ICE: `non-Aggregate field with matching ABI but differing alignment`

matthiaskrgr commented 1 week ago

auto-reduced (treereduce-rust):

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

    pub fn is_transmutable<Src, Dst>()
    where
        Dst: BikeshedIntrinsicFrom<Src>,
    {
    }
}

#[repr(u32)]
enum Ox00 {
    V = 0x00,
}
enum Ox01 {
    V = 0x01,
}
#[repr(C, packed(2))]
enum OxFF {
    V = 0xFF,
}

fn test() {
    #[derive]

    union Superset {
        a: Ox00,
        b: OxFF,
        b: Ox01,
    }

    assert::is_transmutable::<Superset, Subset>();
}

original:

#![crate_type = "lib"]
#![feature(allow)]
#![allow(dead_code, incomplete_features, non_camel_case_types)]

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

    pub fn is_transmutable<Src, Dst>()
    where
        Dst: BikeshedIntrinsicFrom<Src, { Assume::SAFETY.and(Assume::VALIDITY) }>
    {}
}

#[derive(Clone, Copy)] #[repr(u32)] enum Ox00 { V = 0x00 }
#[derive(Clone, Copy)] #[repr(u8)] enum Ox01 { V = 0x01 }
#[derive(Clone, Copy)] #[repr(C, packed(2))] enum OxFF { V = 0xFF }

fn test() {
    #[derive]
    union Subset {
        a: (),
        b: V1u8,
    }

    #[packed(C)]
    union Superset {
        a: Ox00,
        b: OxFF,
        b: Ox01,
    }

    assert::is_transmutable::<Superset, Subset>(); //~ ERROR cannot be safely transmuted
}

Version information

rustc 1.81.0-nightly (d929a42a6 2024-06-25)
binary: rustc
commit-hash: d929a42a664c026167800801b26d734db925314f
commit-date: 2024-06-25
host: x86_64-unknown-linux-gnu
release: 1.81.0-nightly
LLVM version: 18.1.7

