Box<dyn* Trait> to Box<dyn Trait> ICE

[DutchGhost]

Code

#![feature(dyn_star)]

fn main() {
    let x: dyn* Send = &();
    Box::new(x) as Box<dyn Send>;
}

Meta

rustc --version --verbose:

rustc 1.68.0-nightly (659e169d3 2023-01-04)

Error output

thread 'rustc' panicked at 'assertion failed: `(left == right)`
  left: `DynStar`,
 right: `Dyn`', /rustc/659e169d37990b9c730a59a96081f2ef7afbe8f1/compiler/rustc_codegen_ssa/src/base.rs:156:13

Backtrace

stack backtrace:
   0:     0x7f55bf4af31a - std::backtrace_rs::backtrace::libunwind::trace::h7b93dcf5d2bf5d8f
                               at /rustc/659e169d37990b9c730a59a96081f2ef7afbe8f1/library/std/src/../../backtrace/src/backtrace/libunwind.rs:93:5
   1:     0x7f55bf4af31a - std::backtrace_rs::backtrace::trace_unsynchronized::hca1c5fe7c860d7ad
                               at /rustc/659e169d37990b9c730a59a96081f2ef7afbe8f1/library/std/src/../../backtrace/src/backtrace/mod.rs:66:5
   2:     0x7f55bf4af31a - std::sys_common::backtrace::_print_fmt::h2f271e6d7d34a602
                               at /rustc/659e169d37990b9c730a59a96081f2ef7afbe8f1/library/std/src/sys_common/backtrace.rs:65:5
   3:     0x7f55bf4af31a - <std::sys_common::backtrace::_print::DisplayBacktrace as core::fmt::Display>::fmt::h85ec760477c81cf5
                               at /rustc/659e169d37990b9c730a59a96081f2ef7afbe8f1/library/std/src/sys_common/backtrace.rs:44:22
   4:     0x7f55bf51255e - core::fmt::write::h220487fa128c817c
                               at /rustc/659e169d37990b9c730a59a96081f2ef7afbe8f1/library/core/src/fmt/mod.rs:1208:17
   5:     0x7f55bf49f7f5 - std::io::Write::write_fmt::h34dc3bc331a1c7dd
                               at /rustc/659e169d37990b9c730a59a96081f2ef7afbe8f1/library/std/src/io/mod.rs:1682:15
   6:     0x7f55bf4af0e5 - std::sys_common::backtrace::_print::h3b125ffebe3df857
                               at /rustc/659e169d37990b9c730a59a96081f2ef7afbe8f1/library/std/src/sys_common/backtrace.rs:47:5
   7:     0x7f55bf4af0e5 - std::sys_common::backtrace::print::hf7d8558de48d8cb3
                               at /rustc/659e169d37990b9c730a59a96081f2ef7afbe8f1/library/std/src/sys_common/backtrace.rs:34:9
   8:     0x7f55bf4b1eaf - std::panicking::default_hook::{{closure}}::ha651bf9954ee661b
                               at /rustc/659e169d37990b9c730a59a96081f2ef7afbe8f1/library/std/src/panicking.rs:267:22
   9:     0x7f55bf4b1beb - std::panicking::default_hook::ha6537ec9da38c7b4
                               at /rustc/659e169d37990b9c730a59a96081f2ef7afbe8f1/library/std/src/panicking.rs:286:9
  10:     0x7f55c27c1e74 - <rustc_driver[58f2a498cb46ff05]::DEFAULT_HOOK::{closure#0}::{closure#0} as core[c214e3ae48b876b8]::ops::function::FnOnce<(&core[c214e3ae48b876b8]::panic::panic_info::PanicInfo,)>>::call_once::{shim:vtable#0}
  11:     0x7f55bf4b26ed - <alloc::boxed::Box<F,A> as core::ops::function::Fn<Args>>::call::h88896c197914eaa1
                               at /rustc/659e169d37990b9c730a59a96081f2ef7afbe8f1/library/alloc/src/boxed.rs:2002:9
  12:     0x7f55bf4b26ed - std::panicking::rust_panic_with_hook::he842138d28343c68
                               at /rustc/659e169d37990b9c730a59a96081f2ef7afbe8f1/library/std/src/panicking.rs:692:13
  13:     0x7f55bf4b2469 - std::panicking::begin_panic_handler::{{closure}}::h7a35eb919cedf809
                               at /rustc/659e169d37990b9c730a59a96081f2ef7afbe8f1/library/std/src/panicking.rs:579:13
