Closed
Description
openedon Mar 3, 2019
#![feature(existential_type)]
trait UnwrapItemsExt {
type II;
fn unwrap_items(self) -> Self::II;
}
impl<I, T, E> UnwrapItemsExt for I
where
I: Iterator<Item = Result<T, E>>,
E: std::fmt::Debug,
{
existential type II: Iterator<Item = T>;
fn unwrap_items(self) -> Self::II {
self.map(|x| x.unwrap())
}
} Compiling playground v0.0.1 (/playground)
thread 'rustc' panicked at 'called `Option::unwrap()` on a `None` value', src/libcore/option.rs:345:21
stack backtrace:
0: std::sys::unix::backtrace::tracing::imp::unwind_backtrace
at src/libstd/sys/unix/backtrace/tracing/gcc_s.rs:39
1: std::sys_common::backtrace::_print
at src/libstd/sys_common/backtrace.rs:71
2: std::panicking::default_hook::{{closure}}
at src/libstd/sys_common/backtrace.rs:59
at src/libstd/panicking.rs:200
3: std::panicking::default_hook
at src/libstd/panicking.rs:215
4: rustc::util::common::panic_hook
5: std::panicking::rust_panic_with_hook
at src/libstd/panicking.rs:482
6: std::panicking::continue_panic_fmt
at src/libstd/panicking.rs:385
7: rust_begin_unwind
at src/libstd/panicking.rs:312
8: core::panicking::panic_fmt
at src/libcore/panicking.rs:85
9: core::panicking::panic
at src/libcore/panicking.rs:49
10: rustc_typeck::check::writeback::WritebackCx::visit_opaque_types
11: rustc_typeck::check::writeback::<impl rustc_typeck::check::FnCtxt<'a, 'gcx, 'tcx>>::resolve_type_vars_in_body
12: rustc::ty::context::GlobalCtxt::enter_local
13: rustc_typeck::check::typeck_tables_of
14: rustc::ty::query::__query_compute::typeck_tables_of
15: rustc::ty::query::<impl rustc::ty::query::config::QueryAccessors<'tcx> for rustc::ty::query::queries::typeck_tables_of<'tcx>>::compute
16: rustc::dep_graph::graph::DepGraph::with_task_impl
17: rustc::ty::query::plumbing::<impl rustc::ty::context::TyCtxt<'a, 'gcx, 'tcx>>::get_query
18: rustc_typeck::collect::find_existential_constraints::ConstraintLocator::check
19: rustc::hir::intravisit::Visitor::visit_nested_impl_item
20: rustc::hir::intravisit::walk_item
21: rustc_typeck::collect::find_existential_constraints
22: rustc_typeck::collect::type_of
23: rustc::ty::query::__query_compute::type_of
24: rustc::ty::query::<impl rustc::ty::query::config::QueryAccessors<'tcx> for rustc::ty::query::queries::type_of<'tcx>>::compute
25: rustc::dep_graph::graph::DepGraph::with_task_impl
26: rustc::ty::query::plumbing::<impl rustc::ty::context::TyCtxt<'a, 'gcx, 'tcx>>::get_query
27: <rustc_typeck::collect::CollectItemTypesVisitor<'a, 'tcx> as rustc::hir::intravisit::Visitor<'tcx>>::visit_impl_item
28: rustc::hir::map::Map::visit_item_likes_in_module
29: rustc_typeck::collect::collect_mod_item_types
30: rustc::ty::query::__query_compute::collect_mod_item_types
31: rustc::ty::query::<impl rustc::ty::query::config::QueryAccessors<'tcx> for rustc::ty::query::queries::collect_mod_item_types<'tcx>>::compute
32: rustc::dep_graph::graph::DepGraph::with_task_impl
33: rustc::ty::query::plumbing::<impl rustc::ty::context::TyCtxt<'a, 'gcx, 'tcx>>::get_query
34: rustc_typeck::collect::collect_item_types
35: rustc::util::common::time
36: rustc_typeck::check_crate
37: rustc_interface::passes::analysis
38: rustc::ty::query::__query_compute::analysis
39: rustc::ty::query::<impl rustc::ty::query::config::QueryAccessors<'tcx> for rustc::ty::query::queries::analysis<'tcx>>::compute
40: rustc::dep_graph::graph::DepGraph::with_task_impl
41: rustc::ty::query::plumbing::<impl rustc::ty::context::TyCtxt<'a, 'gcx, 'tcx>>::get_query
42: <std::thread::local::LocalKey<T>>::with
43: rustc::ty::context::TyCtxt::create_and_enter
44: rustc_driver::driver::compile_input
45: <scoped_tls::ScopedKey<T>>::set
46: rustc_driver::run_compiler
47: <scoped_tls::ScopedKey<T>>::set
48: syntax::with_globals
49: __rust_maybe_catch_panic
at src/libpanic_unwind/lib.rs:87
50: <F as alloc::boxed::FnBox<A>>::call_box
51: std::sys::unix::thread::Thread::new::thread_start
at /rustc/0ea22717a1e01fa535534b85a5347a7e49fc79de/src/liballoc/boxed.rs:759
at src/libstd/sys_common/thread.rs:14
at src/libstd/sys/unix/thread.rs:80
52: start_thread
53: __clone
query stack during panic:
#0 [typeck_tables_of] processing `<I as UnwrapItemsExt>::unwrap_items`
#1 [type_of] processing `<I as UnwrapItemsExt>::II`
#2 [collect_mod_item_types] collecting item types in top-level module
#3 [analysis] running analysis passes on this crate
end of query stack
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 1.34.0-nightly (0ea22717a 2019-03-02) 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
error: Could not compile `playground`.
To learn more, run the command again with --verbose.
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Area: `impl Trait`. Universally / existentially quantified anonymous types with static dispatch.Call for participation: Easy difficulty. Experience needed to fix: Not much. Good first issue.Call for participation: An issue has been fixed and does not reproduce, but no test has been added.Issue: The compiler panicked, giving an Internal Compilation Error (ICE) ❄️Relevant to the compiler team, which will review and decide on the PR/issue.