bjoernager/rust
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Clarify the situation with dummy patterns and PatData

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Use an explicit `Option` instead of requiring a `Default` bound
This commit is contained in:
Nadrieril 2023-12-22 23:47:44 +01:00
parent f6af7478ba
commit 5fccaee59c
6 changed files with 22 additions and 20 deletions
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18
compiler/rustc_pattern_analysis/src/pat.rs
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@ -26,14 +26,16 @@ pub struct DeconstructedPat<'p, Cx: TypeCx> {
ctor: Constructor<Cx>,
fields: &'p [DeconstructedPat<'p, Cx>],
ty: Cx::Ty,
data: Cx::PatData,
/// Extra data to store in a pattern. `None` if the pattern is a wildcard that does not
/// correspond to a user-supplied pattern.
data: Option<Cx::PatData>,
/// Whether removing this arm would change the behavior of the match expression.
useful: Cell<bool>,
}
impl<'p, Cx: TypeCx> DeconstructedPat<'p, Cx> {
pub fn wildcard(ty: Cx::Ty, data: Cx::PatData) -> Self {
Self::new(Wildcard, &[], ty, data)
pub fn wildcard(ty: Cx::Ty) -> Self {
DeconstructedPat { ctor: Wildcard, fields: &[], ty, data: None, useful: Cell::new(false) }
}
pub fn new(
@ -42,7 +44,7 @@ impl<'p, Cx: TypeCx> DeconstructedPat<'p, Cx> {
ty: Cx::Ty,
data: Cx::PatData,
) -> Self {
DeconstructedPat { ctor, fields, ty, data, useful: Cell::new(false) }
DeconstructedPat { ctor, fields, ty, data: Some(data), useful: Cell::new(false) }
}
pub(crate) fn is_or_pat(&self) -> bool {
@ -63,8 +65,10 @@ impl<'p, Cx: TypeCx> DeconstructedPat<'p, Cx> {
pub fn ty(&self) -> Cx::Ty {
self.ty
}
pub fn data(&self) -> &Cx::PatData {
&self.data
/// Returns the extra data stored in a pattern. Returns `None` if the pattern is a wildcard that
/// does not correspond to a user-supplied pattern.
pub fn data(&self) -> Option<&Cx::PatData> {
self.data.as_ref()
}
pub fn iter_fields<'a>(
@ -83,7 +87,7 @@ impl<'p, Cx: TypeCx> DeconstructedPat<'p, Cx> {
let wildcard_sub_tys = || {
let tys = pcx.ctor_sub_tys(other_ctor);
tys.iter()
.map(|ty| DeconstructedPat::wildcard(*ty, Cx::PatData::default()))
.map(|ty| DeconstructedPat::wildcard(*ty))
.map(|pat| pcx.mcx.wildcard_arena.alloc(pat) as &_)
.collect()
};