ICE "unresolved inference variable in outlives"

[SimonSapin]

Documenting Servo with rustc 1.32.0-nightly (f4a421e 2018-12-13) gives the error below. Compiling the same crate works.

error: internal compiler error: unresolved inference variable in outlives: _#1t

error: internal compiler error: unresolved inference variable in outlives: _#6t

thread '<unnamed>' panicked at 'no errors encountered even though `delay_span_bug` issued', src/librustc_errors/lib.rs:334:17
stack backtrace:
   0: std::sys::unix::backtrace::tracing::imp::unwind_backtrace
             at src/libstd/sys/unix/backtrace/tracing/gcc_s.rs:49
   1: std::sys_common::backtrace::_print
             at src/libstd/sys_common/backtrace.rs:71
   2: std::panicking::default_hook::{{closure}}
             at src/libstd/sys_common/backtrace.rs:59
             at src/libstd/panicking.rs:210
   3: std::panicking::default_hook
             at src/libstd/panicking.rs:224
   4: std::panicking::rust_panic_with_hook
             at src/libstd/panicking.rs:491
   5: std::panicking::begin_panic
   6: <rustc_errors::Handler as core::ops::drop::Drop>::drop
   7: core::ptr::real_drop_in_place
             at /rustc/f4a421ee3cf1259f0750ac7fabd19da1d8551e4c/src/libcore/ptr.rs:204
   8: core::ptr::real_drop_in_place
             at /rustc/f4a421ee3cf1259f0750ac7fabd19da1d8551e4c/src/libcore/ptr.rs:204
   9: core::ptr::real_drop_in_place
             at /rustc/f4a421ee3cf1259f0750ac7fabd19da1d8551e4c/src/libcore/ptr.rs:204
  10: <scoped_tls::ScopedKey<T>>::set
             at src/librustdoc/core.rs:623
             at /rustc/f4a421ee3cf1259f0750ac7fabd19da1d8551e4c/src/librustc_driver/driver.rs:76
             at /cargo/registry/src/github.com-1ecc6299db9ec823/scoped-tls-0.1.2/src/lib.rs:155
  11: rustdoc::core::run_core
             at /rustc/f4a421ee3cf1259f0750ac7fabd19da1d8551e4c/src/librustc_driver/driver.rs:75
             at src/librustdoc/core.rs:404
  12: <scoped_tls::ScopedKey<T>>::set
             at src/librustdoc/lib.rs:425
             at /cargo/registry/src/github.com-1ecc6299db9ec823/scoped-tls-0.1.2/src/lib.rs:155
             at /rustc/f4a421ee3cf1259f0750ac7fabd19da1d8551e4c/src/libsyntax/lib.rs:123
             at /cargo/registry/src/github.com-1ecc6299db9ec823/scoped-tls-0.1.2/src/lib.rs:155
  13: syntax::with_globals
             at /rustc/f4a421ee3cf1259f0750ac7fabd19da1d8551e4c/src/libsyntax/lib.rs:122
  14: std::panicking::try::do_call
             at src/librustdoc/lib.rs:422
             at /rustc/f4a421ee3cf1259f0750ac7fabd19da1d8551e4c/src/librustc_driver/lib.rs:1642
