8000 Fix unused_result lint triggering when a function returns `()`, `!` or an empty enum by pengowen123 · Pull Request #43813 · rust-lang/rust · GitHub
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Fix unused_result lint triggering when a function returns (), ! or an empty enum #43813

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Merged
merged 2 commits into from
Aug 13, 2017
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Fix unused_result lint triggering when a function returns (), ! or an empty enum #43813

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0b2c9f0
Fix unused_result lint triggering when a function returns `()` or `!`
pengowen123 Aug 11, 2017
eeb748a
Don't trigger unused_result on functions returning empty enums
pengowen123 Aug 12, 2017
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Don't trigger unused_result on functions returning empty enums
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@pengowen123
pengowen123 committed Aug 12, 2017
commit eeb748aa12a3bb7f6bbd1205385fa0a0adbef90c
8 changes: 7 additions & 1 deletion src/librustc_lint/unused.rs
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Expand Up @@ -148,7 +148,13 @@ impl<'a, 'tcx> LateLintPass<'a, 'tcx> for UnusedResults {
let ty_warned = match t.sty {
ty::TyTuple(ref tys, _) if tys.is_empty() => return,
ty::TyNever => return,
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Should this also apply to enum Void {}, and other such uninhabited types? (Possibly like #38069?)

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Makes sense to me. I'll add that.

ty::TyAdt(def, _) => check_must_use(cx, def.did, s.span, ""),
ty::TyAdt(def, _) => {
if def.variants.is_empty() {
return;
} else {
check_must_use(cx, def.did, s.span, "")
}
},
_ => false,
};

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7 changes: 7 additions & 0 deletions src/test/ui/issue-43806.rs
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7547
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Expand Up @@ -12,15 +12,22 @@

#![deny(unused_results)]

enum Void {}

fn foo() {}

fn bar() -> ! {
loop {}
}

fn baz() -> Void {
loop {}
}

fn qux() {
foo();
bar();
baz();
}

fn main() {}
0