ICE on #![feature(rustc_insignificant_dtor)]

[PatchMixolydic]

Code

(playground)

#![feature(rustc_insignificant_dtor)]

Meta

rustc --version --verbose:

rustc 1.54.0-nightly (5dc8789e3 2021-05-21)
binary: rustc
commit-hash: 5dc8789e300930751a78996da0fa906be5a344a2
commit-date: 2021-05-21
host: x86_64-unknown-linux-gnu
release: 1.54.0-nightly
LLVM version: 12.0.1

Also reproduced on the playground: 1.54.0-nightly (2021-05-24 126561cb31e8ebe1e2dd).

Error output

thread 'rustc' panicked at 'feature `rustc_insignificant_dtor` is not declared anywhere', compiler/rustc_feature/src/lib.rs:122:21
note: run with `RUST_BACKTRACE=1` environment variable to display a backtrace

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 1.54.0-nightly (5dc8789e3 2021-05-21) running on x86_64-unknown-linux-gnu

note: compiler flags: -C embed-bitcode=no -C debuginfo=2 -C incremental --crate-type lib

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

query stack during panic:
end of query stack

Backtrace

thread 'rustc' panicked at 'feature `rustc_insignificant_dtor` is not declared anywhere', compiler/rustc_feature/src/lib.rs:122:21
stack backtrace:
   0: rust_begin_unwind
             at /rustc/5dc8789e300930751a78996da0fa906be5a344a2/library/std/src/panicking.rs:515:5
   1: std::panicking::begin_panic_fmt
             at /rustc/5dc8789e300930751a78996da0fa906be5a344a2/library/std/src/panicking.rs:457:5
   2: rustc_feature::find_feature_issue
   3: core::ops::function::FnOnce::call_once{{vtable.shim}}
   4: rustc_middle::lint::struct_lint_level::struct_lint_level_impl
   5: rustc_middle::lint::struct_lint_level
   6: rustc_lint::levels::LintLevelsBuilder::struct_lint
   7: rustc_lint::context::LintContext::struct_span_lint
   8: <core::iter::adapters::chain::Chain<A,B> as core::iter::traits::iterator::Iterator>::fold
   9: <rustc_lint::builtin::IncompleteFeatures as rustc_lint::passes::EarlyLintPass>::check_crate
  10: rustc_lint::early::check_ast_crate
  11: rustc_session::utils::<impl rustc_session::session::Session>::time
  12: rustc_interface::passes::BoxedResolver::access::{{closure}}
  13: rustc_interface::passes::configure_and_expand::{{closure}}
  14: rustc_interface::passes::BoxedResolver::access
  15: rustc_interface::queries::Queries::lower_to_hir
  16: rustc_interface::queries::Queries::global_ctxt
  17: rustc_interface::queries::<impl rustc_interface::interface::Compiler>::enter
  18: rustc_span::with_source_map
  19: scoped_tls::ScopedKey<T>::set
note: Some details are omitted, run with `RUST_BACKTRACE=full` for a verbose backtrace.

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 1.54.0-nightly (5dc8789e3 2021-05-21) running on x86_64-unknown-linux-gnu

note: compiler flags: -C embed-bitcode=no -C debuginfo=2 -C incremental --crate-type lib

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

query stack during panic:
end of query stack

Addendum

Note that similar internal feature gates don't ICE (playground):

#![feature(rustc_variance)]

error[E0635]: unknown feature `rustc_variance`
 --> src/lib.rs:1:12
  |
1 | #![feature(rustc_variance)]
  |            ^^^^^^^^^^^^^^

error: aborting due to previous error

[PatchMixolydic]

This ICE does not happen if the incomplete_features lint is allowed (playground). This may be because rustc_insignificant_dtor is listed in rustc_feature::active::INCOMPLETE_FEATURES but is not declared with declare_features!.

rust/compiler/rustc_feature/src/active.rs

Lines 679 to 699 in 1969c2e

	pub const INCOMPLETE_FEATURES: &[Symbol] = &[
	sym::if_let_guard,
	sym::impl_trait_in_bindings,
	sym::generic_associated_types,
	sym::const_generics,
	sym::let_chains,
	sym::raw_dylib,
	sym::const_evaluatable_checked,
	sym::const_trait_impl,
	sym::const_trait_bound_opt_out,
	sym::lazy_normalization_consts,
	sym::specialization,
	sym::inline_const,
	sym::repr128,
	sym::unsized_locals,
	sym::capture_disjoint_fields,
	sym::inherent_associated_types,
	sym::type_alias_impl_trait,
	sym::rustc_insignificant_dtor,
	sym::unnamed_fields,
	];

Looking at a7e1cec, it seems like I missed something: rustc_insignificant_dtor, along with rustc_variance and friends, are attributes, not feature gates. The fix might simply be to remove it from INCOMPLETE_FEATURES.