ICE `expect Adt for unnamed field`

[matthiaskrgr]

auto-reduced (treereduce-rust):

#[repr(C)]
#[repr(C)]
#[derive(Debug)]
struct L {
    _: i32,
    _: MyI32,
    _: BadEnum,
}

original code

original:

//@ aux-build:dep.rs

// test for #121151

#![allow(incomplete_features)]
#![feature(unnamed_fields)]

extern crate dep;

#[repr(C)]
struct A {
    a: u8,
}

enum BadEnum {
    A,
    B,
}

#[repr(C)]
enum BadEnum2 {
    A,
    B,
}

type MyStruct = A;
type MyI32 = i32;

#[derive(Debug)]
struct L {
    _: i32, //~ ERROR unnamed fields can only have struct or union types
    _: MyI32, //~ ERROR unnamed fields can only have struct or union types
    _: BadEnum, //~ ERROR unnamed fields can only have struct or union types
    _: BadEnum2, //~ ERROR unnamed fields can only have struct or union types
    _: MyStruct,
    _: dep::BadStruct, //~ ERROR named type of unnamed field must have `#[repr(C)]` representation
    _: dep::BadEnum, //~ ERROR unnamed fields can only have struct or union types
    _: dep::BadEnum2, //~ ERROR unnamed fields can only have struct or union types
    _: dep::BadAlias, //~ ERROR unnamed fields can only have struct or union types
    _: dep::GoodAlias,
    _: dep::GoodStruct,
}

fn main() {}

Version information

rustc 1.78.0-nightly (23a3d777c 2024-02-18)
binary: rustc
commit-hash: 23a3d777c8a95715977608c827de63e7738fa228
commit-date: 2024-02-18
host: x86_64-unknown-linux-gnu
release: 1.78.0-nightly
LLVM version: 18.1.0

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

Program output

error[E0412]: cannot find type `MyI32` in this scope
 --> /tmp/icemaker_global_tempdir.ARGn7VxzHBhS/rustc_testrunner_tmpdir_reporting.hJYasVkFeKoS/mvce.rs:6:8
  |
6 |     _: MyI32,
  |        ^^^^^ not found in this scope

error[E0412]: cannot find type `BadEnum` in this scope
 --> /tmp/icemaker_global_tempdir.ARGn7VxzHBhS/rustc_testrunner_tmpdir_reporting.hJYasVkFeKoS/mvce.rs:7:8
  |
7 |     _: BadEnum,
  |        ^^^^^^^ not found in this scope

error[E0658]: unnamed fields are not yet fully implemented
 --> /tmp/icemaker_global_tempdir.ARGn7VxzHBhS/rustc_testrunner_tmpdir_reporting.hJYasVkFeKoS/mvce.rs:5:5
  |
5 |     _: i32,
  |     ^
  |
  = note: see issue #49804 <https://github.com/rust-lang/rust/issues/49804> for more information
  = help: add `#![feature(unnamed_fields)]` to the crate attributes to enable
  = note: this compiler was built on 2024-02-18; consider upgrading it if it is out of date

error[E0658]: unnamed fields are not yet fully implemented
 --> /tmp/icemaker_global_tempdir.ARGn7VxzHBhS/rustc_testrunner_tmpdir_reporting.hJYasVkFeKoS/mvce.rs:6:5
  |
6 |     _: MyI32,
  |     ^
  |
  = note: see issue #49804 <https://github.com/rust-lang/rust/issues/49804> for more information
  = help: add `#![feature(unnamed_fields)]` to the crate attributes to enable
  = note: this compiler was built on 2024-02-18; consider upgrading it if it is out of date

error[E0658]: unnamed fields are not yet fully implemented
 --> /tmp/icemaker_global_tempdir.ARGn7VxzHBhS/rustc_testrunner_tmpdir_reporting.hJYasVkFeKoS/mvce.rs:7:5
  |
7 |     _: BadEnum,
  |     ^
  |
  = note: see issue #49804 <https://github.com/rust-lang/rust/issues/49804> for more information
  = help: add `#![feature(unnamed_fields)]` to the crate attributes to enable
  = note: this compiler was built on 2024-02-18; consider upgrading it if it is out of date

