ICE: Failed to normalize: try_normalize_erasing_regions

[zjp-CN]

error: internal compiler error: compiler/rustc_middle/src/ty/normalize_erasing_regions.rs:171:13: 
Failed to normalize core::result::Result<(), Alias(Projection, AliasTy { args: [V/#1], def_id: 
DefId(0:236 ~ regex_syntax[78c2]::ast::visitor::Visitor::Err), .. })> 
in typing_env=TypingEnv { typing_mode: PostAnalysis, 
param_env: ParamEnv { caller_bounds: [] } }, maybe try to call `try_normalize_erasing_regions` instead


thread 'rustc' (3583162) panicked at compiler/rustc_middle/src/ty/normalize_erasing_regions.rs:171:13:
Box<dyn Any>
note: run with `RUST_BACKTRACE=1` environment variable to display a backtrace

error: could not compile `regex-syntax` (lib)

This is a rustc_public bug.

[zjp-CN]

Dig:

start: fn_def num::dec2flt::float::RawFloat::integer_decode
collect
info_fn
Find all instance
  Type { ty: "num::dec2flt::float::RawFloat::to_bits", span: "/home/gh-zjp-CN/.rustup/toolchains/nightly-2025-12-06-aarch64-unknown-linux-gnu/
lib/rustlib/src/rust/library/core/src/num/dec2flt/float.rs:201:20: 201:34" }
  Type { ty: "Uint(U32)", span: "/home/gh-zjp-CN/.rustup/toolchains/nightly-2025-12-06-aarch64-unknown-linux-gnu/lib/rustlib/src/rust/library/
core/src/num/dec2flt/float.rs:202:35: 202:51" }
  Type { ty: "Uint(U32)", span: "/home/gh-zjp-CN/.rustup/toolchains/nightly-2025-12-06-aarch64-unknown-linux-gnu/lib/rustlib/src/rust/library/
core/src/num/dec2flt/float.rs:202:35: 202:51" }
  Type { ty: "Bool", span: "/home/gh-zjp-CN/.rustup/toolchains/nightly-2025-12-06-aarch64-unknown-linux-gnu/lib/rustlib/src/rust/library/core/
src/num/dec2flt/float.rs:202:35: 202:51" }
  Type { ty: "Uint(U32)", span: "/home/gh-zjp-CN/.rustup/toolchains/nightly-2025-12-06-aarch64-unknown-linux-gnu/lib/rustlib/src/rust/library/
core/src/num/dec2flt/float.rs:202:35: 202:51" }
  Type { ty: "Uint(U32)", span: "/home/gh-zjp-CN/.rustup/toolchains/nightly-2025-12-06-aarch64-unknown-linux-gnu/lib/rustlib/src/rust/library/
core/src/num/dec2flt/float.rs:202:35: 202:51" }
  Type { ty: "Uint(U32)", span: "/home/gh-zjp-CN/.rustup/toolchains/nightly-2025-12-06-aarch64-unknown-linux-gnu/lib/rustlib/src/rust/library/
core/src/num/dec2flt/float.rs:202:35: 202:51" }
  Type { ty: "ops::bit::Shr::shr", span: "/home/gh-zjp-CN/.rustup/toolchains/nightly-2025-12-06-aarch64-unknown-linux-gnu/lib/rustlib/src/rust
/library/core/src/num/dec2flt/float.rs:202:27: 202:51" }
error: internal compiler error: compiler/rustc_middle/src/ty/normalize_erasing_regions.rs:171:13: Failed to normalize Alias(Projection, AliasT
y { args: [Self/#0], def_id: DefId(0:821 ~ core[28bc]::num::dec2flt::float::RawFloat::Int), .. }) in typing_env=TypingEnv { typing_mode: PostA
nalysis, param_env: ParamEnv { caller_bounds: [] } }, maybe try to call `try_normalize_erasing_regions` instead

