ICE with probably recursive opaque types and closures

[Aegrithas]

Messing around with a Haskell-like implementation of fix , I encountered two presumably similar ICEs
(would think they're the same, but the error messages are obviously different). The other one is here.

I'm pretty sure this should be an error, based on the reasoning that fix returns an opaque type, so, while the output of fix might be G, it also might not (and in this case, isn't), and since f only accepts Gs, f(fix(anything)) should be an error.

Code

fn main() {
  let f = fix(|_: &dyn Fn()| {});
  f();
}

fn fix<F: Fn(G), G: Fn()>(f: F) -> impl Fn() {
  move || f(fix(&f))
}

Meta

rustc --version --verbose:

rustc 1.62.0 (a8314ef7d 2022-06-27)
binary: rustc
commit-hash: a8314ef7d0ec7b75c336af2c9857bfaf43002bfc
commit-date: 2022-06-27
host: x86_64-pc-windows-msvc
release: 1.62.0
LLVM version: 14.0.5

Same ICE on nightly:

rustc 1.64.0-nightly (7425fb293 2022-06-30)
binary: rustc
commit-hash: 7425fb293f510a6f138e82a963a3bc599a5b9e1c
commit-date: 2022-06-30
host: x86_64-pc-windows-msvc
release: 1.64.0-nightly
LLVM version: 14.0.6

Error output

error: internal compiler error: /rustc/a8314ef7d0ec7b75c336af2c9857bfaf43002bfc\compiler\rustc_codegen_ssa\src\mir\block.rs:1156:22: codegen_argument: OperandRef(Immediate((i8*:  %7 = load i8*, i8** %2, align 8, !nonnull !2, !align !3, !noundef !2)) @ TyAndLayout { ty: [closure@ICE.rs:7:3: 7:21], layout: Layout { fields: Arbitrary { offsets: [Size(0 bytes)], memory_index: [0] }, variants: Single { index: 0 }, abi: Scalar(Initialized { value: Pointer, valid_range: 1..=18446744073709551615 }), largest_niche: Some(Niche { offset: Size(0 bytes), value: Pointer, valid_range: 1..=18446744073709551615 }), align: AbiAndPrefAlign { abi: Align(8 bytes), pref: Align(8 bytes) }, size: Size(8 bytes) } }) invalid for pair argument

