java.lang.IllegalAccessError: failed to access class software.amazon.smithy.model.shapes.NamedMembersShape$Builder

[daddykotex]

Reproduced in a scala REPL, but the same should happen in a regular java project with a dependency on smithy-model 1.22.0:

scala> :paste
// Entering paste mode (ctrl-D to finish)

import software.amazon.smithy.model.shapes.MemberShape
import software.amazon.smithy.model.shapes.StructureShape
import software.amazon.smithy.model.traits.ErrorTrait

val structMember = MemberShape
    .builder()
    .id("test#struct$testing")
    .target("smithy.api#Integer")
    .build()
val struct =
    StructureShape
    .builder()
    .id("test#struct")
    .addMember(structMember)
    .addTrait(new ErrorTrait("client"))
    .build()


// Exiting paste mode, now interpreting.

java.lang.IllegalAccessError: failed to access class software.amazon.smithy.model.shapes.NamedMembersShape$Builder from class $iw (software.amazon.smithy.model.shapes.NamedMembersShape$Builder is in unnamed module of loader sbt.internal.inc.classpath.ClasspathUtil$$anon$2 @2dacc87b; $iw is in unnamed module of loader scala.tools.nsc.interpreter.IMain$TranslatingClassLoader @30001570)
  ... 67 elided

But if I do:

scala> :paste
// Entering paste mode (ctrl-D to finish)

import software.amazon.smithy.model.shapes.MemberShape
import software.amazon.smithy.model.shapes.StructureShape
import software.amazon.smithy.model.traits.ErrorTrait

val structMember = MemberShape
    .builder()
    .id("test#struct$testing")
    .target("smithy.api#Integer")
    .build()
val struct =
    StructureShape
    .builder()
    .id("test#struct")
    .addTrait(new ErrorTrait("client"))
    .addMember(structMember)
    .build()


// Exiting paste mode, now interpreting.

import software.amazon.smithy.model.shapes.MemberShape
import software.amazon.smithy.model.shapes.StructureShape
import software.amazon.smithy.model.traits.ErrorTrait
val structMember: software.amazon.smithy.model.shapes.MemberShape = (member: `test#struct$testing`)
val struct: software.amazon.smithy.model.shapes.StructureShape = (structure: `test#struct`)

It works fine. The only difference is the order of the calls in the builder. If I move .addTrait(new ErrorTrait("client")) after .addMember(structMember), it fails.

[mtdowling]

I think this might be a Scala compiler issue based on scala/scala3#13841 (comment).

This test case works fine in Java (17.0.3) in the smithy-model package:

    @Test
    public void testBuilderOrder() {
        MemberShape structMember = MemberShape
                .builder()
                .id("test#struct$testing")
                .target("smithy.api#Integer")
                .build();
        StructureShape struct = StructureShape
                .builder()
                .id("test#struct")
                .addMember(structMember)
                .addTrait(new ErrorTrait("client"))
                .build();
    }

I suppose we could flatten NamedMemberShape and NamedMemberShape.Builder into StructureShape and UnionShape. I'm not sure if that would work with Scala though.

[daddykotex]

Wow, I assumed it would not be an issue on scala's side without checking. Sorry for the noise.

[kubukoz]

Also hit this, for anyone seeing this before the upstream issue in Dotty is fixed, a workaround would be to explicitly upcast the return type of id / addMember to StructureShape.Builder.

For example (with a convenience extension method to avoid extra parentheses nesting:

extension [T](it: T) def upcast[U >: T]: U = it

def mkStruct(shapeId: ShapeId, members: List[MemberShape]) = StructureShape
  .builder()
  .members(members.asJava)
  .upcast[StructureShape.Builder]
  .id(shapeId)
  .upcast[StructureShape.Builder]
  .build()