rustdoc: rustc panicked at 'assertion failed: !self.is_proc_macro(item_id)'

[fluxxu]

rustdoc panic while generating documentation

Reproduce:

• diesel_codegen = { version = "0.9.0" }
• #![feature(proc_macro)]
• #[macro_use] extern crate diesel_codegen;
• pub use <whatever>;
• cargo doc

I made a minimal example here:
https://github.com/fluxxu/rustdoc-issue

I expected to see this happen: documentation generated

Instead, this happened:

thread 'rustc' panicked at 'assertion failed: !self.is_proc_macro(item_id)', C:\bot\slave\nightly-dist-rustc-win-msvc-64\build\src\librustc_metadata\decoder.rs:523

Backtrace

thread 'rustc' panicked at 'assertion failed: !self.is_proc_macro(item_id)', C:\bot\slave\nightly-dist-rustc-win-msvc-64\build\src\librustc_metadata\decoder.rs:523
stack backtrace:
   0:     0x7fffc324edaa - std::panicking::Location::line::h3f91a23a140528f1
   1:     0x7fffc324e234 - std::panicking::Location::line::h3f91a23a140528f1
   2:     0x7fffc3251c8d - std::panicking::rust_panic_with_hook::h7e1d2cc288a6d6e6
   3:     0x7fffbce05229 - <unknown>
   4:     0x7fffbce743f0 - rustc_metadata::decoder::<impl rustc_metadata::cstore::CrateMetadata>::entry::hb1a80ffab1c26775
   5:     0x7fffbce76ba7 - rustc_metadata::decoder::<impl rustc_metadata::cstore::CrateMetadata>::get_visibility::hed8ab8e78c5d211c
   6:     0x7fffbce7717c - rustc_metadata::decoder::<impl rustc_metadata::cstore::CrateMetadata>::get_impl_trait::h82138501e2416767
   7:     0x7fffbce80369 - rustc_metadata::cstore_impl::<impl rustc::middle::cstore::CrateStore<'tcx> for rustc_metadata::cstore::CStore>::impl_trait_ref::h8de74aa911835a28
   8:     0x7fffb702f3f1 - rustc::ty::<impl rustc::ty::context::TyCtxt<'a, 'gcx, 'tcx>>::impl_trait_ref::hfb1edfda95a13315
   9:     0x7fffd2e866f3 - rustdoc::clean::inline::build_impl::h53c2f0f1eb945e58
  10:     0x7fffd2e86023 - rustdoc::clean::inline::build_impls::h13bbf40f3f04e450
  11:     0x7fffd2e813f4 - rustdoc::clean::inline::try_inline::h58b3a816a2eb28de
  12:     0x7fffd2e80adf - rustdoc::clean::inline::try_inline::h58b3a816a2eb28de
  13:     0x7fffd2eae888 - <rustdoc::doctree::Import as rustdoc::clean::Clean<collections::vec::Vec<rustdoc::clean::Item>>>::clean::h8bae7a1765e79682
  14:     0x7fffd2e8e634 - <rustdoc::doctree::Module as rustdoc::clean::Clean<rustdoc::clean::Item>>::clean::h218d3de5ed973d32
  15:     0x7fffd2e7baaa - <unknown>
  16:     0x7fffd2e8ee7f - <rustdoc::doctree::Module as rustdoc::clean::Clean<rustdoc::clean::Item>>::clean::h218d3de5ed973d32
  17:     0x7fffd2e7baaa - <unknown>
  18:     0x7fffd2e8ee7f - <rustdoc::doctree::Module as rustdoc::clean::Clean<rustdoc::clean::Item>>::clean::h218d3de5ed973d32
  19:     0x7fffd2e8b209 - <rustdoc::visit_ast::RustdocVisitor<'a, 'tcx> as rustdoc::clean::Clean<rustdoc::clean::Crate>>::clean::h81959a1f562bc98e
  20:     0x7fffd2eb8d97 - rustdoc::core::run_core::h4b58c98803e5877c
  21:     0x7fffd2ddb27f - <unknown>
  22:     0x7fffd2e31d48 - <unknown>
  23:     0x7fffd2eb61ec - rustdoc::core::run_core::h4b58c98803e5877c
  24:     0x7fffd2dfec4d - <unknown>
  25:     0x7fffc3254611 - _rust_maybe_catch_panic
  26:     0x7fffd2e2301b - <unknown>
  27:     0x7fffc324c2fe - std::sys::imp::thread::Thread::new::hb29119a6ae6621b3
  28:     0x7fffe97e8363 - BaseThreadInitThunk

error: Could not document `s2`.

Caused by:
  process didn't exit successfully: `rustdoc --crate-name s2 src\lib.rs -o C:\Users\fluxx\Projects\s2\target\doc -L dependency=C:\Users\fluxx\Projects\s2\target\debug\deps --extern rand=C:\Users\fluxx\Projects\s2\target\debug\deps\librand-26cfd8d095643d5f.rlib --extern error_chain=C:\Users\fluxx\Projects\s2\target\debug\deps\liberror_chain-c70cadd7b5aa5bb1.rlib --extern lazy_static=C:\Users\fluxx\Projects\s2\target\debug\deps\liblazy_static-558fd24daf596ca5.rlib --extern crypto=C:\Users\fluxx\Projects\s2\target\debug\deps\libcrypto-84c1bd1acc23cedb.rlib --extern uuid=C:\Users\fluxx\Projects\s2\target\debug\deps\libuuid-3b9ce1f07977469a.rlib --extern router=C:\Users\fluxx\Projects\s2\target\debug\deps\librouter-1ec5c88e036a1c55.rlib --extern staticfile=C:\Users\fluxx\Projects\s2\target\debug\deps\libstaticfile-71a9fe52eddc1691.rlib --extern serde_json=C:\Users\fluxx\Projects\s2\target\debug\deps\libserde_json-99385da38ca59b91.rlib --extern base64=C:\Users\fluxx\Projects\s2\target\debug\deps\libbase64-703ed5cb661c42b8.rlib --extern serde_derive=C:\Users\fluxx\Projects\s2\target\debug\deps\serde_derive-f9682affc7dd49fb.dll --extern diesel_codegen=C:\Users\fluxx\Projects\s2\target\debug\deps\diesel_codegen-b5b438de9650d88f.dll --extern serde=C:\Users\fluxx\Projects\s2\target\debug\deps\libserde-f5bb5456e04e9a13.rlib --extern chrono=C:\Users\fluxx\Projects\s2\target\debug\deps\libchrono-df04c67c2203866e.rlib --extern diesel=C:\Users\fluxx\Projects\s2\target\debug\deps\libdiesel-bd497f9a6d56d1ca.rlib --extern iron=C:\Users\fluxx\Projects\s2\target\debug\deps\libiron-43102b3f2688c72f.rlib --extern dotenv=C:\Users\fluxx\Projects\s2\target\debug\deps\libdotenv-c0d2b5ada142d175.rlib` (exit code: 101)

Meta

rustc 1.15.0-nightly (71c06a56a 2016-12-18)
binary: rustc
commit-hash: 71c06a56a120a0d5e3b224105ee3e6754f83e5fa
commit-date: 2016-12-18
host: x86_64-pc-windows-msvc
release: 1.15.0-nightly
LLVM version: 3.9

[arielb1]

Is this fixed on the newer betas?

[nikomatsakis]

cc @jseyfried

[nikomatsakis]

triage: P-high

@jseyfried thinks it's already fixed though

[jseyfried]

This is #38237 -- fixed in #38537 and backported to beta in #38872.
I verified that https://github.com/fluxxu/rustdoc-issue works on beta and nightly.