             at /rustc/f4a421ee3cf1259f0750ac7fabd19da1d8551e4c/src/libstd/panic.rs:319
             at /rustc/f4a421ee3cf1259f0750ac7fabd19da1d8551e4c/src/libstd/panicking.rs:306
  15: __rust_maybe_catch_panic
             at src/libpanic_unwind/lib.rs:102
  16: rustc_driver::monitor
             at /rustc/f4a421ee3cf1259f0750ac7fabd19da1d8551e4c/src/libstd/panicking.rs:285
             at /rustc/f4a421ee3cf1259f0750ac7fabd19da1d8551e4c/src/libstd/panic.rs:398
             at /rustc/f4a421ee3cf1259f0750ac7fabd19da1d8551e4c/src/librustc_driver/lib.rs:1556
             at /rustc/f4a421ee3cf1259f0750ac7fabd19da1d8551e4c/src/librustc_driver/lib.rs:1567
             at /rustc/f4a421ee3cf1259f0750ac7fabd19da1d8551e4c/src/librustc_driver/lib.rs:1641
  17: rustdoc::main_args
             at src/librustdoc/lib.rs:422
             at src/librustdoc/lib.rs:385
  18: <scoped_tls::ScopedKey<T>>::set
             at src/librustdoc/lib.rs:108
             at /rustc/f4a421ee3cf1259f0750ac7fabd19da1d8551e4c/src/libcore/option.rs:424
             at src/librustdoc/lib.rs:108
             at /cargo/registry/src/github.com-1ecc6299db9ec823/scoped-tls-0.1.2/src/lib.rs:155
             at /rustc/f4a421ee3cf1259f0750ac7fabd19da1d8551e4c/src/libsyntax/lib.rs:123
             at /cargo/registry/src/github.com-1ecc6299db9ec823/scoped-tls-0.1.2/src/lib.rs:155
  19: syntax::with_globals
             at /rustc/f4a421ee3cf1259f0750ac7fabd19da1d8551e4c/src/libsyntax/lib.rs:122
  20: std::panicking::try::do_call
             at /rustc/f4a421ee3cf1259f0750ac7fabd19da1d8551e4c/src/libstd/thread/mod.rs:479
             at /rustc/f4a421ee3cf1259f0750ac7fabd19da1d8551e4c/src/libstd/panic.rs:319
             at /rustc/f4a421ee3cf1259f0750ac7fabd19da1d8551e4c/src/libstd/panicking.rs:306
  21: __rust_maybe_catch_panic
             at src/libpanic_unwind/lib.rs:102
  22: <F as alloc::boxed::FnBox<A>>::call_box
             at /rustc/f4a421ee3cf1259f0750ac7fabd19da1d8551e4c/src/libstd/panicking.rs:285
             at /rustc/f4a421ee3cf1259f0750ac7fabd19da1d8551e4c/src/libstd/panic.rs:398
             at /rustc/f4a421ee3cf1259f0750ac7fabd19da1d8551e4c/src/libstd/thread/mod.rs:478
             at /rustc/f4a421ee3cf1259f0750ac7fabd19da1d8551e4c/src/liballoc/boxed.rs:673
  23: std::sys::unix::thread::Thread::new::thread_start
             at /rustc/f4a421ee3cf1259f0750ac7fabd19da1d8551e4c/src/liballoc/boxed.rs:683
             at src/libstd/sys_common/thread.rs:24
             at src/libstd/sys/unix/thread.rs:91
  24: start_thread
  25: __clone