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

Program output

``` error: malformed `derive` attribute input --> /tmp/icemaker_global_tempdir.WonAMZI2vcAF/rustc_testrunner_tmpdir_reporting.xuyJdDymg62q/mvce.rs:24:5 | 24 | #[derive] | ^^^^^^^^^ help: must be of the form: `#[derive(Trait1, Trait2, ...)]` error[E0412]: cannot find type `Subset` in this scope --> /tmp/icemaker_global_tempdir.WonAMZI2vcAF/rustc_testrunner_tmpdir_reporting.xuyJdDymg62q/mvce.rs:32:41 | 32 | assert::is_transmutable::(); | ^^^^^^ not found in this scope | help: you might be missing a type parameter | 23 | fn test() { | ++++++++ warning: unused import: `Assume` --> /tmp/icemaker_global_tempdir.WonAMZI2vcAF/rustc_testrunner_tmpdir_reporting.xuyJdDymg62q/mvce.rs:2:20 | 2 | use std::mem::{Assume, BikeshedIntrinsicFrom}; | ^^^^^^ | = note: `#[warn(unused_imports)]` on by default error[E0601]: `main` function not found in crate `mvce` --> /tmp/icemaker_global_tempdir.WonAMZI2vcAF/rustc_testrunner_tmpdir_reporting.xuyJdDymg62q/mvce.rs:33:2 | 33 | } | ^ consider adding a `main` function to `/tmp/icemaker_global_tempdir.WonAMZI2vcAF/rustc_testrunner_tmpdir_reporting.xuyJdDymg62q/mvce.rs` error[E0517]: attribute should be applied to a struct or union --> /tmp/icemaker_global_tempdir.WonAMZI2vcAF/rustc_testrunner_tmpdir_reporting.xuyJdDymg62q/mvce.rs:18:11 | 18 | #[repr(C, packed(2))] | ^^^^^^^^^ 19 | / enum OxFF { 20 | | V = 0xFF, 21 | | } | |_- not a struct or union error[E0658]: use of unstable library feature 'transmutability' --> /tmp/icemaker_global_tempdir.WonAMZI2vcAF/rustc_testrunner_tmpdir_reporting.xuyJdDymg62q/mvce.rs:2:20 | 2 | use std::mem::{Assume, BikeshedIntrinsicFrom}; | ^^^^^^ | = note: see issue #99571 for more information = help: add `#![feature(transmutability)]` to the crate attributes to enable = note: this compiler was built on 2024-06-25; consider upgrading it if it is out of date error[E0658]: use of unstable library feature 'transmutability' --> /tmp/icemaker_global_tempdir.WonAMZI2vcAF/rustc_testrunner_tmpdir_reporting.xuyJdDymg62q/mvce.rs:2:28 | 2 | use std::mem::{Assume, BikeshedIntrinsicFrom}; | ^^^^^^^^^^^^^^^^^^^^^ | = note: see issue #99571 for more information = help: add `#![feature(transmutability)]` to the crate attributes to enable = note: this compiler was built on 2024-06-25; consider upgrading it if it is out of date error[E0658]: use of unstable library feature 'transmutability' --> /tmp/icemaker_global_tempdir.WonAMZI2vcAF/rustc_testrunner_tmpdir_reporting.xuyJdDymg62q/mvce.rs:6:14 | 6 | Dst: BikeshedIntrinsicFrom, | ^^^^^^^^^^^^^^^^^^^^^^^^^^ | = note: see issue #99571 for more information = help: add `#![feature(transmutability)]` to the crate attributes to enable = note: this compiler was built on 2024-06-25; consider upgrading it if it is out of date error[E0124]: field `b` is already declared --> /tmp/icemaker_global_tempdir.WonAMZI2vcAF/rustc_testrunner_tmpdir_reporting.xuyJdDymg62q/mvce.rs:29:9 | 28 | b: OxFF, | ------- `b` first declared here 29 | b: Ox01, | ^^^^^^^ field already declared error[E0740]: field must implement `Copy` or be wrapped in `ManuallyDrop<...>` to be used in a union --> /tmp/icemaker_global_tempdir.WonAMZI2vcAF/rustc_testrunner_tmpdir_reporting.xuyJdDymg62q/mvce.rs:27:9 | 27 | a: Ox00, | ^^^^^^^ | = 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<...>` | 27 | a: std::mem::ManuallyDrop, | +++++++++++++++++++++++ + thread 'rustc' panicked at /rustc/d929a42a664c026167800801b26d734db925314f/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(2 bytes) stack backtrace: 0: 0x777bc94142e5 - std::backtrace_rs::backtrace::libunwind::trace::h3816f17667167091 at /rustc/d929a42a664c026167800801b26d734db925314f/library/std/src/../../backtrace/src/backtrace/libunwind.rs:116:5 1: 0x777bc94142e5 - std::backtrace_rs::backtrace::trace_unsynchronized::h05c1a74390e79138 at /rustc/d929a42a664c026167800801b26d734db925314f/library/std/src/../../backtrace/src/backtrace/mod.rs:66:5 2: 0x777bc94142e5 - std::sys::backtrace::_print_fmt::hf9f67f450e2340b3 at /rustc/d929a42a664c026167800801b26d734db925314f/library/std/src/sys/backtrace.rs:68:5 3: 0x777bc94142e5 - ::fmt::hd0470f4740d6f066 at /rustc/d929a42a664c026167800801b26d734db925314f/library/std/src/sys/backtrace.rs:44:22 4: 0x777bc9463ceb - core::fmt::rt::Argument::fmt::h70b8a6b09781c530 at /rustc/d929a42a664c026167800801b26d734db925314f/library/core/src/fmt/rt.rs:165:63 5: 0x777bc9463ceb - core::fmt::write::hafea0839d2bbb3f2 at /rustc/d929a42a664c026167800801b26d734db925314f/library/core/src/fmt/mod.rs:1168:21 6: 0x777bc9408f6f - std::io::Write::write_fmt::h781fa7911c53c2fa at /rustc/d929a42a664c026167800801b26d734db925314f/library/std/src/io/mod.rs:1835:15 7: 0x777bc94140be - std::sys::backtrace::_print::h864675b81ca0e917 at /rustc/d929a42a664c026167800801b26d734db925314f/library/std/src/sys/backtrace.rs:47:5 8: 0x777bc94140be - std::sys::backtrace::print::h077604854516c949 at /rustc/d929a42a664c026167800801b26d734db925314f/library/std/src/sys/backtrace.rs:34:9 9: 0x777bc9416a09 - std::panicking::default_hook::{{closure}}::h0655bbcac1b3559e 10: 0x777bc94167ac - std::panicking::default_hook::ha9e013cc76e074dd at /rustc/d929a42a664c026167800801b26d734db925314f/library/std/src/panicking.rs:292:9 11: 0x777bc59eac90 - std[e6dd88f179d4d596]::panicking::update_hook::>::{closure#0} 12: 0x777bc94172df - as core::ops::function::Fn>::call::haac7baf64299a07d at /rustc/d929a42a664c026167800801b26d734db925314f/library/alloc/src/boxed.rs:2078:9 13: 0x777bc94172df - std::panicking::rust_panic_with_hook::h9bfa469549e655b8 at /rustc/d929a42a664c026167800801b26d734db925314f/library/std/src/panicking.rs:804:13 14: 0x777bc9416f07 - std::panicking::begin_panic_handler::{{closure}}::h4a967f6ef7ab4640 at /rustc/d929a42a664c026167800801b26d734db925314f/library/std/src/panicking.rs:670:13 15: 0x777bc94147a9 - std::sys::backtrace::__rust_end_short_backtrace::h6bde84250dc9cd8b at /rustc/d929a42a664c026167800801b26d734db925314f/library/std/src/sys/backtrace.rs:171:18 16: 0x777bc9416be4 - rust_begin_unwind at /rustc/d929a42a664c026167800801b26d734db925314f/library/std/src/panicking.rs:661:5 17: 0x777bc94602a3 - core::panicking::panic_fmt::h036234c821d91466 at /rustc/d929a42a664c026167800801b26d734db925314f/library/core/src/panicking.rs:74:14 18: 0x777bc946087f - core::panicking::assert_failed_inner::h6886c5ce8b27c112 at /rustc/d929a42a664c026167800801b26d734db925314f/library/core/src/panicking.rs:405:23 19: 0x777bc6742f17 - core[672c7616ff9a88f5]::panicking::assert_failed:: 20: 0x777bc775ea4e - rustc_ty_utils[91a81cae3f51d4c]::layout::layout_of_uncached 21: 0x777bc774ce0b - rustc_ty_utils[91a81cae3f51d4c]::layout::layout_of 22: 0x777bc774cd91 - rustc_query_impl[b034b92d40b1d47d]::plumbing::__rust_begin_short_backtrace::> 23: 0x777bc774c0b6 - rustc_query_system[4a94863d7e85f976]::query::plumbing::try_execute_query::, rustc_middle[e321b4b4f2134162]::query::erase::Erased<[u8; 16usize]>>, false, true, false>, rustc_query_impl[b034b92d40b1d47d]::plumbing::QueryCtxt, false> 24: 0x777bc774bd45 - rustc_query_impl[b034b92d40b1d47d]::query_impl::layout_of::get_query_non_incr::__rust_end_short_backtrace 25: 0x777bc671d5cc - rustc_middle[e321b4b4f2134162]::query::plumbing::query_get_at::, rustc_middle[e321b4b4f2134162]::query::erase::Erased<[u8; 16usize]>>> 26: 0x777bc6734531 - ::is_transmutable 27: 0x777bc79db58f - ::confirm_candidate 28: 0x777bc7472f11 - ::evaluate_trait_predicate_recursively 29: 0x777bc746ce97 - ::evaluate_root_obligation 30: 0x777bc746b215 - rustc_traits[8a90ea068024d15f]::evaluate_obligation::evaluate_obligation 31: 0x777bc746aba9 - rustc_query_impl[b034b92d40b1d47d]::plumbing::__rust_begin_short_backtrace::> 32: 0x777bc746a10f - rustc_query_system[4a94863d7e85f976]::query::plumbing::try_execute_query::>, rustc_middle[e321b4b4f2134162]::query::erase::Erased<[u8; 2usize]>>, false, false, false>, rustc_query_impl[b034b92d40b1d47d]::plumbing::QueryCtxt, false> 33: 0x777bc7469d64 - rustc_query_impl[b034b92d40b1d47d]::query_impl::evaluate_obligation::get_query_non_incr::__rust_end_short_backtrace 34: 0x777bc38caa92 - ::process_obligation 35: 0x777bc70081e7 - >::process_obligations:: 36: 0x777bc3bbbfea - ::confirm_builtin_call 37: 0x777bc7bb4c5d - ::check_expr_with_expectation_and_args 38: 0x777bc7baedf6 - ::check_block_with_expected 39: 0x777bc7bb5760 - ::check_expr_with_expectation_and_args 40: 0x777bc72f91f6 - rustc_hir_typeck[673ed4476fae1319]::check::check_fn 41: 0x777bc72ed054 - rustc_hir_typeck[673ed4476fae1319]::typeck 42: 0x777bc72eca9d - rustc_query_impl[b034b92d40b1d47d]::plumbing::__rust_begin_short_backtrace::> 43: 0x777bc736a073 - rustc_query_system[4a94863d7e85f976]::query::plumbing::try_execute_query::>, false, false, false>, rustc_query_impl[b034b92d40b1d47d]::plumbing::QueryCtxt, false> 44: 0x777bc736924d - rustc_query_impl[b034b92d40b1d47d]::query_impl::typeck::get_query_non_incr::__rust_end_short_backtrace 45: 0x777bc7368e44 - ::par_body_owners::::{closure#0} 46: 0x777bc73671c1 - rustc_hir_analysis[6239ffc5e5ec24c9]::check_crate 47: 0x777bc735cf15 - rustc_interface[73bd107be0165211]::passes::analysis 48: 0x777bc735cad9 - rustc_query_impl[b034b92d40b1d47d]::plumbing::__rust_begin_short_backtrace::> 49: 0x777bc7e50825 - rustc_query_system[4a94863d7e85f976]::query::plumbing::try_execute_query::>, false, false, false>, rustc_query_impl[b034b92d40b1d47d]::plumbing::QueryCtxt, false> 50: 0x777bc7e5058f - rustc_query_impl[b034b92d40b1d47d]::query_impl::analysis::get_query_non_incr::__rust_end_short_backtrace 51: 0x777bc7d77e3f - rustc_interface[73bd107be0165211]::interface::run_compiler::, rustc_driver_impl[6d6094f07793e4a9]::run_compiler::{closure#0}>::{closure#1} 52: 0x777bc7c37e89 - std[e6dd88f179d4d596]::sys::backtrace::__rust_begin_short_backtrace::, rustc_driver_impl[6d6094f07793e4a9]::run_compiler::{closure#0}>::{closure#1}, core[672c7616ff9a88f5]::result::Result<(), rustc_span[31538c27a715cd64]::ErrorGuaranteed>>::{closure#0}, core[672c7616ff9a88f5]::result::Result<(), rustc_span[31538c27a715cd64]::ErrorGuaranteed>>::{closure#0}::{closure#0}, core[672c7616ff9a88f5]::result::Result<(), rustc_span[31538c27a715cd64]::ErrorGuaranteed>> 53: 0x777bc7c37c3a - <::spawn_unchecked_, rustc_driver_impl[6d6094f07793e4a9]::run_compiler::{closure#0}>::{closure#1}, core[672c7616ff9a88f5]::result::Result<(), rustc_span[31538c27a715cd64]::ErrorGuaranteed>>::{closure#0}, core[672c7616ff9a88f5]::result::Result<(), rustc_span[31538c27a715cd64]::ErrorGuaranteed>>::{closure#0}::{closure#0}, core[672c7616ff9a88f5]::result::Result<(), rustc_span[31538c27a715cd64]::ErrorGuaranteed>>::{closure#2} as core[672c7616ff9a88f5]::ops::function::FnOnce<()>>::call_once::{shim:vtable#0} 54: 0x777bc942116b - as core::ops::function::FnOnce>::call_once::hcfcb27dcb2ebeeb7 at /rustc/d929a42a664c026167800801b26d734db925314f/library/alloc/src/boxed.rs:2064:9 55: 0x777bc942116b - as core::ops::function::FnOnce>::call_once::h7d3cd9c06edd61cc at /rustc/d929a42a664c026167800801b26d734db925314f/library/alloc/src/boxed.rs:2064:9 56: 0x777bc942116b - std::sys::pal::unix::thread::Thread::new::thread_start::h082ffbd0fcdeae0d at /rustc/d929a42a664c026167800801b26d734db925314f/library/std/src/sys/pal/unix/thread.rs:108:17 57: 0x777bc24a6ded - 58: 0x777bc252a0dc - 59: 0x0 - 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 1.81.0-nightly (d929a42a6 2024-06-25) running on x86_64-unknown-linux-gnu query stack during panic: #0 [layout_of] computing layout of `test::Superset` #1 [evaluate_obligation] evaluating trait selection obligation `{type error}: core::mem::transmutability::BikeshedIntrinsicFrom` end of query stack error: aborting due to 9 previous errors; 1 warning emitted Some errors have detailed explanations: E0124, E0412, E0517, E0601, E0658, E0740. For more information about an error, try `rustc --explain E0124`. ```

@rustbot label +F-allow

matthiaskrgr commented 1 week ago

bisects to #123367 cc @jswrenn

matthiaskrgr commented 1 week ago

bit smaller

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

    pub fn is_transmutable<Src, Dst>()
    where
        Dst: BikeshedIntrinsicFrom<Src>,
    {
    }
}

#[repr(u32)]
enum Ox00 {
    V = 0x00,
}

#[repr(C, packed(2))]
enum OxFF {
    V = 0xFF,
}

fn test() {
    union Superset {
        a: Ox00,
        b: OxFF,
    }

    assert::is_transmutable::<Superset, Subset>();
}

rust-lang / rust

ICE: `non-Aggregate field with matching ABI but differing alignment` #126966