use smallvec::{smallvec, SmallVec};
use stdx::never;
-use crate::{infer::normalize, AdtId, Interner, Scalar, Ty, TyExt, TyKind};
+use crate::{
+ infer::normalize, inhabitedness::is_enum_variant_uninhabited_from, AdtId, Interner, Scalar, Ty,
+ TyExt, TyKind,
+};
use super::{
is_box,
TyKind::Scalar(Scalar::Bool) => smallvec![make_range(0, 1, Scalar::Bool)],
// TyKind::Array(..) if ... => unhandled(),
TyKind::Array(..) | TyKind::Slice(..) => unhandled(),
- &TyKind::Adt(AdtId(hir_def::AdtId::EnumId(enum_id)), ..) => {
- let enum_data = cx.db.enum_data(enum_id);
+ TyKind::Adt(AdtId(hir_def::AdtId::EnumId(enum_id)), subst) => {
+ let enum_data = cx.db.enum_data(*enum_id);
// If the enum is declared as `#[non_exhaustive]`, we treat it as if it had an
// additional "unknown" constructor.
let mut ctors: SmallVec<[_; 1]> = enum_data
.variants
.iter()
- .filter(|&(_, _v)| {
+ .map(|(local_id, _)| EnumVariantId { parent: *enum_id, local_id })
+ .filter(|&variant| {
// If `exhaustive_patterns` is enabled, we exclude variants known to be
// uninhabited.
let is_uninhabited = is_exhaustive_pat_feature
- && unimplemented!("after MatchCheckCtx.feature_exhaustive_patterns()");
+ && is_enum_variant_uninhabited_from(variant, subst, cx.module, cx.db);
!is_uninhabited
})
- .map(|(local_id, _)| Variant(EnumVariantId { parent: enum_id, local_id }))
+ .map(Variant)
.collect();
if is_secretly_empty || is_declared_nonexhaustive {
use std::iter::once;
use hir_def::{AdtId, DefWithBodyId, HasModule, ModuleId};
+use once_cell::unsync::OnceCell;
use smallvec::{smallvec, SmallVec};
use typed_arena::Arena;
-use crate::{db::HirDatabase, Ty, TyExt};
+use crate::{db::HirDatabase, inhabitedness::is_ty_uninhabited_from, Ty, TyExt};
use super::deconstruct_pat::{Constructor, DeconstructedPat, Fields, SplitWildcard};
pub(crate) db: &'a dyn HirDatabase,
/// Lowered patterns from arms plus generated by the check.
pub(crate) pattern_arena: &'p Arena<DeconstructedPat<'p>>,
+ feature_exhaustive_patterns: OnceCell<bool>,
}
impl<'a, 'p> MatchCheckCtx<'a, 'p> {
- pub(super) fn is_uninhabited(&self, _ty: &Ty) -> bool {
- // FIXME(iDawer) implement exhaustive_patterns feature. More info in:
- // Tracking issue for RFC 1872: exhaustive_patterns feature https://github.com/rust-lang/rust/issues/51085
- false
+ pub(crate) fn new(
+ module: ModuleId,
+ body: DefWithBodyId,
+ db: &'a dyn HirDatabase,
+ pattern_arena: &'p Arena<DeconstructedPat<'p>>,
+ ) -> Self {
+ Self { module, body, db, pattern_arena, feature_exhaustive_patterns: Default::default() }
+ }
+
+ pub(super) fn is_uninhabited(&self, ty: &Ty) -> bool {
+ if self.feature_exhaustive_patterns() {
+ is_ty_uninhabited_from(ty, self.module, self.db)
+ } else {
+ false
+ }
}
/// Returns whether the given type is an enum from another crate declared `#[non_exhaustive]`.
}
}
- // Rust feature described as "Allows exhaustive pattern matching on types that contain uninhabited types."
+ // Rust's unstable feature described as "Allows exhaustive pattern matching on types that contain uninhabited types."
