ICE: `Encountered unexpected type in ConstructorSet::for_ty` in `rustc_pattern_analysis/src/rustc.rs`

[cushionbadak]

Code

(hand reduced)

pub trait A {}

pub trait Mirror {
    type Assoc: ?Sized;
}
impl<T: ?Sized> Mirror for dyn A {
    type Assoc = T;
}

struct Bar {
    foo: <dyn A + 'static as Mirror>::Assoc,
}

pub fn main() {
    let strct = Bar { foo: 3 };

    match strct {
        Bar { foo: 1, .. } => {}
        _ => (),
    };
}

• Compared to original code, keyword dyn added at impl<T: ?Sized> Mirror for dyn A, to reduce error message.

original code

pub trait A {}
pub trait B: A {}

pub trait Mirror {
    type Assoc: ?Sized;
}
impl<T: ?Sized> Mirror for A {
    type Assoc = T;
}

pub fn foo<'a>(x: &'a <dyn A + 'static as Mirror>::Assoc) -> &'a <dyn B + 'static as Mirror>::Assoc {
    static
}


//@ run-pass

#![feature(postfix_match)]

struct Bar {
    foo: <dyn A + 'static as Mirror>::Assoc,
    baz: u8,
}

pub fn main() {
    let thing = Some("thing");

    thing.match {
        Some("nothing") => {},
        Some(text) if text.eq_ignore_ascii_case("tapir")  => {},
        Some("true") | Some("false") => {},
        Some("thing") => {},
        Some(_) => {},
        None => {}
    };

    let num = 2u8;

    num.match {
        0 => {},
        1..=5 => {},
        _ => {},
    };

    let slic = &[1, 2, 3, 4][..];

    slic.match {
        [1] => {},
        [2, _tail @ ..] => {},
        [1, _] => {},
        _ => {},
    };

    slic[0].match {
        1 => 0,
        i => i,
    };

    let out = (1, 2).match {
        (1, 3) => 0,
        (_, 1) => 0,
        (1, i) => i,
        _ => 3,
    };
    assert!(out == 2);

    let strct = Bar {
        foo: 3,
        baz: 4
    };

    strct.match {
        Bar { foo: 1, .. } => {},
        Bar { baz: 2, .. } => {},
        _ => (),
    };
}

Meta

rustc --version --verbose:

rustc 1.80.0-nightly (f67a1acc0 2024-06-01)
binary: rustc
commit-hash: f67a1acc04c7ecbf05751b17592dd8d245b75256
commit-date: 2024-06-01
host: aarch64-apple-darwin
release: 1.80.0-nightly
LLVM version: 18.1.6

Error output

Command: rustc

error[E0207]: the type parameter `T` is not constrained by the impl trait, self type, or predicates
 --> r_rustc_1A93F6.rs:6:6
  |
6 | impl<T: ?Sized> Mirror for dyn A {
  |      ^ unconstrained type parameter

error[E0282]: type annotations needed
  --> r_rustc_1A93F6.rs:11:10
   |
11 |     foo: <dyn A + 'static as Mirror>::Assoc,
   |          ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^ cannot infer type for type parameter `T`

Backtrace

error: internal compiler error: compiler/rustc_pattern_analysis/src/rustc.rs:412:17: Encountered unexpected type in `ConstructorSet::for_ty`: ?0t

