ICE: unsized_tuple_coercion with debuginfo=2

[matthiaskrgr]

Code

code from ./src/tools/miri/tests/run-pass/unsized-tuple-impls.rs

#![feature(unsized_tuple_coercion)]
fn main() {
    let x : &(i32, i32, [i32]) = &(0, 1, [2, 3]);
}

Meta

rustc --version --verbose:

rustc 1.60.0-nightly (e7aca8959 2022-02-09)
binary: rustc
commit-hash: e7aca895980f25f6d2d3c48e10fd04656764d1e4
commit-date: 2022-02-09
host: x86_64-unknown-linux-gnu
release: 1.60.0-nightly
LLVM version: 13.0.0

Error output

rustc ./src/tools/miri/tests/run-pass/unsized-tuple-impls.rs -Cdebuginfo=2

warning: unused variable: `x`
 --> ./src/tools/miri/tests/run-pass/unsized-tuple-impls.rs:3:9
  |
3 |     let x : &(i32, i32, [i32]) = &(0, 1, [2, 3]);
  |         ^ help: if this is intentional, prefix it with an underscore: `_x`
  |
  = note: `#[warn(unused_variables)]` on by default

thread 'rustc' panicked at 'fat_pointer_kind() - Encountered unexpected `pointee_ty`: (i32, i32, [i32])', compiler/rustc_codegen_llvm/src/debuginfo/utils.rs:102:13