RUST_BACKTRACE=1

[src/main.rs:19:13] fn_def.name() = "RawFloat::integer_decode"
Getting (FnDef(DefId { id: 5, name: "RawFloat::to_bits" }), GenericArgs([Type(Ty { id: 2, kind: Param(ParamTy { index: 0, name: "Self" }) })])
)
No instance for (FnDef(DefId { id: 5, name: "RawFloat::to_bits" }), GenericArgs([Type(Ty { id: 2, kind: Param(ParamTy { index: 0, name: "Self"
 }) })]))
Getting (FnDef(DefId { id: 16, name: "std::ops::Shr::shr" }), GenericArgs([Type(Ty { id: 6, kind: Alias(Projection, AliasTy { def_id: AliasDef
(DefId { id: 17, name: "RawFloat::Int" }), args: GenericArgs([Type(Ty { id: 2, kind: Param(ParamTy { index: 0, name: "Self" }) })]) }) }), Typ
e(Ty { id: 3, kind: RigidTy(Uint(U32)) })]))
error: internal compiler error: compiler/rustc_middle/src/ty/normalize_erasing_regions.rs:171:13: Failed to normalize Alias(Projection, AliasT
y { args: [Self/#0], def_id: DefId(0:14 ~ repro[d576]::RawFloat::Int), .. }) in typing_env=TypingEnv { typing_mode: PostAnalysis, param_env: P
aramEnv { caller_bounds: [] } }, maybe try to call `try_normalize_erasing_regions` instead


