ICE: const_generics: unexpected const parent in type_of_def_id()

[Boscop]

Code

#[ext(pub, name = CollectArr)] // https://crates.io/crates/extend
impl<T: Iterator> T {
	fn collect_arr<const N: usize>(self) -> [T::Item; N]
	where
		[T::Item; N]: Array<Item = T::Item>,
		ArrayVec<[T::Item; N]>: Debug,
	{
		self.collect::<ArrayVec<[T::Item; N]>>().into_inner().expect("collect_arr")
	}
}

pub struct ChannelUsage(pub u16);

impl ChannelUsage {
	fn to_arr(&self) -> [bool; 16] {
		// self.iter().collect_arr() // works
		// self.iter().collect_arr::<16>() // error: cannot infer type for type `{integer}`
		self.iter().collect_arr::<16usize>() // ICE
	}
}

Meta

rustc --version --verbose:

rustc 1.46.0-nightly (ff5b446d2 2020-06-23)
binary: rustc
commit-hash: ff5b446d2fdbd898bc97a751f2f72858de185cf1
commit-date: 2020-06-23
host: x86_64-pc-windows-msvc
release: 1.46.0-nightly
LLVM version: 10.0

Error output

error: proj\src\lib.rs:1: unexpected const parent in type_of_def_id(): Expr(Expr { hir_id: HirId { owner: DefId(0:27 ~ vmidi[fa26]::chan_usage[0]::{{impl}}[1]::to_arr[0]), local_id: 10 }, kind: MethodCall(PathSegment { ident: collect_arr#0, hir_id: Some(HirId { owner: DefId(0:27 ~ vmidi[fa26]::chan_usage[0]::{{impl}}[1]::to_arr[0]), local_id: 5 }), res: Some(Err), args: Some(GenericArgs { args: [Const(ConstArg { value: AnonConst { hir_id: HirId { owner: DefId(0:27 ~ vmidi[fa26]::chan_usage[0]::{{impl}}[1]::to_arr[0]), local_id: 3 }, body: BodyId { hir_id: HirId { owner: DefId(0:27 ~ vmidi[fa26]::chan_usage[0]::{{impl}}[1]::to_arr[0]), local_id: 4 } } }, span: proj\src\chan_usage.rs:146:29: 146:36 (#0) })], bindings: [], parenthesized: false }), infer_args: false }, proj\src\chan_usage.rs:146:15: 146:26 (#0), [Expr { hir_id: HirId { owner: DefId(0:27 ~ vmidi[fa26]::chan_usage[0]::{{impl}}[1]::to_arr[0]), local_id: 9 }, kind: MethodCall(PathSegment { ident: iter#0, hir_id: Some(HirId { owner: DefId(0:27 ~ vmidi[fa26]::chan_usage[0]::{{impl}}[1]::to_arr[0]), local_id: 6 }), res: Some(Err), args: None, infer_args: true }, proj\src\chan_usage.rs:146:8: 146:12 (#0), [Expr { hir_id: HirId { owner: DefId(0:27 ~ vmidi[fa26]::chan_usage[0]::{{impl}}[1]::to_arr[0]), local_id: 8 }, kind: Path(Resolved(None, Path { span: proj\src\chan_usage.rs:146:3: 146:7 (#0), res: Local(HirId { owner: DefId(0:27 ~ vmidi[fa26]::chan_usage[0]::{{impl}}[1]::to_arr[0]), local_id: 1 }), segments: [PathSegment { ident: self#0, hir_id: Some(HirId { owner: DefId(0:27 ~ vmidi[fa26]::chan_usage[0]::{{impl}}[1]::to_arr[0]), local_id: 7 }), res: Some(Local(HirId { owner: DefId(0:27 ~ vmidi[fa26]::chan_usage[0]::{{impl}}[1]::to_arr[0]), local_id: 1 })), args: None, infer_args: true }] })), attrs: ThinVec(None), span: proj\src\chan_usage.rs:146:3: 146:7 (#0) }], proj\src\chan_usage.rs:146:8: 146:14 (#0)), attrs: ThinVec(None), span: proj\src\chan_usage.rs:146:3: 146:14 (#0) }], proj\src\chan_usage.rs:146:15: 146:39 (#0)), attrs: ThinVec(None), span: proj\src\chan_usage.rs:146:3: 146:39 (#0) })
note: proj\src\lib.rs:1: delayed at /rustc/ff5b446d2fdbd898bc97a751f2f72858de185cf1\src\librustc_session\session.rs:436:27
error: proj\src\chan_usage.rs:146: Const::from_anon_const: couldn't lit_to_const
note: proj\src\chan_usage.rs:146: delayed at /rustc/ff5b446d2fdbd898bc97a751f2f72858de185cf1\src\librustc_session\session.rs:436:27
error: proj\src\lib.rs:1: TyKind::Error constructed but no error reported
note: proj\src\lib.rs:1: delayed at /rustc/ff5b446d2fdbd898bc97a751f2f72858de185cf1\src\librustc_session\session.rs:436:27
error: proj\src\lib.rs:1: ty::ConstKind::Error constructed but no error reported.
note: proj\src\lib.rs:1: delayed at /rustc/ff5b446d2fdbd898bc97a751f2f72858de185cf1\src\librustc_session\session.rs:436:27
error: proj\src\chan_usage.rs:146: `ErrorReported` without an error