pub(super) fn feature_exhaustive_patterns(&self) -> bool {
- // FIXME see MatchCheckCtx::is_uninhabited
- false
+ *self.feature_exhaustive_patterns.get_or_init(|| {
+ let def_map = self.db.crate_def_map(self.module.krate());
+ let root_mod = def_map.module_id(def_map.root());
+ let rood_attrs = self.db.attrs(root_mod.into());
+ let mut nightly_features = rood_attrs
+ .by_key("feature")
+ .attrs()
+ .map(|attr| attr.parse_path_comma_token_tree())
+ .flatten()
+ .flatten();
+ nightly_features.any(
+ |feat| matches!(feat.segments(), [name] if name.to_smol_str() == "exhaustive_patterns"),
+ )
+ })
}
}
--- /dev/null
+use std::ops::ControlFlow::{self, Break, Continue};
+
+use chalk_ir::{
+ visit::{TypeSuperVisitable, TypeVisitable, TypeVisitor},
+ DebruijnIndex,
+};
+use hir_def::{
+ adt::VariantData, attr::Attrs, type_ref::ConstScalar, visibility::Visibility, AdtId,
+ EnumVariantId, HasModule, Lookup, ModuleId, VariantId,
+};
+
+use crate::{
+ db::HirDatabase, Binders, ConcreteConst, Const, ConstValue, Interner, Substitution, Ty, TyKind,
+};
+
+pub(crate) fn is_ty_uninhabited_from(ty: &Ty, target_mod: ModuleId, db: &dyn HirDatabase) -> bool {
+ let mut uninhabited_from = UninhabitedFrom { target_mod, db };
+ let inhabitedness = ty.visit_with(&mut uninhabited_from, DebruijnIndex::INNERMOST);
+ inhabitedness == BREAK_VISIBLY_UNINHABITED
+}
+
+pub(crate) fn is_enum_variant_uninhabited_from(
+ variant: EnumVariantId,
+ subst: &Substitution,
+ target_mod: ModuleId,
+ db: &dyn HirDatabase,
+) -> bool {
+ let enum_data = db.enum_data(variant.parent);
+ let vars_attrs = db.variants_attrs(variant.parent);
+ let is_local = variant.parent.lookup(db.upcast()).container.krate() == target_mod.krate();
+
+ let mut uninhabited_from = UninhabitedFrom { target_mod, db };
+ let inhabitedness = uninhabited_from.visit_variant(
+ variant.into(),
+ &enum_data.variants[variant.local_id].variant_data,
+ subst,
+ &vars_attrs[variant.local_id],
+ is_local,
+ );
+ inhabitedness == BREAK_VISIBLY_UNINHABITED
+}
+
+struct UninhabitedFrom<'a> {
+ target_mod: ModuleId,
+ db: &'a dyn HirDatabase,
+}
+
+const CONTINUE_OPAQUELY_INHABITED: ControlFlow<VisiblyUninhabited> = Continue(());
+const BREAK_VISIBLY_UNINHABITED: ControlFlow<VisiblyUninhabited> = Break(VisiblyUninhabited);
+#[derive(PartialEq, Eq)]
+struct VisiblyUninhabited;
+
+impl TypeVisitor<Interner> for UninhabitedFrom<'_> {
+ type BreakTy = VisiblyUninhabited;
+
+ fn as_dyn(&mut self) -> &mut dyn TypeVisitor<Interner, BreakTy = VisiblyUninhabited> {
+ self
+ }
+
+ fn visit_ty(
+ &mut self,
+ ty: &Ty,
+ outer_binder: DebruijnIndex,
+ ) -> ControlFlow<VisiblyUninhabited> {
+ match ty.kind(Interner) {
+ TyKind::Adt(adt, subst) => self.visit_adt(adt.0, subst),
+ TyKind::Never => BREAK_VISIBLY_UNINHABITED,
+ TyKind::Tuple(..) => ty.super_visit_with(self, outer_binder),
+ TyKind::Array(item_ty, len) => match try_usize_const(len) {
+ Some(0) | None => CONTINUE_OPAQUELY_INHABITED,
+ Some(1..) => item_ty.super_visit_with(self, outer_binder),
+ },
+
+ TyKind::Ref(..) | _ => CONTINUE_OPAQUELY_INHABITED,
+ }
+ }
+
+ fn interner(&self) -> Interner {
+ Interner
+ }
+}
+
+impl UninhabitedFrom<'_> {
+ fn visit_adt(&mut self, adt: AdtId, subst: &Substitution) -> ControlFlow<VisiblyUninhabited> {
+ let attrs = self.db.attrs(adt.into());
+ let adt_non_exhaustive = attrs.by_key("non_exhaustive").exists();
+ let is_local = adt.module(self.db.upcast()).krate() == self.target_mod.krate();
+ if adt_non_exhaustive && !is_local {
+ return CONTINUE_OPAQUELY_INHABITED;
+ }
+
+ // An ADT is uninhabited iff all its variants uninhabited.
+ match adt {
+ // rustc: For now, `union`s are never considered uninhabited.