error: internal compiler error: unexpected panic

error: Unrecognized option: 'document-private-items'

error: Could not document `style`.

https://tools.taskcluster.net/groups/WPxk_v22QWeMYOGGDJbBIA/tasks/HSLf3bjIR8u7qj3mkKtYaQ/runs/0/logs/public%2Flogs%2Flive.log

[QuietMisdreavus]

I'm going to hazard a guess that the "unrecognized option" message is unrelated to the actual error. We get messages in travis about markdown-css as well.

The fact that this is an uncaught error makes it harder to see where it came from, though... Is it possible to run this with RUSTDOCFLAGS="-Z treat-err-as-bug" so we can catch it as it happens?

[SimonSapin]

Sure.

error: internal compiler error: unresolved inference variable in outlives: _#1t

thread '<unnamed>' panicked at 'encountered error with `-Z treat_err_as_bug', src/librustc_errors/lib.rs:500:13
stack backtrace:
   0: std::sys::unix::backtrace::tracing::imp::unwind_backtrace
             at src/libstd/sys/unix/backtrace/tracing/gcc_s.rs:49
   1: std::sys_common::backtrace::_print
             at src/libstd/sys_common/backtrace.rs:71
   2: std::panicking::default_hook::{{closure}}
             at src/libstd/sys_common/backtrace.rs:59
             at src/libstd/panicking.rs:210
   3: std::panicking::default_hook
             at src/libstd/panicking.rs:224
   4: std::panicking::rust_panic_with_hook
             at src/libstd/panicking.rs:491
   5: std::panicking::begin_panic
   6: rustc_errors::Handler::emit_db
   7: rustc_errors::Handler::emit
   8: rustc_errors::Handler::span_bug
   9: rustc_errors::Handler::delay_span_bug
  10: <rustc::infer::outlives::obligations::TypeOutlives<'cx, 'gcx, 'tcx, D>>::components_must_outlive
  11: <rustc::infer::outlives::obligations::TypeOutlives<'cx, 'gcx, 'tcx, D>>::type_must_outlive
  12: rustc::infer::outlives::obligations::<impl rustc::infer::InferCtxt<'cx, 'gcx, 'tcx>>::process_registered_region_obligations
  13: rustc::ty::context::tls::with_context::{{closure}}
             at /rustc/f4a421ee3cf1259f0750ac7fabd19da1d8551e4c/src/librustc/traits/auto_trait.rs:240
             at /rustc/f4a421ee3cf1259f0750ac7fabd19da1d8551e4c/src/librustc/infer/mod.rs:526
             at /rustc/f4a421ee3cf1259f0750ac7fabd19da1d8551e4c/src/librustc/ty/context.rs:1635
             at /rustc/f4a421ee3cf1259f0750ac7fabd19da1d8551e4c/src/librustc/ty/context.rs:2003
             at /rustc/f4a421ee3cf1259f0750ac7fabd19da1d8551e4c/src/librustc/ty/context.rs:1938
             at /rustc/f4a421ee3cf1259f0750ac7fabd19da1d8551e4c/src/librustc/ty/context.rs:2002
             at /rustc/f4a421ee3cf1259f0750ac7fabd19da1d8551e4c/src/librustc/ty/context.rs:1634
             at /rustc/f4a421ee3cf1259f0750ac7fabd19da1d8551e4c/src/librustc/ty/context.rs:2103
             at /rustc/f4a421ee3cf1259f0750ac7fabd19da1d8551e4c/src/librustc/ty/context.rs:2087
  14: rustc::ty::context::GlobalCtxt::enter_local
             at /rustc/f4a421ee3cf1259f0750ac7fabd19da1d8551e4c/src/librustc/ty/context.rs:2078
             at /rustc/f4a421ee3cf1259f0750ac7fabd19da1d8551e4c/src/librustc/ty/context.rs:2087
             at /rustc/f4a421ee3cf1259f0750ac7fabd19da1d8551e4c/src/librustc/ty/context.rs:2098
             at /rustc/f4a421ee3cf1259f0750ac7fabd19da1d8551e4c/src/librustc/ty/context.rs:1627
  15: rustc::traits::auto_trait::AutoTraitFinder::find_auto_trait_generics
             at /rustc/f4a421ee3cf1259f0750ac7fabd19da1d8551e4c/src/librustc/infer/mod.rs:525
             at /rustc/f4a421ee3cf1259f0750ac7fabd19da1d8551e4c/src/librustc/traits/auto_trait.rs:133
