Missing hover docs on primitive methods

[deltaphc]

Running the 2021.2.15 release.

It correctly provides completions for primitive types, but doesn't show their documentation. Not that big of a deal, but I figured I'd report it anyway since it doesn't appear to be an existing issue.

[Veykril]

This only happens for uint_impl! generated functions in std, expanding the macro invocation reveals that the expansion breaks docs/attributes I think? https://gist.github.com/Veykril/9f64c18c98553523fc0f9e8bb6c7721d
I think our expansion doesn't handle mixed doc-strings and doc attributes that well.

[edwin0cheng]

It seem like related to #7423.

[edwin0cheng]

TIL : the problem here is quite interesting , MWE :

macro_rules! doc_comment {
    ($x:expr, $($tt:tt)*) => {
        #[doc = $x]
        $($tt)*
    };
}

doc_comment! { 
    concat!("Hello"," world"),
    struct Bar;
}

And of course we don't handle this case, because it will be expanded to :

#[doc = concat!("Hello", " world")]
struct Bar;

And the interesting point is, the above expanded code is unstable in rustc too. But the macro one is stable.

[Edit]

Add #8092 for tracking the actual problem.

[edwin0cheng]

After #8550, a half of documentation is shown. 😆

To fix this, #8092 is still needed.