Clarify use $crate restriction
#2010
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The previous wording for this restriction was pretty confusing to me. I don't remember what I was thinking when I wrote it, and I can't find any historical explanation either. `use` paths can use `$crate` as long as they have more than one segment (`use $crate::foo` is obviously OK). I have rewritten this to make it clear it is specifically about `use $crate`. One could say that restriction is already covered by the previous point that says `use crate;` requires an `as`, but for some reason `use $crate as foo` doesn't work either. So I have left this as a separate rule for now. cc rust-lang/rust#146972 (comment) for context.
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Opening as a draft because I'm wondering how intentional this is. |
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cc @yaahc |
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https://github.com/yaahc/rust/blob/adaa838976ff99a4f0661136322f64cb466b58a0/compiler/rustc_resolve/src/build_reduced_graph.rs#L630-L631 is the logic that controls this, it doesn't make a carveout for renaming imports but it doesn't mention them either so I'm not positive if that means it was intended to also disallow this case. rust-lang/rust#45846 is the PR where this logic was introduced. I did a quick search of the discussion on this PR and the associated PR, tracking issue, and RFC (discussion and content) and honestly couldn't find any mention of the $crate syntax at all outside of the PR diff itself. If I had to guess I'd assume this was probably an oversight. @petrochenkov's comment rust-lang/rust#35612 (comment) seems to support this theory. much better example: rust-lang/rust#146972 (comment) |
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The previous wording for this restriction was pretty confusing to me. I don't remember what I was thinking when I wrote it, and I can't find any historical explanation either.
usepaths can use$crateas long as they have more than one segment (use $crate::foois obviously OK).I have rewritten this to make it clear it is specifically about
use $crate. One could say that restriction is already covered by the previous point that saysuse crate;requires anas, but for some reasonuse $crate as foodoesn't work either. So I have left this as a separate rule for now.cc rust-lang/rust#146972 (comment) for context.