diff --git a/compiler/rustc_mir_build/src/thir/pattern/_match.rs b/compiler/rustc_mir_build/src/thir/pattern/_match.rs index 868923be757..4bbbf416bec 100644 --- a/compiler/rustc_mir_build/src/thir/pattern/_match.rs +++ b/compiler/rustc_mir_build/src/thir/pattern/_match.rs @@ -799,11 +799,9 @@ enum Constructor<'tcx> { /// boxes for the purposes of exhaustiveness: we must not inspect them, and they /// don't count towards making a match exhaustive. Opaque, - /// Fake extra constructor for enums that aren't allowed to be matched exhaustively. + /// Fake extra constructor for enums that aren't allowed to be matched exhaustively. Also used + /// for those types for which we cannot list constructors explicitly, like `f64` and `str`. NonExhaustive, - /// Fake constructor for those types for which we can't list constructors explicitly, like - /// `f64` and `str`. - Unlistable, /// Wildcard pattern. Wildcard, } @@ -897,6 +895,7 @@ impl<'tcx> Constructor<'tcx> { /// For the simple cases, this is simply checking for equality. For the "grouped" constructors, /// this checks for inclusion. fn is_covered_by<'p>(&self, pcx: PatCtxt<'_, 'p, 'tcx>, other: &Self) -> bool { + // This must be kept in sync with `is_covered_by_any`. match (self, other) { // Wildcards cover anything (_, Wildcard) => true, @@ -939,11 +938,6 @@ impl<'tcx> Constructor<'tcx> { (Opaque, _) | (_, Opaque) => false, // Only a wildcard pattern can match the special extra constructor. (NonExhaustive, _) => false, - // If we encounter a `Single` here, this means there was only one constructor for this - // type after all. - (Unlistable, Single) => true, - // Otherwise, only a wildcard pattern can match the special extra constructor. - (Unlistable, _) => false, _ => span_bug!( pcx.span, @@ -955,7 +949,8 @@ impl<'tcx> Constructor<'tcx> { } /// Faster version of `is_covered_by` when applied to many constructors. `used_ctors` is - /// assumed to be built from `matrix.head_ctors()`, and `self` is assumed to have been split. + /// assumed to be built from `matrix.head_ctors()` with wildcards filtered out, and `self` is + /// assumed to have been split from a wildcard. fn is_covered_by_any<'p>( &self, pcx: PatCtxt<'_, 'p, 'tcx>, @@ -965,8 +960,9 @@ impl<'tcx> Constructor<'tcx> { return false; } + // This must be kept in sync with `is_covered_by`. match self { - // `used_ctors` cannot contain anything else than `Single`s. + // If `self` is `Single`, `used_ctors` cannot contain anything else than `Single`s. Single => !used_ctors.is_empty(), Variant(_) => used_ctors.iter().any(|c| c == self), IntRange(range) => used_ctors @@ -979,8 +975,6 @@ impl<'tcx> Constructor<'tcx> { .any(|other| slice.is_covered_by(other)), // This constructor is never covered by anything else NonExhaustive => false, - // This constructor is only covered by `Single`s - Unlistable => used_ctors.iter().any(|c| *c == Single), Str(..) | FloatRange(..) | Opaque | Wildcard => { bug!("found unexpected ctor in all_ctors: {:?}", self) } @@ -1064,7 +1058,7 @@ impl<'tcx> Constructor<'tcx> { &Str(value) => PatKind::Constant { value }, &FloatRange(lo, hi, end) => PatKind::Range(PatRange { lo, hi, end }), IntRange(range) => return range.to_pat(pcx.cx.tcx), - NonExhaustive | Unlistable => PatKind::Wild, + NonExhaustive => PatKind::Wild, Opaque => bug!("we should not try to apply an opaque constructor"), Wildcard => bug!( "trying to apply a wildcard constructor; this should have been done in `apply_constructors`" @@ -1213,8 +1207,9 @@ impl<'p, 'tcx> Fields<'p, 'tcx> { } _ => bug!("bad slice pattern {:?} {:?}", constructor, ty), }, - Str(..) | FloatRange(..) | IntRange(..) | NonExhaustive | Opaque | Unlistable - | Wildcard => Fields::empty(), + Str(..) | FloatRange(..) | IntRange(..) | NonExhaustive | Opaque | Wildcard => { + Fields::empty() + } }; debug!("Fields::wildcards({:?}, {:?}) = {:#?}", constructor, ty, ret); ret @@ -1624,8 +1619,8 @@ fn all_constructors<'p, 'tcx>(pcx: PatCtxt<'_, 'p, 'tcx>) -> Vec vec![], ty::Adt(..) | ty::Tuple(..) | ty::Ref(..) => vec![Single], - // This type is one for which we don't know how to list constructors, like `str` or `f64`. - _ => vec![Unlistable], + // This type is one for which we cannot list constructors, like `str` or `f64`. + _ => vec![NonExhaustive], } }