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Fix outdated doc comment #144838

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Aug 18, 2025
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Fix outdated doc comment #144838

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8 changes: 4 additions & 4 deletions src/librustdoc/clean/types.rs
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Original file line number Diff line number Diff line change
Expand Up @@ -1534,10 +1534,10 @@ impl Type {
matches!(self, Type::Path { path: Path { res: Res::Def(DefKind::TyAlias, _), .. } })
}

/// Check if two types are "the same" for documentation purposes.
/// Check if this type is a subtype of another type for documentation purposes.
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I feel like the current behavior of the function is closer to checking if another type is a subtype of this type (this was the argument flipping I mentioned in the original issue).

Maybe my intuition is backwards, so I would wait for a second opinion before renaming the function or anything, but at the very least it should at least have a not of how generics are handled.

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It seems to me that function is working exactly like self.is_doc_subtype_of(other) and example in doc comment showing it

let generic = Type::Generic(rustc_span::symbol::sym::Any);
let unit = Type::Primitive(PrimitiveType::Unit);
assert!(unit.is_doc_subtype_of(&generic, &cache));

it reads like "unit is subtype of generic" which is true, or am I missing something?

///
/// This is different from `Eq`, because it knows that things like
/// `Placeholder` are possible matches for everything.
/// `Infer` and generics have special subtyping rules.
///
/// This relation is not commutative when generics are involved:
///
Expand All @@ -1548,8 +1548,8 @@ impl Type {
/// let cache = Cache::new(false);
/// let generic = Type::Generic(rustc_span::symbol::sym::Any);
/// let unit = Type::Primitive(PrimitiveType::Unit);
/// assert!(!generic.is_same(&unit, &cache));
/// assert!(unit.is_same(&generic, &cache));
/// assert!(!generic.is_doc_subtype_of(&unit, &cache));
/// assert!(unit.is_doc_subtype_of(&generic, &cache));
/// ```
///
/// An owned type is also the same as its borrowed variants (this is commutative),
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