date: 2024-12-19
host: x86_64-unknown-linux-gnu
release: 1.85.0-nightly
LLVM version: 19.1.6
Error output

(exact command used: rustc path/to/ice-mwe.rs)

note: no errors encountered even though delayed bugs were created

note: those delayed bugs will now be shown as internal compiler errors

error: internal compiler error: broken MIR in DefId(0:5 ~ ice_mwe[fdb9]::TimesTwo::t2_ptr) (_0 = Add(move _2, move _3)): bad assignment (Alias(Projection, AliasTy { args: [*const Self/#0, *const Self/#0], def_id: DefId(2:3495 ~ core[57d6]::ops::arith::Add::Output), .. }) = *const Self/#0): NoSolution
 --> src/ice-mwe.rs:8:8
  |
8 |        slf + slf
  |        ^^^^^^^^^
  |
note: delayed at compiler/rustc_borrowck/src/type_check/mod.rs:1157:21 - disabled backtrace
 --> src/ice-mwe.rs:8:8
  |
8 |        slf + slf
  |        ^^^^^^^^^

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/niac/tmp/mwe/rustc-ice-2024-12-20T22_57_23-3180020.txt` to your bug report

query stack during panic:
end of query stack
Backtrace

(exact command used: RUST_BACKTRACE=1 rustc path/to/ice-mwe.rs)
(also downloadable as rustc-ice-2024-12-20T22_54_18-3179078.txt)

note: no errors encountered even though delayed bugs were created

note: those delayed bugs will now be shown as internal compiler errors

error: internal compiler error: broken MIR in DefId(0:5 ~ ice_mwe[fdb9]::TimesTwo::t2_ptr) (_0 = Add(move _2, move _3)): bad assignment (Alias(Projection, AliasTy { args: [*const Self/#0, *const Self/#0], def_id: DefId(2:3495 ~ core[57d6]::ops::arith::Add::Output), .. }) = *const Self/#0): NoSolution
 --> src/ice-mwe.rs:8:8
  |
8 |        slf + slf
  |        ^^^^^^^^^
  |
note: delayed at compiler/rustc_borrowck/src/type_check/mod.rs:1157:21
         0: <rustc_errors::DiagCtxtInner>::emit_diagnostic
         1: <rustc_errors::DiagCtxtHandle>::emit_diagnostic
         2: <rustc_span::ErrorGuaranteed as rustc_errors::diagnostic::EmissionGuarantee>::emit_producing_guarantee
         3: <rustc_errors::DiagCtxtHandle>::span_delayed_bug::<rustc_span::span_encoding::Span, alloc::string::String>
         4: <rustc_borrowck::type_check::TypeChecker>::typeck_mir
         5: rustc_borrowck::type_check::type_check
         6: rustc_borrowck::nll::compute_regions
         7: rustc_borrowck::do_mir_borrowck
         8: rustc_query_impl::plumbing::__rust_begin_short_backtrace::<rustc_query_impl::query_impl::mir_borrowck::dynamic_query::{closure#2}::{closure#0}, rustc_middle::query::erase::Erased<[u8; 8]>>
         9: rustc_query_system::query::plumbing::try_execute_query::<rustc_query_impl::DynamicConfig<rustc_data_structures::vec_cache::VecCache<rustc_span::def_id::LocalDefId, rustc_middle::query::erase::Erased<[u8; 8]>, rustc_query_system::dep_graph::graph::DepNodeIndex>, false, false, false>, rustc_query_impl::plumbing::QueryCtxt, false>
        10: rustc_query_impl::query_impl::mir_borrowck::get_query_non_incr::__rust_end_short_backtrace
        11: rustc_interface::passes::run_required_analyses
        12: rustc_interface::passes::analysis
        13: rustc_query_impl::plumbing::__rust_begin_short_backtrace::<rustc_query_impl::query_impl::analysis::dynamic_query::{closure#2}::{closure#0}, rustc_middle::query::erase::Erased<[u8; 0]>>
        14: rustc_query_system::query::plumbing::try_execute_query::<rustc_query_impl::DynamicConfig<rustc_query_system::query::caches::SingleCache<rustc_middle::query::erase::Erased<[u8; 0]>>, false, false, false>, rustc_query_impl::plumbing::QueryCtxt, false>
        15: rustc_query_impl::query_impl::analysis::get_query_non_incr::__rust_end_short_backtrace
        16: 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}
        17: rustc_interface::interface::run_compiler::<(), rustc_driver_impl::run_compiler::{closure#0}>::{closure#1}
        18: std::sys::backtrace::__rust_begin_short_backtrace::<rustc_interface::util::run_in_thread_with_globals<rustc_interface::util::run_in_thread_pool_with_globals<rustc_interface::interface::run_compiler<(), rustc_driver_impl::run_compiler::{closure#0}>::{closure#1}, ()>::{closure#0}, ()>::{closure#0}::{closure#0}, ()>
        19: <<std::thread::Builder>::spawn_unchecked_<rustc_interface::util::run_in_thread_with_globals<rustc_interface::util::run_in_thread_pool_with_globals<rustc_interface::interface::run_compiler<(), rustc_driver_impl::run_compiler::{closure#0}>::{closure#1}, ()>::{closure#0}, ()>::{closure#0}::{closure#0}, ()>::{closure#1} as core::ops::function::FnOnce<()>>::call_once::{shim:vtable#0}
        20: std::sys::pal::unix::thread::Thread::new::thread_start
        21: start_thread
        22: clone3
 --> src/ice-mwe.rs:8:8
  |
8 |        slf + slf
  |        ^^^^^^^^^

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/niac/tmp/mwe/rustc-ice-2024-12-20T22_54_18-3179078.txt` to your bug report

query stack during panic:
end of query stack

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 one-file reproducer in ice-mwe.rs with the reported rustc command and confirm whether the ICE still occurs on a current compiler. Then inspect compiler/rustc_borrowck/src/type_check/mod.rs at the reported line and trace the MIR type-checking path; done means the reproducer no longer produces this internal compiler error, with a regression test if the relevant test location is identified.

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
Stale
Clarity
Needs clarification
Newbie friendliness
30/100

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