ICE In `rustc_mir::monomorphize::collector`

[HalfVoxel]

I'm getting an ICE when compiling some of my code.
Unfortunately, it has resisted all my attempts at producing a smaller code sample. It's very finicky.
I have uploaded a reproducible repo here: https://github.com/HalfVoxel/graphica/tree/rustc-replicate, unfortunately it's quite a lot of code. The code that seems to trigger it is this:

fn hash_material(material: &Material, changes: &[BindGroupEntryArc]) -> u64 {
    let mut hasher = std::collections::hash_map::DefaultHasher::default();
    std::ptr::hash(Arc::as_ptr(&material.bind_group_layout.0), &mut hasher);
    hasher.finish()
}

However, I have been unable to replicate it in a smaller project.

Meta

rustc --version --verbose:

rustc 1.55.0-nightly (ce1d5611a 2021-06-18)
binary: rustc
commit-hash: ce1d5611a28468663e275078649e7ca6eef735a8
commit-date: 2021-06-18
host: x86_64-unknown-linux-gnu
release: 1.55.0-nightly
LLVM version: 12.0.1

The bug exists both in the current nightly compiler and the current stable compiler.

Error output

thread 'rustc' panicked at 'called `Option::unwrap()` on a `None` value', compiler/rustc_mir/src/monomorphize/collector.rs:884:93

This is the location in rustc where it crashes:

Backtrace

<backtrace>

thread 'rustc' panicked at 'called `Option::unwrap()` on a `None` value', compiler/rustc_mir/src/monomorphize/collector.rs:884:93
stack backtrace:
   0: rust_begin_unwind
             at /rustc/ce1d5611a28468663e275078649e7ca6eef735a8/library/std/src/panicking.rs:515:5
   1: core::panicking::panic_fmt
             at /rustc/ce1d5611a28468663e275078649e7ca6eef735a8/library/core/src/panicking.rs:92:14
   2: core::panicking::panic
             at /rustc/ce1d5611a28468663e275078649e7ca6eef735a8/library/core/src/panicking.rs:50:5
   3: <rustc_mir::monomorphize::collector::MirNeighborCollector as rustc_middle::mir::visit::Visitor>::visit_terminator
   4: rustc_mir::monomorphize::collector::collect_neighbours
   5: rustc_mir::monomorphize::collector::collect_items_rec
   6: rustc_mir::monomorphize::collector::collect_items_rec
   7: rustc_mir::monomorphize::collector::collect_items_rec
   8: rustc_mir::monomorphize::collector::collect_items_rec
   9: rustc_mir::monomorphize::collector::collect_items_rec
  10: rustc_mir::monomorphize::collector::collect_items_rec
  11: rustc_mir::monomorphize::collector::collect_items_rec
  12: rustc_mir::monomorphize::collector::collect_items_rec
  13: rustc_mir::monomorphize::collector::collect_items_rec
  14: rustc_mir::monomorphize::collector::collect_items_rec
  15: rustc_mir::monomorphize::collector::collect_items_rec
  16: rustc_mir::monomorphize::collector::collect_items_rec
  17: rustc_session::utils::<impl rustc_session::session::Session>::time
  18: rustc_mir::monomorphize::collector::collect_crate_mono_items
  19: rustc_mir::monomorphize::partitioning::collect_and_partition_mono_items
  20: rustc_query_system::query::plumbing::get_query_impl
  21: <rustc_query_impl::Queries as rustc_middle::ty::query::QueryEngine>::collect_and_partition_mono_items
  22: rustc_codegen_ssa::back::symbol_export::exported_symbols_provider_local
  23: rustc_query_system::query::plumbing::get_query_impl
  24: <rustc_query_impl::Queries as rustc_middle::ty::query::QueryEngine>::exported_symbols
  25: rustc_metadata::rmeta::encoder::EncodeContext::encode_crate_root
  26: rustc_metadata::rmeta::encoder::encode_metadata_impl
  27: rustc_data_structures::sync::join
  28: rustc_metadata::rmeta::decoder::cstore_impl::<impl rustc_middle::middle::cstore::CrateStore for rustc_metadata::creader::CStore>::encode_metadata
  29: rustc_middle::ty::context::TyCtxt::encode_metadata
  30: rustc_interface::passes::QueryContext::enter
  31: rustc_interface::queries::Queries::ongoing_codegen
  32: rustc_interface::queries::<impl rustc_interface::interface::Compiler>::enter
  33: rustc_span::with_source_map
  34: rustc_interface::interface::create_compiler_and_run
  35: scoped_tls::ScopedKey<T>::set
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/issues/new?labels=C-bug%2C+I-ICE%2C+T-compiler&template=ice.md

note: rustc 1.55.0-nightly (ce1d5611a 2021-06-18) running on x86_64-unknown-linux-gnu

note: compiler flags: -C opt-level=z -C embed-bitcode=no --crate-type lib

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

query stack during panic:
#0 [collect_and_partition_mono_items] collect_and_partition_mono_items
#1 [exported_symbols] exported_symbols
end of query stack
</p>
</details>