error[E0601]: `main` function not found in crate `mvce`
 --> /tmp/icemaker_global_tempdir.ARGn7VxzHBhS/rustc_testrunner_tmpdir_reporting.hJYasVkFeKoS/mvce.rs:8:2
  |
8 | }
  |  ^ consider adding a `main` function to `/tmp/icemaker_global_tempdir.ARGn7VxzHBhS/rustc_testrunner_tmpdir_reporting.hJYasVkFeKoS/mvce.rs`

error: unnamed fields can only have struct or union types
 --> /tmp/icemaker_global_tempdir.ARGn7VxzHBhS/rustc_testrunner_tmpdir_reporting.hJYasVkFeKoS/mvce.rs:5:5
  |
5 |     _: i32,
  |     ^^^^^^

error: unnamed fields can only have struct or union types
 --> /tmp/icemaker_global_tempdir.ARGn7VxzHBhS/rustc_testrunner_tmpdir_reporting.hJYasVkFeKoS/mvce.rs:6:5
  |
6 |     _: MyI32,
  |     ^^^^^^^^

error: unnamed fields can only have struct or union types
 --> /tmp/icemaker_global_tempdir.ARGn7VxzHBhS/rustc_testrunner_tmpdir_reporting.hJYasVkFeKoS/mvce.rs:7:5
  |
7 |     _: BadEnum,
  |     ^^^^^^^^^^

