ICE: `expected ConstKind::Value, got Unevaluated(UnevaluatedConst...`

[matthiaskrgr]

Code

#![feature(generic_const_exprs)]

mod assert {
    use std::mem::{Assume, BikeshedIntrinsicFrom};

    pub fn is_transmutable<
        Src,
        Dst,
        Context,
        const ASSUME_ALIGNMENT: bool,
        const ASSUME_LIFETIMES: bool,
        const ASSUME_SAFETY: bool,
        const ASSUME_VALIDITY: bool,
    >()
    where
        Dst: BikeshedIntrinsicFrom<
            Src,
            Context,
            { from_options(ASSUME_ALIGNMENT, ASSUME_LIFETIMES, ASSUME_SAFETY, ASSUME_VALIDITY) }
        >,
    {}

    const fn from_options(
        ,
        ,
        ,
        ,
    ) -> Assume {}
}

fn test() {
    struct Context;
    #[repr(C)] struct Src;
    #[repr(C)] struct Dst;
     
    false(); 
    assert::is_transmutable::<Src, Dst, Context, false, false, { true }, false>(); 
     
}

Meta

rustc --version --verbose:

rustc 1.71.0-nightly (1c42cb4ef 2023-04-26)
binary: rustc
commit-hash: 1c42cb4ef0544fbfaa500216e53382d6b079c001
commit-date: 2023-04-26
host: x86_64-unknown-linux-gnu
release: 1.71.0-nightly
LLVM version: 16.0.2

Error output

yes

Backtrace

error: internal compiler error: compiler/rustc_middle/src/ty/consts.rs:159:18: expected ConstKind::Value, got Unevaluated(UnevaluatedConst { def: DefId(0:15 ~ treereduce[c646]::assert::is_transmutable::{constant#0}), substs: [test::Src, test::Dst, test::Context, Const { ty: bool, kind: Value(Leaf(0x00)) }, Const { ty: bool, kind: Value(Leaf(0x00)) }, Const { ty: bool, kind: Value(Leaf(0x01)) }, Const { ty: bool, kind: Value(Leaf(0x00)) }] })