[steffahn]

significantly reduced:

use std::ptr;

trait Context {
    type BindGroupLayoutId;
}
pub struct C;
pub struct BindGroupLayout {
    id: <C as Context>::BindGroupLayoutId,
}
impl Context for C {
    type BindGroupLayoutId = ();
}

pub fn main() {
    let y: *const BindGroupLayout = ptr::null();

    let mut hasher = std::collections::hash_map::DefaultHasher::default();
    std::ptr::hash(y, &mut hasher);
}

[steffahn]

Without using DefaultHasher or std

trait Trait {
    type Associated;
}
pub struct T;
impl Trait for T {
    type Associated = ();
}
pub struct Struct {
    _field: <T as Trait>::Associated,
}

struct H;
impl core::hash::Hasher for H {
    fn finish(&self) -> u64 {
        todo!()
    }
    fn write(&mut self, _: &[u8]) {
        todo!()
    }
}

pub fn main() {
    let y: *const Struct = core::ptr::null();
    core::hash::Hash::hash(&y, &mut H);
}

[steffahn]

Unwrapping the core internals you can get this repro:

#![feature(ptr_metadata)]

use core::ptr::Pointee;
trait Trait {
    type Associated;
}
pub struct T;
impl Trait for T {
    type Associated = ();
}
pub struct Struct {
    _field: <T as Trait>::Associated,
}

struct H;
impl core::hash::Hasher for H {
    fn finish(&self) -> u64 {
        todo!()
    }
    fn write(&mut self, _: &[u8]) {
        todo!()
    }
}

fn panic<T>() -> T {
    panic!()
}

pub fn main() {
    use core::hash::Hash;
    let metadata: <Struct as Pointee>::Metadata = panic();
    metadata.hash(&mut H);
}

Or using something other than Hash methods

#![feature(ptr_metadata)]

use core::ptr::Pointee;
trait Trait {
    type Associated;
}
pub struct T;
impl Trait for T {
    type Associated = ();
}
pub struct Struct {
    _field: <T as Trait>::Associated,
}


fn panic<T>() -> T {
    panic!()
}

pub fn main() {
    let metadata: <Struct as Pointee>::Metadata = panic();
    metadata == metadata;
}

With no usage at all, the ICE changes:

#![feature(ptr_metadata)]

use core::ptr::Pointee;
trait Trait {
    type Associated;
}
pub struct T;
impl Trait for T {
    type Associated = ();
}
pub struct Struct {
    _field: <T as Trait>::Associated,
}

pub fn main() {
    let _x: <Struct as Pointee>::Metadata;
}

error: internal compiler error: compiler/rustc_codegen_llvm/src/debuginfo/metadata.rs:704:14: debuginfo: unexpected type in type_metadata: <Struct as std::ptr::Pointee>::Metadata

thread 'rustc' panicked at 'Box<dyn Any>', compiler/rustc_errors/src/lib.rs:1007:9
note: run with `RUST_BACKTRACE=1` environment variable to display a backtrace

note: 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: rustc 1.55.0-nightly (a85f584ae 2021-06-16) running on x86_64-unknown-linux-gnu

note: compiler flags: -C embed-bitcode=no -C debuginfo=2 -C incremental --crate-type bin

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

query stack during panic:
end of query stack
error: aborting due to previous error

[steffahn]

Bisecting #86469 (comment), regression at: d1462d8, which is #81172, cc @SimonSapin.

This issue is a recent regression (stable 1.52), turning previously compiling, valid code into an ICE.

@rustbot label -E-needs-mcve, regression-from-stable-to-stable.

[rustbot]

Error: Label needs-mcve can only be set by Rust team members

Please let @rust-lang/release know if you're having trouble with this bot.

[steffahn]

Looks like this is a duplicate of #85447

[apiraino]

great job with the analysis and bisection, thanks @steffahn !

I'm gonna close as duplicate but (as always) feel free to reopen if it's not the case

@rustbot label -I-prioritize