ICE: encountered overly generic constant

[matthiaskrgr]

code from glacier fixed/99575.rs

use std::pin::Pin;

fn main() {
    let a = Enum::A(Pin::new(Box::new(A())));
    let b = Enum::B(Pin::new(Box::new(B())));
    println!("{:?} {:?}", a, b);
}

#[derive(Debug)]
enum Enum {
    A(Pin<Box<A>>),
    B(Pin<Box<B>>),
}

#[derive(Debug)]
struct A();

impl Drop for Pin<Box<A>> {
    fn drop(&mut self) {}
}

#[derive(Debug)]
struct B();

// UNCOMMENT TO FIX COMPILER ERROR
// impl Drop for Pin<Box<B>> {
//     fn drop(&mut self) {}
// }

cargo miri run

Preparing a sysroot for Miri (target: x86_64-unknown-linux-gnu)... done
WARNING: Ignoring `RUSTC_WRAPPER` environment variable, Miri does not support wrapping.
   Compiling M v0.1.0 (/tmp/M)
    Finished dev [unoptimized + debuginfo] target(s) in 0.29s
     Running `/home/matthias/.rustup/toolchains/nightly-x86_64-unknown-linux-gnu/bin/cargo-miri runner target/miri/x86_64-unknown-linux-gnu/debug/M`
warning: crate `M` should have a snake case name
  |
  = note: `#[warn(non_snake_case)]` on by default
  = help: convert the identifier to snake case: `m`

A(A) B(B)
error: internal compiler error: src/tools/miri/src/diagnostics.rs:227:21: This error should be impossible in Miri: encountered overly generic constant

