Add document-private-items flag to cargo doc

[roblabla]

Add a --document-private-items flag to cargo doc, that mimics the equivalent cargo rustdoc -- --document-private-items. This works by relaying the flag to the underlying rustdoc call.

[rust-highfive]

Thanks for the pull request, and welcome! The Rust team is excited to review your changes, and you should hear from @matklad (or someone else) soon.

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[matklad]

Could this be handled by using cargo rustdoc -- --document-private-itmes?

[roblabla]

I tried to use it, but couldn't figure out how to make it work. Reason is, I'm using xargo and my crate only compiles for a specific target (it errors out on others). So to document it, I need the ability to specify a specific target, e.g. xargo doc --target=i386-unknown-none. Doing so, I lose the ability to document private items, hence the feature request. xargo rustdoc doesn't work because I can't specify a target, and using rustdoc itself means I need to specify a sysroot manually...

I'm pretty sure I could somehow figure out the correct sequence of commands to get rustdoc to do what I want, but it seemed easier to just add the ability to document private items in cargo doc.

[matklad]

Hm, looks like this is a bug in cargo rustdoc, it should support --target. Filed #5587 for that.

[matklad]

@roblabla now cargo rustdoc supports the —target flag. Will it work for your case?

[alexcrichton]

ping @roblabla, any updates on this PR? It looks like it may be ready to go with a test?

[roblabla]

Yeah, this PR should work (I've been using it in a personal project for a while now). I'll add a test case. I suppose it would go in tests/testsuite/doc.rs ?

[alexcrichton]

Indeed!

[alexcrichton]

@roblabla any luck adding the test case?

[roblabla]

Alright, sorry for the long wait, I finally got around to adding a proper test case for this.

[alexcrichton]

@bors: r+

Thanks!

[bors]

📌 Commit 7757753 has been approved by alexcrichton

[bors]

⌛ Testing commit 7757753 with merge 06721dd...

[bors]

☀️ Test successful - status-appveyor, status-travis
Approved by: alexcrichton
Pushing 06721dd to master...