thread 'rustc' panicked at 'Box<dyn Any>', /rustc/a8314ef7d0ec7b75c336af2c9857bfaf43002bfc\compiler\rustc_errors\src\lib.rs:1335:9
stack backtrace:
   0:     0x7ff8a09a994f - <std::sys_common::backtrace::_print::DisplayBacktrace as core::fmt::Display>::fmt::hacdb30195c80e0b1
   1:     0x7ff8a09e484a - core::fmt::write::h933e103661a87ff3
   2:     0x7ff8a099bf79 - <std::io::IoSlice as core::fmt::Debug>::fmt::hea673ff643a18274
   3:     0x7ff8a09ad1fb - std::panicking::default_hook::h663c37f307fa2cce
   4:     0x7ff8a09acdee - std::panicking::default_hook::h663c37f307fa2cce
   5:     0x7ff861bbefb9 - <rustc_middle[fc52725189803489]::ty::SymbolName as core[eeb9ad4fed407cd7]::fmt::Debug>::fmt
   6:     0x7ff8a09adada - std::panicking::rust_panic_with_hook::ha00d018f7a00c749
   7:     0x7ff866010955 - <rustc_middle[fc52725189803489]::ty::adt::AdtKind as core[eeb9ad4fed407cd7]::fmt::Debug>::fmt
   8:     0x7ff866010689 - <rustc_middle[fc52725189803489]::ty::adt::AdtKind as core[eeb9ad4fed407cd7]::fmt::Debug>::fmt
   9:     0x7ff866640d49 - <rustc_query_impl[dc8a99b54703bf7d]::on_disk_cache::OnDiskCache>::store_side_effects_for_anon_node
  10:     0x7ff86611b369 - <rustc_middle[fc52725189803489]::ty::subst::UserSubsts as rustc_middle[fc52725189803489]::ty::context::Lift>::lift_to_tcx
  11:     0x7ff86611b153 - <rustc_middle[fc52725189803489]::ty::subst::UserSubsts as rustc_middle[fc52725189803489]::ty::context::Lift>::lift_to_tcx
  12:     0x7ff86611a872 - <rustc_middle[fc52725189803489]::ty::subst::UserSubsts as rustc_middle[fc52725189803489]::ty::context::Lift>::lift_to_tcx
  13:     0x7ff86609b159 - <rustc_middle[fc52725189803489]::ty::consts::valtree::ValTree>::zst
  14:     0x7ff86609b1dc - <rustc_middle[fc52725189803489]::ty::consts::valtree::ValTree>::zst
  15:     0x7ff8666414e8 - rustc_middle[fc52725189803489]::util::bug::bug_fmt
  16:     0x7ff861ee4804 - <rustc_codegen_llvm[a47d8e5dccee9039]::back::write::DiagnosticHandlers as core[eeb9ad4fed407cd7]::ops::drop::Drop>::drop
  17:     0x7ff861ee8678 - <rustc_codegen_llvm[a47d8e5dccee9039]::back::write::DiagnosticHandlers as core[eeb9ad4fed407cd7]::ops::drop::Drop>::drop
  18:     0x7ff861ed6e91 - <rustc_codegen_llvm[a47d8e5dccee9039]::back::write::DiagnosticHandlers as core[eeb9ad4fed407cd7]::ops::drop::Drop>::drop
  19:     0x7ff861e96942 - <rustc_codegen_llvm[a47d8e5dccee9039]::back::write::DiagnosticHandlers as core[eeb9ad4fed407cd7]::ops::drop::Drop>::drop
  20:     0x7ff861e4e1c5 - <rustc_codegen_llvm[a47d8e5dccee9039]::context::CodegenCx as rustc_codegen_ssa[c1f88a47c86a60f2]::traits::type_::LayoutTypeMethods>::reg_backend_type
  21:     0x7ff861e140b1 - <rustc_codegen_llvm[a47d8e5dccee9039]::base::ValueIter as core[eeb9ad4fed407cd7]::iter::traits::iterator::Iterator>::next
  22:     0x7ff861e90531 - <rustc_codegen_llvm[a47d8e5dccee9039]::back::write::DiagnosticHandlers as core[eeb9ad4fed407cd7]::ops::drop::Drop>::drop
  23:     0x7ff861e13a88 - <rustc_codegen_llvm[a47d8e5dccee9039]::base::ValueIter as core[eeb9ad4fed407cd7]::iter::traits::iterator::Iterator>::next
  24:     0x7ff861e95539 - <rustc_codegen_llvm[a47d8e5dccee9039]::back::write::DiagnosticHandlers as core[eeb9ad4fed407cd7]::ops::drop::Drop>::drop
  25:     0x7ff861d8fae5 - <rustc_codegen_llvm[a47d8e5dccee9039]::LlvmCodegenBackend as rustc_codegen_ssa[c1f88a47c86a60f2]::traits::backend::CodegenBackend>::codegen_crate
  26:     0x7ff861d1c072 - rustc_interface[8b243e6e96a34b94]::passes::analysis
  27:     0x7ff861cdd4f0 - <rustc_interface[8b243e6e96a34b94]::passes::LintStoreExpandImpl as rustc_expand[5fb5fc673353c3e9]::base::LintStoreExpand>::pre_expansion_lint
  28:     0x7ff861cbaee0 - <rustc_interface[8b243e6e96a34b94]::queries::Queries>::ongoing_codegen
  29:     0x7ff861b4e244 - <rustc_privacy[9daebf6d6dd1f9f8]::NamePrivacyVisitor as rustc_hir[ef6dd62a99d46082]::intravisit::Visitor>::visit_mod
  30:     0x7ff861bd19e5 - rustc_driver[87b9ba788b0782fb]::pretty::print_after_hir_lowering
  31:     0x7ff861b50a30 - <rustc_privacy[9daebf6d6dd1f9f8]::NamePrivacyVisitor as rustc_hir[ef6dd62a99d46082]::intravisit::Visitor>::visit_mod
  32:     0x7ff861b72d37 - <rustc_privacy[9daebf6d6dd1f9f8]::NamePrivacyVisitor as rustc_hir[ef6dd62a99d46082]::intravisit::Visitor>::visit_mod
  33:     0x7ff861b7cd56 - <rustc_driver[87b9ba788b0782fb]::args::Error as core[eeb9ad4fed407cd7]::fmt::Debug>::fmt
  34:     0x7ff861b7de78 - <rustc_driver[87b9ba788b0782fb]::args::Error as core[eeb9ad4fed407cd7]::fmt::Debug>::fmt
  35:     0x7ff8a09beccc - std::sys::windows::thread::Thread::new::hc027ed84984f61da
  36:     0x7ff8d65f7034 - BaseThreadInitThunk
  37:     0x7ff8d7242651 - RtlUserThreadStart

