ICE: interpret const eval failure of Unevaluated(UnevaluatedConst

[matthiaskrgr]

snippet:

pub struct Data([u8; usize::MAX >> 16]);
const _: &'static Data = &Data([0; usize::MAX >> 16]);

Version information

rustc 1.83.0-nightly (55043f067 2024-09-22)
binary: rustc
commit-hash: 55043f067dcf7067e7c6ebccf3639af94ff57bda
commit-date: 2024-09-22
host: x86_64-unknown-linux-gnu
release: 1.83.0-nightly
LLVM version: 19.1.0

Command:
/home/matthias/.rustup/toolchains/master/bin/rustc

Program output

error[E0601]: `main` function not found in crate `mvce`
 --> /tmp/icemaker_global_tempdir.uajd7BjF457F/rustc_testrunner_tmpdir_reporting.GJfRmJzXgPMl/mvce.rs:2:55
  |
2 | const _: &'static Data = &Data([0; usize::MAX >> 16]);
  |                                                       ^ consider adding a `main` function to `/tmp/icemaker_global_tempdir.uajd7BjF457F/rustc_testrunner_tmpdir_reporting.GJfRmJzXgPMl/mvce.rs`

error[E0080]: evaluation of constant value failed
 --> /tmp/icemaker_global_tempdir.uajd7BjF457F/rustc_testrunner_tmpdir_reporting.GJfRmJzXgPMl/mvce.rs:2:32
  |
2 | const _: &'static Data = &Data([0; usize::MAX >> 16]);
  |                                ^^^^^^^^^^^^^^^^^^^^^ tried to allocate more memory than available to compiler

error: internal compiler error: compiler/rustc_const_eval/src/interpret/eval_context.rs:586:33: interpret const eval failure of Unevaluated(UnevaluatedConst { def: DefId(0:7 ~ mvce[dab4]::_), args: [], promoted: Some(promoted[0]) }, &'{erased} Data) which is not in required_consts
 --> /tmp/icemaker_global_tempdir.uajd7BjF457F/rustc_testrunner_tmpdir_reporting.GJfRmJzXgPMl/mvce.rs:2:26
  |
2 | const _: &'static Data = &Data([0; usize::MAX >> 16]);
  |                          ^^^^^^^^^^^^^^^^^^^^^^^^^^^^

