ICE When initializing a struct with update syntax in closure

[dlrobertson]

TL;DR

When initializing a struct with update syntax inside a closure, an ICE occurs if a nonexistent or misspelled member is listed.

Example that Triggers ICE

struct Point {
    pub x: u64,
    pub y: u64,
}

const TEMPLATE: Point = Point {
    x: 0,
    y: 0
};

fn main() {
    let x = || {
        Point {
            nonexistent: 0,
            ..TEMPLATE
        }
    };
}

Backtrace

thread 'main' panicked at 'no index for a field', libcore/option.rs:914:5
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
             at librustc/util/common.rs:54
   5: std::panicking::rust_panic_with_hook
             at libstd/panicking.rs:467
   6: std::panicking::begin_panic_fmt
             at libstd/panicking.rs:350
   7: rust_begin_unwind
             at libstd/panicking.rs:328
   8: core::panicking::panic_fmt
             at libcore/panicking.rs:71
   9: core::option::expect_failed
             at libcore/option.rs:914
  10: rustc::ty::<impl rustc::ty::context::TyCtxt<'a, 'gcx, 'tcx>>::field_index
             at /home/drobertson/git/rust/src/libcore/option.rs:302
             at librustc/ty/mod.rs:2410
  11: rustc::middle::expr_use_visitor::ExprUseVisitor::walk_expr
             at librustc/middle/expr_use_visitor.rs:665
             at /home/drobertson/git/rust/src/libcore/iter/iterator.rs:1689
             at /home/drobertson/git/rust/src/libcore/iter/iterator.rs:1519
             at /home/drobertson/git/rust/src/libcore/slice/mod.rs:2693
             at /home/drobertson/git/rust/src/libcore/iter/iterator.rs:1519
             at /home/drobertson/git/rust/src/libcore/iter/iterator.rs:1688
             at librustc/middle/expr_use_visitor.rs:664
             at librustc/middle/expr_use_visitor.rs:423
  12: rustc::middle::expr_use_visitor::ExprUseVisitor::consume_expr
             at librustc/middle/expr_use_visitor.rs:358
  13: rustc::middle::expr_use_visitor::ExprUseVisitor::walk_block
             at librustc/middle/expr_use_visitor.rs:639
  14: rustc::middle::expr_use_visitor::ExprUseVisitor::walk_expr
             at librustc/middle/expr_use_visitor.rs:0
  15: rustc::middle::expr_use_visitor::ExprUseVisitor::consume_expr
             at librustc/middle/expr_use_visitor.rs:358
  16: rustc::middle::expr_use_visitor::ExprUseVisitor::consume_body
             at librustc/middle/expr_use_visitor.rs:329
  17: rustc_typeck::check::upvar::<impl rustc_typeck::check::FnCtxt<'a, 'gcx, 'tcx>>::analyze_closure
             at librustc_typeck/check/upvar.rs:171
  18: <rustc_typeck::check::upvar::InferBorrowKindVisitor<'a, 'gcx, 'tcx> as rustc::hir::intravisit::Visitor<'gcx>>::visit_expr
             at librustc_typeck/check/upvar.rs:80
  19: rustc::hir::intravisit::walk_local
             at /home/drobertson/git/rust/src/<walk_list macros>:2
  20: rustc::hir::intravisit::walk_block
             at /home/drobertson/git/rust/src/<walk_list macros>:2
  21: rustc_typeck::check::upvar::<impl rustc_typeck::check::FnCtxt<'a, 'gcx, 'tcx>>::closure_analyze                                                                                                                                 
             at librustc_typeck/check/upvar.rs:59
  22: rustc::ty::context::tls::with_related_context
             at librustc_typeck/check/mod.rs:904
             at librustc_typeck/check/mod.rs:617
             at /home/drobertson/git/rust/src/librustc/infer/mod.rs:453
             at /home/drobertson/git/rust/src/librustc/ty/context.rs:1578
             at /home/drobertson/git/rust/src/librustc/ty/context.rs:1844
             at /home/drobertson/git/rust/src/librustc/ty/context.rs:1787
             at /home/drobertson/git/rust/src/librustc/ty/context.rs:1843
             at /home/drobertson/git/rust/src/librustc/ty/context.rs:1577
             at /home/drobertson/git/rust/src/librustc/ty/context.rs:1905
             at /home/drobertson/git/rust/src/librustc/ty/context.rs:1889
             at /home/drobertson/git/rust/src/librustc/ty/context.rs:1880
             at /home/drobertson/git/rust/src/librustc/ty/context.rs:1889
             at /home/drobertson/git/rust/src/librustc/ty/context.rs:1900
  23: rustc::ty::context::GlobalCtxt::enter_local
             at /home/drobertson/git/rust/src/librustc/ty/context.rs:1570
