ICE on Beta when matching on not a tuple variant or struct

[moxian]

The following code on latest beta (rustc 1.31.0-beta.17 (1a4f1f3 2018-11-25))

use std::ffi::OsStr;

fn foo() {
    match Some(OsStr::new("1")) {
        Some(OsStr::new("2")) => (),
    }
}

results in ICE

backtrace

thread 'main' panicked at 'expected fn type', libcore\option.rs:1008:5
stack backtrace:
   0: <std::sync::mpsc::select::Select as core::fmt::Debug>::fmt
   1: <std::path::Iter<'a> as core::convert::AsRef<std::path::Path>>::as_ref
   2: std::panicking::take_hook
   3: std::panicking::take_hook
   4: <rustc::ty::sty::Binder<rustc::ty::ProjectionPredicate<'tcx>> as rustc::ty
::ToPredicate<'tcx>>::to_predicate
   5: std::panicking::rust_panic_with_hook
   6: std::panicking::begin_panic_fmt
   7: rust_begin_unwind
   8: core::panicking::panic_fmt
   9: core::option::expect_failed
  10: <unknown>
  11: <unknown>
  12: <unknown>
  13: <unknown>
  14: <rustc_typeck::outlives::implicit_infer::IgnoreSelfTy as core::fmt::Debug>
::fmt
  15: <rustc_typeck::check::method::suggest::TraitInfo as core::cmp::PartialOrd>
::partial_cmp
  16: <rustc_typeck::check::FnCtxt<'a, 'gcx, 'tcx> as rustc_typeck::astconv::Ast
Conv<'gcx, 'tcx>>::record_ty
  17: <rustc_typeck::check::FnCtxt<'a, 'gcx, 'tcx> as rustc_typeck::astconv::Ast
Conv<'gcx, 'tcx>>::record_ty
  18: <rustc_typeck::check::FnCtxt<'a, 'gcx, 'tcx> as rustc_typeck::astconv::Ast
Conv<'gcx, 'tcx>>::record_ty
  19: <rustc_typeck::check::FnCtxt<'a, 'gcx, 'tcx> as rustc_typeck::astconv::Ast
Conv<'gcx, 'tcx>>::record_ty
  20: <rustc_typeck::check::FnCtxt<'a, 'gcx, 'tcx> as rustc_typeck::astconv::Ast
Conv<'gcx, 'tcx>>::record_ty
  21: <rustc_typeck::check::FnCtxt<'a, 'gcx, 'tcx> as rustc_typeck::astconv::Ast
Conv<'gcx, 'tcx>>::record_ty
  22: <rustc_typeck::check::GatherLocalsVisitor<'a, 'gcx, 'tcx> as rustc::hir::i
ntravisit::Visitor<'gcx>>::visit_pat
  23: <rustc_typeck::outlives::explicit::ExplicitPredicatesMap<'tcx> as core::fm
t::Debug>::fmt
  24: <rustc_typeck::check::method::probe::ProbeScope as core::fmt::Debug>::fmt
  25: <rustc_typeck::check::CheckItemTypesVisitor<'a, 'tcx> as rustc::hir::iteml
ikevisit::ItemLikeVisitor<'tcx>>::visit_item
  26: <rustc::traits::query::outlives_bounds::OutlivesBound<'a> as rustc::ty::co
ntext::Lift<'tcx>>::lift_to_tcx
  27: <rustc::traits::query::outlives_bounds::OutlivesBound<'a> as rustc::ty::co
ntext::Lift<'tcx>>::lift_to_tcx
  28: rustc::ty::context::tls::track_diagnostic
  29: rustc::dep_graph::graph::DepGraph::assert_ignored
  30: rustc::ty::adjustment::<impl core::convert::From<rustc::ty::adjustment::Au
toBorrowMutability> for rustc::hir::Mutability>::from
  31: rustc::ty::query::plumbing::<impl rustc::ty::context::TyCtxt<'a, 'gcx, 'tc
x>>::try_print_query_stack
  32: rustc::ty::query::plumbing::<impl rustc::ty::context::TyCtxt<'a, 'gcx, 'tc
x>>::try_print_query_stack
  33: rustc::ty::query::plumbing::<impl rustc::ty::context::TyCtxt<'a, 'gcx, 'tc
x>>::try_print_query_stack
  34: <rustc_typeck::check::PathSeg as core::fmt::Debug>::fmt
  35: <rustc_typeck::check::CheckItemTypesVisitor<'a, 'tcx> as rustc::hir::iteml
ikevisit::ItemLikeVisitor<'tcx>>::visit_item
  36: <rustc::traits::query::outlives_bounds::OutlivesBound<'a> as rustc::ty::co
ntext::Lift<'tcx>>::lift_to_tcx
  37: rustc::ty::context::tls::track_diagnostic
  38: rustc::dep_graph::graph::DepGraph::assert_ignored
  39: rustc::ty::adjustment::<impl core::convert::From<rustc::ty::adjustment::Au
toBorrowMutability> for rustc::hir::Mutability>::from
  40: rustc::ty::query::plumbing::<impl rustc::ty::context::TyCtxt<'a, 'gcx, 'tc
x>>::try_print_query_stack
  41: rustc::ty::query::plumbing::<impl rustc::ty::context::TyCtxt<'a, 'gcx, 'tc
x>>::try_print_query_stack
  42: rustc_typeck::check_crate
  43: <rustc_driver::pretty::IdentifiedAnnotation<'hir> as rustc_driver::pretty:
:HirPrinterSupport<'hir>>::sess
  44: <rustc_driver::pretty::IdentifiedAnnotation<'hir> as rustc_driver::pretty:
:HirPrinterSupport<'hir>>::sess
  45: <rustc_driver::pretty::IdentifiedAnnotation<'hir> as rustc_driver::pretty:
:HirPrinterSupport<'hir>>::sess
  46: rustc_driver::driver::compile_input
  47: rustc_driver::run_compiler
  48: <rustc_driver::profile::trace::Query as core::fmt::Debug>::fmt
  49: rustc_driver::run_compiler
  50: <rustc_driver::profile::trace::Query as core::fmt::Debug>::fmt
  51: _rust_maybe_catch_panic
  52: <env_logger::filter::inner::Filter as core::fmt::Display>::fmt
  53: rustc_driver::main
  54: <unknown>
  55: std::panicking::update_panic_count
  56: _rust_maybe_catch_panic
  57: std::rt::lang_start_internal
  58: <unknown>
  59: <unknown>
  60: BaseThreadInitThunk
  61: RtlUserThreadStart
query stack during panic:
#0 [typeck_tables_of] processing `foo`
#1 [typeck_item_bodies] type-checking all item bodies
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/m
aster/CONTRIBUTING.md#bug-reports

