[BUG REPORT]: Internal Compiler Error on stable surrounding type inference #71955

vcfxb · 2020-05-06T18:33:43Z

Stable rust throws an internal compiler error (ICE) that appears to be related to type inference surrounding higher rank trait bounds (HRTBs) and associated types.

Code:

playground

trait Parser<'s> {
    type Output;
    
    fn call(&self, input: &'s str) -> (&'s str, Self::Output);
}

impl<'s, F, T> Parser<'s> for F
where F: Fn(&'s str) -> (&'s str, T) {
    type Output = T;
    fn call(&self, input: &'s str) -> (&'s str, T) {
        self(input)
    }
}

fn foo<F1, F2>(
    f1: F1,
    base: &'static str,
    f2: F2
) 
where 
    F1: for<'a> Parser<'a>,
    F2: FnOnce(&<F1 as Parser>::Output) -> bool
{
    let s: String = base.to_owned();
    let str_ref = s.as_ref();
    let (remaining, produced) = f1.call(str_ref);
    assert!(f2(&produced));
    assert_eq!(remaining.len(), 0);
}

struct Wrapper<'a>(&'a str);

fn main() {
    fn bar<'a>(s: &'a str) -> (&'a str, &'a str) {
        (&s[..1], &s[..])
    }
    
    fn baz<'a>(s: &'a str) -> (&'a str, Wrapper<'a>) {
        (&s[..1], Wrapper(&s[..]))
    }
    
    foo(bar, "string", |s| s.len() == 5);
    foo(baz, "string", |s| s.0.len() == 5);
}

Expectaions:

I expected this code to compile and run smoothly, without throwing any errors at compile time or runtime.

Result

Instead, this happened:

   Compiling playground v0.0.1 (/playground)
error: internal compiler error: src/librustc_infer/traits/codegen/mod.rs:61: Encountered error `OutputTypeParameterMismatch(Binder(<[closure@src/main.rs:43:24: 43:40] as std::ops::FnOnce<(&<for<'a> fn(&'a str) -> (&'a str, &'a str) {main::bar} as Parser<'_>>::Output,)>>), Binder(<[closure@src/main.rs:43:24: 43:40] as std::ops::FnOnce<(&&str,)>>), Sorts(ExpectedFound { expected: &str, found: <for<'a> fn(&'a str) -> (&'a str, &'a str) {main::bar} as Parser<'_>>::Output }))` selecting `Binder(<[closure@src/main.rs:43:24: 43:40] as std::ops::FnOnce<(&&str,)>>)` during codegen

thread 'rustc' panicked at 'Box<Any>', src/librustc_errors/lib.rs:875:9
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/blob/master/CONTRIBUTING.md#bug-reports

note: rustc 1.43.0 (4fb7144ed 2020-04-20) running on x86_64-unknown-linux-gnu

note: compiler flags: -C codegen-units=1 -C debuginfo=2 --crate-type bin

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

error: aborting due to previous error

error: could not compile `playground`.

To learn more, run the command again with --verbose.

Meta

Rust version: this is running on the playground on the stable version.

On my local machine (which gives the same output) rust --version --verbose:

rustc 1.43.0 (4fb7144ed 2020-04-20)
binary: rustc
commit-hash: 4fb7144ed159f94491249e86d5bbd033b5d60550
commit-date: 2020-04-20
host: x86_64-unknown-linux-gnu
release: 1.43.0
LLVM version: 9.0

Backtrace (on playground):

  Compiling playground v0.0.1 (/playground)
error: internal compiler error: src/librustc_infer/traits/codegen/mod.rs:61: Encountered error `OutputTypeParameterMismatch(Binder(<[closure@src/main.rs:43:24: 43:40] as std::ops::FnOnce<(&<for<'a> fn(&'a str) -> (&'a str, &'a str) {main::bar} as Parser<'_>>::Output,)>>), Binder(<[closure@src/main.rs:43:24: 43:40] as std::ops::FnOnce<(&&str,)>>), Sorts(ExpectedFound { expected: &str, found: <for<'a> fn(&'a str) -> (&'a str, &'a str) {main::bar} as Parser<'_>>::Output }))` selecting `Binder(<[closure@src/main.rs:43:24: 43:40] as std::ops::FnOnce<(&&str,)>>)` during codegen