note: proj\src\chan_usage.rs:146: delayed at /rustc/ff5b446d2fdbd898bc97a751f2f72858de185cf1\src\librustc_session\session.rs:436:27
error: proj\src\chan_usage.rs:145: cat_expr Errd
note: proj\src\chan_usage.rs:145: delayed at /rustc/ff5b446d2fdbd898bc97a751f2f72858de185cf1\src\librustc_session\session.rs:436:27
error: proj\src\chan_usage.rs:146: cat_expr Errd
note: proj\src\chan_usage.rs:146: delayed at /rustc/ff5b446d2fdbd898bc97a751f2f72858de185cf1\src\librustc_session\session.rs:436:27
error: proj\src\chan_usage.rs:145: PromoteTemps: MIR had errors
note: proj\src\chan_usage.rs:145: delayed at /rustc/ff5b446d2fdbd898bc97a751f2f72858de185cf1\src\librustc_session\session.rs:436:27
error: proj\src\chan_usage.rs:145: broken MIR in DefId(0:27 ~ vmidi[fa26]::chan_usage[0]::{{impl}}[1]::to_arr[0]) ("return type"): bad type [type error]
note: proj\src\chan_usage.rs:145: delayed at src\librustc_mir\borrow_check\type_check\mod.rs:258:27
error: proj\src\chan_usage.rs:145: broken MIR in DefId(0:27 ~ vmidi[fa26]::chan_usage[0]::{{impl}}[1]::to_arr[0]) (LocalDecl { mutability: Mut, local_info: None, internal: false, is_block_tail: None, ty: [type error], user_ty: None, source_info: SourceInfo { span: proj\src\chan_usage.rs:145:2: 148:3 (#0), scope: scope[0] } }): bad type [type error]
note: proj\src\chan_usage.rs:145: delayed at src\librustc_mir\borrow_check\type_check\mod.rs:258:27
error: proj\src\chan_usage.rs:146: mir_const_qualif: MIR had errors
note: proj\src\chan_usage.rs:146: delayed at /rustc/ff5b446d2fdbd898bc97a751f2f72858de185cf1\src\librustc_session\session.rs:436:27
error: proj\src\chan_usage.rs:146: PromoteTemps: MIR had errors
note: proj\src\chan_usage.rs:146: delayed at /rustc/ff5b446d2fdbd898bc97a751f2f72858de185cf1\src\librustc_session\session.rs:436:27
error: proj\src\chan_usage.rs:146: broken MIR in DefId(0:29 ~ vmidi[fa26]::chan_usage[0]::{{impl}}[1]::to_arr[0]::{{constant}}[1]) ("return type"): bad type [type error]
note: proj\src\chan_usage.rs:146: delayed at src\librustc_mir\borrow_check\type_check\mod.rs:258:27
error: proj\src\chan_usage.rs:146: broken MIR in DefId(0:29 ~ vmidi[fa26]::chan_usage[0]::{{impl}}[1]::to_arr[0]::{{constant}}[1]) (LocalDecl { mutability: Mut, local_info: None, internal: false, is_block_tail: None, ty: [type error], user_ty: None, source_info: SourceInfo { span: proj\src\chan_usage.rs:146:29: 146:36 (#0), scope: scope[0] } }): bad type [type error]
note: proj\src\chan_usage.rs:146: delayed at src\librustc_mir\borrow_check\type_check\mod.rs:258:27
thread 'rustc' panicked at 'no errors encountered even though `delay_span_bug` issued', src\librustc_errors\lib.rs:367:17
stack backtrace:
   0: <std::sys_common::backtrace::_print::DisplayBacktrace as core::fmt::Display>::fmt
   1: core::fmt::write
   2: <std::io::IoSliceMut as core::fmt::Debug>::fmt
   3: std::panicking::take_hook
   4: std::panicking::take_hook
   5: rustc_driver::report_ice
   6: std::panicking::rust_panic_with_hook
   7: <rustc_errors::styled_buffer::StyledBuffer as core::fmt::Debug>::fmt
   8: <rustc_errors::HandlerInner as core::ops::drop::Drop>::drop
   9: <rustc_ast::ast::Item<rustc_ast::ast::ForeignItemKind> as rustc_ast::attr::HasAttrs>::attrs
  10: <rustc_ast::ast::Item<rustc_ast::ast::ForeignItemKind> as rustc_ast::attr::HasAttrs>::attrs
  11: <rustc_ast_passes::node_count::NodeCounter as rustc_ast::visit::Visitor>::visit_ident
  12: <rustc_metadata::foreign_modules::Collector as rustc_hir::itemlikevisit::ItemLikeVisitor>::visit_impl_item
  13: <rustc_driver::DEFAULT_HOOK as core::ops::deref::Deref>::deref
  14: <rustc_span::symbol::SymbolStr as core::fmt::Display>::fmt
  15: <i16 as petgraph::matrix_graph::Zero>::zero
  16: std::sys::windows::thread::Thread::new
  17: BaseThreadInitThunk
  18: RtlUserThreadStart
note: Some details are omitted, run with `RUST_BACKTRACE=full` for a verbose backtrace.