thread 'rustc' panicked at 'Box<dyn Any>', /rustc/1c42cb4ef0544fbfaa500216e53382d6b079c001/compiler/rustc_errors/src/lib.rs:1643:9
stack backtrace:
   0:     0x7f78d4f68e73 - std::backtrace_rs::backtrace::libunwind::trace::h0c8179e89cc9893e
                               at /rustc/1c42cb4ef0544fbfaa500216e53382d6b079c001/library/std/src/../../backtrace/src/backtrace/libunwind.rs:93:5
   1:     0x7f78d4f68e73 - std::backtrace_rs::backtrace::trace_unsynchronized::hfadffaff9fceb6ba
                               at /rustc/1c42cb4ef0544fbfaa500216e53382d6b079c001/library/std/src/../../backtrace/src/backtrace/mod.rs:66:5
   2:     0x7f78d4f68e73 - std::sys_common::backtrace::_print_fmt::ha49f609af156c4cb
                               at /rustc/1c42cb4ef0544fbfaa500216e53382d6b079c001/library/std/src/sys_common/backtrace.rs:65:5
   3:     0x7f78d4f68e73 - <std::sys_common::backtrace::_print::DisplayBacktrace as core::fmt::Display>::fmt::h0ad104dc9ebb0bab
                               at /rustc/1c42cb4ef0544fbfaa500216e53382d6b079c001/library/std/src/sys_common/backtrace.rs:44:22
   4:     0x7f78d4fc9c8f - core::fmt::write::h076b507083203424
                               at /rustc/1c42cb4ef0544fbfaa500216e53382d6b079c001/library/core/src/fmt/mod.rs:1247:17
   5:     0x7f78d4f5bea1 - std::io::Write::write_fmt::ha4c326e8c8c981e1
                               at /rustc/1c42cb4ef0544fbfaa500216e53382d6b079c001/library/std/src/io/mod.rs:1712:15
   6:     0x7f78d4f68c85 - std::sys_common::backtrace::_print::hbc9e8503f2c8583b
                               at /rustc/1c42cb4ef0544fbfaa500216e53382d6b079c001/library/std/src/sys_common/backtrace.rs:47:5
   7:     0x7f78d4f68c85 - std::sys_common::backtrace::print::he24fec1d9c5516a7
                               at /rustc/1c42cb4ef0544fbfaa500216e53382d6b079c001/library/std/src/sys_common/backtrace.rs:34:9
   8:     0x7f78d4f6b847 - std::panicking::default_hook::{{closure}}::hf29caaf6379226a6
   9:     0x7f78d4f6b635 - std::panicking::default_hook::h0765c9476c979227
                               at /rustc/1c42cb4ef0544fbfaa500216e53382d6b079c001/library/std/src/panicking.rs:288:9
  10:     0x7f78d81bf8c5 - <rustc_driver_impl[b4ece89b41fa04d8]::DEFAULT_HOOK::{closure#0}::{closure#0} as core[a53159a38bb5d97c]::ops::function::FnOnce<(&core[a53159a38bb5d97c]::panic::panic_info::PanicInfo,)>>::call_once::{shim:vtable#0}
  11:     0x7f78d4f6bf85 - <alloc::boxed::Box<F,A> as core::ops::function::Fn<Args>>::call::h7a83df3f1b1b39ec
                               at /rustc/1c42cb4ef0544fbfaa500216e53382d6b079c001/library/alloc/src/boxed.rs:1976:9
  12:     0x7f78d4f6bf85 - std::panicking::rust_panic_with_hook::h060701a46b500fdf
                               at /rustc/1c42cb4ef0544fbfaa500216e53382d6b079c001/library/std/src/panicking.rs:695:13
  13:     0x7f78d86cf0d1 - std[b0e36382822581c2]::panicking::begin_panic::<rustc_errors[e242ea0d30f7fc85]::ExplicitBug>::{closure#0}
  14:     0x7f78d86cdeb6 - std[b0e36382822581c2]::sys_common::backtrace::__rust_end_short_backtrace::<std[b0e36382822581c2]::panicking::begin_panic<rustc_errors[e242ea0d30f7fc85]::ExplicitBug>::{closure#0}, !>
  15:     0x7f78d8695da6 - std[b0e36382822581c2]::panicking::begin_panic::<rustc_errors[e242ea0d30f7fc85]::ExplicitBug>
  16:     0x7f78d87174d6 - <rustc_errors[e242ea0d30f7fc85]::HandlerInner>::bug::<&alloc[5698eed4a099ff47]::string::String>
  17:     0x7f78d87171a0 - <rustc_errors[e242ea0d30f7fc85]::Handler>::bug::<&alloc[5698eed4a099ff47]::string::String>
  18:     0x7f78d87107bb - rustc_middle[74d31bc1c7288efd]::util::bug::opt_span_bug_fmt::<rustc_span[5acbb0d3e38bbf81]::span_encoding::Span>::{closure#0}
  19:     0x7f78d870e0fa - rustc_middle[74d31bc1c7288efd]::ty::context::tls::with_opt::<rustc_middle[74d31bc1c7288efd]::util::bug::opt_span_bug_fmt<rustc_span[5acbb0d3e38bbf81]::span_encoding::Span>::{closure#0}, !>::{closure#0}
  20:     0x7f78d870e0ca - rustc_middle[74d31bc1c7288efd]::ty::context::tls::with_context_opt::<rustc_middle[74d31bc1c7288efd]::ty::context::tls::with_opt<rustc_middle[74d31bc1c7288efd]::util::bug::opt_span_bug_fmt<rustc_span[5acbb0d3e38bbf81]::span_encoding::Span>::{closure#0}, !>::{closure#0}, !>