thread 'rustc' panicked at 'Box<Any>', src/librustc_errors/lib.rs:875:9
stack backtrace:
   0: backtrace::backtrace::libunwind::trace
             at /cargo/registry/src/github.com-1ecc6299db9ec823/backtrace-0.3.44/src/backtrace/libunwind.rs:86
   1: backtrace::backtrace::trace_unsynchronized
             at /cargo/registry/src/github.com-1ecc6299db9ec823/backtrace-0.3.44/src/backtrace/mod.rs:66
   2: std::sys_common::backtrace::_print_fmt
             at src/libstd/sys_common/backtrace.rs:78
   3: <std::sys_common::backtrace::_print::DisplayBacktrace as core::fmt::Display>::fmt
             at src/libstd/sys_common/backtrace.rs:59
   4: core::fmt::write
             at src/libcore/fmt/mod.rs:1063
   5: std::io::Write::write_fmt
             at src/libstd/io/mod.rs:1426
   6: std::sys_common::backtrace::_print
             at src/libstd/sys_common/backtrace.rs:62
   7: std::sys_common::backtrace::print
             at src/libstd/sys_common/backtrace.rs:49
   8: std::panicking::default_hook::{{closure}}
             at src/libstd/panicking.rs:204
   9: std::panicking::default_hook
             at src/libstd/panicking.rs:224
  10: rustc_driver::report_ice
  11: std::panicking::rust_panic_with_hook
             at src/libstd/panicking.rs:474
  12: std::panicking::begin_panic
  13: rustc_errors::HandlerInner::bug
  14: rustc_errors::Handler::bug
  15: rustc::util::bug::opt_span_bug_fmt::{{closure}}
  16: rustc::ty::context::tls::with_opt::{{closure}}
  17: rustc::ty::context::tls::with_opt
  18: rustc::util::bug::opt_span_bug_fmt
  19: rustc::util::bug::bug_fmt
  20: rustc::ty::context::GlobalCtxt::enter_local
  21: rustc_infer::traits::codegen::codegen_fulfill_obligation
  22: rustc::ty::query::__query_compute::codegen_fulfill_obligation
  23: rustc::ty::query::<impl rustc::ty::query::config::QueryAccessors for rustc::ty::query::queries::codegen_fulfill_obligation>::compute
  24: rustc::dep_graph::graph::DepGraph::with_task_impl
  25: rustc::ty::query::plumbing::<impl rustc::ty::context::TyCtxt>::get_query
  26: rustc_ty::instance::resolve_instance
  27: rustc::ty::instance::Instance::resolve
  28: <rustc_mir::monomorphize::collector::MirNeighborCollector as rustc::mir::visit::Visitor>::visit_terminator_kind
  29: rustc_mir::monomorphize::collector::collect_items_rec
  30: rustc_mir::monomorphize::collector::collect_items_rec
  31: rustc_session::utils::<impl rustc_session::session::Session>::time
  32: rustc_mir::monomorphize::collector::collect_crate_mono_items
  33: rustc_mir::monomorphize::partitioning::collect_and_partition_mono_items
  34: rustc::ty::query::__query_compute::collect_and_partition_mono_items
  35: rustc::dep_graph::graph::DepGraph::with_task_impl
  36: rustc::ty::query::plumbing::<impl rustc::ty::context::TyCtxt>::get_query
  37: rustc_codegen_ssa::base::codegen_crate
  38: <rustc_codegen_llvm::LlvmCodegenBackend as rustc_codegen_utils::codegen_backend::CodegenBackend>::codegen_crate
  39: rustc_interface::passes::start_codegen
  40: rustc::ty::context::tls::enter_global
  41: rustc_interface::queries::Queries::ongoing_codegen
  42: rustc_interface::interface::run_compiler_in_existing_thread_pool
note: Some details are omitted, run with `RUST_BACKTRACE=full` for a verbose backtrace.

