Member type of bare type variable bound to self-reference is`ResolvedRecursiveType` (unlike `T[]` or `List<T>`)
已經有一個關聯 PR 被合併了。
- #138 來自 @cowtowncoder —— 已合併
評估
研究方向
Start with TypeResolver.resolve(TypeBindings, Type) and its _completeType() helper, then compare with resolveSubtype(), which already uses _selfReferenceTarget(). Use MemberResolver and the reproduction's Sym/Base classes to see why the field value keeps a ResolvedRecursiveType while arr does not. Done when value resolves to a fully resolved type equal to the arr element type, and the existing tests still pass.
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描述
When a member's type is a bare type variable bound to a self-reference, the resolved member type is a ResolvedRecursiveType (whose getParentClass() is null and getImplementedInterfaces() empty), whereas uses of the same variable within other types (T[], List<T>) resolve to fully resolved types.
Reproduction
public static class Base<X> { public X value; public X[] arr; }
public static class Sym<T extends Sym<T>> extends Base<T> { }
TypeResolver r = new TypeResolver();
ResolvedTypeWithMembers sym = new MemberResolver(r).resolve(r.resolve(Sym.class), null, null);
// field `value`: ResolvedRecursiveType `Sym<Object>`, getParentClass() == null
// field `arr`: element type is ResolvedObjectType `Sym<Sym<Object>>`
// -> value type not equal to `arr` element type
Same happens with raw self-references, like field X value of RB for RA<T extends RB> / RB extends Base<RA>.
On 1.7 / current main both value and arr element types are ResolvedRecursiveTypes (so they are at least consistent); with 1.8 (#128) incomplete types are re-resolved when obtained via TypeResolver.resolve(TypeBindings, Type) (as done by MemberResolver), except for bare self-references, which are left as-is.
Expected
Member type for value is a stand-alone (fully resolved) type, same as arr element type, so that member types can be navigated (parent class, interfaces) and compared consistently.
Notes
Likely fix: in TypeResolver.resolve(TypeBindings, Type) (_completeType()), replace a top-level self-reference with the type it represents (_selfReferenceTarget(), as resolveSubtype() already does). This changes member types that are currently ResolvedRecursiveTypes, so it is a behavioral change (although equality with fully resolved types is retained).
- 主要語言
- Java
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- 266
- 分支
- 53
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- 8
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