attribute-style doc comments (#[doc]) are not shown in lsp-ui-sideline

[japaric]

Steps to reproduce

Start with cargo new --bin hello then modify src/main.rs to look like this:

/// Foo!
struct Foo;

#[doc = "Bar!"]
struct Bar;

fn main() {
    let _ = Foo;
    let _ = Bar;
}

Opening the file in emacs-nox and placing the cursor on Foo (line 8) shows:

struct Foo

Foo!

on the sideline.

Placing the cursor on Bar (line 9) only shows:

struct Bar

Pictures:

Meta

$ cd rust-analyzer
$ git rev-parse HEAD
32fc890de87e25c342b7c141ef98b07cb1471128

$ rustc -V
rustc 1.43.0-nightly (433aae93e 2020-02-14)

---

I have a crate that I machine generated using quote! and all generated doc comments use #[doc] attributes. The multi-line ones look like this:

#[doc = "one line description"]
#[doc = ""]
#[doc = "more detailed description"]
pub struct Foo;

None of them show up in lsp-ui-sideline

[matklad]

Should be fixed by #3182 "refactoring", but this would constitute a good test case!