error: internal compiler error: unexpected panic

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

note: we would appreciate a bug report: https://github.com/rust-lang/rust/blob/master/CONTRIBUTING.md#bug-reports

note: rustc 1.46.0-nightly (ff5b446d2 2020-06-23) running on x86_64-pc-windows-msvc

note: compiler flags: -C opt-level=3 -C panic=abort -C embed-bitcode=no -C debuginfo=2 -C debug-assertions=on -C incremental --crate-type lib

note: some of the compiler flags provided by cargo are hidden

query stack during panic:
end of query stack

[JohnTitor]

It'd be great if we could drop external dependency, marking as E-needs-mcve.

[connorskees]

Slightly minified,

#![feature(const_generics)]
#![allow(dead_code, incomplete_features)]

pub struct ChannelUsage;

impl ChannelUsage {
    fn collect_arr<const N: i32>() {}
}

fn foo() {
    ChannelUsage::collect_arr::<16i32>();
}

Error

rustc --version --verbose
rustc 1.46.0-nightly (a647c0cd6 2020-06-16)
binary: rustc
commit-hash: a647c0cd68bdd0f15081019f0b21bc31ae23f072
commit-date: 2020-06-16
host: x86_64-unknown-linux-gnu
release: 1.46.0-nightly
LLVM version: 10.0

error: internal compiler error: unexpected const parent path Expr(Expr { hir_id: HirId { owner: DefId(0:8 ~ ice[227a]::foo[0]), local_id: 6 }, kind: Path(TypeRelative(Ty { hir_id: HirId { owner: DefId(0:8 ~ ice[227a]::foo[0]), local_id: 2 }, kind: Path(Resolved(None, Path { span: src/lib.rs:11:5: 11:39 (#0), res: Def(Struct, DefId(0:3 ~ ice[227a]::ChannelUsage[0])), segments: [PathSegment { ident: ChannelUsage#0, hir_id: Some(HirId { owner: DefId(0:8 ~ ice[227a]::foo[0]), local_id: 1 }), res: Some(Err), args: None, infer_args: true }] })), span: src/lib.rs:11:5: 11:39 (#0) }, PathSegment { ident: collect_arr#0, hir_id: Some(HirId { owner: DefId(0:8 ~ ice[227a]::foo[0]), local_id: 5 }), res: Some(Err), args: Some(GenericArgs { args: [Const(ConstArg { value: AnonConst { hir_id: HirId { owner: DefId(0:8 ~ ice[227a]::foo[0]), local_id: 3 }, body: BodyId { hir_id: HirId { owner: DefId(0:8 ~ ice[227a]::foo[0]), local_id: 4 } } }, span: src/lib.rs:11:33: 11:38 (#0) })], bindings: [], parenthesized: false }), infer_args: false })), attrs: ThinVec(None), span: src/lib.rs:11:5: 11:39 (#0) })

