Closed
Description
In all honesty this code is a bit contrived and nonsensical. I just happen to run into this panic while coding. It seems to have something do with both the .iter() and match on u64::max_value().
I tried this code:
use std::slice::Iter;
#[derive(Clone, Copy)]
pub struct Word8([usize; 8]);
impl Word8 {
pub fn iter(&self) -> Iter<usize> {
self.0.iter()
}
}
fn bug(word: Word8) -> u64 {
word.iter().for_each(|wire| match 0 {
u64::max_value() => 0,
});
0
}
https://gist.github.com/4280b3c650ed29ba3645dc6f2a348ef5
I expected to see this happen: give me an error about why this is wrong.
Instead, this happened: got panic
Meta
rustc --version --verbose:
rustc 1.30.0-beta.17 (f33946f 2018-10-23)
binary: rustc
commit-hash: f33946f
commit-date: 2018-10-23
host: x86_64-unknown-linux-gnu
release: 1.30.0-beta.17
LLVM version: 8.0
Backtrace:
error[E0601]: `main` function not found in crate `tmp`
|
= note: consider adding a `main` function to `tmp.rs`
error[E0164]: expected tuple struct/variant, found method `<u64>::max_value`
--> tmp.rs:14:9
|
14 | u64::max_value() => 0,
| ^^^^^^^^^^^^^^^^ not a tuple variant or struct
error[E0308]: mismatched types
--> tmp.rs:13:33
|
13 | word.iter().for_each(|wire| match 0 {
| _________________________________^
14 | | u64::max_value() => 0,
15 | | });
| |_____^ expected (), found integral variable
|
= note: expected type `()`
found type `{integer}`
error: internal compiler error: librustc/middle/mem_categorization.rs:1302: tuple struct pattern didn't resolve to variant or struct Method(DefId(2/0:9137 ~ core[396f]::num[0]::{{impl}}[15]::max_value[0]))
--> tmp.rs:14:9
|
14 | u64::max_value() => 0,
| ^^^^^^^^^^^^^^^^
thread 'main' panicked at 'Box<Any>', librustc_errors/lib.rs:525:9
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
at libstd/sys_common/backtrace.rs:59
2: std::panicking::default_hook::{{closure}}
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:481
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::middle::mem_categorization::MemCategorizationContext::cat_pattern_
15: rustc::middle::expr_use_visitor::ExprUseVisitor::walk_expr
16: rustc::middle::expr_use_visitor::ExprUseVisitor::consume_expr
17: rustc_typeck::check::upvar::<impl rustc_typeck::check::FnCtxt<'a, 'gcx, 'tcx>>::analyze_closure
18: <rustc_typeck::check::upvar::InferBorrowKindVisitor<'a, 'gcx, 'tcx> as rustc::hir::intravisit::Visitor<'gcx>>::visit_expr
19: rustc::hir::intravisit::walk_expr
20: rustc::hir::intravisit::walk_expr
21: rustc::ty::context::tls::with_related_context
22: rustc::infer::InferCtxtBuilder::enter
23: rustc_typeck::check::typeck_tables_of
24: rustc::ty::query::__query_compute::typeck_tables_of
25: rustc::ty::query::<impl rustc::ty::query::config::QueryAccessors<'tcx> for rustc::ty::query::queries::typeck_tables_of<'tcx>>::compute
26: rustc::dep_graph::graph::DepGraph::with_task_impl
27: rustc::ty::context::tls::with_related_context
28: rustc::ty::query::plumbing::<impl rustc::ty::context::TyCtxt<'a, 'gcx, 'tcx>>::force_query_with_job
29: rustc::ty::query::plumbing::<impl rustc::ty::context::TyCtxt<'a, 'gcx, 'tcx>>::get_query
30: rustc::ty::query::plumbing::<impl rustc::ty::context::TyCtxt<'a, 'gcx, 'tcx>>::ensure_query
31: rustc_typeck::check::typeck_item_bodies
32: rustc::ty::query::<impl rustc::ty::query::config::QueryAccessors<'tcx> for rustc::ty::query::queries::typeck_item_bodies<'tcx>>::compute
33: rustc::dep_graph::graph::DepGraph::with_task_impl
34: rustc::ty::context::tls::with_related_context
35: rustc::ty::query::plumbing::<impl rustc::ty::context::TyCtxt<'a, 'gcx, 'tcx>>::force_query_with_job
36: rustc::ty::query::plumbing::<impl rustc::ty::context::TyCtxt<'a, 'gcx, 'tcx>>::get_query
37: rustc_typeck::check_crate
38: rustc::ty::context::tls::enter_context
39: <std::thread::local::LocalKey<T>>::with
40: rustc::ty::context::TyCtxt::create_and_enter
41: rustc_driver::driver::compile_input
42: rustc_driver::run_compiler_with_pool
43: rustc_driver::driver::spawn_thread_pool
44: rustc_driver::run_compiler
45: <scoped_tls::ScopedKey<T>>::set
46: syntax::with_globals
47: __rust_maybe_catch_panic
at libpanic_unwind/lib.rs:103
48: rustc_driver::run
49: rustc_driver::main
50: std::rt::lang_start::{{closure}}
51: std::panicking::try::do_call
at libstd/rt.rs:59
at libstd/panicking.rs:310
52: __rust_maybe_catch_panic
at libpanic_unwind/lib.rs:103
53: std::rt::lang_start_internal
at libstd/panicking.rs:289
at libstd/panic.rs:392
at libstd/rt.rs:58
54: main
55: __libc_start_main
56: <unknown>
query stack during panic:
#0 [typeck_tables_of] processing `bug`
#1 [typeck_item_bodies] type-checking all item bodies
end of query stack
error: aborting due to 4 previous errors
Some errors occurred: E0164, E0308, E0601.
For more information about an error, try `rustc --explain E0164`.
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 1.30.0-beta.17 (f33946f81 2018-10-23) running on x86_64-unknown-linux-gnu