"impossible case reached" while run cargo doc for package "typenum"

[Aloxaf]

rustc panicked while i ran cargo doc.

I tried this code:

> cargo new -- bin crash
     Created binary (application) `crash` project
> cd crash
> cargo add typenum
      Adding typenum v1.10.0 to dependencies
> cargo doc
    Updating `git://mirrors.ustc.edu.cn/crates.io-index` index
   Compiling typenum v1.10.0                                                                                                                                                
 Documenting typenum v1.10.0                                                                                                                                                
error: internal compiler error: librustc/traits/structural_impls.rs:178: impossible case reached                                                                            
                                                                                                                                                                            
thread '<unnamed>' panicked at 'Box<Any>', librustc_errors/lib.rs:599:9                                                                                                     
note: Run with `RUST_BACKTRACE=1` for a backtrace.                                                                                                                          
                                                                                                                                                                            
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 1.30.0-nightly (63c75d375 2018-09-21) running on x86_64-unknown-linux-gnu                                                                                       
                                                                                                                                                                            
error: Could not document `typenum`.                                                                                                                                        

Caused by:
  process didn't exit successfully: `rustdoc --crate-name typenum /home/aloxaf/.cargo/registry/src/mirrors.ustc.edu.cn-61ef6e0cd06fb9b8/typenum-1.10.0/src/lib.rs --cap-lints allow --color always -o /tmp/crash/target/doc -L dependency=/tmp/crash/target/debug/deps` (exit code: 1)

Meta

rustc --version --verbose:

rustc 1.30.0-nightly (63c75d375 2018-09-21)
binary: rustc
commit-hash: 63c75d375d76d0bcc586f9cb5520ced24bc58450
commit-date: 2018-09-21
host: x86_64-unknown-linux-gnu
release: 1.30.0-nightly
LLVM version: 8.0

Backtrace:

 Documenting typenum v1.10.0                                                                                                                                                
error: internal compiler error: librustc/traits/structural_impls.rs:178: impossible case reached                                                                            
                                                                                                                                                                            
