ICE: rustdoc on overlap-not-permitted-for-builtin-trait.rs: unable to fulfill trait

[matthiaskrgr]

Code

code from ./src/test/ui/traits/overlap-not-permitted-for-builtin-trait.rs

#![allow(dead_code)]
#![feature(negative_impls)]

// Overlapping negative impls for `MyStruct` are not permitted:
struct MyStruct;
impl !Send for MyStruct {}
impl !Send for MyStruct {}
//~^ ERROR conflicting implementations of trait

fn main() {}

Meta

rustc --version --verbose:

rustdoc 1.50.0-nightly (1c389ffef 2020-11-24)
binary: rustdoc
commit-hash: 1c389ffeff814726dec325f0f2b0c99107df2673
commit-date: 2020-11-24
host: x86_64-unknown-linux-gnu
release: 1.50.0-nightly

Error output

thread 'rustc' panicked at 'Unable to fulfill trait DefId(2:2049 ~ core[27a9]::marker::Send) for 'MyStruct': [FulfillmentError(Obligation(predicate=TraitPredicate(<MyStruct as std::marker::Send>), depth=0),Ambiguity)]', /rustc/1c389ffeff814726dec325f0f2b0c99107df2673/compiler/rustc_trait_selection/src/traits/auto_trait.rs:193:17
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 1.50.0-nightly (1c389ffef 2020-11-24) running on x86_64-unknown-linux-gnu

