Clippy ICE due to `async gen` block support

[P1n3appl3]

Fuchsia's CI has picked up an ICE in clippy (that doesn't happen in rustc when run on the same code). It appeared when rust-lang/rust#118420 landed and I've confirmed that it consistently reproduces after that commit and doesn't happen before it.

We're still working on pulling out a minimal reproducer (here's the code it fails on) and either I or @tmandry will add that as a followup once we've got it.

Meta

rustc --version --verbose:

rustc 1.76.0-nightly (f967532a4 2023-12-08)
binary: rustc
commit-hash: f967532a47eb728ada44473a5c4c2eca1a45fe30
commit-date: 2023-12-08
host: x86_64-unknown-linux-gnu
release: 1.76.0-nightly
LLVM version: 17.0.5

clippy-driver --version:

clippy 0.1.76 (f967532a47e 2023-12-08)

Error output

thread 'rustc' panicked at compiler/rustc_infer/src/infer/at.rs:453:17:
`<impl futures::Future<Output = std::result::Result<(), anyhow::Error>> as std::future::IntoFuture>` has escaping bound vars, so it cannot be wrapped in a dummy binder.

Backtrace

thread 'rustc' panicked at compiler/rustc_infer/src/infer/at.rs:453:17:
`<impl futures::Future<Output = std::result::Result<(), anyhow::Error>> as std::future::IntoFuture>` has escaping bound vars, so it cannot be wrapped in a dummy binder.
stack backtrace:
   0:     0x7efd79b8407c - std::backtrace_rs::backtrace::libunwind::trace::hf094a8cb04ffe7ab
                               at /b/s/w/ir/x/w/fuchsia-third_party-rust/library/std/src/../../backtrace/src/backtrace/libunwind.rs:104:5
   1:     0x7efd79b8407c - std::backtrace_rs::backtrace::trace_unsynchronized::h636c09fb98db1a35
                               at /b/s/w/ir/x/w/fuchsia-third_party-rust/library/std/src/../../backtrace/src/backtrace/mod.rs:66:5
   2:     0x7efd79b8407c - std::sys_common::backtrace::_print_fmt::h1eada59befc0fcfd
                               at /b/s/w/ir/x/w/fuchsia-third_party-rust/library/std/src/sys_common/backtrace.rs:68:5
   3:     0x7efd79b8407c - <std::sys_common::backtrace::_print::DisplayBacktrace as core::fmt::Display>::fmt::h4e01ec961f23fdc9
                               at /b/s/w/ir/x/w/fuchsia-third_party-rust/library/std/src/sys_common/backtrace.rs:44:22
   4:     0x7efd79bddf10 - core::fmt::rt::Argument::fmt::ha10887a36292f35e
                               at /b/s/w/ir/x/w/fuchsia-third_party-rust/library/core/src/fmt/rt.rs:142:9
   5:     0x7efd79bddf10 - core::fmt::write::hbee07cdecf385aa8
                               at /b/s/w/ir/x/w/fuchsia-third_party-rust/library/core/src/fmt/mod.rs:1120:17
   6:     0x7efd79b77b9d - std::io::Write::write_fmt::h04aec15ab1f7c8bf
                               at /b/s/w/ir/x/w/fuchsia-third_party-rust/library/std/src/io/mod.rs:1810:15
   7:     0x7efd79b83e64 - std::sys_common::backtrace::_print::hef7dadde3c7c991b
                               at /b/s/w/ir/x/w/fuchsia-third_party-rust/library/std/src/sys_common/backtrace.rs:47:5
   8:     0x7efd79b83e64 - std::sys_common::backtrace::print::hfc706a679f1cb22d
                               at /b/s/w/ir/x/w/fuchsia-third_party-rust/library/std/src/sys_common/backtrace.rs:34:9
   9:     0x7efd79b86b47 - std::panicking::default_hook::{{closure}}::h6f2fb643790d779b
  10:     0x7efd79b868af - std::panicking::default_hook::h31d54eb9a87975c1
                               at /b/s/w/ir/x/w/fuchsia-third_party-rust/library/std/src/panicking.rs:292:9
  11:     0x7efd7c9359e8 - std[8e4e87a28c8e62a9]::panicking::update_hook::<alloc[c6438ab7a80186a6]::boxed::Box<rustc_driver_impl[ba9e648a54e14925]::install_ice_hook::{closure#0}>>::{closure#0}
  12:     0x7efd79b872b0 - <alloc::boxed::Box<F,A> as core::ops::function::Fn<Args>>::call::h71209ca141e025a7
                               at /b/s/w/ir/x/w/fuchsia-third_party-rust/library/alloc/src/boxed.rs:2029:9
  13:     0x7efd79b872b0 - std::panicking::rust_panic_with_hook::h437f058ecb25b82b
                               at /b/s/w/ir/x/w/fuchsia-third_party-rust/library/std/src/panicking.rs:783:13