thread '<unnamed>' panicked at 'Box<Any>', librustc_errors/lib.rs:599:9                                                                                                     
stack backtrace:                                                                                                                                                            
   0: std::sys::unix::backtrace::tracing::imp::unwind_backtrace                                                                                                             
             at libstd/sys/unix/backtrace/tracing/gcc_s.rs:49                                                                                                               
   1: std::sys_common::backtrace::print                                                                                                                                     
             at libstd/sys_common/backtrace.rs:71                                                                                                                           
             at libstd/sys_common/backtrace.rs:59                                                                                                                           
   2: std::panicking::default_hook::{{closure}}                                                                                                                             
             at libstd/panicking.rs:211                                                                                                                                     
   3: std::panicking::default_hook                                                                                                                                          
             at libstd/panicking.rs:227                                                                                                                                     
   4: std::panicking::rust_panic_with_hook                                                                                                                                  
             at libstd/panicking.rs:477                                                                                                                                     
   5: std::panicking::begin_panic                                                                                                                                           
   6: rustc_errors::Handler::bug                                                                                                                                            
   7: rustc::util::bug::opt_span_bug_fmt::{{closure}}                                                                                                                       
   8: rustc::ty::context::tls::with_opt::{{closure}}                                                                                                                        
   9: rustc::ty::context::tls::with_context_opt                                                                                                                             
  10: rustc::ty::context::tls::with_opt                                                                                                                                     
  11: rustc::util::bug::opt_span_bug_fmt                                                                                                                                    
  12: rustc::util::bug::bug_fmt                                                                                                                                             
  13: rustc::traits::structural_impls::<impl rustc::ty::context::Lift<'tcx> for rustc::traits::SelectionError<'a>>::lift_to_tcx                                             
  14: rustc::ty::context::TyCtxt::lift_to_global                                                                                                                            
  15: rustc::traits::select::SelectionContext::candidate_from_obligation                                                                                                    
  16: rustc::traits::select::SelectionContext::evaluate_stack                                                                                                               
  17: rustc::dep_graph::graph::DepGraph::with_anon_task                                                                                                                     
  18: rustc::traits::select::SelectionContext::evaluate_predicate_recursively                                                                                               
  19: rustc::infer::InferCtxt::probe                                                                                                                                        
  20: <&'a mut I as core::iter::iterator::Iterator>::next                                                                                                                   
  21: <alloc::vec::Vec<T> as alloc::vec::SpecExtend<T, I>>::from_iter                                                                                                       
  22: rustc::traits::select::SelectionContext::candidate_from_obligation_no_cache                                                                                           
  23: rustc::dep_graph::graph::DepGraph::with_anon_task                                                                                                                     
  24: rustc::traits::select::SelectionContext::candidate_from_obligation                                                                                                    
  25: rustc::traits::select::SelectionContext::evaluate_stack                                                                                                               
  26: rustc::dep_graph::graph::DepGraph::with_anon_task                                                                                                                     
  27: rustc::traits::select::SelectionContext::evaluate_predicate_recursively                                                                                               
  28: rustc::infer::InferCtxt::probe                                                                                                                                        
  29: <&'a mut I as core::iter::iterator::Iterator>::next                                                                                                                   
  30: <alloc::vec::Vec<T> as alloc::vec::SpecExtend<T, I>>::from_iter                                                                                                       
  31: rustc::traits::select::SelectionContext::candidate_from_obligation_no_cache                                                                                           
  32: rustc::dep_graph::graph::DepGraph::with_anon_task                                                                                                                     
  33: rustc::traits::select::SelectionContext::candidate_from_obligation                                                                                                    
  34: rustc::traits::select::SelectionContext::evaluate_stack                                                                                                               
  35: rustc::dep_graph::graph::DepGraph::with_anon_task                                                                                                                     
  36: rustc::traits::select::SelectionContext::evaluate_predicate_recursively                                                                                               
  37: rustc::infer::InferCtxt::probe                                                                                                                                        
  38: <&'a mut I as core::iter::iterator::Iterator>::next                                                                                                                   
  39: <alloc::vec::Vec<T> as alloc::vec::SpecExtend<T, I>>::from_iter                                                                                                       
  40: rustc::traits::select::SelectionContext::candidate_from_obligation_no_cache                                                                                           
  41: rustc::dep_graph::graph::DepGraph::with_anon_task                                                                                                                     
  42: rustc::traits::select::SelectionContext::candidate_from_obligation                                                                                                    
  43: rustc::traits::select::SelectionContext::evaluate_stack                                                                                                               
  44: rustc::dep_graph::graph::DepGraph::with_anon_task                                                                                                                     
  45: rustc::traits::select::SelectionContext::evaluate_predicate_recursively                                                                                               
  46: rustc::infer::InferCtxt::probe                                                                                                                                        
  47: <&'a mut I as core::iter::iterator::Iterator>::next                                                                                                                   
  48: <alloc::vec::Vec<T> as alloc::vec::SpecExtend<T, I>>::from_iter                                                                                                       
