Compiling repro-macro v0.0.0  Documenting repro v0.0.0 thread 'rustc' (46818762) panicked at src/librustdoc/html/highlight.rs:225:42: `exit_elem` called on empty class stack stack backtrace:  0: 0x111b5a1b0 - <std::sys::backtrace::BacktraceLock::print::DisplayBacktrace as core::fmt::Display>::fmt::h972240fd8fddf0c5  1: 0x10efb4a70 - core::fmt::write::hc4ce1a4f9b0fe243  2: 0x111b13234 - std::io::Write::write_fmt::h9dedd414d5aa6d6f  3: 0x111b253f4 - std::sys::backtrace::BacktraceLock::print::h6f19f5fdf018e813  4: 0x111b2bc8c - std::panicking::default_hook::{{closure}}::hf3816f6c1dc2ed6e  5: 0x111b2b92c - std::panicking::default_hook::h2c3b716c7f908774  6: 0x10fb5b6f8 - std[afe20e252829660a]::panicking::update_hook::<alloc[bc36f07fd14ea406]::boxed::Box<rustc_driver_impl[36bd8496901014dd]::install_ice_hook::{closure#1}>>::{closure#0}  7: 0x111b2c1b4 - std::panicking::panic_with_hook::h3dcc4d4095ad556a  8: 0x111b2be64 - std::panicking::panic_handler::{{closure}}::hf8946771d264106d  9: 0x111b25500 - std::sys::backtrace::__rust_end_short_backtrace::h7592b2729510c7e3  10: 0x111b099bc - __rustc[4463466e04a8a971]::rust_begin_unwind  11: 0x114892e20 - core::panicking::panic_fmt::h22b49dfc784232b7  12: 0x11489252c - core::option::expect_failed::h9bccb119ce1d83cb  13: 0x102db63d0 - rustdoc[63b0dfff8c6fb358]::html::highlight::write_code::<core[d3311d316bb0ed79]::fmt::Formatter>::{closure#2}  14: 0x102e716b0 - <rustdoc[63b0dfff8c6fb358]::html::highlight::Classifier>::advance  15: 0x102e720a0 - <rustdoc[63b0dfff8c6fb358]::html::highlight::Classifier>::highlight  16: 0x102d1c980 - rustdoc[63b0dfff8c6fb358]::html::highlight::write_code::<core[d3311d316bb0ed79]::fmt::Formatter>  17: 0x102f4c8b8 - <&core[d3311d316bb0ed79]::fmt::builders::FromFn<rustdoc[63b0dfff8c6fb358]::html::sources::print_src<&mut core[d3311d316bb0ed79]::fmt::Formatter>::{closure#0}> as core[d3311d316bb0ed79]::fmt::Display>::fmt  18: 0x10efb4a70 - core::fmt::write::hc4ce1a4f9b0fe243  19: 0x102f4ce0c - <&askama[22502a62a6e0aee7]::filters::escape::Safe<&core[d3311d316bb0ed79]::fmt::builders::FromFn<rustdoc[63b0dfff8c6fb358]::html::sources::print_src<&mut core[d3311d316bb0ed79]::fmt::Formatter>::{closure#0}>> as core[d3311d316bb0ed79]::fmt::Display>::fmt  20: 0x10efb4a70 - core::fmt::write::hc4ce1a4f9b0fe243  21: 0x102f19a90 - <rustdoc[63b0dfff8c6fb358]::html::sources::SourceCollector as rustdoc[63b0dfff8c6fb358]::visit::DocVisitor>::visit_item  22: 0x102e219d8 - <rustdoc[63b0dfff8c6fb358]::html::render::context::Context>::init  23: 0x102dbb028 - rustdoc[63b0dfff8c6fb358]::main_args::{closure#2}::{closure#0}  24: 0x102db0944 - rustc_interface[4b3a661e2b8d05a6]::interface::run_compiler::<(), rustdoc[63b0dfff8c6fb358]::main_args::{closure#2}>::{closure#1}  25: 0x102d2311c - std[afe20e252829660a]::sys::backtrace::__rust_begin_short_backtrace::<rustc_interface[4b3a661e2b8d05a6]::util::run_in_thread_with_globals<rustc_interface[4b3a661e2b8d05a6]::util::run_in_thread_pool_with_globals<rustc_interface[4b3a661e2b8d05a6]::interface::run_compiler<(), rustdoc[63b0dfff8c6fb358]::main_args::{closure#2}>::{closure#1}, ()>::{closure#0}, ()>::{closure#0}::{closure#0}, ()>  26: 0x102dd8b3c - <<std[afe20e252829660a]::thread::Builder>::spawn_unchecked_<rustc_interface[4b3a661e2b8d05a6]::util::run_in_thread_with_globals<rustc_interface[4b3a661e2b8d05a6]::util::run_in_thread_pool_with_globals<rustc_interface[4b3a661e2b8d05a6]::interface::run_compiler<(), rustdoc[63b0dfff8c6fb358]::main_args::{closure#2}>::{closure#1}, ()>::{closure#0}, ()>::{closure#0}::{closure#0}, ()>::{closure#1} as core[d3311d316bb0ed79]::ops::function::FnOnce<()>>::call_once::{shim:vtable#0}  27: 0x111b21fdc - std::sys::thread::unix::Thread::new::thread_start::h41048f3b076e32d9  28: 0x18a4abbc8 - __pthread_cond_wait error: the compiler unexpectedly panicked. this is a bug. note: compiler flags: --crate-type lib -Z unstable-options note: some of the compiler flags provided by cargo are hidden query stack during panic: end of query stack error: could not document `repro`