[ICE]: `not immediate: OperandRef`

[matthiaskrgr]

auto-reduced (treereduce-rust):

//@compile-flags: --crate-type=lib
#![feature(never_type)]
pub fn invoke(pc_section: &[!]) {
    unsafe { std::arch::asm!("/* {} */", in(reg)pc_section[0]) }
}

original:

#![feature(never_type)]
pub fn invoke(pc_section: &[!]) {
    unsafe { std::arch::asm!("/* {} */", in(reg)pc_section[0]) }
}

fn main() {}

Version information

rustc 1.96.0-nightly (fff9e4432 2026-04-06)
binary: rustc
commit-hash: fff9e4432233df859e4fadb30ab7f0eda22580a6
commit-date: 2026-04-06
host: x86_64-unknown-linux-gnu
release: 1.96.0-nightly
LLVM version: 22.1.2

Possibly related line of code:

rust/compiler/rustc_codegen_ssa/src/mir/operand.rs

Lines 255 to 267 in fff9e44

	/// Asserts that this operand refers to a scalar and returns
	/// a reference to its value.
	pub fn immediate(self) -> V {
	match self.val {
	OperandValue::Immediate(s) => s,
	_ => bug!("not immediate: {:?}", self),
	}
	}
	/// Asserts that this operand is a pointer (or reference) and returns
	/// the place to which it points. (This requires no code to be emitted
	/// as we represent places using the pointer to the place.)

Command:
/home/matthias/.rustup/toolchains/master/bin/rustc --crate-type=lib

Program output

warning: unreachable expression
 --> /tmp/icemaker_global_tempdir.5Evymrx7HUWq/rustc_testrunner_tmpdir_reporting.0uNSLS5yKoU9/mvce.rs:3:14
  |
3 |     unsafe { std::arch::asm!("/* {} */", in(reg)pc_section[0]) }
  |              ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^-------------^
  |              |                                  |
  |              |                                  any code following this expression is unreachable
  |              unreachable expression
  |
  = note: `#[warn(unreachable_code)]` (part of `#[warn(unused)]`) on by default

error: internal compiler error: /rustc-dev/fff9e4432233df859e4fadb30ab7f0eda22580a6/compiler/rustc_codegen_ssa/src/mir/operand.rs:261:18: not immediate: OperandRef(ZeroSized @ TyAndLayout { ty: !, layout: Layout { size: Size(0 bytes), align: AbiAlign { abi: Align(1 bytes) }, backend_repr: Memory { sized: true }, fields: Primitive, largest_niche: None, uninhabited: true, variants: Empty, max_repr_align: None, unadjusted_abi_align: Align(1 bytes), randomization_seed: 0 } })