  24: rustc::infer::InferCtxtBuilder::enter
             at /home/drobertson/git/rust/src/librustc/infer/mod.rs:453
  25: rustc_typeck::check::InheritedBuilder::enter
             at librustc_typeck/check/mod.rs:617
  26: rustc_typeck::check::typeck_tables_of
             at librustc_typeck/check/mod.rs:855
  27: rustc::ty::maps::<impl rustc::ty::maps::config::QueryConfig<'tcx> for rustc::ty::maps::queries::typeck_tables_of<'tcx>>::compute
             at librustc/ty/maps/plumbing.rs:723
  28: rustc::dep_graph::graph::DepGraph::with_task_impl
             at librustc/dep_graph/graph.rs:343
  29: rustc::dep_graph::graph::DepGraph::with_task
             at librustc/dep_graph/graph.rs:209
  30: rustc::ty::context::tls::with_related_context
             at librustc/ty/maps/plumbing.rs:530
             at librustc/ty/maps/plumbing.rs:200
             at librustc/ty/context.rs:1844
             at librustc/ty/context.rs:1787
             at librustc/ty/context.rs:1843
             at librustc/ty/maps/plumbing.rs:199
             at librustc/ty/context.rs:1905
             at librustc/ty/context.rs:1889
             at librustc/ty/context.rs:1880
             at librustc/ty/context.rs:1889
             at librustc/ty/context.rs:1900
  31: <rustc::ty::maps::plumbing::JobOwner<'a, 'tcx, Q>>::start
             at librustc/ty/maps/plumbing.rs:189
  32: rustc::ty::maps::plumbing::<impl rustc::ty::context::TyCtxt<'a, 'gcx, 'tcx>>::force_query_with_job
             at librustc/ty/maps/plumbing.rs:523
  33: rustc::ty::maps::plumbing::<impl rustc::ty::context::TyCtxt<'a, 'gcx, 'tcx>>::get_query
             at librustc/ty/maps/plumbing.rs:372
             at librustc/ty/maps/plumbing.rs:599
             at librustc/ty/maps/plumbing.rs:606
  34: rustc::ty::maps::plumbing::<impl rustc::ty::context::TyCtxt<'a, 'gcx, 'tcx>>::ensure_query
             at librustc/ty/maps/plumbing.rs:574
  35: rustc::session::Session::track_errors
             at librustc_typeck/check/mod.rs:715
             at /home/drobertson/git/rust/src/librustc/session/mod.rs:318
  36: rustc_typeck::check::typeck_item_bodies
             at librustc_typeck/check/mod.rs:713
  37: rustc::ty::maps::<impl rustc::ty::maps::config::QueryConfig<'tcx> for rustc::ty::maps::queries::typeck_item_bodies<'tcx>>::compute
             at librustc/ty/maps/plumbing.rs:723
  38: rustc::dep_graph::graph::DepGraph::with_task_impl
             at librustc/dep_graph/graph.rs:343
  39: rustc::dep_graph::graph::DepGraph::with_task
             at librustc/dep_graph/graph.rs:209
  40: rustc::ty::context::tls::with_related_context
             at librustc/ty/maps/plumbing.rs:530
             at librustc/ty/maps/plumbing.rs:200
             at librustc/ty/context.rs:1844
             at librustc/ty/context.rs:1787
             at librustc/ty/context.rs:1843
             at librustc/ty/maps/plumbing.rs:199
             at librustc/ty/context.rs:1905
             at librustc/ty/context.rs:1889
             at librustc/ty/context.rs:1880
             at librustc/ty/context.rs:1889
             at librustc/ty/context.rs:1900
  41: <rustc::ty::maps::plumbing::JobOwner<'a, 'tcx, Q>>::start
             at librustc/ty/maps/plumbing.rs:189
  42: rustc::ty::maps::plumbing::<impl rustc::ty::context::TyCtxt<'a, 'gcx, 'tcx>>::force_query_with_job
             at librustc/ty/maps/plumbing.rs:523
  43: rustc::ty::maps::plumbing::<impl rustc::ty::context::TyCtxt<'a, 'gcx, 'tcx>>::get_query
             at librustc/ty/maps/plumbing.rs:372
             at librustc/ty/maps/plumbing.rs:599
             at librustc/ty/maps/plumbing.rs:606
  44: rustc::ty::maps::<impl rustc::ty::context::TyCtxt<'a, 'tcx, 'lcx>>::typeck_item_bodies
             at librustc/ty/maps/plumbing.rs:769
  45: rustc::util::common::time
             at librustc_typeck/lib.rs:344
             at /home/drobertson/git/rust/src/librustc/util/common.rs:166
             at /home/drobertson/git/rust/src/librustc/util/common.rs:160
  46: rustc_typeck::check_crate
             at librustc_typeck/lib.rs:344
  47: rustc::ty::context::tls::enter_context
             at librustc_driver/driver.rs:1121
             at /home/drobertson/git/rust/src/librustc/ty/context.rs:1867
             at /home/drobertson/git/rust/src/librustc/ty/context.rs:1844