Backtrace

thread 'rustc' panicked at 'fat_pointer_kind() - Encountered unexpected `pointee_ty`: (i32, i32, [i32])', compiler/rustc_codegen_llvm/src/debuginfo/utils.rs:102:13
stack backtrace:
   0:     0x7f4ac58b3b6c - std::backtrace_rs::backtrace::libunwind::trace::h824347123a539ac3
                               at /rustc/e7aca895980f25f6d2d3c48e10fd04656764d1e4/library/std/src/../../backtrace/src/backtrace/libunwind.rs:93:5
   1:     0x7f4ac58b3b6c - std::backtrace_rs::backtrace::trace_unsynchronized::h30996243a6d4a816
                               at /rustc/e7aca895980f25f6d2d3c48e10fd04656764d1e4/library/std/src/../../backtrace/src/backtrace/mod.rs:66:5
   2:     0x7f4ac58b3b6c - std::sys_common::backtrace::_print_fmt::he0e84aa8853fdb2a
                               at /rustc/e7aca895980f25f6d2d3c48e10fd04656764d1e4/library/std/src/sys_common/backtrace.rs:66:5
   3:     0x7f4ac58b3b6c - <std::sys_common::backtrace::_print::DisplayBacktrace as core::fmt::Display>::fmt::h699cf46bd548daad
                               at /rustc/e7aca895980f25f6d2d3c48e10fd04656764d1e4/library/std/src/sys_common/backtrace.rs:45:22
   4:     0x7f4ac591524c - core::fmt::write::hc21dca261faff02f
                               at /rustc/e7aca895980f25f6d2d3c48e10fd04656764d1e4/library/core/src/fmt/mod.rs:1190:17
   5:     0x7f4ac58a3e98 - std::io::Write::write_fmt::ha562dab75b1aee7a
                               at /rustc/e7aca895980f25f6d2d3c48e10fd04656764d1e4/library/std/src/io/mod.rs:1657:15
   6:     0x7f4ac58b7ae7 - std::sys_common::backtrace::_print::h6995311cb4b18c83
                               at /rustc/e7aca895980f25f6d2d3c48e10fd04656764d1e4/library/std/src/sys_common/backtrace.rs:48:5
   7:     0x7f4ac58b7ae7 - std::sys_common::backtrace::print::h5c00a73bc75b17c4
                               at /rustc/e7aca895980f25f6d2d3c48e10fd04656764d1e4/library/std/src/sys_common/backtrace.rs:35:9
   8:     0x7f4ac58b7ae7 - std::panicking::default_hook::{{closure}}::he5c22156c1cfda73
                               at /rustc/e7aca895980f25f6d2d3c48e10fd04656764d1e4/library/std/src/panicking.rs:295:22
   9:     0x7f4ac58b77af - std::panicking::default_hook::hd9340e2830e1e464
                               at /rustc/e7aca895980f25f6d2d3c48e10fd04656764d1e4/library/std/src/panicking.rs:314:9
  10:     0x7f4ac6044d91 - rustc_driver[f7ae5b3e036b262e]::DEFAULT_HOOK::{closure#0}::{closure#0}
  11:     0x7f4ac58b83c5 - std::panicking::rust_panic_with_hook::hb17e9d2f86437995
                               at /rustc/e7aca895980f25f6d2d3c48e10fd04656764d1e4/library/std/src/panicking.rs:702:17
  12:     0x7f4ac58b8077 - std::panicking::begin_panic_handler::{{closure}}::h5ea470c57cd887ae
                               at /rustc/e7aca895980f25f6d2d3c48e10fd04656764d1e4/library/std/src/panicking.rs:588:13
  13:     0x7f4ac58b4014 - std::sys_common::backtrace::__rust_end_short_backtrace::hdf89f68b6e6aa66b
                               at /rustc/e7aca895980f25f6d2d3c48e10fd04656764d1e4/library/std/src/sys_common/backtrace.rs:138:18
  14:     0x7f4ac58b7d79 - rust_begin_unwind
                               at /rustc/e7aca895980f25f6d2d3c48e10fd04656764d1e4/library/std/src/panicking.rs:584:5
  15:     0x7f4ac587fd03 - core::panicking::panic_fmt::h0b506cc131461e16
                               at /rustc/e7aca895980f25f6d2d3c48e10fd04656764d1e4/library/core/src/panicking.rs:143:14
  16:     0x7f4ac72c51fa - rustc_codegen_llvm[de3b2ae653c2b26d]::debuginfo::utils::fat_pointer_kind
  17:     0x7f4ac72a2d3a - rustc_codegen_llvm[de3b2ae653c2b26d]::debuginfo::metadata::pointer_or_reference_metadata
  18:     0x7f4ac72a3aa4 - rustc_codegen_llvm[de3b2ae653c2b26d]::debuginfo::metadata::type_metadata
  19:     0x7f4ac72ec3c5 - rustc_codegen_ssa[f8a21cda5309aefe]::mir::codegen_mir::<rustc_codegen_llvm[de3b2ae653c2b26d]::builder::Builder>
  20:     0x7f4ac72b0212 - rustc_codegen_llvm[de3b2ae653c2b26d]::base::compile_codegen_unit::module_codegen
  21:     0x7f4ac7f43ec6 - <rustc_query_system[fb683e47e947d40]::dep_graph::graph::DepGraph<rustc_middle[69fe71bd9bb50da9]::dep_graph::dep_node::DepKind>>::with_task::<rustc_middle[69fe71bd9bb50da9]::ty::context::TyCtxt, rustc_span[eca3046f9c14e76]::symbol::Symbol, rustc_codegen_ssa[f8a21cda5309aefe]::ModuleCodegen<rustc_codegen_llvm[de3b2ae653c2b26d]::ModuleLlvm>>
  22:     0x7f4ac7f2b51e - rustc_codegen_llvm[de3b2ae653c2b26d]::base::compile_codegen_unit
  23:     0x7f4ac7f4791a - rustc_codegen_ssa[f8a21cda5309aefe]::base::codegen_crate::<rustc_codegen_llvm[de3b2ae653c2b26d]::LlvmCodegenBackend>
  24:     0x7f4ac7f621da - <rustc_codegen_llvm[de3b2ae653c2b26d]::LlvmCodegenBackend as rustc_codegen_ssa[f8a21cda5309aefe]::traits::backend::CodegenBackend>::codegen_crate
  25:     0x7f4ac7eeb9a7 - <rustc_session[e825f980c6f8a293]::session::Session>::time::<alloc[14a0d6d4553afc6a]::boxed::Box<dyn core[b9efde14e06b09ed]::any::Any>, rustc_interface[f21518ebe01ac716]::passes::start_codegen::{closure#0}>
  26:     0x7f4ac7f1597c - <rustc_interface[f21518ebe01ac716]::passes::QueryContext>::enter::<<rustc_interface[f21518ebe01ac716]::queries::Queries>::ongoing_codegen::{closure#0}::{closure#0}, core[b9efde14e06b09ed]::result::Result<alloc[14a0d6d4553afc6a]::boxed::Box<dyn core[b9efde14e06b09ed]::any::Any>, rustc_errors[59c9bb132555b663]::ErrorReported>>
  27:     0x7f4ac7efebef - <rustc_interface[f21518ebe01ac716]::queries::Queries>::ongoing_codegen
  28:     0x7f4ac7ecd831 - rustc_interface[f21518ebe01ac716]::interface::create_compiler_and_run::<core[b9efde14e06b09ed]::result::Result<(), rustc_errors[59c9bb132555b663]::ErrorReported>, rustc_driver[f7ae5b3e036b262e]::run_compiler::{closure#1}>
  29:     0x7f4ac7eb38a2 - std[1e60cef5fcfeb639]::sys_common::backtrace::__rust_begin_short_backtrace::<rustc_interface[f21518ebe01ac716]::util::setup_callbacks_and_run_in_thread_pool_with_globals<rustc_interface[f21518ebe01ac716]::interface::run_compiler<core[b9efde14e06b09ed]::result::Result<(), rustc_errors[59c9bb132555b663]::ErrorReported>, rustc_driver[f7ae5b3e036b262e]::run_compiler::{closure#1}>::{closure#0}, core[b9efde14e06b09ed]::result::Result<(), rustc_errors[59c9bb132555b663]::ErrorReported>>::{closure#0}, core[b9efde14e06b09ed]::result::Result<(), rustc_errors[59c9bb132555b663]::ErrorReported>>
  30:     0x7f4ac7ee4309 - <<std[1e60cef5fcfeb639]::thread::Builder>::spawn_unchecked_<rustc_interface[f21518ebe01ac716]::util::setup_callbacks_and_run_in_thread_pool_with_globals<rustc_interface[f21518ebe01ac716]::interface::run_compiler<core[b9efde14e06b09ed]::result::Result<(), rustc_errors[59c9bb132555b663]::ErrorReported>, rustc_driver[f7ae5b3e036b262e]::run_compiler::{closure#1}>::{closure#0}, core[b9efde14e06b09ed]::result::Result<(), rustc_errors[59c9bb132555b663]::ErrorReported>>::{closure#0}, core[b9efde14e06b09ed]::result::Result<(), rustc_errors[59c9bb132555b663]::ErrorReported>>::{closure#1} as core[b9efde14e06b09ed]::ops::function::FnOnce<()>>::call_once::{shim:vtable#0}
  31:     0x7f4ac58c3e13 - <alloc::boxed::Box<F,A> as core::ops::function::FnOnce<Args>>::call_once::h6b24c31e6604f724
                               at /rustc/e7aca895980f25f6d2d3c48e10fd04656764d1e4/library/alloc/src/boxed.rs:1854:9
  32:     0x7f4ac58c3e13 - <alloc::boxed::Box<F,A> as core::ops::function::FnOnce<Args>>::call_once::h357a4d585864792d
                               at /rustc/e7aca895980f25f6d2d3c48e10fd04656764d1e4/library/alloc/src/boxed.rs:1854:9
  33:     0x7f4ac58c3e13 - std::sys::unix::thread::Thread::new::thread_start::h571ee483c9a2c616
                               at /rustc/e7aca895980f25f6d2d3c48e10fd04656764d1e4/library/std/src/sys/unix/thread.rs:108:17
  34:     0x7f4ac57c9259 - start_thread
  35:     0x7f4ac56e55e3 - __GI___clone
  36:                0x0 - <unknown>

