Rustc nightly panic when running clippy: tried to cache X, but was already existing as Y

[brinchj]

After an update to nightly today I ran clippy on my code as usual. However, this time it gave a rustc panic. I was not able to find an existing bug for this with a quick search, but one may exist :)

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rustc +nightly --version --verbose:
rustc 1.26.0-nightly (3926453 2018-03-15)
binary: rustc
commit-hash: 3926453
commit-date: 2018-03-15
host: x86_64-unknown-linux-gnu
release: 1.26.0-nightly
LLVM version: 6.0

cargo +nightly clippy -- --version --verbose:
0.0.188

Backtrace:

error: internal compiler error: librustc/ty/context.rs:976: tried to cache DefId(0/0:473 ~ foo[5ab1]::main[0]::RS[0]::LOC[0]), but was already existing as AllocId(
    1668
)

thread 'rustc' panicked at 'Box<Any>', librustc_errors/lib.rs:540:9
stack backtrace:
   0:     0x7fd54b792df3 - std::sys::unix::backtrace::tracing::imp::unwind_backtrace::h6a0bc5605dce4433
                               at libstd/sys/unix/backtrace/tracing/gcc_s.rs:49
   1:     0x7fd54b789ca4 - std::sys_common::backtrace::_print::h221d36b236e12e74
                               at libstd/sys_common/backtrace.rs:71
   2:     0x7fd54b78f68d - std::panicking::default_hook::{{closure}}::h6e8674dc74aeedd4
                               at libstd/sys_common/backtrace.rs:59
                               at libstd/panicking.rs:207
   3:     0x7fd54b78f389 - std::panicking::default_hook::h746ce9d1b7bb055c
                               at libstd/panicking.rs:223
   4:     0x7fd54c6e261d - core::ops::function::Fn::call::hb510ff0d959ce38b
   5:     0x7fd54b78fb29 - std::panicking::rust_panic_with_hook::h9a379049fd32d0d9
                               at libstd/panicking.rs:403
   6:     0x7fd54bec0bea - std::panicking::begin_panic::hef985c972aedad24
   7:     0x7fd54bee1da5 - rustc_errors::Handler::bug::hd04d670de9a4f7bc
   8:     0x7fd54c9f6e1f - rustc::session::opt_span_bug_fmt::{{closure}}::h9717c5174ccf7dbc
   9:     0x7fd54cab4065 - rustc::ty::context::tls::with_opt::{{closure}}::h2ab3fb2a7fdf1463
  10:     0x7fd54c6dae9f - <std::thread::local::LocalKey<T>>::try_with::h4a96d45c0fd1da65
  11:     0x7fd54c6daad6 - <std::thread::local::LocalKey<T>>::with::h935c0307e72b02b5
  12:     0x7fd54cab3e66 - rustc::ty::context::tls::with::ha5ff3dff40c0ca13
  13:     0x7fd54cab4017 - rustc::ty::context::tls::with_opt::h6c692edeed5f4205
  14:     0x7fd54c9f6d24 - rustc::session::opt_span_bug_fmt::hd4ef20e4f17440e1
  15:     0x7fd54c9f6c96 - rustc::session::bug_fmt::h3e8fd5409ad66756
  16:     0x7fd54caae9da - rustc::ty::context::InterpretInterner::cache::h1887c6eea8e42f39
  17:     0x7fd54ca8be7e - <rustc::ty::maps::on_disk_cache::CacheDecoder<'a, 'tcx, 'x> as serialize::serialize::SpecializedDecoder<rustc::mir::interpret::AllocId>>::specialized_decode::h7272271c1d82beca
  18:     0x7fd54cafded6 - <rustc::mir::interpret::MemoryPointer as serialize::serialize::Decodable>::decode::{{closure}}::h95abfc00fa88786f
  19:     0x7fd54c8593f9 - serialize::serialize::Decoder::read_enum_variant::h237634adb88347ef
  20:     0x7fd54cafda8f - <rustc::mir::interpret::value::Pointer as serialize::serialize::Decodable>::decode::{{closure}}::hd8074276f09679f8
  21:     0x7fd54c85a79b - serialize::serialize::Decoder::read_enum_variant::hf44cd3f2c6c882d2
  22:     0x7fd54c8595ff - serialize::serialize::Decoder::read_enum_variant::h9259904540d0ee8d
