ICE: should be sized but is not? #122581
Description
auto-reduced (treereduce-rust):
pub union BagOfBits<T: Copy> { uninit: (), write: Copy, } pub fn check_bag<T: Copy>(bag: &BagOfBits<T>) { let val = unsafe { (bag as *const _ as *const u8).read() }; } original:
// run-pass #![feature(const_ptr_write)] #![feature(const_mut_refs)] // Or, equivalently: `MaybeUninit`. pub union BagOfBits<T: Copy> { uninit: (), write: Copy, } pub const fn make_1u8_bag<T: Copy>() -> BagOfBits<T> { assert!(core::mem::size_of::<T>() >= 1); let mut bag = BagOfBits { uninit: () }; unsafe { (&mut bag as *mut _ as *mut u8).write(1); }; bag } pub fn check_bag<T: Copy>(bag: &BagOfBits<T>) { let val = unsafe { (bag as *const _ as *const u8).read() }; assert_eq!(val, 1); } fn main() { check_bag(&make_1u8_bag::<[usize; 1]>(1)); // Fine check_bag(&make_1u8_bag::<usize>()); // Fine const CONST_ARRAY_BAG: BagOfBits<[usize; 1]> = make_1u8_bag(); check_bag(&CONST_ARRAY_BAG); // Fine const CONST_USIZE_BAG: BagOfBits<usize> = make_1u8_bag(); // Used to panic since CTFE would make the entire `BagOfBits<usize>` uninit check_bag(&CONST_USIZE_BAG); }Version information
rustc 1.78.0-nightly (c03ea3dfd 2024-03-16) binary: rustc commit-hash: c03ea3dfd907e7dc6305ebf20c94f3a1f1d9fed7 commit-date: 2024-03-16 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[E0601]: `main` function not found in crate `mvce` --> /tmp/icemaker_global_tempdir.rFVXcYalVTX7/rustc_testrunner_tmpdir_reporting.LvGGT1V3WKvx/mvce.rs:8:2 | 8 | } | ^ consider adding a `main` function to `/tmp/icemaker_global_tempdir.rFVXcYalVTX7/rustc_testrunner_tmpdir_reporting.LvGGT1V3WKvx/mvce.rs` warning: trait objects without an explicit `dyn` are deprecated --> /tmp/icemaker_global_tempdir.rFVXcYalVTX7/rustc_testrunner_tmpdir_reporting.LvGGT1V3WKvx/mvce.rs:3:12 | 3 | write: Copy, | ^^^^ | = warning: this is accepted in the current edition (Rust 2015) but is a hard error in Rust 2021! = note: for more information, see <https://doc.rust-lang.org/nightly/edition-guide/rust-2021/warnings-promoted-to-error.html> = note: `#[warn(bare_trait_objects)]` on by default help: if this is an object-safe trait, use `dyn` | 3 | write: dyn Copy, | +++ error[E0038]: the trait `Copy` cannot be made into an object --> /tmp/icemaker_global_tempdir.rFVXcYalVTX7/rustc_testrunner_tmpdir_reporting.LvGGT1V3WKvx/mvce.rs:3:12 | 3 | write: Copy, | ^^^^ `Copy` cannot be made into an object | = note: the trait cannot be made into an object because it requires `Self: Sized` = note: for a trait to be "object safe" it needs to allow building a vtable to allow the call to be resolvable dynamically; for more information visit <https://doc.rust-lang.org/reference/items/traits.html#object-safety> error[E0277]: the size for values of type `(dyn Copy + 'static)` cannot be known at compilation time --> /tmp/icemaker_global_tempdir.rFVXcYalVTX7/rustc_testrunner_tmpdir_reporting.LvGGT1V3WKvx/mvce.rs:3:12 | 3 | write: Copy, | ^^^^ doesn't have a size known at compile-time | = help: the trait `Sized` is not implemented for `(dyn Copy + 'static)` = note: no field of a union may have a dynamically sized type = help: change the field's type to have a statically known size help: borrowed