Concrete type only used in `impl Trait` is unused #55124

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cramertj opened this issue Oct 16, 2018 · 6 comments · Fixed by #56456

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A-lints P-high regression-from-stable-to-stable T-compiler

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cramertj commented Oct 16, 2018

The following code gives "warning: enum is never used: Empty":

enum Empty { }
trait Bar<T> {}
impl Bar<Empty> for () {}

fn boo() -> impl Bar<Empty> {}

fn main() {
    boo();
}

This regressed pretty recently. cc @oli-obk

The text was updated successfully, but these errors were encountered:

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jonas-schievink commented Oct 16, 2018

1.27.0 does not warn, 1.28.0 does.

estebank added A-lints regression-from-stable-to-stable labels

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pnkfelix commented Nov 29, 2018

triage: P-medium; This seems like a papercut that should be easy to work-around (at least if one isn't using forbid...).

pnkfelix added P-medium P-high and removed P-medium labels

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pnkfelix commented Nov 29, 2018

switched to P-high after prompting from @nikomatsakis

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pnkfelix commented Nov 29, 2018

whoops forgot to tag with T-compiler in time for the meeting...

pnkfelix added the T-compiler label

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pnkfelix commented Nov 29, 2018

assigning to @nikomatsakis

pnkfelix assigned nikomatsakis

oli-obk assigned oli-obk and unassigned nikomatsakis

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oli-obk commented Dec 3, 2018

I'm grabbing this, I think I broke it and it should be easy to fix

oli-obk mentioned this issue

Handle existential types in dead code analysis #56456

Merged

kennytm added a commit to kennytm/rust that referenced this issue


          Rollup merge of rust-lang#56456 - oli-obk:private_impl_trait, r=cramertj

939de36

Handle existential types in dead code analysis

fixes rust-lang#55124

r? @cramertj

GuillaumeGomez added a commit to GuillaumeGomez/rust that referenced this issue


          Rollup merge of rust-lang#56456 - oli-obk:private_impl_trait, r=cramertj

dcb57d5

Handle existential types in dead code analysis

fixes rust-lang#55124

r? @cramertj

GuillaumeGomez added a commit to GuillaumeGomez/rust that referenced this issue


          Rollup merge of rust-lang#56456 - oli-obk:private_impl_trait, r=cramertj

17f60bd

Handle existential types in dead code analysis

fixes rust-lang#55124

r? @cramertj

pietroalbini added a commit to pietroalbini/rust that referenced this issue


          Rollup merge of rust-lang#56456 - oli-obk:private_impl_trait, r=cramertj

d71381a

Handle existential types in dead code analysis

fixes rust-lang#55124

r? @cramertj

pietroalbini added a commit to pietroalbini/rust that referenced this issue


          Rollup merge of rust-lang#56456 - oli-obk:private_impl_trait, r=cramertj

1276ffe

Handle existential types in dead code analysis

fixes rust-lang#55124

r? @cramertj

bors closed this as completed in #56456

spastorino mentioned this issue

Move private_unused.rs test to impl-trait #88136

Merged

GuillaumeGomez added a commit to GuillaumeGomez/rust that referenced this issue


          Rollup merge of rust-lang#88136 - spastorino:fix-test-directory, r=ol…

9bbb57c

…i-obk

Move private_unused.rs test to impl-trait

This test was added to fix this issue rust-lang#55124 which is about impl traits but not related with type alias impl traits.

r? `@oli-obk`

`@bors` rollup=always

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