[unnecessary_lazy_eval] Do not lint in external macros

[kraktus]

fix #9485, fix #9439

I didn't find a way to add a test since fps occur due to an external crate.

changelog: [unnecessary_lazy_eval] Do not lint in external macros

[rust-highfive]

r? @giraffate

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[dswij]

@kraktus FYI, I've recently added a test for Derive macro FP here. Maybe we can do something similar?

[kraktus]

Thanks, I've identified the source of the false positive in rocket codebase: https://github.com/SergioBenitez/Rocket/blob/707936177a7fea6d8eca103cf0b3601ca45fe657/core/codegen/src/derive/from_form.rs#L287

Following your example I've tried to reproduce the issue with a dummy derive macro

#[proc_macro_derive(LazyEvalDerive)]
pub fn unnecessary_lazy_eval(_: TokenStream) -> TokenStream {
    quote!(
        pub fn unnecessary_then() {
            Some(1).unwrap_or_else(|| 2); // should not lint because in external macro
        }
    )
}

but it's not linting it even before my patch, so unlikely my fix is working as intended

[Jarcho]

The fix for this needs is_from_proc_macro. You can use the with_span! macro in tests using aux-build:proc_macro_with_span.rs.

[bors]

☔ The latest upstream changes (presumably #9551) made this pull request unmergeable. Please resolve the merge conflicts.

[dswij]

LGTM, Thanks for this!

@giraffate Hope you don't mind me stealing this review 😁

[dswij]

@bors r+

[bors]

📌 Commit 6ec7759 has been approved by dswij

It is now in the queue for this repository.

[bors]

⌛ Testing commit 6ec7759 with merge 68408c5...

[bors]

☀️ Test successful - checks-action_dev_test, checks-action_remark_test, checks-action_test
Approved by: dswij
Pushing 68408c5 to master...