Fix unused_trait_names FP when as name is from macro input
#14947
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| // Skip if the ident of `as` is from a macro's input | ||
| && (!last_segment.ident.span.from_expansion() || ident.span.from_expansion()) |
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What is the reasoning here? Why check only the last segment? For example, the following will still trigger the lint, I'm not sure it should:
macro_rules! mac {
($i:ident) => { use $i::Tr; };
}
mac!(m);error: importing trait that is only used anonymously
--> tests/ui/unused_trait_names.rs:313:33
|
LL | ($i:ident) => { use $i::Tr; };
| ^^ help: use: `Tr as _`
LL | }
LL | mac!(m);
| ------- in this macro invocation
What do we want to see linted exactly here?
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The original implementation will lint items inside macros. Note that external macros will not be linted, only those locally since users can edit them. I think it is reasonable to ask users to change it to Tr as _ if the as part is not from the macro input. However, if the as part is from user input, like as $i, then it should not.
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Maybe we should ignore macros altogether
| @@ -73,6 +73,8 @@ impl<'tcx> LateLintPass<'tcx> for UnusedTraitNames { | |||
| && let Some(snip) = snippet_opt(cx, last_segment.ident.span) | |||
| && self.msrv.meets(cx, msrvs::UNDERSCORE_IMPORTS) | |||
| && !is_from_proc_macro(cx, &last_segment.ident) | |||
| // Skip if the ident of `as` is from a macro's input | |||
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The comment does not seem to correspond to the test which also checks the last segment.
Closes #14924
changelog: [
unused_trait_names] fix FP whenasname is from macro input