  14:     0x7efd79b86fde - std::panicking::begin_panic_handler::{{closure}}::ha4b5f1c9147f1986
                               at /b/s/w/ir/x/w/fuchsia-third_party-rust/library/std/src/panicking.rs:657:13
  15:     0x7efd79b84546 - std::sys_common::backtrace::__rust_end_short_backtrace::hc38ecdd5f148e9db
                               at /b/s/w/ir/x/w/fuchsia-third_party-rust/library/std/src/sys_common/backtrace.rs:171:18
  16:     0x7efd79b86d42 - rust_begin_unwind
                               at /b/s/w/ir/x/w/fuchsia-third_party-rust/library/std/src/panicking.rs:645:5
  17:     0x7efd79bda5b5 - core::panicking::panic_fmt::hfaf949eaaf4decf4
                               at /b/s/w/ir/x/w/fuchsia-third_party-rust/library/core/src/panicking.rs:72:14
  18:     0x7efd80b5cb79 - <rustc_middle[99b5bdc542dd2f83]::ty::sty::TraitRef as rustc_infer[c4a55945a2525b]::infer::at::ToTrace>::to_trace
  19:     0x7efd809e9550 - <rustc_infer[c4a55945a2525b]::infer::at::At>::eq::<rustc_middle[99b5bdc542dd2f83]::ty::sty::TraitRef>
  20:     0x7efd808295e2 - <rustc_trait_selection[f4790c9683b07384]::traits::select::SelectionContext>::match_impl
  21:     0x7efd809e2702 - <rustc_infer[c4a55945a2525b]::infer::InferCtxt>::probe::<(), <rustc_trait_selection[f4790c9683b07384]::traits::select::SelectionContext>::assemble_candidates_from_impls::{closure#0}::{closure#0}>
  22:     0x7efd8092f69e - <rustc_trait_selection[f4790c9683b07384]::traits::select::SelectionContext>::assemble_candidates_from_impls::{closure#0}
  23:     0x7efd8090df80 - <rustc_middle[99b5bdc542dd2f83]::ty::context::TyCtxt>::for_each_relevant_impl_treating_projections::<<rustc_trait_selection[f4790c9683b07384]::traits::select::SelectionContext>::assemble_candidates_from_impls::{closure#0}>
  24:     0x7efd8081b37b - <rustc_trait_selection[f4790c9683b07384]::traits::select::SelectionContext>::assemble_candidates_from_impls
  25:     0x7efd8081aea8 - <rustc_trait_selection[f4790c9683b07384]::traits::select::SelectionContext>::assemble_candidates
  26:     0x7efd80816218 - <rustc_trait_selection[f4790c9683b07384]::traits::select::SelectionContext>::in_task::<<rustc_trait_selection[f4790c9683b07384]::traits::select::SelectionContext>::candidate_from_obligation::{closure#0}::{closure#0}, core[f375a3a92198feb1]::result::Result<core[f375a3a92198feb1]::option::Option<rustc_middle[99b5bdc542dd2f83]::traits::select::SelectionCandidate>, rustc_middle[99b5bdc542dd2f83]::traits::SelectionError>>::{closure#0}
  27:     0x7efd808243fd - <rustc_trait_selection[f4790c9683b07384]::traits::select::SelectionContext>::candidate_from_obligation
  28:     0x7efd808287ba - <rustc_trait_selection[f4790c9683b07384]::traits::select::SelectionContext>::evaluate_trait_predicate_recursively::{closure#0}::{closure#1}
  29:     0x7efd8082741b - <rustc_trait_selection[f4790c9683b07384]::traits::select::SelectionContext>::evaluate_trait_predicate_recursively
  30:     0x7efd80825d6a - <rustc_trait_selection[f4790c9683b07384]::traits::select::SelectionContext>::evaluate_predicate_recursively
  31:     0x7efd809deef2 - <rustc_infer[c4a55945a2525b]::infer::InferCtxt>::probe::<core[f375a3a92198feb1]::result::Result<rustc_middle[99b5bdc542dd2f83]::traits::select::EvaluationResult, rustc_middle[99b5bdc542dd2f83]::traits::select::OverflowError>, <rustc_trait_selection[f4790c9683b07384]::traits::select::SelectionContext>::evaluation_probe<<rustc_trait_selection[f4790c9683b07384]::traits::select::SelectionContext>::evaluate_root_obligation::{closure#0}>::{closure#0}>
  32:     0x7efd80815f53 - <rustc_trait_selection[f4790c9683b07384]::traits::select::SelectionContext>::evaluate_root_obligation
  33:     0x7efd8027325b - rustc_traits[3a8bba52f79d26bd]::evaluate_obligation::evaluate_obligation
  34:     0x7efd80346743 - rustc_query_impl[d7288d3d15e9da38]::plumbing::__rust_begin_short_backtrace::<rustc_query_impl[d7288d3d15e9da38]::query_impl::evaluate_obligation::dynamic_query::{closure#2}::{closure#0}, rustc_middle[99b5bdc542dd2f83]::query::erase::Erased<[u8; 2usize]>>