thread 'rustc' panicked at compiler/rustc_hir_analysis/src/collect.rs:797:49:
expect Adt for unnamed field
stack backtrace:
   0:     0x7fee0be69c66 - std::backtrace_rs::backtrace::libunwind::trace::h4068c8c17ac2de87
                               at /rustc/23a3d777c8a95715977608c827de63e7738fa228/library/std/src/../../backtrace/src/backtrace/libunwind.rs:104:5
   1:     0x7fee0be69c66 - std::backtrace_rs::backtrace::trace_unsynchronized::h4580377505c55c9d
                               at /rustc/23a3d777c8a95715977608c827de63e7738fa228/library/std/src/../../backtrace/src/backtrace/mod.rs:66:5
   2:     0x7fee0be69c66 - std::sys_common::backtrace::_print_fmt::hee20b5c666b58216
                               at /rustc/23a3d777c8a95715977608c827de63e7738fa228/library/std/src/sys_common/backtrace.rs:68:5
   3:     0x7fee0be69c66 - <std::sys_common::backtrace::_print::DisplayBacktrace as core::fmt::Display>::fmt::ha4ad425535c00d08
                               at /rustc/23a3d777c8a95715977608c827de63e7738fa228/library/std/src/sys_common/backtrace.rs:44:22
   4:     0x7fee0beba28c - core::fmt::rt::Argument::fmt::h0839985d975a9d4b
                               at /rustc/23a3d777c8a95715977608c827de63e7738fa228/library/core/src/fmt/rt.rs:142:9
   5:     0x7fee0beba28c - core::fmt::write::h90514da5b3f483e8
                               at /rustc/23a3d777c8a95715977608c827de63e7738fa228/library/core/src/fmt/mod.rs:1120:17
   6:     0x7fee0be5d60f - std::io::Write::write_fmt::h203f53b20388cfaa
                               at /rustc/23a3d777c8a95715977608c827de63e7738fa228/library/std/src/io/mod.rs:1846:15
   7:     0x7fee0be69a14 - std::sys_common::backtrace::_print::h2f913a97733fa87b
                               at /rustc/23a3d777c8a95715977608c827de63e7738fa228/library/std/src/sys_common/backtrace.rs:47:5
   8:     0x7fee0be69a14 - std::sys_common::backtrace::print::h99f997f501c28480
                               at /rustc/23a3d777c8a95715977608c827de63e7738fa228/library/std/src/sys_common/backtrace.rs:34:9
   9:     0x7fee0be6c75b - std::panicking::default_hook::{{closure}}::he40fc06be54c384c
  10:     0x7fee0be6c4a9 - std::panicking::default_hook::h3571ea97747a580b
                               at /rustc/23a3d777c8a95715977608c827de63e7738fa228/library/std/src/panicking.rs:292:9
  11:     0x7fee08c1e53c - std[215f9b68e873486f]::panicking::update_hook::<alloc[be5ff64dafe89243]::boxed::Box<rustc_driver_impl[ff846aa700ca0662]::install_ice_hook::{closure#0}>>::{closure#0}
  12:     0x7fee0be6cec0 - <alloc::boxed::Box<F,A> as core::ops::function::Fn<Args>>::call::h1e7c347d2e3bb2ce
                               at /rustc/23a3d777c8a95715977608c827de63e7738fa228/library/alloc/src/boxed.rs:2030:9
  13:     0x7fee0be6cec0 - std::panicking::rust_panic_with_hook::haa768baff731dd68
                               at /rustc/23a3d777c8a95715977608c827de63e7738fa228/library/std/src/panicking.rs:785:13
  14:     0x7fee0be6cc02 - std::panicking::begin_panic_handler::{{closure}}::hd076226a093426e6
                               at /rustc/23a3d777c8a95715977608c827de63e7738fa228/library/std/src/panicking.rs:659:13
  15:     0x7fee0be6a146 - std::sys_common::backtrace::__rust_end_short_backtrace::h5f6128247f895926
                               at /rustc/23a3d777c8a95715977608c827de63e7738fa228/library/std/src/sys_common/backtrace.rs:171:18
  16:     0x7fee0be6c934 - rust_begin_unwind
                               at /rustc/23a3d777c8a95715977608c827de63e7738fa228/library/std/src/panicking.rs:647:5
  17:     0x7fee0beb6795 - core::panicking::panic_fmt::ha3b35be81f6e71fb
                               at /rustc/23a3d777c8a95715977608c827de63e7738fa228/library/core/src/panicking.rs:72:14
  18:     0x7fee0beb6961 - core::panicking::panic_display::h0bc330b58b3ed652
                               at /rustc/23a3d777c8a95715977608c827de63e7738fa228/library/core/src/panicking.rs:196:5
  19:     0x7fee0beb654b - core::panicking::panic_str::hb3484e129df4bb42
                               at /rustc/23a3d777c8a95715977608c827de63e7738fa228/library/core/src/panicking.rs:171:5
  20:     0x7fee0beb654b - core::option::expect_failed::h7f457612ea919a01
