ICE when running stage 0 library/alloc doctests, stage 1 passes

[the8472]

Running ./x.py test library/alloc/ --stage 0 --doc on commit 25ec827 leads to the the ICE below. The tests pass without error when running the tests under stage 1 instead.

Does that mean some beta backport is missing?

Error output

---- src/string.rs - string::String (line 168) stdout ----
thread 'rustc' panicked at 'called `Option::unwrap()` on a `None` value', compiler/rustc_trait_selection/src/traits/error_reporting/suggestions.rs:696:81
note: run with `RUST_BACKTRACE=1` environment variable to display a backtrace

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 1.56.0-beta.1 (e784c962e 2021-09-07) running on x86_64-unknown-linux-gnu

note: compiler flags: -Z crate-attr=doc(html_root_url="https://doc.rust-lang.org/nightly/") -Z force-unstable-if-unmarked -C codegen-units=1 -C embed-bitcode=no -C target-cpu=native -C link-arg=-fuse-ld=lld -C link-arg=-Wl,--threads=1 -C link-arg=-fuse-ld=lld -C link-arg=-Wl,--threads=1 --crate-type bin

query stack during panic:
#0 [typeck] type-checking `main::_doctest_main_src_string_rs_168_0`
#1 [typeck_item_bodies] type-checking all item bodies
end of query stack
error: internal compiler error: trimmed_def_paths constructed
  |
  = note: delayed at  <snip>

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 1.56.0-beta.1 (e784c962e 2021-09-07) running on x86_64-unknown-linux-gnu

note: compiler flags: -Z crate-attr=doc(html_root_url="https://doc.rust-lang.org/nightly/") -Z force-unstable-if-unmarked -C codegen-units=1 -C embed-bitcode=no -C target-cpu=native -C link-arg=-fuse-ld=lld -C link-arg=-Wl,--threads=1 -C link-arg=-fuse-ld=lld -C link-arg=-Wl,--threads=1 --crate-type bin

query stack during panic:
end of query stack
thread panicked while panicking. aborting.
Some expected error codes were not found: ["E0277"]

failures:
    src/string.rs - string::String (line 168)

test result: FAILED. 598 passed; 1 failed; 1 ignored; 0 measured; 0 filtered out; finished in 2.76s

error: test failed, to rerun pass '--doc'


command did not execute successfully: "/home/the8472/workspace/cargo/target/release/cargo" "test" "--target" "x86_64-unknown-linux-gnu" "-Zbinary-dep-depinfo" "-j" "48" "--release" "--features" "panic-unwind backtrace compiler-builtins-c" "--manifest-path" "/home/the8472/workspace/rust/library/test/Cargo.toml" "-p" "alloc" "--" "--quiet"
expected success, got: exit status: 101

