rustdoc: Don't inline impls from doc(hidden) modules

[mitaa]

fixes #29584

r? @alexcrichton

[mitaa]

I'm not entirely sure if this is the right fix. On the one hand this is already done when inlining specific impls, but OTOH there is the pass strip-hidden which this maybe should be somehow coupled to.

edit: Well, I'm sure that this is the right fix, just not sure whether this should also be somehow toggled by strip-hidden

[alexcrichton]

Hm, it's tough to say what the interaction should be here is. Items can be exported from a #[doc(hidden)] module but then again you may also want to hide everything in a #[doc(hidden)] module.

Right now I think it's a rare enough pattern that we should take this for now, however. Can you be sure to add a test for this though?

[mitaa]

Forgot to commit the test.. 😐

(updated)

[alexcrichton]

@bors: r+ eae9f46

[bors]

⌛ Testing commit eae9f46 with merge 64b4b6d...

[bors]

☀️ Test successful - auto-linux-32-nopt-t, auto-linux-32-opt, auto-linux-64-debug-opt, auto-linux-64-nopt-t, auto-linux-64-opt, auto-linux-64-x-android-t, auto-linux-cross-opt, auto-linux-musl-64-opt, auto-mac-32-opt, auto-mac-64-nopt-t, auto-mac-64-opt, auto-mac-ios-opt, auto-win-gnu-32-nopt-t, auto-win-gnu-32-opt, auto-win-gnu-64-nopt-t, auto-win-gnu-64-opt, auto-win-msvc-32-opt, auto-win-msvc-64-opt