  35:     0x7efd806d6651 - <rustc_query_impl[d7288d3d15e9da38]::query_impl::evaluate_obligation::dynamic_query::{closure#2} as core[f375a3a92198feb1]::ops::function::FnOnce<(rustc_middle[99b5bdc542dd2f83]::ty::context::TyCtxt, rustc_type_ir[ca6bfb6fc13bdc92]::canonical::Canonical<rustc_middle[99b5bdc542dd2f83]::ty::context::TyCtxt, rustc_middle[99b5bdc542dd2f83]::ty::ParamEnvAnd<rustc_middle[99b5bdc542dd2f83]::ty::Predicate>>)>>::call_once
  36:     0x7efd803ac60d - rustc_query_system[7ec1cb1a41ff8417]::query::plumbing::try_execute_query::<rustc_query_impl[d7288d3d15e9da38]::DynamicConfig<rustc_query_system[7ec1cb1a41ff8417]::query::caches::DefaultCache<rustc_type_ir[ca6bfb6fc13bdc92]::canonical::Canonical<rustc_middle[99b5bdc542dd2f83]::ty::context::TyCtxt, rustc_middle[99b5bdc542dd2f83]::ty::ParamEnvAnd<rustc_middle[99b5bdc542dd2f83]::ty::Predicate>>, rustc_middle[99b5bdc542dd2f83]::query::erase::Erased<[u8; 2usize]>>, false, false, false>, rustc_query_impl[d7288d3d15e9da38]::plumbing::QueryCtxt, true>
  37:     0x7efd80663cde - rustc_query_impl[d7288d3d15e9da38]::query_impl::evaluate_obligation::get_query_incr::__rust_end_short_backtrace
  38:     0x7efd809fa10d - <rustc_infer[c4a55945a2525b]::infer::InferCtxt as rustc_trait_selection[f4790c9683b07384]::traits::query::evaluate_obligation::InferCtxtExt>::evaluate_obligation
  39:     0x7efd809fa51d - <rustc_infer[c4a55945a2525b]::infer::InferCtxt as rustc_trait_selection[f4790c9683b07384]::traits::query::evaluate_obligation::InferCtxtExt>::evaluate_obligation_no_overflow
  40:     0x7efd809f9b17 - <rustc_infer[c4a55945a2525b]::infer::InferCtxt as rustc_trait_selection[f4790c9683b07384]::traits::query::evaluate_obligation::InferCtxtExt>::predicate_must_hold_modulo_regions
  41:     0x5607cad1ccbb - <core[f375a3a92198feb1]::iter::adapters::copied::Copied<core[f375a3a92198feb1]::slice::iter::Iter<rustc_middle[99b5bdc542dd2f83]::ty::Clause>> as core[f375a3a92198feb1]::iter::traits::iterator::Iterator>::try_fold::<(), core[f375a3a92198feb1]::iter::adapters::filter::filter_try_fold<rustc_middle[99b5bdc542dd2f83]::ty::Clause, (), core[f375a3a92198feb1]::ops::control_flow::ControlFlow<()>, clippy_lints[c0c4b2ad4dbda2a4]::methods::unnecessary_to_owned::can_change_type::{closure#4}, core[f375a3a92198feb1]::iter::traits::iterator::Iterator::any::check<rustc_middle[99b5bdc542dd2f83]::ty::Clause, clippy_lints[c0c4b2ad4dbda2a4]::methods::unnecessary_to_owned::can_change_type::{closure#6}>::{closure#0}>::{closure#0}, core[f375a3a92198feb1]::ops::control_flow::ControlFlow<()>>
  42:     0x5607cadcad74 - clippy_lints[c0c4b2ad4dbda2a4]::methods::unnecessary_to_owned::can_change_type
  43:     0x5607cadccace - <clippy_lints[c0c4b2ad4dbda2a4]::methods::Methods as rustc_lint[41987eacc644a84f]::passes::LateLintPass>::check_expr
  44:     0x7efd807cd993 - <rustc_lint[41987eacc644a84f]::late::LateContextAndPass<rustc_lint[41987eacc644a84f]::late::RuntimeCombinedLateLintPass>>::with_lint_attrs::<<rustc_lint[41987eacc644a84f]::late::LateContextAndPass<rustc_lint[41987eacc644a84f]::late::RuntimeCombinedLateLintPass> as rustc_hir[c72dca54a63ff1f5]::intravisit::Visitor>::visit_expr::{closure#0}::{closure#0}>
  45:     0x7efd8073e903 - rustc_hir[c72dca54a63ff1f5]::intravisit::walk_expr::<rustc_lint[41987eacc644a84f]::late::LateContextAndPass<rustc_lint[41987eacc644a84f]::late::RuntimeCombinedLateLintPass>>
  46:     0x7efd807cd9ac - <rustc_lint[41987eacc644a84f]::late::LateContextAndPass<rustc_lint[41987eacc644a84f]::late::RuntimeCombinedLateLintPass>>::with_lint_attrs::<<rustc_lint[41987eacc644a84f]::late::LateContextAndPass<rustc_lint[41987eacc644a84f]::late::RuntimeCombinedLateLintPass> as rustc_hir[c72dca54a63ff1f5]::intravisit::Visitor>::visit_expr::{closure#0}::{closure#0}>
  47:     0x7efd8073e7f3 - rustc_hir[c72dca54a63ff1f5]::intravisit::walk_expr::<rustc_lint[41987eacc644a84f]::late::LateContextAndPass<rustc_lint[41987eacc644a84f]::late::RuntimeCombinedLateLintPass>>
