[ICE]: monomorphization failure

Code

// no idea how to minimize this one; it doesn't happen when i start paring things down, but i have
// committed it in a branch in case you want to see the horrors

Meta

Crashes similarly in all of the below:
rustc --version --verbose:

rustc 1.98.0-nightly (c397dae80 2026-07-02)
binary: rustc
commit-hash: c397dae808f70caebab1fc4e11b3edf7e59f58c7
commit-date: 2026-07-02
host: x86_64-unknown-linux-gnu
release: 1.98.0-nightly
LLVM version: 22.1.8

rustc 1.97.0-beta.6 (b2282dd56 2026-07-01)
binary: rustc
commit-hash: b2282dd5646a57d570fc86fbe8df0e8826665ef6
commit-date: 2026-07-01
host: x86_64-unknown-linux-gnu
release: 1.97.0-beta.6
LLVM version: 22.1.6

rustc 1.96.1 (31fca3adb 2026-06-26)
binary: rustc
commit-hash: 31fca3adb283cc9dfd56b49cdee9a96eb9c96ffd
commit-date: 2026-06-26
host: x86_64-unknown-linux-gnu
release: 1.96.1
LLVM version: 22.1.2

rustc 1.65.0 (897e37553 2022-11-02)
binary: rustc
commit-hash: 897e37553bba8b42751c67658967889d11ecd120
commit-date: 2022-11-02
host: x86_64-unknown-linux-gnu
release: 1.65.0
LLVM version: 15.0.0

Error output

from stable:

query stack during panic:
#0 [items_of_instance] collecting items used by `_::_::<impl at examples/schema.rs:15:35: 15:42>::register::{closure#0}`
#1 [collect_and_partition_mono_items] collect_and_partition_mono_items
end of query stack
error: could not compile `bilrost` (example "schema")

Caused by:
  process didn't exit successfully: `/home/widders/.rustup/toolchains/stable-x86_64-unknown-linux-gnu/bin/rustc --crate-name schema --edition=2021 examples/schema.rs --error-format=json --json=diagnostic-rendered-ansi,artifacts,future-incompat --diagnostic-width=185 --crate-type bin --emit=dep-info,link -C embed-bitcode=no -C debuginfo=2 --cfg 'feature="arrayvec"' --cfg 'feature="auto-optimize"' --cfg 'feature="auto-self-copy-optimization"' --cfg 'feature="auto-unroll-varint-encoding"' --cfg 'feature="bstr"' --cfg 'feature="bytestring"' --cfg 'feature="chrono"' --cfg 'feature="default"' --cfg 'feature="derive"' --cfg 'feature="detailed-errors"' --cfg 'feature="extended-diagnostics"' --cfg 'feature="full-test-suite"' --cfg 'feature="hashbrown"' --cfg 'feature="smallvec"' --cfg 'feature="smol_str"' --cfg 'feature="std"' --cfg 'feature="thin-vec"' --cfg 'feature="third-party-type-support"' --cfg 'feature="threadsafe-schema"' --cfg 'feature="time"' --cfg 'feature="tinyvec"' --check-cfg 'cfg(docsrs,test)' --check-cfg 'cfg(feature, values("arrayvec", "auto-optimize", "auto-self-copy-optimization", "auto-unroll-varint-encoding", "bstr", "bytestring", "chrono", "default", "derive", "detailed-errors", "extended-diagnostics", "forbid-unsafe", "full-test-suite", "hashbrown", "no-recursion-limit", "pprof", "prefer-no-self-copy-optimization", "prefer-no-unroll-varint-encoding", "self-copy-optimization", "smallvec", "smol_str", "std", "test-smolstr-force-noncontiguous", "test-suite-extra", "thin-vec", "third-party-type-support", "threadsafe-schema", "time", "tinyvec", "unroll-varint-encoding"))' -C metadata=34e72ac2315b8ee5 -C extra-filename=-8d74cb51b72d2517 --out-dir /home/widders/repos/bilrost/target/debug/examples -C incremental=/home/widders/repos/bilrost/target/debug/incremental -L dependency=/home/widders/repos/bilrost/target/debug/deps --extern arbitrary=/home/widders/repos/bilrost/target/debug/deps/libarbitrary-0728679b9e5fed63.rlib --extern arrayvec=/home/widders/repos/bilrost/target/debug/deps/libarrayvec-43fb47e4eb494826.rlib --extern bilrost=/home/widders/repos/bilrost/target/debug/deps/libbilrost-bf6a6f201ad1d6ad.rlib --extern bilrost=/home/widders/repos/bilrost/target/debug/deps/libbilrost-bf6a6f201ad1d6ad.rlib --extern bilrost_derive=/home/widders/repos/bilrost/target/debug/deps/libbilrost_derive-49c546cfd470378f.so --extern bilrost_types=/home/widders/repos/bilrost/target/debug/deps/libbilrost_types-9d0cd75059bc5925.rlib --extern bstr=/home/widders/repos/bilrost/target/debug/deps/libbstr-6c79ec6770561b68.rlib --extern bytes=/home/widders/repos/bilrost/target/debug/deps/libbytes-89660b0376fecedf.rlib --extern bytestring=/home/widders/repos/bilrost/target/debug/deps/libbytestring-d5491aa098aff8c8.rlib --extern chrono=/home/widders/repos/bilrost/target/debug/deps/libchrono-15470d385670c818.rlib --extern const_panic=/home/widders/repos/bilrost/target/debug/deps/libconst_panic-a84a675caa466021.rlib --extern criterion=/home/widders/repos/bilrost/target/debug/deps/libcriterion-95d5562a18b272eb.rlib --extern hashbrown=/home/widders/repos/bilrost/target/debug/deps/libhashbrown-5fe99400d436e3d9.rlib --extern itertools=/home/widders/repos/bilrost/target/debug/deps/libitertools-e667890de3b201ca.rlib --extern proptest=/home/widders/repos/bilrost/target/debug/deps/libproptest-ba16e32df9e695e4.rlib --extern rand=/home/widders/repos/bilrost/target/debug/deps/librand-b94da0b99e561c86.rlib --extern smallvec=/home/widders/repos/bilrost/target/debug/deps/libsmallvec-0768e0b6ef61c4d6.rlib --extern smol_str=/home/widders/repos/bilrost/target/debug/deps/libsmol_str-b563041025dd90b3.rlib --extern spin=/home/widders/repos/bilrost/target/debug/deps/libspin-9c58c3f0349ea4df.rlib --extern static_assertions=/home/widders/repos/bilrost/target/debug/deps/libstatic_assertions-b762000ac734cfdb.rlib --extern thin_vec=/home/widders/repos/bilrost/target/debug/deps/libthin_vec-fa529e225a04fbba.rlib --extern time=/home/widders/repos/bilrost/target/debug/deps/libtime-bda0b5b6beb993f2.rlib --extern tinyvec=/home/widders/repos/bilrost/target/debug/deps/libtinyvec-0590a625239ec7c9.rlib --extern yoke=/home/widders/repos/bilrost/target/debug/deps/libyoke-15ebf107e3aab358.rlib --cfg rustc_1_66 --cfg rustc_1_82 --check-cfg 'cfg(rustc_1_66)' --check-cfg 'cfg(rustc_1_82)'` (exit status: 101)

