Unnamed repository; edit this file 'description' to name the repository.
Diffstat (limited to 'crates/hir-ty/src/infer/unify.rs')
| -rw-r--r-- | crates/hir-ty/src/infer/unify.rs | 36 |
1 files changed, 26 insertions, 10 deletions
diff --git a/crates/hir-ty/src/infer/unify.rs b/crates/hir-ty/src/infer/unify.rs index e4881d7520..54aa18ce20 100644 --- a/crates/hir-ty/src/infer/unify.rs +++ b/crates/hir-ty/src/infer/unify.rs @@ -916,6 +916,32 @@ impl<'a> InferenceTable<'a> { /// Check if given type is `Sized` or not pub(crate) fn is_sized(&mut self, ty: &Ty) -> bool { + let mut ty = ty.clone(); + { + let mut structs = SmallVec::<[_; 8]>::new(); + // Must use a loop here and not recursion because otherwise users will conduct completely + // artificial examples of structs that have themselves as the tail field and complain r-a crashes. + while let Some((AdtId::StructId(id), subst)) = ty.as_adt() { + let struct_data = self.db.struct_data(id); + if let Some((last_field, _)) = struct_data.variant_data.fields().iter().next_back() + { + let last_field_ty = self.db.field_types(id.into())[last_field] + .clone() + .substitute(Interner, subst); + if structs.contains(&ty) { + // A struct recursively contains itself as a tail field somewhere. + return true; // Don't overload the users with too many errors. + } + structs.push(ty); + // Structs can have DST as its last field and such cases are not handled + // as unsized by the chalk, so we do this manually. + ty = last_field_ty; + } else { + break; + }; + } + } + // Early return for some obvious types if matches!( ty.kind(Interner), @@ -930,16 +956,6 @@ impl<'a> InferenceTable<'a> { return true; } - if let Some((AdtId::StructId(id), subst)) = ty.as_adt() { - let struct_data = self.db.struct_data(id); - if let Some((last_field, _)) = struct_data.variant_data.fields().iter().last() { - let last_field_ty = - self.db.field_types(id.into())[last_field].clone().substitute(Interner, subst); - // Structs can have DST as its last field and such cases are not handled - // as unsized by the chalk, so we do this manually - return self.is_sized(&last_field_ty); - } - } let Some(sized) = self .db .lang_item(self.trait_env.krate, LangItem::Sized) |