Backtrace

 0: rustc_errors::Handler::delay_good_path_bug
             1: rustc_middle::ty::print::pretty::trimmed_def_paths
             2: rustc_data_structures::stack::ensure_sufficient_stack
             3: rustc_query_system::query::plumbing::get_query_impl
             4: rustc_query_system::query::plumbing::get_query
             5: <rustc_middle::ty::print::pretty::FmtPrinter<F> as rustc_middle::ty::print::Printer>::print_def_path
             6: rustc_middle::ty::print::pretty::PrettyPrinter::pretty_print_type
             7: rustc_middle::ty::print::pretty::<impl rustc_middle::ty::print::Print<P> for rustc_middle::ty::sty::TypeAndMut>::print
             8: rustc_middle::ty::print::pretty::PrettyPrinter::pretty_print_type
             9: rustc_middle::ty::print::pretty::<impl rustc_middle::ty::print::Print<P> for rustc_middle::ty::TraitPredicate>::print
            10: rustc_middle::ty::print::pretty::<impl rustc_middle::ty::print::Print<P> for rustc_middle::ty::PredicateKind>::print
            11: <rustc_middle::ty::print::pretty::FmtPrinter<F> as rustc_middle::ty::print::pretty::PrettyPrinter>::in_binder
            12: rustc_middle::ty::print::pretty::<impl core::fmt::Display for rustc_middle::ty::Predicate>::fmt
            13: core::fmt::write
                       at /rustc/e784c962ea252f0874a4305168077e7048cb39e9/library/core/src/fmt/mod.rs:1150:17
            14: core::fmt::Write::write_fmt
                       at /rustc/e784c962ea252f0874a4305168077e7048cb39e9/library/core/src/fmt/mod.rs:186:9
            15: alloc::fmt::format
                       at /rustc/e784c962ea252f0874a4305168077e7048cb39e9/library/alloc/src/fmt.rs:583:5
            16: <rustc_infer::infer::InferCtxt as rustc_trait_selection::traits::error_reporting::InferCtxtExt>::report_selection_error
            17: <rustc_infer::infer::InferCtxt as rustc_trait_selection::traits::error_reporting::InferCtxtPrivExt>::report_fulfillment_error
            18: <rustc_infer::infer::InferCtxt as rustc_trait_selection::traits::error_reporting::InferCtxtExt>::report_fulfillment_errors
            19: rustc_typeck::check::fn_ctxt::checks::<impl rustc_typeck::check::fn_ctxt::FnCtxt>::check_argument_types
            20: rustc_typeck::check::callee::<impl rustc_typeck::check::fn_ctxt::FnCtxt>::confirm_builtin_call
            21: rustc_typeck::check::callee::<impl rustc_typeck::check::fn_ctxt::FnCtxt>::check_call
            22: rustc_typeck::check::expr::<impl rustc_typeck::check::fn_ctxt::FnCtxt>::check_expr_kind
            23: rustc_typeck::check::expr::<impl rustc_typeck::check::fn_ctxt::FnCtxt>::check_expr_with_expectation
            24: rustc_typeck::check::fn_ctxt::checks::<impl rustc_typeck::check::fn_ctxt::FnCtxt>::check_stmt
            25: rustc_typeck::check::fn_ctxt::checks::<impl rustc_typeck::check::fn_ctxt::FnCtxt>::check_block_with_expected
            26: rustc_typeck::check::expr::<impl rustc_typeck::check::fn_ctxt::FnCtxt>::check_expr_with_expectation
            27: rustc_typeck::check::expr::<impl rustc_typeck::check::fn_ctxt::FnCtxt>::check_return_expr
            28: rustc_typeck::check::check::check_fn
            29: rustc_infer::infer::InferCtxtBuilder::enter
            30: rustc_typeck::check::typeck
            31: rustc_query_system::query::plumbing::get_query_impl
            32: <rustc_query_impl::Queries as rustc_middle::ty::query::QueryEngine>::typeck
            33: rustc_middle::ty::<impl rustc_middle::ty::context::TyCtxt>::par_body_owners
            34: rustc_typeck::check::typeck_item_bodies
            35: rustc_query_system::query::plumbing::get_query_impl
            36: <rustc_query_impl::Queries as rustc_middle::ty::query::QueryEngine>::typeck_item_bodies
            37: rustc_session::utils::<impl rustc_session::session::Session>::time
            38: rustc_typeck::check_crate
            39: rustc_interface::passes::analysis
            40: rustc_query_system::query::plumbing::get_query_impl
            41: <rustc_query_impl::Queries as rustc_middle::ty::query::QueryEngine>::analysis
            42: rustc_interface::passes::QueryContext::enter
            43: rustc_interface::queries::<impl rustc_interface::interface::Compiler>::enter
            44: rustc_span::with_source_map
            45: scoped_tls::ScopedKey<T>::set
            46: std::sys_common::backtrace::__rust_begin_short_backtrace
            47: core::ops::function::FnOnce::call_once{{vtable.shim}}
            48: <alloc::boxed::Box<F,A> as core::ops::function::FnOnce<Args>>::call_once
                       at /rustc/e784c962ea252f0874a4305168077e7048cb39e9/library/alloc/src/boxed.rs:1636:9
            49: <alloc::boxed::Box<F,A> as core::ops::function::FnOnce<Args>>::call_once
                       at /rustc/e784c962ea252f0874a4305168077e7048cb39e9/library/alloc/src/boxed.rs:1636:9
            50: std::sys::unix::thread::Thread::new::thread_start
                       at /rustc/e784c962ea252f0874a4305168077e7048cb39e9/library/std/src/sys/unix/thread.rs:106:17
            51: start_thread
            52: __GI___clone
          

