x.py build passing with parse error in file

[euclio]

Discovered while working on #58824.

Notice that travis passed for x86_64-gnu-llvm-6.0, but failed for mingw-check. It shouldn't pass -- there's a parse error. The build passes locally for me using ./x.py test --bless src/test/rustdoc-ui but ./build/x86_64-unknown-linux-gnu/stage2/bin/rustc -Z parse-only src/librustdoc/passes/collect_intra_doc_links.rs fails. I wonder if this is a bug in rustbuild or cargo?

No success in minimizing this, but I am able to consistently reproduce it.

[euclio]

So as to not block the linked PR, I've pushed the non-working build here:

https://github.com/euclio/rust/blob/d5c59523588121cf337f2efd70afc031634770a1/src/librustdoc/passes/collect_intra_doc_links.rs#L562

Link to failed travis here.

I also am able to reproduce this on my Mac, so it's not Linux-specific.

[euclio]

Fixed by #58903.