ICE: type parameter out of range -Zmir-opt-level=2 --emit=mir

[matthiaskrgr]

Code

reduced from ./src/test/ui/issues/issue-28561.rs

#[derive(Clone)]
struct Fn<A, B> {
    f02: fn(A, B)
}

fn main() {}

Meta

rustc --version --verbose:

rustc 1.49.0-nightly (0d33ab7af 2020-10-30)
binary: rustc
commit-hash: 0d33ab7af4aebe786410b4c10367eb6ddf13af0b
commit-date: 2020-10-30
host: x86_64-unknown-linux-gnu
release: 1.49.0-nightly

Error output

rustc ./src/test/ui/issues/issue-28561.rs -Zmir-opt-level=2 --emit=mir

error: internal compiler error: compiler/rustc_middle/src/ty/subst.rs:528:17: type parameter `B/#1` (B/1) out of range when substituting, substs=[fn(A, B)]

thread 'rustc' panicked at 'Box<Any>', /rustc/0d33ab7af4aebe786410b4c10367eb6ddf13af0b/compiler/rustc_errors/src/lib.rs:891:9
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 1.49.0-nightly (0d33ab7af 2020-10-30) running on x86_64-unknown-linux-gnu

note: compiler flags: -Z mir-opt-level=2

query stack during panic:
#0 [optimized_mir] optimizing MIR for `<Fn<A, B> as std::clone::Clone>::clone`
end of query stack
error: aborting due to previous error

Backtrace

error: internal compiler error: compiler/rustc_middle/src/ty/subst.rs:528:17: type parameter `B/#1` (B/1) out of range when substituting, substs=[fn(A, B)]