  48:     0x7efd807cd9ac - <rustc_lint[41987eacc644a84f]::late::LateContextAndPass<rustc_lint[41987eacc644a84f]::late::RuntimeCombinedLateLintPass>>::with_lint_attrs::<<rustc_lint[41987eacc644a84f]::late::LateContextAndPass<rustc_lint[41987eacc644a84f]::late::RuntimeCombinedLateLintPass> as rustc_hir[c72dca54a63ff1f5]::intravisit::Visitor>::visit_expr::{closure#0}::{closure#0}>
  49:     0x7efd8073e213 - rustc_hir[c72dca54a63ff1f5]::intravisit::walk_expr::<rustc_lint[41987eacc644a84f]::late::LateContextAndPass<rustc_lint[41987eacc644a84f]::late::RuntimeCombinedLateLintPass>>
  50:     0x7efd807cd9ac - <rustc_lint[41987eacc644a84f]::late::LateContextAndPass<rustc_lint[41987eacc644a84f]::late::RuntimeCombinedLateLintPass>>::with_lint_attrs::<<rustc_lint[41987eacc644a84f]::late::LateContextAndPass<rustc_lint[41987eacc644a84f]::late::RuntimeCombinedLateLintPass> as rustc_hir[c72dca54a63ff1f5]::intravisit::Visitor>::visit_expr::{closure#0}::{closure#0}>
  51:     0x7efd8073e7f3 - rustc_hir[c72dca54a63ff1f5]::intravisit::walk_expr::<rustc_lint[41987eacc644a84f]::late::LateContextAndPass<rustc_lint[41987eacc644a84f]::late::RuntimeCombinedLateLintPass>>
  52:     0x7efd807cd9ac - <rustc_lint[41987eacc644a84f]::late::LateContextAndPass<rustc_lint[41987eacc644a84f]::late::RuntimeCombinedLateLintPass>>::with_lint_attrs::<<rustc_lint[41987eacc644a84f]::late::LateContextAndPass<rustc_lint[41987eacc644a84f]::late::RuntimeCombinedLateLintPass> as rustc_hir[c72dca54a63ff1f5]::intravisit::Visitor>::visit_expr::{closure#0}::{closure#0}>
  53:     0x7efd8073e213 - rustc_hir[c72dca54a63ff1f5]::intravisit::walk_expr::<rustc_lint[41987eacc644a84f]::late::LateContextAndPass<rustc_lint[41987eacc644a84f]::late::RuntimeCombinedLateLintPass>>
  54:     0x7efd807cd9ac - <rustc_lint[41987eacc644a84f]::late::LateContextAndPass<rustc_lint[41987eacc644a84f]::late::RuntimeCombinedLateLintPass>>::with_lint_attrs::<<rustc_lint[41987eacc644a84f]::late::LateContextAndPass<rustc_lint[41987eacc644a84f]::late::RuntimeCombinedLateLintPass> as rustc_hir[c72dca54a63ff1f5]::intravisit::Visitor>::visit_expr::{closure#0}::{closure#0}>
  55:     0x7efd807ce656 - <rustc_lint[41987eacc644a84f]::late::LateContextAndPass<rustc_lint[41987eacc644a84f]::late::RuntimeCombinedLateLintPass> as rustc_hir[c72dca54a63ff1f5]::intravisit::Visitor>::visit_stmt
  56:     0x7efd8072ccdc - rustc_hir[c72dca54a63ff1f5]::intravisit::walk_block::<rustc_lint[41987eacc644a84f]::late::LateContextAndPass<rustc_lint[41987eacc644a84f]::late::RuntimeCombinedLateLintPass>>
  57:     0x7efd8073e386 - rustc_hir[c72dca54a63ff1f5]::intravisit::walk_expr::<rustc_lint[41987eacc644a84f]::late::LateContextAndPass<rustc_lint[41987eacc644a84f]::late::RuntimeCombinedLateLintPass>>
  58:     0x7efd807cd9ac - <rustc_lint[41987eacc644a84f]::late::LateContextAndPass<rustc_lint[41987eacc644a84f]::late::RuntimeCombinedLateLintPass>>::with_lint_attrs::<<rustc_lint[41987eacc644a84f]::late::LateContextAndPass<rustc_lint[41987eacc644a84f]::late::RuntimeCombinedLateLintPass> as rustc_hir[c72dca54a63ff1f5]::intravisit::Visitor>::visit_expr::{closure#0}::{closure#0}>
  59:     0x7efd8073e68f - rustc_hir[c72dca54a63ff1f5]::intravisit::walk_expr::<rustc_lint[41987eacc644a84f]::late::LateContextAndPass<rustc_lint[41987eacc644a84f]::late::RuntimeCombinedLateLintPass>>
  60:     0x7efd807cd9ac - <rustc_lint[41987eacc644a84f]::late::LateContextAndPass<rustc_lint[41987eacc644a84f]::late::RuntimeCombinedLateLintPass>>::with_lint_attrs::<<rustc_lint[41987eacc644a84f]::late::LateContextAndPass<rustc_lint[41987eacc644a84f]::late::RuntimeCombinedLateLintPass> as rustc_hir[c72dca54a63ff1f5]::intravisit::Visitor>::visit_expr::{closure#0}::{closure#0}>
  61:     0x7efd8072cd1b - rustc_hir[c72dca54a63ff1f5]::intravisit::walk_block::<rustc_lint[41987eacc644a84f]::late::LateContextAndPass<rustc_lint[41987eacc644a84f]::late::RuntimeCombinedLateLintPass>>