thread 'rustc' (3911288) panicked at compiler/rustc_middle/src/ty/normalize_erasing_regions.rs:171:13:
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_middle::util::bug::opt_span_bug_fmt::<rustc_span::span_encoding::Span>::{closure#0}
   3: rustc_middle::ty::context::tls::with_opt::<rustc_middle::util::bug::opt_span_bug_fmt<rustc_span::span_encoding::Span>::{closure#0}, !>::
{closure#0}
   4: rustc_middle::ty::context::tls::with_context_opt::<rustc_middle::ty::context::tls::with_opt<rustc_middle::util::bug::opt_span_bug_fmt<ru
stc_span::span_encoding::Span>::{closure#0}, !>::{closure#0}, !>
   5: rustc_middle::util::bug::bug_fmt
   6: <rustc_middle::ty::normalize_erasing_regions::NormalizeAfterErasingRegionsFolder as rustc_type_ir::fold::TypeFolder<rustc_middle::ty::co
ntext::TyCtxt>>::fold_ty
   7: rustc_ty_utils::instance::resolve_instance_raw
      [... omitted 1 frame ...]
   8: <rustc_middle::ty::instance::Instance>::try_resolve
   9: <try_normalize_erasing_regions::Collector>::v_instance
             at ./src/main.rs:73:23
  10: try_normalize_erasing_regions::run
             at ./src/main.rs:22:28
  11: try_normalize_erasing_regions::main::{closure#0}
             at ./src/main.rs:11:9
  12: <try_normalize_erasing_regions::main::RustcPublic<(), (), try_normalize_erasing_regions::main::{closure#0}> as rustc_driver_impl::Callba
cks>::after_analysis::{closure#0}
             at /home/gh-zjp-CN/.rustup/toolchains/nightly-2025-12-06-aarch64-unknown-linux-gnu/lib/rustlib/rustc-src/rust/compiler/rustc_publ
ic/src/rustc_internal/mod.rs:238:44
  13: rustc_public::rustc_internal::run::<<try_normalize_erasing_regions::main::RustcPublic<(), (), try_normalize_erasing_regions::main::{clos
ure#0}> as rustc_driver_impl::Callbacks>::after_analysis::{closure#0}, ()>::{closure#0}
             at /home/gh-zjp-CN/.rustup/toolchains/nightly-2025-12-06-aarch64-unknown-linux-gnu/lib/rustlib/rustc-src/rust/compiler/rustc_publ
ic/src/rustc_internal/mod.rs:79:60
  14: rustc_public::compiler_interface::run::<rustc_public::rustc_internal::run<<try_normalize_erasing_regions::main::RustcPublic<(), (), try_
normalize_erasing_regions::main::{closure#0}> as rustc_driver_impl::Callbacks>::after_analysis::{closure#0}, ()>::{closure#0}, ()>::{closure#0
}
             at /home/gh-zjp-CN/.rustup/toolchains/nightly-2025-12-06-aarch64-unknown-linux-gnu/lib/rustlib/rustc-src/rust/compiler/rustc_publ
ic/src/compiler_interface.rs:856:40
  15: <scoped_tls::ScopedKey<core::cell::Cell<*const ()>>>::set::<rustc_public::compiler_interface::run<rustc_public::rustc_internal::run<<try
_normalize_erasing_regions::main::RustcPublic<(), (), try_normalize_erasing_regions::main::{closure#0}> as rustc_driver_impl::Callbacks>::afte
r_analysis::{closure#0}, ()>::{closure#0}, ()>::{closure#0}, core::result::Result<(), rustc_public::error::Error>>
             at /rust/deps/scoped-tls-1.0.1/src/lib.rs:137:9
  16: rustc_public::compiler_interface::run::<rustc_public::rustc_internal::run<<try_normalize_erasing_regions::main::RustcPublic<(), (), try_
normalize_erasing_regions::main::{closure#0}> as rustc_driver_impl::Callbacks>::after_analysis::{closure#0}, ()>::{closure#0}, ()>
             at /home/gh-zjp-CN/.rustup/toolchains/nightly-2025-12-06-aarch64-unknown-linux-gnu/lib/rustlib/rustc-src/rust/compiler/rustc_publ
ic/src/compiler_interface.rs:856:13
  17: rustc_public::rustc_internal::run::<<try_normalize_erasing_regions::main::RustcPublic<(), (), try_normalize_erasing_regions::main::{clos
ure#0}> as rustc_driver_impl::Callbacks>::after_analysis::{closure#0}, ()>
             at /home/gh-zjp-CN/.rustup/toolchains/nightly-2025-12-06-aarch64-unknown-linux-gnu/lib/rustlib/rustc-src/rust/compiler/rustc_publ
ic/src/rustc_internal/mod.rs:79:5
  18: <try_normalize_erasing_regions::main::RustcPublic<(), (), try_normalize_erasing_regions::main::{closure#0}> as rustc_driver_impl::Callba
cks>::after_analysis
             at /home/gh-zjp-CN/.rustup/toolchains/nightly-2025-12-06-aarch64-unknown-linux-gnu/lib/rustlib/rustc-src/rust/compiler/rustc_publ
ic/src/rustc_internal/mod.rs:237:21
  19: <rustc_interface::passes::create_and_enter_global_ctxt<core::option::Option<rustc_interface::queries::Linker>, rustc_driver_impl::run_co
mpiler::{closure#0}::{closure#2}>::{closure#2} as core::ops::function::FnOnce<(&rustc_session::session::Session, rustc_middle::ty::context::Cu
rrentGcx, alloc::sync::Arc<rustc_data_structures::jobserver::Proxy>, &std::sync::once_lock::OnceLock<rustc_middle::ty::context::GlobalCtxt>, &
rustc_data_structures::sync::worker_local::WorkerLocal<rustc_middle::arena::Arena>, &rustc_data_structures::sync::worker_local::WorkerLocal<ru
stc_hir::Arena>, rustc_driver_impl::run_compiler::{closure#0}::{closure#2})>>::call_once::{shim:vtable#0}
  20: 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.

[zjp-CN]

Created a repo https://github.com/os-checker/ICE-try_normalize_erasing_regions to minimize the problem.

As a direct solution, no Instance will be created in UPG, because the suggested try_normalize_erasing_regions or try_resolve doesn't prevent ICE.