  23:     0x7fd54cb9177a - rustc::ty::maps::<impl rustc::ty::maps::queries::const_eval<'tcx>>::try_get::h0fd12e21b00a6c19
  24:     0x7fd54cc8685a - rustc::ty::maps::TyCtxtAt::const_eval::hb868ce2a5cc81181
  25:     0x7fd54cc82e74 - rustc::ty::maps::<impl rustc::ty::context::TyCtxt<'a, 'tcx, 'lcx>>::const_eval::h8866ca29889b7ee8
  26:     0x7fd548e01b19 - rustc_mir::monomorphize::collector::collect_items_rec::h984ce9e45fc5814d
  27:     0x7fd548e02f31 - rustc_mir::monomorphize::collector::collect_items_rec::h984ce9e45fc5814d
  28:     0x7fd548e02f31 - rustc_mir::monomorphize::collector::collect_items_rec::h984ce9e45fc5814d
  29:     0x7fd548e01492 - rustc_mir::monomorphize::collector::collect_crate_mono_items::h6512adb9d11b1126
  30:     0x7fd5426fc528 - rustc_trans::base::collect_and_partition_translation_items::h16e489be9a70c8bc
  31:     0x7fd54c87fdb9 - rustc::dep_graph::graph::DepGraph::with_task_impl::h7bb0171e1fb0b345
  32:     0x7fd54cc5ab97 - rustc::ty::maps::<impl rustc::ty::maps::queries::collect_and_partition_translation_items<'tcx>>::force::ha1e3871a6ee96b55
  33:     0x7fd54cc5bbe8 - rustc::ty::maps::<impl rustc::ty::maps::queries::collect_and_partition_translation_items<'tcx>>::try_get::h8a39ec230dc612c4
  34:     0x7fd54cc8b2e5 - rustc::ty::maps::TyCtxtAt::collect_and_partition_translation_items::hbcd28dffa92ca525
  35:     0x7fd54cc8413e - rustc::ty::maps::<impl rustc::ty::context::TyCtxt<'a, 'tcx, 'lcx>>::collect_and_partition_translation_items::h51816eb64a8d161f
  36:     0x7fd5426f7f33 - rustc_trans::base::trans_crate::h7aad30be39f12db7
  37:     0x7fd5427502e7 - <rustc_trans::LlvmTransCrate as rustc_trans_utils::trans_crate::TransCrate>::trans_crate::h2fc85b08340ba786
  38:     0x7fd54d6bea8c - rustc_driver::driver::phase_4_translate_to_llvm::hedf678c6a2658a09
  39:     0x7fd54d6b73de - rustc_driver::driver::compile_input::{{closure}}::h7a79a9d8c1ffdd5f
  40:     0x7fd54d643247 - rustc::ty::context::TyCtxt::create_and_enter::h0c78163ea978eb0d
  41:     0x7fd54d6b5401 - rustc_driver::driver::compile_input::haf2922d1e945b5b0
  42:     0x7fd54d6d25e5 - rustc_driver::run_compiler::h884712936ee0cb5b
  43:     0x55686831a8e2 - std::sys_common::backtrace::__rust_begin_short_backtrace::h1f219268cfc4e6d3
  44:     0x55686831ad7b - std::panicking::try::do_call::hfd92181ad0f55388
  45:     0x7fd54b7a898e - __rust_maybe_catch_panic
                               at libpanic_unwind/lib.rs:102
  46:     0x5568683127ad - <F as alloc::boxed::FnBox<A>>::call_box::h0c116730c83a0489
  47:     0x7fd54b79fbeb - std::sys::unix::thread::Thread::new::thread_start::h9e86927e52b61050
                               at /checkout/src/liballoc/boxed.rs:793
                               at libstd/sys_common/thread.rs:24
                               at libstd/sys/unix/thread.rs:90
  48:     0x7fd54b5096b9 - start_thread
  49:     0x7fd54b02941c - clone
  50:                0x0 - <unknown>

note: the compiler unexpectedly panicked. this is a bug.

note: we would appreciate a bug report: /~https://github.com/rust-lang/rust/blob/master/CONTRIBUTING.md#bug-reports

note: rustc 1.26.0-nightly (392645394 2018-03-15) running on x86_64-unknown-linux-gnu

note: compiler flags: -C debuginfo=2 -C incremental -C link-arg=-Wl,--no-gc-sections --crate-type bin

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

[brinchj]

I just ran cargo clean and it solved my immediate issue which may have been caused by a bad local cache?

[oli-obk]

dupe of #49081