thread 'rustc' panicked at 'Box<Any>', /rustc/0d33ab7af4aebe786410b4c10367eb6ddf13af0b/compiler/rustc_errors/src/lib.rs:891:9
stack backtrace:
   0:     0x7f21197865f0 - std::backtrace_rs::backtrace::libunwind::trace::h448c56741b6011d3
                               at /rustc/0d33ab7af4aebe786410b4c10367eb6ddf13af0b/library/std/src/../../backtrace/src/backtrace/libunwind.rs:100:5
   1:     0x7f21197865f0 - std::backtrace_rs::backtrace::trace_unsynchronized::h881b9d30a8a89a0c
                               at /rustc/0d33ab7af4aebe786410b4c10367eb6ddf13af0b/library/std/src/../../backtrace/src/backtrace/mod.rs:66:5
   2:     0x7f21197865f0 - std::sys_common::backtrace::_print_fmt::h720a2f61f75b9f58
                               at /rustc/0d33ab7af4aebe786410b4c10367eb6ddf13af0b/library/std/src/sys_common/backtrace.rs:67:5
   3:     0x7f21197865f0 - <std::sys_common::backtrace::_print::DisplayBacktrace as core::fmt::Display>::fmt::h8d62bbfda6d5c836
                               at /rustc/0d33ab7af4aebe786410b4c10367eb6ddf13af0b/library/std/src/sys_common/backtrace.rs:46:22
   4:     0x7f21197f652c - core::fmt::write::h1857a60b204f1b6a
                               at /rustc/0d33ab7af4aebe786410b4c10367eb6ddf13af0b/library/core/src/fmt/mod.rs:1078:17
   5:     0x7f2119778252 - std::io::Write::write_fmt::h16a9fe7680ac245c
                               at /rustc/0d33ab7af4aebe786410b4c10367eb6ddf13af0b/library/std/src/io/mod.rs:1518:15
   6:     0x7f211978b5a5 - std::sys_common::backtrace::_print::h9ba51a6db618de7d
                               at /rustc/0d33ab7af4aebe786410b4c10367eb6ddf13af0b/library/std/src/sys_common/backtrace.rs:49:5
   7:     0x7f211978b5a5 - std::sys_common::backtrace::print::h5f20e41c85e91716
                               at /rustc/0d33ab7af4aebe786410b4c10367eb6ddf13af0b/library/std/src/sys_common/backtrace.rs:36:9
   8:     0x7f211978b5a5 - std::panicking::default_hook::{{closure}}::h8d48653392f3b04c
                               at /rustc/0d33ab7af4aebe786410b4c10367eb6ddf13af0b/library/std/src/panicking.rs:208:50
   9:     0x7f211978b248 - std::panicking::default_hook::hb3948d1f74b6ff4c
                               at /rustc/0d33ab7af4aebe786410b4c10367eb6ddf13af0b/library/std/src/panicking.rs:227:9
  10:     0x7f211a0554b8 - rustc_driver::report_ice::h1ddbc5609a6e1f37
  11:     0x7f211978bea6 - std::panicking::rust_panic_with_hook::h55d23fef0ad751bc
                               at /rustc/0d33ab7af4aebe786410b4c10367eb6ddf13af0b/library/std/src/panicking.rs:597:17
  12:     0x7f211cdb27fd - std::panicking::begin_panic::{{closure}}::hd947eabc42434d7e
  13:     0x7f211cdb2676 - std::sys_common::backtrace::__rust_end_short_backtrace::ha48eb0455bf6d0a2
  14:     0x7f211cdb2756 - std::panicking::begin_panic::h673793876dd52a84
  15:     0x7f211cda38c5 - rustc_errors::HandlerInner::span_bug::h96d4d1f33fe11a81
  16:     0x7f211cda46c0 - rustc_errors::Handler::span_bug::hd4174033c6f30272
  17:     0x7f211cabfa64 - rustc_middle::util::bug::opt_span_bug_fmt::{{closure}}::hb4ddd0d3902006f3
  18:     0x7f211cab956b - rustc_middle::ty::context::tls::with_opt::{{closure}}::ha7f81bc36cab3c9f
  19:     0x7f211cab8f22 - rustc_middle::ty::context::tls::with_opt::hf0c2c2aff96e53ba
  20:     0x7f211cabf969 - rustc_middle::util::bug::opt_span_bug_fmt::hc7cbb029c2646db9
  21:     0x7f211cabf923 - rustc_middle::util::bug::span_bug_fmt::h3bf186beb4ce6b92
  22:     0x7f211cab701e - <rustc_middle::ty::subst::SubstFolder as rustc_middle::ty::fold::TypeFolder>::fold_ty::h5265163b4487a38a
  23:     0x7f211cc41852 - <smallvec::SmallVec<A> as core::iter::traits::collect::Extend<<A as smallvec::Array>::Item>>::extend::h5dc0ab4942b60e5f
  24:     0x7f211cd92602 - rustc_middle::ty::structural_impls::fold_list::h6987b80cfa543859
  25:     0x7f211cbe0ee5 - rustc_middle::ty::structural_impls::<impl rustc_middle::ty::fold::TypeFoldable for &rustc_middle::ty::TyS>::super_fold_with::hcd50cd058363ef2d
