Add docs to librustc/hir/check_attr.rs

[bjorn3]

Also moved check_attribute up to ease reading.

[rust-highfive]

r? @pnkfelix

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[Mark-Simulacrum]

Looks like there are some tidy errors here:

tidy check (x86_64-unknown-linux-gnu)
[00:02:31] tidy error: /checkout/src/librustc/hir/check_attr.rs:39: trailing whitespace
[00:02:31] tidy error: /checkout/src/librustc/hir/check_attr.rs:56: trailing whitespace
[00:02:31] tidy error: /checkout/src/librustc/hir/check_attr.rs:65: trailing whitespace
[00:02:32] some tidy checks failed

[bjorn3]

fixed tidy errors

[arielb1]

r? @michaelwoerister (I think)

[michaelwoerister]

Thanks for the PR, @bjorn3! I've added a comment below.

[michaelwoerister]

I'm not sure if this doc comment is useful. I would prefer a module-level comment saying something like:

//! This module implements some validity checks for attributes.
//! In particular it verifies that `#[inline]` and `#[repr]` attributes are 
//! attached to items that actually support them and if there are
//! conflicts between multiple such attributes attached to the same 
//! item.

[bjorn3]

Changed it

[michaelwoerister]

Thank you! There is some trailing whitespace on some lines that makes make tidy fail:
https://travis-ci.org/rust-lang/rust/jobs/240885005#L721

Looks good to me otherwise.

[bjorn3]

Removed trailing whitespace

[Mark-Simulacrum]

@bors r=michaelwoerister

[bors]

📌 Commit f4d89ba has been approved by michaelwoerister

[Mark-Simulacrum]

Actually, could you squash these commits down to one please? Thanks!

@bors r-

[bjorn3]

Squashed

[Mark-Simulacrum]

Thanks!

@bors r=michaelwoerister rollup

[bors]

📌 Commit e759370 has been approved by michaelwoerister