no errors encountered even though `delay_span_bug` issued

[drewcrawford]

Code

pub trait B {
    type OFuture: Future<Output=O>;
    fn o(&self) -> Self::OFuture;
}
pub trait A {
    type Body: A;
    type BuiltinType:  B;
    fn b(&self) -> Option<&Self::BuiltinType>;
    fn a(&self) -> &Self::Body;
}
use core::future::Future;
pub struct O;

pub fn size<'s,V: A>(view: &'s V) -> impl Future<Output=O> + 's {
    if let Some(builtin) = view.b() {
        builtin.o()
    }
    else {
        size(view.a())
    }
}

Meta

rustc --version --verbose:

rustc 1.62.1 (e092d0b6b 2022-07-16)
binary: rustc
commit-hash: e092d0b6b43f2de967af0887873151bb1c0b18d3
commit-date: 2022-07-16
host: aarch64-apple-darwin
release: 1.62.1
LLVM version: 14.0.5

Error output

error: internal compiler error: no errors encountered even though `delay_span_bug` issued

error: internal compiler error: broken MIR in DefId(0:16 ~ playground[e5a9]::size) (Terminator { source_info: SourceInfo { span: src/lib.rs:19:9: 19:23 (#0), scope: scope[0] }, kind: _0 = size::<<V as A>::Body>(move _7) -> [return: bb7, unwind: bb9] }): call dest mismatch (impl std::future::Future<Output = O> <- impl std::future::Future<Output = O>): NoSolution
  --> src/lib.rs:19:21
   |
19 |         size(view.a())
   |                     ^
   |
   = note: delayed at compiler/rustc_borrowck/src/type_check/mod.rs:1543:21