thread 'rustc' (521520) panicked at /rustc-dev/31fca3adb283cc9dfd56b49cdee9a96eb9c96ffd/compiler/rustc_middle/src/ty/instance.rs:568:21:
Box<dyn Any>
stack backtrace:
   0: std::panicking::begin_panic::<rustc_errors::ExplicitBug>
   1: <rustc_errors::diagnostic::BugAbort as rustc_errors::diagnostic::EmissionGuarantee>::emit_producing_guarantee
   2: <rustc_errors::DiagCtxtHandle>::span_bug::<rustc_span::span_encoding::Span, alloc::string::String>
   3: rustc_middle::util::bug::opt_span_bug_fmt::<rustc_span::span_encoding::Span>::{closure#0}
   4: rustc_middle::ty::context::tls::with_opt::<rustc_middle::util::bug::opt_span_bug_fmt<rustc_span::span_encoding::Span>::{closure#0}, !>::{closure#0}
   5: rustc_middle::ty::context::tls::with_context_opt::<rustc_middle::ty::context::tls::with_opt<rustc_middle::util::bug::opt_span_bug_fmt<rustc_span::span_encoding::Span>::{closure#0}, !>::{closure#0}, !>
   6: rustc_middle::util::bug::span_bug_fmt::<rustc_span::span_encoding::Span>
   7: <rustc_middle::ty::instance::Instance>::expect_resolve
   8: <rustc_monomorphize::collector::MirUsedCollector as rustc_middle::mir::visit::Visitor>::visit_terminator
   9: rustc_monomorphize::collector::items_of_instance
      [... omitted 1 frame ...]
  10: rustc_monomorphize::collector::collect_items_rec
  11: rustc_monomorphize::collector::collect_items_rec
  12: rustc_monomorphize::collector::collect_items_rec
  13: rustc_monomorphize::collector::collect_items_rec
  14: rustc_monomorphize::collector::collect_crate_mono_items::{closure#1}::{closure#0}
  15: rustc_monomorphize::partitioning::collect_and_partition_mono_items
      [... omitted 1 frame ...]
  16: rustc_codegen_ssa::base::codegen_crate::<rustc_codegen_llvm::LlvmCodegenBackend>
  17: <rustc_codegen_llvm::LlvmCodegenBackend as rustc_codegen_ssa::traits::backend::CodegenBackend>::codegen_crate
  18: <rustc_interface::queries::Linker>::codegen_and_build_linker
  19: rustc_interface::interface::run_compiler::<(), rustc_driver_impl::run_compiler::{closure#0}>::{closure#1}
note: Some details are omitted, run with `RUST_BACKTRACE=full` for a verbose backtrace.

Start with the reported failure in examples/schema.rs at 15:35 and reproduce the build using the stable, beta, or nightly compiler versions listed. The issue provides no code or minimal reproducer, so first reduce the committed branch to a verifiable example while preserving the monomorphization panic and query stack. Done means a reproducible case and a compiler fix or a clearly isolated cause.