             at /home/drobertson/git/rust/src/librustc/ty/context.rs:1787
             at /home/drobertson/git/rust/src/librustc/ty/context.rs:1843
  48: <std::thread::local::LocalKey<T>>::with
             at /home/drobertson/git/rust/src/librustc/ty/context.rs:1866
             at /home/drobertson/git/rust/src/librustc/ty/context.rs:1833
             at /home/drobertson/git/rust/src/libstd/thread/local.rs:294
             at /home/drobertson/git/rust/src/libstd/thread/local.rs:248
             at /home/drobertson/git/rust/src/librustc/ty/context.rs:1825
             at /home/drobertson/git/rust/src/libstd/thread/local.rs:294
             at /home/drobertson/git/rust/src/libstd/thread/local.rs:248
  49: rustc::ty::context::tls::enter_global
             at /home/drobertson/git/rust/src/librustc/ty/context.rs:1817
            at /home/drobertson/git/rust/src/librustc/ty/context.rs:1855
  50: rustc::ty::context::TyCtxt::create_and_enter
             at /home/drobertson/git/rust/src/librustc/ty/context.rs:1299
  51: rustc_driver::driver::phase_3_run_analysis_passes
             at librustc_driver/driver.rs:1095
  52: rustc_driver::driver::compile_input
             at librustc_driver/driver.rs:231
  53: rustc_driver::run_compiler_impl
             at librustc_driver/lib.rs:540
  54: <scoped_tls::ScopedKey<T>>::set
             at librustc_driver/lib.rs:457
             at /home/drobertson/.cargo/registry/src/github.com-1ecc6299db9ec823/scoped-tls-0.1.1/src/lib.rs:155
             at /home/drobertson/git/rust/src/libsyntax/lib.rs:97
             at /home/drobertson/.cargo/registry/src/github.com-1ecc6299db9ec823/scoped-tls-0.1.1/src/lib.rs:155
  55: syntax::with_globals
             at /home/drobertson/git/rust/src/libsyntax/lib.rs:96
  56: rustc_driver::run_compiler
             at librustc_driver/lib.rs:456
  57: <std::panic::AssertUnwindSafe<F> as core::ops::function::FnOnce<()>>::call_once
             at librustc_driver/lib.rs:1684
             at librustc_driver/lib.rs:174
             at librustc_driver/lib.rs:1598
             at /home/drobertson/git/rust/src/libstd/panic.rs:305
  58: __rust_maybe_catch_panic
             at libpanic_unwind/lib.rs:105
  59: std::panicking::try
             at /home/drobertson/git/rust/src/libstd/panicking.rs:289
  60: rustc_driver::run
             at librustc_driver/lib.rs:1530
             at librustc_driver/lib.rs:1597
             at librustc_driver/lib.rs:173
  61: rustc_driver::main
             at librustc_driver/lib.rs:1677
  62: std::rt::lang_start::{{closure}}
             at /home/drobertson/git/rust/src/libstd/rt.rs:74
  63: std::panicking::try::do_call
             at libstd/rt.rs:59
             at libstd/panicking.rs:310
  64: __rust_maybe_catch_panic
             at libpanic_unwind/lib.rs:105
  65: std::panicking::try
             at libstd/panicking.rs:289
  66: std::panic::catch_unwind
             at libstd/panic.rs:374
  67: std::rt::lang_start_internal
             at libstd/rt.rs:58
  68: std::rt::lang_start
             at /home/drobertson/git/rust/src/libstd/rt.rs:74
  69: __libc_start_main
  70: _start

Meta

$ rustc +stage1 --version --verbose
rustc 1.27.0-dev
binary: rustc
commit-hash: unknown
commit-date: unknown
host: x86_64-unknown-linux-gnu
release: 1.27.0-dev
LLVM version: 6.0
$ git rev-parse HEAD
0a223d139cd26e5bfab23a478a5cad845eaab131

[pietroalbini]

Was this working before or did it never work?

[dlrobertson]

Not sure honestly. Just hit the ICE randomly and then narrowed it down to a minimal example.

[pietroalbini]

OK, don't worry, thanks!

[scottmcm]

Looks like 1.26 doesn't ICE, but nightly does: https://godbolt.org/g/688aZ8

[dlrobertson]

It looks like when analyzing the closuer we run walk_struct_expr on the malformed Point structure which causes a panic here. Since typeck didn't pass we can't trust the structure of the struct to be valid for walk_struct_expr. It works if we don't walk_struct_expr or don't run the is_mentioned check if the tcx().sess has errors, but someone more experienced should probably weigh in on that. I'm not sure if that is the right approach.

[pietroalbini]

This is actually a regression from stable to beta.

[dlrobertson]

My initial theory was wrong. The problem is actually occurring in typeck here.