thread 'rustc' panicked at 'Failed to get parent for DefId(0:3721 ~ std[c8fe]::panic[0]::{{impl}}[20])', src/librustc_middle/traits/specialization_graph.rs:46:52

[bjorn3]

Steps to reproduce:

1. Apply the patches at https://github.com/bjorn3/rustc_codegen_cranelift/blob/c03e824db78c83d2c5c37d37c45d2dcc964eca3f/patches to the standard library source.
2. Compile it

error[E0432]: unresolved import `core::num::NonZeroI128`
  --> sysroot_src/src/libstd/num.rs:15:21
   |
15 | pub use core::num::{NonZeroI128, NonZeroI16, NonZeroI32, NonZeroI64, NonZeroI8, NonZeroIsize};
   |                     ^^^^^^^^^^^
   |                     |
   |                     no `NonZeroI128` in `num`
   |                     help: a similar name exists in the module: `NonZeroI8`

error[E0432]: unresolved import `core::num::NonZeroU128`
  --> sysroot_src/src/libstd/num.rs:17:21
   |
17 | pub use core::num::{NonZeroU128, NonZeroU16, NonZeroU32, NonZeroU64, NonZeroU8, NonZeroUsize};
   |                     ^^^^^^^^^^^
   |                     |
   |                     no `NonZeroU128` in `num`
   |                     help: a similar name exists in the module: `NonZeroU8`

error[E0412]: cannot find type `AtomicI128` in module `atomic`
    --> sysroot_src/src/libstd/panic.rs:258:32
     |
258  | impl RefUnwindSafe for atomic::AtomicI128 {}
     |                                ^^^^^^^^^^ help: a struct with a similar name exists: `AtomicI16`
     | 
    ::: /home/bjorn/Documenten/cg_clif/build_sysroot/sysroot_src/src/libcore/sync/atomic.rs:1229:9
     |
1229 |         pub struct $atomic_type {
     |         ----------------------- similarly named struct `AtomicI16` defined here

error[E0412]: cannot find type `AtomicU128` in module `atomic`
    --> sysroot_src/src/libstd/panic.rs:277:32
     |
277  | impl RefUnwindSafe for atomic::AtomicU128 {}
     |                                ^^^^^^^^^^ help: a struct with a similar name exists: `AtomicU16`
     | 
    ::: /home/bjorn/Documenten/cg_clif/build_sysroot/sysroot_src/src/libcore/sync/atomic.rs:1229:9
     |
1229 |         pub struct $atomic_type {
     |         ----------------------- similarly named struct `AtomicU16` defined here

