ICE: `layout.is_sized()`

[matthiaskrgr]

auto-reduced (treereduce-rust):

//@compile-flags: -Zmir-opt-level=5 -Zvalidate-mir



enum E { V16(u16), V32(u32) }
static C: (E, u16, str) = (, 0x600D, 0xBAD);

pub fn main() {
    let (_, n, _) = C;
    
    
}

original:

//@ run-pass
#![allow(dead_code)]

enum E { V16(u16), V32(u32) }
static C: (E, u16, str) = (E::V16(0xDEAD), 0x600D, 0xBAD);

pub fn main() {
    let (_, n, _) = C;
    assert!(n != 0xBAD);
    assert_eq!(n, 0x600D);
}

Version information

rustc 1.88.0-nightly (40dacd50b 2025-04-15)
binary: rustc
commit-hash: 40dacd50b7074783db748d73925ac5c3693a7ec1
commit-date: 2025-04-15
host: x86_64-unknown-linux-gnu
release: 1.88.0-nightly
LLVM version: 20.1.2

Possibly related line of code:

rust/compiler/rustc_middle/src/mir/interpret/mod.rs

Lines 366 to 378 in 40dacd5

	// * be able to get information on extern statics.
	let ty = tcx
	.type_of(def_id)
	.no_bound_vars()
	.expect("statics should not have generic parameters");
	let layout = tcx.layout_of(typing_env.as_query_input(ty)).unwrap();
	assert!(layout.is_sized());
	(layout.size, layout.align.abi)
	}
	}
	GlobalAlloc::Memory(alloc) => {
	let alloc = alloc.inner();
	(alloc.size(), alloc.align)

Command:
/home/matthias/.rustup/toolchains/master/bin/rustc -Zmir-opt-level=5 -Zvalidate-mir

Program output

error: expected expression, found `,`
 --> /tmp/icemaker_global_tempdir.3AprGNyTl55i/rustc_testrunner_tmpdir_reporting.bRtgIyNkaXla/mvce.rs:5:28
  |
5 | static C: (E, u16, str) = (, 0x600D, 0xBAD);
  |                            ^ expected expression

error[E0277]: the size for values of type `str` cannot be known at compilation time
 --> /tmp/icemaker_global_tempdir.3AprGNyTl55i/rustc_testrunner_tmpdir_reporting.bRtgIyNkaXla/mvce.rs:5:11
  |
5 | static C: (E, u16, str) = (, 0x600D, 0xBAD);
  |           ^^^^^^^^^^^^^ doesn't have a size known at compile-time
  |
  = help: within `(E, u16, str)`, the trait `Sized` is not implemented for `str`
  = note: required because it appears within the type `(E, u16, str)`
  = note: statics and constants must have a statically known size

warning: unused variable: `n`
 --> /tmp/icemaker_global_tempdir.3AprGNyTl55i/rustc_testrunner_tmpdir_reporting.bRtgIyNkaXla/mvce.rs:8:13
  |
8 |     let (_, n, _) = C;
  |             ^ help: if this is intentional, prefix it with an underscore: `_n`
  |
  = note: `#[warn(unused_variables)]` on by default