thread 'rustc' panicked at 'Box<dyn Any>', /rustc/0b79f758c9aa6646606662a6d623a0752286cd17/compiler/rustc_errors/src/lib.rs:1393:9
stack backtrace:
   0:     0x7fe9613306d0 - std::backtrace_rs::backtrace::libunwind::trace::hdc27bfa6aa97f84d
                               at /rustc/0b79f758c9aa6646606662a6d623a0752286cd17/library/std/src/../../backtrace/src/backtrace/mod.rs:66:5
   1:     0x7fe9613306d0 - std::backtrace_rs::backtrace::trace_unsynchronized::hd260a87da0307fa5
                               at /rustc/0b79f758c9aa6646606662a6d623a0752286cd17/library/std/src/../../backtrace/src/backtrace/mod.rs:66:5
   2:     0x7fe9613306d0 - std::sys_common::backtrace::_print_fmt::h789cb96c4a337f2c
                               at /rustc/0b79f758c9aa6646606662a6d623a0752286cd17/library/std/src/sys_common/backtrace.rs:66:5
   3:     0x7fe9613306d0 - <std::sys_common::backtrace::_print::DisplayBacktrace as core::fmt::Display>::fmt::h36bc3de3612a60f5
                               at /rustc/0b79f758c9aa6646606662a6d623a0752286cd17/library/std/src/sys_common/backtrace.rs:45:22
   4:     0x7fe96138b76e - core::fmt::write::h2db4bfe92ef037b0
                               at /rustc/0b79f758c9aa6646606662a6d623a0752286cd17/library/core/src/fmt/mod.rs:1202:17
   5:     0x7fe9613214d5 - std::io::Write::write_fmt::hcd345fc714a96537
                               at /rustc/0b79f758c9aa6646606662a6d623a0752286cd17/library/std/src/io/mod.rs:1672:15
   6:     0x7fe961333393 - std::sys_common::backtrace::_print::hcf53c28899e66110
                               at /rustc/0b79f758c9aa6646606662a6d623a0752286cd17/library/std/src/sys_common/backtrace.rs:48:5
   7:     0x7fe961333393 - std::sys_common::backtrace::print::hd8ec3e1ae139ef7a
                               at /rustc/0b79f758c9aa6646606662a6d623a0752286cd17/library/std/src/sys_common/backtrace.rs:35:9
   8:     0x7fe961333393 - std::panicking::default_hook::{{closure}}::he70b99e2f9e5bd44
                               at /rustc/0b79f758c9aa6646606662a6d623a0752286cd17/library/std/src/panicking.rs:295:22
   9:     0x7fe96133307f - std::panicking::default_hook::h8d91a23b91011754
                               at /rustc/0b79f758c9aa6646606662a6d623a0752286cd17/library/std/src/panicking.rs:314:9
  10:     0x7fe963b72644 - <rustc_driver[d9adb13473fd7853]::DEFAULT_HOOK::{closure#0}::{closure#0} as core[97bb3a13db18d0cb]::ops::function::FnOnce<(&core[97bb3a13db18d0cb]::panic::panic_info::PanicInfo,)>>::call_once::{shim:vtable#0}
  11:     0x7fe961333bcd - std::panicking::rust_panic_with_hook::h5af783bc1124b2c1
                               at /rustc/0b79f758c9aa6646606662a6d623a0752286cd17/library/std/src/panicking.rs:702:17
  12:     0x7fe964b103c1 - std[e5af5fec29962f4a]::panicking::begin_panic::<rustc_errors[713e2db940a8ff0d]::ExplicitBug>::{closure#0}
  13:     0x7fe964b0fbc6 - std[e5af5fec29962f4a]::sys_common::backtrace::__rust_end_short_backtrace::<std[e5af5fec29962f4a]::panicking::begin_panic<rustc_errors[713e2db940a8ff0d]::ExplicitBug>::{closure#0}, !>
  14:     0x7fe964af0f46 - std[e5af5fec29962f4a]::panicking::begin_panic::<rustc_errors[713e2db940a8ff0d]::ExplicitBug>
  15:     0x7fe964b359a6 - std[e5af5fec29962f4a]::panic::panic_any::<rustc_errors[713e2db940a8ff0d]::ExplicitBug>
  16:     0x7fe964b34f0d - <rustc_errors[713e2db940a8ff0d]::HandlerInner>::bug::<&alloc[d0a20223ecbdb9c4]::string::String>
  17:     0x7fe964b34c60 - <rustc_errors[713e2db940a8ff0d]::Handler>::bug::<&alloc[d0a20223ecbdb9c4]::string::String>
  18:     0x7fe964b5d23d - rustc_middle[151dce3d5e114089]::ty::context::tls::with_context_opt::<rustc_middle[151dce3d5e114089]::ty::context::tls::with_opt<rustc_middle[151dce3d5e114089]::util::bug::opt_span_bug_fmt<rustc_span[8d4f92e92ba5c24b]::span_encoding::Span>::{closure#0}, ()>::{closure#0}, ()>
  19:     0x7fe964b5f0a6 - rustc_middle[151dce3d5e114089]::util::bug::opt_span_bug_fmt::<rustc_span[8d4f92e92ba5c24b]::span_encoding::Span>
  20:     0x7fe9624fb803 - rustc_middle[151dce3d5e114089]::util::bug::bug_fmt
  21:     0x5573c6aca02e - miri[dae667ef59e4b333]::diagnostics::report_error
  22:     0x5573c6badeb6 - miri[dae667ef59e4b333]::eval::eval_entry
  23:     0x5573c6a34733 - <rustc_interface[67a969eeca26ae2c]::passes::QueryContext>::enter::<<miri[aab31a201f2846f7]::MiriCompilerCalls as rustc_driver[d9adb13473fd7853]::Callbacks>::after_analysis::{closure#0}, ()>
  24:     0x5573c6a3919f - <miri[aab31a201f2846f7]::MiriCompilerCalls as rustc_driver[d9adb13473fd7853]::Callbacks>::after_analysis