thread 'rustc' panicked at 'Failed to get parent for DefId(0:3721 ~ std[c8fe]::panic[0]::{{impl}}[20])', src/librustc_middle/traits/specialization_graph.rs:46:52
stack backtrace:
   0: backtrace::backtrace::libunwind::trace
             at /cargo/registry/src/github.com-1ecc6299db9ec823/backtrace-0.3.46/src/backtrace/libunwind.rs:86
   1: backtrace::backtrace::trace_unsynchronized
             at /cargo/registry/src/github.com-1ecc6299db9ec823/backtrace-0.3.46/src/backtrace/mod.rs:66
   2: std::sys_common::backtrace::_print_fmt
             at src/libstd/sys_common/backtrace.rs:78
   3: <std::sys_common::backtrace::_print::DisplayBacktrace as core::fmt::Display>::fmt
             at src/libstd/sys_common/backtrace.rs:59
   4: core::fmt::write
             at src/libcore/fmt/mod.rs:1069
   5: std::io::Write::write_fmt
             at src/libstd/io/mod.rs:1504
   6: std::sys_common::backtrace::_print
             at src/libstd/sys_common/backtrace.rs:62
   7: std::sys_common::backtrace::print
             at src/libstd/sys_common/backtrace.rs:49
   8: std::panicking::default_hook::{{closure}}
             at src/libstd/panicking.rs:198
   9: std::panicking::default_hook
             at src/libstd/panicking.rs:218
  10: rustc_driver::report_ice
  11: std::panicking::rust_panic_with_hook
             at src/libstd/panicking.rs:515
  12: rust_begin_unwind
             at src/libstd/panicking.rs:419
  13: std::panicking::begin_panic_fmt
             at src/libstd/panicking.rs:373
  14: rustc_middle::traits::specialization_graph::Graph::parent::{{closure}}
  15: rustc_middle::traits::specialization_graph::Graph::parent
  16: <rustc_middle::traits::specialization_graph::Ancestors as core::iter::traits::iterator::Iterator>::next
  17: rustc_typeck::impl_wf_check::min_specialization::check_min_specialization
  18: <rustc_typeck::impl_wf_check::ImplWfCheck as rustc_hir::itemlikevisit::ItemLikeVisitor>::visit_item
  19: rustc_middle::hir::map::Map::visit_item_likes_in_module
  20: rustc_typeck::impl_wf_check::check_mod_impl_wf
  21: rustc_middle::ty::query::<impl rustc_query_system::query::config::QueryAccessors<rustc_middle::ty::context::TyCtxt> for rustc_middle::ty::query::queries::check_mod_impl_wf>::compute
  22: rustc_middle::dep_graph::<impl rustc_query_system::dep_graph::DepKind for rustc_middle::dep_graph::dep_node::DepKind>::with_deps
  23: rustc_query_system::dep_graph::graph::DepGraph<K>::with_task_impl
  24: rustc_query_system::query::plumbing::get_query
  25: rustc_query_system::query::plumbing::ensure_query
  26: rustc_typeck::impl_wf_check::impl_wf_check
  27: rustc_typeck::check_crate
  28: rustc_interface::passes::analysis
  29: rustc_middle::ty::query::<impl rustc_query_system::query::config::QueryAccessors<rustc_middle::ty::context::TyCtxt> for rustc_middle::ty::query::queries::analysis>::compute
  30: rustc_middle::dep_graph::<impl rustc_query_system::dep_graph::DepKind for rustc_middle::dep_graph::dep_node::DepKind>::with_deps
  31: rustc_query_system::dep_graph::graph::DepGraph<K>::with_task_impl
  32: rustc_query_system::query::plumbing::get_query
  33: rustc_middle::ty::context::tls::enter_global
  34: rustc_interface::interface::run_compiler_in_existing_thread_pool
  35: scoped_tls::ScopedKey<T>::set
  36: rustc_ast::attr::with_globals
note: Some details are omitted, run with `RUST_BACKTRACE=full` for a verbose backtrace.

error: internal compiler error: unexpected panic

note: the compiler unexpectedly panicked. this is a bug.

note: we would appreciate a bug report: https://github.com/rust-lang/rust/blob/master/CONTRIBUTING.md#bug-reports

note: rustc 1.44.0-nightly (3712e11a8 2020-04-12) running on x86_64-unknown-linux-gnu

note: compiler flags: -Z panic-abort-tests -Z codegen-backend=/home/bjorn/Documenten/cg_clif/target/release/librustc_codegen_cranelift.so -Z force-unstable-if-unmarked -C prefer-dynamic -C debuginfo=2 -C incremental -C linker=aarch64-linux-gnu-gcc -C panic=abort -C debuginfo=2 --crate-type dylib --crate-type rlib

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

query stack during panic:
#0 [check_mod_impl_wf] checking that impls are well-formed in module `panic`
#1 [analysis] running analysis passes on this crate
end of query stack
error: aborting due to 4 previous errors

(keep alive: bjorn3/rustc_codegen_cranelift@c03e824)

[steffahn]

I'm having trouble reproducing this. Could you be more specific about what version of the standard library source to use and how exactly to compile it?

[lcnr]

@bjorn3 I've fixed a similar bug in #74483, which had the same error (noticed by @JohnTitor), can you still reproduce this issue?

edit: sorry for pinging you @ bjorn

[bjorn3]

can you still reproduce this issue?

I am pretty sure that the patches to libcore that reproduced this error no longer apply.

edit: sorry for pinging you @ bjorn

It's fine to ping me.

[lcnr]

I originally pinged @ bjorn without the 3 at the end 😅

Hmm, then there isn't much to do here I think... will go ahead and close this as I expect #74516 to have fixed this