  21:     0x7f78d638cd0d - rustc_middle[74d31bc1c7288efd]::util::bug::bug_fmt
  22:     0x7f78d8691ed6 - <rustc_middle[74d31bc1c7288efd]::ty::consts::Const>::to_valtree
  23:     0x7f78d8ee52de - <rustc_transmute[1ee791244e44a281]::Assume>::from_const
  24:     0x7f78d6aae5b9 - <rustc_trait_selection[ce8ecfa74af62748]::traits::select::SelectionContext>::confirm_candidate
  25:     0x7f78d6aa0d6f - <rustc_trait_selection[ce8ecfa74af62748]::traits::select::SelectionContext>::evaluate_stack
  26:     0x7f78d6a9f3f4 - <rustc_query_system[38efe1ae13b76606]::dep_graph::graph::DepGraph<rustc_middle[74d31bc1c7288efd]::dep_graph::dep_node::DepKind>>::with_anon_task::<rustc_middle[74d31bc1c7288efd]::ty::context::TyCtxt, <rustc_trait_selection[ce8ecfa74af62748]::traits::select::SelectionContext>::in_task<<rustc_trait_selection[ce8ecfa74af62748]::traits::select::SelectionContext>::evaluate_trait_predicate_recursively::{closure#0}::{closure#2}, core[a53159a38bb5d97c]::result::Result<rustc_middle[74d31bc1c7288efd]::traits::select::EvaluationResult, rustc_middle[74d31bc1c7288efd]::traits::select::OverflowError>>::{closure#0}, core[a53159a38bb5d97c]::result::Result<rustc_middle[74d31bc1c7288efd]::traits::select::EvaluationResult, rustc_middle[74d31bc1c7288efd]::traits::select::OverflowError>>
  27:     0x7f78d6ce2d2c - <rustc_trait_selection[ce8ecfa74af62748]::traits::select::SelectionContext>::evaluate_predicate_recursively
  28:     0x7f78d687ae43 - rustc_traits[bbceeee60bcdb08d]::evaluate_obligation::evaluate_obligation
  29:     0x7f78d6878b6d - rustc_query_system[38efe1ae13b76606]::query::plumbing::try_execute_query::<rustc_query_impl[d894186be28c7657]::queries::evaluate_obligation, rustc_query_impl[d894186be28c7657]::plumbing::QueryCtxt>
  30:     0x7f78d6359102 - <rustc_trait_selection[ce8ecfa74af62748]::traits::fulfill::FulfillProcessor as rustc_data_structures[ecde4e0aacf74356]::obligation_forest::ObligationProcessor>::process_obligation
  31:     0x7f78d6355399 - <rustc_data_structures[ecde4e0aacf74356]::obligation_forest::ObligationForest<rustc_trait_selection[ce8ecfa74af62748]::traits::fulfill::PendingPredicateObligation>>::process_obligations::<rustc_trait_selection[ce8ecfa74af62748]::traits::fulfill::FulfillProcessor>
  32:     0x7f78d633e7e2 - <rustc_hir_typeck[6d85701173a32a15]::fn_ctxt::FnCtxt>::check_argument_types
  33:     0x7f78d6331a9a - <rustc_hir_typeck[6d85701173a32a15]::fn_ctxt::FnCtxt>::check_call
  34:     0x7f78d6711fa6 - <rustc_hir_typeck[6d85701173a32a15]::fn_ctxt::FnCtxt>::check_expr_with_expectation_and_args
  35:     0x7f78d6759f4b - <rustc_hir_typeck[6d85701173a32a15]::fn_ctxt::FnCtxt>::check_block_with_expected
  36:     0x7f78d67127d6 - <rustc_hir_typeck[6d85701173a32a15]::fn_ctxt::FnCtxt>::check_expr_with_expectation_and_args
  37:     0x7f78d68d19ad - <rustc_hir_typeck[6d85701173a32a15]::fn_ctxt::FnCtxt>::check_return_expr
  38:     0x7f78d68c9d53 - rustc_hir_typeck[6d85701173a32a15]::check::check_fn
  39:     0x7f78d68b223e - rustc_hir_typeck[6d85701173a32a15]::typeck
  40:     0x7f78d68a70b6 - rustc_query_system[38efe1ae13b76606]::query::plumbing::try_execute_query::<rustc_query_impl[d894186be28c7657]::queries::typeck, rustc_query_impl[d894186be28c7657]::plumbing::QueryCtxt>
  41:     0x7f78d71fc5d0 - rustc_query_system[38efe1ae13b76606]::query::plumbing::try_execute_query::<rustc_query_impl[d894186be28c7657]::queries::used_trait_imports, rustc_query_impl[d894186be28c7657]::plumbing::QueryCtxt>
  42:     0x7f78d7698145 - rustc_hir_analysis[72726d43727a00d0]::check_crate
  43:     0x7f78d769201d - rustc_interface[69aa8c17999313ff]::passes::analysis
  44:     0x7f78d793e3a2 - rustc_query_system[38efe1ae13b76606]::query::plumbing::try_execute_query::<rustc_query_impl[d894186be28c7657]::queries::analysis, rustc_query_impl[d894186be28c7657]::plumbing::QueryCtxt>
  45:     0x7f78d793e0b0 - <rustc_query_impl[d894186be28c7657]::Queries as rustc_middle[74d31bc1c7288efd]::ty::query::QueryEngine>::analysis
  46:     0x7f78d73ba90a - <rustc_middle[74d31bc1c7288efd]::ty::context::GlobalCtxt>::enter::<rustc_driver_impl[b4ece89b41fa04d8]::run_compiler::{closure#1}::{closure#2}::{closure#4}, core[a53159a38bb5d97c]::result::Result<(), rustc_span[5acbb0d3e38bbf81]::ErrorGuaranteed>>
