rust-lang / rust-lang/rust

Broken MIR in DefId (TerminatorKind::Call with GATs)

Open
#131,373 2 comments 0 reactions 0 assignees View on GitHub

Nobody has claimed this yet.

A-GATs C-bug fixed-by-next-solver I-ICE S-bug-has-test T-compiler T-types
Dominant language
Rust
Stars
119k
Forks
16.1k
PR metrics pending

Description

Code
struct Ref<T>(T);

trait Reference: 'static {
    type Ref<'a>;
    fn get_ref(&self) -> Self::Ref<'_>;
}

trait Lock: 'static {
    type Locked<'a>;
    fn locked(&self) -> Self::Locked<'_>;
}

struct SliceRef<'a, T: ?Sized> {
    inner: &'a T
}

impl<'a, 'b, T: ?Sized, SR: Reference> IntoIterator for &'b SliceRef<'a, T> where &'a T: IntoIterator<Item=&'a SR> {
    type Item = SR::Ref<'a>;
    type IntoIter = std::iter::Map<<&'a T as IntoIterator>::IntoIter, for<'c> fn(&'c SR) -> SR::Ref<'c>>;
    fn into_iter(self) -> Self::IntoIter {
        self.inner.into_iter().map(|cr| { cr.get_ref() })
    }
}

impl<SR: Reference> Reference for Vec<SR> {
    type Ref<'a> = SliceRef<'a, [SR]>;
    fn get_ref(&self) -> Self::Ref<'_> {
        SliceRef {
            inner: &**self,
        }
    }
}

impl<SR: Reference> Lock for Ref<SR> {
    type Locked<'a> = SR::Ref<'a>;
    fn locked(&self) -> Self::Locked<'_> {
        self.0.get_ref()
    }
}

impl Reference for () {
    type Ref<'a> = &'a ();
    fn get_ref(&self) -> Self::Ref<'_> {
        unimplemented!()
    }
}

fn main() {
    let data = Ref(Vec::<()>::new());
    let _ = (&data.locked()).into_iter();
}
Meta

rustc --version --verbose:

rustc 1.81.0 (eeb90cda1 2024-09-04)
binary: rustc
commit-hash: eeb90cda1969383f56a2637cbd3037bdf598841c
commit-date: 2024-09-04
host: x86_64-pc-windows-msvc
release: 1.81.0
LLVM version: 18.1.7
Error output
error: internal compiler error: broken MIR in DefId(0:43 ~ tester[0e95]::main) (Terminator { source_info: SourceInfo { span: src/main.rs:50:13: 50:41 (#0), scope: scope[1] }, kind: _3 = <&SliceRef<'_, [()]> as IntoIterator>::into_iter(move _4) -> [return: bb4, unwind: bb6] }): call dest mismatch (std::iter::Map<std::slice::Iter<'?7, ()>, Binder { value: fn(&'^0.Named(DefId(0:26 ~ tester[0e95]::{impl#0}::IntoIter::'c), "'c") ()) -> &'^0.Named(DefId(0:26 ~ tester[0e95]::{impl#0}::IntoIter::'c), "'c") (), bound_vars: [Region(BrNamed(DefId(0:26 ~ tester[0e95]::{impl#0}::IntoIter::'c), 'c))] }> <- std::iter::Map<std::slice::Iter<'?6, ()>, Binder { value: fn(&'^0.Named(DefId(0:26 ~ tester[0e95]::{impl#0}::IntoIter::'c), "'c") ()) -> Alias(Projection, AliasTy { args: [(), '^0.Named(DefId(0:26 ~ tester[0e95]::{impl#0}::IntoIter::'c), "'c")], def_id: DefId(0:8 ~ tester[0e95]::Reference::Ref) }), bound_vars: [Region(BrNamed(DefId(0:26 ~ tester[0e95]::{impl#0}::IntoIter::'c), 'c))] }>): NoSolution
  --> src/main.rs:50:13
   |
50 |     let _ = (&data.locked()).into_iter();
   |             ^^^^^^^^^^^^^^^^
   |
note: delayed at compiler\rustc_borrowck\src\type_check\mod.rs:1571:21
         0: std::backtrace_rs::backtrace::dbghelp64::trace
                   at /rustc/eeb90cda1969383f56a2637cbd3037bdf598841c/library\std\src\..\..\backtrace\src\backtrace\dbghelp64.rs:91
         1: std::backtrace_rs::backtrace::trace_unsynchronized
                   at /rustc/eeb90cda1969383f56a2637cbd3037bdf598841c/library\std\src\..\..\backtrace\src\backtrace\mod.rs:66
         2: std::backtrace::Backtrace::create
                   at /rustc/eeb90cda1969383f56a2637cbd3037bdf598841c/library\std\src\backtrace.rs:331
         3: std::backtrace::Backtrace::capture
                   at /rustc/eeb90cda1969383f56a2637cbd3037bdf598841c/library\std\src\backtrace.rs:296
         4: <rustc_errors::DiagCtxtHandle>::steal_fulfilled_expectation_ids
         5: <rustc_errors::DiagCtxtHandle>::emit_diagnostic
         6: <rustc_span::ErrorGuaranteed as rustc_errors::diagnostic::EmissionGuarantee>::emit_producing_guarantee
         7: <rustc_pattern_analysis::errors::NonExhaustiveOmittedPatternLintOnArm as rustc_errors::diagnostic::LintDiagnostic<()>>::decorate_lint
         8: <rustc_borrowck::type_check::TypeChecker>::push_region_constraints
         9: rustc_borrowck::dataflow::calculate_borrows_out_of_scope_at_location
        10: rustc_borrowck::dataflow::calculate_borrows_out_of_scope_at_location
        11: <rustc_borrowck::type_check::TypeChecker>::push_region_constraints
        12: rustc_borrowck::mir_borrowck
        13: rustc_query_impl::plumbing::query_key_hash_verify_all
        14: rustc_ty_utils::ty::self_ty_of_trait_impl_enabling_order_dep_trait_object_hack
        15: rustc_query_impl::plumbing::query_key_hash_verify_all
        16: rustc_interface::passes::analysis
        17: rustc_ty_utils::ty::adt_sized_constraint
        18: rustc_ty_utils::ty::adt_sized_constraint
        19: rustc_query_impl::query_system
        20: _LNan_C
        21: _LNan_C
        22: _LNan_C
        23: alloc::boxed::impl$48::call_once
                   at /rustc/eeb90cda1969383f56a2637cbd3037bdf598841c/library\alloc\src\boxed.rs:2070
        24: alloc::boxed::impl$48::call_once
                   at /rustc/eeb90cda1969383f56a2637cbd3037bdf598841c/library\alloc\src\boxed.rs:2070
        25: std::sys::pal::windows::thread::impl$0::new::thread_start
                   at /rustc/eeb90cda1969383f56a2637cbd3037bdf598841c/library\std\src\sys\pal\windows\thread.rs:58
        26: BaseThreadInitThunk
        27: RtlUserThreadStart
  --> src/main.rs:50:13
   |
50 |     let _ = (&data.locked()).into_iter();
   |             ^^^^^^^^^^^^^^^^
Backtrace 

   Compiling tester v0.1.0 (C:\Users\BLUEM\rust\tester)
note: no errors encountered even though delayed bugs were created                                                                                                                                                                  

