Resolve duplicate diag message for: tests/ui/renamed_builtin_attr.rs

[grtn316]

This PR is to resolve duplicate diag messages for the renamed_builtin_attr UI test which is related to: #12379

This was caused by multiple functions calling the get_attr function resulting in the deprecated attribute to be reevaluated.

I added a state to the attr.rs file to track if the warning has already been emitted and skip the evaluation if the attribute warning has already been emitted.

changelog: [renamed_builtin_attr]: Fix duplicate diagnostics

[rustbot]

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[Alexendoo]

This one is a bit of an edge case compared to the others since it's not being caused by a single lint. Since the deduplication here is similar to what the diagnostic infrastructure is doing internally it might be worth keeping this one as a duplicate emitter

[Manishearth]

r? @Alexendoo

[grtn316]

This one is a bit of an edge case compared to the others since it's not being caused by a single lint. Since the deduplication here is similar to what the diagnostic infrastructure is doing internally it might be worth keeping this one as a duplicate emitter

Hi @Alexendoo. The only thing worth mentioning is that currently, without this fix, each deprecated attribute will be evaluated 4x which means 4 messages per attribute will be emitted. With this fix it will only be emitted once. More of a cosmetic thing but wanted to mention just in case.

[bors]

☔ The latest upstream changes (presumably #12999) made this pull request unmergeable. Please resolve the merge conflicts.

[Alexendoo]

UI wise duplicates are hidden by default, we set -Zdeduplicate-diagnostics=no to show duplicates as it may indicate an issue. You're right though that it's still being evaluated repeatedly which is wasteful, we could move the check into e.g.

rust-clippy/clippy_lints/src/attrs/mod.rs

Line 532 in 68a799a

fn check_attribute(&mut self, cx: &LateContext<'tcx>, attr: &'tcx Attribute) {

so it's only happening once per attribute

[Alexendoo]

@rustbot author