  47:     0x7f78d73b9b48 - <rustc_interface[69aa8c17999313ff]::interface::Compiler>::enter::<rustc_driver_impl[b4ece89b41fa04d8]::run_compiler::{closure#1}::{closure#2}, core[a53159a38bb5d97c]::result::Result<core[a53159a38bb5d97c]::option::Option<rustc_interface[69aa8c17999313ff]::queries::Linker>, rustc_span[5acbb0d3e38bbf81]::ErrorGuaranteed>>
  48:     0x7f78d73b7b6f - rustc_span[5acbb0d3e38bbf81]::set_source_map::<core[a53159a38bb5d97c]::result::Result<(), rustc_span[5acbb0d3e38bbf81]::ErrorGuaranteed>, rustc_interface[69aa8c17999313ff]::interface::run_compiler<core[a53159a38bb5d97c]::result::Result<(), rustc_span[5acbb0d3e38bbf81]::ErrorGuaranteed>, rustc_driver_impl[b4ece89b41fa04d8]::run_compiler::{closure#1}>::{closure#0}::{closure#0}>
  49:     0x7f78d73b7200 - std[b0e36382822581c2]::sys_common::backtrace::__rust_begin_short_backtrace::<rustc_interface[69aa8c17999313ff]::util::run_in_thread_pool_with_globals<rustc_interface[69aa8c17999313ff]::interface::run_compiler<core[a53159a38bb5d97c]::result::Result<(), rustc_span[5acbb0d3e38bbf81]::ErrorGuaranteed>, rustc_driver_impl[b4ece89b41fa04d8]::run_compiler::{closure#1}>::{closure#0}, core[a53159a38bb5d97c]::result::Result<(), rustc_span[5acbb0d3e38bbf81]::ErrorGuaranteed>>::{closure#0}::{closure#0}, core[a53159a38bb5d97c]::result::Result<(), rustc_span[5acbb0d3e38bbf81]::ErrorGuaranteed>>
  50:     0x7f78d73b6b21 - <<std[b0e36382822581c2]::thread::Builder>::spawn_unchecked_<rustc_interface[69aa8c17999313ff]::util::run_in_thread_pool_with_globals<rustc_interface[69aa8c17999313ff]::interface::run_compiler<core[a53159a38bb5d97c]::result::Result<(), rustc_span[5acbb0d3e38bbf81]::ErrorGuaranteed>, rustc_driver_impl[b4ece89b41fa04d8]::run_compiler::{closure#1}>::{closure#0}, core[a53159a38bb5d97c]::result::Result<(), rustc_span[5acbb0d3e38bbf81]::ErrorGuaranteed>>::{closure#0}::{closure#0}, core[a53159a38bb5d97c]::result::Result<(), rustc_span[5acbb0d3e38bbf81]::ErrorGuaranteed>>::{closure#1} as core[a53159a38bb5d97c]::ops::function::FnOnce<()>>::call_once::{shim:vtable#0}
  51:     0x7f78d4f76365 - <alloc::boxed::Box<F,A> as core::ops::function::FnOnce<Args>>::call_once::h2b4cb02d9a218e1d
                               at /rustc/1c42cb4ef0544fbfaa500216e53382d6b079c001/library/alloc/src/boxed.rs:1962:9
  52:     0x7f78d4f76365 - <alloc::boxed::Box<F,A> as core::ops::function::FnOnce<Args>>::call_once::hbd8144eacfab6e10
                               at /rustc/1c42cb4ef0544fbfaa500216e53382d6b079c001/library/alloc/src/boxed.rs:1962:9
  53:     0x7f78d4f76365 - std::sys::unix::thread::Thread::new::thread_start::h95499a4b2fca6f4a
                               at /rustc/1c42cb4ef0544fbfaa500216e53382d6b079c001/library/std/src/sys/unix/thread.rs:108:17
  54:     0x7f78d4d10bb5 - <unknown>
  55:     0x7f78d4d92d90 - <unknown>
  56:                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: rustc 1.71.0-nightly (1c42cb4ef 2023-04-26) running on x86_64-unknown-linux-gnu

query stack during panic:
#0 [evaluate_obligation] evaluating trait selection obligation `test::Dst: core::mem::transmutability::BikeshedIntrinsicFrom<test::Src, test::Context, { from_options(ASSUME_ALIGNMENT, ASSUME_LIFETIMES, ASSUME_SAFETY, ASSUME_VALIDITY) }>`
#1 [typeck] type-checking `test`
#2 [used_trait_imports] finding used_trait_imports `test`
#3 [analysis] running analysis passes on this crate
end of query stack
error: aborting due to 12 previous errors; 2 warnings emitted

Some errors have detailed explanations: E0308, E0601, E0618, E0658.
For more information about an error, try `rustc --explain E0308`.

[bryangarza]

It's coming from calling ty::consts::Const::to_valtree() at this line:

rust/compiler/rustc_transmute/src/lib.rs

Line 141 in 1a6ae3d

let fields = c.to_valtree().unwrap_branch();

I can take a look at it later, doesn't seem to be related to recent changes. Nice find. We're mistakenly assuming that the const has always already been evaluated by the time confirm_transmutability_candidate(...) is called.

@rustbot claim

[matthiaskrgr]

This one also seems to be regressing in 6cd6bad 🤔
#101692 cc @cjgillot