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 1.62.0 (a8314ef7d 2022-06-27) running on x86_64-pc-windows-msvc

query stack during panic:
end of query stack

Backtrace

   0:     0x7ff8a09a994f - <std::sys_common::backtrace::_print::DisplayBacktrace as core::fmt::Display>::fmt::hacdb30195c80e0b1
   1:     0x7ff8a09e484a - core::fmt::write::h933e103661a87ff3
   2:     0x7ff8a099bf79 - <std::io::IoSlice as core::fmt::Debug>::fmt::hea673ff643a18274
   3:     0x7ff8a09ad1fb - std::panicking::default_hook::h663c37f307fa2cce
   4:     0x7ff8a09acdee - std::panicking::default_hook::h663c37f307fa2cce
   5:     0x7ff861bbefb9 - <rustc_middle[fc52725189803489]::ty::SymbolName as core[eeb9ad4fed407cd7]::fmt::Debug>::fmt
   6:     0x7ff8a09adada - std::panicking::rust_panic_with_hook::ha00d018f7a00c749
   7:     0x7ff866010955 - <rustc_middle[fc52725189803489]::ty::adt::AdtKind as core[eeb9ad4fed407cd7]::fmt::Debug>::fmt
   8:     0x7ff866010689 - <rustc_middle[fc52725189803489]::ty::adt::AdtKind as core[eeb9ad4fed407cd7]::fmt::Debug>::fmt
   9:     0x7ff866640d49 - <rustc_query_impl[dc8a99b54703bf7d]::on_disk_cache::OnDiskCache>::store_side_effects_for_anon_node
  10:     0x7ff86611b369 - <rustc_middle[fc52725189803489]::ty::subst::UserSubsts as rustc_middle[fc52725189803489]::ty::context::Lift>::lift_to_tcx
  11:     0x7ff86611b153 - <rustc_middle[fc52725189803489]::ty::subst::UserSubsts as rustc_middle[fc52725189803489]::ty::context::Lift>::lift_to_tcx
  12:     0x7ff86611a872 - <rustc_middle[fc52725189803489]::ty::subst::UserSubsts as rustc_middle[fc52725189803489]::ty::context::Lift>::lift_to_tcx
  13:     0x7ff86609b159 - <rustc_middle[fc52725189803489]::ty::consts::valtree::ValTree>::zst
  14:     0x7ff86609b1dc - <rustc_middle[fc52725189803489]::ty::consts::valtree::ValTree>::zst
  15:     0x7ff8666414e8 - rustc_middle[fc52725189803489]::util::bug::bug_fmt
  16:     0x7ff861ee4804 - <rustc_codegen_llvm[a47d8e5dccee9039]::back::write::DiagnosticHandlers as core[eeb9ad4fed407cd7]::ops::drop::Drop>::drop
  17:     0x7ff861ee8678 - <rustc_codegen_llvm[a47d8e5dccee9039]::back::write::DiagnosticHandlers as core[eeb9ad4fed407cd7]::ops::drop::Drop>::drop
  18:     0x7ff861ed6e91 - <rustc_codegen_llvm[a47d8e5dccee9039]::back::write::DiagnosticHandlers as core[eeb9ad4fed407cd7]::ops::drop::Drop>::drop
  19:     0x7ff861e96942 - <rustc_codegen_llvm[a47d8e5dccee9039]::back::write::DiagnosticHandlers as core[eeb9ad4fed407cd7]::ops::drop::Drop>::drop
  20:     0x7ff861e4e1c5 - <rustc_codegen_llvm[a47d8e5dccee9039]::context::CodegenCx as rustc_codegen_ssa[c1f88a47c86a60f2]::traits::type_::LayoutTypeMethods>::reg_backend_type
  21:     0x7ff861e140b1 - <rustc_codegen_llvm[a47d8e5dccee9039]::base::ValueIter as core[eeb9ad4fed407cd7]::iter::traits::iterator::Iterator>::next