  14:     0x7f55bf4af7cc - std::sys_common::backtrace::__rust_end_short_backtrace::hb239bdeff35ec750
                               at /rustc/659e169d37990b9c730a59a96081f2ef7afbe8f1/library/std/src/sys_common/backtrace.rs:137:18
  15:     0x7f55bf4b2172 - rust_begin_unwind
                               at /rustc/659e169d37990b9c730a59a96081f2ef7afbe8f1/library/std/src/panicking.rs:575:5
  16:     0x7f55bf50ef23 - core::panicking::panic_fmt::h878a05c5eb5857ea
                               at /rustc/659e169d37990b9c730a59a96081f2ef7afbe8f1/library/core/src/panicking.rs:64:14
  17:     0x7f55bf50f33f - core::panicking::assert_failed_inner::h0329233c302fe17f
  18:     0x7f55c262a232 - core[c214e3ae48b876b8]::panicking::assert_failed::<rustc_type_ir[59ae504fef41e640]::sty::DynKind, rustc_type_ir[59ae504fef41e640]::sty::DynKind>
  19:     0x7f55c0f59bde - rustc_codegen_ssa[a97c59fdb0d9a00c]::base::unsized_info::<rustc_codegen_llvm[eb6b327ede3e8f32]::builder::Builder>
  20:     0x7f55c0f38b31 - rustc_codegen_ssa[a97c59fdb0d9a00c]::base::unsize_ptr::<rustc_codegen_llvm[eb6b327ede3e8f32]::builder::Builder>
  21:     0x7f55c0f38d31 - rustc_codegen_ssa[a97c59fdb0d9a00c]::base::unsize_ptr::<rustc_codegen_llvm[eb6b327ede3e8f32]::builder::Builder>
  22:     0x7f55c0f38d31 - rustc_codegen_ssa[a97c59fdb0d9a00c]::base::unsize_ptr::<rustc_codegen_llvm[eb6b327ede3e8f32]::builder::Builder>
  23:     0x7f55c0f38d31 - rustc_codegen_ssa[a97c59fdb0d9a00c]::base::unsize_ptr::<rustc_codegen_llvm[eb6b327ede3e8f32]::builder::Builder>
  24:     0x7f55c0ef8a20 - <rustc_codegen_ssa[a97c59fdb0d9a00c]::mir::FunctionCx<rustc_codegen_llvm[eb6b327ede3e8f32]::builder::Builder>>::codegen_block
  25:     0x7f55c0ee3777 - rustc_codegen_ssa[a97c59fdb0d9a00c]::mir::codegen_mir::<rustc_codegen_llvm[eb6b327ede3e8f32]::builder::Builder>
  26:     0x7f55c12386a6 - rustc_codegen_llvm[eb6b327ede3e8f32]::base::compile_codegen_unit::module_codegen
  27:     0x7f55c1e95993 - <rustc_query_system[45817d1f18aeef64]::dep_graph::graph::DepGraph<rustc_middle[63a206be65c00384]::dep_graph::dep_node::DepKind>>::with_task::<rustc_middle[63a206be65c00384]::ty::context::TyCtxt, rustc_span[ec779563c92f2e17]::symbol::Symbol, rustc_codegen_ssa[a97c59fdb0d9a00c]::ModuleCodegen<rustc_codegen_llvm[eb6b327ede3e8f32]::ModuleLlvm>>
  28:     0x7f55c1e957c3 - rustc_codegen_llvm[eb6b327ede3e8f32]::base::compile_codegen_unit
  29:     0x7f55c1c67925 - rustc_codegen_ssa[a97c59fdb0d9a00c]::base::codegen_crate::<rustc_codegen_llvm[eb6b327ede3e8f32]::LlvmCodegenBackend>
  30:     0x7f55c1c670f9 - <rustc_codegen_llvm[eb6b327ede3e8f32]::LlvmCodegenBackend as rustc_codegen_ssa[a97c59fdb0d9a00c]::traits::backend::CodegenBackend>::codegen_crate
  31:     0x7f55c1a13f81 - <rustc_session[75adbfaf96023e3]::session::Session>::time::<alloc[97080efe763d84b]::boxed::Box<dyn core[c214e3ae48b876b8]::any::Any>, rustc_interface[3422b3c162eb3570]::passes::start_codegen::{closure#0}>
  32:     0x7f55c1a13aa9 - rustc_interface[3422b3c162eb3570]::passes::start_codegen
  33:     0x7f55c1a117d6 - <rustc_interface[3422b3c162eb3570]::passes::QueryContext>::enter::<<rustc_interface[3422b3c162eb3570]::queries::Queries>::ongoing_codegen::{closure#0}::{closure#0}, core[c214e3ae48b876b8]::result::Result<alloc[97080efe763d84b]::boxed::Box<dyn core[c214e3ae48b876b8]::any::Any>, rustc_errors[6118211e3770648b]::ErrorGuaranteed>>
  34:     0x7f55c1a0ee06 - <rustc_interface[3422b3c162eb3570]::queries::Queries>::ongoing_codegen
