diff options
| -rw-r--r-- | crates/hir-ty/src/inhabitedness.rs | 24 | ||||
| -rw-r--r-- | crates/ide-diagnostics/src/handlers/mutability_errors.rs | 35 |
2 files changed, 55 insertions, 4 deletions
diff --git a/crates/hir-ty/src/inhabitedness.rs b/crates/hir-ty/src/inhabitedness.rs index 36af78153d4..39324d27306 100644 --- a/crates/hir-ty/src/inhabitedness.rs +++ b/crates/hir-ty/src/inhabitedness.rs @@ -9,6 +9,7 @@ use hir_def::{ adt::VariantData, attr::Attrs, visibility::Visibility, AdtId, EnumVariantId, HasModule, Lookup, ModuleId, VariantId, }; +use rustc_hash::FxHashSet; use crate::{ consteval::try_const_usize, db::HirDatabase, Binders, Interner, Substitution, Ty, TyKind, @@ -16,7 +17,8 @@ use crate::{ /// Checks whether a type is visibly uninhabited from a particular module. 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 mut uninhabited_from = + UninhabitedFrom { target_mod, db, max_depth: 500, recursive_ty: FxHashSet::default() }; let inhabitedness = ty.visit_with(&mut uninhabited_from, DebruijnIndex::INNERMOST); inhabitedness == BREAK_VISIBLY_UNINHABITED } @@ -32,7 +34,8 @@ pub(crate) fn is_enum_variant_uninhabited_from( 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 mut uninhabited_from = + UninhabitedFrom { target_mod, db, max_depth: 500, recursive_ty: FxHashSet::default() }; let inhabitedness = uninhabited_from.visit_variant( variant.into(), &enum_data.variants[variant.local_id].variant_data, @@ -45,6 +48,9 @@ pub(crate) fn is_enum_variant_uninhabited_from( struct UninhabitedFrom<'a> { target_mod: ModuleId, + recursive_ty: FxHashSet<Ty>, + // guard for preventing stack overflow in non trivial non terminating types + max_depth: usize, db: &'a dyn HirDatabase, } @@ -65,7 +71,14 @@ impl TypeVisitor<Interner> for UninhabitedFrom<'_> { ty: &Ty, outer_binder: DebruijnIndex, ) -> ControlFlow<VisiblyUninhabited> { - match ty.kind(Interner) { + if self.recursive_ty.contains(ty) || self.max_depth == 0 { + // rustc considers recursive types always inhabited. I think it is valid to consider + // recursive types as always uninhabited, but we should do what rustc is doing. + return CONTINUE_OPAQUELY_INHABITED; + } + self.recursive_ty.insert(ty.clone()); + self.max_depth -= 1; + let r = 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), @@ -75,7 +88,10 @@ impl TypeVisitor<Interner> for UninhabitedFrom<'_> { }, TyKind::Ref(..) | _ => CONTINUE_OPAQUELY_INHABITED, - } + }; + self.recursive_ty.remove(ty); + self.max_depth += 1; + r } fn interner(&self) -> Interner { diff --git a/crates/ide-diagnostics/src/handlers/mutability_errors.rs b/crates/ide-diagnostics/src/handlers/mutability_errors.rs index 17a70f5701b..0b66350894a 100644 --- a/crates/ide-diagnostics/src/handlers/mutability_errors.rs +++ b/crates/ide-diagnostics/src/handlers/mutability_errors.rs @@ -693,6 +693,41 @@ fn f(inp: (Foo, Foo, Foo, Foo)) { } #[test] + // FIXME: We should have tests for `is_ty_uninhabited_from` + fn regression_14421() { + check_diagnostics( + r#" +pub enum Tree { + Node(TreeNode), + Leaf(TreeLeaf), +} + +struct Box<T>(&T); + +pub struct TreeNode { + pub depth: usize, + pub children: [Box<Tree>; 8] +} + +pub struct TreeLeaf { + pub depth: usize, + pub data: u8 +} + +pub fn test() { + let mut tree = Tree::Leaf( + //^^^^^^^^ 💡 weak: variable does not need to be mutable + TreeLeaf { + depth: 0, + data: 0 + } + ); +} +"#, + ); + } + + #[test] fn fn_traits() { check_diagnostics( r#" |