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 1.43.0 (4fb7144ed 2020-04-20) running on x86_64-unknown-linux-gnu

note: compiler flags: -C codegen-units=1 -C debuginfo=2 --crate-type bin

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

query stack during panic:
#0 [codegen_fulfill_obligation] checking if `std::ops::FnOnce` fulfills its obligations
#1 [collect_and_partition_mono_items] collect_and_partition_mono_items
end of query stack
error: aborting due to previous error

error: could not compile `playground`.

To learn more, run the command again with --verbose.

Backtrace (with verbose enabled) (on my local machine):

$ RUST_BACKTRACE=1 rustc --verbose ICE.rs
error: internal compiler error: src/librustc_infer/traits/codegen/mod.rs:61: Encountered error `OutputTypeParameterMismatch(Binder(<[closure@ICE.rs:43:24: 43:40] as std::ops::FnOnce<(&<for<'a> fn(&'a str) -> (&'a str, &'a str) {main::bar} as Parser<'_>>::Output,)>>), Binder(<[closure@ICE.rs:43:24: 43:40] as std::ops::FnOnce<(&&str,)>>), Sorts(ExpectedFound { expected: &str, found: <for<'a> fn(&'a str) -> (&'a str, &'a str) {main::bar} as Parser<'_>>::Output }))` selecting `Binder(<[closure@ICE.rs:43:24: 43:40] as std::ops::FnOnce<(&&str,)>>)` during codegen

thread 'rustc' panicked at 'Box<Any>', src/librustc_errors/lib.rs:875:9
stack backtrace:
   0: backtrace::backtrace::libunwind::trace
             at /cargo/registry/src/github.com-1ecc6299db9ec823/backtrace-0.3.44/src/backtrace/libunwind.rs:86
   1: backtrace::backtrace::trace_unsynchronized
             at /cargo/registry/src/github.com-1ecc6299db9ec823/backtrace-0.3.44/src/backtrace/mod.rs:66
   2: std::sys_common::backtrace::_print_fmt
             at src/libstd/sys_common/backtrace.rs:78
   3: <std::sys_common::backtrace::_print::DisplayBacktrace as core::fmt::Display>::fmt
             at src/libstd/sys_common/backtrace.rs:59
   4: core::fmt::write
             at src/libcore/fmt/mod.rs:1063
   5: std::io::Write::write_fmt
             at src/libstd/io/mod.rs:1426
   6: std::sys_common::backtrace::_print
             at src/libstd/sys_common/backtrace.rs:62
   7: std::sys_common::backtrace::print
             at src/libstd/sys_common/backtrace.rs:49
   8: std::panicking::default_hook::{{closure}}
             at src/libstd/panicking.rs:204
   9: std::panicking::default_hook
             at src/libstd/panicking.rs:224
  10: rustc_driver::report_ice
  11: std::panicking::rust_panic_with_hook
             at src/libstd/panicking.rs:474
  12: std::panicking::begin_panic
  13: rustc_errors::HandlerInner::bug
  14: rustc_errors::Handler::bug
  15: rustc::util::bug::opt_span_bug_fmt::{{closure}}
  16: rustc::ty::context::tls::with_opt::{{closure}}
  17: rustc::ty::context::tls::with_opt
  18: rustc::util::bug::opt_span_bug_fmt
  19: rustc::util::bug::bug_fmt
  20: rustc::ty::context::GlobalCtxt::enter_local
  21: rustc_infer::traits::codegen::codegen_fulfill_obligation
  22: rustc::ty::query::__query_compute::codegen_fulfill_obligation
  23: rustc::ty::query::<impl rustc::ty::query::config::QueryAccessors for rustc::ty::query::queries::codegen_fulfill_obligation>::compute
  24: rustc::dep_graph::graph::DepGraph::with_task_impl
  25: rustc::ty::query::plumbing::<impl rustc::ty::context::TyCtxt>::get_query
  26: rustc_ty::instance::resolve_instance
  27: rustc::ty::instance::Instance::resolve
  28: <rustc_mir::monomorphize::collector::MirNeighborCollector as rustc::mir::visit::Visitor>::visit_terminator_kind
  29: rustc_mir::monomorphize::collector::collect_items_rec
  30: rustc_mir::monomorphize::collector::collect_items_rec
  31: rustc_session::utils::<impl rustc_session::session::Session>::time
  32: rustc_mir::monomorphize::collector::collect_crate_mono_items
  33: rustc_mir::monomorphize::partitioning::collect_and_partition_mono_items
  34: rustc::ty::query::__query_compute::collect_and_partition_mono_items
  35: rustc::dep_graph::graph::DepGraph::with_task_impl
  36: rustc::ty::query::plumbing::<impl rustc::ty::context::TyCtxt>::get_query
  37: rustc_codegen_ssa::base::codegen_crate
  38: <rustc_codegen_llvm::LlvmCodegenBackend as rustc_codegen_utils::codegen_backend::CodegenBackend>::codegen_crate
  39: rustc_interface::passes::start_codegen
  40: rustc::ty::context::tls::enter_global
  41: rustc_interface::queries::Queries::ongoing_codegen
  42: rustc_interface::interface::run_compiler_in_existing_thread_pool
note: Some details are omitted, run with `RUST_BACKTRACE=full` for a verbose backtrace.

