current nightly doesn't build example

[morriswinkler]

Issue

current nightly doesn't build example from https://rocket.rs/v0.4/guide/getting-started/
rustc 1.53.0-nightly (07e0e2ec2 2021-03-24)

tried with:
rocket = "0.4.7"
rocket = "0.4.6"

was also posted in rust-lang/rust#83710

Workaround

use cargo 1.52.0-nightly (572e20153 2021-02-24)

Stack Trace

thread 'rustc' panicked at 'found unstable fingerprints for predicates_of(core[40e9]::ops::function::Fn): GenericPredicates { parent: None, predicates: [(Binder(TraitPredicate(<Self as std::ops::FnMut>)), /Users/morris/.rustup/toolchains/nightly-x86_64-apple-darwin/lib/rustlib/src/rust/library/core/src/ops/function.rs:67:21: 67:32 (#0)), (Binder(TraitPredicate()), /Users/morris/.rustup/toolchains/nightly-x86_64-apple-darwin/lib/rustlib/src/rust/library/core/src/ops/function.rs:67:14: 67:18 (#0)), (Binder(TraitPredicate(<Self as std::ops::Fn>)), /Users/morris/.rustup/toolchains/nightly-x86_64-apple-darwin/lib/rustlib/src/rust/library/core/src/ops/function.rs:67:1: 67:32 (#0))] }', /rustc/07e0e2ec268c140e607e1ac7f49f145612d0f597/compiler/rustc_query_system/src/query/plumbing.rs:593:5
stack backtrace:
0: _rust_begin_unwind
1: std::panicking::begin_panic_fmt
2: rustc_query_system::query::plumbing::incremental_verify_ich
3: rustc_query_system::query::plumbing::load_from_disk_and_cache_in_memory
4: rustc_data_structures::stack::ensure_sufficient_stack
5: rustc_query_system::query::plumbing::get_query_impl
6: <rustc_query_impl::Queries as rustc_middle::ty::query::QueryEngine>::predicates_of
7: rustc_middle::ty::generics::GenericPredicates::instantiate_identity_into
8: rustc_middle::ty::generics::GenericPredicates::instantiate_identity
9: rustc_trait_selection::traits::object_safety::generics_require_sized_self
10: core::ops::function::impls::<impl core::ops::function::FnOnce for &mut F>::call_once
11: <core::iter::adapters::flatten::FlatMap<I,U,F> as core::iter::traits::iterator::Iterator>::next
12: <smallvec::SmallVec as core::iter::traits::collect::Extend<::Item>>::extend
13: rustc_arena::cold_path
14: rustc_middle::arena::Arena::alloc_from_iter
15: rustc_trait_selection::traits::vtable_methods
16: rustc_query_impl::<impl rustc_query_system::query::config::QueryAccessors<rustc_query_impl::plumbing::QueryCtxt> for rustc_query_impl::queries::vtable_methods>::compute
17: rustc_middle::dep_graph::::with_deps
18: rustc_query_system::query::plumbing::load_from_disk_and_cache_in_memory
19: rustc_data_structures::stack::ensure_sufficient_stack
20: rustc_query_system::query::plumbing::get_query_impl
21: <rustc_query_impl::Queries as rustc_middle::ty::query::QueryEngine>::vtable_methods
22: <rustc_mir::monomorphize::collector::MirNeighborCollector as rustc_middle::mir::visit::Visitor>::visit_rvalue
23: rustc_mir::monomorphize::collector::collect_neighbours
24: rustc_mir::monomorphize::collector::collect_items_rec
25: rustc_session::utils::::time
26: rustc_mir::monomorphize::collector::collect_crate_mono_items
27: rustc_mir::monomorphize::partitioning::collect_and_partition_mono_items
28: rustc_query_impl::<impl rustc_query_system::query::config::QueryAccessors<rustc_query_impl::plumbing::QueryCtxt> for rustc_query_impl::queries::collect_and_partition_mono_items>::compute
29: rustc_middle::dep_graph::::with_deps
30: rustc_query_system::dep_graph::graph::DepGraph::with_task_impl
31: rustc_data_structures::stack::ensure_sufficient_stack
32: rustc_query_system::query::plumbing::force_query_with_job
33: rustc_query_system::query::plumbing::get_query_impl
34: <rustc_query_impl::Queries as rustc_middle::ty::query::QueryEngine>::collect_and_partition_mono_items
35: <rustc_codegen_llvm::LlvmCodegenBackend as rustc_codegen_ssa::traits::backend::CodegenBackend>::codegen_crate
36: rustc_interface::passes::QueryContext::enter
37: rustc_interface::queries::Queries::ongoing_codegen
38: rustc_interface::queries::::enter
39: rustc_span::with_source_map
40: rustc_interface::interface::create_compiler_and_run
41: scoped_tls::ScopedKey::set
note: Some details are omitted, run with RUST_BACKTRACE=full for a verbose 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 1.53.0-nightly (07e0e2ec2 2021-03-24) running on x86_64-apple-darwin

note: compiler flags: -C embed-bitcode=no -C debuginfo=2 -C incremental --crate-type bin

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

query stack during panic:
#0 [predicates_of] computing predicates of std::ops::Fn
#1 [vtable_methods] finding all methods for trait std::ops::Fn
#2 [collect_and_partition_mono_items] collect_and_partition_mono_items
end of query stack

[jebrosen]

I don't think this is only affecting Rocket; the most relevant comment with a workaround seems to be: rust-lang/rust#83291 (comment)

EDIT: Or perhaps this: rust-lang/rust#83523 (comment)

[morriswinkler]

as mentioned by @jebrosen cargo clean -p <your_package_name> will fix that issue