  62:     0x7efd8073e386 - rustc_hir[c72dca54a63ff1f5]::intravisit::walk_expr::<rustc_lint[41987eacc644a84f]::late::LateContextAndPass<rustc_lint[41987eacc644a84f]::late::RuntimeCombinedLateLintPass>>
  63:     0x7efd807cd9ac - <rustc_lint[41987eacc644a84f]::late::LateContextAndPass<rustc_lint[41987eacc644a84f]::late::RuntimeCombinedLateLintPass>>::with_lint_attrs::<<rustc_lint[41987eacc644a84f]::late::LateContextAndPass<rustc_lint[41987eacc644a84f]::late::RuntimeCombinedLateLintPass> as rustc_hir[c72dca54a63ff1f5]::intravisit::Visitor>::visit_expr::{closure#0}::{closure#0}>
  64:     0x7efd8073db86 - rustc_hir[c72dca54a63ff1f5]::intravisit::walk_body::<rustc_lint[41987eacc644a84f]::late::LateContextAndPass<rustc_lint[41987eacc644a84f]::late::RuntimeCombinedLateLintPass>>
  65:     0x7efd807cdb95 - <rustc_lint[41987eacc644a84f]::late::LateContextAndPass<rustc_lint[41987eacc644a84f]::late::RuntimeCombinedLateLintPass> as rustc_hir[c72dca54a63ff1f5]::intravisit::Visitor>::visit_nested_body
  66:     0x7efd8073e325 - rustc_hir[c72dca54a63ff1f5]::intravisit::walk_expr::<rustc_lint[41987eacc644a84f]::late::LateContextAndPass<rustc_lint[41987eacc644a84f]::late::RuntimeCombinedLateLintPass>>
  67:     0x7efd807cd9ac - <rustc_lint[41987eacc644a84f]::late::LateContextAndPass<rustc_lint[41987eacc644a84f]::late::RuntimeCombinedLateLintPass>>::with_lint_attrs::<<rustc_lint[41987eacc644a84f]::late::LateContextAndPass<rustc_lint[41987eacc644a84f]::late::RuntimeCombinedLateLintPass> as rustc_hir[c72dca54a63ff1f5]::intravisit::Visitor>::visit_expr::{closure#0}::{closure#0}>
  68:     0x7efd8073db86 - rustc_hir[c72dca54a63ff1f5]::intravisit::walk_body::<rustc_lint[41987eacc644a84f]::late::LateContextAndPass<rustc_lint[41987eacc644a84f]::late::RuntimeCombinedLateLintPass>>
  69:     0x7efd807cdb95 - <rustc_lint[41987eacc644a84f]::late::LateContextAndPass<rustc_lint[41987eacc644a84f]::late::RuntimeCombinedLateLintPass> as rustc_hir[c72dca54a63ff1f5]::intravisit::Visitor>::visit_nested_body
  70:     0x7efd80740579 - rustc_hir[c72dca54a63ff1f5]::intravisit::walk_item::<rustc_lint[41987eacc644a84f]::late::LateContextAndPass<rustc_lint[41987eacc644a84f]::late::RuntimeCombinedLateLintPass>>
  71:     0x7efd807c8e16 - <rustc_lint[41987eacc644a84f]::late::LateContextAndPass<rustc_lint[41987eacc644a84f]::late::RuntimeCombinedLateLintPass> as rustc_hir[c72dca54a63ff1f5]::intravisit::Visitor>::visit_nested_item
  72:     0x7efd8072ccdc - rustc_hir[c72dca54a63ff1f5]::intravisit::walk_block::<rustc_lint[41987eacc644a84f]::late::LateContextAndPass<rustc_lint[41987eacc644a84f]::late::RuntimeCombinedLateLintPass>>
  73:     0x7efd8073e386 - rustc_hir[c72dca54a63ff1f5]::intravisit::walk_expr::<rustc_lint[41987eacc644a84f]::late::LateContextAndPass<rustc_lint[41987eacc644a84f]::late::RuntimeCombinedLateLintPass>>
  74:     0x7efd807cd9ac - <rustc_lint[41987eacc644a84f]::late::LateContextAndPass<rustc_lint[41987eacc644a84f]::late::RuntimeCombinedLateLintPass>>::with_lint_attrs::<<rustc_lint[41987eacc644a84f]::late::LateContextAndPass<rustc_lint[41987eacc644a84f]::late::RuntimeCombinedLateLintPass> as rustc_hir[c72dca54a63ff1f5]::intravisit::Visitor>::visit_expr::{closure#0}::{closure#0}>
  75:     0x7efd8073db86 - rustc_hir[c72dca54a63ff1f5]::intravisit::walk_body::<rustc_lint[41987eacc644a84f]::late::LateContextAndPass<rustc_lint[41987eacc644a84f]::late::RuntimeCombinedLateLintPass>>
  76:     0x7efd807cdb95 - <rustc_lint[41987eacc644a84f]::late::LateContextAndPass<rustc_lint[41987eacc644a84f]::late::RuntimeCombinedLateLintPass> as rustc_hir[c72dca54a63ff1f5]::intravisit::Visitor>::visit_nested_body
  77:     0x7efd80740579 - rustc_hir[c72dca54a63ff1f5]::intravisit::walk_item::<rustc_lint[41987eacc644a84f]::late::LateContextAndPass<rustc_lint[41987eacc644a84f]::late::RuntimeCombinedLateLintPass>>
  78:     0x7efd807c8e16 - <rustc_lint[41987eacc644a84f]::late::LateContextAndPass<rustc_lint[41987eacc644a84f]::late::RuntimeCombinedLateLintPass> as rustc_hir[c72dca54a63ff1f5]::intravisit::Visitor>::visit_nested_item
