2.13.12 regression? Third-party macro gives `NoSuchMethodError` in void `Trees$TypeTreeWithDeferredRefCheck`

[bursauxa]

Reproduction steps

• Have a Play project that depends on "ai.x" %% "play-json-extensions" % "0.42.0"
• Use the dependency to serialize a case class with more than 22 parameters (its primary use), e.g.

  implicit val format: OFormat[MyBigCaseClass] = ai.x.play.json.Jsonx.formatCaseClass[MyBigCaseClass]

• Upgrade to Scala 2.13.12

Problem

The project no longer compiles. Relevant stack trace:

[error] java.lang.NoSuchMethodError: 'void scala.tools.nsc.ast.Trees$TypeTreeWithDeferredRefCheck.(scala.tools.nsc.Global, scala.Function0)'
[error] ai.x.play.json.Macros.verifyKnownDirectSubclassesPostTyper(play-json.scala:353)
[error] ai.x.play.json.Macros.formatSealedInternal(play-json.scala:444)
[error] ai.x.play.json.Macros.formatSealed(play-json.scala:396)
[error] java.base/jdk.internal.reflect.NativeMethodAccessorImpl.invoke0(Native Method)
[error] java.base/jdk.internal.reflect.NativeMethodAccessorImpl.invoke(NativeMethodAccessorImpl.java:62)
[error] java.base/jdk.internal.reflect.DelegatingMethodAccessorImpl.invoke(DelegatingMethodAccessorImpl.java:43)
[error] java.base/java.lang.reflect.Method.invoke(Method.java:566)
[error] scala.reflect.macros.runtime.JavaReflectionRuntimes$JavaReflectionResolvers.$anonfun$resolveJavaReflectionRuntime$5(JavaReflectionRuntimes.scala:45)
[error] scala.tools.nsc.typechecker.Macros.macroExpandWithRuntime(Macros.scala:796)

This looks like a breaking change with a method that was removed (or renamed, replaced...).

[SethTisue]

Thank you for the report.

Note that it's normal for internal compiler APIs such as scala.tools.nsc.ast.Trees to change in Scala 2 minor releases. (Scala 2 version numbers are epic.major.minor.)

Regardless, it's certainly possible we'll conclude we broke compatibility in a way we shouldn't have and that might be reversible. But deciding that would involve some back-and-forth about specifics with the authors of the macro in question (or with someone who understands the macro well, if the authors aren't available).

[SethTisue]

@lrytz @som-snytt does the exception spark any guesses at what the responsible Scala PR might have been? scala/scala#10494 , perhaps?

[som-snytt]

That's the one. IIRC I needed the field for development and there was a comment to add it. I don't see that it's exploited in that ticket, however.

[lrytz]

c.universe.asInstanceOf[scala.tools.nsc.Global] and the library is not fully cross-built 😕

The library doesn't seem to be active, the last commit was 3.5 years ago - @caente is that project still relevant to you?

[SethTisue]

c.universe.asInstanceOf[scala.tools.nsc.Global] and the library is not fully cross-built 😕

Ah, okay, it's an outlaw twice over, then. So I suspect we will end up simply closing this ticket.

[bursauxa]

Ah, okay, it's an outlaw twice over, then. So I suspect we will end up simply closing this ticket.

Although it is problematic for us down the line, I can understand the rationale for that. Just let us know when you have reached a decision.

[SethTisue]

Sorry! If you fork the repo and have questions about how to make it work with 2.13.12, let us know.

[bursauxa]

It is unlikely we will do that. Probably we stick with 2.13.11, and wait for Scala 3 migration to be possible for us, as the 22 field case class limit is resolved with it (and we can drop the ai.x library).

Thanks for the heads-up @SethTisue .

[rtyley]

We've also encountered this issue - we're currently trying to figure out what to do, as we're not just using the play-json-extensions library for its 22 field case class limit fix, we're also using it for other functionality like the Jsonx.formatSealed[] method - quite a big code change to get from Scala 2.13.11 to 2.13.12.