Simple array of borrowing structs panics compiler

[kennethuil]

Code

pub struct Header<'a> {
    pub value: &'a [u8],
}

pub fn test() {
    let headers = [Header{value: &[]}; 128];
}

Meta

rustc --version --verbose:

rustc 1.48.0 (7eac88abb 2020-11-16)
binary: rustc
commit-hash: 7eac88abb2e57e752f3302f02be5f3ce3d7adfb4
commit-date: 2020-11-16
host: x86_64-pc-windows-msvc
release: 1.48.0
LLVM version: 11.0

also seen in nightly:

rustc 1.50.0-nightly (0edce6f4b 2020-12-24)
binary: rustc
commit-hash: 0edce6f4bbb4514482537f569f0b8ef48e71e0a0
commit-date: 2020-12-24
host: x86_64-pc-windows-msvc
release: 1.50.0-nightly

Error output

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/issues/new?labels=C-bug%2C+I-ICE%2C+T-compiler&template=ice.md

note: rustc 1.48.0 (7eac88abb 2020-11-16) running on x86_64-pc-windows-msvc

note: compiler flags: -C debuginfo=1 -C llvm-args=--x86-asm-syntax=intel -C opt-level=3 -C embed-bitcode=no -C codegen-units=1 --crate-type rlib --crate-type lib

query stack during panic:
#0 [mir_borrowck] borrow-checking `test`
#1 [analysis] running analysis passes on this crate
end of query stack