thread 'rustc' panicked at 'no warnings or errors encountered even though `delayed_good_path_bugs` issued', compiler/rustc_errors/src/lib.rs:1166:13
stack backtrace:
   0:     0x7ff60ab994fc - std::backtrace_rs::backtrace::libunwind::trace::h51faa62df48810e4
                               at /rustc/e784c962ea252f0874a4305168077e7048cb39e9/library/std/src/../../backtrace/src/backtrace/libunwind.rs:90:5
   1:     0x7ff60ab994fc - std::backtrace_rs::backtrace::trace_unsynchronized::h91de4d8e16d607e4
                               at /rustc/e784c962ea252f0874a4305168077e7048cb39e9/library/std/src/../../backtrace/src/backtrace/mod.rs:66:5
   2:     0x7ff60ab994fc - std::sys_common::backtrace::_print_fmt::h71b0935f97e4322c
                               at /rustc/e784c962ea252f0874a4305168077e7048cb39e9/library/std/src/sys_common/backtrace.rs:67:5
   3:     0x7ff60ab994fc - <std::sys_common::backtrace::_print::DisplayBacktrace as core::fmt::Display>::fmt::h9a78218788c14e18
                               at /rustc/e784c962ea252f0874a4305168077e7048cb39e9/library/std/src/sys_common/backtrace.rs:46:22
   4:     0x7ff60abf720c - core::fmt::write::h3381b3176fe2b3d3
                               at /rustc/e784c962ea252f0874a4305168077e7048cb39e9/library/core/src/fmt/mod.rs:1150:17
   5:     0x7ff60ab8a435 - std::io::Write::write_fmt::h1d5220480c7a2437
                               at /rustc/e784c962ea252f0874a4305168077e7048cb39e9/library/std/src/io/mod.rs:1667:15
   6:     0x7ff60ab9ca60 - std::sys_common::backtrace::_print::h4b77abc4d907ed0e
                               at /rustc/e784c962ea252f0874a4305168077e7048cb39e9/library/std/src/sys_common/backtrace.rs:49:5
   7:     0x7ff60ab9ca60 - std::sys_common::backtrace::print::hb170c60b542377ad
                               at /rustc/e784c962ea252f0874a4305168077e7048cb39e9/library/std/src/sys_common/backtrace.rs:36:9
   8:     0x7ff60ab9ca60 - std::panicking::default_hook::{{closure}}::h12bbda9af8901ee3
                               at /rustc/e784c962ea252f0874a4305168077e7048cb39e9/library/std/src/panicking.rs:210:50
   9:     0x7ff60ab9c617 - std::panicking::default_hook::h8c6c66d3f3ba6768
                               at /rustc/e784c962ea252f0874a4305168077e7048cb39e9/library/std/src/panicking.rs:227:9
  10:     0x7ff60b370861 - rustc_driver::DEFAULT_HOOK::{{closure}}::{{closure}}::h5d5f6bcd40777e95
  11:     0x7ff60ab9d279 - std::panicking::rust_panic_with_hook::h36f2fa0bb09f4069
                               at /rustc/e784c962ea252f0874a4305168077e7048cb39e9/library/std/src/panicking.rs:628:17
  12:     0x7ff60ab9cd30 - std::panicking::begin_panic_handler::{{closure}}::h9c42b65a42d06a7a
                               at /rustc/e784c962ea252f0874a4305168077e7048cb39e9/library/std/src/panicking.rs:521:13
  13:     0x7ff60ab999c4 - std::sys_common::backtrace::__rust_end_short_backtrace::hc791bddfe31e532c
                               at /rustc/e784c962ea252f0874a4305168077e7048cb39e9/library/std/src/sys_common/backtrace.rs:141:18
  14:     0x7ff60ab9cc99 - rust_begin_unwind
                               at /rustc/e784c962ea252f0874a4305168077e7048cb39e9/library/std/src/panicking.rs:517:5
  15:     0x7ff60ab6181b - std::panicking::begin_panic_fmt::h32ac317c038a272d
                               at /rustc/e784c962ea252f0874a4305168077e7048cb39e9/library/std/src/panicking.rs:460:5
  16:     0x7ff60d8cd54e - rustc_errors::HandlerInner::flush_delayed::hc1a0dc2a3b52b7c5
  17:     0x7ff60d8cbe41 - <rustc_errors::HandlerInner as core::ops::drop::Drop>::drop::h6b6fa9db3b176321
  18:     0x7ff60ce8fb16 - core::ptr::drop_in_place<rustc_session::parse::ParseSess>::h0f64c3a6d9ae48b4
  19:     0x7ff60ce91b0e - <alloc::rc::Rc<T> as core::ops::drop::Drop>::drop::h38ccacfabbb0cd9a
  20:     0x7ff60ce63a8d - core::ptr::drop_in_place<rustc_interface::interface::Compiler>::he462bcfe0a585c06
  21:     0x7ff60ce6376c - rustc_span::with_source_map::h42000c6d4d4801a0
  22:     0x7ff60ce75858 - scoped_tls::ScopedKey<T>::set::h9c4e59a22d2be862
  23:     0x7ff60ce649db - std::sys_common::backtrace::__rust_begin_short_backtrace::hb112af792d752f1d
  24:     0x7ff60ce61b95 - core::ops::function::FnOnce::call_once{{vtable.shim}}::h9bf5ff18e54ee278
  25:     0x7ff60aba98c3 - <alloc::boxed::Box<F,A> as core::ops::function::FnOnce<Args>>::call_once::hbbbb32ef11ea0ad2
                               at /rustc/e784c962ea252f0874a4305168077e7048cb39e9/library/alloc/src/boxed.rs:1636:9
  26:     0x7ff60aba98c3 - <alloc::boxed::Box<F,A> as core::ops::function::FnOnce<Args>>::call_once::h3b8ef23699fc5385
                               at /rustc/e784c962ea252f0874a4305168077e7048cb39e9/library/alloc/src/boxed.rs:1636:9
  27:     0x7ff60aba98c3 - std::sys::unix::thread::Thread::new::thread_start::ha57f5cba35f709b7
                               at /rustc/e784c962ea252f0874a4305168077e7048cb39e9/library/std/src/sys/unix/thread.rs:106:17
  28:     0x7ff60aab3259 - start_thread
  29:     0x7ff60a9c85e3 - __GI___clone
  30:                0x0 - <unknown>

[the8472]

Fixed by #89785