note: those delayed bugs will now be shown as internal compiler errors

error: internal compiler error: broken MIR in DefId(0:43 ~ tester[0e95]::main) (Terminator { source_info: SourceInfo { span: src/main.rs:50:13: 50:41 (#0), scope: scope[1] }, kind: _3 = <&SliceRef<'_, [()]> as IntoIterator>::int
o_iter(move _4) -> [return: bb4, unwind: bb6] }): call dest mismatch (std::iter::Map<std::slice::Iter<'?7, ()>, Binder { value: fn(&'^0.Named(DefId(0:26 ~ tester[0e95]::{impl#0}::IntoIter::'c), "'c") ()) -> &'^0.Named(DefId(0:26
 ~ tester[0e95]::{impl#0}::IntoIter::'c), "'c") (), bound_vars: [Region(BrNamed(DefId(0:26 ~ tester[0e95]::{impl#0}::IntoIter::'c), 'c))] }> <- std::iter::Map<std::slice::Iter<'?6, ()>, Binder { value: fn(&'^0.Named(DefId(0:26 ~
 tester[0e95]::{impl#0}::IntoIter::'c), "'c") ()) -> Alias(Projection, AliasTy { args: [(), '^0.Named(DefId(0:26 ~ tester[0e95]::{impl#0}::IntoIter::'c), "'c")], def_id: DefId(0:8 ~ tester[0e95]::Reference::Ref) }), bound_vars: [Region(BrNamed(DefId(0:26 ~ tester[0e95]::{impl#0}::IntoIter::'c), 'c))] }>): NoSolution
  --> src/main.rs:50:13
   |
50 |     let _ = (&data.locked()).into_iter();
   |             ^^^^^^^^^^^^^^^^
   |
note: delayed at compiler\rustc_borrowck\src\type_check\mod.rs:1571:21
         0: std::backtrace_rs::backtrace::dbghelp64::trace
                   at /rustc/eeb90cda1969383f56a2637cbd3037bdf598841c/library\std\src\..\..\backtrace\src\backtrace\dbghelp64.rs:91
         1: std::backtrace_rs::backtrace::trace_unsynchronized
                   at /rustc/eeb90cda1969383f56a2637cbd3037bdf598841c/library\std\src\..\..\backtrace\src\backtrace\mod.rs:66
         2: std::backtrace::Backtrace::create
                   at /rustc/eeb90cda1969383f56a2637cbd3037bdf598841c/library\std\src\backtrace.rs:331
         3: std::backtrace::Backtrace::capture
                   at /rustc/eeb90cda1969383f56a2637cbd3037bdf598841c/library\std\src\backtrace.rs:296
         4: <rustc_errors::DiagCtxtHandle>::steal_fulfilled_expectation_ids
         5: <rustc_errors::DiagCtxtHandle>::emit_diagnostic
         6: <rustc_span::ErrorGuaranteed as rustc_errors::diagnostic::EmissionGuarantee>::emit_producing_guarantee
         7: <rustc_pattern_analysis::errors::NonExhaustiveOmittedPatternLintOnArm as rustc_errors::diagnostic::LintDiagnostic<()>>::decorate_lint
         8: <rustc_borrowck::type_check::TypeChecker>::push_region_constraints
         9: rustc_borrowck::dataflow::calculate_borrows_out_of_scope_at_location
        10: rustc_borrowck::dataflow::calculate_borrows_out_of_scope_at_location
        11: <rustc_borrowck::type_check::TypeChecker>::push_region_constraints
        12: rustc_borrowck::mir_borrowck
        13: rustc_query_impl::plumbing::query_key_hash_verify_all
        14: rustc_ty_utils::ty::self_ty_of_trait_impl_enabling_order_dep_trait_object_hack
        15: rustc_query_impl::plumbing::query_key_hash_verify_all
        16: rustc_interface::passes::analysis
        17: rustc_ty_utils::ty::adt_sized_constraint
        18: rustc_ty_utils::ty::adt_sized_constraint
        19: rustc_query_impl::query_system
        20: _LNan_C
        21: _LNan_C
        22: _LNan_C
        23: alloc::boxed::impl$48::call_once
                   at /rustc/eeb90cda1969383f56a2637cbd3037bdf598841c/library\alloc\src\boxed.rs:2070
        24: alloc::boxed::impl$48::call_once
                   at /rustc/eeb90cda1969383f56a2637cbd3037bdf598841c/library\alloc\src\boxed.rs:2070
        25: std::sys::pal::windows::thread::impl$0::new::thread_start
                   at /rustc/eeb90cda1969383f56a2637cbd3037bdf598841c/library\std\src\sys\pal\windows\thread.rs:58
        26: BaseThreadInitThunk
        27: RtlUserThreadStart
  --> src/main.rs:50:13
   |
50 |     let _ = (&data.locked()).into_iter();
   |             ^^^^^^^^^^^^^^^^

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 1.81.0 (eeb90cda1 2024-09-04) running on x86_64-pc-windows-msvc

note: compiler flags: --crate-type bin -C embed-bitcode=no -C debuginfo=2 -C incremental=[REDACTED]

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

query stack during panic:
end of query stack
error: could not compile `tester` (bin "tester")

Contributor guide

Open the contributing guide

First steps

  1. Read the whole issue, then the project's contributing guide.
  2. Comment on the issue to say you are picking it up — it saves two people doing the same work.
  3. Fork the repository and make your change on a branch.
  4. Open a pull request that references the issue number.

Research direction

Start with the reproducer in src/main.rs and compile it with the reported rustc 1.81.0 configuration to confirm the internal compiler error. Then read the delayed diagnostic location in compiler/rustc_borrowck/src/type_check/mod.rs:1571 and trace the broken MIR report. Done means the reproducer no longer produces broken MIR or an internal compiler error.

Written by the indexing model from the issue text.

Assessment

Tech stack
rust
Domain
compilers
Issue type
Bug
Difficulty
5/5
Estimated time
Over a week
Activity status
Stale
Clarity
Needs clarification
Newbie friendliness
30/100

Get new issues in your inbox

A short digest of beginner-friendly GitHub issues.