thread 'rustc' panicked at compiler/rustc_pattern_analysis/src/rustc.rs:412:17:
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<rustc_span::span_encoding::Span>::{closure#0}, !>::{closure#0}, !>
   5: rustc_middle::util::bug::bug_fmt
   6: <rustc_pattern_analysis::rustc::RustcPatCtxt>::ctors_for_ty
   7: rustc_pattern_analysis::usefulness::compute_exhaustiveness_and_usefulness::<rustc_pattern_analysis::rustc::RustcPatCtxt>
   8: rustc_pattern_analysis::usefulness::compute_exhaustiveness_and_usefulness::<rustc_pattern_analysis::rustc::RustcPatCtxt>
   9: rustc_pattern_analysis::usefulness::compute_match_usefulness::<rustc_pattern_analysis::rustc::RustcPatCtxt>
  10: rustc_pattern_analysis::analyze_match
  11: <rustc_mir_build::thir::pattern::check_match::MatchVisitor>::analyze_patterns
  12: <rustc_mir_build::thir::pattern::check_match::MatchVisitor>::check_match
  13: <rustc_mir_build::thir::pattern::check_match::MatchVisitor as rustc_middle::thir::visit::Visitor>::visit_expr
  14: <rustc_mir_build::thir::pattern::check_match::MatchVisitor as rustc_middle::thir::visit::Visitor>::visit_expr
  15: rustc_middle::thir::visit::walk_expr::<rustc_mir_build::thir::pattern::check_match::MatchVisitor>
  16: <rustc_mir_build::thir::pattern::check_match::MatchVisitor as rustc_middle::thir::visit::Visitor>::visit_expr
  17: <rustc_mir_build::thir::pattern::check_match::MatchVisitor as rustc_middle::thir::visit::Visitor>::visit_expr
  18: rustc_mir_build::thir::pattern::check_match::check_match
      [... omitted 2 frames ...]
  19: rustc_mir_build::build::mir_build
  20: rustc_mir_transform::mir_built
      [... omitted 2 frames ...]
  21: rustc_mir_build::check_unsafety::check_unsafety
      [... omitted 2 frames ...]
  22: <rustc_middle::hir::map::Map>::par_body_owners::<rustc_interface::passes::run_required_analyses::{closure#1}::{closure#0}>::{closure#0}
  23: <rustc_data_structures::sync::parallel::ParallelGuard>::run::<(), rustc_data_structures::sync::parallel::enabled::par_for_each_in<&rustc_span::def_id::LocalDefId, &[rustc_span::def_id::LocalDefId], <rustc_middle::hir::map::Map>::par_body_owners<rustc_interface::passes::run_required_analyses::{closure#1}::{closure#0}>::{closure#0}>::{closure#0}::{closure#0}::{closure#0}>
  24: <rustc_session::session::Session>::time::<(), rustc_interface::passes::run_required_analyses::{closure#1}>
  25: rustc_interface::passes::analysis
      [... omitted 2 frames ...]
  26: <rustc_interface::queries::QueryResult<&rustc_middle::ty::context::GlobalCtxt>>::enter::<core::result::Result<(), rustc_span::ErrorGuaranteed>, rustc_driver_impl::run_compiler::{closure#0}::{closure#1}::{closure#3}>
  27: <rustc_interface::interface::Compiler>::enter::<rustc_driver_impl::run_compiler::{closure#0}::{closure#1}, core::result::Result<core::option::Option<rustc_interface::queries::Linker>, rustc_span::ErrorGuaranteed>>
  28: <scoped_tls::ScopedKey<rustc_span::SessionGlobals>>::set::<rustc_interface::util::run_in_thread_with_globals<rustc_interface::util::run_in_thread_pool_with_globals<rustc_interface::interface::run_compiler<core::result::Result<(), rustc_span::ErrorGuaranteed>, rustc_driver_impl::run_compiler::{closure#0}>::{closure#1}, core::result::Result<(), rustc_span::ErrorGuaranteed>>::{closure#0}, core::result::Result<(), rustc_span::ErrorGuaranteed>>::{closure#0}::{closure#0}::{closure#0}, core::result::Result<(), rustc_span::ErrorGuaranteed>>
note: Some details are omitted, run with `RUST_BACKTRACE=full` for a verbose backtrace.

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: please make sure that you have updated to the latest nightly

note: please attach the file at `/Users/jisukbyun/workspace/240531_100chaos_tree_combine_typ/icefiles/rustc-ice-2024-06-02T02_04_15-52985.txt` to your bug report

query stack during panic:
#0 [check_match] match-checking `main`
#1 [mir_built] building MIR for `main`
#2 [check_unsafety] unsafety-checking `main`
#3 [analysis] running analysis passes on this crate
end of query stack
error: aborting due to 3 previous errors

Some errors have detailed explanations: E0207, E0282.
For more information about an error, try `rustc --explain E0207`.

Note

• ICE location: rustc_pattern_analysis/src/rustc.rs L412
  

  rust/compiler/rustc_pattern_analysis/src/rustc.rs

  Lines 411 to 413 in f67a1ac

  	ty::CoroutineWitness(_, _) | ty::Bound(_, _) | ty::Placeholder(_) | ty::Infer(_) => {
  	bug!("Encountered unexpected type in `ConstructorSet::for_ty`: {ty:?}")
  	}

[cushionbadak]

searched nightlies: from nightly-2023-01-01 to nightly-2024-05-30
regressed nightly: nightly-2024-03-08
searched commit range: 7d3702e...9c3ad80
regressed commit: 8c9a75b

bisected with cargo-bisect-rustc v0.6.8

Host triple: x86_64-unknown-linux-gnu
Reproduce with:

cargo bisect-rustc --start=2023-01-01 --end=2024-05-30 --regress=ice --script=rustc --preserve -- 125874.rs