Don't apply string_lit_as_bytes if in macro expansion

[Centri3]

The following code will emit a warning on both w! and h!, despite there being nothing the user (or library author) could do about it:

#![warn(clippy::string_lit_as_bytes)]

use windows::w;
use windows::h;

fn main() {
    let _w = w!("example");
    let _h = h!("example");
}

This is because windows-rs will create a binding const INPUT: &[u8] = $s.as_bytes(), and changing this to b"$s" is, well, suboptimal. I don't know enough about Rust to know if this is something that can be detected though if it can be I'm happy with closing this in favor of implementing that.

I'm not sure whether this is how it should be done though, as this simply tells clippy to not invoke this even if it's applicable (this also affects the other string lints, but didn't cause any tests to fail).

changelog: [string_lit_as_bytes]: Don't lint if in external macro

[rustbot]

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[giraffate]

Thanks for creating the pull request! I made some comments. If you have any questions, feel free to ask us.

• It would be better to ignore it only in an external macro, so this would be helpful for it: fix almost_swapped: Ignore external macros #10502
• It looks like that this fix affects the string_from_utf8_as_bytes lint. At first, it would be better to fix only string_lit_as_bytes.

[Centri3]

Thanks for creating the pull request! I made some comments. If you have any questions, feel free to ask us.

* It would be better to ignore it only in an external macro, so this would be helpful for it: [fix `almost_swapped`: Ignore external macros #10502](https://github.com/rust-lang/rust-clippy/pull/10502)

* It looks like that this fix affects the `string_from_utf8_as_bytes` lint. At first, it would be better to fix only `string_lit_as_bytes`.

Thanks, I wasn't sure how to do that. Done

[bors]

☔ The latest upstream changes (presumably #10669) made this pull request unmergeable. Please resolve the merge conflicts.

[giraffate]

Overall looks good, thanks!

We follow the no merge-commit policy, so can you do the rebase the master branch, not merge? Once this is resolved, I'll merge this.
https://github.com/rust-lang/rust-clippy/blob/master/book/src/development/basics.md#pr

[giraffate]

@bors r+

Thanks!

[bors]

📌 Commit 14a6fa4 has been approved by giraffate

It is now in the queue for this repository.

[bors]

⌛ Testing commit 14a6fa4 with merge abd2c1e...

[bors]

☀️ Test successful - checks-action_dev_test, checks-action_remark_test, checks-action_test
Approved by: giraffate
Pushing abd2c1e to master...