  16: rustdoc::clean::auto_trait::AutoTraitFinder::get_auto_trait_impl_for
             at src/librustdoc/clean/auto_trait.rs:200
             at src/librustdoc/clean/auto_trait.rs:123
  17: rustdoc::clean::auto_trait::AutoTraitFinder::get_auto_trait_impls
             at src/librustdoc/clean/auto_trait.rs:76
             at /rustc/f4a421ee3cf1259f0750ac7fabd19da1d8551e4c/src/libcore/option.rs:632
             at src/librustdoc/clean/auto_trait.rs:73
  18: rustdoc::clean::def_ctor::get_def_from_node_id
             at src/librustdoc/clean/auto_trait.rs:41
             at src/librustdoc/clean/def_ctor.rs:59
  19: <rustdoc::passes::collect_trait_impls::SyntheticImplCollector<'a, 'tcx, 'rcx, 'cstore> as rustdoc::fold::DocFolder>::fold_item
             at src/librustdoc/clean/auto_trait.rs:39
             at src/librustdoc/clean/mod.rs:3362
             at src/librustdoc/passes/collect_trait_impls.rs:170
  20: <alloc::vec::Vec<T> as alloc::vec::SpecExtend<T, I>>::from_iter
             at src/librustdoc/fold.rs:65
             at /rustc/f4a421ee3cf1259f0750ac7fabd19da1d8551e4c/src/libcore/iter/mod.rs:1589
             at /rustc/f4a421ee3cf1259f0750ac7fabd19da1d8551e4c/src/liballoc/vec.rs:1908
             at /rustc/f4a421ee3cf1259f0750ac7fabd19da1d8551e4c/src/liballoc/vec.rs:1805
             at /rustc/f4a421ee3cf1259f0750ac7fabd19da1d8551e4c/src/liballoc/vec.rs:1800
  21: rustdoc::fold::DocFolder::fold_inner_recur
             at /rustc/f4a421ee3cf1259f0750ac7fabd19da1d8551e4c/src/liballoc/vec.rs:1700
             at /rustc/f4a421ee3cf1259f0750ac7fabd19da1d8551e4c/src/libcore/iter/iterator.rs:1477
             at src/librustdoc/fold.rs:110
             at src/librustdoc/fold.rs:37
  22: <rustdoc::passes::collect_trait_impls::SyntheticImplCollector<'a, 'tcx, 'rcx, 'cstore> as rustdoc::fold::DocFolder>::fold_item
             at src/librustdoc/fold.rs:100
             at src/librustdoc/passes/collect_trait_impls.rs:178
  23: <alloc::vec::Vec<T> as alloc::vec::SpecExtend<T, I>>::from_iter
             at src/librustdoc/fold.rs:65
             at /rustc/f4a421ee3cf1259f0750ac7fabd19da1d8551e4c/src/libcore/iter/mod.rs:1589
             at /rustc/f4a421ee3cf1259f0750ac7fabd19da1d8551e4c/src/liballoc/vec.rs:1908
             at /rustc/f4a421ee3cf1259f0750ac7fabd19da1d8551e4c/src/liballoc/vec.rs:1805
             at /rustc/f4a421ee3cf1259f0750ac7fabd19da1d8551e4c/src/liballoc/vec.rs:1800
  24: rustdoc::fold::DocFolder::fold_inner_recur
             at /rustc/f4a421ee3cf1259f0750ac7fabd19da1d8551e4c/src/liballoc/vec.rs:1700
             at /rustc/f4a421ee3cf1259f0750ac7fabd19da1d8551e4c/src/libcore/iter/iterator.rs:1477
             at src/librustdoc/fold.rs:110
             at src/librustdoc/fold.rs:37
  25: <rustdoc::passes::collect_trait_impls::SyntheticImplCollector<'a, 'tcx, 'rcx, 'cstore> as rustdoc::fold::DocFolder>::fold_item
             at src/librustdoc/fold.rs:100
             at src/librustdoc/passes/collect_trait_impls.rs:178
  26: <alloc::vec::Vec<T> as alloc::vec::SpecExtend<T, I>>::from_iter
             at src/librustdoc/fold.rs:65
             at /rustc/f4a421ee3cf1259f0750ac7fabd19da1d8551e4c/src/libcore/iter/mod.rs:1589
             at /rustc/f4a421ee3cf1259f0750ac7fabd19da1d8551e4c/src/liballoc/vec.rs:1908
             at /rustc/f4a421ee3cf1259f0750ac7fabd19da1d8551e4c/src/liballoc/vec.rs:1805
             at /rustc/f4a421ee3cf1259f0750ac7fabd19da1d8551e4c/src/liballoc/vec.rs:1800
  27: rustdoc::fold::DocFolder::fold_inner_recur
             at /rustc/f4a421ee3cf1259f0750ac7fabd19da1d8551e4c/src/liballoc/vec.rs:1700