thread 'rustc' panicked at compiler/rustc_const_eval/src/interpret/eval_context.rs:586:33:
Box<dyn Any>
stack backtrace:
   0:     0x7c179568af1a - <std::sys::backtrace::BacktraceLock::print::DisplayBacktrace as core::fmt::Display>::fmt::hd890a259e842de86
   1:     0x7c1795e03666 - core::fmt::write::ha27dfc921a37964e
   2:     0x7c1796d02333 - std::io::Write::write_fmt::h70c8a0cc59cad0a8
   3:     0x7c179568ad72 - std::sys::backtrace::BacktraceLock::print::h3013cc5c3ae4074f
   4:     0x7c179568d4f1 - std::panicking::default_hook::{{closure}}::h9e5c041fcf401891
   5:     0x7c179568d324 - std::panicking::default_hook::h788b5d87547559ac
   6:     0x7c179478495f - std[232e32126cf29c33]::panicking::update_hook::<alloc[d4d13292f8c1d48d]::boxed::Box<rustc_driver_impl[b1c9e4000593b067]::install_ice_hook::{closure#0}>>::{closure#0}
   7:     0x7c179568dc08 - std::panicking::rust_panic_with_hook::hb1c7ebf17e599033
   8:     0x7c17947bf061 - std[232e32126cf29c33]::panicking::begin_panic::<rustc_errors[c0761d72276853f8]::ExplicitBug>::{closure#0}
   9:     0x7c17947b2106 - std[232e32126cf29c33]::sys::backtrace::__rust_end_short_backtrace::<std[232e32126cf29c33]::panicking::begin_panic<rustc_errors[c0761d72276853f8]::ExplicitBug>::{closure#0}, !>
  10:     0x7c17947ad5d9 - std[232e32126cf29c33]::panicking::begin_panic::<rustc_errors[c0761d72276853f8]::ExplicitBug>
  11:     0x7c17947c88b1 - <rustc_errors[c0761d72276853f8]::diagnostic::BugAbort as rustc_errors[c0761d72276853f8]::diagnostic::EmissionGuarantee>::emit_producing_guarantee
  12:     0x7c17946da6fd - <rustc_errors[c0761d72276853f8]::DiagCtxtHandle>::span_bug::<rustc_span[4e9173d9ab4d4daa]::span_encoding::Span, alloc[d4d13292f8c1d48d]::string::String>
  13:     0x7c17946f60d8 - rustc_middle[2422fc0a2a72bca0]::util::bug::opt_span_bug_fmt::<rustc_span[4e9173d9ab4d4daa]::span_encoding::Span>::{closure#0}
  14:     0x7c17946f638a - rustc_middle[2422fc0a2a72bca0]::ty::context::tls::with_opt::<rustc_middle[2422fc0a2a72bca0]::util::bug::opt_span_bug_fmt<rustc_span[4e9173d9ab4d4daa]::span_encoding::Span>::{closure#0}, !>::{closure#0}
  15:     0x7c17946ea51b - rustc_middle[2422fc0a2a72bca0]::ty::context::tls::with_context_opt::<rustc_middle[2422fc0a2a72bca0]::ty::context::tls::with_opt<rustc_middle[2422fc0a2a72bca0]::util::bug::opt_span_bug_fmt<rustc_span[4e9173d9ab4d4daa]::span_encoding::Span>::{closure#0}, !>::{closure#0}, !>
  16:     0x7c179367c547 - rustc_middle[2422fc0a2a72bca0]::util::bug::span_bug_fmt::<rustc_span[4e9173d9ab4d4daa]::span_encoding::Span>
  17:     0x7c17968eb5b4 - <rustc_const_eval[52bfe85ce8cf4586]::interpret::eval_context::InterpCx<rustc_const_eval[52bfe85ce8cf4586]::const_eval::machine::CompileTimeMachine>>::eval_rvalue_into_place
  18:     0x7c17936fadd2 - rustc_const_eval[52bfe85ce8cf4586]::const_eval::eval_queries::eval_to_allocation_raw_provider
  19:     0x7c1796501bb6 - rustc_query_impl[68ff1bc69f23602]::plumbing::__rust_begin_short_backtrace::<rustc_query_impl[68ff1bc69f23602]::query_impl::eval_to_allocation_raw::dynamic_query::{closure#2}::{closure#0}, rustc_middle[2422fc0a2a72bca0]::query::erase::Erased<[u8; 24usize]>>
  20:     0x7c1796502bef - <rustc_query_impl[68ff1bc69f23602]::query_impl::eval_to_allocation_raw::dynamic_query::{closure#2} as core[7ac7550d2f2632cb]::ops::function::FnOnce<(rustc_middle[2422fc0a2a72bca0]::ty::context::TyCtxt, rustc_middle[2422fc0a2a72bca0]::ty::ParamEnvAnd<rustc_middle[2422fc0a2a72bca0]::mir::interpret::GlobalId>)>>::call_once
  21:     0x7c1796502b71 - <rustc_query_system[67db78f99bfebbdc]::query::plumbing::execute_job_incr<rustc_query_impl[68ff1bc69f23602]::DynamicConfig<rustc_query_system[67db78f99bfebbdc]::query::caches::DefaultCache<rustc_middle[2422fc0a2a72bca0]::ty::ParamEnvAnd<rustc_middle[2422fc0a2a72bca0]::mir::interpret::GlobalId>, rustc_middle[2422fc0a2a72bca0]::query::erase::Erased<[u8; 24usize]>>, false, false, false>, rustc_query_impl[68ff1bc69f23602]::plumbing::QueryCtxt>::{closure#2}::{closure#2} as core[7ac7550d2f2632cb]::ops::function::FnOnce<((rustc_query_impl[68ff1bc69f23602]::plumbing::QueryCtxt, rustc_query_impl[68ff1bc69f23602]::DynamicConfig<rustc_query_system[67db78f99bfebbdc]::query::caches::DefaultCache<rustc_middle[2422fc0a2a72bca0]::ty::ParamEnvAnd<rustc_middle[2422fc0a2a72bca0]::mir::interpret::GlobalId>, rustc_middle[2422fc0a2a72bca0]::query::erase::Erased<[u8; 24usize]>>, false, false, false>), rustc_middle[2422fc0a2a72bca0]::ty::ParamEnvAnd<rustc_middle[2422fc0a2a72bca0]::mir::interpret::GlobalId>)>>::call_once
  22:     0x7c17965181ae - rustc_query_system[67db78f99bfebbdc]::query::plumbing::try_execute_query::<rustc_query_impl[68ff1bc69f23602]::DynamicConfig<rustc_query_system[67db78f99bfebbdc]::query::caches::DefaultCache<rustc_middle[2422fc0a2a72bca0]::ty::ParamEnvAnd<rustc_middle[2422fc0a2a72bca0]::mir::interpret::GlobalId>, rustc_middle[2422fc0a2a72bca0]::query::erase::Erased<[u8; 24usize]>>, false, false, false>, rustc_query_impl[68ff1bc69f23602]::plumbing::QueryCtxt, true>
  23:     0x7c17965176b6 - rustc_query_impl[68ff1bc69f23602]::query_impl::eval_to_allocation_raw::get_query_incr::__rust_end_short_backtrace
  24:     0x7c1796502e2e - rustc_const_eval[52bfe85ce8cf4586]::const_eval::eval_queries::eval_to_const_value_raw_provider
  25:     0x7c1796502c36 - rustc_query_impl[68ff1bc69f23602]::plumbing::__rust_begin_short_backtrace::<rustc_query_impl[68ff1bc69f23602]::query_impl::eval_to_const_value_raw::dynamic_query::{closure#2}::{closure#0}, rustc_middle[2422fc0a2a72bca0]::query::erase::Erased<[u8; 24usize]>>
