ICE: assertion `left == right` failed: `non-Aggregate field with matching ABI but differing alignment`

[cushionbadak]

Code

(reduced)

#[repr(packed)]
#[repr(u32)]
enum E {
    A,
    B,
    C,
}

fn main() {
    union InvalidTag {
        int: u32,
        e: E,
    }
    let _invalid_tag = InvalidTag { int: 4 };
}

Original Code

//@ run-pass
use std::mem;

#[repr(packed)]
// skip-filecheck
//@ unit-test: GVN
//@ compile-flags: -Zmir-enable-passes=+RemoveZsts
// Verify that we can pretty print invalid constants.

#![feature(adt_const_params)]
#![feature(inline_const)]
#![allow(incomplete_features)]

#[derive(Copy, Clone)]
#[repr(u32)]
enum E { A, B, C }

#[derive(Copy, Clone)]
enum Empty {}

// EMIT_MIR invalid_constant.main.RemoveZsts.diff
// EMIT_MIR invalid_constant.main.GVN.diff
fn main() {
    // An invalid char.
    union InvalidChar {
        int: u32,
        chr: char,
    }
    let _invalid_char = unsafe { InvalidChar { int: 0x110001 }.chr };

    // An enum with an invalid tag. Regression test for #93688.
    union InvalidTag {
        int: u32,
        e: E,
    }
    let _invalid_tag = [unsafe { InvalidTag { int: 4 }.e }];

    // An enum without variants. Regression test for #94073.
    union NoVariants {
        int: u32,
        empty: Empty,
    }
    let _enum_without_variants = [unsafe { NoVariants { int: 0 }.empty }];

    // A non-UTF-8 string slice. Regression test for #75763 and #78520.
    struct Str<const S: &'static str>;
    let _non_utf8_str: Str::<{
        unsafe { std::mem::transmute::<&[u8], &str>(&[0xC0, 0xC1, 0xF5]) }
    }>;
}

struct S4(u8,[u8; 3]);

#[repr(packed)]
#[allow(dead_code)]
struct S5(u8,u32);

pub fn main() {
    unsafe {
        let s4 = S4(1, [2,3,4]);
        let transd : [u8; 4] = mem::transmute(s4);
        assert_eq!(transd, [1, 2, 3, 4]);

        let s5 = S5(1, 0xff_00_00_ff);
        let transd : [u8; 5] = mem::transmute(s5);
        // Don't worry about endianness, the u32 is palindromic.
        assert_eq!(transd, [1, 0xff, 0, 0, 0xff]);
    }
}

• Above original code is mutated from tests/mir-opt/const_prop/invalid_constant.rs
  • I guess #[repr(packed)] at the top causes ICE

Meta

rustc --version --verbose:

rustc 1.79.0-nightly (8b2459c1f 2024-04-09)
binary: rustc
commit-hash: 8b2459c1f21187f9792d99310171a15e64feb9cf
commit-date: 2024-04-09
host: aarch64-apple-darwin
release: 1.79.0-nightly
LLVM version: 18.1.3

Command

rustc

Error output

error[E0517]: attribute should be applied to a struct or union
 --> r_3D5934B8.rs:1:8
  |
1 |   #[repr(packed)]
  |          ^^^^^^
2 |   #[repr(u32)]
3 | / enum E {
4 | |     A,
5 | |     B,
6 | |     C,
7 | | }
  | |_- not a struct or union

error[E0740]: field must implement `Copy` or be wrapped in `ManuallyDrop<...>` to be used in a union
  --> r_3D5934B8.rs:12:9
   |
12 |         e: E,
   |         ^^^^
   |
   = note: union fields must not have drop side-effects, which is currently enforced via either `Copy` or `ManuallyDrop<...>`
help: wrap the field type in `ManuallyDrop<...>`
   |
12 |         e: std::mem::ManuallyDrop<E>,
   |            +++++++++++++++++++++++ +