             at /rustc/f4a421ee3cf1259f0750ac7fabd19da1d8551e4c/src/libcore/iter/iterator.rs:1477
             at src/librustdoc/fold.rs:110
             at src/librustdoc/fold.rs:37
  28: <rustdoc::passes::collect_trait_impls::SyntheticImplCollector<'a, 'tcx, 'rcx, 'cstore> as rustdoc::fold::DocFolder>::fold_item
             at src/librustdoc/fold.rs:100
             at src/librustdoc/passes/collect_trait_impls.rs:178
  29: <alloc::vec::Vec<T> as alloc::vec::SpecExtend<T, I>>::from_iter
             at src/librustdoc/fold.rs:65
             at /rustc/f4a421ee3cf1259f0750ac7fabd19da1d8551e4c/src/libcore/iter/mod.rs:1589
             at /rustc/f4a421ee3cf1259f0750ac7fabd19da1d8551e4c/src/liballoc/vec.rs:1908
             at /rustc/f4a421ee3cf1259f0750ac7fabd19da1d8551e4c/src/liballoc/vec.rs:1805
             at /rustc/f4a421ee3cf1259f0750ac7fabd19da1d8551e4c/src/liballoc/vec.rs:1800
  30: rustdoc::fold::DocFolder::fold_inner_recur
             at /rustc/f4a421ee3cf1259f0750ac7fabd19da1d8551e4c/src/liballoc/vec.rs:1700
             at /rustc/f4a421ee3cf1259f0750ac7fabd19da1d8551e4c/src/libcore/iter/iterator.rs:1477
             at src/librustdoc/fold.rs:110
             at src/librustdoc/fold.rs:37
  31: <rustdoc::passes::collect_trait_impls::SyntheticImplCollector<'a, 'tcx, 'rcx, 'cstore> as rustdoc::fold::DocFolder>::fold_item
             at src/librustdoc/fold.rs:100
             at src/librustdoc/passes/collect_trait_impls.rs:178
  32: rustdoc::passes::collect_trait_impls::collect_trait_impls
             at src/librustdoc/fold.rs:115
             at /rustc/f4a421ee3cf1259f0750ac7fabd19da1d8551e4c/src/libcore/option.rs:632
             at src/librustdoc/fold.rs:115
             at src/librustdoc/passes/collect_trait_impls.rs:26
  33: rustdoc::core::run_core::{{closure}}::{{closure}}
             at src/librustdoc/core.rs:615
  34: rustc::ty::context::tls::enter_global
             at /rustc/f4a421ee3cf1259f0750ac7fabd19da1d8551e4c/src/librustc_driver/driver.rs:1353
             at /rustc/f4a421ee3cf1259f0750ac7fabd19da1d8551e4c/src/librustc/ty/context.rs:2035
             at /rustc/f4a421ee3cf1259f0750ac7fabd19da1d8551e4c/src/librustc/ty/context.rs:2003
             at /rustc/f4a421ee3cf1259f0750ac7fabd19da1d8551e4c/src/librustc/ty/context.rs:1938
             at /rustc/f4a421ee3cf1259f0750ac7fabd19da1d8551e4c/src/librustc/ty/context.rs:2002
             at /rustc/f4a421ee3cf1259f0750ac7fabd19da1d8551e4c/src/librustc/ty/context.rs:2034
             at /rustc/f4a421ee3cf1259f0750ac7fabd19da1d8551e4c/src/librustc/ty/context.rs:1992
             at /rustc/f4a421ee3cf1259f0750ac7fabd19da1d8551e4c/src/libstd/thread/local.rs:309
             at /rustc/f4a421ee3cf1259f0750ac7fabd19da1d8551e4c/src/libstd/thread/local.rs:255
             at /rustc/f4a421ee3cf1259f0750ac7fabd19da1d8551e4c/src/librustc/ty/context.rs:1984
             at /rustc/f4a421ee3cf1259f0750ac7fabd19da1d8551e4c/src/libstd/thread/local.rs:309
             at /rustc/f4a421ee3cf1259f0750ac7fabd19da1d8551e4c/src/libstd/thread/local.rs:255
             at /rustc/f4a421ee3cf1259f0750ac7fabd19da1d8551e4c/src/librustc/ty/context.rs:1976
             at /rustc/f4a421ee3cf1259f0750ac7fabd19da1d8551e4c/src/librustc/ty/context.rs:2014
  35: rustc::ty::context::TyCtxt::create_and_enter
             at /rustc/f4a421ee3cf1259f0750ac7fabd19da1d8551e4c/src/librustc/ty/context.rs:1216
  36: rustc_driver::driver::phase_3_run_analysis_passes
             at /rustc/f4a421ee3cf1259f0750ac7fabd19da1d8551e4c/src/librustc_driver/driver.rs:1261
  37: <scoped_tls::ScopedKey<T>>::set