note: rustc 1.31.0-beta.17 (1a4f1f398 2018-11-25) running on x86_64-pc-windows-m
svc

note: compiler flags: -C debuginfo=2 -C incremental --crate-type lib

note: some of the compiler flags provided by cargo are hidden

error: Could not compile `osstring`.

To learn more, run the command again with --verbose.

Latest nightly (rustc 1.32.0-nightly (6acbb5b 2018-11-25)) does not result in ICE.

error[E0164]: expected tuple struct/variant, found method `<OsStr>::new`
 --> src\lib.rs:5:14
  |
5 |         Some(OsStr::new("2")) => (),
  |              ^^^^^^^^^^^^^^^ not a tuple variant or struct

error: aborting due to previous error

For more information about this error, try `rustc --explain E0164`.
error: Could not compile `osstring`.

To learn more, run the command again with --verbose.

I would guess whatever fix there was in nightly should be backported to beta/stable as well.

P.s: is not a problem on 1.29.0 stable. Is a problem on 1.30.1

[oli-obk]

I'm guessing #55742 needs a backport

[moxian]

Re:tags: This is a regression both from stable to beta and from stable to stable. IOW, the bug is present in current 1.30.1 stable (but was not in 1.29.0).

[nikomatsakis]

@oli-obk that PR appears to have been included in #55803, no?

[oli-obk]

Not sure I understand. #55803 is a rollup PR that merged #55742, true, but I don't see how the rollup relates to this issue.

[nikomatsakis]

@oli-obk I'm just confused why that PR is not already backported to beta. But I agree it is not (was just checking).

[nikomatsakis]

Oh, sorry, I was reading #55803 was "beta backport rollup", but it's just an ordinary rollup. OK.

[nikomatsakis]

Created #56240 with a backport

[petrochenkov]

Fixed in #56240