types always have a statically known size | 3 | write: &Copy, | + help: the `Box` type always has a statically known size and allocates its contents in the heap | 3 | write: Box<Copy>, | ++++ + error[E0392]: type parameter `T` is never used --> /tmp/icemaker_global_tempdir.rFVXcYalVTX7/rustc_testrunner_tmpdir_reporting.LvGGT1V3WKvx/mvce.rs:1:21 | 1 | pub union BagOfBits<T: Copy> { | ^ unused type parameter | = help: consider removing `T`, referring to it in a field, or using a marker such as `PhantomData` error[E0740]: field must implement `Copy` or be wrapped in `ManuallyDrop<...>` to be used in a union --> /tmp/icemaker_global_tempdir.rFVXcYalVTX7/rustc_testrunner_tmpdir_reporting.LvGGT1V3WKvx/mvce.rs:3:5 | 3 | write: Copy, | ^^^^^^^^^^^ | = 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<...>` | 3 | write: std::mem::ManuallyDrop<Copy>, | +++++++++++++++++++++++ + error: internal compiler error: `BagOfBits<T/#0>` should be sized but is not? --> /tmp/icemaker_global_tempdir.rFVXcYalVTX7/rustc_testrunner_tmpdir_reporting.LvGGT1V3WKvx/mvce.rs:7:24 | 7 | let val = unsafe { (bag as *const _ as *const u8).read() }; | ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^ thread 'rustc' panicked at compiler/rustc_hir_typeck/src/cast.rs:142:28: Box<dyn Any> stack backtrace: 0: 0x7f9ddfb8c912 - std::backtrace_rs::backtrace::libunwind::trace::h720e7f0c15df28db at /rustc/c03ea3dfd907e7dc6305ebf20c94f3a1f1d9fed7/library/std/src/../../backtrace/src/backtrace/libunwind.rs:105:5 1: 0x7f9ddfb8c912 - std::backtrace_rs::backtrace::trace_unsynchronized::ha9779099a18695a3 at /rustc/c03ea3dfd907e7dc6305ebf20c94f3a1f1d9fed7/library/std/src/../../backtrace/src/backtrace/mod.rs:66:5 2: 0x7f9ddfb8c912 - std::sys_common::backtrace::_print_fmt::h639c233731a9e3cb at /rustc/c03ea3dfd907e7dc6305ebf20c94f3a1f1d9fed7/library/std/src/sys_common/backtrace.rs:68:5 3: 0x7f9ddfb8c912 - <std::sys_common::backtrace::_print::DisplayBacktrace as core::fmt::Display>::fmt::h63ddc66545b2f581 at /rustc/c03ea3dfd907e7dc6305ebf20c94f3a1f1d9fed7/library/std/src/sys_common/backtrace.rs:44:22 4: 0x7f9ddfbddc8c - core::fmt::rt::Argument::fmt::h06c657b2e59a0031 at /rustc/c03ea3dfd907e7dc6305ebf20c94f3a1f1d9fed7/library/core/src/fmt/rt.rs:142:9 5: 0x7f9ddfbddc8c - core::fmt::write::h231dab7207b03bd2 at /rustc/c03ea3dfd907e7dc6305ebf20c94f3a1f1d9fed7/library/core/src/fmt/mod.rs:1153:17 6: 0x7f9ddfb8180f - std::io::Write::write_fmt::h2228d6605854434b at /rustc/c03ea3dfd907e7dc6305ebf20c94f3a1f1d9fed7/library/std/src/io/mod.rs:1843:15 7: 0x7f9ddfb8c6e4 - std::sys_common::backtrace::_print::hac0689b492be0682 at /rustc/c03ea3dfd907e7dc6305ebf20c94f3a1f1d9fed7/library/std/src/sys_common/backtrace.rs:47:5 8: 0x7f9ddfb8c6e4 - std::sys_common::backtrace::print::he630bda5375f1365 at /rustc/c03ea3dfd907e7dc6305ebf20c94f3a1f1d9fed7/library/std/src/sys_common/backtrace.rs:34:9 9: 0x7f9ddfb8f3eb - std::panicking::default_hook::{{closure}}::h9d04fb7bce2d5305 10: 0x7f9ddfb8f143 - std::panicking::default_hook::h142cecc409c8d640 at /rustc/c03ea3dfd907e7dc6305ebf20c94f3a1f1d9fed7/library/std/src/panicking.rs:292:9 11: 0x7f9de2bb4a9e - std[6ebe52f946dd541]::panicking::update_hook::<alloc[54004d19b3858571]::boxed::Box<rustc_driver_impl[f7a8b498200e65bb]::install_ice_hook::{closure#0}>>::{closure#0} 12: 0x7f9ddfb8fb50 - <alloc::boxed::Box<F,A> as core::ops::function::Fn<Args>>::call::h4d1c095d3d6e9872 at /rustc/c03ea3dfd907e7dc6305ebf20c94f3a1f1d9fed7/library/alloc/src/boxed.rs:2034:9 13: 0x7f9ddfb8fb50 - std::panicking::rust_panic_with_hook::h69a135916b9adbd2 at /rustc/c03ea3dfd907e7dc6305ebf20c94f3a1f1d9fed7/library/std/src/panicking.rs:783:13 14: 0x7f9de2be0f34 - std[6ebe52f946dd541]::panicking::begin_panic::<rustc_errors[5de0d917113e7fb6]::ExplicitBug>::{closure#0} 15: 0x7f9de2bddb86 - std[6ebe52f946dd541]::sys_common::backtrace::__rust_end_short_backtrace::<std[6ebe52f946dd541]::panicking::begin_panic<rustc_errors[5de0d917113e7fb6]::ExplicitBug>::{closure#0}, !> 16: 0x7f9de2bd9096 - std[6ebe52f946dd541]::panicking::begin_panic::<rustc_errors[5de0d917113e7fb6]::ExplicitBug> 17: 0x7f9de2bea3b1 - <rustc_errors[5de0d917113e7fb6]::diagnostic::BugAbort as rustc_errors[5de0d917113e7fb6]::diagnostic::EmissionGuarantee>::emit_producing_guarantee 18: 0x7f9de2d0f2c8 - <rustc_errors[5de0d917113e7fb6]::DiagCtxt>::span_bug::<rustc_span[6e2b61d9e5bcc941]::span_encoding::Span, alloc[54004d19b3858571]::string::String> 19: 0x7f9de514996e - <rustc_hir_typeck[6fac15a89779e2b3]::fn_ctxt::FnCtxt>::pointer_kind.cold.0 20: 0x7f9de1a7bebe - <rustc_hir_typeck[6fac15a89779e2b3]::cast::CastCheck>::do_check 21: 0x7f9de48e7845 - <rustc_hir_typeck[6fac15a89779e2b3]::cast::CastCheck>::check 22: 0x7f9de40b0c1e - rustc_hir_typeck[6fac15a89779e2b3]::typeck 23: 0x7f9de40ae05f - rustc_query_impl[d63bb6c0f452187f]::plumbing::__rust_begin_short_backtrace::<rustc_query_impl[d63bb6c0f452187f]::query_impl::typeck::dynamic_query::{closure#2}::{closure#0}, rustc_middle[ea608354392e650]::query::erase::Erased<[u8; 8usize]>> 24: 0x7f9de40ac52e - rustc_query_system[2114d95bfb45a679]::query::plumbing::try_execute_query::<rustc_query_impl[d63bb6c0f452187f]::DynamicConfig<rustc_query_system[2114d95bfb45a679]::query::caches::VecCache<rustc_span[6e2b61d9e5bcc941]::def_id::LocalDefId, rustc_middle[ea608354392e650]::query::erase::Erased<[u8; 8usize]>>, false, false, false>, rustc_query_impl[d63bb6c0f452187f]::plumbing::QueryCtxt, false> 25: 0x7f9de40abf8c - rustc_query_impl[d63bb6c0f452187f]::query_impl::typeck::get_query_non_incr::__rust_end_short_backtrace 26: 0x7f9de43ca5d3 - <rustc_middle[ea608354392e650]::hir::map::Map>::par_body_owners::<rustc_hir_analysis[f2100830a8b528cb]::check_crate::{closure#4}>::{closure#0} 27: 0x7f9de43c926c - rustc_hir_analysis[f2100830a8b528cb]::check_crate 28: 0x7f9de43a452a - rustc_interface[6fcfc136e89dc42e]::passes::analysis 29: 0x7f9de43a4165 - rustc_query_impl[d63bb6c0f452187f]::plumbing::__rust_begin_short_backtrace::<rustc_query_impl[d63bb6c0f452187f]::query_impl::analysis::dynamic_query::{closure#2}::{closure#0}, rustc_middle[ea608354392e650]::query::erase::Erased<[u8; 1usize]>> 30: 0x7f9de4c088a5 - rustc_query_system[2114d95bfb45a679]::query::plumbing::try_execute_query::<rustc_query_impl[d63bb6c0f452187f]::DynamicConfig<rustc_query_system[2114d95bfb45a679]::query::caches::SingleCache<rustc_middle[ea608354392e650]::query::erase::Erased<[u8; 