  49: rustc::traits::select::SelectionContext::candidate_from_obligation_no_cache                                                                                           
  50: rustc::dep_graph::graph::DepGraph::with_anon_task                                                                                                                     
  51: rustc::traits::select::SelectionContext::candidate_from_obligation                                                                                                    
  52: rustc::traits::select::SelectionContext::evaluate_stack                                                                                                               
  53: rustc::dep_graph::graph::DepGraph::with_anon_task                                                                                                                     
  54: rustc::traits::select::SelectionContext::evaluate_predicate_recursively                                                                                               
  55: rustc::infer::InferCtxt::probe                                                                                                                                        
  56: <&'a mut I as core::iter::iterator::Iterator>::next                                                                                                                   
  57: <alloc::vec::Vec<T> as alloc::vec::SpecExtend<T, I>>::from_iter                                                                                                       
  58: rustc::traits::select::SelectionContext::candidate_from_obligation_no_cache                                                                                           
  59: rustc::dep_graph::graph::DepGraph::with_anon_task                                                                                                                     
  60: rustc::traits::select::SelectionContext::candidate_from_obligation                                                                                                    
  61: rustc::traits::select::SelectionContext::evaluate_stack                                                                                                               
  62: rustc::dep_graph::graph::DepGraph::with_anon_task                                                                                                                     
  63: rustc::traits::select::SelectionContext::evaluate_predicate_recursively                                                                                               
  64: rustc::infer::InferCtxt::probe                                                                                                                                        
  65: <&'a mut I as core::iter::iterator::Iterator>::next                                                                                                                   
  66: <alloc::vec::Vec<T> as alloc::vec::SpecExtend<T, I>>::from_iter                                                                                                       
  67: rustc::traits::select::SelectionContext::candidate_from_obligation_no_cache                                                                                           
  68: rustc::dep_graph::graph::DepGraph::with_anon_task                                                                                                                     
  69: rustc::traits::select::SelectionContext::candidate_from_obligation                                                                                                    
  70: rustc::traits::select::SelectionContext::evaluate_stack                                                                                                               
  71: rustc::dep_graph::graph::DepGraph::with_anon_task                                                                                                                     
  72: rustc::traits::select::SelectionContext::evaluate_predicate_recursively                                                                                               
  73: rustc::infer::InferCtxt::probe                                                                                                                                        
  74: <&'a mut I as core::iter::iterator::Iterator>::next                                                                                                                   
  75: <alloc::vec::Vec<T> as alloc::vec::SpecExtend<T, I>>::from_iter                                                                                                       
  76: rustc::traits::select::SelectionContext::candidate_from_obligation_no_cache                                                                                           
  77: rustc::dep_graph::graph::DepGraph::with_anon_task                                                                                                                     
  78: rustc::traits::select::SelectionContext::candidate_from_obligation                                                                                                    
  79: rustc::traits::select::SelectionContext::evaluate_stack                                                                                                               
  80: rustc::dep_graph::graph::DepGraph::with_anon_task                                                                                                                     
  81: rustc::traits::select::SelectionContext::evaluate_predicate_recursively                                                                                               
  82: rustc::infer::InferCtxt::probe                                                                                                                                        
  83: <&'a mut I as core::iter::iterator::Iterator>::next                                                                                                                   
  84: <alloc::vec::Vec<T> as alloc::vec::SpecExtend<T, I>>::from_iter                                                                                                       
  85: rustc::traits::select::SelectionContext::candidate_from_obligation_no_cache                                                                                           
  86: rustc::dep_graph::graph::DepGraph::with_anon_task                                                                                                                     
  87: rustc::traits::select::SelectionContext::candidate_from_obligation                                                                                                    
  88: rustc::traits::select::SelectionContext::evaluate_stack                                                                                                               
  89: rustc::dep_graph::graph::DepGraph::with_anon_task                                                                                                                     
  90: rustc::traits::select::SelectionContext::evaluate_predicate_recursively                                                                                               
  91: rustc::infer::InferCtxt::probe                                                                                                                                        
  92: <&'a mut I as core::iter::iterator::Iterator>::next                                                                                                                   
  93: <alloc::vec::Vec<T> as alloc::vec::SpecExtend<T, I>>::from_iter                                                                                                       
  94: rustc::traits::select::SelectionContext::candidate_from_obligation_no_cache                                                                                           
  95: rustc::dep_graph::graph::DepGraph::with_anon_task                                                                                                                     
  96: rustc::traits::select::SelectionContext::candidate_from_obligation                                                                                                    
  97: rustc::traits::select::SelectionContext::evaluate_stack                                                                                                               
  98: rustc::dep_graph::graph::DepGraph::with_anon_task                                                                                                                     
  99: rustc::traits::select::SelectionContext::evaluate_predicate_recursively                                                                                               
                                                                                                                                                                            
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 1.30.0-nightly (63c75d375 2018-09-21) running on x86_64-unknown-linux-gnu                                                                                       
                                                                                                                                                                            
error: Could not document `typenum`.                                                                                                                                        

Caused by:
  process didn't exit successfully: `rustdoc --crate-name typenum /home/aloxaf/.cargo/registry/src/mirrors.ustc.edu.cn-61ef6e0cd06fb9b8/typenum-1.10.0/src/lib.rs --cap-lints allow --color always -o /tmp/crash/target/doc -L dependency=/tmp/crash/target/debug/deps` (exit code: 1)

[phansch]

This seems to be a duplicate of #53505

[Aloxaf]

This seems to be a duplicate of #53505

You are right. Thank you.