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Remove incorrect assert #79976

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Dec 13, 2020
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Remove incorrect assert #79976

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2 changes: 1 addition & 1 deletion src/librustdoc/passes/collect_intra_doc_links.rs
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Original file line number Diff line number Diff line change
Expand Up @@ -436,8 +436,8 @@ impl<'a, 'tcx> LinkCollector<'a, 'tcx> {
// Try looking for methods and associated items.
let mut split = path_str.rsplitn(2, "::");
// NB: `split`'s first element is always defined, even if the delimiter was not present.
// NB: `item_str` could be empty when resolving in the root namespace (e.g. `::std`).
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Oh wait, I'm confused. Note that rsplit returns a reverse iterator. In this example, I think the first element would be std, right? It would not be empty.

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Here's the debug output from the assertion failure on hyper:

TRACE rustdoc::passes::collect_intra_doc_links considering link '::client'
DEBUG rustdoc::passes::collect_intra_doc_links resolving ::client as a macro in the module DefId(0:248 ~ hyper[8787]::body)
DEBUG rustdoc::passes::collect_intra_doc_links ::client resolved to Err(()) in namespace TypeNS
DEBUG rustdoc::passes::collect_intra_doc_links  resolved to Err(()) in namespace TypeNS
DEBUG rustdoc::passes::collect_intra_doc_links ::client resolved to Err(()) in namespace ValueNS
DEBUG rustdoc::passes::collect_intra_doc_links  resolved to Err(()) in namespace TypeNS
DEBUG rustdoc::passes::collect_intra_doc_links looking for enum variant ::client
DEBUG rustdoc::passes::collect_intra_doc_links  resolved to Err(()) in namespace TypeNS
thread 'rustc' panicked at 'assertion failed: !item_str.is_empty()', src/librustdoc/passes/collect_intra_doc_links.rs:439:9

So I think what's going wrong is that resolve_variant calls resolve recursively, and on the second call the string is empty (and only has one item in the iterator). This could probably be improved but it would require a redesign of the algorithm.

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@jyn514 jyn514 Dec 12, 2020 •
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Yup, this is the backtrace:

   0: std::panicking::begin_panic
             at /home/joshua/rustc/library/std/src/panicking.rs:519:12
   1: rustdoc::passes::collect_intra_doc_links::LinkCollector::resolve
             at /home/joshua/rustc/src/librustdoc/passes/collect_intra_doc_links.rs:439:9
   2: rustdoc::passes::collect_intra_doc_links::LinkCollector::check_full_res
             at /home/joshua/rustc/src/librustdoc/passes/collect_intra_doc_links.rs:637:17
   3: rustdoc::passes::collect_intra_doc_links::resolution_failure::{{closure}}
             at /home/joshua/rustc/src/librustdoc/passes/collect_intra_doc_links.rs:1680:33
   4: rustdoc::passes::collect_intra_doc_links::report_diagnostic::{{closure}}
             at /home/joshua/rustc/src/librustdoc/passes/collect_intra_doc_links.rs:1597:9
   5: core::ops::function::FnOnce::call_once{{vtable.shim}}
             at /home/joshua/rustc/library/core/src/ops/function.rs:227:5
   6: <alloc::boxed::Box<F,A> as core::ops::function::FnOnce<Args>>::call_once
             at /home/joshua/rustc/library/alloc/src/boxed.rs:1328:9
   7: rustc_middle::lint::struct_lint_level::struct_lint_level_impl
             at /home/joshua/rustc/compiler/rustc_middle/src/lint.rs:362:9
   8: rustc_middle::lint::struct_lint_level
             at /home/joshua/rustc/compiler/rustc_middle/src/lint.rs:364:5
   9: rustc_middle::ty::context::TyCtxt::struct_span_lint_hir
             at /home/joshua/rustc/compiler/rustc_middle/src/ty/context.rs:2562:9
  10: rustdoc::passes::collect_intra_doc_links::report_diagnostic
             at /home/joshua/rustc/src/librustdoc/passes/collect_intra_doc_links.rs:1567:5
  11: rustdoc::passes::collect_intra_doc_links::resolution_failure
             at /home/joshua/rustc/src/librustdoc/passes/collect_intra_doc_links.rs:1617:5
  12: rustdoc::passes::collect_intra_doc_links::LinkCollector::resolve_with_disambiguator
             at /home/joshua/rustc/src/librustdoc/passes/collect_intra_doc_links.rs:1299:21
  13: rustdoc::passes::collect_intra_doc_links::LinkCollector::resolve_link
             at /home/joshua/rustc/src/librustdoc/passes/collect_intra_doc_links.rs:1082:39
  14: <rustdoc::passes::collect_intra_doc_links::LinkCollector as rustdoc::fold::DocFolder>::fold_item
             at /home/joshua/rustc/src/librustdoc/passes/collect_intra_doc_links.rs:909:28

Notice this is in diagnostics, not the main resole code.

let item_str = split.next().unwrap();
assert!(!item_str.is_empty());
let item_name = Symbol::intern(item_str);
let path_root = split
.next()
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