1usize]>>, false, false, false>, rustc_query_impl[d63bb6c0f452187f]::plumbing::QueryCtxt, false> 31: 0x7f9de4c08609 - rustc_query_impl[d63bb6c0f452187f]::query_impl::analysis::get_query_non_incr::__rust_end_short_backtrace 32: 0x7f9de4963284 - rustc_interface[6fcfc136e89dc42e]::interface::run_compiler::<core[7931fcdfa73bbef6]::result::Result<(), rustc_span[6e2b61d9e5bcc941]::ErrorGuaranteed>, rustc_driver_impl[f7a8b498200e65bb]::run_compiler::{closure#0}>::{closure#0} 33: 0x7f9de4e54385 - std[6ebe52f946dd541]::sys_common::backtrace::__rust_begin_short_backtrace::<rustc_interface[6fcfc136e89dc42e]::util::run_in_thread_with_globals<rustc_interface[6fcfc136e89dc42e]::util::run_in_thread_pool_with_globals<rustc_interface[6fcfc136e89dc42e]::interface::run_compiler<core[7931fcdfa73bbef6]::result::Result<(), rustc_span[6e2b61d9e5bcc941]::ErrorGuaranteed>, rustc_driver_impl[f7a8b498200e65bb]::run_compiler::{closure#0}>::{closure#0}, core[7931fcdfa73bbef6]::result::Result<(), rustc_span[6e2b61d9e5bcc941]::ErrorGuaranteed>>::{closure#0}, core[7931fcdfa73bbef6]::result::Result<(), rustc_span[6e2b61d9e5bcc941]::ErrorGuaranteed>>::{closure#0}::{closure#0}, core[7931fcdfa73bbef6]::result::Result<(), rustc_span[6e2b61d9e5bcc941]::ErrorGuaranteed>> 34: 0x7f9de4e541b2 - <<std[6ebe52f946dd541]::thread::Builder>::spawn_unchecked_<rustc_interface[6fcfc136e89dc42e]::util::run_in_thread_with_globals<rustc_interface[6fcfc136e89dc42e]::util::run_in_thread_pool_with_globals<rustc_interface[6fcfc136e89dc42e]::interface::run_compiler<core[7931fcdfa73bbef6]::result::Result<(), rustc_span[6e2b61d9e5bcc941]::ErrorGuaranteed>, rustc_driver_impl[f7a8b498200e65bb]::run_compiler::{closure#0}>::{closure#0}, core[7931fcdfa73bbef6]::result::Result<(), rustc_span[6e2b61d9e5bcc941]::ErrorGuaranteed>>::{closure#0}, core[7931fcdfa73bbef6]::result::Result<(), rustc_span[6e2b61d9e5bcc941]::ErrorGuaranteed>>::{closure#0}::{closure#0}, core[7931fcdfa73bbef6]::result::Result<(), rustc_span[6e2b61d9e5bcc941]::ErrorGuaranteed>>::{closure#1} as core[7931fcdfa73bbef6]::ops::function::FnOnce<()>>::call_once::{shim:vtable#0} 35: 0x7f9ddfb991e5 - <alloc::boxed::Box<F,A> as core::ops::function::FnOnce<Args>>::call_once::h2cd6598022142910 at /rustc/c03ea3dfd907e7dc6305ebf20c94f3a1f1d9fed7/library/alloc/src/boxed.rs:2020:9 36: 0x7f9ddfb991e5 - <alloc::boxed::Box<F,A> as core::ops::function::FnOnce<Args>>::call_once::hfc8920891f2f584d at /rustc/c03ea3dfd907e7dc6305ebf20c94f3a1f1d9fed7/library/alloc/src/boxed.rs:2020:9 37: 0x7f9ddfb991e5 - std::sys::pal::unix::thread::Thread::new::thread_start::h31aea03b1d783db7 at /rustc/c03ea3dfd907e7dc6305ebf20c94f3a1f1d9fed7/library/std/src/sys/pal/unix/thread.rs:108:17 38: 0x7f9ddf98155a - <unknown> 39: 0x7f9ddf9fea3c - <unknown> 40: 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: rustc 1.78.0-nightly (c03ea3dfd 2024-03-16) running on x86_64-unknown-linux-gnu query stack during panic: #0 [typeck] type-checking `check_bag` #1 [analysis] running analysis passes on this crate end of query stack error: aborting due to 6 previous errors; 1 warning emitted Some errors have detailed explanations: E0038, E0277, E0392, E0601, E0740. For more information about an error, try `rustc --explain E0038`.