Backtrace

thread 'rustc' panicked at /rustc/8b2459c1f21187f9792d99310171a15e64feb9cf/compiler/rustc_abi/src/layout.rs:289:29:
assertion `left == right` failed: non-Aggregate field with matching ABI but differing alignment
  left: Align(4 bytes)
 right: Align(1 bytes)
stack backtrace:
   0: _rust_begin_unwind
   1: core::panicking::panic_fmt
   2: core::panicking::assert_failed_inner
   3: core::panicking::assert_failed::<rustc_abi::Align, rustc_abi::Align>
   4: <rustc_middle::ty::layout::LayoutCx<rustc_middle::ty::context::TyCtxt> as rustc_abi::layout::LayoutCalculator>::layout_of_union::<rustc_target::abi::FieldIdx, rustc_target::abi::VariantIdx, rustc_target::abi::Layout>
   5: rustc_ty_utils::layout::layout_of_uncached
   6: rustc_ty_utils::layout::layout_of
      [... omitted 2 frames ...]
   7: rustc_middle::query::plumbing::query_get_at::<rustc_query_system::query::caches::DefaultCache<rustc_middle::ty::ParamEnvAnd<rustc_middle::ty::Ty>, rustc_middle::query::erase::Erased<[u8; 16]>>>
   8: <rustc_mir_transform::known_panics_lint::KnownPanicsLint as rustc_mir_transform::pass_manager::MirLint>::run_lint
   9: rustc_mir_transform::pass_manager::run_passes_inner
  10: rustc_mir_transform::run_analysis_to_runtime_passes
  11: rustc_mir_transform::mir_drops_elaborated_and_const_checked
      [... omitted 2 frames ...]
  12: <rustc_session::session::Session>::time::<(), rustc_interface::passes::run_required_analyses::{closure#2}>
  13: rustc_interface::passes::analysis
      [... omitted 2 frames ...]
  14: <rustc_middle::ty::context::GlobalCtxt>::enter::<rustc_driver_impl::run_compiler::{closure#0}::{closure#1}::{closure#3}, core::result::Result<(), rustc_span::ErrorGuaranteed>>
  15: <rustc_interface::interface::Compiler>::enter::<rustc_driver_impl::run_compiler::{closure#0}::{closure#1}, core::result::Result<core::option::Option<rustc_interface::queries::Linker>, rustc_span::ErrorGuaranteed>>
  16: rustc_span::set_source_map::<core::result::Result<(), rustc_span::ErrorGuaranteed>, rustc_interface::interface::run_compiler<core::result::Result<(), rustc_span::ErrorGuaranteed>, rustc_driver_impl::run_compiler::{closure#0}>::{closure#0}::{closure#0}>
  17: <scoped_tls::ScopedKey<rustc_span::SessionGlobals>>::set::<rustc_interface::util::run_in_thread_with_globals<rustc_interface::util::run_in_thread_pool_with_globals<rustc_interface::interface::run_compiler<core::result::Result<(), rustc_span::ErrorGuaranteed>, rustc_driver_impl::run_compiler::{closure#0}>::{closure#0}, core::result::Result<(), rustc_span::ErrorGuaranteed>>::{closure#0}, core::result::Result<(), rustc_span::ErrorGuaranteed>>::{closure#0}::{closure#0}::{closure#0}, core::result::Result<(), rustc_span::ErrorGuaranteed>>
  18: rustc_span::create_session_globals_then::<core::result::Result<(), rustc_span::ErrorGuaranteed>, rustc_interface::util::run_in_thread_with_globals<rustc_interface::util::run_in_thread_pool_with_globals<rustc_interface::interface::run_compiler<core::result::Result<(), rustc_span::ErrorGuaranteed>, rustc_driver_impl::run_compiler::{closure#0}>::{closure#0}, core::result::Result<(), rustc_span::ErrorGuaranteed>>::{closure#0}, core::result::Result<(), rustc_span::ErrorGuaranteed>>::{closure#0}::{closure#0}::{closure#0}>
note: Some details are omitted, run with `RUST_BACKTRACE=full` for a verbose backtrace.

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 attach the file at `/Users/jisukbyun/workspace/placeholder/0409_rust/rustc-ice-2024-04-10T04_21_59-38944.txt` to your bug report

query stack during panic:
#0 [layout_of] computing layout of `main::InvalidTag`
#1 [mir_drops_elaborated_and_const_checked] elaborating drops for `main`
#2 [analysis] running analysis passes on this crate
end of query stack
error: aborting due to 2 previous errors

Some errors have detailed explanations: E0517, E0740.
For more information about an error, try `rustc --explain E0517`.

Note

• ICE occurred at rustc_abi/src/layout.rs Line-289
  

  rust/compiler/rustc_abi/src/layout.rs

  Lines 277 to 300 in 8b2459c

  	if let Ok(common) = common_non_zst_abi_and_align {
  	// Discard valid range information and allow undef
  	let field_abi = field.abi.to_union();
  	if let Some((common_abi, common_align)) = common {
  	if common_abi != field_abi {
  	// Different fields have different ABI: disable opt
  	common_non_zst_abi_and_align = Err(AbiMismatch);
  	} else {
  	// Fields with the same non-Aggregate ABI should also
  	// have the same alignment
  	if !matches!(common_abi, Abi::Aggregate { .. }) {
  	assert_eq!(
  	common_align, field.align.abi,
  	"non-Aggregate field with matching ABI but differing alignment"
  	);
  	}
  	}
  	} else {
  	// First non-ZST field: record its ABI and alignment
  	common_non_zst_abi_and_align = Ok(Some((field_abi, field.align.abi)));
  	}
  	}
  	}

[eggyal]

@rustbot label regression-from-stable-to-beta

[eggyal]

searched nightlies: from nightly-2024-02-01 to nightly-2024-04-10
regressed nightly: nightly-2024-02-09
searched commit range: 8ace7ea...98aa362
regressed commit: af88f7d

bisected with cargo-bisect-rustc v0.6.7

Host triple: aarch64-unknown-linux-gnu
Reproduce with:

cargo bisect-rustc --regress ice --start 1.77.2 -- build 

cc #120550 @oli-obk

[apiraino]

WG-prioritization assigning priority (Zulip discussion).

@rustbot label -I-prioritize +P-medium