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Improve conservative_is_uninhabited comment

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varkor 2018-10-19 15:09:07 +01:00
parent 6e5e54f735
commit a38ff377e7
1 changed files with 7 additions and 3 deletions
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10
src/librustc/ty/sty.rs
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@ -1543,10 +1543,14 @@ impl<'a, 'gcx, 'tcx> TyS<'tcx> {
}
}
/// Checks whether a type is definitely uninhabited. This is
/// conservative: for some types that are uninhabited we return `false`,
/// but we only return `true` for types that are definitely uninhabited.
/// `ty.conservative_is_uninhabited` implies that any value of type `ty`
/// will be `Abi::Uninhabited`.
pub fn conservative_is_uninhabited(&self, tcx: TyCtxt<'a, 'gcx, 'tcx>) -> bool {
// Checks whether a type is definitely uninhabited. This is
// conservative: for some types that are uninhabited we return `false`,
// but we only return `true` for types that are definitely uninhabited.
// FIXME(varkor): we can make this less conversative by substituting concrete
// type arguments.
match self.sty {
ty::Never => true,
ty::Adt(def, _) if def.is_union() => {