error: internal compiler error: unexpected panic

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 1.60.0-nightly (e7aca8959 2022-02-09) running on x86_64-unknown-linux-gnu

note: compiler flags: -C debuginfo=2

query stack during panic:
end of query stack
warning: 1 warning emitted

[wesleywiser]

cc @michaelwoerister
It looks like this might be related to #93006

[pnkfelix]

cargo-bisect-rustc reports that this is regression in 427eba2 (which is indeed in PR #93006).

[pnkfelix]

@matthiaskrgr reports in zulip that this test case fails at that same injection point when combined with -Cdebuginfo=2 (aka -g):

./src/test/run-pass-valgrind/dst-dtor-4.rs :

Content of above file

#![feature(unsized_tuple_coercion)]

static mut DROP_RAN: isize = 0;

struct Foo;
impl Drop for Foo {
    fn drop(&mut self) {
        unsafe { DROP_RAN += 1; }
    }
}

pub fn main() {
    {
        let _x: Box<(i32, [Foo])> = Box::<(i32, [Foo; 3])>::new((42, [Foo, Foo, Foo]));
    }
    unsafe {
        assert_eq!(DROP_RAN, 3);
    }
}

[matthiaskrgr]

Files that reproduce the ice one way or another with -Cdebuginfo=2 :

./src/tools/miri/tests/run-pass/unsized-tuple-impls.rs
./src/test/run-pass-valgrind/dst-dtor-4.rs
./src/test/ui/dynamically-sized-types/dst-raw.rs
./src/test/ui/dynamically-sized-types/dst-tuple.rs
./src/test/ui/unsized-locals/unsized-exprs-rpass.rs
./src/test/ui/dynamically-sized-types/dst-trait-tuple.rs
./src/test/ui/dynamically-sized-types/dst-tuple-no-reorder.rs
./src/test/ui/dynamically-sized-types/dst-tuple-zst-offsets.rs
./src/test/ui/dynamically-sized-types/dst-tuple-sole.rs
./src/test/ui/dynamically-sized-types/dst-irrefutable-bind.rs
./src/test/ui/unsized/unsized-tuple-impls.rs

[michaelwoerister]

Thanks for the bug report, @matthiaskrgr! I'll look into it.

[michaelwoerister]

Looks like this should be an easy fix. The code just doesn't expect tuples to be unsized (which of course it should).