Open
Description
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:
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