ICE building docs of some crates in beta

[pietroalbini]

When building the documentation (or running the doctests) of a few crates, such as libsecp256k1, in beta or nightly, rustdoc crashes with this message (while it works fine on stable, even if with some pulldown warnings):

thread 'rustc' panicked at '/checkout/src/librustc/lint/context.rs:1049: failed to process bufferd lint here', /checkout/src/librustc/session/mod.rs:1130:26
note: Some details are omitted, run with `RUST_BACKTRACE=full` for a verbose backtrace.
stack backtrace:
   0: std::sys::unix::backtrace::tracing::imp::unwind_backtrace
             at /checkout/src/libstd/sys/unix/backtrace/tracing/gcc_s.rs:49
   1: std::sys_common::backtrace::print
             at /checkout/src/libstd/sys_common/backtrace.rs:68
             at /checkout/src/libstd/sys_common/backtrace.rs:57
   2: std::panicking::default_hook::{{closure}}
             at /checkout/src/libstd/panicking.rs:381
   3: std::panicking::default_hook
             at /checkout/src/libstd/panicking.rs:391
   4: std::panicking::rust_panic_with_hook
             at /checkout/src/libstd/panicking.rs:577
   5: std::panicking::begin_panic
   6: rustc::ty::context::tls::with_opt
   7: rustc::session::span_bug_fmt
   8: rustc::lint::context::check_ast_crate
   9: rustc_driver::driver::phase_2_configure_and_expand
             at /checkout/src/librustc_driver/driver.rs:909
  10: rustdoc::core::run_core
             at /checkout/src/librustdoc/core.rs:161

error: Could not document `libsecp256k1`.

• Crate libsecp256k1 regressed from stable to beta (crater log caused by doctests).
• Crate oftlisp-anf regressed from stable to beta (crater log caused by doctests).

cc @sorpaas

[pietroalbini]

Crate oftlisp-anf is also affected, cc @remexre

[Mark-Simulacrum]

@rust-lang/dev-tools Can someone investigate and see if we can fix this?

[GuillaumeGomez]

I'll give it a look.

[GuillaumeGomez]

Both cargo test and cargo doc worked just fine for me...

> rustdoc --version
rustdoc 1.25.0-nightly (21882aad7 2018-01-28)

[QuietMisdreavus]

I ran cargo doc on libsecp256k1 on my own system without updating my nightly and hit the ICE:

$ rustdoc +nightly --version
rustdoc 1.25.0-nightly (ae920dcc9 2018-01-22)