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

[niacdoial]

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

[cyrgani]

Reduced:

use std::ops::Add;

pub fn foo<T>(slf: *const T)
where
    *const T: Add,
{
    slf + slf;
}

[niacdoial]

It also gives a different stack trace when using this variation of the reduced input. (and the ICE is no longer "delayed").
I think they likely have the same cause, but I can easily move this to a separate issue if need be.

use std::ops::Add;

pub fn foo<T>(slf: *const T)
where
    *const T: Add<u8>,
{
    slf + 1_u8;
}

(attached: the log file produced by running RUST_BACKTRACE=1 rustc on that new example (give or take a fn main(){} line))

[niacdoial]

cargo bisect-rust can't get nightlies that far but...
this seems like a regression that took place somewhere between rust 1.1 and rust 1.2 :wheeze:
I'll continue the bisection from source (if that's possible) some other time

[saethlin]

Bisecting back that far is unlikely to be useful because the compiler codebase has changed so much since then.