thread 'rustc' panicked at 'Box<dyn Any>', compiler/rustc_errors/src/lib.rs:1369:13
stack backtrace:
   0:     0x7f2addab5fbd - std::backtrace_rs::backtrace::libunwind::trace::h8e036432725b1c57
                               at /rustc/e092d0b6b43f2de967af0887873151bb1c0b18d3/library/std/src/../../backtrace/src/backtrace/libunwind.rs:93:5
   1:     0x7f2addab5fbd - std::backtrace_rs::backtrace::trace_unsynchronized::h4f83092254c85869
                               at /rustc/e092d0b6b43f2de967af0887873151bb1c0b18d3/library/std/src/../../backtrace/src/backtrace/mod.rs:66:5
   2:     0x7f2addab5fbd - std::sys_common::backtrace::_print_fmt::h9728b5e056a3ece3
                               at /rustc/e092d0b6b43f2de967af0887873151bb1c0b18d3/library/std/src/sys_common/backtrace.rs:66:5
   3:     0x7f2addab5fbd - <std::sys_common::backtrace::_print::DisplayBacktrace as core::fmt::Display>::fmt::h48bb4bd2928827d2
                               at /rustc/e092d0b6b43f2de967af0887873151bb1c0b18d3/library/std/src/sys_common/backtrace.rs:45:22
   4:     0x7f2addb11c4c - core::fmt::write::h909e69a2c24f44cc
                               at /rustc/e092d0b6b43f2de967af0887873151bb1c0b18d3/library/core/src/fmt/mod.rs:1196:17
   5:     0x7f2addaa7731 - std::io::Write::write_fmt::h7f4b8ab8af89e9ef
                               at /rustc/e092d0b6b43f2de967af0887873151bb1c0b18d3/library/std/src/io/mod.rs:1654:15
   6:     0x7f2addab8cd5 - std::sys_common::backtrace::_print::hff4838ebf14a2171
                               at /rustc/e092d0b6b43f2de967af0887873151bb1c0b18d3/library/std/src/sys_common/backtrace.rs:48:5
   7:     0x7f2addab8cd5 - std::sys_common::backtrace::print::h2499280374189ad9
                               at /rustc/e092d0b6b43f2de967af0887873151bb1c0b18d3/library/std/src/sys_common/backtrace.rs:35:9
   8:     0x7f2addab8cd5 - std::panicking::default_hook::{{closure}}::h8b270fc55eeb284e
                               at /rustc/e092d0b6b43f2de967af0887873151bb1c0b18d3/library/std/src/panicking.rs:295:22
   9:     0x7f2addab8949 - std::panicking::default_hook::h3217e229d6e9d13c
                               at /rustc/e092d0b6b43f2de967af0887873151bb1c0b18d3/library/std/src/panicking.rs:314:9
  10:     0x7f2ade27d571 - rustc_driver[b4654d3c4d4292dd]::DEFAULT_HOOK::{closure#0}::{closure#0}
  11:     0x7f2addab94a6 - std::panicking::rust_panic_with_hook::h9acb8048b738d2e0
                               at /rustc/e092d0b6b43f2de967af0887873151bb1c0b18d3/library/std/src/panicking.rs:702:17
  12:     0x7f2adf3ef3e1 - std[8996aeeb2a45fe64]::panicking::begin_panic::<rustc_errors[4633ef6e4608f9c1]::ExplicitBug>::{closure#0}
  13:     0x7f2adf3ef346 - std[8996aeeb2a45fe64]::sys_common::backtrace::__rust_end_short_backtrace::<std[8996aeeb2a45fe64]::panicking::begin_panic<rustc_errors[4633ef6e4608f9c1]::ExplicitBug>::{closure#0}, !>
  14:     0x7f2adf3f2496 - std[8996aeeb2a45fe64]::panicking::begin_panic::<rustc_errors[4633ef6e4608f9c1]::ExplicitBug>
  15:     0x7f2adf3f67f6 - std[8996aeeb2a45fe64]::panic::panic_any::<rustc_errors[4633ef6e4608f9c1]::ExplicitBug>
  16:     0x7f2ae0bb00d1 - <rustc_errors[4633ef6e4608f9c1]::HandlerInner as core[dbea6f494faa966e]::ops::drop::Drop>::drop
  17:     0x7f2ae0310318 - core[dbea6f494faa966e]::ptr::drop_in_place::<rustc_session[a2f3190f51a45935]::parse::ParseSess>
  18:     0x7f2ae0312d53 - <alloc[9c8de9aaaf44fea]::rc::Rc<rustc_session[a2f3190f51a45935]::session::Session> as core[dbea6f494faa966e]::ops::drop::Drop>::drop
  19:     0x7f2ae030fb0d - core[dbea6f494faa966e]::ptr::drop_in_place::<rustc_interface[9f664daa3237129]::interface::Compiler>
  20:     0x7f2ae030f274 - rustc_span[1d0b4d44d1f53955]::with_source_map::<core[dbea6f494faa966e]::result::Result<(), rustc_errors[4633ef6e4608f9c1]::ErrorGuaranteed>, rustc_interface[9f664daa3237129]::interface::create_compiler_and_run<core[dbea6f494faa966e]::result::Result<(), rustc_errors[4633ef6e4608f9c1]::ErrorGuaranteed>, rustc_driver[b4654d3c4d4292dd]::run_compiler::{closure#1}>::{closure#1}>