thread 'rustc' (480724) panicked at /rustc-dev/fff9e4432233df859e4fadb30ab7f0eda22580a6/compiler/rustc_codegen_ssa/src/mir/operand.rs:261:18:
Box<dyn Any>
stack backtrace:
   0:     0x7f9bc6dda35b - <<std[8c96247e38178e87]::sys::backtrace::BacktraceLock>::print::DisplayBacktrace as core[bb53695d08591fa6]::fmt::Display>::fmt
   1:     0x7f9bc741ddc8 - core[bb53695d08591fa6]::fmt::write
   2:     0x7f9bc6df1626 - <std[8c96247e38178e87]::sys::stdio::unix::Stderr as std[8c96247e38178e87]::io::Write>::write_fmt
   3:     0x7f9bc6db0658 - std[8c96247e38178e87]::panicking::default_hook::{closure#0}
   4:     0x7f9bc6dcd9c3 - std[8c96247e38178e87]::panicking::default_hook
   5:     0x7f9bc5dd494c - std[8c96247e38178e87]::panicking::update_hook::<alloc[ccb441010e164770]::boxed::Box<rustc_driver_impl[81e2fde32905c39d]::install_ice_hook::{closure#1}>>::{closure#0}
   6:     0x7f9bc6dcdca2 - std[8c96247e38178e87]::panicking::panic_with_hook
   7:     0x7f9bc5e04921 - std[8c96247e38178e87]::panicking::begin_panic::<rustc_errors[f5d3ddd97d961da3]::ExplicitBug>::{closure#0}
   8:     0x7f9bc5dfd386 - std[8c96247e38178e87]::sys::backtrace::__rust_end_short_backtrace::<std[8c96247e38178e87]::panicking::begin_panic<rustc_errors[f5d3ddd97d961da3]::ExplicitBug>::{closure#0}, !>
   9:     0x7f9bc5dfb188 - std[8c96247e38178e87]::panicking::begin_panic::<rustc_errors[f5d3ddd97d961da3]::ExplicitBug>
  10:     0x7f9bc5e0ff61 - <rustc_errors[f5d3ddd97d961da3]::diagnostic::BugAbort as rustc_errors[f5d3ddd97d961da3]::diagnostic::EmissionGuarantee>::emit_producing_guarantee
  11:     0x7f9bc63ec199 - rustc_middle[6be30f081655eb95]::util::bug::opt_span_bug_fmt::<rustc_span[80bda612cc6ab068]::span_encoding::Span>::{closure#0}
  12:     0x7f9bc63ec322 - rustc_middle[6be30f081655eb95]::ty::context::tls::with_opt::<rustc_middle[6be30f081655eb95]::util::bug::opt_span_bug_fmt<rustc_span[80bda612cc6ab068]::span_encoding::Span>::{closure#0}, !>::{closure#0}
  13:     0x7f9bc63dc8db - rustc_middle[6be30f081655eb95]::ty::context::tls::with_context_opt::<rustc_middle[6be30f081655eb95]::ty::context::tls::with_opt<rustc_middle[6be30f081655eb95]::util::bug::opt_span_bug_fmt<rustc_span[80bda612cc6ab068]::span_encoding::Span>::{closure#0}, !>::{closure#0}, !>
  14:     0x7f9bc350cec4 - rustc_middle[6be30f081655eb95]::util::bug::bug_fmt
  15:     0x7f9bc88874a7 - <rustc_codegen_llvm[9ed2f6cbf1cc5fb8]::builder::GenericBuilder<rustc_codegen_llvm[9ed2f6cbf1cc5fb8]::context::FullCx> as rustc_codegen_ssa[524a24c60837220e]::traits::asm::AsmBuilderMethods>::codegen_inline_asm
  16:     0x7f9bc886b0a7 - rustc_codegen_ssa[524a24c60837220e]::mir::codegen_mir::<rustc_codegen_llvm[9ed2f6cbf1cc5fb8]::builder::GenericBuilder<rustc_codegen_llvm[9ed2f6cbf1cc5fb8]::context::FullCx>>
  17:     0x7f9bc74d855f - rustc_codegen_llvm[9ed2f6cbf1cc5fb8]::base::compile_codegen_unit::module_codegen
  18:     0x7f9bc874d144 - <rustc_codegen_llvm[9ed2f6cbf1cc5fb8]::LlvmCodegenBackend as rustc_codegen_ssa[524a24c60837220e]::traits::backend::ExtraBackendMethods>::compile_codegen_unit
  19:     0x7f9bc8748c87 - rustc_codegen_ssa[524a24c60837220e]::base::codegen_crate::<rustc_codegen_llvm[9ed2f6cbf1cc5fb8]::LlvmCodegenBackend>
  20:     0x7f9bc8746dcd - <rustc_codegen_llvm[9ed2f6cbf1cc5fb8]::LlvmCodegenBackend as rustc_codegen_ssa[524a24c60837220e]::traits::backend::CodegenBackend>::codegen_crate
  21:     0x7f9bc864f9f2 - <rustc_interface[a07b2b9cb0b39108]::queries::Linker>::codegen_and_build_linker
  22:     0x7f9bc8649b97 - rustc_interface[a07b2b9cb0b39108]::interface::run_compiler::<(), rustc_driver_impl[81e2fde32905c39d]::run_compiler::{closure#0}>::{closure#1}
  23:     0x7f9bc862effe - std[8c96247e38178e87]::sys::backtrace::__rust_begin_short_backtrace::<rustc_interface[a07b2b9cb0b39108]::util::run_in_thread_with_globals<rustc_interface[a07b2b9cb0b39108]::util::run_in_thread_pool_with_globals<rustc_interface[a07b2b9cb0b39108]::interface::run_compiler<(), rustc_driver_impl[81e2fde32905c39d]::run_compiler::{closure#0}>::{closure#1}, ()>::{closure#0}, ()>::{closure#0}::{closure#0}, ()>
  24:     0x7f9bc862f8a0 - <std[8c96247e38178e87]::thread::lifecycle::spawn_unchecked<rustc_interface[a07b2b9cb0b39108]::util::run_in_thread_with_globals<rustc_interface[a07b2b9cb0b39108]::util::run_in_thread_pool_with_globals<rustc_interface[a07b2b9cb0b39108]::interface::run_compiler<(), rustc_driver_impl[81e2fde32905c39d]::run_compiler::{closure#0}>::{closure#1}, ()>::{closure#0}, ()>::{closure#0}::{closure#0}, ()>::{closure#1} as core[bb53695d08591fa6]::ops::function::FnOnce<()>>::call_once::{shim:vtable#0}
  25:     0x7f9bc86307ac - <std[8c96247e38178e87]::sys::thread::unix::Thread>::new::thread_start
  26:     0x7f9bc20a597a - <unknown>
  27:     0x7f9bc21292bc - <unknown>
  28:                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 1.96.0-nightly (fff9e4432 2026-04-06) running on x86_64-unknown-linux-gnu

note: compiler flags: --crate-type lib -Z dump-mir-dir=dir

query stack during panic:
end of query stack
error: aborting due to 1 previous error; 1 warning emitted

@rustbot label +F-never_type

[matthiaskrgr]

this is a modification of tests/ui/asm/normalizable-asm-ty.rs passing pc_section: &[!] instead of pc_section: &[usize]

[matthiaskrgr]

since nightly-2025-04-30

  commit[0] 2025-04-28: Auto merge of #140388 - GuillaumeGomez:rollup-aj9o3ch, r=GuillaumeGomez
  commit[1] 2025-04-29: Auto merge of #140415 - ChrisDenton:rollup-r0631fv, r=ChrisDenton
  commit[2] 2025-04-29: Auto merge of #137940 - 1c3t3a:alignment-borrows-check, r=saethlin
  commit[3] 2025-04-29: Auto merge of #140436 - RalfJung:miri-sync, r=RalfJung
  commit[4] 2025-04-29: Auto merge of #140474 - tgross35:rollup-rdkao89, r=tgross35

[matthiaskrgr]

no longer needs any feature gates after #155499

#![crate_type="lib"]
pub fn invoke(pc_section: &[!]) {
    unsafe { std::arch::asm!("/* {} */", in(reg)pc_section[0]) }
}

[zachs18]

@rustbot claim