On Wed, 8 Feb 2023 07:21:07 GMT, Adam Sotona <asot...@openjdk.org> wrote:
>>> Class `Signature` (aka `JavaTypeSignature`), all subclasses, >>> `MethodSignature` and `ClassSignature` are designed according to [JVMS >>> 4.7.9.1 >>> Signatures](https://docs.oracle.com/javase/specs/jvms/se19/html/jvms-4.html#jvms-4.7.9.1) >> >> The production is the same as the one I quoted, but thanks for pointing me >> at the correct one. So: >> >> >> JavaTypeSignature: >> ReferenceTypeSignature >> BaseType >> >> >> and >> >> >> ReferenceTypeSignature: >> ClassTypeSignature >> TypeVariableSignature >> ArrayTypeSignature >> >> >> So, while I can expect that `ArrayTypeSignature` *is a* `Signature` (or >> `JavaTypeSignature`), I cannot explain why `ThrowsSignature` extends >> `Signature`. That doesn't seem to follow from the production. That is, if a >> client obtains a `Signature` and wanted to pattern match, what are the cases >> it should worry about? I believe the cases are the ones listed above. >> >> One thing I missed is that e.g. `TypeParam` is *not* a signature (which is >> the only case among the nested classes in `Signature`). But >> `ThrowsSignature`, `TypeArg` and `TypeParam` are signatures even though that >> doesn't seem to be the case when looking at the production in the JVMS. If >> we want to keep these fine, but I don't think they should extend >> `Signature`, either directly or indirectly. That is, `Signature` should be a >> sealed type with 4 leaves (base-type/array/type var/class-type). > > **Specification:** > > MethodSignature: > [TypeParameters] ( {JavaTypeSignature} ) Result {ThrowsSignature} > > Result: > JavaTypeSignature > VoidDescriptor > > ThrowsSignature: > ^ ClassTypeSignature > ^ TypeVariableSignature > > > > **Reflect in API mapping:** > > public sealed interface ClassTypeSig > extends RefTypeSig, ThrowableSig > > and > > public sealed interface TypeVarSig > extends RefTypeSig, ThrowableSig > > and > > /** > * @return method signature > * @param typeParameters signatures for the type parameters > * @param exceptions sigantures for the exceptions > * @param result signature for the return type > * @param arguments signatures for the method arguments > */ > public static MethodSignature of(List<Signature.TypeParam> typeParameters, > List<Signature.ThrowableSig> exceptions, > Signature result, > Signature... arguments) { > > > `Signature.ThrowableSig` is a `Signature` and it is a common super of > `ClassTypeSig` and `TypeVarSig`. `TypeParam` is not a signature, because it simply is not a signature. Per spec: TypeParameter: Identifier ClassBound {InterfaceBound} ------------- PR: https://git.openjdk.org/jdk/pull/10982