thread 'rustc' panicked at compiler/rustc_middle/src/mir/interpret/mod.rs:372:21:
assertion failed: layout.is_sized()
stack backtrace:
   0:     0x7f16c90e36f3 - <std::sys::backtrace::BacktraceLock::print::DisplayBacktrace as core::fmt::Display>::fmt::hac1fd18538367f85
   1:     0x7f16c9806087 - core::fmt::write::h355b50e2dd48b7cb
   2:     0x7f16cacaab91 - std::io::Write::write_fmt::h3c208cfcae87fbc5
   3:     0x7f16c90e3552 - std::sys::backtrace::BacktraceLock::print::h52bf60fe66a866b6
   4:     0x7f16c90e703a - std::panicking::default_hook::{{closure}}::ha54cd4f331000bf4
   5:     0x7f16c90e6bbf - std::panicking::default_hook::h65502b75eb6b3c4d
   6:     0x7f16c815b843 - std[6f1f62f9e1890267]::panicking::update_hook::<alloc[9c10c445f94edf6f]::boxed::Box<rustc_driver_impl[261694032873b461]::install_ice_hook::{closure#1}>>::{closure#0}
   7:     0x7f16c90e78b3 - std::panicking::rust_panic_with_hook::h9f8305ffe577d3e1
   8:     0x7f16c90e7576 - std::panicking::begin_panic_handler::{{closure}}::h1196da9ca3c9caa6
   9:     0x7f16c90e3bb9 - std::sys::backtrace::__rust_end_short_backtrace::h209d7d99dc310f1c
  10:     0x7f16c90e726d - __rustc[de9843575c99dce8]::rust_begin_unwind
  11:     0x7f16c5a8a680 - core::panicking::panic_fmt::h42dd318a0e6082fa
  12:     0x7f16c5a8f62c - core::panicking::panic::hb0960e31c93bed80
  13:     0x7f16cae0181e - <rustc_middle[2dc3a1ceabbabe6a]::mir::interpret::GlobalAlloc>::size_and_align.cold
  14:     0x7f16ca324c6a - <rustc_const_eval[ae92fa6a8d266fb6]::interpret::eval_context::InterpCx<rustc_const_eval[ae92fa6a8d266fb6]::const_eval::dummy_machine::DummyMachine>>::get_alloc_info
  15:     0x7f16ca334d58 - <rustc_const_eval[ae92fa6a8d266fb6]::interpret::eval_context::InterpCx<rustc_const_eval[ae92fa6a8d266fb6]::const_eval::dummy_machine::DummyMachine>>::ptr_offset_inbounds
  16:     0x7f16ca334ab9 - <rustc_const_eval[ae92fa6a8d266fb6]::interpret::operand::OpTy as rustc_const_eval[ae92fa6a8d266fb6]::interpret::projection::Projectable<rustc_middle[2dc3a1ceabbabe6a]::mir::interpret::pointer::CtfeProvenance>>::offset_with_meta::<rustc_const_eval[ae92fa6a8d266fb6]::const_eval::dummy_machine::DummyMachine>
  17:     0x7f16ca334998 - <rustc_const_eval[ae92fa6a8d266fb6]::interpret::eval_context::InterpCx<rustc_const_eval[ae92fa6a8d266fb6]::const_eval::dummy_machine::DummyMachine>>::project_field::<rustc_const_eval[ae92fa6a8d266fb6]::interpret::operand::OpTy>
  18:     0x7f16ca334447 - <rustc_const_eval[ae92fa6a8d266fb6]::interpret::eval_context::InterpCx<rustc_const_eval[ae92fa6a8d266fb6]::const_eval::dummy_machine::DummyMachine>>::project::<rustc_const_eval[ae92fa6a8d266fb6]::interpret::operand::OpTy>
  19:     0x7f16ca32d176 - <rustc_mir_transform[27e09089e56c5a07]::gvn::VnState>::insert
  20:     0x7f16ca32863b - <rustc_mir_transform[27e09089e56c5a07]::gvn::VnState>::simplify_place_value
  21:     0x7f16ca327deb - <rustc_mir_transform[27e09089e56c5a07]::gvn::VnState>::simplify_operand
  22:     0x7f16c70e2b1e - <rustc_mir_transform[27e09089e56c5a07]::gvn::VnState as rustc_middle[2dc3a1ceabbabe6a]::mir::visit::MutVisitor>::visit_statement
  23:     0x7f16c70e0e97 - <rustc_mir_transform[27e09089e56c5a07]::gvn::GVN as rustc_mir_transform[27e09089e56c5a07]::pass_manager::MirPass>::run_pass
  24:     0x7f16c9803fbb - rustc_mir_transform[27e09089e56c5a07]::pass_manager::run_passes_inner
  25:     0x7f16ca376a9f - rustc_mir_transform[27e09089e56c5a07]::optimized_mir
  26:     0x7f16ca37608d - rustc_query_impl[ad69a23e50a8fbd1]::plumbing::__rust_begin_short_backtrace::<rustc_query_impl[ad69a23e50a8fbd1]::query_impl::optimized_mir::dynamic_query::{closure#2}::{closure#0}, rustc_middle[2dc3a1ceabbabe6a]::query::erase::Erased<[u8; 8usize]>>
  27:     0x7f16c9af412f - rustc_query_system[8ca381065095edd4]::query::plumbing::try_execute_query::<rustc_query_impl[ad69a23e50a8fbd1]::DynamicConfig<rustc_query_system[8ca381065095edd4]::query::caches::DefIdCache<rustc_middle[2dc3a1ceabbabe6a]::query::erase::Erased<[u8; 8usize]>>, false, false, false>, rustc_query_impl[ad69a23e50a8fbd1]::plumbing::QueryCtxt, false>
  28:     0x7f16c9af355d - rustc_query_impl[ad69a23e50a8fbd1]::query_impl::optimized_mir::get_query_non_incr::__rust_end_short_backtrace
  29:     0x7f16c9db3d46 - <rustc_middle[2dc3a1ceabbabe6a]::ty::context::TyCtxt>::instance_mir
  30:     0x7f16c9c0e0b4 - rustc_interface[f2198cb0de4afffb]::passes::run_required_analyses
  31:     0x7f16ca355f9e - rustc_interface[f2198cb0de4afffb]::passes::analysis
  32:     0x7f16ca355f73 - rustc_query_impl[ad69a23e50a8fbd1]::plumbing::__rust_begin_short_backtrace::<rustc_query_impl[ad69a23e50a8fbd1]::query_impl::analysis::dynamic_query::{closure#2}::{closure#0}, rustc_middle[2dc3a1ceabbabe6a]::query::erase::Erased<[u8; 0usize]>>
  33:     0x7f16ca7fb73d - rustc_query_system[8ca381065095edd4]::query::plumbing::try_execute_query::<rustc_query_impl[ad69a23e50a8fbd1]::DynamicConfig<rustc_query_system[8ca381065095edd4]::query::caches::SingleCache<rustc_middle[2dc3a1ceabbabe6a]::query::erase::Erased<[u8; 0usize]>>, false, false, false>, rustc_query_impl[ad69a23e50a8fbd1]::plumbing::QueryCtxt, false>
  34:     0x7f16ca7fb438 - rustc_query_impl[ad69a23e50a8fbd1]::query_impl::analysis::get_query_non_incr::__rust_end_short_backtrace
  35:     0x7f16cab1b47e - rustc_interface[f2198cb0de4afffb]::passes::create_and_enter_global_ctxt::<core[e6c01ae462af1362]::option::Option<rustc_interface[f2198cb0de4afffb]::queries::Linker>, rustc_driver_impl[261694032873b461]::run_compiler::{closure#0}::{closure#2}>::{closure#2}::{closure#0}
  36:     0x7f16ca90d904 - rustc_interface[f2198cb0de4afffb]::interface::run_compiler::<(), rustc_driver_impl[261694032873b461]::run_compiler::{closure#0}>::{closure#1}
  37:     0x7f16ca6ee028 - std[6f1f62f9e1890267]::sys::backtrace::__rust_begin_short_backtrace::<rustc_interface[f2198cb0de4afffb]::util::run_in_thread_with_globals<rustc_interface[f2198cb0de4afffb]::util::run_in_thread_pool_with_globals<rustc_interface[f2198cb0de4afffb]::interface::run_compiler<(), rustc_driver_impl[261694032873b461]::run_compiler::{closure#0}>::{closure#1}, ()>::{closure#0}, ()>::{closure#0}::{closure#0}, ()>
  38:     0x7f16ca6ee92b - <<std[6f1f62f9e1890267]::thread::Builder>::spawn_unchecked_<rustc_interface[f2198cb0de4afffb]::util::run_in_thread_with_globals<rustc_interface[f2198cb0de4afffb]::util::run_in_thread_pool_with_globals<rustc_interface[f2198cb0de4afffb]::interface::run_compiler<(), rustc_driver_impl[261694032873b461]::run_compiler::{closure#0}>::{closure#1}, ()>::{closure#0}, ()>::{closure#0}::{closure#0}, ()>::{closure#1} as core[e6c01ae462af1362]::ops::function::FnOnce<()>>::call_once::{shim:vtable#0}
  39:     0x7f16ca6efd37 - std::sys::pal::unix::thread::Thread::new::thread_start::he9943a285b1830ff
  40:     0x7f16c46a370a - <unknown>
  41:     0x7f16c4727aac - <unknown>
  42:                0x0 - <unknown>

