[src] links in beta and nightly documentation are broken

[RalfJung]

At least some of the [src] links in the beta standard library documentation are currently broken. I tried https://doc.rust-lang.org/beta/std/iter/trait.Iterator.html and https://doc.rust-lang.org/beta/std/iter/trait.IntoIterator.html.

[bluss]

Seems to affect some items that libstd reexports from libcore.

[alexcrichton]

I'd also be interested in investigating why CI isn't catching this...

[GuillaumeGomez]

The [src] link should be generated based on the "original" item instead of the current one. (spitting out the obvious)

[bluss]

Ok, good news, this bug did not migrate to stable when beta did?

[alexcrichton]

Something looks off-by-one in the gotosrc links (which is why linkchecker didn't catch this). libstd thinks the iterator trait is 3636 and libcore thinks it's 3637. Sounds like the ids used by rustdoc are perhaps no longer valid?

[GuillaumeGomez]

Taking a look.

[bluss]

Thanks for fixing this! rustdoc improvements = ❤️