Compiler bugs: known, relevant and unresolved/undocumented

[MateuszKubuszok]

This ticket is intended to be a pinned list of compiler bugs that:

• have been reported
• might be mistaken for a bug in Chimney
• are still not resolved, or were resolved but were not yet described in the documentation

Documented fixes can be found in the latest version of troubleshooting section.

Compiler bugs

• Position.point on NoPosition when using: macro implicit, Wmacros:both and Xlint:unused scala/bug#12895 - reported as a bug in Chimney in java.lang.UnsupportedOperationException: Position.point on NoPosition in chimney 0.8.0 #411 - documented
• Incorrect children queried before class was discovered error when typeCheckErrors is used scala/scala3#18484 - found during 0.8.x development, makes it hard to test whether Scala 3 matches Scala 2 behavior when it comes to detecting subtype names ambiguities (tests are ignored on Scala 3 for now)
  • bug got recognized and marked as wontfix - it's not a big issue as it only affects testing with compileErrors, but we'll leave the note here to explain why we'll have to keep supporting a few tests disabled for Scala 3 only
• Consistent compiler crash, assertion failed while typechecking scala/scala3#19317 - reported as a bug in Chimney in Scary compiler error when providing Int const instead of Long #445
• Incorrect quotes reflection api flags set on Java symbols scala/scala3#20052 - reported as a bug in Chimney Cannot transform Scala class to Java class #484
• Assertion error during macro generation for an enum scala/scala3#20349 - discovered during automatisation of Scala CLI snippet testing Run examples with Scala CLI #523
• Misbehavior of macro-generated match when matching case object with lowercase name scala/scala3#20350 - reported as a bug in Chimney in ClassCastException thrown on Scala 3 when transforming sealed traits to Protobuf GeneratedEnum #479 - after all it was a bug in Chimney although it was hard to diagnose, fixed in Fix ClassCastException for lowercase objects in Scala 3 #603
• Issues with implicit lookup within macros, when object type is resolved from typeRepr.typeSymbol.children scala/scala3#21122 - discovered during the work on Improve protobuf support for sealed #568, makes one of Protobuf implicits (A <: GeneratedSealedOneOf with Singleton) not picked up by a macro on Scala 3, it might be a bug in Chimney, but for now we have to consult the compiler team
• Position of Some type generates warning scala/scala3#21672 - discovered after updating to 3.3.4 - it seems that Scala 3 is not storing the Symbol's Position for some build-in types, which triggers warning with -Xcheck-macros, it also the reason why Make sealed trait/enum matching order deterministic #543 hasn't fixed all issues with incremental compilation, so Stable order of sealed hierarchy's children when Position is resolved to 0 #623 was needed