Add Constructor::Never
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@ -681,15 +681,19 @@ pub enum Constructor<Cx: TypeCx> {
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Or,
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/// Wildcard pattern.
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Wildcard,
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/// Never pattern. Only used in `WitnessPat`. An actual never pattern should be lowered as
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/// `Wildcard`.
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Never,
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/// Fake extra constructor for enums that aren't allowed to be matched exhaustively. Also used
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/// for those types for which we cannot list constructors explicitly, like `f64` and `str`.
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/// for those types for which we cannot list constructors explicitly, like `f64` and `str`. Only
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/// used in `WitnessPat`.
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NonExhaustive,
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/// Fake extra constructor for variants that should not be mentioned in diagnostics.
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/// We use this for variants behind an unstable gate as well as
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/// `#[doc(hidden)]` ones.
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/// Fake extra constructor for variants that should not be mentioned in diagnostics. We use this
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/// for variants behind an unstable gate as well as `#[doc(hidden)]` ones. Only used in
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/// `WitnessPat`.
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Hidden,
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/// Fake extra constructor for constructors that are not seen in the matrix, as explained at the
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/// top of the file.
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/// top of the file. Only used for specialization.
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Missing,
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/// Fake extra constructor that indicates and empty field that is private. When we encounter one
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/// we skip the column entirely so we don't observe its emptiness. Only used for specialization.
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@ -711,6 +715,7 @@ fn clone(&self) -> Self {
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Constructor::Str(value) => Constructor::Str(value.clone()),
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Constructor::Opaque(inner) => Constructor::Opaque(inner.clone()),
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Constructor::Or => Constructor::Or,
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Constructor::Never => Constructor::Never,
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Constructor::Wildcard => Constructor::Wildcard,
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Constructor::NonExhaustive => Constructor::NonExhaustive,
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Constructor::Hidden => Constructor::Hidden,
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@ -189,6 +189,7 @@ fn fmt(&self, f: &mut fmt::Formatter<'_>) -> fmt::Result {
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}
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Ok(())
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}
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Never => write!(f, "!"),
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Wildcard | Missing | NonExhaustive | Hidden | PrivateUninhabited => {
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write!(f, "_ : {:?}", pat.ty())
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}
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@ -251,7 +251,7 @@ fn reveal_and_alloc<'a, 'tcx>(
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_ => bug!("bad slice pattern {:?} {:?}", ctor, ty),
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},
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Bool(..) | IntRange(..) | F32Range(..) | F64Range(..) | Str(..) | Opaque(..)
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| NonExhaustive | Hidden | Missing | PrivateUninhabited | Wildcard => &[],
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| Never | NonExhaustive | Hidden | Missing | PrivateUninhabited | Wildcard => &[],
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Or => {
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bug!("called `Fields::wildcards` on an `Or` ctor")
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}
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@ -279,7 +279,7 @@ pub(crate) fn ctor_arity(&self, ctor: &Constructor<'p, 'tcx>, ty: RevealedTy<'tc
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Ref => 1,
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Slice(slice) => slice.arity(),
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Bool(..) | IntRange(..) | F32Range(..) | F64Range(..) | Str(..) | Opaque(..)
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| NonExhaustive | Hidden | Missing | PrivateUninhabited | Wildcard => 0,
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| Never | NonExhaustive | Hidden | Missing | PrivateUninhabited | Wildcard => 0,
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Or => bug!("The `Or` constructor doesn't have a fixed arity"),
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}
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}
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@ -809,7 +809,8 @@ pub fn hoist_witness_pat(&self, pat: &WitnessPat<'p, 'tcx>) -> Pat<'tcx> {
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}
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}
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&Str(value) => PatKind::Constant { value },
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Wildcard | NonExhaustive | Hidden | PrivateUninhabited => PatKind::Wild,
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Never if self.tcx.features().never_patterns => PatKind::Never,
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Never | Wildcard | NonExhaustive | Hidden | PrivateUninhabited => PatKind::Wild,
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Missing { .. } => bug!(
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"trying to convert a `Missing` constructor into a `Pat`; this is probably a bug,
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`Missing` should have been processed in `apply_constructors`"
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