error: internal compiler error: Const::from_anon_const: couldn't lit_to_const
  --> src/lib.rs:11:33
   |
11 |     ChannelUsage::collect_arr::<16i32>();
   |                                 ^^^^^

error: internal compiler error: `ErrorReported` without an error
  --> src/lib.rs:11:33
   |
11 |     ChannelUsage::collect_arr::<16i32>();
   |                                 ^^^^^

error: internal compiler error: cat_expr Errd
  --> src/lib.rs:10:10
   |
10 |   fn foo() {
   |  __________^
11 | |     ChannelUsage::collect_arr::<16i32>();
12 | | }
   | |_^

error: internal compiler error: cat_expr Errd
  --> src/lib.rs:11:5
   |
11 |     ChannelUsage::collect_arr::<16i32>();
   |     ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^

error: internal compiler error: PromoteTemps: MIR had errors
  --> src/lib.rs:10:1
   |
10 | / fn foo() {
11 | |     ChannelUsage::collect_arr::<16i32>();
12 | | }
   | |_^

error: internal compiler error: broken MIR in DefId(0:8 ~ ice[227a]::foo[0]) ("return type"): bad type [type error]
  --> src/lib.rs:10:1
   |
10 | / fn foo() {
11 | |     ChannelUsage::collect_arr::<16i32>();
12 | | }
   | |_^

error: internal compiler error: broken MIR in DefId(0:8 ~ ice[227a]::foo[0]) (LocalDecl { mutability: Mut, local_info: None, internal: false, is_block_tail: None, ty: [type error], user_ty: None, source_info: SourceInfo { span: src/lib.rs:10:1: 12:2 (#0), scope: scope[0] } }): bad type [type error]
  --> src/lib.rs:10:1
   |
10 | / fn foo() {
11 | |     ChannelUsage::collect_arr::<16i32>();
12 | | }
   | |_^

error: internal compiler error: mir_const_qualif: MIR had errors
  --> src/lib.rs:11:33
   |
11 |     ChannelUsage::collect_arr::<16i32>();
   |                                 ^^^^^

error: internal compiler error: PromoteTemps: MIR had errors
  --> src/lib.rs:11:33
   |
11 |     ChannelUsage::collect_arr::<16i32>();
   |                                 ^^^^^

error: internal compiler error: broken MIR in DefId(0:9 ~ ice[227a]::foo[0]::{{constant}}[0]) ("return type"): bad type [type error]
  --> src/lib.rs:11:33
   |
11 |     ChannelUsage::collect_arr::<16i32>();
   |                                 ^^^^^

error: internal compiler error: broken MIR in DefId(0:9 ~ ice[227a]::foo[0]::{{constant}}[0]) (LocalDecl { mutability: Mut, local_info: None, internal: false, is_block_tail: None, ty: [type error], user_ty: None, source_info: SourceInfo { span: src/lib.rs:11:33: 11:38 (#0), scope: scope[0] } }): bad type [type error]
  --> src/lib.rs:11:33
   |
11 |     ChannelUsage::collect_arr::<16i32>();
   |                                 ^^^^^

thread 'rustc' panicked at 'no errors encountered even though `delay_span_bug` issued', src/librustc_errors/lib.rs:366:17
note: run with `RUST_BACKTRACE=1` environment variable to display a backtrace

error: internal compiler error: unexpected panic

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

note: we would appreciate a bug report: https://github.com/rust-lang/rust/blob/master/CONTRIBUTING.md#bug-reports

note: rustc 1.46.0-nightly (a647c0cd6 2020-06-16) running on x86_64-unknown-linux-gnu

note: compiler flags: -C embed-bitcode=no -C debuginfo=2 -C incremental --crate-type lib

note: some of the compiler flags provided by cargo are hidden

playground

[lcnr]

should be fixed by #74113 and we already have a nearly identical test to the mcve by @connorskees

@Boscop In case your original example is also fixed, please close this issue.

[lcnr]

Closing as I expect this to be fixed, in case the issue persists don't hesitate to open a new issue.