             at src/librustdoc/core.rs:497
             at /rustc/f4a421ee3cf1259f0750ac7fabd19da1d8551e4c/src/librustc_driver/driver.rs:76
             at /cargo/registry/src/github.com-1ecc6299db9ec823/scoped-tls-0.1.2/src/lib.rs:155
  38: rustdoc::core::run_core
             at /rustc/f4a421ee3cf1259f0750ac7fabd19da1d8551e4c/src/librustc_driver/driver.rs:75
             at src/librustdoc/core.rs:404
  39: <scoped_tls::ScopedKey<T>>::set
             at src/librustdoc/lib.rs:425
             at /cargo/registry/src/github.com-1ecc6299db9ec823/scoped-tls-0.1.2/src/lib.rs:155
             at /rustc/f4a421ee3cf1259f0750ac7fabd19da1d8551e4c/src/libsyntax/lib.rs:123
             at /cargo/registry/src/github.com-1ecc6299db9ec823/scoped-tls-0.1.2/src/lib.rs:155
  40: syntax::with_globals
             at /rustc/f4a421ee3cf1259f0750ac7fabd19da1d8551e4c/src/libsyntax/lib.rs:122
  41: std::panicking::try::do_call
             at src/librustdoc/lib.rs:422
             at /rustc/f4a421ee3cf1259f0750ac7fabd19da1d8551e4c/src/librustc_driver/lib.rs:1642
             at /rustc/f4a421ee3cf1259f0750ac7fabd19da1d8551e4c/src/libstd/panic.rs:319
             at /rustc/f4a421ee3cf1259f0750ac7fabd19da1d8551e4c/src/libstd/panicking.rs:306
  42: __rust_maybe_catch_panic
             at src/libpanic_unwind/lib.rs:102
  43: rustc_driver::monitor
             at /rustc/f4a421ee3cf1259f0750ac7fabd19da1d8551e4c/src/libstd/panicking.rs:285
             at /rustc/f4a421ee3cf1259f0750ac7fabd19da1d8551e4c/src/libstd/panic.rs:398
             at /rustc/f4a421ee3cf1259f0750ac7fabd19da1d8551e4c/src/librustc_driver/lib.rs:1556
             at /rustc/f4a421ee3cf1259f0750ac7fabd19da1d8551e4c/src/librustc_driver/lib.rs:1567
             at /rustc/f4a421ee3cf1259f0750ac7fabd19da1d8551e4c/src/librustc_driver/lib.rs:1641
  44: rustdoc::main_args
             at src/librustdoc/lib.rs:422
             at src/librustdoc/lib.rs:385
  45: <scoped_tls::ScopedKey<T>>::set
             at src/librustdoc/lib.rs:108
             at /rustc/f4a421ee3cf1259f0750ac7fabd19da1d8551e4c/src/libcore/option.rs:424
             at src/librustdoc/lib.rs:108
             at /cargo/registry/src/github.com-1ecc6299db9ec823/scoped-tls-0.1.2/src/lib.rs:155
             at /rustc/f4a421ee3cf1259f0750ac7fabd19da1d8551e4c/src/libsyntax/lib.rs:123
             at /cargo/registry/src/github.com-1ecc6299db9ec823/scoped-tls-0.1.2/src/lib.rs:155
  46: syntax::with_globals
             at /rustc/f4a421ee3cf1259f0750ac7fabd19da1d8551e4c/src/libsyntax/lib.rs:122
  47: std::panicking::try::do_call
             at /rustc/f4a421ee3cf1259f0750ac7fabd19da1d8551e4c/src/libstd/thread/mod.rs:479
             at /rustc/f4a421ee3cf1259f0750ac7fabd19da1d8551e4c/src/libstd/panic.rs:319
             at /rustc/f4a421ee3cf1259f0750ac7fabd19da1d8551e4c/src/libstd/panicking.rs:306
  48: __rust_maybe_catch_panic
             at src/libpanic_unwind/lib.rs:102
  49: <F as alloc::boxed::FnBox<A>>::call_box
             at /rustc/f4a421ee3cf1259f0750ac7fabd19da1d8551e4c/src/libstd/panicking.rs:285
             at /rustc/f4a421ee3cf1259f0750ac7fabd19da1d8551e4c/src/libstd/panic.rs:398
             at /rustc/f4a421ee3cf1259f0750ac7fabd19da1d8551e4c/src/libstd/thread/mod.rs:478
             at /rustc/f4a421ee3cf1259f0750ac7fabd19da1d8551e4c/src/liballoc/boxed.rs:673
  50: std::sys::unix::thread::Thread::new::thread_start
             at /rustc/f4a421ee3cf1259f0750ac7fabd19da1d8551e4c/src/liballoc/boxed.rs:683
             at src/libstd/sys_common/thread.rs:24
             at src/libstd/sys/unix/thread.rs:91
  51: start_thread
  52: __clone