  79:     0x7efd8074060c - rustc_hir[c72dca54a63ff1f5]::intravisit::walk_item::<rustc_lint[41987eacc644a84f]::late::LateContextAndPass<rustc_lint[41987eacc644a84f]::late::RuntimeCombinedLateLintPass>>
  80:     0x7efd807c8e16 - <rustc_lint[41987eacc644a84f]::late::LateContextAndPass<rustc_lint[41987eacc644a84f]::late::RuntimeCombinedLateLintPass> as rustc_hir[c72dca54a63ff1f5]::intravisit::Visitor>::visit_nested_item
  81:     0x7efd8074060c - rustc_hir[c72dca54a63ff1f5]::intravisit::walk_item::<rustc_lint[41987eacc644a84f]::late::LateContextAndPass<rustc_lint[41987eacc644a84f]::late::RuntimeCombinedLateLintPass>>
  82:     0x7efd807c8e16 - <rustc_lint[41987eacc644a84f]::late::LateContextAndPass<rustc_lint[41987eacc644a84f]::late::RuntimeCombinedLateLintPass> as rustc_hir[c72dca54a63ff1f5]::intravisit::Visitor>::visit_nested_item
  83:     0x7efd807d110c - rustc_lint[41987eacc644a84f]::late::check_crate::{closure#0}
  84:     0x7efd80798629 - rustc_data_structures[1627bcfcb21e4def]::sync::parallel::disabled::join::<rustc_lint[41987eacc644a84f]::late::check_crate::{closure#0}, rustc_lint[41987eacc644a84f]::late::check_crate::{closure#1}, (), ()>
  85:     0x7efd807d0caa - rustc_lint[41987eacc644a84f]::late::check_crate
  86:     0x7efd7caefc6d - std[8e4e87a28c8e62a9]::panicking::try::<(), core[f375a3a92198feb1]::panic::unwind_safe::AssertUnwindSafe<rustc_interface[775976246e434a93]::passes::analysis::{closure#6}::{closure#1}::{closure#0}::{closure#0}::{closure#2}>>
  87:     0x7efd7caa98b9 - <rustc_data_structures[1627bcfcb21e4def]::sync::parallel::ParallelGuard>::run::<(), rustc_interface[775976246e434a93]::passes::analysis::{closure#6}::{closure#1}::{closure#0}::{closure#0}::{closure#2}>
  88:     0x7efd7caf13b3 - std[8e4e87a28c8e62a9]::panicking::try::<(), core[f375a3a92198feb1]::panic::unwind_safe::AssertUnwindSafe<rustc_interface[775976246e434a93]::passes::analysis::{closure#6}::{closure#1}::{closure#0}>>
  89:     0x7efd7caa6786 - <rustc_session[fc9c4eccb5e976b]::session::Session>::time::<(), rustc_interface[775976246e434a93]::passes::analysis::{closure#6}>
  90:     0x7efd7cb20328 - rustc_interface[775976246e434a93]::passes::analysis
  91:     0x7efd80348dfa - rustc_query_impl[d7288d3d15e9da38]::plumbing::__rust_begin_short_backtrace::<rustc_query_impl[d7288d3d15e9da38]::query_impl::analysis::dynamic_query::{closure#2}::{closure#0}, rustc_middle[99b5bdc542dd2f83]::query::erase::Erased<[u8; 1usize]>>
  92:     0x7efd80564688 - <rustc_query_impl[d7288d3d15e9da38]::query_impl::analysis::dynamic_query::{closure#2} as core[f375a3a92198feb1]::ops::function::FnOnce<(rustc_middle[99b5bdc542dd2f83]::ty::context::TyCtxt, ())>>::call_once
  93:     0x7efd80382c04 - rustc_query_system[7ec1cb1a41ff8417]::query::plumbing::try_execute_query::<rustc_query_impl[d7288d3d15e9da38]::DynamicConfig<rustc_query_system[7ec1cb1a41ff8417]::query::caches::SingleCache<rustc_middle[99b5bdc542dd2f83]::query::erase::Erased<[u8; 1usize]>>, false, false, false>, rustc_query_impl[d7288d3d15e9da38]::plumbing::QueryCtxt, true>
  94:     0x7efd80529f6b - rustc_query_impl[d7288d3d15e9da38]::query_impl::analysis::get_query_incr::__rust_end_short_backtrace
  95:     0x7efd7c8da2eb - <rustc_middle[99b5bdc542dd2f83]::ty::context::GlobalCtxt>::enter::<rustc_driver_impl[ba9e648a54e14925]::run_compiler::{closure#0}::{closure#0}::{closure#3}, core[f375a3a92198feb1]::result::Result<(), rustc_span[30e96fe221b2db3f]::ErrorGuaranteed>>
  96:     0x7efd7c8f1b9c - <rustc_interface[775976246e434a93]::interface::Compiler>::enter::<rustc_driver_impl[ba9e648a54e14925]::run_compiler::{closure#0}::{closure#0}, core[f375a3a92198feb1]::result::Result<core[f375a3a92198feb1]::option::Option<rustc_interface[775976246e434a93]::queries::Linker>, rustc_span[30e96fe221b2db3f]::ErrorGuaranteed>>