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

note: rustc 1.88.0-nightly (40dacd50b 2025-04-15) running on x86_64-unknown-linux-gnu

note: compiler flags: -Z mir-opt-level=5 -Z validate-mir -Z dump-mir-dir=dir

query stack during panic:
#0 [optimized_mir] optimizing MIR for `main`
#1 [analysis] running analysis passes on this crate
end of query stack
error: aborting due to 2 previous errors; 1 warning emitted

For more information about this error, try `rustc --explain E0277`.

[matthiaskrgr]

bisects to nightly-2024-08-09
commit[0] 2024-08-07: Auto merge of #128796 - matthiaskrgr:rollup-r7l68ph, r=matthiaskrgr
commit[1] 2024-08-07: Auto merge of #128793 - matthiaskrgr:rollup-ork16t0, r=matthiaskrgr
commit[2] 2024-08-08: Auto merge of #128550 - compiler-errors:shadowed-params-perf, r=petrochenkov
commit[3] 2024-08-08: Auto merge of #128805 - tgross35:rollup-wajzi6w, r=tgross35
commit[4] 2024-08-08: Auto merge of #128465 - GrigorenkoPV:128200, r=estebank
commit[5] 2024-08-08: Auto merge of #128639 - folkertdev:rmake-thumb-none-qemu, r=jieyouxu
commit[6] 2024-08-08: Auto merge of #128835 - matthiaskrgr:rollup-apzlbxy, r=matthiaskrgr

[matthiaskrgr]

smaller:

pub fn main() {
    enum A {
        B(u32),
    }
    static C: (A, u16, str);
    fn d() {
        let (_, e, _) = C;
    }
}

``

[meithecatte]

It seems that the issue is that mir opts are running even though errors have been encountered.

[meithecatte]

The ICE got introduced in #128612.

@compiler-errors would you agree that -Zvalidate-mir shouldn't force the MIR when errors have been emitted?

[compiler-errors]

Not necessarily. -Zvalidate-mir not computing running on any bodies if one has errors emitted seems like a very large hammer.

My initial reaction is also that I think this problem is deeper than -Zvalidate-mir. This ICE would happen any time you can get CTFE to try to evaluate C, which can happen for a number of reasons, and using C in a body doesn't necessarily taint that body b/c it's the C item's responsibility to ensure that it's well-formed -- other bodies aren't e.g. enforcing that it's sized or anything.

This is generally the problem with evaluating any const in a type system where one item can make assumptions that other items have proven that they are well-formed (and thus don't need to prove their callee/referencee's well-formedness).