error: internal compiler error: unexpected panic

error: Unrecognized option: 'document-private-items'

error: Could not document `style`.

[QuietMisdreavus]

Aha, this is a problem with synthetic impls again. cc @Aaron1011 @nikomatsakis

Sadly, the PR which triggered this is mainly an upgrade from nightly-2018-10-05 to nightly-2018-12-14 and related code changes to bring Servo in line, so i'm not totally sure what is specifically raising this error. 😕

[SimonSapin]

Here is the rustdoc command as printed by cargo.

rustdoc-with-private is rustdoc -Z "unstable-options" --cap-lints warn --document-private-items "$@"

  process didn't exit successfully: `/home/simon/servo2/etc/rustdoc-with-private --crate-name style components/style/lib.rs --color always -o /home/simon/servo2/target/doc --cfg 'feature="arrayvec"' --cfg 'feature="crossbeam-channel"' --cfg 'feature="cssparser"' --cfg 'feature="encoding_rs"' --cfg 'feature="html5ever"' --cfg 'feature="malloc_size_of"' --cfg 'feature="serde"' --cfg 'feature="servo"' --cfg 'feature="servo_atoms"' --cfg 'feature="servo_config"' --cfg 'feature="servo_url"' --cfg 'feature="string_cache"' --cfg 'feature="style_traits"' -L dependency=/home/simon/servo2/target/debug/deps --extern app_units=/home/simon/servo2/target/debug/deps/libapp_units-ae87cf6200d5e636.rmeta --extern arrayvec=/home/simon/servo2/target/debug/deps/libarrayvec-6a3e5bbc1833ca95.rmeta --extern atomic_refcell=/home/simon/servo2/target/debug/deps/libatomic_refcell-51a3ef40ce2397a3.rmeta --extern bitflags=/home/simon/servo2/target/debug/deps/libbitflags-76ac00ec522d13ab.rmeta --extern byteorder=/home/simon/servo2/target/debug/deps/libbyteorder-8ede2409b36ea8f6.rmeta --extern cfg_if=/home/simon/servo2/target/debug/deps/libcfg_if-7a818f1ce8b10334.rmeta --extern crossbeam_channel=/home/simon/servo2/target/debug/deps/libcrossbeam_channel-6e8f3ebd4de0feec.rmeta --extern cssparser=/home/simon/servo2/target/debug/deps/libcssparser-7420765c7fcb8fa0.rmeta --extern encoding_rs=/home/simon/servo2/target/debug/deps/libencoding_rs-3703e4065da1dabd.rmeta --extern euclid=/home/simon/servo2/target/debug/deps/libeuclid-a189108eebc96eb9.rmeta --extern fallible=/home/simon/servo2/target/debug/deps/libfallible-e577df33116b4e99.rmeta --extern fxhash=/home/simon/servo2/target/debug/deps/libfxhash-5309f25945bebf1a.rmeta --extern hashglobe=/home/simon/servo2/target/debug/deps/libhashglobe-b413073f4a851867.rmeta --extern html5ever=/home/simon/servo2/target/debug/deps/libhtml5ever-12d1fd7ddaf95b35.rmeta --extern itertools=/home/simon/servo2/target/debug/deps/libitertools-c678761a8b3a6c1e.rmeta --extern itoa=/home/simon/servo2/target/debug/deps/libitoa-667b43f502e124dd.rmeta --extern lazy_static=/home/simon/servo2/target/debug/deps/liblazy_static-d92d0d4c3a8078bf.rmeta --extern log=/home/simon/servo2/target/debug/deps/liblog-ec0594db0536d389.rmeta --extern malloc_size_of=/home/simon/servo2/target/debug/deps/libmalloc_size_of-cbeccba4e88e7290.rmeta --extern malloc_size_of_derive=/home/simon/servo2/target/debug/deps/libmalloc_size_of_derive-5498ca7263650609.so --extern matches=/home/simon/servo2/target/debug/deps/libmatches-deef0144dc44c609.rmeta --extern debug_unreachable=/home/simon/servo2/target/debug/deps/libdebug_unreachable-9e230620fd8d13d3.rmeta --extern num_derive=/home/simon/servo2/target/debug/deps/libnum_derive-5b4c661c83661719.so --extern num_integer=/home/simon/servo2/target/debug/deps/libnum_integer-a0d23db758f6350e.rmeta --extern num_traits=/home/simon/servo2/target/debug/deps/libnum_traits-d992fcc879337d35.rmeta --extern ordered_float=/home/simon/servo2/target/debug/deps/libordered_float-1e9adf0c80de1c6f.rmeta --extern owning_ref=/home/simon/servo2/target/debug/deps/libowning_ref-fdd56e7ac0c44ac0.rmeta --extern parking_lot=/home/simon/servo2/target/debug/deps/libparking_lot-3333398224a44110.rmeta --extern precomputed_hash=/home/simon/servo2/target/debug/deps/libprecomputed_hash-76aae32f5ba3beba.rmeta --extern rayon=/home/simon/servo2/target/debug/deps/librayon-b8fa7942fd6dc2f8.rmeta --extern selectors=/home/simon/servo2/target/debug/deps/libselectors-5b9d10f8a97bdadf.rmeta --extern serde=/home/simon/servo2/target/debug/deps/libserde-4777277708f643a3.rmeta --extern servo_arc=/home/simon/servo2/target/debug/deps/libservo_arc-7a590b7c4f0134d1.rmeta --extern servo_atoms=/home/simon/servo2/target/debug/deps/libservo_atoms-013a3f7263a046e0.rmeta --extern servo_config=/home/simon/servo2/target/debug/deps/libservo_config-e8d32383d9eab38f.rmeta --extern servo_url=/home/simon/servo2/target/debug/deps/libservo_url-b7304442293a9a08.rmeta --extern smallbitvec=/home/simon/servo2/target/debug/deps/libsmallbitvec-7de92a07a0a0245a.rmeta --extern smallvec=/home/simon/servo2/target/debug/deps/libsmallvec-0eda9a67bfdf997e.rmeta --extern string_cache=/home/simon/servo2/target/debug/deps/libstring_cache-41e4f65266d31eb7.rmeta --extern style_derive=/home/simon/servo2/target/debug/deps/libstyle_derive-2402b5e8b31fc012.so --extern style_traits=/home/simon/servo2/target/debug/deps/libstyle_traits-7194c8b4143ce5fc.rmeta --extern thin_slice=/home/simon/servo2/target/debug/deps/libthin_slice-6c8c5c98346ae897.rmeta --extern time=/home/simon/servo2/target/debug/deps/libtime-1d2e0770d1dc1d66.rmeta --extern uluru=/home/simon/servo2/target/debug/deps/libuluru-9f38b4f588702e9b.rmeta --extern unicode_bidi=/home/simon/servo2/target/debug/deps/libunicode_bidi-daa8c68c24d3e006.rmeta --extern unicode_segmentation=/home/simon/servo2/target/debug/deps/libunicode_segmentation-14f8d301431397ac.rmeta --extern void=/home/simon/servo2/target/debug/deps/libvoid-777d0f5189f4bd4e.rmeta -Z treat-err-as-bug` (exit code: 1)

[QuietMisdreavus]

Based on trying it myself, i think the type at fault is PathParser here - at least that's the last one i get logs from before it bails.

[QuietMisdreavus]

If you want to try this yourself with a local rustdoc, i was able to clone Servo, check out the rustup branch, and run the following command to reproduce:

RUST_LOG=rustdoc::clean::auto_trait cargo +other rustdoc --manifest-path ports/servo/Cargo.toml -p style -- -Z unstable-options -Z treat-err-as-bug

May help in the absence of a reduced test case.

[Aaron1011]

Minimized reproduction:

struct Wrapper<T>(T);

trait MyTrait {
    type Output;
}

impl<'a, I, T: 'a> MyTrait for Wrapper<I>
    where I: MyTrait<Output=&'a T>
{
    type Output = T;
}

struct Inner<'a, T>(&'a T);

impl<'a, T> MyTrait for Inner<'a, T> {
    type Output = &'a T;
}


struct Parser<'a> {
    field: <Wrapper<Inner<'a, u8>> as MyTrait>::Output
}