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impl Trait fails to resolve when returning ! #36375

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impl Trait fails to resolve when returning !#36375
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A-impl-traitArea: `impl Trait`. Universally / existentially quantified anonymous types with static dispatch.A-trait-systemArea: Trait systemA-type-systemArea: Type systemC-bugCategory: This is a bug.F-never_type`#![feature(never_type)]`T-compilerRelevant to the compiler team, which will review and decide on the PR/issue.T-typesRelevant to the types team, which will review and decide on the PR/issue.
@Cobrand

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@Cobrand
Cobrand
opened on Sep 10, 2016

I couldn't think of a better title.

This code doesn't compile on nightly :

#![feature(conservative_impl_trait)]
use std::ops::Add ;

fn test() -> impl Add<u32> {
    unimplemented!()
}

fn main() {}
rustc 1.13.0-nightly (378195665 2016-09-08)
error[E0277]: the trait bound `(): std::ops::Add<u32>` is not satisfied

while this does :

#![feature(conservative_impl_trait)]
use std::ops::Add ;

fn test() -> impl Add<u32> {
    if true {
        unimplemented!()
    } else {
        0
    }
}

fn main() {}

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    A-impl-traitArea: `impl Trait`. Universally / existentially quantified anonymous types with static dispatch.A-trait-systemArea: Trait systemA-type-systemArea: Type systemC-bugCategory: This is a bug.F-never_type`#![feature(never_type)]`T-compilerRelevant to the compiler team, which will review and decide on the PR/issue.T-typesRelevant to the types team, which will review and decide on the PR/issue.

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