Backtrace

thread 'rustc' panicked at 'assertion failed: promoted.is_none()', compiler\rustc_mir\src\transform\check_consts\qualifs.rs:248:9
stack backtrace:
   0:     0x7ff922a5a4a9 - <std::sys_common::backtrace::_print::DisplayBacktrace as core::fmt::Display>::fmt::hba5f685a77e920dc
   1:     0x7ff922a8748b - core::fmt::write::h7e2938de326daa9d
   2:     0x7ff922a4b998 - <std::io::IoSlice as core::fmt::Debug>::fmt::h6db1280adf9c872d
   3:     0x7ff922a5f8d4 - std::panicking::take_hook::hfb0d507d25fcd861
   4:     0x7ff922a5f4b8 - std::panicking::take_hook::hfb0d507d25fcd861
   5:     0x7ff9188faa45 - rustc_driver::report_ice::he237f3b59ed412a9
   6:     0x7ff922a60330 - std::panicking::rust_panic_with_hook::h67dee359ed61e799
   7:     0x7ff91bb286f4 - <rustc_mir::transform::MirSource as core::fmt::Debug>::fmt::hd5f962f5ee0af2ac
   8:     0x7ff91bb2858f - <rustc_mir::transform::MirSource as core::fmt::Debug>::fmt::hd5f962f5ee0af2ac
   9:     0x7ff91bb285ed - <rustc_mir::transform::MirSource as core::fmt::Debug>::fmt::hd5f962f5ee0af2ac
  10:     0x7ff91b82b49a - <rustc_mir::transform::check_consts::qualifs::CustomEq as rustc_mir::transform::check_consts::qualifs::Qualif>::in_adt_inherently::ha2a1515541536c41
  11:     0x7ff91b9ae5ce - rustc_mir::transform::promote_consts::collect_temps_and_candidates::h1bf2d5c6561d559e
  12:     0x7ff91b9af3fa - rustc_mir::transform::promote_consts::collect_temps_and_candidates::h1bf2d5c6561d559e
  13:     0x7ff91b9af3e2 - rustc_mir::transform::promote_consts::collect_temps_and_candidates::h1bf2d5c6561d559e
  14:     0x7ff91b9aeee7 - rustc_mir::transform::promote_consts::collect_temps_and_candidates::h1bf2d5c6561d559e
  15:     0x7ff91b9af075 - rustc_mir::transform::promote_consts::collect_temps_and_candidates::h1bf2d5c6561d559e
  16:     0x7ff91b9b4ed3 - rustc_mir::transform::promote_consts::promote_candidates::h98a0dd31ad25d6b2
  17:     0x7ff91b7b09bb - <rustc_mir::borrow_check::type_check::TypeVerifier as rustc_middle::mir::visit::Visitor>::visit_body::h5ea3273fde4f4bc1
  18:     0x7ff91b7b47e5 - <rustc_mir::borrow_check::type_check::TypeVerifier as rustc_middle::mir::visit::Visitor>::visit_body::h5ea3273fde4f4bc1
  19:     0x7ff91b7a7456 - <rustc_mir::interpret::validity::PathElem as core::fmt::Debug>::fmt::h128e031426748928
  20:     0x7ff91ba0fd5a - <rustc_mir::borrow_check::invalidation::InvalidationGenerator as rustc_middle::mir::visit::Visitor>::visit_terminator::hfdaff8c21da2232f
  21:     0x7ff91bb848a7 - rustc_mir::borrow_check::provide::h7202fa8cdf50afb4
  22:     0x7ff91b6b56a4 - <rustc_mir_build::thir::pattern::_match::split_grouped_constructors::Border as core::fmt::Debug>::fmt::h9321f32f80e86e78
  23:     0x7ff91bb819c0 - rustc_mir::borrow_check::provide::h7202fa8cdf50afb4
  24:     0x7ff91bb513ff - <rustc_mir::util::storage::AlwaysLiveLocals as core::fmt::Debug>::fmt::h35f8a9f8cd51d351
  25:     0x7ff918b17f3e - rustc_interface::interface::parse_cfgspecs::h47201cf071ea3adb
  26:     0x7ff918ac4ad8 - <rls_span::OneIndexed as core::fmt::Debug>::fmt::hc2e3aeb3277dd105
  27:     0x7ff918b1845d - rustc_interface::interface::parse_cfgspecs::h47201cf071ea3adb
  28:     0x7ff918ab5e20 - <rls_span::OneIndexed as core::fmt::Debug>::fmt::hc2e3aeb3277dd105
  29:     0x7ff918ac18bf - <rls_span::OneIndexed as core::fmt::Debug>::fmt::hc2e3aeb3277dd105
  30:     0x7ff918afd454 - <rls_span::OneIndexed as core::fmt::Debug>::fmt::hc2e3aeb3277dd105
  31:     0x7ff918b39b9d - rustc_interface::passes::QueryContext::print_stats::h581fbf5f23b6b495
  32:     0x7ff918972c70 - <rustc_expand::mbe::macro_parser::MatcherPosHandle as core::ops::deref::DerefMut>::deref_mut::h5acc804ee7cddfed
  33:     0x7ff918934eb7 - rustc_span::MultiSpan::primary_spans::h1017427bb4c1e209
  34:     0x7ff918945216 - <rustc_expand::mbe::macro_parser::MatcherPosHandle as core::ops::deref::DerefMut>::deref_mut::h5acc804ee7cddfed
  35:     0x7ff9188da209 - <rustc_incremental::assert_dep_graph::GraphvizDepGraph as rustc_graphviz::GraphWalk>::source::ha7402f5059c5d3e9
  36:     0x7ff918972dfb - <rustc_expand::mbe::macro_parser::MatcherPosHandle as core::ops::deref::DerefMut>::deref_mut::h5acc804ee7cddfed
  37:     0x7ff918941eaa - <rustc_expand::mbe::macro_parser::MatcherPosHandle as core::ops::deref::DerefMut>::deref_mut::h5acc804ee7cddfed
  38:     0x7ff91891a6dc - rustc_span::MultiSpan::primary_spans::h1017427bb4c1e209
  39:     0x7ff91893d0b4 - <rustc_expand::mbe::macro_parser::MatcherPosHandle as core::ops::deref::DerefMut>::deref_mut::h5acc804ee7cddfed
  40:     0x7ff918945d53 - <rustc_expand::mbe::macro_parser::MatcherPosHandle as core::ops::deref::DerefMut>::deref_mut::h5acc804ee7cddfed
  41:     0x7ff9188c8b53 - chalk_engine::TimeStamp::increment::h4493be1e979912d6
  42:     0x7ff922a70207 - std::sys::windows::thread::Thread::new::hb28370ce7bd0d890
  43:     0x7ff9af697034 - BaseThreadInitThunk
  44:     0x7ff9b159d0d1 - RtlUserThreadStart

[jyn514]

This also panics on 1.50.0-nightly (bb1fbbf 2020-12-22) and if you change 'a to 'static.

[jyn514]

Relevant code:

rust/compiler/rustc_mir/src/transform/check_consts/qualifs.rs

Lines 252 to 254 in 1d2730f

	// Check the qualifs of the value of `const` items.
	if let ty::ConstKind::Unevaluated(def, _, promoted) = constant.literal.val {
	assert!(promoted.is_none());

[kennethuil]

Adding #[derive(Copy, Clone)] to Header makes it successfully compile