                               at /rustc/23a3d777c8a95715977608c827de63e7738fa228/library/core/src/option.rs:1993:5
  21:     0x7fee0a6363f2 - rustc_hir_analysis[6e9724bb0c265329]::collect::find_field
  22:     0x7fee0a63619f - rustc_query_impl[40f1c38ec7f0fe8b]::plumbing::__rust_begin_short_backtrace::<rustc_query_impl[40f1c38ec7f0fe8b]::query_impl::find_field::dynamic_query::{closure#2}::{closure#0}, rustc_middle[1a787087d433af5e]::query::erase::Erased<[u8; 4usize]>>
  23:     0x7fee0a636161 - <rustc_query_impl[40f1c38ec7f0fe8b]::query_impl::find_field::dynamic_query::{closure#2} as core[694f794f8b0567e]::ops::function::FnOnce<(rustc_middle[1a787087d433af5e]::ty::context::TyCtxt, (rustc_span[e2cb3716bc025bf2]::def_id::DefId, rustc_span[e2cb3716bc025bf2]::symbol::Ident))>>::call_once
  24:     0x7fee0a635550 - rustc_query_system[7a228a9eb6f8b90e]::query::plumbing::try_execute_query::<rustc_query_impl[40f1c38ec7f0fe8b]::DynamicConfig<rustc_query_system[7a228a9eb6f8b90e]::query::caches::DefaultCache<(rustc_span[e2cb3716bc025bf2]::def_id::DefId, rustc_span[e2cb3716bc025bf2]::symbol::Ident), rustc_middle[1a787087d433af5e]::query::erase::Erased<[u8; 4usize]>>, false, false, false>, rustc_query_impl[40f1c38ec7f0fe8b]::plumbing::QueryCtxt, false>
  25:     0x7fee0a6352a2 - rustc_query_impl[40f1c38ec7f0fe8b]::query_impl::find_field::get_query_non_incr::__rust_end_short_backtrace
  26:     0x7fee0a1275ae - <rustc_hir_typeck[7e2a8938242ae40f]::fn_ctxt::FnCtxt>::check_field
  27:     0x7fee0a87bbbc - <rustc_hir_typeck[7e2a8938242ae40f]::fn_ctxt::FnCtxt>::check_expr_with_expectation_and_args
  28:     0x7fee0a87b9b0 - <rustc_hir_typeck[7e2a8938242ae40f]::fn_ctxt::FnCtxt>::check_expr_with_expectation_and_args
  29:     0x7fee0a927394 - <rustc_hir_typeck[7e2a8938242ae40f]::fn_ctxt::FnCtxt>::check_argument_types
  30:     0x7fee0a7315af - <rustc_hir_typeck[7e2a8938242ae40f]::fn_ctxt::FnCtxt>::check_call
  31:     0x7fee0a87ad6c - <rustc_hir_typeck[7e2a8938242ae40f]::fn_ctxt::FnCtxt>::check_expr_with_expectation_and_args
  32:     0x7fee0a36d609 - <rustc_hir_typeck[7e2a8938242ae40f]::fn_ctxt::FnCtxt>::check_block_with_expected
  33:     0x7fee0a87b2c2 - <rustc_hir_typeck[7e2a8938242ae40f]::fn_ctxt::FnCtxt>::check_expr_with_expectation_and_args
  34:     0x7fee0a868ac8 - rustc_hir_typeck[7e2a8938242ae40f]::check::check_fn
  35:     0x7fee09f89ef0 - rustc_hir_typeck[7e2a8938242ae40f]::typeck
  36:     0x7fee09f89199 - rustc_query_impl[40f1c38ec7f0fe8b]::plumbing::__rust_begin_short_backtrace::<rustc_query_impl[40f1c38ec7f0fe8b]::query_impl::typeck::dynamic_query::{closure#2}::{closure#0}, rustc_middle[1a787087d433af5e]::query::erase::Erased<[u8; 8usize]>>
  37:     0x7fee09fe81f0 - rustc_query_system[7a228a9eb6f8b90e]::query::plumbing::try_execute_query::<rustc_query_impl[40f1c38ec7f0fe8b]::DynamicConfig<rustc_query_system[7a228a9eb6f8b90e]::query::caches::VecCache<rustc_span[e2cb3716bc025bf2]::def_id::LocalDefId, rustc_middle[1a787087d433af5e]::query::erase::Erased<[u8; 8usize]>>, false, false, false>, rustc_query_impl[40f1c38ec7f0fe8b]::plumbing::QueryCtxt, false>
  38:     0x7fee09fe7dcc - rustc_query_impl[40f1c38ec7f0fe8b]::query_impl::typeck::get_query_non_incr::__rust_end_short_backtrace
  39:     0x7fee09fe7562 - <rustc_middle[1a787087d433af5e]::hir::map::Map>::par_body_owners::<rustc_hir_analysis[6e9724bb0c265329]::check_crate::{closure#5}>::{closure#0}
  40:     0x7fee09fe60a3 - rustc_hir_analysis[6e9724bb0c265329]::check_crate
  41:     0x7fee0a8aadd3 - rustc_interface[ae2941ea76b15824]::passes::analysis
  42:     0x7fee0a8aaa29 - rustc_query_impl[40f1c38ec7f0fe8b]::plumbing::__rust_begin_short_backtrace::<rustc_query_impl[40f1c38ec7f0fe8b]::query_impl::analysis::dynamic_query::{closure#2}::{closure#0}, rustc_middle[1a787087d433af5e]::query::erase::Erased<[u8; 1usize]>>
  43:     0x7fee0ab7b8a5 - rustc_query_system[7a228a9eb6f8b90e]::query::plumbing::try_execute_query::<rustc_query_impl[40f1c38ec7f0fe8b]::DynamicConfig<rustc_query_system[7a228a9eb6f8b90e]::query::caches::SingleCache<rustc_middle[1a787087d433af5e]::query::erase::Erased<[u8; 1usize]>>, false, false, false>, rustc_query_impl[40f1c38ec7f0fe8b]::plumbing::QueryCtxt, false>