  35:     0x7f55c1a0e327 - <rustc_interface[3422b3c162eb3570]::interface::Compiler>::enter::<rustc_driver[58f2a498cb46ff05]::run_compiler::{closure#1}::{closure#2}, core[c214e3ae48b876b8]::result::Result<core[c214e3ae48b876b8]::option::Option<rustc_interface[3422b3c162eb3570]::queries::Linker>, rustc_errors[6118211e3770648b]::ErrorGuaranteed>>
  36:     0x7f55c1a092d8 - rustc_span[ec779563c92f2e17]::with_source_map::<core[c214e3ae48b876b8]::result::Result<(), rustc_errors[6118211e3770648b]::ErrorGuaranteed>, rustc_interface[3422b3c162eb3570]::interface::run_compiler<core[c214e3ae48b876b8]::result::Result<(), rustc_errors[6118211e3770648b]::ErrorGuaranteed>, rustc_driver[58f2a498cb46ff05]::run_compiler::{closure#1}>::{closure#0}::{closure#0}>
  37:     0x7f55c1a08dc5 - <scoped_tls[22f0344cbf7950b5]::ScopedKey<rustc_span[ec779563c92f2e17]::SessionGlobals>>::set::<rustc_interface[3422b3c162eb3570]::interface::run_compiler<core[c214e3ae48b876b8]::result::Result<(), rustc_errors[6118211e3770648b]::ErrorGuaranteed>, rustc_driver[58f2a498cb46ff05]::run_compiler::{closure#1}>::{closure#0}, core[c214e3ae48b876b8]::result::Result<(), rustc_errors[6118211e3770648b]::ErrorGuaranteed>>
  38:     0x7f55c1a083b2 - std[9e86443dd599552f]::sys_common::backtrace::__rust_begin_short_backtrace::<rustc_interface[3422b3c162eb3570]::util::run_in_thread_pool_with_globals<rustc_interface[3422b3c162eb3570]::interface::run_compiler<core[c214e3ae48b876b8]::result::Result<(), rustc_errors[6118211e3770648b]::ErrorGuaranteed>, rustc_driver[58f2a498cb46ff05]::run_compiler::{closure#1}>::{closure#0}, core[c214e3ae48b876b8]::result::Result<(), rustc_errors[6118211e3770648b]::ErrorGuaranteed>>::{closure#0}::{closure#0}, core[c214e3ae48b876b8]::result::Result<(), rustc_errors[6118211e3770648b]::ErrorGuaranteed>>
  39:     0x7f55c2093d8a - <<std[9e86443dd599552f]::thread::Builder>::spawn_unchecked_<rustc_interface[3422b3c162eb3570]::util::run_in_thread_pool_with_globals<rustc_interface[3422b3c162eb3570]::interface::run_compiler<core[c214e3ae48b876b8]::result::Result<(), rustc_errors[6118211e3770648b]::ErrorGuaranteed>, rustc_driver[58f2a498cb46ff05]::run_compiler::{closure#1}>::{closure#0}, core[c214e3ae48b876b8]::result::Result<(), rustc_errors[6118211e3770648b]::ErrorGuaranteed>>::{closure#0}::{closure#0}, core[c214e3ae48b876b8]::result::Result<(), rustc_errors[6118211e3770648b]::ErrorGuaranteed>>::{closure#1} as core[c214e3ae48b876b8]::ops::function::FnOnce<()>>::call_once::{shim:vtable#0}
  40:     0x7f55bf4bcb23 - <alloc::boxed::Box<F,A> as core::ops::function::FnOnce<Args>>::call_once::hec7bbc43877cbd11
                               at /rustc/659e169d37990b9c730a59a96081f2ef7afbe8f1/library/alloc/src/boxed.rs:1988:9
  41:     0x7f55bf4bcb23 - <alloc::boxed::Box<F,A> as core::ops::function::FnOnce<Args>>::call_once::hdfc0a3428bb0d8b0
                               at /rustc/659e169d37990b9c730a59a96081f2ef7afbe8f1/library/alloc/src/boxed.rs:1988:9
  42:     0x7f55bf4bcb23 - std::sys::unix::thread::Thread::new::thread_start::hd2dcc93e4007116d
                               at /rustc/659e169d37990b9c730a59a96081f2ef7afbe8f1/library/std/src/sys/unix/thread.rs:108:17
  43:     0x7f55bf380609 - start_thread
  44:     0x7f55bf2a3133 - clone
  45:                0x0 - <unknown>

[clubby789]

@rustbot label +F-dyn_star

[compiler-errors]

😆 the code thinks that this is a upcast, I think, rather than an unsize coercion. shouldn't be too hard to fix, but I may leave it for someone else.

edit: nvm I'll just fix it.