  26:     0x7c1796502baf - <rustc_query_impl[68ff1bc69f23602]::query_impl::eval_to_const_value_raw::dynamic_query::{closure#2} as core[7ac7550d2f2632cb]::ops::function::FnOnce<(rustc_middle[2422fc0a2a72bca0]::ty::context::TyCtxt, rustc_middle[2422fc0a2a72bca0]::ty::ParamEnvAnd<rustc_middle[2422fc0a2a72bca0]::mir::interpret::GlobalId>)>>::call_once
  27:     0x7c1796502b71 - <rustc_query_system[67db78f99bfebbdc]::query::plumbing::execute_job_incr<rustc_query_impl[68ff1bc69f23602]::DynamicConfig<rustc_query_system[67db78f99bfebbdc]::query::caches::DefaultCache<rustc_middle[2422fc0a2a72bca0]::ty::ParamEnvAnd<rustc_middle[2422fc0a2a72bca0]::mir::interpret::GlobalId>, rustc_middle[2422fc0a2a72bca0]::query::erase::Erased<[u8; 24usize]>>, false, false, false>, rustc_query_impl[68ff1bc69f23602]::plumbing::QueryCtxt>::{closure#2}::{closure#2} as core[7ac7550d2f2632cb]::ops::function::FnOnce<((rustc_query_impl[68ff1bc69f23602]::plumbing::QueryCtxt, rustc_query_impl[68ff1bc69f23602]::DynamicConfig<rustc_query_system[67db78f99bfebbdc]::query::caches::DefaultCache<rustc_middle[2422fc0a2a72bca0]::ty::ParamEnvAnd<rustc_middle[2422fc0a2a72bca0]::mir::interpret::GlobalId>, rustc_middle[2422fc0a2a72bca0]::query::erase::Erased<[u8; 24usize]>>, false, false, false>), rustc_middle[2422fc0a2a72bca0]::ty::ParamEnvAnd<rustc_middle[2422fc0a2a72bca0]::mir::interpret::GlobalId>)>>::call_once
  28:     0x7c17965181ae - rustc_query_system[67db78f99bfebbdc]::query::plumbing::try_execute_query::<rustc_query_impl[68ff1bc69f23602]::DynamicConfig<rustc_query_system[67db78f99bfebbdc]::query::caches::DefaultCache<rustc_middle[2422fc0a2a72bca0]::ty::ParamEnvAnd<rustc_middle[2422fc0a2a72bca0]::mir::interpret::GlobalId>, rustc_middle[2422fc0a2a72bca0]::query::erase::Erased<[u8; 24usize]>>, false, false, false>, rustc_query_impl[68ff1bc69f23602]::plumbing::QueryCtxt, true>
  29:     0x7c1796517a4c - rustc_query_impl[68ff1bc69f23602]::query_impl::eval_to_const_value_raw::get_query_incr::__rust_end_short_backtrace
  30:     0x7c1796197c3d - <rustc_middle[2422fc0a2a72bca0]::hir::map::Map>::par_body_owners::<rustc_hir_analysis[2606297559afc5bb]::check_crate::{closure#3}>::{closure#0}
  31:     0x7c17961954d2 - rustc_hir_analysis[2606297559afc5bb]::check_crate
  32:     0x7c1796191e05 - rustc_interface[3feab42be5996c7]::passes::run_required_analyses
  33:     0x7c1796a2a29e - rustc_interface[3feab42be5996c7]::passes::analysis
  34:     0x7c1796a2a271 - rustc_query_impl[68ff1bc69f23602]::plumbing::__rust_begin_short_backtrace::<rustc_query_impl[68ff1bc69f23602]::query_impl::analysis::dynamic_query::{closure#2}::{closure#0}, rustc_middle[2422fc0a2a72bca0]::query::erase::Erased<[u8; 1usize]>>
  35:     0x7c1796f261c1 - rustc_query_system[67db78f99bfebbdc]::query::plumbing::try_execute_query::<rustc_query_impl[68ff1bc69f23602]::DynamicConfig<rustc_query_system[67db78f99bfebbdc]::query::caches::SingleCache<rustc_middle[2422fc0a2a72bca0]::query::erase::Erased<[u8; 1usize]>>, false, false, false>, rustc_query_impl[68ff1bc69f23602]::plumbing::QueryCtxt, true>
  36:     0x7c1796f25e7a - rustc_query_impl[68ff1bc69f23602]::query_impl::analysis::get_query_incr::__rust_end_short_backtrace
  37:     0x7c1796b399de - rustc_interface[3feab42be5996c7]::interface::run_compiler::<core[7ac7550d2f2632cb]::result::Result<(), rustc_span[4e9173d9ab4d4daa]::ErrorGuaranteed>, rustc_driver_impl[b1c9e4000593b067]::run_compiler::{closure#0}>::{closure#1}
  38:     0x7c1796bc4990 - std[232e32126cf29c33]::sys::backtrace::__rust_begin_short_backtrace::<rustc_interface[3feab42be5996c7]::util::run_in_thread_with_globals<rustc_interface[3feab42be5996c7]::util::run_in_thread_pool_with_globals<rustc_interface[3feab42be5996c7]::interface::run_compiler<core[7ac7550d2f2632cb]::result::Result<(), rustc_span[4e9173d9ab4d4daa]::ErrorGuaranteed>, rustc_driver_impl[b1c9e4000593b067]::run_compiler::{closure#0}>::{closure#1}, core[7ac7550d2f2632cb]::result::Result<(), rustc_span[4e9173d9ab4d4daa]::ErrorGuaranteed>>::{closure#0}, core[7ac7550d2f2632cb]::result::Result<(), rustc_span[4e9173d9ab4d4daa]::ErrorGuaranteed>>::{closure#0}::{closure#0}, core[7ac7550d2f2632cb]::result::Result<(), rustc_span[4e9173d9ab4d4daa]::ErrorGuaranteed>>
  39:     0x7c1796bc4ffa - <<std[232e32126cf29c33]::thread::Builder>::spawn_unchecked_<rustc_interface[3feab42be5996c7]::util::run_in_thread_with_globals<rustc_interface[3feab42be5996c7]::util::run_in_thread_pool_with_globals<rustc_interface[3feab42be5996c7]::interface::run_compiler<core[7ac7550d2f2632cb]::result::Result<(), rustc_span[4e9173d9ab4d4daa]::ErrorGuaranteed>, rustc_driver_impl[b1c9e4000593b067]::run_compiler::{closure#0}>::{closure#1}, core[7ac7550d2f2632cb]::result::Result<(), rustc_span[4e9173d9ab4d4daa]::ErrorGuaranteed>>::{closure#0}, core[7ac7550d2f2632cb]::result::Result<(), rustc_span[4e9173d9ab4d4daa]::ErrorGuaranteed>>::{closure#0}::{closure#0}, core[7ac7550d2f2632cb]::result::Result<(), rustc_span[4e9173d9ab4d4daa]::ErrorGuaranteed>>::{closure#1} as core[7ac7550d2f2632cb]::ops::function::FnOnce<()>>::call_once::{shim:vtable#0}
  40:     0x7c1796bc53eb - std::sys::pal::unix::thread::Thread::new::thread_start::h6e4c0266f3b27cf2
  41:     0x7c179825939d - <unknown>
  42:     0x7c17982de49c - <unknown>
  43:                0x0 - <unknown>