+ AdtId::UnionId(_) => CONTINUE_OPAQUELY_INHABITED,
+ AdtId::StructId(s) => {
+ let struct_data = self.db.struct_data(s);
+ self.visit_variant(s.into(), &struct_data.variant_data, subst, &attrs, is_local)
+ }
+ AdtId::EnumId(e) => {
+ let vars_attrs = self.db.variants_attrs(e);
+ let enum_data = self.db.enum_data(e);
+
+ for (local_id, enum_var) in enum_data.variants.iter() {
+ let variant_inhabitedness = self.visit_variant(
+ EnumVariantId { parent: e, local_id }.into(),
+ &enum_var.variant_data,
+ subst,
+ &vars_attrs[local_id],
+ is_local,
+ );
+ match variant_inhabitedness {
+ Break(VisiblyUninhabited) => continue,
+ Continue(()) => return CONTINUE_OPAQUELY_INHABITED,
+ }
+ }
+ BREAK_VISIBLY_UNINHABITED
+ }
+ }
+ }
+
+ fn visit_variant(
+ &mut self,
+ variant: VariantId,
+ variant_data: &VariantData,
+ subst: &Substitution,
+ attrs: &Attrs,
+ is_local: bool,
+ ) -> ControlFlow<VisiblyUninhabited> {
+ let non_exhaustive_field_list = attrs.by_key("non_exhaustive").exists();
+ if non_exhaustive_field_list && !is_local {
+ return CONTINUE_OPAQUELY_INHABITED;
+ }
+
+ let is_enum = matches!(variant, VariantId::EnumVariantId(..));
+ let field_tys = self.db.field_types(variant);
+ let field_vis = self.db.field_visibilities(variant);
+
+ for (fid, _) in variant_data.fields().iter() {
+ self.visit_field(field_vis[fid], &field_tys[fid], subst, is_enum)?;
+ }
+ CONTINUE_OPAQUELY_INHABITED
+ }
+
+ fn visit_field(
+ &mut self,
+ vis: Visibility,
+ ty: &Binders<Ty>,
+ subst: &Substitution,
+ is_enum: bool,
+ ) -> ControlFlow<VisiblyUninhabited> {
+ let target_mod = self.target_mod;
+ let mut data_uninhabitedness =
+ || ty.clone().substitute(Interner, subst).visit_with(self, DebruijnIndex::INNERMOST);
+ if is_enum {
+ data_uninhabitedness()
+ } else {
+ match vis {
+ Visibility::Module(mod_id) if mod_id == target_mod => data_uninhabitedness(),
+ Visibility::Module(_) => CONTINUE_OPAQUELY_INHABITED,
+ Visibility::Public => data_uninhabitedness(),
+ }
+ }
+ }
+}
+
+fn try_usize_const(c: &Const) -> Option<u128> {
+ let data = &c.data(Interner);
+ if data.ty.kind(Interner) != &TyKind::Scalar(chalk_ir::Scalar::Uint(chalk_ir::UintTy::Usize)) {
+ return None;
+ }
+ match data.value {
+ ConstValue::Concrete(ConcreteConst { interned: ConstScalar::UInt(value) }) => Some(value),
+ _ => None,
+ }
+}
);
}
+ mod rust_unstable {
+ use super::*;
+
+ #[test]
+ fn rfc_1872_exhaustive_patterns() {
+ check_diagnostics_no_bails(
+ r"
+//- minicore: option, result
+#![feature(exhaustive_patterns)]
+enum Void {}
+fn test() {
+ match None::<!> { None => () }
+ match Result::<u8, !>::Ok(2) { Ok(_) => () }
+ match Result::<u8, Void>::Ok(2) { Ok(_) => () }
+ match (2, loop {}) {}
+ match Result::<!, !>::Ok(loop {}) {}
+ match (&loop {}) {} // https://github.com/rust-lang/rust/issues/50642#issuecomment-388234919
+ // ^^^^^^^^^^ error: missing match arm: type `&!` is non-empty
+}",
+ );
+ }
+
+ #[test]
+ fn rfc_1872_private_uninhabitedness() {
+ check_diagnostics_no_bails(
+ r"
+//- minicore: option
+//- /lib.rs crate:lib
+#![feature(exhaustive_patterns)]
+pub struct PrivatelyUninhabited { private_field: Void }
+enum Void {}
+fn test_local(x: Option<PrivatelyUninhabited>) {
+ match x {}
+} // ^ error: missing match arm: `None` not covered
+//- /main.rs crate:main deps:lib
+#![feature(exhaustive_patterns)]
+fn test(x: Option<lib::PrivatelyUninhabited>) {
+ match x {}
+ // ^ error: missing match arm: `None` and `Some(_)` not covered
+}",
+ );
+ }
+ }
+
mod false_negatives {
//! The implementation of match checking here is a work in progress. As we roll this out, we
//! prefer false negatives to false positives (ideally there would be no false positives). This
projects / rust.git / commitdiff