  44:     0x7fee0ab7b609 - rustc_query_impl[40f1c38ec7f0fe8b]::query_impl::analysis::get_query_non_incr::__rust_end_short_backtrace
  45:     0x7fee0ab8ec56 - rustc_interface[ae2941ea76b15824]::interface::run_compiler::<core[694f794f8b0567e]::result::Result<(), rustc_span[e2cb3716bc025bf2]::ErrorGuaranteed>, rustc_driver_impl[ff846aa700ca0662]::run_compiler::{closure#0}>::{closure#0}
  46:     0x7fee0adbef06 - std[215f9b68e873486f]::sys_common::backtrace::__rust_begin_short_backtrace::<rustc_interface[ae2941ea76b15824]::util::run_in_thread_with_globals<rustc_interface[ae2941ea76b15824]::util::run_in_thread_pool_with_globals<rustc_interface[ae2941ea76b15824]::interface::run_compiler<core[694f794f8b0567e]::result::Result<(), rustc_span[e2cb3716bc025bf2]::ErrorGuaranteed>, rustc_driver_impl[ff846aa700ca0662]::run_compiler::{closure#0}>::{closure#0}, core[694f794f8b0567e]::result::Result<(), rustc_span[e2cb3716bc025bf2]::ErrorGuaranteed>>::{closure#0}, core[694f794f8b0567e]::result::Result<(), rustc_span[e2cb3716bc025bf2]::ErrorGuaranteed>>::{closure#0}::{closure#0}, core[694f794f8b0567e]::result::Result<(), rustc_span[e2cb3716bc025bf2]::ErrorGuaranteed>>
  47:     0x7fee0adbed32 - <<std[215f9b68e873486f]::thread::Builder>::spawn_unchecked_<rustc_interface[ae2941ea76b15824]::util::run_in_thread_with_globals<rustc_interface[ae2941ea76b15824]::util::run_in_thread_pool_with_globals<rustc_interface[ae2941ea76b15824]::interface::run_compiler<core[694f794f8b0567e]::result::Result<(), rustc_span[e2cb3716bc025bf2]::ErrorGuaranteed>, rustc_driver_impl[ff846aa700ca0662]::run_compiler::{closure#0}>::{closure#0}, core[694f794f8b0567e]::result::Result<(), rustc_span[e2cb3716bc025bf2]::ErrorGuaranteed>>::{closure#0}, core[694f794f8b0567e]::result::Result<(), rustc_span[e2cb3716bc025bf2]::ErrorGuaranteed>>::{closure#0}::{closure#0}, core[694f794f8b0567e]::result::Result<(), rustc_span[e2cb3716bc025bf2]::ErrorGuaranteed>>::{closure#1} as core[694f794f8b0567e]::ops::function::FnOnce<()>>::call_once::{shim:vtable#0}
  48:     0x7fee0be76005 - <alloc::boxed::Box<F,A> as core::ops::function::FnOnce<Args>>::call_once::h8bfba6e4cba56ce0
                               at /rustc/23a3d777c8a95715977608c827de63e7738fa228/library/alloc/src/boxed.rs:2016:9
  49:     0x7fee0be76005 - <alloc::boxed::Box<F,A> as core::ops::function::FnOnce<Args>>::call_once::hf738f5a32d063c18
                               at /rustc/23a3d777c8a95715977608c827de63e7738fa228/library/alloc/src/boxed.rs:2016:9
  50:     0x7fee0be76005 - std::sys::pal::unix::thread::Thread::new::thread_start::h97194e05728842d4
                               at /rustc/23a3d777c8a95715977608c827de63e7738fa228/library/std/src/sys/pal/unix/thread.rs:108:17
  51:     0x7fee05caa9eb - <unknown>
  52:     0x7fee05d2e7cc - <unknown>
  53:                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: rustc 1.78.0-nightly (23a3d777c 2024-02-18) running on x86_64-unknown-linux-gnu

query stack during panic:
#0 [find_field] find the index of maybe nested field `_` in `L`
#1 [typeck] type-checking `<impl at /tmp/icemaker_global_tempdir.ARGn7VxzHBhS/rustc_testrunner_tmpdir_reporting.hJYasVkFeKoS/mvce.rs:3:10: 3:15>::fmt`
#2 [analysis] running analysis passes on this crate
end of query stack
error: aborting due to 9 previous errors

Some errors have detailed explanations: E0412, E0601, E0658.
For more information about an error, try `rustc --explain E0412`.

[matthiaskrgr]

smaller:

#[repr(C)]
#[derive(Debug)]
struct L {
    _: MyI32,
}

[matthiaskrgr]

Seems also to be the 1000th bug found since I started fuzzing 🎉 :)

[clubby789]

@rustbot claim

[clubby789]

While looking into this, it looks like deriveing on a structure with unnamed fields doesn't really work, as it tries to access the field _, resulting in this weird error

error[E0609]: no field `_` on type `&L`
  --> ../poc.rs:13:5
   |
13 |     _: A,
   |     ^ unknown field
   |
help: one of the expressions' fields has a field of the same name
   |
13 |     _: A,
   |

(which crashes with debug assertions due to an empty span).

cc @frank-king