[TreeUnpickler] hitting assertion failure: `-Yread-docs` enabled, but no `docCtx` is set.

[tpolecat]

Hi,

I'm running into an assertion failure here when trying to use Scala 3 with Metals (which uses InteractiveDriver, which seems to set the -Yread-docs option).

Exception in thread "pool-10-thread-9" java.lang.AssertionError: assertion failed: `-Yread-docs` enabled, but no `docCtx` is set.
        at scala.runtime.Scala3RunTime$.assertFailed(Scala3RunTime.scala:8)
        at dotty.tools.dotc.core.tasty.TreeUnpickler$TreeReader.readNewDef(TreeUnpickler.scala:901)
        at dotty.tools.dotc.core.tasty.TreeUnpickler$TreeReader.readIndexedDef(TreeUnpickler.scala:776)
        ...

This only happens for me as far as I can tell (nobody can reproduce it) but it's consistent. I was hoping someone here might be able to explain the circumstance in which this assertion would be triggered, to help us track down what's going on.

The related Metals issue is scalameta/metals#3414

Thanks!

rob

[tgodzik]

We checked and this seems to happen only on graalvm-ce-java8 and most likely MacOS

[kpodsiad]

It happens also on openjdk_1.8.0_292, so it may be related to the java version and not just the vendor.

[smarter]

This needs reproduction steps to be actionable.

[tgodzik]

It seems that it works if we generate Bloop configuration from sbt, but not scalacli, so this might actually be some misconfiguration in scalacli. I will come back with some more info.

[tgodzik]

I dug a bit deeper here and it seems this is failing due to a release flag:

8 is not a valid choice for -release
  scalac -help  gives more information
exception caught when loading module class package$: java.lang.AssertionError: assertion failed: `-Yread-docs` enabled, but no `docCtx` is set.
exception caught when loading module class language$: java.lang.AssertionError: assertion failed: `-Yread-docs` enabled, but no `docCtx` is set.
Exception in thread "pool-6-thread-5" java.lang.AssertionError: assertion failed: `-Yread-docs` enabled, but no `docCtx` is set.

If I remove -release 8 it works, but 8 should be a valid choice here. Why would it break?

[tgodzik]

Actually, this got already fixed by #13811