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: please make sure that you have updated to the latest nightly

note: rustc 1.83.0-nightly (55043f067 2024-09-22) running on x86_64-unknown-linux-gnu

note: compiler flags: -Z incremental-verify-ich=yes -C incremental=[REDACTED] -C debuginfo=2 -C link-dead-code=true -Z validate-mir

query stack during panic:
#0 [eval_to_allocation_raw] const-evaluating + checking `_`
#1 [eval_to_const_value_raw] simplifying constant for the type system `_`
end of query stack
error: aborting due to 3 previous errors

Some errors have detailed explanations: E0080, E0601.
For more information about an error, try `rustc --explain E0080`.

[matthiaskrgr]

Regression in #127546 cc @workingjubilee

[saethlin]

Nope. That PR just changed the size at which things become problematic, which should tell you that the bisection is wrong. If you tweak the constants just a little bit:

pub struct Data([u8; usize::MAX >> 17]);
const _: &'static Data = &Data([0; usize::MAX >> 17]);

This bisects instead to #121557

[workingjubilee]

is "the compiler OOMs when you try to make it OOM" really a "regression"?

[workingjubilee]

answer after some discussion: possibly, if it was supposed to stop compilation when it detected it was going to OOM if it continued!

[RalfJung]

Ah, exciting... there is indeed a way that all constants can fail to evaluate, even those that have been promoted because they seem "infallible".