query stack during panic:
end of query stack

Backtrace

hread 'rustc' panicked at 'Unable to fulfill trait DefId(2:2049 ~ core[27a9]::marker::Send) for 'MyStruct': [FulfillmentError(Obligation(predicate=TraitPredicate(<MyStruct as std::marker::Send>), depth=0),Ambiguity)]', /rustc/1c389ffeff814726dec325f0f2b0c99107df2673/compiler/rustc_trait_selection/src/traits/auto_trait.rs:193:17
stack backtrace:
   0:     0x7ff9fb0ffe30 - std::backtrace_rs::backtrace::libunwind::trace::h746c3e9529d524bc
                               at /rustc/1c389ffeff814726dec325f0f2b0c99107df2673/library/std/src/../../backtrace/src/backtrace/libunwind.rs:90:5
   1:     0x7ff9fb0ffe30 - std::backtrace_rs::backtrace::trace_unsynchronized::h86340908ff889faa
                               at /rustc/1c389ffeff814726dec325f0f2b0c99107df2673/library/std/src/../../backtrace/src/backtrace/mod.rs:66:5
   2:     0x7ff9fb0ffe30 - std::sys_common::backtrace::_print_fmt::h43f85f9b18230404
                               at /rustc/1c389ffeff814726dec325f0f2b0c99107df2673/library/std/src/sys_common/backtrace.rs:67:5
   3:     0x7ff9fb0ffe30 - <std::sys_common::backtrace::_print::DisplayBacktrace as core::fmt::Display>::fmt::hc132ae1a5b5aa7cd
                               at /rustc/1c389ffeff814726dec325f0f2b0c99107df2673/library/std/src/sys_common/backtrace.rs:46:22
   4:     0x7ff9fb172c4c - core::fmt::write::hdf023a0036d2a25f
                               at /rustc/1c389ffeff814726dec325f0f2b0c99107df2673/library/core/src/fmt/mod.rs:1078:17
   5:     0x7ff9fb0f19a2 - std::io::Write::write_fmt::h8580846154bcb66a
                               at /rustc/1c389ffeff814726dec325f0f2b0c99107df2673/library/std/src/io/mod.rs:1519:15
   6:     0x7ff9fb103a95 - std::sys_common::backtrace::_print::h7ee55fed88d107a3
                               at /rustc/1c389ffeff814726dec325f0f2b0c99107df2673/library/std/src/sys_common/backtrace.rs:49:5
   7:     0x7ff9fb103a95 - std::sys_common::backtrace::print::h54a7d3e52a524177
                               at /rustc/1c389ffeff814726dec325f0f2b0c99107df2673/library/std/src/sys_common/backtrace.rs:36:9
   8:     0x7ff9fb103a95 - std::panicking::default_hook::{{closure}}::h60921e857bf55a40
                               at /rustc/1c389ffeff814726dec325f0f2b0c99107df2673/library/std/src/panicking.rs:208:50
   9:     0x7ff9fb1035ea - std::panicking::default_hook::hf0f9afb1017317fc
                               at /rustc/1c389ffeff814726dec325f0f2b0c99107df2673/library/std/src/panicking.rs:225:9
  10:     0x7ff9fb990bb8 - rustc_driver::report_ice::ha25ae86a5858acc3
  11:     0x7ff9fb104396 - std::panicking::rust_panic_with_hook::h8d66bf42b407aaea
                               at /rustc/1c389ffeff814726dec325f0f2b0c99107df2673/library/std/src/panicking.rs:595:17
  12:     0x7ff9fb103eb7 - std::panicking::begin_panic_handler::{{closure}}::hde71edcd925d0c5e
                               at /rustc/1c389ffeff814726dec325f0f2b0c99107df2673/library/std/src/panicking.rs:497:13
  13:     0x7ff9fb1002ec - std::sys_common::backtrace::__rust_end_short_backtrace::h8a3c7d6cea578919
                               at /rustc/1c389ffeff814726dec325f0f2b0c99107df2673/library/std/src/sys_common/backtrace.rs:141:18
  14:     0x7ff9fb103e19 - rust_begin_unwind
                               at /rustc/1c389ffeff814726dec325f0f2b0c99107df2673/library/std/src/panicking.rs:493:5
  15:     0x7ff9fb103dcb - std::panicking::begin_panic_fmt::hee67ce14b77d0396
                               at /rustc/1c389ffeff814726dec325f0f2b0c99107df2673/library/std/src/panicking.rs:435:5
  16:     0x559298e2b2f0 - rustc_trait_selection::traits::auto_trait::AutoTraitFinder::find_auto_trait_generics::{{closure}}::{{closure}}::h2cca4e6ec6acf209
  17:     0x559298e1d561 - rustc_infer::infer::InferCtxtBuilder::enter::hd535b0600c13c07b
  18:     0x559298d3a6f8 - rustc_trait_selection::traits::auto_trait::AutoTraitFinder::find_auto_trait_generics::h3e6f0b992fc91d80
  19:     0x559298e2e821 - core::ops::function::impls::<impl core::ops::function::FnMut<A> for &mut F>::call_mut::h9ebd0359a0d784f8
  20:     0x559298fb4269 - <alloc::vec::Vec<T> as alloc::vec::SpecFromIter<T,I>>::from_iter::h41802ce24eaf1fb0
  21:     0x559298f417f8 - rustdoc::clean::utils::get_auto_trait_and_blanket_impls::h38708bc1e4d8b0b8
  22:     0x559298cc94d7 - <rustdoc::passes::collect_trait_impls::SyntheticImplCollector as rustdoc::fold::DocFolder>::fold_item::h217a0b74ff87ad2f
  23:     0x559298fb192a - <alloc::vec::Vec<T> as alloc::vec::SpecFromIter<T,I>>::from_iter::h7133d90fc589f51b
  24:     0x559298cbab5c - rustdoc::fold::DocFolder::fold_inner_recur::h7f389b925cd18d4e
  25:     0x559298cc9383 - <rustdoc::passes::collect_trait_impls::SyntheticImplCollector as rustdoc::fold::DocFolder>::fold_item::h217a0b74ff87ad2f
  26:     0x559298cc67d4 - rustdoc::passes::collect_trait_impls::collect_trait_impls::h4af45e32e779fa37
  27:     0x559298cb8acf - rustdoc::core::run_global_ctxt::h7cf39be6ea65128e
  28:     0x559298d31ece - rustc_interface::passes::QueryContext::enter::hedb615e17429b641
  29:     0x559298e27917 - rustc_interface::interface::create_compiler_and_run::h25fa5935e40978f2
  30:     0x559298cce0d3 - rustdoc::main_options::h8a5cda9c1c8c625b
  31:     0x559298e18a68 - rustc_span::with_session_globals::h7a83fbbd64fb6823
  32:     0x559298cff30e - std::sys_common::backtrace::__rust_begin_short_backtrace::h50722f4a01515f7b
  33:     0x559298e3103a - core::ops::function::FnOnce::call_once{{vtable.shim}}::h22276985fb540191
  34:     0x7ff9fb11365a - <alloc::boxed::Box<F,A> as core::ops::function::FnOnce<Args>>::call_once::hea1090dbdcecbf5a
                               at /rustc/1c389ffeff814726dec325f0f2b0c99107df2673/library/alloc/src/boxed.rs:1318:9
  35:     0x7ff9fb11365a - <alloc::boxed::Box<F,A> as core::ops::function::FnOnce<Args>>::call_once::h8d5723d3912bd325
                               at /rustc/1c389ffeff814726dec325f0f2b0c99107df2673/library/alloc/src/boxed.rs:1318:9
  36:     0x7ff9fb11365a - std::sys::unix::thread::Thread::new::thread_start::hc17a425ca2995724
                               at /rustc/1c389ffeff814726dec325f0f2b0c99107df2673/library/std/src/sys/unix/thread.rs:71:17
  37:     0x7ff9fafef3e9 - start_thread
  38:     0x7ff9fadd5293 - __GI___clone
  39:                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 1.50.0-nightly (1c389ffef 2020-11-24) running on x86_64-unknown-linux-gnu

query stack during panic:
end of query stack

[jyn514]

I expect this is the same sort of issue as #73566 (comment) where rustdoc doesn't run typeck passes that other parts of the compiler assume have been run.

Assigning P-low by the same rationale as #79496 (comment).

[Alexendoo]

No longer ICEs since #95333