  25:     0x7fe9633496eb - <rustc_interface[67a969eeca26ae2c]::interface::Compiler>::enter::<rustc_driver[d9adb13473fd7853]::run_compiler::{closure#1}::{closure#2}, core[97bb3a13db18d0cb]::result::Result<core[97bb3a13db18d0cb]::option::Option<rustc_interface[67a969eeca26ae2c]::queries::Linker>, rustc_errors[713e2db940a8ff0d]::ErrorGuaranteed>>
  26:     0x7fe9633451bc - rustc_span[8d4f92e92ba5c24b]::with_source_map::<core[97bb3a13db18d0cb]::result::Result<(), rustc_errors[713e2db940a8ff0d]::ErrorGuaranteed>, rustc_interface[67a969eeca26ae2c]::interface::create_compiler_and_run<core[97bb3a13db18d0cb]::result::Result<(), rustc_errors[713e2db940a8ff0d]::ErrorGuaranteed>, rustc_driver[d9adb13473fd7853]::run_compiler::{closure#1}>::{closure#1}>
  27:     0x7fe963344ba2 - rustc_interface[67a969eeca26ae2c]::interface::create_compiler_and_run::<core[97bb3a13db18d0cb]::result::Result<(), rustc_errors[713e2db940a8ff0d]::ErrorGuaranteed>, rustc_driver[d9adb13473fd7853]::run_compiler::{closure#1}>
  28:     0x7fe963343741 - <scoped_tls[e4311800d1c0ff57]::ScopedKey<rustc_span[8d4f92e92ba5c24b]::SessionGlobals>>::set::<rustc_interface[67a969eeca26ae2c]::interface::run_compiler<core[97bb3a13db18d0cb]::result::Result<(), rustc_errors[713e2db940a8ff0d]::ErrorGuaranteed>, rustc_driver[d9adb13473fd7853]::run_compiler::{closure#1}>::{closure#0}, core[97bb3a13db18d0cb]::result::Result<(), rustc_errors[713e2db940a8ff0d]::ErrorGuaranteed>>
  29:     0x7fe96334342f - std[e5af5fec29962f4a]::sys_common::backtrace::__rust_begin_short_backtrace::<rustc_interface[67a969eeca26ae2c]::util::run_in_thread_pool_with_globals<rustc_interface[67a969eeca26ae2c]::interface::run_compiler<core[97bb3a13db18d0cb]::result::Result<(), rustc_errors[713e2db940a8ff0d]::ErrorGuaranteed>, rustc_driver[d9adb13473fd7853]::run_compiler::{closure#1}>::{closure#0}, core[97bb3a13db18d0cb]::result::Result<(), rustc_errors[713e2db940a8ff0d]::ErrorGuaranteed>>::{closure#0}, core[97bb3a13db18d0cb]::result::Result<(), rustc_errors[713e2db940a8ff0d]::ErrorGuaranteed>>
  30:     0x7fe963999e79 - <<std[e5af5fec29962f4a]::thread::Builder>::spawn_unchecked_<rustc_interface[67a969eeca26ae2c]::util::run_in_thread_pool_with_globals<rustc_interface[67a969eeca26ae2c]::interface::run_compiler<core[97bb3a13db18d0cb]::result::Result<(), rustc_errors[713e2db940a8ff0d]::ErrorGuaranteed>, rustc_driver[d9adb13473fd7853]::run_compiler::{closure#1}>::{closure#0}, core[97bb3a13db18d0cb]::result::Result<(), rustc_errors[713e2db940a8ff0d]::ErrorGuaranteed>>::{closure#0}, core[97bb3a13db18d0cb]::result::Result<(), rustc_errors[713e2db940a8ff0d]::ErrorGuaranteed>>::{closure#1} as core[97bb3a13db18d0cb]::ops::function::FnOnce<()>>::call_once::{shim:vtable#0}
  31:     0x7fe96133d9c3 - <alloc::boxed::Box<F,A> as core::ops::function::FnOnce<Args>>::call_once::h374ee76b025338a5
                               at /rustc/0b79f758c9aa6646606662a6d623a0752286cd17/library/alloc/src/boxed.rs:1935:9
  32:     0x7fe96133d9c3 - <alloc::boxed::Box<F,A> as core::ops::function::FnOnce<Args>>::call_once::h2bee731a5ba86295
                               at /rustc/0b79f758c9aa6646606662a6d623a0752286cd17/library/alloc/src/boxed.rs:1935:9
  33:     0x7fe96133d9c3 - std::sys::unix::thread::Thread::new::thread_start::h44c172ae3f11ec1f
                               at /rustc/0b79f758c9aa6646606662a6d623a0752286cd17/library/std/src/sys/unix/thread.rs:108:17
  34:     0x7fe960f9c78d - <unknown>
  35:     0x7fe96101d8e4 - clone
  36:                0x0 - <unknown>

note: 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 1.65.0-nightly (0b79f758c 2022-08-18) running on x86_64-unknown-linux-gnu

note: compiler flags: --crate-type bin -C embed-bitcode=no -C debuginfo=2 -C incremental -C target-cpu=native

note: some of the compiler flags provided by cargo are hidden

query stack during panic:
end of query stack
error: aborting due to previous error; 1 warning emitted

[matthiaskrgr]

original rustc ticket: rust-lang/rust#99575

[RalfJung]

I don't think the latest released Miri already contains rust-lang/rust#100740. The version you used certainly did not (it is based on rustc 0b79f758c 2022-08-18).

[RalfJung]

Yeah this got fixed by rust-lang/rust#100740 for Miri as well. When I try it locally with the latest rustc commit I get no ICE, and instead

error[E0120]: the `Drop` trait may only be implemented for local structs, enums, and unions
  --> ice.rs:18:15
   |
18 | impl Drop for Pin<Box<A>> {
   |               ^^^^^^^^^^^ must be a struct, enum, or union in the current crate

error: aborting due to previous error