  97:     0x7efd7c93b537 - rustc_span[30e96fe221b2db3f]::set_source_map::<core[f375a3a92198feb1]::result::Result<(), rustc_span[30e96fe221b2db3f]::ErrorGuaranteed>, rustc_interface[775976246e434a93]::interface::run_compiler<core[f375a3a92198feb1]::result::Result<(), rustc_span[30e96fe221b2db3f]::ErrorGuaranteed>, rustc_driver_impl[ba9e648a54e14925]::run_compiler::{closure#0}>::{closure#0}::{closure#0}>
  98:     0x7efd7c968555 - <scoped_tls[aae13a65dedca084]::ScopedKey<rustc_span[30e96fe221b2db3f]::SessionGlobals>>::set::<rustc_interface[775976246e434a93]::util::run_in_thread_pool_with_globals<rustc_interface[775976246e434a93]::interface::run_compiler<core[f375a3a92198feb1]::result::Result<(), rustc_span[30e96fe221b2db3f]::ErrorGuaranteed>, rustc_driver_impl[ba9e648a54e14925]::run_compiler::{closure#0}>::{closure#0}, core[f375a3a92198feb1]::result::Result<(), rustc_span[30e96fe221b2db3f]::ErrorGuaranteed>>::{closure#0}, core[f375a3a92198feb1]::result::Result<(), rustc_span[30e96fe221b2db3f]::ErrorGuaranteed>>
  99:     0x7efd7c93ba21 - rustc_span[30e96fe221b2db3f]::create_session_globals_then::<core[f375a3a92198feb1]::result::Result<(), rustc_span[30e96fe221b2db3f]::ErrorGuaranteed>, rustc_interface[775976246e434a93]::util::run_in_thread_pool_with_globals<rustc_interface[775976246e434a93]::interface::run_compiler<core[f375a3a92198feb1]::result::Result<(), rustc_span[30e96fe221b2db3f]::ErrorGuaranteed>, rustc_driver_impl[ba9e648a54e14925]::run_compiler::{closure#0}>::{closure#0}, core[f375a3a92198feb1]::result::Result<(), rustc_span[30e96fe221b2db3f]::ErrorGuaranteed>>::{closure#0}>
 100:     0x7efd7c96fe30 - std[8e4e87a28c8e62a9]::sys_common::backtrace::__rust_begin_short_backtrace::<rustc_interface[775976246e434a93]::util::run_in_thread_with_globals<rustc_interface[775976246e434a93]::util::run_in_thread_pool_with_globals<rustc_interface[775976246e434a93]::interface::run_compiler<core[f375a3a92198feb1]::result::Result<(), rustc_span[30e96fe221b2db3f]::ErrorGuaranteed>, rustc_driver_impl[ba9e648a54e14925]::run_compiler::{closure#0}>::{closure#0}, core[f375a3a92198feb1]::result::Result<(), rustc_span[30e96fe221b2db3f]::ErrorGuaranteed>>::{closure#0}, core[f375a3a92198feb1]::result::Result<(), rustc_span[30e96fe221b2db3f]::ErrorGuaranteed>>::{closure#0}::{closure#0}, core[f375a3a92198feb1]::result::Result<(), rustc_span[30e96fe221b2db3f]::ErrorGuaranteed>>
 101:     0x7efd7c972641 - <<std[8e4e87a28c8e62a9]::thread::Builder>::spawn_unchecked_<rustc_interface[775976246e434a93]::util::run_in_thread_with_globals<rustc_interface[775976246e434a93]::util::run_in_thread_pool_with_globals<rustc_interface[775976246e434a93]::interface::run_compiler<core[f375a3a92198feb1]::result::Result<(), rustc_span[30e96fe221b2db3f]::ErrorGuaranteed>, rustc_driver_impl[ba9e648a54e14925]::run_compiler::{closure#0}>::{closure#0}, core[f375a3a92198feb1]::result::Result<(), rustc_span[30e96fe221b2db3f]::ErrorGuaranteed>>::{closure#0}, core[f375a3a92198feb1]::result::Result<(), rustc_span[30e96fe221b2db3f]::ErrorGuaranteed>>::{closure#0}::{closure#0}, core[f375a3a92198feb1]::result::Result<(), rustc_span[30e96fe221b2db3f]::ErrorGuaranteed>>::{closure#1} as core[f375a3a92198feb1]::ops::function::FnOnce<()>>::call_once::{shim:vtable#0}
 102:     0x7efd79b91265 - <alloc::boxed::Box<F,A> as core::ops::function::FnOnce<Args>>::call_once::h1e97f54b7cd855fa
                               at /b/s/w/ir/x/w/fuchsia-third_party-rust/library/alloc/src/boxed.rs:2015:9
 103:     0x7efd79b91265 - <alloc::boxed::Box<F,A> as core::ops::function::FnOnce<Args>>::call_once::h6131a2913c812b64
                               at /b/s/w/ir/x/w/fuchsia-third_party-rust/library/alloc/src/boxed.rs:2015:9
 104:     0x7efd79b91265 - std::sys::unix::thread::Thread::new::thread_start::he0eff1607c6cd732
                               at /b/s/w/ir/x/w/fuchsia-third_party-rust/library/std/src/sys/unix/thread.rs:108:17
 105:     0x7efd798983ec - start_thread
                               at ./nptl/pthread_create.c:444:8
 106:     0x7efd79918a4c - __GI___clone3
                               at ./misc/../sysdeps/unix/sysv/linux/x86_64/clone3.S:81