  21:     0x7f2ae02e7374 - rustc_interface[9f664daa3237129]::interface::create_compiler_and_run::<core[dbea6f494faa966e]::result::Result<(), rustc_errors[4633ef6e4608f9c1]::ErrorGuaranteed>, rustc_driver[b4654d3c4d4292dd]::run_compiler::{closure#1}>
  22:     0x7f2ae02e4c12 - <scoped_tls[ab1554bfb6e7ab15]::ScopedKey<rustc_span[1d0b4d44d1f53955]::SessionGlobals>>::set::<rustc_interface[9f664daa3237129]::interface::run_compiler<core[dbea6f494faa966e]::result::Result<(), rustc_errors[4633ef6e4608f9c1]::ErrorGuaranteed>, rustc_driver[b4654d3c4d4292dd]::run_compiler::{closure#1}>::{closure#0}, core[dbea6f494faa966e]::result::Result<(), rustc_errors[4633ef6e4608f9c1]::ErrorGuaranteed>>
  23:     0x7f2ae02fbdff - std[8996aeeb2a45fe64]::sys_common::backtrace::__rust_begin_short_backtrace::<rustc_interface[9f664daa3237129]::util::run_in_thread_pool_with_globals<rustc_interface[9f664daa3237129]::interface::run_compiler<core[dbea6f494faa966e]::result::Result<(), rustc_errors[4633ef6e4608f9c1]::ErrorGuaranteed>, rustc_driver[b4654d3c4d4292dd]::run_compiler::{closure#1}>::{closure#0}, core[dbea6f494faa966e]::result::Result<(), rustc_errors[4633ef6e4608f9c1]::ErrorGuaranteed>>::{closure#0}, core[dbea6f494faa966e]::result::Result<(), rustc_errors[4633ef6e4608f9c1]::ErrorGuaranteed>>
  24:     0x7f2ae02fbf39 - <<std[8996aeeb2a45fe64]::thread::Builder>::spawn_unchecked_<rustc_interface[9f664daa3237129]::util::run_in_thread_pool_with_globals<rustc_interface[9f664daa3237129]::interface::run_compiler<core[dbea6f494faa966e]::result::Result<(), rustc_errors[4633ef6e4608f9c1]::ErrorGuaranteed>, rustc_driver[b4654d3c4d4292dd]::run_compiler::{closure#1}>::{closure#0}, core[dbea6f494faa966e]::result::Result<(), rustc_errors[4633ef6e4608f9c1]::ErrorGuaranteed>>::{closure#0}, core[dbea6f494faa966e]::result::Result<(), rustc_errors[4633ef6e4608f9c1]::ErrorGuaranteed>>::{closure#1} as core[dbea6f494faa966e]::ops::function::FnOnce<()>>::call_once::{shim:vtable#0}
  25:     0x7f2addac33c3 - <alloc::boxed::Box<F,A> as core::ops::function::FnOnce<Args>>::call_once::h191d5c5ea3edb31d
                               at /rustc/e092d0b6b43f2de967af0887873151bb1c0b18d3/library/alloc/src/boxed.rs:1872:9
  26:     0x7f2addac33c3 - <alloc::boxed::Box<F,A> as core::ops::function::FnOnce<Args>>::call_once::h42ef7cb2ae640a31
                               at /rustc/e092d0b6b43f2de967af0887873151bb1c0b18d3/library/alloc/src/boxed.rs:1872:9
  27:     0x7f2addac33c3 - std::sys::unix::thread::Thread::new::thread_start::he47f7169665dab60
                               at /rustc/e092d0b6b43f2de967af0887873151bb1c0b18d3/library/std/src/sys/unix/thread.rs:108:17
  28:     0x7f2add9f3609 - start_thread
  29:     0x7f2add90c133 - clone
  30:                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 1.62.1 (e092d0b6b 2022-07-16) running on x86_64-unknown-linux-gnu

note: compiler flags: --crate-type lib -C embed-bitcode=no -C codegen-units=1 -C debuginfo=2

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

query stack during panic:
end of query stack
error: could not compile `playground`

Backtrace

<backtrace>

[compiler-errors]

This no longer ICEs after #100092, but instead emits an error:

error: type parameter `V` is part of concrete type but not used in parameter list for the `impl Trait` type alias
  --> FILE:19:9
   |
19 |         size(view.a())
   |         ^^^^^^^^^^^^^^

The "root cause" bug in the provided code is due to the recursive call to size I think.

[compiler-errors]

Closing since this no longer ICEs on nightly.

[astoycos]

Just saw this or something very similar with version: rustc 1.65.0-nightly (cf9ed0dd5 2022-09-15) running on x86_64-unknown-linux-gnu

See https://github.com/redhat-et/bpfd/actions/runs/3069412722/jobs/4958034146#step:11:106

[Jake-Shadle]

We are experiencing the same failure as @astoycos within tower.

[juanky201271]

Me too, since yesterday I can't build my rust library with the nightly version, some idea....?

[compiler-errors]

@Jake-Shadle @juanky201271 Please file separate bugs for this, "Broken MIR" type errors are a wide class and this is probably due to a different root cause.