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 1.43.0 (4fb7144ed 2020-04-20) running on x86_64-unknown-linux-gnu

query stack during panic:
#0 [codegen_fulfill_obligation] checking if `std::ops::FnOnce` fulfills its obligations
#1 [collect_and_partition_mono_items] collect_and_partition_mono_items
end of query stack
error: aborting due to previous error

The text was updated successfully, but these errors were encountered:

jonas-schievink · 2020-05-06T19:02:51Z

Probably a duplicate of #62529

vcfxb · 2020-05-06T19:49:53Z

I'm guessing you might be right based on this part of the panic: (I expanded it for readability)

OutputTypeParameterMismatch(
    Binder(<[closure@ICE.rs:43:24: 43:40] as std::ops::FnOnce<(&<for<'a> fn(&'a str) -> (&'a str, &'a str) {main::bar} as Parser<'_>>::Output,)>>, 
    Binder(<[closure@ICE.rs:43:24: 43:40] as std::ops::FnOnce<(&&str,)>>), 
    Sorts(
        ExpectedFound { 
            expected: &str, 
            found: <for<'a> fn(&'a str) -> (&'a str, &'a str) {main::bar} as Parser<'_>>::Output 
        }
    )
)

rust-lang/rust#71955

jackh726 · 2021-08-26T12:33:56Z

No longer ICEs with #85499, but still errors and looks like it shouldn't. Keeping open to look into.

jonas-schievink added C-bug Category: This is a bug. I-ICE Issue: The compiler panicked, giving an Internal Compilation Error (ICE) ❄️ T-compiler Relevant to the compiler team, which will review and decide on the PR/issue. labels May 6, 2020

vcfxb mentioned this issue May 6, 2020

ICE rink: higher-rank trait bound (HRTB) for<'a> ... hits OutputTypeParameterMismatch in librustc/traits/codegen #62529

Closed

vcfxb added a commit to vcfxb/wright-lang that referenced this issue May 7, 2020

waiting on rust issue due to ICE

ea165c9

rust-lang/rust#71955

rust-lang-glacier-bot added the glacier ICE tracked in rust-lang/glacier. label May 7, 2020

github-actions bot mentioned this issue Aug 26, 2021

ices/71955.rs: fixed with errors rust-lang/glacier#923

Closed

jackh726 mentioned this issue Aug 28, 2021

Normalize obligations for closure confirmation #88441

Merged

bors closed this as completed in 18cae26 Nov 6, 2021

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[BUG REPORT]: Internal Compiler Error on stable surrounding type inference #71955

[BUG REPORT]: Internal Compiler Error on stable surrounding type inference #71955

vcfxb commented May 6, 2020

jonas-schievink commented May 6, 2020

vcfxb commented May 6, 2020 •

edited

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jackh726 commented Aug 26, 2021

[BUG REPORT]: Internal Compiler Error on stable surrounding type inference #71955

[BUG REPORT]: Internal Compiler Error on stable surrounding type inference #71955

Comments

vcfxb commented May 6, 2020

Code:

Expectaions:

Result

Meta

jonas-schievink commented May 6, 2020

vcfxb commented May 6, 2020 • edited Loading

jackh726 commented Aug 26, 2021

vcfxb commented May 6, 2020 •

edited

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