  22:     0x7ff861e90531 - <rustc_codegen_llvm[a47d8e5dccee9039]::back::write::DiagnosticHandlers as core[eeb9ad4fed407cd7]::ops::drop::Drop>::drop
  23:     0x7ff861e13a88 - <rustc_codegen_llvm[a47d8e5dccee9039]::base::ValueIter as core[eeb9ad4fed407cd7]::iter::traits::iterator::Iterator>::next
  24:     0x7ff861e95539 - <rustc_codegen_llvm[a47d8e5dccee9039]::back::write::DiagnosticHandlers as core[eeb9ad4fed407cd7]::ops::drop::Drop>::drop
  25:     0x7ff861d8fae5 - <rustc_codegen_llvm[a47d8e5dccee9039]::LlvmCodegenBackend as rustc_codegen_ssa[c1f88a47c86a60f2]::traits::backend::CodegenBackend>::codegen_crate
  26:     0x7ff861d1c072 - rustc_interface[8b243e6e96a34b94]::passes::analysis
  27:     0x7ff861cdd4f0 - <rustc_interface[8b243e6e96a34b94]::passes::LintStoreExpandImpl as rustc_expand[5fb5fc673353c3e9]::base::LintStoreExpand>::pre_expansion_lint
  28:     0x7ff861cbaee0 - <rustc_interface[8b243e6e96a34b94]::queries::Queries>::ongoing_codegen
  29:     0x7ff861b4e244 - <rustc_privacy[9daebf6d6dd1f9f8]::NamePrivacyVisitor as rustc_hir[ef6dd62a99d46082]::intravisit::Visitor>::visit_mod
  30:     0x7ff861bd19e5 - rustc_driver[87b9ba788b0782fb]::pretty::print_after_hir_lowering
  31:     0x7ff861b50a30 - <rustc_privacy[9daebf6d6dd1f9f8]::NamePrivacyVisitor as rustc_hir[ef6dd62a99d46082]::intravisit::Visitor>::visit_mod
  32:     0x7ff861b72d37 - <rustc_privacy[9daebf6d6dd1f9f8]::NamePrivacyVisitor as rustc_hir[ef6dd62a99d46082]::intravisit::Visitor>::visit_mod
  33:     0x7ff861b7cd56 - <rustc_driver[87b9ba788b0782fb]::args::Error as core[eeb9ad4fed407cd7]::fmt::Debug>::fmt
  34:     0x7ff861b7de78 - <rustc_driver[87b9ba788b0782fb]::args::Error as core[eeb9ad4fed407cd7]::fmt::Debug>::fmt
  35:     0x7ff8a09beccc - std::sys::windows::thread::Thread::new::hc027ed84984f61da
  36:     0x7ff8d65f7034 - BaseThreadInitThunk
  37:     0x7ff8d7242651 - RtlUserThreadStart

[compiler-errors]

This regressed in #94081

[Aegrithas]

Are you sure? #99073 definitely looks like it, but this one only only gets triggered by code outside the recursive function (remove the f() in main and you get #99073).

[compiler-errors]

@Aegrithas, yes, both of these are due to the same root cause. #99073 triggers differently simply because it never gets to codegen'ing a call to the returned opaque fn. The ICE here is different because the root cause sets up an ICE (a "delayed bug") that only triggers if no other ICE or error occurs, but since we ICE during codegen, that message (the one in #99073) never gets printed here.

[Aegrithas]

Okay. Should I mark these as duplicates or something, or is it fine to leave them be?

[compiler-errors]

I will close this one as a duplicate, since the repro you produced in #99073 is a bit easier to debug IMO. Thanks for reporting these two issues.