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"failed to normalize" ICE in NLL borrow checker #61311
Description
Happens on stable 1.34.2, 1.35.0 and current nightly (2019-05-28). Playground.
pub trait IntoFuture {
type Item;
type Error;
type Future: Future<Item=Self::Item, Error=Self::Error>;
}
impl<T, E> IntoFuture for Result<T, E> {
type Item = T;
type Error = E;
type Future = Fut<T, E>;
}
pub trait Future {
type Item;
type Error;
}
struct Fut<T, E>(T, E);
impl<T, E> Future for Fut<T, E> {
type Item = T;
type Error = E;
}
type BoxedError = Box<dyn std::error::Error + Send + Sync>;
trait FromRequest {
type Context;
fn from_request(context: Self::Context);
}
trait Guard {
type Result;
}
struct Authenticated<R> {
inner: R,
}
impl<R> FromRequest for Authenticated<R>
where
<User as Guard>::Result:
IntoFuture<Item = User, Error = BoxedError>,
<<User as Guard>::Result as IntoFuture>::Future:
Send,
{
type Context = ();
fn from_request(_: Self::Context) {}
}
struct User;
impl Guard for User {
type Result = Result<Self, BoxedError>;
}Results in:
error: internal compiler error: src/librustc_mir/borrow_check/nll/type_check/free_region_relations.rs:260: failed to normalize <Authenticated<R> as FromRequest>::Context
thread 'rustc' panicked at 'Box<Any>', src/librustc_errors/lib.rs:637:9
stack backtrace:
0: backtrace::backtrace::libunwind::trace
at /cargo/registry/src/github.com-1ecc6299db9ec823/backtrace-0.3.25/src/backtrace/libunwind.rs:97
1: backtrace::backtrace::trace_unsynchronized
at /cargo/registry/src/github.com-1ecc6299db9ec823/backtrace-0.3.25/src/backtrace/mod.rs:66
2: std::sys_common::backtrace::_print
at src/libstd/sys_common/backtrace.rs:47
3: std::sys_common::backtrace::print
at src/libstd/sys_common/backtrace.rs:36
4: std::panicking::default_hook::{{closure}}
at src/libstd/panicking.rs:197
5: std::panicking::default_hook
at src/libstd/panicking.rs:211
6: rustc::util::common::panic_hook
7: std::panicking::rust_panic_with_hook
at src/libstd/panicking.rs:478
8: std::panicking::begin_panic
9: rustc_errors::Handler::bug
10: rustc::util::bug::opt_span_bug_fmt::{{closure}}
11: rustc::ty::context::tls::with_opt::{{closure}}
12: rustc::ty::context::tls::with_context_opt
13: rustc::ty::context::tls::with_opt
14: rustc::util::bug::opt_span_bug_fmt
15: rustc::util::bug::bug_fmt
16: core::ops::function::impls::<impl core::ops::function::FnOnce<A> for &mut F>::call_once
17: <core::iter::adapters::flatten::FlatMap<I,U,F> as core::iter::traits::iterator::Iterator>::next
18: <alloc::vec::Vec<T> as alloc::vec::SpecExtend<T,I>>::from_iter
19: rustc_mir::borrow_check::nll::type_check::free_region_relations::create
20: rustc_mir::borrow_check::nll::type_check::type_check
21: rustc_mir::borrow_check::nll::compute_regions
22: rustc_mir::borrow_check::do_mir_borrowck
23: rustc::ty::context::GlobalCtxt::enter_local
24: rustc_mir::borrow_check::mir_borrowck
25: rustc::ty::query::__query_compute::mir_borrowck
26: rustc::ty::query::<impl rustc::ty::query::config::QueryAccessors for rustc::ty::query::queries::mir_borrowck>::compute
27: rustc::dep_graph::graph::DepGraph::with_task_impl
28: rustc::ty::query::plumbing::<impl rustc::ty::context::TyCtxt>::get_query
29: rustc::ty::<impl rustc::ty::context::TyCtxt>::par_body_owners
30: rustc::util::common::time
31: rustc_interface::passes::analysis
32: rustc::ty::query::__query_compute::analysis
33: rustc::dep_graph::graph::DepGraph::with_task_impl
34: rustc::ty::query::plumbing::<impl rustc::ty::context::TyCtxt>::get_query
35: rustc::ty::context::tls::enter_global
36: rustc_interface::passes::BoxedGlobalCtxt::access::{{closure}}
37: rustc_interface::passes::create_global_ctxt::{{closure}}
38: rustc_interface::interface::run_compiler_in_existing_thread_pool
39: std::thread::local::LocalKey<T>::with
40: scoped_tls::ScopedKey<T>::set
41: syntax::with_globals
note: Some details are omitted, run with `RUST_BACKTRACE=full` for a verbose backtrace.
query stack during panic:
#0 [mir_borrowck] processing `<Authenticated<R> as FromRequest>::from_request`
#1 [analysis] running analysis passes on this crate
end of query stack
error: aborting due to previous error
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 1.37.0-nightly (721268583 2019-05-28) running on x86_64-unknown-linux-gnu
note: compiler flags: -C codegen-units=1 -C debuginfo=2 --crate-type lib
note: some of the compiler flags provided by cargo are hidden
Activity
Centril commentedon May 29, 2019
Reduced:
Centril commentedon May 29, 2019
Compiles fine on 1.34.0; haven't tested 1.34.1.
jonas-schievink commentedon May 29, 2019
@Centril both my repro and your reduced one do ICE on
rustc 1.34.0 (91856ed52 2019-04-10)(andrustc 1.34.1 (fc50f328b 2019-04-24)) for me, can you verify that again?jonas-schievink commentedon May 29, 2019
Happens all the way back to 1.30.0 (with
RUSTC_BOOTSTRAP=1) for me, as long as--edition=2018is passed to rustc.Centril commentedon May 29, 2019
@jonas-schievink Ah of course!
--edition=2018is needed for NLL on older versions... :) I forgot that godbolt doesn't have that by default.Rollup merge of rust-lang#61488 - matthewjasper:fix-nll-typeck-ices, …
Rollup merge of rust-lang#61488 - matthewjasper:fix-nll-typeck-ices, …