Closed
Description
The following ICE's on nightly 2018:
#![feature(generators, generator_trait)]
use std::ops::Generator;
use std::ops::GeneratorState::Yielded;
pub struct GenIter<G>(G);
impl <G> Iterator for GenIter<G>
where
G: Generator,
{
type Item = G::Yield;
fn next(&mut self) -> Option<Self::Item> {
unsafe {
match self.0.resume() {
Yielded(y) => Some(y),
_ => None
}
}
}
}
fn bug<'a>() -> impl Iterator<Item = &'a str> {
GenIter(move || {
let mut s = String::new();
yield &s[..]
})
}
fn main() {
bug();
}This is an NLL issue, on 2015 nightly without NLL turned on, the compiler complains that s does not live long enough. with NLL turned on in 2015, I get the same ICE.
Backtrace:
error: internal compiler error: librustc_mir/borrow_check/nll/region_infer/error_reporting/region_name.rs:181: can't make a name for free region '_#2r
--> src/main.rs:25:13
|
25 | GenIter(move || {
| _____________^
26 | | let mut s = String::new();
27 | | yield &s[..]
28 | | })
| |_____^
thread 'main' panicked at 'Box<Any>', librustc_errors/lib.rs:538:9
stack backtrace:
0: std::sys::unix::backtrace::tracing::imp::unwind_backtrace
at libstd/sys/unix/backtrace/tracing/gcc_s.rs:49
1: std::sys_common::backtrace::_print
at libstd/sys_common/backtrace.rs:71
2: std::panicking::default_hook::{{closure}}
at libstd/sys_common/backtrace.rs:59
at libstd/panicking.rs:211
3: std::panicking::default_hook
at libstd/panicking.rs:227
4: rustc::util::common::panic_hook
5: std::panicking::rust_panic_with_hook
at libstd/panicking.rs:480
6: std::panicking::begin_panic
7: rustc_errors::Handler::span_bug
8: rustc::util::bug::opt_span_bug_fmt::{{closure}}
9: rustc::ty::context::tls::with_opt::{{closure}}
10: rustc::ty::context::tls::with_context_opt
11: rustc::ty::context::tls::with_opt
12: rustc::util::bug::opt_span_bug_fmt
13: rustc::util::bug::span_bug_fmt
14: rustc_mir::borrow_check::nll::region_infer::error_reporting::region_name::<impl rustc_mir::borrow_check::nll::region_infer::RegionInferenceContext<'tcx>>::give_region_a_name
15: rustc_mir::borrow_check::nll::region_infer::error_reporting::<impl rustc_mir::borrow_check::nll::region_infer::RegionInferenceContext<'tcx>>::free_region_constraint_info
16: rustc_mir::borrow_check::nll::explain_borrow::<impl rustc_mir::borrow_check::MirBorrowckCtxt<'cx, 'gcx, 'tcx>>::explain_why_borrow_contains_point
17: rustc_mir::borrow_check::error_reporting::<impl rustc_mir::borrow_check::MirBorrowckCtxt<'cx, 'gcx, 'tcx>>::report_borrowed_value_does_not_live_long_enough
18: rustc_mir::borrow_check::path_utils::each_borrow_involving_path
19: rustc_mir::borrow_check::MirBorrowckCtxt::access_place
20: <rustc_mir::borrow_check::MirBorrowckCtxt<'cx, 'gcx, 'tcx> as rustc_mir::dataflow::DataflowResultsConsumer<'cx, 'tcx>>::visit_terminator_entry
21: rustc_mir::borrow_check::do_mir_borrowck
22: rustc::ty::context::tls::with_related_context
23: rustc::infer::InferCtxtBuilder::enter
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<'tcx> for rustc::ty::query::queries::mir_borrowck<'tcx>>::compute
27: rustc::dep_graph::graph::DepGraph::with_task_impl
28: rustc::ty::context::tls::with_related_context
29: rustc::ty::query::plumbing::<impl rustc::ty::context::TyCtxt<'a, 'gcx, 'tcx>>::force_query_with_job
30: rustc::ty::query::plumbing::<impl rustc::ty::context::TyCtxt<'a, 'gcx, 'tcx>>::get_query
31: rustc::ty::query::<impl rustc::ty::context::TyCtxt<'a, 'tcx, 'lcx>>::mir_borrowck
32: rustc_mir::borrow_check::nll::type_check::TypeChecker::check_stmt
33: rustc_mir::borrow_check::nll::type_check::TypeChecker::typeck_mir
34: rustc_mir::borrow_check::nll::type_check::type_check
35: rustc_mir::borrow_check::do_mir_borrowck
36: rustc::ty::context::tls::with_related_context
37: rustc::infer::InferCtxtBuilder::enter
38: rustc_mir::borrow_check::mir_borrowck
39: rustc::ty::query::__query_compute::mir_borrowck
40: rustc::ty::query::<impl rustc::ty::query::config::QueryAccessors<'tcx> for rustc::ty::query::queries::mir_borrowck<'tcx>>::compute
41: rustc::dep_graph::graph::DepGraph::with_task_impl
42: rustc::ty::context::tls::with_related_context
43: rustc::ty::query::plumbing::<impl rustc::ty::context::TyCtxt<'a, 'gcx, 'tcx>>::force_query_with_job
44: rustc::ty::query::plumbing::<impl rustc::ty::context::TyCtxt<'a, 'gcx, 'tcx>>::get_query
45: rustc::ty::query::<impl rustc::ty::context::TyCtxt<'a, 'tcx, 'lcx>>::mir_borrowck
46: rustc::ty::<impl rustc::ty::context::TyCtxt<'a, 'gcx, 'tcx>>::par_body_owners
47: rustc::util::common::time
48: rustc::ty::context::tls::enter_context
49: <std::thread::local::LocalKey<T>>::with
50: rustc::ty::context::TyCtxt::create_and_enter
51: rustc_driver::driver::compile_input
52: rustc_driver::run_compiler_with_pool
53: <scoped_tls::ScopedKey<T>>::set
54: rustc_driver::run_compiler
55: syntax::with_globals
56: __rust_maybe_catch_panic
at libpanic_unwind/lib.rs:102
57: rustc_driver::run
58: rustc_driver::main
59: std::rt::lang_start::{{closure}}
60: std::panicking::try::do_call
at libstd/rt.rs:59
at libstd/panicking.rs:310
61: __rust_maybe_catch_panic
at libpanic_unwind/lib.rs:102
62: std::rt::lang_start_internal
at libstd/panicking.rs:289
at libstd/panic.rs:398
at libstd/rt.rs:58
63: main
64: __libc_start_main
65: <unknown>
query stack during panic:
#0 [mir_borrowck] processing `bug::{{closure}}`
#1 [mir_borrowck] processing `bug`
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 1.32.0-nightly (36a50c29f 2018-11-09) running on x86_64-unknown-linux-gnu
note: compiler flags: -C opt-level=3 -C codegen-units=1 --crate-type bin
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.