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

note: we would appreciate a bug report: https://github.com/rust-lang/rust-clippy/issues/new?template=ice.yml

note: please attach the file at `/mnt/fuchsia/out/default/rustc-ice-2023-12-15T19_17_16-1821745.txt` to your bug report

note: compiler flags: --crate-type bin -C linker=../../prebuilt/third_party/clang/linux-x64/bin/clang++ -C default-linker-libraries -C link-arg=--sysroot=../../prebuilt/third_party/sysroot/linux -C link-arg=--target=x86_64-unknown-linux-gnu -C link-arg=-stdlib=libc++ -C link-arg=--start-no-unused-arguments -C link-arg=-unwindlib=libunwind -C link-arg=-rtlib=compiler-rt -C link-arg=--end-no-unused-arguments -C link-arg=-fuse-ld=lld -C link-arg=-Wl,--build-id -Z remap-cwd-prefix=. -C opt-level=0 -C debuginfo=2 -C link-arg=-gz=zstd -C incremental=[REDACTED] -Z allow-features= -C debug-assertions=yes -C linker=../../prebuilt/third_party/clang/linux-x64/bin/clang++ -C default-linker-libraries -C link-arg=--sysroot=../../prebuilt/third_party/sysroot/linux -C link-arg=--target=x86_64-unknown-linux-gnu -C link-arg=-stdlib=libc++ -C link-arg=--start-no-unused-arguments -C link-arg=-unwindlib=libunwind -C link-arg=-rtlib=compiler-rt -C link-arg=--end-no-unused-arguments -C link-arg=-fuse-ld=lld -C link-arg=-Wl,--build-id -C link-arg=-fPIE -C link-arg=-pie -C link-arg=-static-libstdc++ -C link-arg=-Wl,-rpath=$ORIGIN/ -Z no_codegen

query stack during panic:
#0 [evaluate_obligation] evaluating trait selection obligation `fuzzer::<impl at ../../src/developer/ffx/plugins/fuzz/src/fuzzer.rs:27:1: 27:30>::add::{opaque#0}: core::future::into_future::IntoFuture`
rust-lang/rust#1 [analysis] running analysis passes on this crate
end of query stack

[Jarcho]

Same as #11952. Fixed in #11953.

[compiler-errors]

What does this have to do with async gen? The ICE has to do with normal futures.

[Jarcho]

That PR changed either how async fn was lowered or how await was lowered which. The new lowering ended up trigger a bug in clippy.

[compiler-errors]

@Jarcho: That PR should not have affected how async fn or await is lowered, especially not affecting the way that we do trait selection or normalization for those types.

@P1n3appl3: Are you certain that this is failing after rust-lang/rust@f967532, and not some other merge commit on that same day? If you are certain, could you please instruct me how to reproduce the ICE? I have no idea how to build fuchsia.

[Jarcho]

Some PR around that time made a change, but I never verified which commit did. #11952 has a repro using async fn.

---

The clippy bug takes quite a bit to trigger and small changes can avoid it. Minimal repro without async would be this:

fn f<'a, T: AsRef<[u8]>>(x: T, y: &'a ()) -> impl 'a + FnOnce() {
    move || {
        let _y = y;
    }
}

fn g(_: impl FnOnce()) {}

fn main() {
    g(f([].to_vec(), &()));
}

Cause was clippy taking the return type of f (without the signature's binder) and checking if it meets the predicates required by g. Also note that f must be used immediately by g, otherwise it's never checked. e.g. the following didn't trigger the ICE:

let x = f([].to_vec(), &());
g(x);

[compiler-errors]

This is the change from rust-lang/rust#118420 that causes clippy to begin ICEing:

https://github.com/rust-lang/rust/pull/118420/files#r1419874371

That line fixes a bug where we were not recording the node_args properly during writeback in HIR typeck, and that bug was silently causing some code to not be executed in clippy due to a defensively placed if-condition:

rust-clippy/clippy_lints/src/methods/unnecessary_to_owned.rs

Lines 451 to 452 in ac4c209

	// https://github.com/rust-lang/rust-clippy/issues/9504 and https://github.com/rust-lang/rust-clippy/issues/10021
	&& (param_index as usize) < call_generic_args.len()

But now that the args were recorded correctly, that if-condition no longer evaluated to false, which means we actually attempt to normalize the types here.

I want to make it very clear that that change I made to HIR typeck is not wrong, and that it only causes clippy to start exercising code that it was previously silently skipping.

[Jarcho]

I had assumed it was lowering changes that caused it since Clippy can be pretty sensitive to the exact HIR generated (I only took a quick look at that PR since I had already found the bug by that point). Either way it definitely exposed a Clippy bug in more code than it originally showed up in.

[compiler-errors]

I'm mostly just confused why even though the root cause for #9504 was correctly identified in #9505 ("Compiler generated call into_future nodes return empty substs"), it wasn't fixed in rust-lang/rust and it was instead just silently mitigated by an if statement (and later in #10027).

Had it been fixed correctly (i.e. by adding this write_args call), then the bug that #11953 fixes (incorrect handling of a binder's lifetimes) would have been surfaced much sooner.

Anyways, I don't think anything here needs to be done -- everything seems to be resolved. Thanks @Jarcho for fixing the binder ICE, and I'm glad to see that rust-lang/rust#118420 didn't introduce a real bug.