  26:     0x7f211cab6e80 - <rustc_middle::ty::subst::SubstFolder as rustc_middle::ty::fold::TypeFolder>::fold_ty::h5265163b4487a38a
  27:     0x7f211cbe0e95 - rustc_middle::ty::structural_impls::<impl rustc_middle::ty::fold::TypeFoldable for &rustc_middle::ty::TyS>::super_fold_with::hcd50cd058363ef2d
  28:     0x7f211cab6e80 - <rustc_middle::ty::subst::SubstFolder as rustc_middle::ty::fold::TypeFolder>::fold_ty::h5265163b4487a38a
  29:     0x7f211b67e213 - rustc_middle::ty::fold::TypeFoldable::fold_with::hcfc0bcab5eee2a4b
  30:     0x7f211b5ea834 - rustc_middle::ty::normalize_erasing_regions::<impl rustc_middle::ty::context::TyCtxt>::subst_and_normalize_erasing_regions::h50c1d5daecb56882
  31:     0x7f211b393dff - rustc_mir::transform::inline::Inliner::run_pass::h160d0d273d881e9b
  32:     0x7f211b39281a - <rustc_mir::transform::inline::Inline as rustc_mir::transform::MirPass>::run_pass::h616a912953f0ee0e
  33:     0x7f211b84987d - rustc_mir::transform::run_passes::h211303d522a12d5d
  34:     0x7f211b84b9d3 - rustc_mir::transform::run_optimization_passes::he68a023a63197fe9
  35:     0x7f211b84bc53 - rustc_mir::transform::optimized_mir::h9877cf2dcd224775
  36:     0x7f211b322a52 - rustc_middle::ty::query::<impl rustc_query_system::query::config::QueryAccessors<rustc_middle::ty::context::TyCtxt> for rustc_middle::ty::query::queries::optimized_mir>::compute::hc1fb28a214043661
  37:     0x7f211b6bf644 - rustc_query_system::dep_graph::graph::DepGraph<K>::with_task_impl::hdcbd220a91a0fa7d
  38:     0x7f211b6cf561 - rustc_data_structures::stack::ensure_sufficient_stack::h8cd2d9586b9bff8c
  39:     0x7f211b4bcbbf - rustc_query_system::query::plumbing::get_query_impl::h426160ef8626bfd8
  40:     0x7f211b3a2597 - rustc_mir::util::pretty::write_mir_pretty::ha9d3fce2e2d6083a
  41:     0x7f211b590331 - rustc_mir::transform::dump_mir::emit_mir::he6266d14022fc931
  42:     0x7f211a2a1c54 - rustc_interface::passes::QueryContext::enter::h9b049407f643d454
  43:     0x7f211a2c1933 - rustc_interface::queries::Queries::ongoing_codegen::h90e1d78cee1f0a3b
  44:     0x7f211a0723a0 - rustc_interface::queries::<impl rustc_interface::interface::Compiler>::enter::h25b522245624a405
  45:     0x7f211a035a2f - rustc_span::with_source_map::h7455fffe3cd153a4
  46:     0x7f211a06d4f1 - scoped_tls::ScopedKey<T>::set::h8ae8151712a551fd
  47:     0x7f211a077c25 - std::sys_common::backtrace::__rust_begin_short_backtrace::h26de371bc27662fc
  48:     0x7f2119fdf648 - core::ops::function::FnOnce::call_once{{vtable.shim}}::h80d1a8eb7971174b
  49:     0x7f211979aeaa - <alloc::boxed::Box<F,A> as core::ops::function::FnOnce<Args>>::call_once::h9e7afb7a0a438236
                               at /rustc/0d33ab7af4aebe786410b4c10367eb6ddf13af0b/library/alloc/src/boxed.rs:1307:9
  50:     0x7f211979aeaa - <alloc::boxed::Box<F,A> as core::ops::function::FnOnce<Args>>::call_once::h70c646c4271337a1
                               at /rustc/0d33ab7af4aebe786410b4c10367eb6ddf13af0b/library/alloc/src/boxed.rs:1307:9
  51:     0x7f211979aeaa - std::sys::unix::thread::Thread::new::thread_start::h35d2b8d36f210d02
                               at /rustc/0d33ab7af4aebe786410b4c10367eb6ddf13af0b/library/std/src/sys/unix/thread.rs:89:17
  52:     0x7f21196963e9 - start_thread
  53:     0x7f21195b3293 - __GI___clone
  54:                0x0 - <unknown>

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 1.49.0-nightly (0d33ab7af 2020-10-30) running on x86_64-unknown-linux-gnu

note: compiler flags: -Z mir-opt-level=2

query stack during panic:
#0 [optimized_mir] optimizing MIR for `<Fn<A, B> as std::clone::Clone>::clone`
end of query stack
error: aborting due to previous error

[tmiasko]

Looks like the same inliner issue as in #78529.

[matthiaskrgr]

cargo bisect rustc says this happens since 0da6d42